JP6728800B2 - Image forming apparatus and control method thereof - Google Patents

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 is 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”) utilizing a phenomenon of discharge is used for charging, developing, and transferring. The discharge mode can change depending on the atmospheric pressure. The design of the image forming process usually 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 inputs the atmospheric pressure incorrectly, an error may occur in the process design. Japanese Patent Laying-Open No. 06-130770 (Patent Document 1) discloses an image forming apparatus including an element dedicated to pressure detection in order to more appropriately design a process design.

JP, 06-130770, A

However, according to the technique disclosed in Patent Document 1, costs for elements for detecting atmospheric pressure are added in manufacturing the image forming apparatus.

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

According to an aspect of the present disclosure, an image forming apparatus provided by the present disclosure is configured to obtain a first acquisition unit configured to obtain a film thickness of a photoconductor and temperature and humidity. Based on the second acquisition unit, the film thickness of the photoconductor 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 determined. And a controller configured to identify the estimated value of atmospheric pressure. The control unit is configured to control the 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 specify the estimated value of the atmospheric pressure at the place where the image forming apparatus is installed, based on the ratio of the change in the current flowing through the charging roller to the change in the voltage applied to the charging roller. Has been done.

According to another aspect of the present disclosure, an image forming apparatus provided by the present disclosure includes a photoconductor, a charging roller for charging the photoconductor, and a charging roller for changing a voltage applied to the charging roller. And a controller configured to specify an estimated value of the atmospheric pressure at the place where the image forming apparatus is installed, based on the rate of change of the current. The control unit is configured to control the 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 at the photoconductor charged by the charging roller.

Preferably, 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.

Preferably, the control unit is configured to control the image forming process based on the estimated value when energization of the board 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 the power supply to 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 of controlling an image forming apparatus includes a step of acquiring a film thickness of a photoconductor, a temperature and a humidity at a place where the image forming device is installed, and a film thickness of the photoconductor. , Specifying an estimated value of the atmospheric pressure of the place where the image forming apparatus is installed based on the temperature and humidity, and controlling an image forming process in the image forming apparatus based on the estimated value.

According to yet another aspect of the present disclosure, a control method for 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. The method includes the steps of specifying an estimated value of the atmospheric pressure at the place where the forming apparatus is installed, and controlling the 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.

It is a figure which shows the specific example of the external appearance of one embodiment of an image forming apparatus. It is a figure which shows the specific example of the hardware constitutions of MFP. FIG. 3 is a diagram illustrating a detailed configuration of the printer in FIG. 2. It is a figure which shows typically an example of the table utilized for control of MFP. FIG. 6 is a diagram schematically showing an example of correspondences between set values of a charging voltage, a developing voltage, and a transfer voltage, and atmospheric pressure at a place where the MFP is installed. It is a figure for explaining an example of a mode of setting a standard value. FIG. 6 is a diagram for explaining changes in current and voltage behavior of the charging roller when the atmospheric pressure at the place where the MFP is installed changes. 6 is a flowchart of a process executed to realize a process design according to the atmospheric pressure of the place where the MFP is installed.

An embodiment of an information processing apparatus will be described below with reference to the drawings. In the following description, the same parts and components are designated 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 device>
FIG. 1 is a diagram showing a specific example of the external appearance of an embodiment of an image forming apparatus. As shown in FIG. 1, MFP 100, which is 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 that has a combination of these functions.

<2. Hardware configuration>
FIG. 2 is a diagram showing 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 which is an arithmetic unit 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 print sheet, a display of information and an operation input to the MFP 100. An operation panel 15 including a touch panel for receiving and 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 removable from the MFP 100.

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

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 is in contact with the photoconductor 41, and the voltage required for image formation is applied from the charging voltage supply unit 44. The charging voltage supply unit 44 supplies, for example, to the charging roller 42 a voltage in which a direct current (DC: Direct Current) voltage is superimposed with an alternating current (AC: Alternate Current) voltage. When a voltage is applied to the charging roller 42 from the charging voltage supply unit 44, a potential difference is generated between the surface of the charging roller 42 and the photoconductor 41.

When the potential difference between the surface of the charging roller 42 and the photoconductor 41 becomes equal to or larger than a predetermined potential difference determined by Paschen's law, discharge occurs, and the photoconductor 41 is charged. An electric current flows due to the movement of charges between the charging roller 42 and the charged photoconductor 41. The current detector 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 determined by the environment in which the MFP 100 is installed (for example, temperature, Humidity, atmospheric pressure) and the film thickness of the photoconductor 41. From this, based on the current value and the voltage value, the temperature and humidity at the place where the MFP 100 is installed, and the film thickness of the photoconductor 41, the atmospheric pressure at 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 developing 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 a program executed by the CPU 511 and various data. An example of the data stored in the memory 512 is a table for specifying the predicted value of the atmospheric pressure at the place where the MFP 100 is installed. FIG. 4 is a diagram schematically showing 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 the 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) Atmospheric 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 atmospheric pressure of 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 atmospheric pressure.

The prediction of the atmospheric pressure is performed, for example, by acquiring the three types of values (1) to (3) mentioned with reference to the table of FIG. 4 and by determining the atmospheric pressures associated with the three types of acquired values. Including getting from a table. The atmospheric pressure value thus obtained is an example of the predicted atmospheric pressure value.

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 and the discharge current increase. Further, due to changes in the behavior of peeling discharge that occurs when peeling an object that is in contact with a dielectric or the like, a photoreceptor (photoconductor drum), an intermediate transfer body, a transfer body transport body (for example, a transfer drum), or these The toner and/or the transfer material (for example, transfer paper) on the upper side is excessively charged and discharged, which may cause image failure, transfer failure, transfer material peeling failure, and cleaning failure. In order to reliably avoid the occurrence of such a problem, the process control unit 51 determines the voltage applied to the charging roller 42 by the charging voltage supply unit 44 (hereinafter, also referred to as “charging voltage”) according to the predicted value of the atmospheric pressure. (I.e.), and further adjusts the output values relating to development and transfer (not shown) in the MFP 100. The method of adjusting the output values related to charging, development, and transfer will be described later.

The film thickness detection unit 52 acquires the film thickness of the photoconductor 41. In one example, the film thickness detection unit 52 acquires the film thickness of the photoconductor 41 based on the 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 detection unit 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, a sensor sold by Fisherscope or Keyence).

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

Film thickness T=initial film thickness TS-amount of wear WP per sheet printed×printed sheet number NP (1)
Film thickness T=initial film thickness TS-1 wear amount WR per rotation×rotation speed NR (2)
The “initial film thickness TS” is the initial film thickness of the photoconductor 41. The “amount of wear loss WP per print” is the amount of wear of the photoconductor 41 when printing one sheet of paper in the MFP 100. “Printed sheet number NP” is the number of sheets printed by the MFP 100. The “abrasion amount WR per rotation” is the amount of wear of the photoconductor 41 per one revolution of the photoconductor 41. The “revolution number NR” is the number of rotations of the photoconductor 41. The memory 512 stores data that specifies the "amount of wear WP per print" and/or "amount of wear WR per rotation". In the MFP 100, the “printed sheet number NP” and/or the “rotation number NR” of the photoconductor 41 are counted and stored in the memory 512. The “initial film thickness TS” is stored in the memory 512. The process control unit 51 reads an appropriate value from the memory 512 and calculates the film thickness T according to Expression (1) or Expression (2).

The temperature/humidity detection unit 53 acquires the temperature and humidity of the place where the MFP 100 is installed. In one example, the temperature/humidity detection unit 53 acquires the temperature and/or humidity of the location based on the 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 location based on the physical quantity detected by the MFP 100.

The developing voltage controller 54 controls the voltage applied to a developing roller (not shown). The 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 place where the MFP 100 is installed.

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

<4. Setting reference 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 of the place where MFP 100 is installed. The data specifying the table shown in FIG. 5 is stored in the memory 512 (see FIG. 3), for example.

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

A. Charging Voltage When the charging voltage is lower than an appropriate value, the charging potential of the photoconductor 41 becomes low, which may cause so-called “background fog”. When the charging voltage is higher than an appropriate value, the background fog does not occur, but the amount of discharge between the photoconductor 41 and the charging roller 42 increases. As a result, the wear rate of the photoconductor 41 is increased, and the life of the photoconductor 41 is shortened. Therefore, 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, atmospheric 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 detecting unit 53 changes by a certain value or more, and/or the film thickness detecting unit 52 reduces the film thickness by a certain amount. When it is determined that is found, the charging voltage determination control is performed. In the charging voltage determination control, the preset value of the charging voltage of the charging roller 42 is corrected according to the environment to specify the setting value of the charging voltage. The reference value can be corrected according to temperature, humidity, film thickness, and/or atmospheric 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 represents the voltage value applied to the charging roller 42, and the vertical axis represents the current value flowing in the charging roller 42. As shown in FIG. 6, the current and voltage in the charging roller 42 are different between 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. Behave differently. In FIG. 6, the behavior in the relatively low voltage range is approximated by the line L1, and the behavior in the relatively high voltage range is approximated by the 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. It is obtained by the least squares method using the respective values of and.

The boundary of the change 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 to be the 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 changes depending on the temperature, humidity, film thickness, and atmospheric pressure. In particular, in the graph of FIG. 6, the behavior indicated by the line L2 changes significantly.

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

As understood from FIG. 7, the behavior of the current and voltage of the charging roller 42 changes due to the change of the atmospheric pressure. Due to this change in behavior, the discharge start voltage obtained 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 shown by the discharge start voltage E1, and the discharge start voltage at 1.00 atm is shown by the discharge start voltage E2.

In the MFP 100, the discharge start voltage obtained under the reference temperature, humidity, film thickness, and atmospheric pressure environment is treated as the reference value of 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 1.00 atm, for example. FIG. 5 shows an example of a mode of setting the charging voltage according to the atmospheric pressure in which the MFP 100 is installed.

In the MFP 100, it has been previously confirmed as to what range the discharge start voltage of the photoconductor 41 to be used falls. The discharge start voltage varies depending on the temperature, the humidity, the atmospheric pressure, and the film thickness of the photoconductor 41. However, the voltage applied to identify the approximate expression (1) and the approximate expression (2) does not change. It is preferably outside the range.

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

The memory 512 of the MFP 100 stores the relationship between the voltage and the current in the range where the voltage is higher than the discharge start voltage (for example, the slope of the straight line as shown in FIG. 7) 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 does not need to be stored in the storage device in MFP 100 as long as it is stored in the storage device accessible by CPU 511.

B. Developing Voltage To the developing roller, a bias voltage is applied as a developing voltage, which is a direct current (DC: Direct Current) voltage superimposed with an alternating current (AC: Alternate Current) voltage. Of the applied voltages, it is the AC voltage that needs to be corrected by the atmospheric pressure. Since the DC voltage affects the image density, it is usually not changed by atmospheric pressure. A certain value is set as the AC voltage in order to improve the image quality. When the atmospheric pressure drops, it is expected that discharge noise will occur. Therefore, when the atmospheric pressure drops, the AC voltage is lowered so that discharge noise does not occur even if the image quality is slightly degraded.

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

C. Transfer Voltage In the MFP 100, the ATVC control method (abbreviation of Active Transfer Voltage Control) is adopted in the setting of the transfer voltage in order to cope with the endurance variation and the environmental variation of the resistance value of the primary transfer unit and the intermediate transfer member. The ATVC performs constant current control on the primary transfer portion at a preset value for the non-image portion on the photoconductor 41, and changes the resistance of the primary transfer portion due to the change in the voltage value generated at this time. Detect. After that, at the time of image formation, the ATVC performs constant voltage control using the result of arithmetic processing of the voltage value detected previously. The transfer voltage set by the ATVC control is stored as a “reference value” in the process control unit 51. ATVC is performed when the 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 a process design according to the atmospheric pressure of the place where the MFP 100 is installed. The process of FIG. 8 is implemented, for example, by the CPU 511 executing a program stored in the memory 512.

As shown in FIG. 8, in step S1, 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 S2, the CPU 511 acquires from the current detection unit 43 the current flowing through the charging roller 42 in the voltage application in step S1. Thereafter, the control proceeds to step S3.

In step S3, 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 S4, 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, the temperature, and the humidity acquired in steps S3 to S4 from the table shown in FIG. Estimate the atmospheric pressure in the existing 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 voltage set values of the charging voltage supply unit 44, the developing voltage control unit 54, and the transfer voltage control unit 55 to the charging voltage, the developing voltage, and the transfer voltage acquired in step S6. Instruct to update. After that, 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”. Accordingly, the CPU 511 of the process control unit 51 estimates that the atmospheric pressure of the place where the MFP 100 is installed is “0.99 atm” in step S5. After that, in step S6, the CPU 511 reads 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. After that, in step S7, the CPU 511 controls the charging voltage supply section 44, the developing voltage control section 54, and the transfer voltage control section 55 to control the charging voltage, the developing voltage, and the transfer voltage read in step S6. 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 the temperature. Thereby, for example, an image defect due to an error in setting the atmospheric pressure (elevation) information of the worker can be reliably prevented.

Although the above description has been given of the case of AC charging in the MFP 100, 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 at the charging roller 42. The CPU 511 may estimate the atmospheric pressure from such a change in the ratio. Further, the atmospheric pressure estimated from the film thickness of the photoconductor 41, the temperature, and the humidity may be corrected by the atmospheric pressure estimated from the ratio of the change of the current to the change of the voltage of the charging roller 42.

The atmospheric pressure may be associated with the 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, the temperature, and the humidity in step S5 of FIG. An example of the “specific voltage” is the “test voltage” described in step S1.

<6. Timing of changing process settings>
The update of the control target of the charging voltage, the developing voltage, and the transfer voltage described with reference to FIG. 8 is appropriately executed. Below, the timing at which the update of the control target is executed will be illustrated.

A. When a New Photoconductor 41 is Used In the MFP 100, when the photoconductor 41 is a new one, the film thickness of the 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. An initial value of the film thickness of the photoconductor 41 is stored in advance in the memory 512 as the “initial film thickness”.

The CPU 511 may execute the control of FIG. 8 when the new photoconductor 41 is used for the first time. The following two methods are available as methods for detecting whether or not the photoconductor 41 is new.

Method 1: A fuse is attached to the photoconductor unit including the photoconductor 41 so that the fuse is blown when the photoconductor 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 photoconductor unit including the photoconductor 41 is provided with an element such as an IC chip for storing the number of printed sheets. 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 prints stored in the element is 0, and determines that the photoconductor 41 is not new when the number of prints stored in the element is 0 or more.

B. When the power supply to the MFP 100 is started, the altitude used when the MFP 100 is installed in the place where the user uses it is determined. From this, the MFP 100 executes the process of FIG. 8 when the installation at the (new) use place of the user is started.

In order to determine that the MFP 100 is installed in the place where the user uses it, the CPU 511 detects, for example, that the power supply of the MFP 100 is inserted into an outlet (commercial power supply port). Although the power supply may be inserted into the outlet other than when the machine is installed, if the insertion of the power supply into the outlet is detected, at least the timing when the machine is first used can be detected.

When the power supply is inserted into the outlet, the control board (circuit board on which the CPU 511 and the like is mounted) of the MFP 100 is energized. The CPU 511 determines that the power supply is inserted into the outlet when the control board is energized.

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

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 waits until the fixing temperature reaches the ready state. The CPU 511 can execute the control of FIG. 8 during the standby time.

In such a case, even when the atmospheric pressure changes while the power source of the MFP 100 is still inserted in the outlet, the CPU 511 can control the process of the MFP 100 according to the change of the atmospheric pressure.

D. After a lapse of a fixed period from the final image formation, CPU 511 may execute the process of FIG. 8 on condition that the fixed period of time has elapsed from the final image formation in 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). The CPU 511 reads out the “operation day” stored in the storage device when the power is turned on, for example. After that, 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 if the image forming operation is not executed in the MFP 100 for a certain period of time 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 place where MFP 100 is installed from temperature, humidity, and the film thickness of photoconductor 41, and controls the process according to the estimated atmospheric pressure. To do. In the MFP 100, the temperature, the humidity, and the film thickness of the photoconductor 41 are detected for the purpose of controlling the image formation, in addition to the purpose of estimating the atmospheric pressure.

The temperature is detected to determine whether or not there is an abnormality in the image forming unit 40, for example. When the image forming unit 40 has a high temperature due to a malfunction of the cooling fan or the like, the image forming operation is interrupted.

Humidity is sensed for process control, for example. The degree of moisture absorption of the printing paper may change according to the humidity of the installation location of the MFP 100. From this, in the 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 time of the photoconductor 41.
The MFP 100 estimates the atmospheric pressure by using the temperature, the humidity, and the film thickness of the photoconductor 41, which are detected for purposes other than the estimation of the atmospheric pressure. As a result, the MFP 100 can control the process according to the change in atmospheric pressure while suppressing the manufacturing cost.

It should be considered that the embodiments disclosed this time are exemplifications in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope. In addition, the invention described in the embodiment and each modification is intended to be implemented singly or in combination as much as possible.

40 image forming unit, 41 photoconductor, 42 charging roller, 43 current detection unit, 44 charging voltage supply unit, 50 printer control unit, 51 process control unit, 52 film thickness detection unit, 53 temperature and humidity detection unit, 54 development voltage control Section, 55 transfer voltage control section, 100 MFP, 511 CPU, 512 memory.

Claims (10)

An image forming apparatus,
A first acquisition unit configured to acquire the film thickness of the photoreceptor,
A second acquisition unit configured to acquire temperature and humidity;
A third acquisition unit configured to acquire a current value generated in the charging roller based on a voltage applied to the charging roller for charging the photoconductor ,
Based on the film thickness of the photoreceptor obtained by the first obtaining unit, the temperature and humidity obtained by the second obtaining unit, and the current value obtained by the third obtaining unit , And a control unit configured to specify an estimated value of the atmospheric pressure of the place where the image forming apparatus is installed,
The image forming apparatus is configured such that the control unit controls an image forming process in the image forming apparatus based on the estimated value. The control unit further specifies an estimated value of atmospheric pressure at a place where the image forming apparatus is installed, based on a rate of change in current flowing through the charging roller with respect to change in voltage applied to the charging roller. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to: The control unit may calculate the estimated value of the atmospheric pressure specified 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 image forming according to claim 2, wherein the image formation is performed with the estimated value of the atmospheric pressure specified based on the rate of change of the current flowing through the charging roller with respect to the change of voltage applied to the charging roller. apparatus. The charging roller further comprises a voltage supply unit configured to supply a voltage obtained by superimposing an AC voltage on a DC voltage,
The image forming apparatus according to claim 2, wherein the voltage applied to the charging roller is higher than the voltage at which discharge starts at the photoconductor charged by the charging roller. 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. 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 board on which the control unit is mounted is started. The image forming apparatus according to claim 1. 7. 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 according to item 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 any one of claims 1 to 7. 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. A method of controlling an image forming apparatus, comprising:
Photoconductor film thickness, temperature and humidity of the location where the previous SL image forming apparatus is installed, as well as, obtaining a current value caused to the charging roller on the basis of the voltage applied to the charging roller for charging said photosensitive member Steps to
And the film thickness of the photosensitive member, and the temperature and the humidity, the steps of the charging based on the current value generated in the rollers, to identify an estimate of pressure of the location where the image forming apparatus is installed,
Controlling the image forming process in the image forming apparatus based on the estimated value.

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