JP2007140178A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic image forming apparatus with a simple configuration that has a discharge mechanism capable of properly discharging even in places of different environments. <P>SOLUTION: In the image forming apparatus, a discharge control means is freely switchable between a regular discharge mode in which a discharge processing is performed such that while the output of a discharging power source means is controlled, a discharger discharges and an adjusted discharge mode in which a discharge adjustment processing is performed such that the control information of a discharge control means for performing the discharge processing in the regular discharge mode is adjusted. In the discharge adjustment processing, a discharge environmental index EnvLv is set based on control information Icc about a target charging output condition for a charging power source means adjusted in a charging adjustment process. Control information V1m, I2m, and V3m about a target discharge output condition for the discharging power source means is adjusted based on the discharge environment index EnvLv. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image carrier using a photoconductor, a charge state detecting means for detecting a charged state of the surface of the image carrier, and charging the image carrier by a charging process in an image forming process using an electrophotographic method. And a discharge mechanism that performs air discharge in a process other than the charging process. The charging mechanism causes air discharge between the image carrier and the surface of the image carrier. Charging means for charging, charging power supply means for applying a high voltage to the charging means, and charging for controlling the output of the charging power supply means so that the charging power supply means is in a preset target charging output state. And a plurality of discharge power supplies for applying a high voltage to each of the discharge devices, wherein the discharge mechanism is disposed in the vicinity of the image carrier and discharges in the air. And a power supply means for discharging And a discharge control means for controlling the output of the discharge power supply means so as to be in a preset target discharge output state, and the charge control means is configured to receive the image formation command when the charge power supply means is provided. A normal charging mode in which a charging process for charging the surface of the image carrier with the charging means is controlled by the charging unit, and a charge adjustment for adjusting control information when the charging process is performed in the normal charging mode The charge adjustment processing is configured to be switchable to an adjustment charging mode for performing processing, and when the output of the charging power supply means is controlled by the charging processing, the surface of the image carrier is in a target charging state. In this regard, the present invention relates to an image forming apparatus using an electrophotographic system configured to adjust control information about the target charge output state based on detection information of the charge state detection means. That.

The image forming apparatus employs a contact charging system composed of a charging roller or a charging brush disposed in a state where the charging means is in contact with the image carrier (for example, see Patent Document 1), or charging. There is one that employs a non-contact charging system constituted by a corona discharger such as a corotron or a scorotron that is disposed in a state where the means is opposed to each other in the vicinity of the image carrier (see, for example, Patent Documents 2 to 4).
Further, the charging state detection means is constituted by a surface potential sensor, and is configured to detect the charging state of the surface of the image carrier based on detection information of the surface potential sensor (for example, Patent Documents 1 and 4). And the charging state detecting means is composed of inflow current detecting means for detecting a current flowing through the image carrier in a state where a high voltage is applied to the charging means, and based on detection information of the inflow current detecting means. Some are configured to detect the charged state of the surface of the image carrier (see, for example, Patent Documents 2 and 3).

  In order to form a high-quality image with an electrophotographic image forming apparatus, the surface of the image carrier in the charging process is made as uniform as possible to a target charged state, specifically, a predetermined potential (for example, 800 [V]). In the conventional image forming apparatus, the charging control means sets the charging power supply means to the target charging output state so that the surface of the image carrier is in the target charging state in the charging process even in the conventional image forming apparatus. It is controlled to become.

  In the non-contact charging method described above, air discharge is positively used. However, in the charging method, when charging the surface of the image carrier with the charging unit, the charging unit and the surface of the image carrier are used. An air discharge occurs in the minute gap. For this reason, in any of the above-described charging methods, the output state of the charging power supply means necessary for setting the charged state of the surface of the image carrier to the target charged state affects the discharge conditions of the air discharge. The output state varies depending on the use environment of the image forming apparatus such as temperature, humidity, and atmospheric pressure. Therefore, in order to form a high-quality image with the image forming apparatus even if the use environment is different, it is necessary to adjust the target charge output state of the charging power supply unit in accordance with the use environment of the image forming apparatus.

  Therefore, even if the use environment when the image forming apparatus is operated changes and the discharge condition is different from the discharge condition at the time of initial setting of the target charge output state of the charging power supply means, the surface of the image carrier is subjected to the charging process. When the image forming apparatus is started up, the charge control means executes a charge adjustment process so that the charge state when the battery is charged becomes the target charge state. The control information about the target charging output state of the power supply means is adjusted.

  In view of the ease of controlling the surface potential of the image bearing member, the charging power supply means generally has a target current value that the current flowing from the charging power supply means to the charging means when a high voltage is applied to the charging means by the charging power supply means. In this case, the control information adjusted by the charging adjustment process is targeted for the target current value, and the charging power supply means is in a charged state. The current value when the charging output state is such that the target charging state (for example, the charging state where the surface potential of the image carrier is 800 [V]) is detected by the detection means (for example, the surface potential sensor). It is set as a target current value (see, for example, Patent Document 1).

  As described above, in the conventional image forming apparatus, even if the use environment is different, the charge adjustment process is executed so that the charge state obtained by the charging process becomes the same target charge state, and the detection information of the charge state detection unit is detected. The control information on the target charging output state of the charging power supply means is adjusted based on the above.

  On the other hand, as the discharge mechanism of the conventional image forming apparatus, the control information about the target discharge output state of the discharge power supply means is output from the flow-in current detection means that detects the current flowing into the image carrier due to the discharge performed by each discharger. Some discharge control means automatically adjust based on the detected information (see, for example, Patent Documents 2 and 3).

  In addition, if the control information about the target discharge output state of the power supply means for discharge is configured to be set to an appropriate value at the manufacturing factory without being automatically adjusted, the discharge condition at the time of setting When image formation is performed under different discharge conditions, the discharge amount by the discharger is different from the appropriate discharge amount. As a result, for example, when the transfer process is performed by the electrostatic transfer method, the transfer of toner to the recording paper is not performed. Inconveniences such as improper operation occur, and this affects the quality of images formed by the image forming apparatus.

  If the discharge conditions are normally changed, the effect on the image quality will be within the allowable range, but if the discharge conditions are extremely different and the discharge amount by the discharger is significantly different from the appropriate discharge amount, There is a risk that the quality of the printed image may be impaired. For example, when the device is used in a mountainous area that is higher than the altitude normally assumed as the place where the device is used, the discharge condition is improved because the atmospheric pressure in the place where the device is installed is low, and the discharge power supply means Even in the same output state, the discharge amount by the discharger is larger than the appropriate amount, and the formed image may be deteriorated depending on the altitude. In addition, if the discharge mechanism operates in an environment where the discharge conditions are extremely good, an excessive discharge current may flow through the image carrier and the photoconductor may be damaged by the overcurrent.

  In order to solve such a problem, those disclosed in Patent Documents 2 and 3 are configured such that the discharge control means automatically adjusts the control information about the target discharge output state of the discharge power supply means. Thereby, even if the discharge conditions are different, an appropriate discharge amount can be obtained for each discharger.

  In the conventional image forming apparatus, in order to set the discharge amount of each discharger to an appropriate discharge amount, the current flowing through the image carrier by the discharge of each discharger is detected. For example, in the image forming apparatus of Patent Document 2, the discharge control means sequentially generates the outputs of the discharge power supply means of a plurality of dischargers to be adjusted one by one, and the discharge of each discharger under a certain discharge condition. The control information on the target discharge output state of the discharge power supply means is automatically adjusted for each discharger by detecting the current flowing through the image carrier.

  In the image forming apparatus disclosed in Patent Document 3, the discharge control means adds a detection signal having a different frequency for each discharge power supply means to the output signal output by each discharge power supply means, and outputs the signal of this frequency. By providing a filter in the passband and extracting the inflow current by the discharger to be adjusted from the combined current flowing through the image carrier by the discharge of multiple dischargers, the discharge of each discharger under a certain discharge condition By detecting the current flowing through the image carrier, the control information on the target discharge output state of the discharge power supply means is automatically adjusted for each discharger.

JP 2001-201921 A JP-A 63-187269 JP 05-040397 A Japanese Patent Laid-Open No. 2005-274797

  However, since the above-described conventional image forming apparatus requires the above-described configuration for detecting the inflow current for each discharger, the discharge control means has the target discharge output state of the discharge power supply means. Inconvenience that it takes a long time to adjust the control information, and it takes time to start the apparatus and enter the standby state, and the configuration of the discharge control means and each discharge power supply means becomes complicated. There is room for improvement in the configuration of the discharge mechanism of the conventional image forming apparatus.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrophotographic image forming apparatus having a discharge mechanism capable of performing appropriate discharge even in a different environment with a simple configuration. In the point.

The first feature of the image forming apparatus of the present invention is that an image carrier using a photoconductor, a charge state detecting means for detecting a charge state of the surface of the image carrier, and charging in an electrophotographic image forming process. A charging mechanism for charging the image carrier in the process, and a discharge mechanism for performing air discharge in a process other than the charging process. The charging mechanism is accompanied by air discharge between the image carrier and the image carrier. A charging means for charging the surface of the image carrier, a charging power supply means for applying a high voltage to the charging means, and the charging power supply means so that the charging power supply means is in a preset target charging output state. A charge control means for controlling the output of the power supply means, and the discharge mechanism is disposed in the vicinity of the image carrier, and a plurality of dischargers for performing air discharge, and a high voltage for each of the dischargers. A plurality of discharge power supply means for applying Each of the discharge power supply means comprises a discharge control means for controlling the output of the discharge power supply means so as to be in a preset target discharge output state, and the charge control means is instructed by an image formation command. Then, a normal charging mode in which an output of the charging power supply means is controlled to charge the surface of the image carrier with the charging means, and a charging process in the normal charging mode is executed. It is configured to be switchable to an adjustment charging mode for executing charging adjustment processing for adjusting control information, and when the output of the charging power supply means is controlled by the charging processing, the surface of the image carrier is in a target charging state. As described above, in the charge adjustment processing, the electrophotographic system is configured to adjust the control information about the target charge output state based on the detection information of the charge state detection means In the image forming apparatus using,
The discharge control means controls the output of the power supply means for discharge and performs a discharge process in which discharge is performed by the discharger; and the discharge when the discharge process is executed in the normal discharge mode The target charging of the charging power supply means configured to be switchable to an adjusted discharge mode for executing a discharge adjustment process for adjusting control information of the control means and adjusted in the charge adjustment process in the discharge adjustment process. The discharge environment index is set based on the control information about the output state, and the control information about the target discharge output state of the discharge power supply means is adjusted based on the discharge environment index. is there.

According to the first feature of the present invention, the discharge environment index is set based on the control information about the target charge output state of the charging power supply means adjusted by the charge adjustment processing.
Here, in the charge adjustment process, the control information about the target charge output state is adjusted to control information about the target charge output state that can bring the surface of the image carrier into the target charge state. In the processing, charging of the image carrier by the charging means is accompanied by an air discharge that occurs under the discharge conditions at the time of executing this processing. Therefore, the control information adjusted in the charging adjustment processing is the charge adjustment. The information corresponds to the discharge condition of the air discharge in the environment in which the apparatus for performing the process is installed.

  That is, the discharge environment index is information corresponding to the discharge condition of the air discharge in the environment where the device is installed when the charge adjustment process is executed. Since the difference in discharge conditions affects the air discharge in common regardless of the charging mechanism and the discharge mechanism, the discharge environment index corresponding to the discharge condition in a certain discharge environment is the control information in the discharge mechanism. Can be used when adjusting to a value suitable for the discharge conditions.

  Therefore, an appropriate correspondence between the control information about the target charging output state and the discharge environment index and an appropriate correspondence between the control information about the target discharge output state and the discharge environment index are given to the discharge control means. If so, for example, the control information about the target charge output state and the control information about the target discharge output state are adjusted to appropriate values at the time of shipment from the factory, and the charge adjustment processing is performed at the time of starting up after installing the device. And the discharge adjustment process in the same environment, the control information about the target discharge output state of the power supply means for discharge is appropriately controlled by the discharge mechanism under the discharge condition at the place where the apparatus is installed. The control information can be discharged.

  As described above, according to the first feature of the present invention, the control information about the target discharge output state is automatically set to an appropriate one suitable for the discharge condition by a simple configuration in which the discharge control means executes the discharge adjustment process. Thus, an electrophotographic image forming apparatus provided with a discharge mechanism capable of appropriate discharge even in a different environment has been obtained with a simple configuration.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control information about the target charging output state of the charging power supply means adjusted by the charging control means is a current output from the charging power supply means. Is the target current value.

According to the 2nd characteristic of this invention, in addition to the effect | action similar to the 1st characteristic of this invention, there exist the following effects.
When the charge control means executes the charge adjustment process in the adjustment charge mode, the target current value of the charging power supply means is charged so that the current on the surface of the image carrier becomes the target charged state under the discharge conditions at that time. It adjusts so that it may be output from the power supply means. Necessary when the charge state on the surface of the image carrier is set to the target charge state under certain discharge conditions because the amount of discharge generated varies depending on the discharge conditions even if the output of the charging power supply means is the same output. The current output from the charging power supply means varies depending on the discharge conditions.

  Therefore, the discharge condition is indicated by the discharge environment index that is set based on the target current value that has been adjusted by the charge adjustment process, and the discharge power supply means that is adjusted based on such a discharge environment index. The control information on the target discharge output state can perform appropriate discharge under the discharge condition indicated by the discharge environment index, and thus a suitable means for implementing claim 1 can be obtained.

  A third feature of the present invention is that, in the first or second feature of the present invention, the charged state detection means is constituted by a surface potential sensor for detecting a surface potential of the image carrier.

According to the 3rd characteristic of this invention, in addition to the effect | action similar to the 1st or 2nd characteristic of this invention, there exist the following effects.
In order to detect the surface potential of the image carrier by the surface potential sensor, for example, unlike the case of detecting the charged state of the surface of the image carrier indirectly based on the current value flowing into the image carrier from the charging means, the image Since the charge state of the surface of the carrier can be directly detected, the charge control means can be controlled so that the charging power source means is in the target charge output state based on the detection information of the surface potential sensor. The charged state of the surface can be accurately set to the target charged state, so that a suitable means for carrying out the first or second aspect can be obtained.

  According to a fourth feature of the present invention, in any one of the first to third features of the present invention, the control information about the target discharge output state of the power supply means for discharge adjusted by the discharge control means is electronic. This is the target current value of the current output from the power supply means for transfer discharge that applies a high voltage to the transfer discharger used for discharge in the transfer process in the photographic system.

According to the 4th characteristic of this invention, in addition to the effect | action similar to any one of the 1st-3rd characteristic of this invention, there exist the following effects.
The target current value of the current output by the transfer discharge power supply means for applying a high voltage to the transfer discharger used for the discharge in the transfer process is the discharge condition when the charge adjustment processing is executed by the charging power supply means. Therefore, it is possible to obtain a desired discharge state in the transfer process even if the installation environment of the apparatus is different. A suitable means for carrying out is obtained.

  Hereinafter, an embodiment of an image forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an image forming unit of a monochromatic laser printer to which the present invention is applied.

  In FIG. 1, reference numeral 1 denotes a photosensitive drum as an image bearing member formed by coating an organic photosensitive member on the surface of an aluminum drum base, and 2 denotes a surface of the photosensitive drum 1 by corona discharge in a charging process. Charging scorotron as a charging means for charging a positive charge, 3 is a charging power supply as a charging power supply means for applying a high voltage to the charging scorotron 2, and 4 is a charging control means for controlling the output of the charging power supply 3. It is a control device. The charging mechanism T is constituted by the charging scorotron 2, the charging power source 3, and the charging control device 4.

  In FIG. 1, reference numeral 5 denotes a surface of the photosensitive drum 1 by removing the electric charge on the surface of the photosensitive drum 1 by scanning the surface of the photosensitive drum 1 with a rotating mirror using laser light emitted from a switchable semiconductor laser. An exposure unit 6 for forming an electrostatic latent image with a well-type potential is a surface as a charged state detecting means for detecting the charged state of the surface of the photosensitive drum 1 by detecting the potential of the surface of the photosensitive drum 1. The potential sensor 7 is a developing device that electrostatically attaches positively charged toner to the electrostatic latent image formed on the surface of the photosensitive drum 1 by a reversal development method.

  In FIG. 1, reference numeral 8 denotes a pre-transfer scorotron that charges the toner attached to the photosensitive drum 1 with a positive charge by corona discharge, 9 denotes a pre-transfer power source that applies a high voltage to the pre-transfer scorotron 8, and 10 denotes the photosensitive drum 1. A toner image formed on the surface of the photosensitive drum 1 by applying corona discharge to the toner image from the back side of the recording paper P at the position where the recording paper P overlaps with the opposite polarity to the toner charge, that is, negative charge. Is a transfer corotron that moves and adheres to the recording paper P by electrostatic force, 11 is a transfer power source that applies a high voltage to the transfer corotron 10, and 12 is a static discharge of the recording paper P electrostatically attracted to the photosensitive drum 1 by corona discharge. A separation corotron 13 that performs corona discharge in a separation process of a static elimination separation system that reduces electrostatic attraction force and separates the recording paper P by utilizing the rigidity and its own weight. Separating power supply for applying a high voltage to the release corotron 12, 14 is a discharge control device for a discharge control means for controlling the pre-transfer power source 9, the output of the transfer power supply 11 and a separated power 13 to each other.

  As described above, the printer includes the pre-transfer scorotron 8, the transfer corotron 10 and the separation corotron 12 as a plurality of dischargers, and the pre-transfer power source 9, the transfer power source 11 and the separation power source 13 as a plurality of discharge power supply means. A discharge control device 14 is provided as a discharge control means for controlling the output of these discharge power supply means, and a discharge mechanism H is constituted by the plurality of dischargers, the plurality of discharge power supply means and the discharge control means. is doing.

  In FIG. 1, reference numeral 15 denotes a static eliminator that removes the charge on the surface of the photosensitive drum 1 that has been charged by exposing the photosensitive member on the surface of the photosensitive drum 1, and 16 mechanically removes toner remaining on the surface of the photosensitive drum 1. The brush cleaner 17 includes a fixing roller 17a including a heater for heating, and a pressure roller 17b provided in a state where the fixing roller 17a is joined in parallel with the fixing roller 17a, and the recording paper conveyed by both rollers. When P passes through the joint between both rollers, the toner on the recording paper P is thermally melted and pressed to fix the powdery toner transferred to the recording paper P in the transfer process onto the recording paper P. It is a fixing device.

  With the configuration outlined above, this printer can perform various processes such as charging, exposure, development, pre-transfer, transfer, separation, fixing, static elimination, and cleaning based on image formation commands and image information from a host device (for example, a personal computer). After that, image formation is performed.

  The charging control means 4 performs constant current control using the output current value Ic of the charging power supply 3 as a control parameter in the charging process, and outputs the constant current to the charging scorotron 2. Is configured to perform feedback control.

  The charging control means 4 is communicably connected to the discharge control device 14 and the main control device MC, and can be switched between the normal charging mode MTn and the adjustment charging mode MTc in accordance with a command from the main control device MC. It is configured.

  In the normal charging mode MTn, when an image formation command is instructed from the main controller MC, a charging process is performed for feedback control so that the current value Ic output from the charging power supply 3 becomes a preset target charging current value Icc. Executed. In the adjustment charging mode MTc, a charge adjustment process is executed in which the target charging current value Icc is adjusted according to the discharge conditions based on the environment (atmospheric pressure, temperature, humidity, etc.) of the printer installation location.

In the charge adjustment process, the surface potential Vs of the surface of the photosensitive drum 1 is set by the discharge of the charging scorotron 2 when the constant current control is performed based on the target charging current value Icc under the discharge condition when this process is executed. Based on the detection information of the surface potential sensor 5, the target charging current value Icc of the charging power supply means 3 is adjusted so as to be a potential (for example, 800 [V]).
Since the initial value of the target charging current value Icc is set based on the detection information of the surface potential sensor 5 in the adjustment process at the production factory, the discharge conditions in the production site environment (atmospheric pressure, temperature, humidity, etc.) The surface potential Vs of the photosensitive drum 1 is set to the target potential (for example, 800 [V]) by the corona discharge by the charging scorotron 1, and becomes a target charging current value Icc.

  As described above, the charging control device 4 of the printer controls the output of the charging power source 3 and charges the surface of the photosensitive drum 1 by the charging scorotron 2 when an image formation command is issued from the main control device MC. It is configured to be switchable between a normal charging mode MTn for executing the charging process and an adjustment charging mode MTc for executing a charge adjusting process for adjusting the target charging current value Icc when executing the charging process in the normal charging mode MTn. In the charging adjustment process, the target charging current value Icc is set to the surface potential so that the surface of the photosensitive drum 1 becomes the target potential when the output of the charging power source 3 is controlled at a constant current based on the target charging current value Icc. It is configured to adjust based on detection information of the sensor 6.

  The charging control means 4 also controls the grid bias voltage output from the charging power source 3 in the normal charging mode MTn and the adjustment charging mode MTc, and is a constant value (for example, 800 [V]) with respect to the grid electrode 2g. ) Is applied.

  In the pre-transfer, transfer, and separation processes, which are other processes that perform corona discharge in processes other than the charging process, the discharge control device 14 corresponds to each power source (pre-transfer power source 9, transfer power source 11, and separation power source 13). ) Output.

  For the pre-transfer power supply 9, the discharge control device 14 performs constant voltage control using the pre-transfer voltage value V 1, which is the output voltage value, as a control parameter to feedback control the output of the pre-transfer power supply 9. Performs a constant current control using the transfer current value I2 that is the output current value as a control parameter to feedback control the output of the transfer power supply 11, and for the separation power supply 13, the separation voltage value V3 that is the output voltage value is used. It is configured to perform constant voltage control as a control parameter and feedback control the output of the separated power supply 13.

  The discharge control device 14 is communicably connected to the charging control device 4 and the main control device MC, and can be switched between a normal discharge mode MHn and an adjusted discharge mode MHc in accordance with a command from the main control device MC. It is configured.

  In the normal discharge mode MHn, when an image formation command is commanded from the main controller MC, in the pre-transfer process, the pre-transfer power source 9 is set so that the pre-transfer voltage value V1 of the pre-transfer power source 9 becomes the target pre-transfer voltage value V1m. The output of the transfer power supply 11 is controlled at a constant current so that the transfer current value I2 of the transfer power supply 11 becomes the target transfer current value I2m in the transfer process, and the separation power supply 13 is separated in the separation process. A discharge process is performed in which the output of the separation power supply 13 is controlled at a constant voltage so that the voltage value V3 becomes the target separation voltage value V3m.

  In the adjusted discharge mode MHc, the target value of the control parameter, which is control information, is adjusted for the target discharge output state of each power source of the discharge mechanism H so as to meet the discharge conditions based on the usage environment of the apparatus. Specifically, the discharge environment index EnvLv for evaluating the discharge condition is set based on the target charging current value Icc after being adjusted by the charge adjustment processing that is the control information of the charge control means, and the target pre- A discharge adjustment process for adjusting the values of the transfer voltage value V1m, the target transfer current value I2m, and the target separation voltage value V3m based on the value of the discharge environment index EnvLv is executed.

  The charge adjustment process executed by the charge control device 4, the discharge adjustment process executed by the discharge control device 14, and the control operation of the main control device MC will be described based on the flowcharts shown in FIGS.

As shown in FIG. 2, when the apparatus is activated, main controller MC waits for a charge adjustment completion signal transmitted by charge control apparatus 4 (to be described later) after execution of charge adjustment processing (#step 1). When a charge adjustment completion signal is received from the charge control means, a charge mode switching command is output to the charge control device 4 (step # 2). Then, it will be in a standby state until the discharge adjustment process which the discharge control means 14 performs is completed (step # 3). When a discharge adjustment completion signal is received from the discharge control means 14, it enters a standby state for image formation information from the outside such as a personal computer (step # 4). When the image formation information is received, the image formation command is output to the charge control device 4 and the discharge control device 14 (step # 5).
Although not shown in the flowchart of FIG. 2, the main controller MC also manages control of device operations related to other processes such as the exposure unit 5 and the development unit 7.

  As shown in FIG. 3, the charging control device 4 executes a charge adjustment process when the device is started (step # 1). When the execution of the charge adjustment processing is completed, a charge adjustment completion signal is output to the main control device MC and the discharge control device 14 (step # 2), and a standby state for receiving a charge mode switching command from the main control device MC. (Step # 3). When the charging mode switching command is detected, the charging mode is switched from the adjustment charging mode MTc to the normal charging mode MTn (step # 4), and the image forming command from the main controller MC is waited (step # 5). In the normal charging mode MTn, charging processing is executed every time an image formation command is received (step # 5 to step # 6). In the charging process of step # 6, as described above, the output of the charging power supply 4 is feedback-controlled so that the output current value Ic of the charging power supply 3 becomes the target charging current value Icc.

  As shown in FIG. 4, when the apparatus is activated, the discharge control device 14 waits for a charge adjustment completion signal transmitted by the charge control device 4 after the execution of the charge adjustment processing (#step 1). When a charge adjustment completion signal is received from the charge control means, a discharge adjustment process described later is executed (step # 2). When the execution of the discharge adjustment process is completed, a discharge adjustment completion signal is output to main controller MC (step # 3), and a standby state for receiving a discharge mode switching command from main controller MC is entered (step #). 4). When the discharge mode switching command is detected, the charging mode is switched from the adjusted discharge mode MHc to the normal discharge mode MHn (step # 5), and the image formation command from the main controller MC is waited (step # 6). In the normal discharge mode MHn, discharge processing is executed every time an image formation command is received (step # 6 to step # 7). In the discharge process of step # 7, as described above, the output of each discharge power supply is feedback-controlled so that the control parameter of each discharge power supply becomes the target value.

  The charge adjustment processing executed by the charge control device 4 in step # 1 of FIG. 3 will be described based on the flowchart shown in FIG. In the charging adjustment process, first, the current value Ic output from the charging power source 3 is set to the target charging current value Icc (hereinafter referred to as the initial target charging current value) initially set at the time of factory production and stored in the storage unit of the charging control device 4. The output of the charging power source 3 is controlled so as to be Icc_ini (step # 1). At this time, the surface potential Vs of the photosensitive drum 1 is detected by the surface potential sensor 6, and based on the detection information, is the surface potential Vs of the photosensitive drum 1 higher than a target potential (for example, 800 [V]) (step)? # 2) It is checked whether it is low (step # 3). If the surface potential Vs is higher than the target potential, the discharge amount is excessive and the target charging current value Icc is set to a value smaller by 5 [μA] (step # 4). Conversely, the surface potential Vs is set to the target potential. If it is lower, the discharge amount is too small and the target charging current value Icc is set to a value larger by 5 [μA] (step # 5).

  By repeating the processes of Step # 1 to Step # 5, the target charging current value Icc is set so that the surface potential Vs of the photosensitive drum 1 becomes the target potential. The charging control device 4 stores the target charging current value Icc adjusted by the charging adjustment process in the storage unit separately from the initial target charging current value Icc_ini.

  As described above, when the charge control device 4 executes the charge adjustment process, the surface potential Vs of the photosensitive drum 1 is charged to the target potential by the corona discharge generated by the high voltage applied to the charging scorotron 2 by the charging power source 3. In addition, the target charging current value Icc is adjusted according to the discharge conditions based on the environment (atmospheric pressure, temperature, humidity, etc.) of the printer installation location.

  The discharge adjustment process performed by the discharge control device 14 in step # 2 of FIG. 4 will be described based on the flowchart shown in FIG. In the discharge adjustment process, the initial target charging current value Icc_ini and the target charging current value Icc adjusted in the charging adjustment process are acquired from the charge control device 4 (step # 1). A discharge environment index table TBL as shown in FIG. 7 is stored in the storage unit of the discharge control device 14, and each of the initial target charging current value Icc_ini and the target charging current value Icc adjusted by the charging adjustment processing is stored. Is obtained with reference to the discharge environment index table TBL (step # 2).

  In the discharge environment index table TBL, values D1 to D6 obtained experimentally as values for relatively evaluating the discharge conditions are set for each category of the target charging current value Icc. Since the target charging current value Icc is a value adjusted by the charging adjustment processing corresponding to the discharge condition so that the surface of the photosensitive drum 1 can be appropriately charged even if the discharge condition changes, the target charging current value It is possible to set the relative evaluation value of the discharge condition in a form corresponding to Icc.

  In step # 3, the discharge environment ratio R of the two acquired discharge environment indices EnvLv is calculated. For example, since the initial target charging current value Icc_ini at the time of device production is 400 [μA] and the discharge condition is good, for example, the altitude is 2000 [m], the target adjusted by the charge adjustment processing is installed. When the charging current value Icc is 320 [μA], the discharge environment ratio R is R = D2 / D6 according to FIG.

  When the discharge environment ratio R is calculated, the target value of the control parameter of each high-voltage power supply device controlled by the discharge control device 14 in each of the pre-transfer process, the transfer process, and the separation process is adjusted. Specifically, in step # 4, the target pre-transfer voltage value V1m of the voltage output from the pre-transfer power source 9 to the pre-transfer scorotron 8 in the pre-transfer process is corrected as V1m = V1m × (1 / R). . In step # 5, the target transfer current value I2m of the current output from the transfer power supply 11 to the transfer corotron 10 in the transfer process is corrected as I2m = I2m × (1 / R). In step # 6, the target separation voltage value V3m of the voltage output from the separation power source 13 to the separation corotron 12 in the separation process is corrected as V3m = V3m × (1 / R).

  For example, when the target transfer current value I2m in the transfer process is set to 120 [μA] as an appropriate value at the time of device production, the initial target charging current value when the discharge environment ratio R = 1.25 as in the above-described example Assuming this printer is set under an environment with a discharge condition that is easier to discharge by 1.25 times than the discharge condition at the time of device production with Icc_ini set, the target transfer current value I2m is I2m = 120 × (1 / 1.25) is set to I2m = 96 [μA].

  In the separation process, a voltage obtained by superimposing the AC component on the DC component is applied. For example, the DC component voltage of the target separation voltage value V3m is 1300 [V] as an appropriate value during the production of the device, and the AC component peak. When the inter-voltage is set to 5.0 [Rms] as an appropriate value during device production, the appropriate value set during device production is maintained for the DC component, and the AC component is 5.0 x (1 / 1.25) and V3m = 4.0 Set to [Rms]. As for the target pre-transfer voltage value V1m, the peak-to-peak voltage for AC is set in the same manner as the target separation voltage value V3m.

  As described above, when the discharge control device 14 executes the discharge adjustment process, the target pre-transfer voltage value V1m and the target transfer current value I2m are matched to the discharge conditions based on the environment (atmospheric pressure, temperature, humidity, etc.) of the printer installation location. And the target separation voltage value V3m is set to an appropriate value.

  As described above, in the printer, the control information (specifically, the target charging current Icc) automatically adjusted by the charge adjustment process executed when the charge control device 4 is started up at the place where the device is used is set to values before and after adjustment. The discharge environment index EnvLv for evaluating the discharge condition in each environment is set, and the difference between the discharge condition in the production environment of the apparatus and the discharge condition in the use environment of the apparatus is grasped as a discharge environment ratio R. Transfer process and separation so that a discharge amount equivalent to the discharge amount based on the target value of the control parameter set to an appropriate value under the discharge conditions in the device can be obtained under the discharge conditions in the operating environment of the equipment. The target value of the control parameter for the discharge of the discharger in a process other than the charging process such as the process is adjusted.

  In other words, the printer has a simple configuration that does not require a configuration for specifically detecting the discharge amount of each discharger 8, 10, 12 of the discharge mechanism H, and each of the plurality of dischargers 8, 10, 12 has a simple configuration. The target pre-transfer voltage value V1m, the target transfer current value I2m, and the target separation voltage value V3m, which are control information, can be collectively adjusted to appropriate values according to the discharge conditions.

[Another embodiment]
Hereinafter, other embodiments are listed.
(1) In the above embodiment, the image carrier is constituted by the drum-type photosensitive drum 1, but the image carrier is constituted in other forms such as a belt-like one. There may be.
(2) In the above embodiment, the charging state detection unit is exemplified by the surface potential sensor 6, but instead, the charging state detection unit detects a current flowing from the charging unit to the image carrier. There may be provided a current detecting means for detecting the charged state of the surface of the image carrier based on the detection information of the current detecting means.
(3) In the above embodiment, the charging unit is exemplified by the charging scorotron 2. However, the charging unit may be configured by a charging roller, a charging brush, or the like.
(4) In the above embodiment, the charge control device 4 serving as the charge control means and the discharge control device 14 serving as the discharge control means are illustrated as separate devices from the main control device MC. It may be configured integrally with the MC or separately.
(5) In the above embodiment, the charging control means has exemplified the mode in which the target charging current value Icc is changed by 5 [μA] in the charging adjustment process, but the mode of change of the target charging current value Icc is exemplified. It is not limited to the above, and may be changed continuously.
(6) In the above embodiment, the discharge control means has the target pre-transfer voltage value V1m, the target transfer current value I2m, the target information that is control information about the target charging output state of the pre-transfer power source 9, the transfer power source 11, and the separation power source 13. The separation voltage value V3m is illustrated as being configured to be adjusted by the discharge adjustment process. However, the discharge adjustment is performed for only one power source or for control information about the target charge output state of any one of a plurality of power sources. It may be configured to adjust by processing.
(7) In the above embodiment, the discharge control means has exemplified the configuration in which the discharge environment index EnvLv corresponding to the charging target current value Icc is obtained by referring to the discharge environment index table TBL in the discharge adjustment processing. The configuration may be such that the discharge environment index EnvLv corresponding to the charging target current value Icc is obtained by calculating based on the target current value Icc by a mathematical expression.
(8) The present invention is also applicable to an image forming apparatus that forms a full-color image.

Configuration block diagram of main parts of image forming apparatus Flow chart showing control operation of main controller Flow chart showing control operation of charging controller Flow chart showing control operation of discharge control device Flow chart showing processing contents of charging adjustment processing Flow chart showing processing contents of discharge adjustment processing Figure showing the discharge environment index table

Explanation of symbols

T Charging mechanism H Discharging mechanism MTc Adjusted charging mode MTn Normal charging mode MHc Adjusted discharge mode MHn Normal discharging mode Vs Detection information of charging state detection means (surface potential sensor)
Control information on Icc target charging output status (target current value of current output by charging power supply means)
V1m, I2m, V3m Control information about target discharge output status
EnvLv, D1 to D6 Discharge environment index 1 Image carrier 2 Charging means 3 Charging power supply means 4 Charging control means 6 Charged state detecting means (surface potential sensor)
8, 10, 12 Discharger 9, 11, 13 Discharge power supply means 14 Discharge control means

Claims (4)

An image carrier using a photoreceptor;
Charged state detection means for detecting the charged state of the surface of the image carrier;
A charging mechanism for charging the image carrier in a charging process in an image forming process by an electrophotographic method, and a discharging mechanism for performing air discharge in a process other than the charging process;
The charging mechanism is
Charging means for charging the surface of the image carrier with air discharge between the image carrier and the image carrier;
Charging power supply means for applying a high voltage to the charging means;
Charging control means for controlling the output of the charging power supply means so that the charging power supply means is in a preset target charging output state,
The discharge mechanism is
A plurality of dischargers disposed in the vicinity of the image carrier and performing air discharge;
A plurality of discharge power supply means for applying a high voltage to each of the dischargers;
A discharge control means for controlling the output of the discharge power supply means so that each of the discharge power supply means is in a preset target discharge output state;
The charging control means;
When an image formation command is issued, a normal charging mode for controlling the output of the charging power supply means and charging the surface of the image carrier with the charging means, and the charging in the normal charging mode. It is configured to be switchable to an adjustment charge mode for executing charge adjustment processing for adjusting control information when executing processing,
In the charging adjustment process, control information about the target charging output state is provided in the charging state so that the surface of the image carrier is in the target charging state when the output of the charging power supply means is controlled in the charging process. An image forming apparatus using an electrophotographic system configured to adjust based on detection information of a detection means,
The discharge control means
The control information of the discharge control means when executing the discharge process in the normal discharge mode, and the normal discharge mode for executing the discharge process for controlling the output of the power supply means for discharging and discharging with the discharger Control information about the target charge output state of the charging power supply means configured to be switchable to an adjusted discharge mode for executing a discharge adjustment process to be adjusted, and adjusted in the charge adjustment process in the discharge adjustment process An image forming apparatus configured to set a discharge environment index based on the control information and adjust control information about the target discharge output state of the power supply means for discharge based on the discharge environment index.   2. The image forming apparatus according to claim 1, wherein the control information about the target charging output state of the charging power supply means adjusted by the charging control means is a target current value of a current output from the charging power supply means.   The image forming apparatus according to claim 1, wherein the charged state detection unit is configured by a surface potential sensor that detects a surface potential of the image carrier.   A transfer discharge power supply in which control information about the target discharge output state of the discharge power supply means adjusted by the discharge control means applies a high voltage to a transfer discharger used for discharge in a transfer process in electrophotography. The image forming apparatus according to claim 1, wherein the image forming apparatus is a target current value of a current output by the means.

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