WO2019083187A1

WO2019083187A1 - Image forming apparatus and method to determine a decrease in discharging ability of a discharging member

Info

Publication number: WO2019083187A1
Application number: PCT/KR2018/011721
Authority: WO
Inventors: Katsuya Takano
Original assignee: Hp Printing Korea Co., Ltd.
Priority date: 2017-10-26
Filing date: 2018-10-04
Publication date: 2019-05-02
Also published as: JP2019078944A

Abstract

An image forming apparatus includes a photoreceptor to form an electrostatic latent image, a charging member to charge the photoreceptor, a transfer member to transfer an image of the electrostatic latent image to a transfer body, a discharging member to remove the electrostatic latent image from the photoreceptor by irradiating the photoreceptor with discharging light, a current detector to detect a charging current which flows through the charging member, and a controller to determine a decrease in discharging ability of the discharging member based on the charging current detected.

Description

IMAGE FORMING APPARATUS AND METHOD TO DETERMINE A DECREASE IN DISCHARGING ABILITY OF A DISCHARGING MEMBER

In an image forming apparatus, a toner image formed on the photoreceptor is transferred to a transfer belt or a recording medium by a transfer bias. The photoreceptor is irradiated with discharging light from a discharging member, and thus, a residual potential remaining on the photoreceptor is eliminated.

A decrease in the discharging ability of the discharging member by the contamination of the discharging member due to scattered toner or the like, a decrease in a light amount of the discharging member due to aging degradation, or the like, may lead to unevenness on the photoreceptor, thus affecting the printing quality. In some image forming apparatus, a transparent conductive electrode is provided between the photoreceptor and the discharging member, and the contamination of the discharging member is detected from a change in a detection value of the transparent conductive electrode.

FIG. 1 is a diagram schematically illustrating components of an example image forming apparatus.

FIG. 2 is a graph showing a relationship between output of a discharging member and a charging current flowing through a charging member.

FIG. 3 is a flowchart illustrating a processing operation of the example image forming apparatus shown in FIG.　1.

FIG. 4 is a diagram schematically illustrating components of an example image forming apparatus.

FIG. 5 is a flowchart illustrating a processing operation of the example image forming apparatus shown in FIG. 4.

FIG. 6 is a diagram schematically illustrating components of an example image forming apparatus .

FIG. 7 is a flowchart illustrating a processing operation of the example image forming apparatus shown in FIG.　6.

FIG. 8 is a diagram schematically illustrating components of a photoreceptor of an example image forming apparatus.

FIG. 9 is a flowchart illustrating a processing operation of the example image forming apparatus shown in FIG.　8.

In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted.

When the output of a discharging member increases, a charging current flowing through a charging member increases, and when the output of the discharging member is greater than a predetermined value, the charging current flowing through the charging member becomes approximately constant in a saturated state. When the discharging member is normal, an increase rate of the charging current flowing through the charging member with respect to a rising rate of the output of the discharging member is approximately constant. However, when discharging ability of the discharging member decreases, the increase rate of the charging current flowing through the charging member with respect to the rising rate of the output of the discharging member decreases.

As illustrated in FIG. 1, an example image forming apparatus 1 includes a photoreceptor 2, a charging member (or charger) 3, a charging power source 4, an exposure member 5, a development member 6, a transfer member 7, a transfer body 8, a discharging member (or discharger) 9, a cleaning member 10, a charging current detection unit (or current detector) 11, a display device 13, and a performance determination unit. The performance determination unit may be provided within a control device (or controller) 20, for example. The performance determination unit of this example configuration will be designated hereinafter by the reference number 20. The image forming apparatus 1 includes various additional configurations, components and/or features, further to the above-mentioned elements.

The photoreceptor 2 is a drum-like electrostatic latent image carrier (a photoreceptor drum) in which an image (a toner) is formed on a circumference surface. The photoreceptor 2, for example, is formed of an organic photoconductor (OPC). The photoreceptor 2 is rotatively driven by a driving motor (not illustrated) at a constant speed.

The charging member 3, for example a charging roller, receives power supply from the charging power source 4, and evenly charges a surface of the photoreceptor 2 at a predetermined potential. The potential charging the surface of the photoreceptor 2 may be 600 V, for example.

The charging power source 4 supplies power to the charging member 3 by applying a voltage to the charging member 3.

The exposure member 5 exposes the surface of the photoreceptor 2 which is charged by the charging member 3, according to an image formed on a recording medium. Accordingly, on the surface of the photoreceptor 2, the potential of a portion which is exposed by the exposure member 5, is changed, and thus, an electrostatic latent image is formed.

The development member 6 develops the electrostatic latent image which is formed on the surface of the photoreceptor 2 by the toner supplied from a toner tank (not illustrated). Accordingly, a toner image is formed on the surface of the photoreceptor 2.

The transfer member 7 applies a transfer bias which is a charge opposite from the toner, from the back side of the transfer body 8 (a side opposite to the photoreceptor 2). Accordingly, the toner image developed on the photoreceptor 2, is transferred to the transfer body 8.

The transfer body 8 may be a medium to which the toner image is transferred from the photoreceptor 2, or a transfer belt or a transfer roller to which the toner image is primarily transferred from the photoreceptor 2. When the transfer body 8 is the transfer belt or the transfer roller to which the toner image is primarily transferred from the photoreceptor 2, the transfer body 8 secondarily transfers the toner image which is primarily transferred from the photoreceptor 2, to the medium by a secondary transfer member (not illustrated).

The discharging member 9 irradiates the photoreceptor 2 in which the toner image is transferred to the transfer body 8 by the transfer member 7, with discharging light at setting output which is set output (an output value). The discharging light removes the residual potential remaining on the surface of the photoreceptor 2. Accordingly, the residual potential on the surface of the photoreceptor 2 is removed, and thus, the photoreceptor 2 is prepared for the next image formation. Furthermore, when the output (the power) of the discharging member 9 increases, irradiation intensity of the discharging light emitted from the discharging member 9 increases, and thus, a discharging effect increases. When the output (the power) of the discharging member 9 decreases, the irradiation intensity of the discharging light emitted from the discharging member 9 decreases, and thus, the discharging effect decreases. The discharging member 9 may comprise an erasing lamp (a light emitting device), for example, such as an LED and an EL element.

The cleaning member 10 collects the toner (the remaining toner) remaining on the photoreceptor 2 even after the toner image is primarily transferred to the transfer body 8. The cleaning member 10may comprise a cleaning blade, for example, which is in contact with the circumference surface of the photoreceptor 2.

The charging current detection unit 11 detects a charging current flowing through the charging member 3. The charging current detection unit 11 may comprise a current detector, for example, which is disposed on electrical wiring between the charging member 3 and the charging power source 4.

The display device 13 is disposed on a case of the image forming apparatus 1, and displays information instructed from the performance determination unit 20. The display device 13 may display various information items of the image forming apparatus 1, in addition to the information instructed from the performance determination unit 20.

The performance determination unit 20 determines a decrease in the discharging ability (or discharging performance) of the discharging member 9, based on the charging current which is detected by the charging current detection unit 11. The performance determination unit may be provided by data and instructions stored on the control device (or controller) 20 which may comprise for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like.

The relationship between the output of the discharging member 9 and the charging current flowing through the charging member 3 will be described with reference to FIG. 2. In FIG. 2, the output of the discharging member 9 is represented on a horizontal axis, and the charging current flowing through the charging member 3 is represented on a vertical axis. As shown in FIG. 2, when the output of the discharging member 9 increases, the charging current flowing through the charging member 3 increases, and when the output of the discharging member 9 is greater than a predetermined value, the charging current flowing through the charging member 3 becomes approximately constant in a saturated state. When the discharging member 9 is normal, as illustrated by a solid line A of FIG. 2, an increase rate of the charging current flowing through the charging member 3 with respect to a rising rate of the output of the discharging member 9 is approximately constant. For this reason, the output of the discharging member 9 at which the charging current flowing through the charging member 3 is in a saturated state, is set to output EP₀, and setting output EP₁ of the discharging member 9 is set to a value greater than the output EP₀, in consideration of the occurrence of a ghost print (or "ghost"), or the like.

However, when the discharging ability of the discharging member 9 decreases, as illustrated by broken line B in FIG. 2, the increase rate of the charging current flowing through the charging member 3 with respect to the rising rate of the output of the discharging member 9 decreases. For this reason, even when the output of the discharging member 9 is the output EP₀, the charging current flowing through the charging member 3 is not in the saturated state, and thus, even when the output of the discharging member 9 is the same, the charging current flowing through the charging member 3 decreases, compared to a case where the discharging member 9 is normal.

Therefore, the performance determination unit 20 determines the decrease in the discharging ability of the discharging member 9 by comparing a first charging current CRi₁ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9 at the setting output EP₁, with a second charging current CRi₂ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9 at comparison output EP₂ less than the setting output. The first charging current CRi₁ may also be referred to herein as a setting-output charging current CRi₁. The second charging current Cri₂ may also be referred to herein as a comparison-output charging current Cri₂. The discharging ability of the discharging member 9 may refer to ability of removing the residual potential remaining on the surface of the photoreceptor 2 by irradiation of the discharging light from the discharging member 9. The decrease in the discharging ability of the discharging member 9 indicates that the residual potential remaining on the surface of the photoreceptor 2 is not capable of being sufficiently removed. For example, the contamination of the erasing lamp configuring the discharging member 9, such as an LED and an EL element, a decrease in a light amount due to aging degradation, or the like may include example reasons for the discharging ability of the discharging member 9 to be decreased. Note that, in general, the discharging ability of the discharging member 9 gradually decreases, and thus, the degree of decrease in the discharging ability of the discharging member 9, which is determined as the decrease in the discharging ability of the discharging member 9, may be set according to the design concept or the like of the example image forming apparatus 1.

For example, when the second charging current CRi₂ is less than the first charging current CRi₁, or when the second charging current CRi₂ is less than the first charging current CRi₁ by a setting value or more, the performance determination unit 20 may determine that the discharging ability of the discharging member 9 decreases. When the discharging member 9 is normal, the comparison output EP₂ may be a value greater than the output EP₀ at which the charging current flowing through the charging member 3 is in the saturated state. The setting value used for the comparison between the second charging current CRi₂ and the first charging current CRi₁ is a value considering a variation error of the charging current, and can be an arbitrary value.

Furthermore, the performance determination unit 20 may determine the decrease in the discharging ability of the discharging member 9 by storing the charging current which is detected by the charging current detection unit 11 at the time of disposing a process cartridge (not illustrated) including the photoreceptor 2, the charging member 3, and the discharging member 9, as a standard charging current CRi₀, and then, by comparing the first charging current CRi₁ which is detected by the charging current detection unit 11, with the standard charging current CRi₀. The disposition of the process cartridge includes a case where a new process cartridge is newly disposed in the image forming apparatus 1, a case where a process cartridge which has been used in another image forming apparatus, is exchangeably disposed in the image forming apparatus 1, and the like. Accordingly, even when the comparison output EP₂ is set to a value less than or equal to the output EP₀, the first charging current CRi₁ and the second charging current CRi₂ are compared with the standard charging current CRi₀, and thus, it is possible to determine the decrease in the discharging ability of the discharging member 9. For example, when a difference between the first charging current CRi₁ and the second charging current CRi₂ is greater than a difference between the first charging current CRi₁ and the standard charging current CRi₀, or when a ratio of the second charging current CRi₂ to the first charging current CRi₁ is less than a ratio of the standard charging current CRi₀ to the first charging current CRi₁, it is possible to determine that the discharging ability of the discharging member 9 decreases.

When it is determined that the discharging ability of the discharging member 9 decreases, the performance determination unit 20 displays an alarm on the display device 13. For example, information indicating that the discharging ability of the discharging member 9 decreases, information of inquiring whether or not to continue the printing, and the like include examples of content of the alarm to be displayed on the display device 13.

An example determination method of the decrease in the discharging ability of the discharging member 9 will be described with reference to FIG. 3. The example processing illustrated in FIG. 3 is a processing operation which is performed according to the control of the performance determination unit 20.

A timing when the performance determination unit 20 determines the decrease in the discharging ability of the discharging member 9 by performing the processing operation may be set such that the processing operation is performed periodically, or such that the processing operation is performed at an arbitrary timing. For example, when printing having a printing rate of greater than or equal to a predetermined value, is performed continuously (or substantially consecutively) a predetermined number of times, the performance determination unit 20 may determine the decrease in the discharging ability of the discharging member 9 by performing the processing described above. In this case, when printing having a printing rate of greater than or equal to 20% is continuously performed 200 times (e.g. performed 200 times substantially consecutively), the performance determination unit 20 may determine the decrease in the discharging ability of the discharging member 9 by performing the processing described above. In addition, when a temperature or humidity in an environment where the image forming apparatus 1 is placed, is changed, the performance determination unit 20 may determine the decrease in the discharging ability of the discharging member 9 by performing the processing described above. In this case, when the temperature is changed by 2°C to 3°C, and the humidity is changed by 5%, the performance determination unit 20 may determine the decrease in the discharging ability of the discharging member 9 by performing the processing described above. For example, when an ambient temperature range and a humidity range are divided into a plurality of ranges, and the division corresponding to the temperature or the humidity in the environment where the image forming apparatus 1 is placed, is changed, the decrease in the discharging ability of the discharging member 9 may be determined by performing the processing described above. A temperature range of one division, for example, can be set to 2°C to 3°C, and a humidity range of one division, for example, can be set to 5%. The ambient temperature and the humidity, for example, can be acquired by an ambient temperature sensor and a humidity sensor.

As illustrated in FIG. 3, the performance determination unit 20 operates the discharging member 9 at the setting output EP₁ (S1), and at this time, acquires the first charging current CRi₁ which is detected by the charging current detection unit 11 (S2). In addition, the performance determination unit 20 operates the discharging member 9 at the comparison output EP₂ (S3), and at this time, acquires the second charging current CRi₂ which is detected by the charging current detection unit 11 (S4). Furthermore, the processing of S1 and S2 and the processing of S3 and S4 may be performed reversely or simultaneously.

The performance determination unit 20 determines whether or not the discharging ability of the discharging member 9 decreases by comparing the first charging current CRi₁ which is acquired in S2 with the second charging current CRi₂ which is acquired in S4 (S5). In S5, for example, it is determined whether or not the second charging current CRi₂ is less than the first charging current CRi₁, or whether or not the second charging current CRi₂ is less than the first charging current CRi₁ by a setting value or more. If it is determined that the second charging current CRi₂ is not less than the first charging current CRi₁, or the second charging current CRi₂ is not less than the first charging current CRi₁ by the setting value or more, it is determined that the discharging ability of the discharging member 9 does not decrease. If it is determined that the second charging current CRi₂ is less than the first charging current CRi₁, or the second charging current CRi₂ is less than the first charging current CRi₁ by the setting value or more, it is determined that the discharging ability of the discharging member 9 decreases.

If it is determined that the discharging ability of the discharging member 9 does not decrease (S5: NO), the performance determination unit 20 ends the processing. If it is determined that the discharging ability of the discharging member 9 decreases (S5: YES), the performance determination unit 20 displays the alarm on the display device 13 (S6), and then, ends the processing.

As described above, when the discharging member 9 is normal, the increase rate of the charging current flowing through the charging member 3 with respect to the rising rate of the output of the discharging member 9 is approximately constant, but when the discharging ability of the discharging member 9 decreases, the increase rate of the charging current flowing through the charging member 3 with respect to the rising rate of the output of the discharging member 9 decreases. For this reason, in the example image forming apparatus 1, the charging current flowing through the charging member 3 is detected, and thus, it is possible to determine the decrease in the discharging ability of the discharging member 9.

The setting output EP₁ of the discharging member 9, is set to a value greater than the output EP₀ at which the charging current flowing through the charging member 3 is in the saturated state, in consideration of the occurrence of a ghost print, or the like. For this reason, even when the discharging member 9 is operated at the setting output EP₁, it is difficult to determine the decrease in the discharging ability of the discharging member 9 according to the charging current flowing through the charging member 3 until the discharging ability of the discharging member 9 considerably decreases. However, in the image forming apparatus 1, the first charging current CRi₁ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9 at the setting output EP₁, is compared with the second charging current CRi₂ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9 at the comparison output EP₂ less than the setting output EP₁, and thus, it is possible to determine the decrease in the discharging ability of the discharging member 9 in an early stage.

In addition, when it is determined that the discharging ability of the discharging member 9 decreases, the alarm is displayed on the display device 13, and thus, it is possible to urge the user to wipe out the discharging member 9, stop printing, or the like.

In addition, the stored standard charging current CRi₀ is compared with the first charging current CRi₁ and the second charging current CRi₂, which are detected by the charging current detection unit 11, in order to determine the decrease in the discharging ability of the discharging member 9.

In addition, the decrease in the discharging ability of the discharging member 9 may be determined when the temperature or the humidity in the environment where the image forming apparatus 1 is placed, is changed.

In addition, the decrease in the discharging ability of the discharging member 9 may be determined when the printing having a printing rate of greater than or equal to a predetermined value is continuously performed a predetermined number of times (e.g. performed substantially consecutively a predetermined number of times).

With reference to FIG. 4 and 5, an example image forming apparatus includes a wiping member.

As illustrated in FIG. 4, the example image forming apparatus 1A includes a photoreceptor 2, a charging member 3, a charging power source 4, an exposure member 5, a development member 6, a transfer member 7, a transfer body 8, a discharging member 9, a cleaning member 10, a charging current detection unit 11, a display device 13, a wiping member 14, and a performance determination unit 20.

The wiping member 14 is a member wiping out the discharging member 9. The wiping member 14, for example, is configured of a member which mechanically wipes out a lens of the discharging member 9, emitting the discharging light, with a cloth or a belt. When it is determined that the discharging ability of the discharging member 9 decreases, the performance determination unit 20 wipes out the discharging member 9 by the wiping member 14.

An example determination method of the decrease in the discharging ability of the discharging member 9 will be described with reference to FIG. 5. The processing illustrated in FIG. 5 may be performed according to the control of the performance determination unit 20. Furthermore, a timing when the decrease in the discharging ability of the discharging member 9 is determined by performing the processing operation, may be similar to that of the example shown in FIG. 1 and　3.

As illustrated in FIG. 5, the performance determination unit 20 performs S1 to S4, similarly to FIG. 3, to determine whether or not the discharging ability of the discharging member 9 decreases by comparing the first charging current CRi₁ acquired at S2, with the second charging current CRi₂ acquired at S4 (S5).

If it is determined that the discharging ability of the discharging member 9 does not decrease (S5: NO), the performance determination unit 20 ends the processing.

If it is determined that the discharging ability of the discharging member 9 decreases (S5: YES), the performance determination unit 20 determines whether or not the number of times of wiping of the wiping member 14 with respect to the discharging member 9 is 0, that is, whether or not the wiping member 14 does not wipe out the discharging member 9 (S7). When it is determined that the number of times of wiping of the wiping member 14 with respect to the discharging member 9 is 0 (S7: YES), the performance determination unit 20 wipes the discharging member 9 by the wiping member 14 (S8), and ends the processing. At this time, the number of times of wiping of the wiping member 14 with respect to the discharging member 9, is incremented by 1. When it is determined that the number of times of wiping of the wiping member 14 with respect to the discharging member 9 is not 0 (S7: NO), the performance determination unit 20 displays the alarm on the display device 13 (S6), and ends the processing.

As described above, when it is determined that the discharging ability of the discharging member 9 decreases, the wiping member 14 wipes out the discharging member 9, and thus, it is possible to reactivate the discharging ability of the discharging member 9, before the discharging ability of the discharging member 9 decreases considerably.

An example image forming apparatus will be described with reference to FIG. 6 and 7.

As illustrated in FIG. 6, an example image forming apparatus 1B includes a photoreceptor 2, a charging member 3, a charging power source 4, a exposure member 5, a development member 6, a transfer member 7, a transfer body 8, a discharging member 9, a cleaning member 10, a charging current detection unit 11, a display device 13, and a performance determination unit. The performance determination unit may be provided within a control device (or controller) 21.

The performance determination unit may be provided within the control device (or controller) 21 which may comprise a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like. The performance determination unit of this example configuration will be designated hereinafter by the reference number 21.

As described above, when the discharging ability of the discharging member 9 decreases, the charging current at the time of operating the discharging member 9, decreases. On the other hand, even when the discharging ability of the discharging member 9 decreases, the charging current at the time of operating the exposure member 5 is rarely changed. Therefore, the performance determination unit 21 determines the decrease in the discharging ability of the discharging member 9 by comparing a third charging current CRi₃ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9, with a fourth charging current CRi₄ which is detected by the charging current detection unit 11 at the time of operating the exposure member 5. The third charging current Cri₃ may also be referred to herein as a discharger-operation charging current Cri₃. The fourth charging current Cri₄ may also be referred to herein as an exposure-operation charging current Cri₄. The third charging current CRi₃ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9, is the third charging current CRi₃ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9 without operating the exposure member 5. In addition, the fourth charging current CRi₄ which is detected by the charging current detection unit 11 at the time of operating the exposure member 5, is the fourth charging current CRi₄ which is detected by the charging current detection unit 11 at the time of operating the exposure member 5 without operating the discharging member 9.

For example, the performance determination unit 21, may first, obtains a proportion between the third charging current CRi₃ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9 and the fourth charging current CRi₄ which is detected by the charging current detection unit 11 at the time of operating the exposure member 5, as the comparison between the third charging current CRi₃ and the fourth charging current CRi₄. The output at the time of operating the discharging member 9 may be a value less than the setting output EP₁ of the discharging member 9, and when the discharging member 9 is normal, the output at the time of operating the discharging member 9 may be a value greater than the output EP₀ at which the charging current flowing through the charging member 3 is in the saturated state.

The performance determination unit 21 may compare the obtained proportion with a standard proportion. The standard proportion is a proportion between the third charging current CRi₃ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9, and the fourth charging current CRi₄ which is detected by the charging current detection unit 11 at the time of operating the exposure member 5, when the discharging member 9 is normal. The standard proportion, for example, can be a proportion between the third charging current CRi₃ which is detected by the charging current detection unit 11 at the time of disposing the process cartridge (not illustrated) including the photoreceptor 2, the charging member 3, and the discharging member 9, and the fourth charging current CRi₄ which is detected by the charging current detection unit 11 at the time of operating the exposure member 5.

If the obtained proportion varies from the standard proportion, or if the obtained proportion varies from the standard proportion by a predetermined value or more, the performance determination unit 21 determines that the discharging ability of the discharging member 9 decreases. A setting value used for the comparison with the standard proportion, is a value considering a variation error of the charging current, and can be an arbitrary value.

The determination method of the decrease in the discharging ability of the discharging member 9 will be described with reference to FIG. 7. The processing illustrated in FIG. 7, is a processing operation which is performed according to the control of the performance determination unit 21. Furthermore, a timing when the decrease in the discharging ability of the discharging member 9 is determined by performing the processing operation, may be similar to that of the example shown in FIG. 1 and 3.

As illustrated in FIG. 7, the performance determination unit 21 operates the discharging member 9 (S11), and at this time, acquires the third charging current CRi₃ which is detected by the charging current detection unit 11 (S12). In addition, the performance determination unit 21 operates the discharging member 9 (S13), and at this time, acquires the fourth charging current CRi₄ which is detected by the charging current detection unit 11 (S14). Furthermore, the processing of S11 and S12 and the processing of S13 and S14 may be performed reversely or simultaneously.

The performance determination unit 21 determines whether or not the discharging ability of the discharging member 9 decreases by comparing the third charging current CRi₃ acquired at S12, with the fourth charging current CRi₄ acquired at S14 (S15). At S5, for example, it is determined whether or not the proportion between the third charging current CRi₃ acquired at S12 and the fourth charging current CRi₄ acquired at S14, varies from the standard proportion, or varies from the standard proportion by a predetermined value or more. If it is determined that the proportion between the third charging current CRi₃ acquired at S12 and the fourth charging current CRi₄ acquired at S14, does not vary from the standard proportion, or does not vary from the standard proportion by a predetermined value or more, it is determined that the discharging ability of the discharging member 9 does not decrease. If it is determined that the proportion between the third charging current CRi₃ acquired at S12 and the fourth charging current CRi₄ acquired at S14, varies from the standard proportion, or varies from the standard proportion by a predetermined value or more, it is determined that the discharging ability of the discharging member 9 decreases.

If it is determined that the discharging ability of the discharging member 9 does not decrease (S15: NO), the performance determination unit 21 ends the processing. If it is determined that the discharging ability of the discharging member 9 decreases (S15: YES), the performance determination unit 21 displays the alarm on the display device 13 (S16), and then, ends the processing.

As described above, when the discharging ability of the discharging member 9 decreases, the charging current at the time of operating the discharging member 9 decreases, but the charging current at the time of operating the exposure member 5 is rarely changed. Therefore, it is possible to determine the decrease in the discharging ability of the discharging member 9 by comparing the third charging current CRi₃ which is detected by the charging current detection unit 11 at the time of operating the discharging member 9, with the fourth charging current CRi₄ which is detected by the charging current detection unit 11 at the time of operating the exposure member 5.

An example image forming apparatus will be described with reference to FIG. 8 and 9.

As illustrated in FIG. 8, an example image forming apparatus 1C includes a photoreceptor 2, a charging member 3, a charging power source 4, a exposure member 5, a development member 6, a transfer member 7, a transfer body 8, a discharging member 9, a cleaning member 10, a charging current detection unit 11, a display device 13, a wiping member 14, and a performance determination unit 21.

The wiping member 14 may be similar to the wiping member 14 of the example shown in FIG.4 and 5, and may include a member for wiping out the discharging member 9. If it is determined that the discharging ability of the discharging member 9 decreases, the performance determination unit 21 wipes out the discharging member 9 via the wiping member 14.

The determination method of the decrease in the discharging ability of the discharging member 9 will be described with reference to FIG. 9. The processing illustrated in FIG. 9, is a processing operation which is performed according to the control of the performance determination unit 21. Furthermore, a timing when the decrease in the discharging ability of the discharging member 9 is determined by performing the processing operation, may be similar to that of the example shown in FIG. 1 and 3.

As illustrated in FIG. 9, the performance determination unit 21 may perform S11 to S14, similarly to the example shown in FIG. 7, in order to determine whether or not the discharging ability of the discharging member 9 decreases by comparing the third charging current CRi₃ acquired at S12, with the fourth charging current CRi₄ acquired at S14 (S15).

When it is determined that the discharging ability of the discharging member 9 does not decrease (S15: NO), the performance determination unit 21 ends the processing.

If it is determined that the discharging ability of the discharging member 9 decreases (S15: YES), the performance determination unit 21 determines whether or not the number of times of wiping of the wiping member 14 with respect to the discharging member 9 is 0, that is, whether or not the wiping member 14 does not wipe out the discharging member 9 (S17). If it is determined that the number of times of wiping of the wiping member 14 with respect to the discharging member 9 is 0 (S17: YES), the performance determination unit 21 wipes out the discharging member 9 by the wiping member 14 (S18), and ends the processing. At this time, 1 is added to the number of times of wiping of the wiping member 14 with respect to the discharging member 9. If it is determined that the number of times of wiping of the wiping member 14 with respect to the discharging member 9 is not 0 (S17: NO), the performance determination unit 20 displays the alarm on the display device 13 (S16), and then, ends the processing.

As described above, , when it is determined that the discharging ability of the discharging member 9 decreases, the wiping member 14 wipes out the discharging member 9, and thus, it is possible to reactivate the discharging ability of the discharging member 9, before the discharging ability of the discharging member 9 considerably decreases.

Various example image forming apparatus and example features thereof will be described.

An example image forming apparatus includes: a photoreceptor; a charging member charging the photoreceptor; an exposure member forming an electrostatic latent image on the photoreceptor by exposing the photoreceptor which is charged by the charging member; a development member developing the electrostatic latent image which is formed on the photoreceptor by the exposure member; a transfer member transferring an image which is developed on the photoreceptor, to a transfer body; a discharging member removing the electrostatic latent image which remains on the photoreceptor, by irradiating the photoreceptor with discharging light at setting output; a charging current detection unit detecting a charging current which flows through the charging member; and a performance determination unit determining a decrease in discharging ability of the discharging member, in which the performance determination unit determines the decrease in the discharging ability of the discharging member, based on the charging current which is detected by the charging current detection unit.

When the discharging member is normal, the increase rate of the charging current flowing through the charging member with respect to the rising rate of the output of the discharging member is approximately constant, but when the discharging ability of the discharging member decreases, the increase rate of the charging current flowing through the charging member with respect to the rising rate of the output of the discharging member decreases. For this reason, the charging current flowing through the charging member is detected, in order to determine the decrease in the discharging ability of the discharging member.

The performance determination unit may determine the decrease in the discharging ability of the discharging member by comparing a first charging current which is detected by the charging current detection unit at the time of operating the discharging member at the setting output, with a second charging current which is detected by the charging current detection unit at the time of operating the discharging member at comparison output less than the setting output. In general, the setting output of the discharging member is set to an output greater than the output at which the charging current flowing through the charging member is in a saturated state, in consideration of the occurrence of ghost, or the like. For this reason, even when the discharging member is operated at the setting output, it is difficult to determine the decrease in the discharging ability of the discharging member according to the charging current flowing through the charging member until the discharging ability of the discharging member considerably decreases. However, in the example image forming apparatus, the first charging current which is detected by the charging current detection unit at the time of operating the discharging member at the setting output, is compared with the second charging current which is detected by charging current detection unit at the time of operating the discharging member at the comparison output less than the setting output, in order to determine the decrease in the discharging ability of the discharging member in an early stage.

In the example image forming apparatus described above, the performance determination unit may determine the decrease in the discharging ability of the discharging member by comparing a third charging current which is detected by the charging current detection unit at the time of operating the discharging member, with a fourth charging current which is detected by the charging current detection unit at the time of operating the exposure member. When the discharging ability of the discharging member decreases, the charging current at the time of operating the discharging member decreases, but the charging current at the time of operating the exposure member is rarely changed. Therefore, the third charging current which is detected by the charging current detection unit at the time of operating the discharging member, is compared with the fourth charging current which is detected by the charging current detection unit at the time of operating the exposure member, in order to determine the decrease in the discharging ability of the discharging member.

The example image forming apparatus may further include a display device, and the performance determination unit may display an alarm on the display device when it is determined that the discharging ability of the discharging member decreases. When it is determined that the discharging ability of the discharging member decreases, the alarm is displayed on the display device, and thus, it is possible to urge the user to wipe out the discharging member, stop printing, or the like.

The example image forming apparatus may further include a wiping member for wiping out the discharging member, and the performance determination unit may wipe off the discharging member by the wiping member when it is determined that the discharging ability of the discharging member decreases. When it is determined that the discharging ability of the discharging member decreases, the discharging member is wiped out by the wiping member, and thus, it is possible to reactivate (or restore) the discharging ability of the discharging member before the discharging ability of the discharging member considerably decreases.

In the example image forming apparatus, the performance determination unit may determine the decrease in the discharging ability of the discharging member by storing a charging current which is detected by the charging current detection unit at the time of disposing a process cartridge including the photoreceptor, the charging member, and the discharging member, as a standard charging current, and then, by comparing the charging current which is detected by the charging current detection unit, with the standard charging current. The stored standard charging current is compared with the charging current which is detected by the charging current detection unit, in order to determine the decrease in the discharging ability of the discharging member.

The performance determination unit may determine the decrease in the discharging ability of the discharging member when a temperature or humidity in an environment where the image forming apparatus is placed, is changed. In this case, the performance determination unit may determine the decrease in the discharging ability of the discharging member when the temperature is changed by 2°C to 3°C, and the humidity is changed by 5%. The discharging ability of the discharging member is easily affected by the temperature or the humidity. Therefore, the decrease in the discharging ability of the discharging member may be determined when the temperature or the humidity in the environment where the image forming apparatus is placed, is changed.

The performance determination unit may determine the decrease in the discharging ability of the discharging member when printing having a printing rate of greater than or equal to a predetermined value is continuously performed a predetermined number of times (e.g. performed substantially consecutively a predetermined number of times). In this case, the performance determination unit may determine the decrease in the discharging ability of the discharging member when printing having a printing rate of greater than or equal to 20% is continuously performed 200 times (e.g. performed 200 times substantially consecutively). When the printing having a printing rate of greater than or equal to a predetermined value is continuously performed a predetermined number of times (e.g. performed substantially consecutively a predetermined number of times), the discharging ability of the discharging member tends to easily decrease. Therefore, the decrease in the discharging ability of the discharging member may be determined when the printing having a printing rate of greater than or equal to predetermined value is continuously or consecutively performed a predetermined number of times.

Accordingly, it is possible to detect a decrease in discharging ability of a discharging member by a simple method/manner and with a relatively simple structural configuration.

It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail.

List of Reference Numbers

1, 1A, 1B, 1C: image forming apparatus, 2: photoreceptor, 3: charging member, 4: charging power source, 5: exposure member, 6: development member, 7: transfer member, 8: transfer body, 9: discharging member, 10: cleaning member, 11: charging current detection unit, current detector, 13: display device, 14: wiping member, 20, 21: performance determination unit.

Claims

An image forming apparatus comprising:

a photoreceptor;

a charging member to charge the photoreceptor;

an exposure member to form an electrostatic latent image on the photoreceptor by exposing the photoreceptor;

a development member to develop the electrostatic latent image formed on the photoreceptor;

a transfer member to transfer an image of the electrostatic latent image to a transfer body;

a discharging member to remove the electrostatic latent image from the photoreceptor, by irradiating the photoreceptor with discharging light, wherein the discharging light is set to a setting output;

a current detector to detect a charging current flowing through the charging member; and

a controller to determine a decrease in discharging ability of the discharging member, based on the charging current detected by the current detector.
The image forming apparatus according to claim 1,

the current detector to detect a first charging current at a time of operating the discharging member at the setting output, and to detect a second charging current at a time of operating the discharging member at a comparison output, wherein the comparison output is less than the setting output, and

the controller to determine the decrease in the discharging ability of the discharging member by comparing the first charging current with the second charging current.
The image forming apparatus according to claim 1,

the current detector to detect a third charging current at a time of operating the discharging member, and to detect a fourth charging current at a time of operating the exposure member, and

the controller to determine the decrease in the discharging ability of the discharging member by comparing the third charging current with the fourth charging current.
The image forming apparatus according to claim 1, further comprising:

a display device to display an alarm when the controller determines that the discharging ability of the discharging member decreases.
The image forming apparatus according to claim 1, further comprising:

a wiping member to wipe the discharging member when the controller determines the decrease in the discharging ability of the discharging member.
The image forming apparatus according to claim 1,

the current detector to detect a standard charging current at a time of disposing a process cartridge including the photoreceptor, the charging member, and the discharging member, and

the controller to store the standard charging current, and to determine the decrease in the discharging ability of the discharging member by comparing the charging current with the standard charging current.
The image forming apparatus according to claim 1,

the controller to determine the decrease in the discharging ability of the discharging member when a temperature or humidity in an environment where the image forming apparatus is located, is changed.
The image forming apparatus according to claim 7,

the controller to determine the decrease in the discharging ability of the discharging member when the temperature is changed by 2°C to 3°C, or the humidity is changed by 5%.
The image forming apparatus according to claim 1,

the controller to determine the decrease in the discharging ability of the discharging member when printing having a printing rate of greater than or equal to a predetermined value is continuously performed a predetermined number of times.
The image forming apparatus according to claim 9,

wherein the predetermined value associated with the printing rate is 20%, and the predetermined number of times of continuously performing printing is 200 times.
An image forming apparatus comprising:

a photoreceptor to carry an electrostatic latent image;

a charger to charge the photoreceptor;

a discharger to discharge the photoreceptor after an image of the electrostatic latent image has been transferred to a transfer body;

a current detector to detect a charging current flowing through the charger;

a controller to determine a decrease in discharging performance of the discharger, based on the charging current detected by the current detector; and

a wiping member to wipe the discharger when the controller determines the decrease in the discharging performance of the discharger.
A method comprising:

charging a photoreceptor by means of a charger;

transferring an electrostatic latent image from the photoreceptor to a transfer body;

discharging the photoreceptor by means of a discharger;

detecting a charging current flowing through the charger;

determining a decrease in a discharging performance of the discharger, based on the charging current detected by the current detector; and

wiping the discharger in response to determining the decrease in the discharging performance of the discharger.
The method accordingly to claim 12,

wherein detecting the charging current comprises: detecting a setting-output charging current at a time of operating the discharger at a setting output; and detecting a comparison-output charging current at a time of operating the discharger at a comparison output, wherein the comparison output is less than the setting output, and

wherein determining the decrease in the discharging performance comprises comparing the setting-output charging current with the comparison-output charging current.
The method accordingly to claim 12,

wherein detecting the charging current comprises: detecting a discharger-operation charging current at a time of operating the discharger; and detecting an exposure-operation charging current at a time of operating an exposure member to expose the photoreceptor to form the electrostatic latent image on the photoreceptor, and

wherein determining the decrease in the discharging performance of the discharger comprises comparing the discharger-operation charging current with the exposure-operation charging current.
The method accordingly to claim 12, further comprising:

detecting a standard charging current at a time of disposing a process cartridge including the photoreceptor, the charger, and the discharger,

wherein determining the decrease in the discharging performance of the discharger comprises comparing the charging current with the standard charging current.