JP2016157074A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: when an optimal process condition is set to a component appeared to be deteriorated so as to reuse the component, the state of deterioration of a photoreceptor and a charging member constituting a process cartridge cannot be accurately grasped, and an optimal process condition cannot be set individually to the photoreceptor and the charging member.SOLUTION: In an initial rotation operation period that is a non-image forming period, an image forming apparatus determines the state of deterioration of a photoreceptor drum 1 and a charging roller 2 according to the state of a current flowing in the photoreceptor drum 1 via the charging roller 2 when an application bias voltage is applied, and sets a process condition according to the state of deterioration of both components so as to set an optimal process condition according to the state of deterioration of the components.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an electrophotographic image forming apparatus.

  An image forming apparatus used for a copying machine, a fax machine, or the like forms a latent image by selectively exposing a uniformly charged electrophotographic photosensitive member according to image information. The latent image is visualized with toner, and the toner image is transferred to a recording medium to perform image recording. In such an apparatus, the electrophotographic photosensitive member and process means such as a charging unit and a cleaning unit that act on the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge can be attached to and detached from the apparatus main body. Is adopted. According to this method, when the photosensitive drum accommodated in the cartridge reaches the end of its life, the user can easily perform maintenance by replacing the cartridge.

  However, in recent years, recycling of such cartridges has been promoted from the viewpoint of environmental protection, etc., but most of them, the image forming apparatus as a whole is selected and reused only for parts that can maintain the same quality as new products. The reuse of parts whose performance deteriorates due to use has not been promoted. It is necessary to take appropriate measures according to the usage status of each part so that image defects do not occur when parts with degraded performance are reused. This is because there is a problem in that no appropriate measures cannot be taken because there is no means for accurately identifying the.

  In order to solve this problem, in an image forming apparatus that includes an apparatus main body and a process cartridge that is detachably attached to the apparatus main body, recycling history information, such as the number of reuses, is stored in a memory element for parts constituting the process cartridge. For example, a method is used in which information is recorded on an information recording medium such as the like, and the information recording medium is disposed on the outer surface of the process cartridge (see Patent Document 1). In this case, at the time of image formation, the recycle recording information in the information recording medium is read by the reading unit, and the development bias condition is controlled to an optimum value according to the read number of reuses. Quality is equivalent to new.

JP-A-9-120249

  As described above, according to the proposal of Patent Document 1, it is possible to recycle components that have deteriorated performance based on the recycling history information such as the number of reuses by setting optimum development bias conditions. It has become.

  However, in the image forming apparatus disclosed in Patent Document 1, depending on the environment and conditions in which the process cartridge is used, there is a case where the deterioration of the parts is small or the deterioration is progressing even in the same number of times of reuse. If the process conditions are set according to the deterioration state of the part determined based on the number of times, the life of the photosensitive drum is shortened or charged in a part in a deterioration state different from the deterioration state of the part determined based on the number of reuses. There is a possibility of increasing the risk of defects such as defects.

  The present invention has been made in view of the problems existing in the prior art, and an image forming apparatus capable of setting optimum process conditions according to the state of each component in each component constituting the process cartridge. The purpose is to provide.

  In order to achieve the above object, an image forming apparatus according to the present invention includes an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, and a voltage applying unit for applying a voltage to the charging unit. A current state detecting means for detecting a current state flowing through the electrophotographic photosensitive member via the charging means when a voltage is applied by the voltage applying means, and according to a detection result of the current state detecting means. And a control unit for setting process conditions.

  Furthermore, another image forming apparatus according to the present invention includes an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a voltage applying unit for applying a voltage to the charging unit, and the voltage A current condition detecting means for detecting a current state flowing in the electrophotographic photosensitive member or the charging means when a voltage is applied by the applying means, and a process condition is set according to a detection result of the current state detecting means. And a control unit.

  Furthermore, another image forming apparatus according to the present invention includes an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a voltage applying unit for applying a voltage to the charging unit, and the voltage A current state detecting unit for detecting a current state flowing through the electrophotographic photosensitive member via the charging unit when a voltage is applied by the applying unit; and a humidity detecting unit for detecting the humidity in the image forming apparatus; And a controller that sets process conditions according to the humidity detected by the absolute humidity detector and the detection result of the current state detector.

  Furthermore, another image forming apparatus according to the present invention includes an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a voltage applying unit for applying a voltage to the charging unit, and the voltage A current state detection unit for detecting a current state flowing through the electrophotographic photosensitive member and the charging unit when a voltage is applied by the application unit; a humidity detection unit for detecting humidity in the image forming apparatus; A controller configured to set process conditions according to the humidity detected by the humidity detector and the detection result of the current state detector;

  According to the image forming apparatus of the present invention, the process conditions of the image forming apparatus can be set according to the state of each component constituting the process cartridge.

Schematic configuration around the process cartridge Layer structure of photoconductor Block diagram of charging bias application system Relationship between applied voltage and amount of alternating current in the first embodiment Flow chart showing the control of the first embodiment Component status determination table for each detected current value in the first embodiment Diagram of applied voltage and AC current for each environment Flowchart showing the control of the second embodiment Flowchart showing the flow B in FIG. Component status determination table for each detected current value when the absolute humidity in the second embodiment is equal to or greater than the absolute moisture content reference value

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments do not limit the present invention according to the claims, and all combinations of features described in the present embodiments are not necessarily essential to the solution means of the present invention. .

(First embodiment)
FIG. 1 is a schematic configuration diagram around a process cartridge that is detachably provided in the image forming apparatus according to the present exemplary embodiment. Here, the process cartridge is a cartridge having an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member integrally in a cartridge frame and is detachably attached to the image forming apparatus by a user. Say. The process means is a charging means for charging the electrophotographic photosensitive member (for example, a charging roller, a charging brush, a corona charger), and developing the electrostatic latent image formed on the electrophotographic photosensitive member using a developer. Developing means (e.g., developing roller, developing brush, etc.) and cleaning means (e.g., removing developer remaining on the electrophotographic photosensitive member after the developer image is transferred from the electrophotographic photosensitive member to the recording medium). , Cleaning blades, cleaning brushes, etc.).

  The process cartridge includes a cartridge having at least one of the electrophotographic photosensitive member and the process means. The recording medium is an image on which an image is formed by an image forming apparatus, and includes, for example, paper, a sheet, an OHP sheet, a cloth, and the like.

  The image forming apparatus according to the present embodiment is a laser beam image forming apparatus that uses a transfer type electrophotographic process, a contact charging method, and a reversal development method, and can change the image forming process speed and the image forming pixel density.

  1 is a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum). The photosensitive drum 1 is a negatively charged organic photoconductor called OPC (Organic Photo Conductors), and is normally driven to rotate counterclockwise as indicated by an arrow about a central support shaft during image formation.

FIG. 2 is a layer configuration diagram of the photosensitive drum 1 of FIG. The photosensitive drum 1 includes, in order from the center, a surface of an aluminum cylinder (conductive drum base) 1a, an undercoat layer 1b that suppresses interference of light and improves adhesion of an upper layer, a photocharge generation layer 1c, a surface The charge transport layer 1d having a resistance value of about 10 ¹⁵ Ω · cm is applied in three layers.

  Reference numeral 2 shown in FIG. 1 denotes a contact charging device (contact charger) as charging means for uniformly charging the peripheral surface of the photosensitive drum 1, and a charging roller (roller charger) is used in this embodiment.

The charging roller 2 is configured such that both ends of a core metal (support member) 2a are rotatably held by bearing members (not shown) and are urged toward the photosensitive drum 1 by a pressing spring 2e. The drum 1 is pressed against the surface of the drum 1 with a predetermined pressing force, and rotates following the rotation of the photosensitive drum 1. A pressure contact position of the charging roller 2 with respect to the photosensitive drum 1 is a charging position (charging nip position ) a.

  The charging member 2a of the charging roller 2 is uniformly contact-charged so that the peripheral surface of the photosensitive drum 1 becomes negative by applying a charging bias voltage (applied bias voltage) of a predetermined condition from the power source S1. Is done. The configuration of the charging roller 2 will be described later.

  Reference numeral 3 shown in FIG. 1 denotes an exposure apparatus as information writing means for forming an electrostatic latent image on the charged photosensitive drum 1, and in this embodiment, a laser beam scanner using a semiconductor laser.

  The exposure device 3 outputs a laser beam modulated in accordance with an image signal sent from the image reading device (not shown) to the image forming device side, and the uniform charging processing surface of the photosensitive drum 1 is exposed at the exposure position b. Laser scanning exposure L (image scanning exposure) is performed. By this laser scanning exposure L, the potential irradiated with the laser beam on the surface of the photosensitive drum 1 is lowered. As a result, electrostatic latent images corresponding to the scanned and exposed image information are sequentially formed on the photosensitive drum 1.

  Reference numeral 4 shown in FIG. 1 denotes a developing means for supplying a developer (toner) to the electrostatic latent image on the photosensitive drum 1 to visualize the electrostatic latent image. In this embodiment, a jumping developing device (developer) ) Is used. The electrostatic latent image formed on the surface of the photosensitive drum 1 is reversely developed with the one-component magnetic toner (negative toner) negatively charged by the developing device 4.

  In the developing device 4, 4a is a developing container, 4b is a non-magnetic developing sleeve, and this developing sleeve 4b is rotatable in the developing container 4a so that a part of its outer peripheral surface is exposed to the outside of the developing container 4a. It is arranged. A magnet roller 4c is fixedly inserted in the developing sleeve 4b in a non-rotating manner, 4d is a developer coating blade, 4e is a one-component magnetic toner as a developer contained in the developing container 4a, and S2 is for the developing sleeve 4b. A developing bias application power source.

  The one-component magnetic toner coated as a thin layer on the surface of the developing sleeve 4b rotating in the counterclockwise direction indicated by the arrow and transported to the developing position c is applied to the photosensitive drum 1 by the electric field due to the developing bias to the electrostatic latent image. The electrostatic latent image is developed as a toner image by correspondingly selectively attaching. In the present embodiment, toner adheres to the exposed bright portion (exposed portion) of the photosensitive drum 1 and the electrostatic latent image is reversely developed.

  The developer thin layer on the developing sleeve 4b that has passed through the developing position c without adhering to the photosensitive drum 1 is returned to the developer reservoir in the developing container 4a as the developing sleeve 4b rotates.

  A transfer device 5 uses a transfer roller in this embodiment. The transfer roller 5 is pressed against the photosensitive drum 1 with a predetermined pressing force, and the pressure nip position is a transfer position d. The recording medium P is fed to the transfer position d from a paper feeding mechanism unit (not shown).

  The recording medium P fed to the transfer position d is nipped and conveyed between the rotating photosensitive drum 1 and the transfer roller 5, and during that time, the transfer roller 5 has a normal charging polarity of toner from the transfer bias application power source S3. By applying a positive transfer bias having a polarity opposite to the negative polarity, the toner image developed on the photosensitive drum 1 is electrostatically transferred onto the surface of the recording medium P that is nipped and conveyed at the transfer position d. To go.

  The recording medium P that has received the transfer of the toner image through the transfer position d is separated from the photosensitive drum 1 and conveyed to a fixing device 6 (for example, a heat roller fixing device or a fixing device) to undergo a toner image fixing process. Output as an image formed product (print, copy).

  A cleaning device 7 serves as a cleaning unit, and removes transfer residual toner by bringing a cleaning blade 7a into contact with the surface of the photosensitive drum 1 after the transfer of the toner image to the recording medium P. e is a contact portion of the cleaning blade 7a with the photosensitive drum 1.

  Next, an operation sequence of the image forming apparatus in the present embodiment will be described. The main sequence includes an initial rotation operation (pre-multi-rotation process), a print preparation rotation operation (pre-rotation process), a printing process, a transfer process, an inter-sheet process, and a post-rotation operation.

  First, the initial rotation operation (pre-multi-rotation process) will be described. The initial rotation operation (pre-multi-rotation process) is a start-up operation period (start-up operation period, warming period) at the start-up of the image forming apparatus, and the photosensitive drum 1 is driven to rotate by turning on the power switch. Then, a preparatory operation for a predetermined process device, such as raising the fixing device to a predetermined temperature, is performed. During the initial rotation operation period, the states of the photosensitive drum 1 and the charging roller 2 are detected. A method for detecting the state will be described later.

  Next, the print preparation rotation operation (pre-rotation process) will be described. The print preparation rotation operation (pre-rotation process) is a preparation rotation operation period before image formation from when a print signal is input until the image formation (printing) process operation is actually performed. When a print signal is input to the input signal, it is executed following the initial rotation operation.

  When the print signal is not input, the drive of the main motor is temporarily stopped after the initial rotation operation is completed, and the rotation of the photosensitive drum 1 is stopped. The image forming apparatus is in a standby (standby) state until the print signal is input. Kept. When a print signal is input, a print preparation rotation operation is executed.

  Next, the printing process (image forming process, image forming process) will be described. The printing process is a transfer in which a toner image formed on the photosensitive drum 1 is transferred to the recording medium P by executing an image forming process including a charging process for the photosensitive drum 1 when a predetermined printing preparation rotation operation is completed. In this step, the toner image is fixed by the fixing device, and the image formed product is printed out. In the case of continuous printing (continuous printing) mode, the above printing process is repeated for a predetermined set number of prints n.

  Next, the inter-sheet process will be described. The inter-sheet process is a continuous printing mode at a transfer position after the trailing edge of the recording medium P passes the transfer position d and until the leading edge of the next recording medium P ′ reaches the transfer position d. This is the non-sheet passing state period of the recording paper.

  Next, the post-rotation operation will be described. The post-rotation operation is a period in which the photosensitive drum 1 is rotated by continuing to drive the main motor for a while even after the printing process of the last recording medium P is completed.

  When the predetermined post-rotation operation is completed, the drive of the main motor is stopped, the rotation of the photosensitive drum 1 is stopped, and the image forming apparatus is kept in a standby state until the next print start signal is input. . In the case of printing only one sheet, after the printing is finished, the image forming apparatus goes into a standby state through a post-rotation operation. When a print start signal is input in the standby state, the image forming apparatus proceeds to a pre-rotation process.

  As for these processes, the printing process is a process at the time of image formation, and the initial rotation operation, the print preparation rotation operation, the inter-sheet process, and the post-rotation operation are processes at the time of non-image formation.

  Next, the charging roller 2 will be described in detail with reference to FIG. As shown in FIG. 1, the charging roller 2 as a contact charging member has a three-layer structure in which a lower layer 2b, an intermediate layer 2c, and a surface layer 2d are sequentially laminated from the bottom around a core metal 2a. The lower layer 2b is a foamed sponge layer for reducing charging noise, the intermediate layer 2c is a conductive layer for obtaining a uniform resistance as the entire charging roller 2, and the surface layer 2d is formed on the photosensitive drum 1 such as a pinhole. This is a protective layer provided to prevent leakage due to defects.

  FIG. 3 is a block circuit diagram of a charging bias application system for the charging roller 2. A charging bias application power source S1 that is a voltage application means for the charging roller 2 includes a direct current (DC) power source and an alternating current (AC) power source, and a predetermined superposition in which an alternating voltage of frequency f is superimposed on the direct current voltage from the power source S1. When the voltage (bias voltage Vdc + Vac) is applied to the charging roller 2 through the core metal 2a, the rotating photosensitive drum 1 is charged to a predetermined potential.

  Reference numeral 13 denotes a control circuit that controls on / off of the DC power supply 11 and the AC power supply 12 of the power supply S1 to control the charging roller 2 to apply a superimposed voltage in which both a DC voltage and an AC voltage are superimposed, and a DC power supply. 11 has a function of controlling a DC voltage value applied from 11 to the charging roller 2 and a peak-to-peak voltage value of AC voltage applied from the AC power source 12 to the charging roller 2.

  Reference numeral 14 denotes an AC current value measuring circuit as means for measuring the AC current effective value X flowing through the photosensitive drum 1 via the charging roller 2. The AC current value measurement circuit 14 outputs the measured AC current value information to the control circuit 13.

  Reference numeral 15 denotes an environment sensor (temperature sensor and humidity sensor) as means for detecting the environment in which the image forming apparatus is installed. The environmental sensor 15 outputs the detected environmental information to the control circuit 13.

  Then, the control circuit 13 uses the AC current value information output from the AC current value measurement circuit 14 and the environmental information output from the environmental sensor 15 to appropriately determine the AC voltage applied to the charging roller 2 in the charging process in the printing process. Obtain the peak-to-peak voltage value.

  Next, a method for controlling the AC voltage applied to the charging roller 2 during printing will be described. In the present embodiment, an AC constant current control system that controls an alternating current value that flows by controlling an alternating voltage applied to the charging member is employed.

  According to the AC constant current control system, in the L / L environment (low temperature and low humidity environment) in which the material resistance increases, the AC peak voltage is increased, and conversely, the H / H environment (high temperature) in which the material resistance decreases. Since the peak-to-peak voltage value can be lowered in a high humidity environment), it is possible to suppress increase / decrease in discharge as compared with an AC constant voltage control method in which the applied AC voltage is controlled to be always constant.

  Here, the charging roller 2 is not necessarily in contact with the surface of the photosensitive drum 1, and even a dischargeable region determined by the voltage between the gap and the correction Paschen curve is reliably provided between the charging roller 2 and the photosensitive drum 1. If guaranteed, for example, a space (gap) of several tens of μm may be provided in close proximity to each other (proximity charging). In this embodiment, the proximity charging is also included in the category of contact charging. And

  Next, the state detection of the photosensitive drum 1 and the charging roller 2 will be described.

  FIG. 4 is a graph showing the transition of the amount of current flowing into the photosensitive drum 1 via the charging roller 2 with respect to the applied voltage when the absolute humidity is 6.0. Z2 indicates a region where the deterioration of the photosensitive drum 1 and the charging roller 2 is equivalent, and Z3 indicates a region where the photosensitive drum 1 is closer to a newer state than the charging roller 2. ing. The reason why the relationship between the applied voltage and the amount of current changes as shown in FIG. 5 and the control of the applied bias voltage with respect thereto will be described.

  As the number of operations increases as a characteristic of the photosensitive drum 1 alone, the charge transport layer 1d is consumed and the thickness is reduced. The electrostatic capacity increases as the surface area of the layer is larger and the thickness is thinner, so that the electrostatic capacity of the photosensitive drum 1 itself increases.

  Further, as the characteristics of the charging roller 2 alone, as the number of operations increases, the surface resistance increases due to adhesion of an external additive, which is a high resistance material contained in the toner, to the surface layer 2d of the charging roller 2.

  Based on these characteristics, when both the photosensitive drum 1 and the charging roller 2 are in the same deterioration state, when the charging roller 2 is deteriorated more than the photosensitive drum 1, the photosensitive drum 1 is more deteriorated than the charging roller 2. The four patterns in the case where the direction is deteriorated and the abnormality occurs in the photosensitive unit will be specifically described.

  First, when both the photosensitive drum 1 and the charging roller 2 are in the same deterioration state, control is performed so as to apply the optimum applied bias voltage in the normal state.

  Next, the case where the charging roller 2 is more deteriorated than the photosensitive drum 1 will be described. In this case, the surface layer 2d is thick in a state close to that of a new product, and therefore the electrostatic resistance is small and the surface resistance is increased due to contamination of the external additive and the photosensitive drum 1 which is in a state where current does not flow easily. The charging roller 2 that is in a state where it is difficult for current to flow is combined. In this state, the amount of current flowing to the photosensitive drum 1 via the charging roller 2 with respect to the applied voltage is reduced compared to the case where both the photosensitive drum 1 and the charging roller 2 have the same deterioration level, and charging failure, etc. Therefore, it is necessary to apply a higher applied bias voltage than usual because the amount of current required for not producing a defective image increases.

  Next, a case where the photosensitive drum 1 is in a deteriorated state as compared with the charging roller 2 will be described. In this case, the surface layer 2d is made thinner and the capacitance is increased, so that the current easily flows and the resistance increase due to contamination of the external additive has not occurred. Is in a state where the charging roller 2 is in a state where it is easy to flow. In this state, the value of the current flowing through the photosensitive drum 1 via the charging roller 2 with respect to the applied voltage increases as compared with the case where both the photosensitive drum 1 and the charging roller 2 have the same deterioration level, and charging failure, etc. Therefore, it is necessary to apply an applied bias voltage lower than usual because the amount of current required for not producing a defective image is reduced.

  Next, a case where an abnormality has occurred in the photoreceptor unit will be described. If the amount of current flowing through the photosensitive drum 1 via the charging roller 2 with respect to an arbitrary applied voltage is outside the assumed range, the overall resistance or capacity of the photosensitive unit is too high, or the entire Abnormalities such as resistance and capacitance are too low.

  Examples of the state in which the overall resistance or capacity of the photosensitive unit is detected unexpectedly high include an installation error of the photosensitive unit or a case where it is not installed in the first place. If the printing operation is started with the photoconductor unit not installed, the toner that should originally adhere to the photoconductor unit may cause a failure such as scattering in the apparatus. The state in which the overall resistance or capacity of the photoconductor unit is detected unexpectedly low includes an abnormal component assembly state in addition to an installation error of the photoconductor unit. In this case, the current tends to flow abnormally, and in some cases, it causes a main body failure such as a current leak to the main body.

  Since the above cases are conceivable, if the amount of current flowing through the photosensitive member via the charging member with respect to an arbitrary applied bias voltage is outside the assumed range, it is determined that there is an abnormality and an error display is displayed. Therefore, it is necessary to prevent a malfunction by shifting to a non-printable state.

  In the present embodiment, the controller 13 detects the states of the photosensitive drum 1 and the charging roller 2 during the initial rotation operation period, and changes the control of the applied bias according to the states. Further, the applied bias voltage in the present embodiment is a superimposed voltage obtained by superimposing an alternating voltage having a frequency f on a direct voltage.

  FIG. 5 is a flowchart showing the operation of the control circuit 13 in the present embodiment shown in FIG. 3, and FIG. 6 is a determination table based on the alternating current value detected in an environment where the absolute humidity H is 6.0 and the flowchart of FIG. It is a table | surface of the electric current value equivalent to the symbol of. In the flowchart of FIG. 5, the control of the applied bias voltage is started after the initial rotation operation is started.

  In S101, the effective value of the alternating current that flows to the photosensitive drum 1 via the charging roller 2 when a superimposed voltage (1.0 kV in this embodiment) obtained by superimposing both a predetermined direct current voltage and an alternating voltage is applied to the charging roller 2. X is measured by the alternating current value measuring circuit 14 shown in FIG.

  In S102, it is determined whether or not the AC current effective value X measured in S101 is within a range of 830 μA ≧ X> 675 μA. If it is within the range, it is determined in S103 that the photosensitive drum 1 and the charging roller 2 are in the same deterioration state, and in S104, the charging bias application power source S1 shown in FIG. 3 is the optimum application bias voltage in this case. Apply 1.6 kV.

  If it is not in the range of 830 μA ≧ X> 675 μA in S102, it is determined in S105 whether the AC current effective value X is in the range of 990 μA ≧ X> 830 μA. If it is within the range, it is determined in S106 that the photosensitive drum 1 is more deteriorated than the charging roller 2.

  In this case, the AC current effective value X tends to increase, and the amount of current required to prevent a defective image such as a charging failure from being reduced is reduced. In S107, both the photosensitive drum 1 and the charging roller 2 are equivalent. Control is performed so that the applied bias voltage S1 shown in FIG. 3 applies an applied bias voltage of 1.55 kV, which is lower than the applied bias voltage in the deteriorated state.

  If it is not in the range of 990 μA ≧ X> 830 μA in S105, it is determined in S108 whether the AC current effective value X is in the range of 675 μA ≧ X> 540 μA. If it is within the range, it is determined in S109 that the charging roller 2 is more deteriorated than the photosensitive drum 1.

  In this case, the AC current effective value X tends to decrease, and the amount of current necessary to prevent a defective image such as a charging failure from increasing increases. Therefore, in S110, both the photosensitive drum 1 and the charging roller 2 are equal. Control is performed so that the applied bias voltage S1 shown in FIG. 3 applies an applied bias voltage of 1.65 kV, which is higher than the applied bias voltage in the deteriorated state.

  If the AC current effective value X is outside the range of 675 μA ≧ X> 540 μA in S108, it is determined in S111 that there is an abnormality in the photosensitive unit, and an error is displayed on the display device 16 shown in FIG. 3 in S112.

  As described above, by detecting the current flowing from the charging roller 2 to the photosensitive drum 1, it is possible to determine the state of the component and set the optimum process condition according to the state.

(Second embodiment)
In the present embodiment, the controller 13 detects the states of the photosensitive drum unit 1 and the photosensitive drum 1 and the charging roller 2 during the initial rotation operation period, and in addition to the state, the environment sensor 15 shown in FIG. The flow for changing the control of the applied bias voltage is switched in consideration of the detection result.

  FIG. 7 is a graph showing the transition of the amount of current flowing into the photosensitive drum 1 via the charging roller 2 with respect to the applied bias voltage when the absolute humidity H is different. FIG. 7A shows the transition of the current amount when the absolute humidity H described in the first embodiment is 6.0, and FIG. 7B shows the transition of the current amount when the absolute humidity H is 13.0. As in the first embodiment, Z1 is a region where the charging roller 2 is closer to a new product than the photosensitive drum 1, and Z2 is a region where the deterioration degree of the photosensitive drum 1 and the charging roller 2 is equivalent. , Z3 indicates an area where the photosensitive drum 1 is closer to a newer state than the charging roller 2.

  Since the resistance value of the charging roller 2 varies according to the temperature / humidity state and the durability state, the curve of the current amount with respect to the applied voltage varies as shown in FIG. In the present embodiment, the control circuit 13 calculates the absolute humidity using the temperature / humidity data detected by the environmental sensor 15 shown in FIG. 3, and the flow for changing the control of the applied bias voltage is switched according to the result. The applied bias voltage in the present embodiment is a superimposed voltage obtained by superimposing an AC voltage having a frequency f on a DC voltage, as in the first embodiment.

  8 is a flowchart showing the operation of the control circuit 13 in this embodiment, FIG. 9 is a flowchart of the flow B in the flowchart of FIG. 8, and FIG. 10 is a determination table based on the detected current value when the absolute humidity H is 13.0. 10 is a table of current values corresponding to symbols in the flowchart of FIG. In the flowchart of FIG. 8, the control of the applied bias voltage is started after the initial rotation operation is started.

  First, in S <b> 201, the absolute humidity H guided by the environment sensor 15 and the control circuit 13 is compared with the absolute water content reference value T determined by the characteristics of the charging roller 2.

  Here, if the absolute humidity H is equal to or less than the absolute water content reference value T, the control is performed according to the normal control flow A (S101 to S112 of the control flow described in the first embodiment).

  If the absolute humidity H exceeds the absolute water content reference value T in S201, the process proceeds to the control flow B shown in FIG. 9, and both the predetermined DC voltage and AC voltage are superimposed on the charging roller 2 in S301. When the superimposed voltage (1.0 kV in this embodiment) is applied, the AC current value X flowing through the photosensitive drum 1 via the charging roller 2 at that time is measured by the AC current value measuring circuit 14 shown in FIG. .

  In S302, it is determined whether or not the AC current value X measured in S301 is within a range of 920 μA ≧ X> 750 μA. If it is within the range, it is determined in S303 that both the photosensitive drum 1 and the charging roller 2 are in the same deterioration state, and in S304, the charging bias application power source S1 shown in FIG. Apply .55 kV.

  If it is not in the range of 920 μA ≧ X> 750 μA in S302, it is determined in S305 whether the AC current value X is in the range of 1100 μA ≧ X> 920 μA. If it is within the range, it is determined in S306 that the photosensitive drum 1 is more deteriorated than the charging roller 2. In this case, since the alternating current value X tends to increase, in S307, the optimum applied bias voltage of 1.5 kV, which is lower than the applied bias voltage when both the photosensitive drum 1 and the charging roller 2 are in the same deterioration state, is determined. Is controlled so that the charging bias application power source S1 shown in FIG.

  If it is not in the range of 1100 μA ≧ X ≧ 920 μA in S305, it is determined in S308 whether the AC current value X is in the range of 750 μA ≧ X> 600 μA. If it is within the range, it is determined in S309 that the charging roller 2 is more deteriorated than the photosensitive drum 1. In this case, since the alternating current value X tends to decrease, an optimum applied bias voltage of 1.6 kV, which is higher than the applied bias voltage when both the photosensitive drum 1 and the charging roller 2 are in the same deterioration state in S310, is set. Control is performed so that the charging bias application power source S1 shown in FIG. 3 is applied.

  If the AC current value X is outside the range of 750 μA ≧ X> 600 μA in S308, it is determined in S311 that there is an abnormality in the photoconductor unit, and an error is displayed on the display device 16 shown in FIG.

  As described above, by changing the threshold value for the AC current value that flows into the photosensitive drum through the charging roller in accordance with the absolute water content or absolute humidity, it is possible to set optimum process conditions according to the state of the component. .

(Other embodiments)
In the above-described embodiments, the image forming apparatus having the process cartridge that is attachable to and detachable from the image forming apparatus main body integrally including at least the photoconductor and the charging member has been described. However, the image forming apparatus main body is not limited thereto. The present invention can also be applied to a configuration in which process means such as a charging member or the like is provided in the apparatus main body.

  In the above-described embodiment, the state of the photoconductor and the charging member is determined by detecting the state of the current flowing through the photoconductor via the charging member. However, not only the monochrome image formation but also the photoconductor. Even in an image forming apparatus that forms a multicolor image by multiple transfer using an intermediate transfer member such as a transfer drum or a transfer belt between the charging member and the charging member, the current flowing through the photosensitive member via the charging member The state of the photosensitive member and the charging member can be determined by detecting the state, or the state of the photosensitive member and the charging member can be determined by detecting the state of the current flowing through each of the photosensitive member and the charging member. The present invention can be applied to any configuration.

  In the above-described embodiment, the image forming apparatus is applied during the initial rotation operation during non-image formation. However, the present invention is not limited to this, but during other non-image formation, that is, the print preparation rotation operation period, the inter-sheet process It can also be applied during the post-rotation process.

In the above-described embodiment, the photosensitive drum 1 is provided with a charge transport layer having a surface resistance of about 10 ¹⁵ Ω · cm. However, the present invention is not limited to this, and the surface resistance is 10 ⁹ Ω · cm. To 10 ¹⁵ Ω · cm, and a direct injection charging type provided with a charge injection layer in the range of about 10 ¹⁵ Ω · cm. Even when the charge injection layer is not used, for example, the same effect can be obtained when the charge transport layer is in the above resistance range. For example, an amorphous silicon photoreceptor having a surface layer volume resistance of about 10 ¹³ Ω · cm may be used.

  Further, as the charging member having flexibility, in addition to the charging roller used in the above-described embodiment, those having shapes and materials such as fur brushes, felts, and cloths can be used.

  In the above-described embodiment, the current state flowing through the photosensitive member via the charging member is detected, and the applied bias voltage is changed as a process condition according to the detection result. As a condition, a configuration may be adopted in which the process speed when the recording medium is conveyed is changed.

  In addition to the laser scanning unit of the embodiment, the image exposure unit as the information writing unit with respect to the charged surface of the photosensitive member as the image carrier is, for example, a digital exposure unit using a solid light emitting element array such as an LED. There may be. An analog image exposure unit using a halogen lamp or a fluorescent lamp as a document illumination light source may be used. That is, it is sufficient if it can form an electrostatic latent image corresponding to image information.

Further, the toner developing method and means for the electrostatic latent image are arbitrary. A reversal development method or a regular development method may be used.
In general, the electrostatic latent image is developed by coating nonmagnetic toner with a blade or the like on a developer carrying member such as a sleeve for nonmagnetic toner, and applying this on the developer carrying member for magnetic toner. And a method of developing the electrostatic latent image by applying it in a non-contact state to the image carrier (one-component non-contact development) and a developer carrying member as described above. A method of developing the electrostatic latent image by applying the toner coated on the image bearing member in contact with the image carrier (one-component contact development) and a mixture of toner particles and a magnetic carrier as a developer (2 As a component developer), conveyed by magnetic force, applied in contact with an image carrier and developed as an electrostatic latent image (two-component contact development), and the above two-component developer as an image carrier Suitable for non-contact with the body And they are classified into four 顛 the method (two-component non-contact development) for developing the electrostatic latent image.

  Further, the transfer means is not limited to the roller transfer of the embodiment, but may be a blade transfer, a belt transfer, other contact transfer charging methods, or a non-contact transfer charging method using a corona charger.

  In the embodiment, the state of the current flowing through the charging member via the charging member is detected to detect the state of the photosensitive member and the charging member. However, the present invention is not limited to this. It is also possible to adopt a configuration in which the process condition is changed by determining the states of the photosensitive member and the charging member by comparing the detected state and comparing them based on the detection result.

In addition, the applied bias voltage in the above-described embodiment uses a superimposed voltage obtained by superimposing an alternating voltage of frequency f on a direct current voltage. It may be used. Further, only a DC voltage may be applied as the applied bias voltage, or only an AC voltage may be applied as the applied bias voltage.

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Charging roller S1 ... Charging bias application power supply 13 ... Control circuit 14 ... AC current value measurement circuit

Claims (16)

An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a voltage applying unit for applying a voltage to the charging unit, and the charging unit when a voltage is applied by the voltage applying unit. A current state detecting means for detecting a current state flowing through the electrophotographic photosensitive member via a control unit, and a control unit for setting process conditions according to a detection result of the current state detecting means. Image forming apparatus.   An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a voltage applying unit for applying a voltage to the charging unit, and the electrophotographic photosensitive member when a voltage is applied by the voltage applying unit. An image forming apparatus comprising: a current state detecting unit for detecting a current state flowing through a body or the charging unit; and a control unit for setting process conditions according to a detection result of the current state detecting unit. apparatus.   When the control unit detects a current state detected by the current state detecting unit within a first predetermined range set in advance according to the states of the electrophotographic photosensitive member and the charging unit, the charging unit and the electronic unit It is determined that the deterioration state of the photographic photoconductor is equivalent, and a detection result of the current state by the current state detection unit is a second predetermined value set in advance according to the state of the electrophotographic photoconductor and the charging unit. If it is within the range, it is determined that the charging unit is in a state of being deteriorated more than the electrophotographic photosensitive member, and the detection result of the current state by the current state detecting unit is the electrophotographic photosensitive member and the electrophotographic photosensitive member. The electrophotographic photosensitive member is determined to be in a state of being deteriorated more than the charging unit when the third predetermined range is set in advance according to the state of the charging unit. Or the image forming apparatus according to any one of claims 2   If the detection result of the current state by the current state detection means is a fourth predetermined range different from the first predetermined range, the second predetermined range, and the third predetermined range, the control unit generates an error. The image forming apparatus according to claim 3, wherein:   The control unit compares the current state of the electrophotographic photosensitive member detected by the current state detection unit with the current state of the charging unit detected by the current state detection unit, and compares the current state of the charging unit detected by the current state detection unit. The image forming apparatus according to claim 2, wherein the deterioration state of at least one of the means is determined. The image forming apparatus according to claim 3, wherein the control unit changes an applied bias value applied to the charging unit according to the determination result. The image according to any one of claims 1 to 5, wherein the control unit changes an applied bias value applied to the charging unit in accordance with a detection result of the current state detection unit. Forming equipment.   An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a voltage applying unit for applying a voltage to the charging unit, and the charging unit when a voltage is applied by the voltage applying unit. Current state detecting means for detecting a current state flowing through the electrophotographic photosensitive member via the above, humidity detecting means for detecting the humidity in the image forming apparatus, humidity detected by the absolute humidity detecting means and the current An image forming apparatus comprising: a control unit that sets a process condition according to a detection result of the state detection unit.   An electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a voltage applying unit for applying a voltage to the charging unit, and the electrophotographic photosensitive member when a voltage is applied by the voltage applying unit. A current state detecting means for detecting a current state flowing through the body and the charging means, a humidity detecting means for detecting the humidity in the image forming apparatus, the humidity detected by the humidity detecting means and the current state detecting means An image forming apparatus comprising: a control unit configured to set a process condition according to the detection result.   When the control unit detects a current state detected by the current state detecting unit within a first predetermined range set in advance according to the states of the electrophotographic photosensitive member and the charging unit, the charging unit and the electronic unit It is determined that the deterioration state of the photographic photoconductor is equivalent, and a detection result of the current state by the current state detection unit is a second predetermined value set in advance according to the state of the electrophotographic photoconductor and the charging unit. If it is within the range, it is determined that the charging unit is in a state of being deteriorated more than the electrophotographic photosensitive member, and the detection result of the current state by the current state detecting unit is the electrophotographic photosensitive member and the electrophotographic photosensitive member. The electrophotographic photosensitive member is determined to be in a state of being deteriorated more than the charging unit when the third predetermined range is set in advance according to the state of the charging unit. Or the image forming apparatus according to any one of claims 9. Absolute humidity calculating means for calculating an absolute humidity based on the humidity detected by the humidity detecting means, the control unit, according to the absolute humidity calculated by the absolute humidity calculating means, the first predetermined range, The image forming apparatus according to claim 10, wherein at least one of the second predetermined range and the third predetermined range is changed.   When the detection result of the current state by the current state detection means is a fourth predetermined range different from the first predetermined range, the second predetermined range, and the third predetermined range, the control unit The image forming apparatus according to claim 10, wherein an error is determined.   The control unit compares the current state of the electrophotographic photosensitive member detected by the current state detection unit with the current state of the charging unit detected by the current state detection unit, and compares the current state of the charging unit detected by the current state detection unit. The image forming apparatus according to claim 9, wherein the deterioration state of at least one of the means is determined. 14. The image formation according to claim 10, wherein the control unit changes an applied bias value applied to the charging unit by the control unit according to the determination result. apparatus. The applied bias value applied to the charging unit by the control unit is changed according to a detection result of a current state by the current state detecting unit. Image forming apparatus.   The image forming apparatus is an image forming apparatus having a process cartridge including at least the electrophotographic photosensitive member and the charging unit, and the process cartridge is detachably provided in the image forming apparatus. The image forming apparatus according to any one of claims 1 to 15.

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