JP2017167184A - Image forming apparatus and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve control according to air pressure while suppressing an increase in cost in an image forming apparatus.SOLUTION: A process control part of an MFP predicts the air pressure at a place where the MFP is installed and changes the design aspect of an image forming process in the MFP according to the predicted air pressure. The process control part acquires, for example, (1) the film thickness of a charging roller 42, (2) the temperature of the place where the MFP 100 has been installed, and (3) the humidity of the place where the MFP 100 has been installed, and acquires values associated with these values on a table to acquire the predicted value of the air pressure.SELECTED DRAWING: Figure 4

Description

  The present disclosure relates to an image forming apparatus that forms an image by an electrophotographic method, and a control method for such an image forming apparatus.

  Conventionally, there has been an image forming apparatus such as an MFP (Multi-Functional Peripheral) that forms an image by an electrophotographic method. In such an image forming apparatus, an image forming process (hereinafter also simply referred to as “process”) using a phenomenon of discharge is used for charging, developing, and transferring. The discharge mode can be changed according to the atmospheric pressure. The design of the image forming process normally assumes the use of the image forming apparatus in an environment of 1 atm.

  When the image forming apparatus is used in a place where the atmospheric pressure is low (for example, high altitude), the process design is changed according to the atmospheric pressure. More specifically, for example, a service person inputs the atmospheric pressure. The image forming apparatus redesigns the process according to the input atmospheric pressure.

  If the service person makes an incorrect entry of barometric pressure, the process design may also be wrong. Japanese Patent Application Laid-Open No. 06-130770 (Patent Document 1) discloses an image forming apparatus including an element dedicated to atmospheric pressure detection in order to more appropriately design a process design.

Japanese Patent Laid-Open No. 06-130770

  However, according to the technique disclosed in Patent Document 1, the cost for the element for detecting the atmospheric pressure is added in the manufacture of the image forming apparatus.

  The present disclosure has been devised in view of such circumstances, and an object thereof is to realize control according to atmospheric pressure while suppressing an increase in cost in an image forming apparatus.

  According to an aspect of the present disclosure, an image forming apparatus provided by the present disclosure is configured to acquire a temperature and humidity, and a first acquisition unit configured to acquire the film thickness of the photoreceptor. Based on the second acquisition unit, the film thickness of the photoreceptor acquired by the first acquisition unit, and the temperature and humidity acquired by the second acquisition unit, the location of the image forming apparatus is installed. And a controller configured to specify an estimated value of the atmospheric pressure. The control unit is configured to control an image forming process in the image forming apparatus based on the estimated value.

  Preferably, the image forming apparatus further includes a charging roller for charging the photoconductor. The control unit is further configured to identify an estimated value of the atmospheric pressure at the location where the image forming apparatus is installed based on a ratio of a change in the current flowing through the charging roller with respect to a change in the voltage applied to the charging roller. Has been.

  According to another aspect of the present disclosure, an image forming apparatus provided by the present disclosure flows to a charging roller with respect to a change in a voltage applied to the photosensitive member, a charging roller for charging the photosensitive member, and the charging roller. And a control unit configured to identify an estimated value of the atmospheric pressure of the place where the image forming apparatus is installed based on the rate of change in current. The control unit is configured to control an image forming process in the image forming apparatus based on the estimated value.

  Preferably, the image forming apparatus further includes a voltage supply unit configured to supply the charging roller with a voltage obtained by superimposing an AC voltage on a DC voltage. The voltage applied to the charging roller is higher than the voltage at which discharge starts in the photoreceptor charged by the charging roller.

  Preferably, the control unit is configured to control the image forming process based on the estimated value when the photosensitive member is used for the first time.

  Preferably, the control unit is configured to control the image forming process based on the estimated value when energization of the substrate on which the control unit is mounted is started.

  Preferably, the control unit is configured to control the image forming process based on the estimated value when energization of the control unit is started.

  Preferably, the control unit is configured to control the image forming process based on the estimated value when it is detected that a certain period has elapsed since the previous image formation in the image forming apparatus.

  Preferably, the control of the image forming process includes control of at least one of a charging voltage, a developing voltage, and a transfer voltage.

  According to still another aspect of the present disclosure, a method for controlling an image forming apparatus includes: obtaining a film thickness of a photoconductor, and a temperature and humidity of a place where the image forming apparatus is installed; and a film thickness of the photoconductor , Based on the temperature and humidity, specifying an estimated value of the atmospheric pressure of the place where the image forming apparatus is installed, and controlling an image forming process in the image forming apparatus based on the estimated value.

  According to still another aspect of the present disclosure, a control method of an image forming apparatus is based on a ratio of a change in a current flowing through a charging roller to a change in a voltage applied to a charging roller for charging a photoconductor. Specifying an estimated value of the atmospheric pressure at the place where the forming apparatus is installed, and controlling an image forming process in the image forming apparatus based on the estimated value.

  According to the present disclosure, the image forming apparatus can control the image forming process according to the atmospheric pressure without including a dedicated element for detecting the atmospheric pressure.

1 is a diagram illustrating a specific example of the appearance of an embodiment of an image forming apparatus. 2 is a diagram illustrating a specific example of a hardware configuration of an MFP. FIG. FIG. 3 is a diagram for explaining a detailed configuration of the printer of FIG. 2. 3 is a diagram schematically illustrating an example of a table used for MFP control. FIG. FIG. 6 is a diagram schematically illustrating an example of correspondence between set values of a charging voltage, a developing voltage, and a transfer voltage and an atmospheric pressure at a place where an MFP is installed. It is a figure for demonstrating an example of the setting aspect of a reference value. FIG. 6 is a diagram for explaining changes in the behavior of current and voltage of a charging roller when the atmospheric pressure at a place where an MFP is installed changes. 6 is a flowchart of processing executed to realize process design according to the atmospheric pressure of a place where an MFP is installed.

  Hereinafter, embodiments of an information processing apparatus will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, these descriptions will not be repeated.

<1. Appearance of image forming apparatus>
FIG. 1 is a diagram illustrating a specific example of the appearance of an embodiment of an image forming apparatus. As shown in FIG. 1, MFP 100 as an example of an image forming apparatus includes an operation panel 15. The image forming apparatus may be, for example, a printer, a facsimile transceiver, or a copier. The MFP 100 is an image forming apparatus having a combination of these functions.

<2. Hardware configuration>
FIG. 2 is a diagram illustrating a specific example of the hardware configuration of the MFP 100. As shown in FIG. 2, the MFP 100 includes a CPU (Central Processing Unit) 10 that is an arithmetic device for controlling the whole.

  The MFP 100 further includes a ROM (Read Only Memory) 11 for storing a program executed by the CPU 10, a RAM (Random Access Memory) 12 for functioning as a work area when the CPU 10 executes the program, not shown. A scanner 13 for optically reading a document placed on a document table to obtain image data, a printer 14 for fixing the image data on a printing paper, and displaying information or operating input to the MFP 100 An operation panel 15 including a touch panel for receiving, an HD (hard disk) 16 for storing image data and the like, and a network controller 17 for controlling communication via a network are included.

  The program executed by the CPU 10 may be stored in a storage device on the network in addition to being stored in the ROM 11, or may be downloaded from the network and installed in the HD 16, Further, it may be stored in a recording medium that is detachable from MFP 100.

<3. Detailed printer configuration>
FIG. 3 is a diagram for explaining a detailed configuration of the printer 14 in FIG. 2.

  The printer 14 includes an image forming unit 40 and a printer control unit 50 for controlling the image forming unit 40. The image forming unit 40 includes a photoconductor 41, a charging roller 42, a current detection unit 43, and a charging voltage supply unit 44.

  In the image forming unit 40, the charging roller 42 contacts the photoconductor 41 and is applied with a voltage required for image formation from the charging voltage supply unit 44. For example, the charging voltage supply unit 44 supplies the charging roller 42 with a voltage obtained by superimposing an alternating current (AC) voltage on a direct current (DC) voltage. When a voltage is applied from the charging voltage supply unit 44 to the charging roller 42, a potential difference is generated between the surface of the charging roller 42 and the photoreceptor 41.

  When the potential difference between the surface of the charging roller 42 and the photoconductor 41 becomes equal to or greater than a predetermined potential difference determined by Paschen's law, a discharge occurs, whereby the photoconductor 41 is charged. A current flows due to the movement of charges between the charging roller 42 and the charged photoconductor 41. The current detection unit 43 detects the value of the current flowing between the charging roller 42 and the photoconductor 41.

  In the image forming unit 40, the value of the current flowing between the charging roller 42 and the photoconductor 41 when a voltage having a predetermined value is applied to the charging roller 42 is the environment (for example, temperature, (Humidity, atmospheric pressure) and the film thickness of the photoconductor 41 may vary. From this, based on the current value and the voltage value, the temperature and humidity of the place where the MFP 100 is installed, and the film thickness of the photoreceptor 41, the atmospheric pressure of the place where the MFP 100 is installed is obtained.

  The printer control unit 50 includes a process control unit 51, a film thickness detection unit 52, a temperature / humidity detection unit 53, a development voltage control unit 54, and a transfer voltage control unit 55. The process control unit 51 includes a CPU 511 and a memory 512 for storing programs executed by the CPU 511 and various data. An example of data stored in the memory 512 is a table for specifying a predicted value of atmospheric pressure where the MFP 100 is installed. FIG. 4 is a diagram schematically illustrating an example of the table. However, the table shown in FIG. 4 need not be stored in the storage device in MFP 100 as long as it is stored in a storage device accessible by CPU 511.

In the table shown in FIG. 4, for example, the following four types of values are associated with each other.
(1) Film thickness of the charging roller 42 (2) Temperature at the place where the MFP 100 is installed (3) Humidity at the place where the MFP 100 is installed (4) Air pressure at the place where the MFP 100 is installed Returning to FIG. The unit 51 controls various operations of the image forming unit 40. For example, the process control unit 51 predicts the air pressure at the place where the MFP 100 is installed, and changes the design mode of the image forming process in the image forming unit 40 or the like according to the predicted air pressure.

  The prediction of the atmospheric pressure is performed by, for example, acquiring the three types of values (1) to (3) mentioned above with reference to the table in FIG. 4 and the atmospheric pressure associated with the acquired three types of values. Obtaining from a table. The pressure value acquired in this way is an example of the predicted value of the pressure.

  An example of a process design change mode will be described. When the atmospheric pressure of the environment in which the image forming apparatus is installed decreases, the discharge current from the discharger increases. Furthermore, depending on the change in the behavior of the peeling discharge that occurs when the object in contact with the dielectric is peeled off, the photosensitive member (photosensitive drum), the intermediate transfer member, the transfer member conveying member (for example, the transfer drum), or these The toner and / or transfer material (for example, transfer paper) on the surface becomes excessively charged and discharged, which may cause image defects, transfer defects, transfer material peeling defects, and cleaning defects. In order to reliably avoid the occurrence of such a problem, the process control unit 51 determines the voltage (hereinafter referred to as “charging voltage”) applied to the charging roller 42 by the charging voltage supply unit 44 according to the predicted value of atmospheric pressure. In addition, an output value related to development and transfer (not shown) in the MFP 100 is adjusted. A method for adjusting the output value relating to charging, development, and transfer will be described later.

  The film thickness detector 52 acquires the film thickness of the photoconductor 41. For example, the film thickness detection unit 52 acquires the film thickness of the photoconductor 41 based on information input to the operation panel 15. In another example, the film thickness detection unit 52 acquires the film thickness of the photoconductor 41 based on the physical quantity detected by the MFP 100. The film thickness detector 52 may be realized by a film thickness measurement sensor. The film thickness measurement sensor may be an eddy current type sensor or an optical interference type sensor (for example, one sold by Fisherscope or Keyence).

  The film thickness detector 52 may acquire the film thickness of the photoconductor 41 based on an estimated value calculated based on the number of printed sheets in the MFP 100 and the rotation speed of the photoconductor 41. The estimated value (film thickness T) is calculated according to the following formula (1) or formula (2), for example.

Film thickness T = initial film thickness TS-1 wear amount WP × number of printed sheets NP per sheet printing (1)
Film thickness T = Initial film thickness TS-1 Amount of wear WR × rotational speed NR per rotation (2)
The “initial film thickness TS” is the initial film thickness of the photoconductor 41. “Amount of wear WP per sheet print” is the amount of wear of the photoconductor 41 when the MFP 100 prints one sheet of paper. “Number of printed sheets NP” is the number of sheets printed by MFP 100. The “amount of wear WR per rotation” is the amount of wear of the photoconductor 41 per rotation of the photoconductor 41. “Rotation speed NR” is the number of times the photoconductor 41 has rotated. The memory 512 stores data specifying “amount of wear WP per sheet printing” and / or “amount of wear WR per rotation”. In MFP 100, “number of printed sheets NP” and / or “number of rotations NR” is counted for photoconductor 41 and stored in memory 512. The memory 512 stores “initial film thickness TS”. The process control unit 51 reads an appropriate value in the memory 512 and calculates the film thickness T according to the formula (1) or the formula (2).

  Temperature / humidity detection unit 53 acquires the temperature and humidity of the place where MFP 100 is installed. In one example, the temperature / humidity detection unit 53 acquires the temperature and / or humidity of the place based on information (for example, numerical values of temperature and humidity) input to the operation panel 15. In another example, the temperature / humidity detection unit 53 acquires the temperature and / or humidity of the place based on the physical quantity detected by the MFP 100.

  The development voltage controller 54 controls a voltage applied to a development roller (not shown). Process control unit 51 may change the voltage applied to the developing roller (hereinafter also referred to as “developing voltage”) according to the atmospheric pressure at the location where MFP 100 is installed.

  The transfer voltage control unit 55 controls a voltage applied to a transfer roller (not shown). Process control unit 51 may change the voltage applied to the transfer roller (hereinafter also referred to as “transfer voltage”) in accordance with the atmospheric pressure of the place where MFP 100 is installed.

<4. Setting standard values in process design>
FIG. 5 is a diagram schematically showing an example of the correspondence between the set values of the charging voltage, the developing voltage, and the transfer voltage and the atmospheric pressure at the place where the MFP 100 is installed. Data specifying the table shown in FIG. 5 is stored in, for example, the memory 512 (see FIG. 3).

  In the table of FIG. 5, each of the set values of the charging voltage, the developing voltage, and the transfer voltage corresponds to each of two or more atmospheric pressure values (1.00 atm, 0.99 atm, 0.98 atm,...). ing. Each of the set values of the charging voltage, the developing voltage, and the transfer voltage is specified based on the reference value. The method for setting each reference value will be described below.

A. Charging Voltage If the charging voltage is smaller than an appropriate value, the charging potential of the photoconductor 41 is lowered, which may cause so-called “background fogging”. If the charging voltage is larger than an appropriate value, background fogging does not occur, but the amount of discharge between the photoconductor 41 and the charging roller 42 increases. Thereby, the depletion speed of the photoconductor 41 is increased, and the life of the photoconductor 41 is shortened. For this reason, the charging voltage of the charging roller 42 needs to be set to an appropriate value according to the state of the photoconductor 41 (temperature, humidity, pressure, film thickness of the photoconductor 41).

  When the temperature and / or humidity in the vicinity of the photoconductor 41 detected by the temperature / humidity detector 53 changes by a certain value or more, and / or the film thickness detector 52 decreases the film thickness by a certain amount. When it is determined that the charging voltage is seen, charging voltage determination control is performed. In the charging voltage determination control, the setting value of the charging voltage is specified by correcting a reference value set in advance for the charging voltage of the charging roller 42 according to the environment. The reference value can be corrected according to temperature, humidity, film thickness, and / or pressure.

FIG. 6 is a diagram for explaining an example of a reference value setting mode.
In the graph of FIG. 6, the horizontal axis indicates the voltage value applied to the charging roller 42, and the vertical axis indicates the current value flowing through the charging roller 42. As shown in FIG. 6, the current and voltage in the charging roller 42 when a relatively low voltage (about 600 V to 900 V) is applied and when a relatively high voltage (about 2100 V to 2200 V) is applied. The behavior of is different. In FIG. 6, the behavior in a relatively low voltage range is approximated by a line L1, and the behavior in a relatively high voltage range is approximated by a line L2. The approximate expression (1) for specifying the line L1 and the approximate expression (2) for specifying the line L2 are, for example, voltages when two or more different voltages within a corresponding voltage range are applied. And the least square method using the current values.

  The boundary between changes in the current and voltage behavior of the charging roller 42 is considered to be the intersection of the line L1 and the line L2. From this, the voltage at the intersection is estimated as a charging voltage (discharge start voltage) corresponding to the start of discharge of the photoconductor 41.

  The behavior of the current and voltage of the charging roller 42 varies depending on temperature, humidity, film thickness, and atmospheric pressure. In particular, in the graph of FIG. 6, the behavior indicated by the line L2 changes greatly.

  FIG. 7 is a diagram for explaining changes in the behavior of the current and voltage of the charging roller 42 when the atmospheric pressure at the place where the MFP 100 is installed changes. In FIG. 7, the behavior at 0.90 atm is indicated by a solid line, and the behavior at 1.00 atm is indicated by a one-dot chain line. As shown in FIG. 7, when the atmospheric pressure decreases, the rate of change of current with respect to the voltage in a relatively high voltage range increases.

  As understood from FIG. 7, the behavior of the current and voltage of the charging roller 42 changes according to the change in the atmospheric pressure. Due to this change in behavior, the discharge start voltage determined from the intersection of the two approximate lines changes due to the change in atmospheric pressure. In FIG. 7, the discharge start voltage at 0.90 atm is indicated by the discharge start voltage E1, and the discharge start voltage at 1.00 atm is indicated by the discharge start voltage E2.

  In MFP 100, the discharge start voltage obtained in a reference temperature, humidity, film thickness, and atmospheric pressure environment is treated as a reference value for the charging voltage. The process control unit 51 sets the charging voltage of the charging roller 42 under the environment by correcting the reference value according to the environment of the MFP 100. The atmospheric pressure at which the reference value is set is, for example, 1.00 atm. FIG. 5 shows an example of an aspect of setting the charging voltage in accordance with the atmospheric pressure at which MFP 100 is installed.

  In MFP 100, the range in which the discharge start voltage of photoconductor 41 to be used falls is confirmed in advance. Although the discharge start voltage varies depending on the temperature, humidity, atmospheric pressure, and film thickness of the photoconductor 41, the voltage applied to specify the approximate expression (1) and the approximate expression (2) depends on the fluctuation. It is preferable to be out of range.

  The CPU 511 may estimate the atmospheric pressure from the rate of change in current with respect to change in voltage in the charging roller 42 based on the relationship shown in FIG. In this case, the voltage applied for estimating the atmospheric pressure is preferably higher than the discharge start voltage. This is because, as shown in FIG. 7, the change in the rate of change of the current due to the change in the atmospheric pressure is larger in the range where the voltage is higher than the discharge start voltage than in the range where the voltage is lower than the discharge start voltage.

  The memory 512 of the MFP 100 stores the relationship between voltage and current (for example, the slope of a straight line as shown in FIG. 7) in a range where the voltage is higher than the discharge start voltage for each atmospheric pressure. The CPU 511 estimates the atmospheric pressure using the current detected when a voltage is applied to the charging roller 42 and the relationship (inclination) stored for each atmospheric pressure. Note that the relationship need not be stored in a storage device in the MFP 100 as long as the relationship is stored in a storage device accessible by the CPU 511.

B. Developing Voltage A bias voltage obtained by superimposing an alternating current (AC) voltage on a direct current (DC) voltage is applied to the developing roller as a developing voltage. Of the applied voltage, it is the AC voltage that needs to be corrected by the atmospheric pressure. Since the DC voltage affects the image density, it is not normally changed by the atmospheric pressure. A certain value is set as the AC voltage in order to improve the image quality. When the atmospheric pressure decreases, it is assumed that discharge noise occurs. For this reason, when the atmospheric pressure decreases, the AC voltage is lowered so that discharge noise does not occur even if the image quality is slightly reduced.

  The “reference value” for the development voltage shown in FIG. 5 is an AC voltage in the development voltage (hereinafter also referred to as “development AC voltage”). In MFP 100, the development AC voltage is not basically determined by the control each time. Therefore, an appropriate value is set as the “reference value” of the development AC voltage at 1.00 atm. The reference value is corrected according to the atmospheric pressure, for example, as shown in FIG.

C. Transfer Voltage MFP 100 employs an ATVC control method (abbreviation for Active Transfer Voltage Control) in order to cope with endurance fluctuations and environmental fluctuations of resistance values of the primary transfer means and the intermediate transfer body in setting the transfer voltage. The ATVC performs constant current control on the primary transfer portion with a preset value for the non-image portion on the photoconductor 41, and changes the resistance of the primary transfer portion by the fluctuation of the voltage value generated at this time. Detect. Thereafter, ATVC performs constant voltage control using the result of calculating the previously detected voltage value during image formation. The transfer voltage set by the ATVC control is stored as a “reference value” in the process control unit 51. ATVC is performed when temperature and / or humidity changes. As shown in the table of FIG. 5, the set value of the transfer voltage can be specified by correcting the reference value according to the atmospheric pressure.

<5. Process flow>
FIG. 8 is a flowchart of processing executed by the process control unit 51 (FIG. 3) to realize process design in accordance with the atmospheric pressure of the place where the MFP 100 is installed. The processing in FIG. 8 is realized by the CPU 511 executing a program stored in the memory 512, for example.

  As shown in FIG. 8, in step S <b> 1, the CPU 511 applies a test voltage (here, sin wave, frequency 1.2 kHz, Vpp 1800 V, Vc−600 V) to the charging roller 42. Here, “Vc” means the center value of the output of the AC voltage. The value of the test voltage in step S1 is an example and may be changed. Thereafter, the control proceeds to step S2.

  In step S <b> 2, the CPU 511 acquires, from the current detection unit 43, the current that has flowed through the charging roller 42 when the voltage is applied in step S <b> 1. Thereafter, the control proceeds to step S3.

  In step S <b> 3, the CPU 511 acquires the film thickness information of the photoconductor 41 from the film thickness detection unit 52. Thereafter, the control proceeds to step S4.

  In step S <b> 4, the CPU 511 acquires temperature and humidity from the temperature / humidity detection unit 53. Thereafter, the control proceeds to step S5.

  In step S5, the CPU 511 acquires the estimated value of the atmospheric pressure corresponding to the film thickness, temperature, and humidity acquired in steps S3 to S4 from the table shown in FIG. Estimate the atmospheric pressure of your environment. Thereafter, the control proceeds to step S6.

  In step S6, the CPU 511 reads the charging voltage, the developing voltage, and the transfer voltage corresponding to the atmospheric pressure estimated in step S5 from the table shown in FIG. Thereafter, the control proceeds to step S7.

  In step S7, the CPU 511 sets the control setting values of the charging voltage supply unit 44, the development voltage control unit 54, and the transfer voltage control unit 55 for the charging voltage, the development voltage, and the transfer voltage acquired in step S6, respectively. To update. Thereafter, the process of FIG. 8 ends.

  For example, a case where the current value acquired in step S2 is 1300 μA will be described. The film thickness information acquired in step S3 is “40.0 μm”, the temperature acquired in step S4 is “10 ° C.”, and the humidity acquired in step S4 is “10% RH”. And In the table of FIG. 4, the atmospheric pressure corresponding to the film thickness information “40.0 μm”, the temperature “10 ° C.”, and the humidity “10% RH” is “0.99 atm”. As a result, the CPU 511 of the process control unit 51 estimates in step S5 that the atmospheric pressure at the place where the MFP 100 is installed is “0.99 atm”. Thereafter, in step S6, the CPU 511 reads out the charging voltage, the developing voltage (developing AC voltage), and the transfer voltage corresponding to the atmospheric pressure “0.99 atm” from the table of FIG. Thereafter, in step S7, the CPU 511 controls the charging voltage supply unit 44, the development voltage control unit 54, and the transfer voltage control unit 55 to control the charging voltage, the development voltage, and the transfer voltage read in step S6, respectively. Instruct them to aim.

  According to the processing of FIG. 8 described above, feedback control of the charging voltage, the developing voltage, and the transfer voltage is realized according to the detected value such as temperature. Thereby, for example, an image defect due to a setting error in the atmospheric pressure (elevation) information of the worker can be reliably prevented.

  The description so far has described the case of AC charging in MFP 100, but the principle is the same in the case of DC charging in the image forming apparatus. Therefore, the CPU 511 can estimate the atmospheric pressure by the same method as described above.

  As described with reference to FIG. 7, the atmospheric pressure can also be obtained from the rate of change in current with respect to change in voltage in the charging roller 42. The CPU 511 may estimate the atmospheric pressure from such a change in the ratio. Furthermore, the atmospheric pressure estimated from the film thickness, temperature, and humidity of the photoconductor 41 may be corrected by the atmospheric pressure estimated from the rate of change in current with respect to the change in voltage in the charging roller 42.

  The atmospheric pressure may be associated with a current value when a specific voltage is applied to the charging roller 42 in addition to the film thickness, temperature, and humidity of the photoconductor 41 shown in FIG. In such a case, the CPU 511 estimates the atmospheric pressure based on the current value in addition to the film thickness, temperature, and humidity in step S5 of FIG. An example of the “specific voltage” is the “test voltage” described for step S1.

<6. Timing of changing process settings>
The update of the charging voltage, development voltage, and transfer voltage control targets described with reference to FIG. 8 is executed as appropriate. Below, the timing at which the control target is updated will be exemplified.

A. When New Photoconductor 41 is Used In MFP 100, when photoconductor 41 is new, the film thickness of photoconductor 41 is an initial value. Therefore, the film thickness of the photoconductor 41 can be acquired even if the MFP 100 does not include a sensor for measuring the film thickness. The memory 512 stores in advance an initial value of the film thickness of the photoconductor 41 as “initial film thickness”.

  The CPU 511 may execute the control of FIG. 8 when a new photoconductor 41 is used for the first time. As a method for detecting whether or not the photoconductor 41 is new, for example, the following two methods can be cited.

  Method 1: A fuse is attached to the photoreceptor unit including the photoreceptor 41, and the fuse is blown when the photoreceptor 41 is used for the first time. The CPU 511 determines whether or not the fuse is blown by a known method (for example, an electrical method), and determines whether or not the photoconductor 41 is new based on the result of the determination.

  Method 2: The photosensitive unit including the photosensitive member 41 is provided with an element for storing the number of printed sheets such as an IC chip. The CPU 511 reads the number of printed sheets stored in the element by a known method. The CPU 511 determines that the photoconductor 41 is new when the number of printed sheets stored in the element is 0, and determines that the photoconductor 41 is not new when the number is 1 or more.

B. When power on the MFP 100 is started The altitude used when the MFP 100 is installed at the user's location is determined. From this, the MFP 100 executes the processing of FIG. 8 when installation at the (new) use place of the user is started.

  In order to determine that MFP 100 has been installed at the user's location, CPU 511 detects, for example, that power of MFP 100 has been inserted into an outlet (commercial power supply port). Although it is possible that the power source is inserted into the outlet other than when the machine is installed, if it is detected that the power source is inserted into the outlet, at least the timing when it is used for the first time after the machine is installed can be detected.

  When the power supply is inserted into an outlet, power is supplied to the control board (a circuit board on which the CPU 511 and the like are mounted) in the MFP 100. The CPU 511 determines that the power source has been inserted into the outlet when the control board is energized.

  When the MFP 100 is transferred to an area where the altitude is different from the past use place, or when there is a period when the MFP 100 is not used so much as the season changes, the pressure of the place where the MFP 100 is installed is changed before or after the transfer or the previous time. May have changed from the use of. Even in such a case, the change in the electrical behavior of the charging roller 42 and the like due to such a change in atmospheric pressure can be covered by executing the process of FIG. 8 when the power source is inserted into the outlet. .

C. When the power is turned on The CPU 511 may execute the control of FIG. 8 every time the power is turned on (the energization of the CPU 511 is started). When the power is turned on, the MFP 100 normally generates a standby time until the fixing temperature becomes ready. The CPU 511 can execute the control of FIG. 8 during the standby time.

  In such a case, even if the atmospheric pressure changes with the power supply of the MFP 100 being inserted into the outlet, the CPU 511 can control the process of the MFP 100 according to the change in the atmospheric pressure.

D. After a certain period of time has elapsed since the last image formation The CPU 511 may execute the process of FIG. 8 on the condition that a certain period has elapsed since the last image formation in the MFP 100.

  That is, in MFP 100, each time an image forming operation (printing operation) is executed, the date of the operation may be stored in a given storage device (for example, memory 512). For example, when the power is turned on, the CPU 511 reads the “date of operation” stored in the storage device. Thereafter, when the CPU 511 determines that a certain period has elapsed from the day of the operation, the CPU 511 executes the process of FIG. As a result, even when the image forming operation is not performed in the MFP 100 for a certain period or more and the atmospheric pressure at the installation location of the MFP 100 changes during that period, the CPU 511 controls the process according to the change in the atmospheric pressure. it can.

  In the present embodiment described above, MFP 100 estimates the atmospheric pressure at the location where MFP 100 is installed from temperature, humidity, and film thickness of photoconductor 41, and controls the process according to the estimated atmospheric pressure. To do. In MFP 100, the temperature, humidity, and film thickness of photoconductor 41 are detected not only for the purpose of estimating atmospheric pressure but also for controlling image formation.

  The temperature is detected, for example, for determining whether there is an abnormality in the image forming unit 40. When the image forming unit 40 becomes hot due to a malfunction of the cooling fan or the like, the image forming operation is interrupted.

  Humidity is detected, for example, for process control. The degree of moisture absorption of the printing paper can change according to the humidity of the MFP 100 installation location. Thus, in MFP 100, the image density can be adjusted according to the humidity.

The film thickness of the photoconductor 41 is detected, for example, to notify the replacement timing of the photoconductor 41.
In MFP 100, the atmospheric pressure is estimated using temperature, humidity, and film thickness of photoconductor 41 that are detected for purposes other than atmospheric pressure estimation. As a result, the MFP 100 can perform process control according to changes in atmospheric pressure while suppressing the manufacturing cost.

  Each embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. In addition, the invention described in the embodiment and each modification is intended to be carried out independently or in combination as much as possible.

  40 Image forming section, 41 Photoconductor, 42 Charging roller, 43 Current detection section, 44 Charging voltage supply section, 50 Printer control section, 51 Process control section, 52 Film thickness detection section, 53 Temperature / humidity detection section, 54 Development voltage control Part, 55 transfer voltage control part, 100 MFP, 511 CPU, 512 memory.

Claims (11)

An image forming apparatus,
A first acquisition unit configured to acquire a film thickness of the photoreceptor;
A second acquisition unit configured to acquire temperature and humidity;
Based on the film thickness of the photoconductor acquired by the first acquisition unit and the temperature and humidity acquired by the second acquisition unit, the estimated value of the atmospheric pressure at the place where the image forming apparatus is installed And a control unit configured to identify
The image forming apparatus, wherein the control unit is configured to control an image forming process in the image forming apparatus based on the estimated value. A charging roller for charging the photoconductor;
The control unit further specifies an estimated value of the atmospheric pressure of the place where the image forming apparatus is installed based on a ratio of a change in current flowing in the charging roller with respect to a change in voltage applied to the charging roller. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to. An image forming apparatus,
A photoreceptor,
A charging roller for charging the photoreceptor;
Control configured to identify an estimated value of the atmospheric pressure at the location where the image forming apparatus is installed based on the rate of change in the current flowing through the charging roller with respect to the change in voltage applied to the charging roller With
The image forming apparatus, wherein the control unit is configured to control an image forming process in the image forming apparatus based on the estimated value. The charging roller further includes a voltage supply unit configured to supply a voltage obtained by superimposing an AC voltage on a DC voltage,
4. The image forming apparatus according to claim 2, wherein a voltage applied to the charging roller is higher than a voltage at which discharge starts in the photosensitive member charged by the charging roller. 5.   5. The control unit according to claim 1, wherein the control unit is configured to control the image forming process based on the estimated value when the photoconductor is used for the first time. 6. Image forming apparatus.   6. The control unit according to claim 1, wherein the control unit is configured to control the image forming process based on the estimated value when energization of a substrate on which the control unit is mounted is started. 7. The image forming apparatus according to claim 1.   7. The control unit according to claim 1, wherein the control unit is configured to control the image forming process based on the estimated value when energization of the control unit is started. The image forming apparatus described in 1.   The control unit is configured to control the image forming process based on the estimated value when it is detected that a certain period has elapsed since the previous image formation in the image forming apparatus. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the control of the image forming process includes control of at least one of a charging voltage, a developing voltage, and a transfer voltage. An image forming apparatus control method comprising:
Obtaining the film thickness of the photoreceptor, and the temperature and humidity of the place where the image forming apparatus is installed;
Identifying an estimated value of the atmospheric pressure of the place where the image forming apparatus is installed based on the film thickness of the photoconductor, the temperature and the humidity;
Controlling the image forming process in the image forming apparatus based on the estimated value. An image forming apparatus control method comprising:
Based on the rate of change in the current flowing through the charging roller with respect to the change in voltage applied to the charging roller for charging the photosensitive member, the estimated value of the atmospheric pressure at the location where the image forming apparatus is installed is specified Steps,
Controlling the image forming process in the image forming apparatus based on the estimated value.

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