JP5900151B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  The image forming apparatus is provided with a detachable unit (part). When the remaining amount of consumables constituting the unit is reduced or worn, as described in Patent Document 1, the unit An exchange has been made. In addition, after the replacement, various adjustment operations are performed in order to output a stable image.

  For example, in an image forming apparatus having an output paper density adjustment function, output paper density adjustment is performed when a unit from transfer to fixing is replaced. In the output paper density adjustment, a gradation pattern image (referred to as a γ correction chart) including a plurality of density patches is formed on the paper, and the density of each patch on the output paper is measured to adjust the density. It is. By adjusting the output paper density, it is possible to correct the process characteristics from transfer to fixing and the characteristics of the paper to be used. However, the implementation consumes time and paper.

JP 2008-203212 A

  By the way, in recent years, an image forming apparatus has been proposed in which a plurality of types of fixing devices having different fixing characteristics are detachable, and the fixing devices are replaced according to printing applications to improve image quality. In such an image forming apparatus, the once removed fixing device is used again, that is, the same fixing device is used over and over again.

Unlike a unit that uses a member that is affected by humidity and deteriorates in a short time, such as a developing device, the fixing device has almost no influence on the image due to deterioration over time. Therefore, the fixing characteristics are almost the same when the fixing device is removed and remounted.
However, in the conventional image forming apparatus, even when the fixing unit that has already been adjusted is replaced and reattached, the output paper density is adjusted again after the replacement, and wasteful time and paper are consumed. there were.

  Patent Document 1 is a technique for notifying a user of the replacement time of consumables, and as described above, useless adjustment when the same unit is reused cannot be prevented.

  An object of the present invention is to prevent unnecessary adjustment from being performed when a unit that has been adjusted once is remounted in the image forming apparatus.

In order to solve the above-mentioned problem, the invention described in claim 1
The first unit that has almost no change in characteristics over time when not in use and the second unit that has changes in characteristics over time even when not in use can be attached and detached. An image forming apparatus including a configured printing unit,
A counter for counting the number of printed sheets in the printing means;
An adjusting unit that generates an adjustment value by performing output paper density adjustment for correcting process characteristics from transfer to fixing in the printing unit and characteristics of a sheet used in the printing unit ;
The adjustment value generated by the adjustment means, the count value of the counter when the adjustment value is generated, and the identification information of the first unit used for generating the adjustment value are stored in association with each other. Storage means for
When the first unit is replaced , the adjustment value and the count value corresponding to the identification information of the first unit mounted by the replacement are acquired from the storage unit, and the counter count value and the acquired value are acquired. Until the number of prints from the generation point of the adjustment value calculated based on the count value reaches a predetermined reference number, the characteristics of the printing unit are corrected using the acquired adjustment value,
Control means for generating a new adjustment value by the adjustment means when the second unit is replaced, and correcting the characteristics of the printing means using the generated adjustment value ;
Is provided.

The invention according to claim 2 is the invention according to claim 1 ,
The first unit is a fixing device.

The invention according to claim 3 is the invention according to claim 1 or 2 ,
The second unit is a developing device.

  According to the present invention, in the image forming apparatus, it is possible to prevent unnecessary adjustment when a unit that has been adjusted once is remounted.

1 is a schematic configuration diagram of an image forming apparatus. 2 is a functional block diagram of the image forming apparatus. FIG. It is a figure which shows the data storage structure of a non-volatile memory. It is a schematic block diagram of a color sensor. This is the size specification of the γ correction chart. It is an example of the chart for γ correction. It is a figure which shows the example of a data structure of the data for (gamma) correction. It is a figure which shows the data structure example of a paper category. It is a figure which shows an example of an individual setting screen. FIG. 10 is a diagram illustrating an example of a list screen of paper categories. It is a flowchart which shows the list display control process performed by the control part of FIG. 6 is a diagram illustrating a data structure of a tray paper profile. FIG. 6 is a diagram illustrating an example of an output paper density adjustment setting screen. FIG. FIG. 6 is a diagram illustrating an example of setting information for output paper density adjustment. 3 is a flowchart illustrating printer γ automatic generation processing executed by a control unit in FIG. 2. 3 is a flowchart illustrating printer γ automatic generation processing executed by a control unit in FIG. 2. It is a figure which shows an example of an output paper density | concentration adjustment screen. 3 is a flowchart showing a printer γ generation process executed by a control unit in FIG. 2. It is a flowchart which shows the exchange mode process performed by the control part of FIG.

  The configuration and operation of the image forming apparatus in this embodiment will be described in detail with reference to the drawings. In the present embodiment, a color image forming apparatus will be described as an example. However, the present invention is not limited to this, and the present invention can be realized by, for example, a monochrome image forming apparatus.

[Configuration of Image Forming Apparatus 10]
FIG. 1 shows a schematic configuration of the image forming apparatus 10. FIG. 2 is a functional block diagram of the image forming apparatus 10.
The image forming apparatus 10 is an electrophotographic digital printer, and includes a main body 11 and a relay unit (hereinafter, “RU”) 21.

  The main unit 11 includes a control board 1, an operation display unit 2, a scanner unit 3, a printing unit 4, a printer controller 5, and the like. Each unit is supplied with power by a power supply unit (not shown).

  The control board 1 includes a control unit 1a, a nonvolatile memory 1b, a reading processing unit 1c, a compression IC 1d, a DRAM control IC 1e, an image memory 1f, an expansion IC 1g, a writing processing unit 1h, and the like.

  The control unit 1a includes a CPU, a RAM, a ROM, and the like, reads various programs stored in the ROM or the nonvolatile memory 1b, expands them in the RAM, and executes various processes in cooperation with the expanded various programs. Then, each part of the image forming apparatus 10 is controlled. For example, the control unit 1a performs various processes including a printer γ automatic generation process, a printer γ generation process, and an exchange mode process, which will be described later, in cooperation with a program, and functions as an adjustment unit and a control unit.

The nonvolatile memory 1b is a storage unit configured by a rewritable nonvolatile memory, and stores various programs and various data.
In the present embodiment, as shown in FIG. 3, the non-volatile memory 1b includes a total counter storage area A10, a setting information storage area A11, and a γ correction data storage area as data storage areas for output paper density adjustment, which will be described later. A12, a paper category storage area A13, a tray paper profile storage area A14, a γ correction data saving area A15, and the like are provided.
The total counter storage area A10 is an area (counter) for counting the number of printed sheets in the printing unit 4 and storing the count value.
The setting information storage area A11 is an area for storing setting information (see FIG. 14) for output paper density adjustment described later.
The γ correction data storage area A12 is an area for storing γ correction data (see FIG. 7) described later. The γ correction data storage area A12 is an area accessed by the control unit 1a during printing by the printing unit 4.
The paper category storage area A13 is an area for storing a paper category (see FIG. 8) described later.
The tray paper profile storage area A14 is an area for storing a tray paper profile (see FIG. 12) described later.
The γ correction data saving area A15 is an area for saving γ correction data stored in the γ correction data storage area A12 in an exchange mode process described later.
The nonvolatile memory 1b stores image data for a γ correction chart (to be described later), size specifications, default correction values, γ correction data by an IDC sensor, and the like.

  The reading processing unit 1c receives an analog image signal output from the CCD 3a, and performs analog processing, shading processing, A / D conversion processing, and the like on the input analog image signal to generate digital image data. The read processing unit 1c outputs the generated image data to the compression IC 1d.

  The compression IC 1d receives the image data output from the reading processing unit 1c, performs compression processing on the input image data, and then outputs the image data to the DRAM control IC 1e.

The DRAM control IC 1e compresses the image data read by the reading processing unit 1c with the compression IC 1d, and stores the compressed image data with the compression memory 11f.
Further, the DRAM control IC 1e receives the compressed image data from the compression memory 11f, decompresses it with the decompression IC 1g, and stores the decompressed uncompressed image data with the page memory 12f. Further, the DRAM control IC 1e receives the uncompressed image data stored in the page memory 12f, and outputs the input uncompressed image data to the write processing unit 1h.

  The image memory 1f is constituted by a DRAM and includes a compression memory 11f and a page memory 12f. The compression memory 11f stores compressed image data. The page memory 12f temporarily stores uncompressed image data to be printed before printing.

  The decompression IC 1g performs decompression processing on the input compressed image data.

  The write processing unit 1 h generates print data based on the image data to be printed input from the DRAM control IC 1 e and outputs the print data to the print unit 4.

The operation display unit 2 includes an LCD (Liquid Crystal Display) 2a, an operation display control unit 2b, and the like.
The LCD 2a includes a touch panel that covers the LCD 2a. The operation display control unit 2b receives a display signal output from the control unit 1a, and displays various setting screens on the LCD 2a based on the input display signal. Further, the operation display control unit 2b inputs an operation signal generated by pressing an operation key group or a touch panel (not shown), and outputs the input operation signal to the control unit 1a.

  The scanner unit 3 includes a CCD 3a and a scanner control unit 3b that drives and controls the CCD 3a. The scanner unit 3 exposes and scans a document surface placed on a document table (not shown) by a light source, receives reflected light from the document surface, and photoelectrically converts the received reflected light by the CCD 3a to generate an analog image signal. To do. The scanner unit 3 outputs the generated analog image signal to the reading processing unit 1c.

The printing unit 4 includes a printer engine 4a and a printer control unit 4b that controls an image forming operation of the printer engine 4a.
The printer engine 4a includes the paper feeding unit 12, the image forming units 13 to 16, the intermediate transfer belt 17, the transfer roller 18, the fixing device 19 and the like shown in FIG. 1, and forms and forms a toner image on the paper. A series of image forming processes for fixing the toner image is performed. An IDC sensor 17 a is installed on the downstream side in the rotation direction of the intermediate transfer belt 17.

The paper feed unit 12 includes a plurality of paper feed trays, stores paper for each paper type, and feeds the stored paper through a predetermined transport path.
Each of the image forming units 13 to 16 includes an exposure device, a photosensitive drum, a charging device, a developing device, a primary transfer roller, and the like, and forms and carries a toner image of each color of YMCK on the photosensitive drum. Transfer onto the transfer belt 17 (primary transfer). The developing units of the image forming units 13 to 16 are units (second units) configured to be detachable from the main body unit 11 of the image forming apparatus 10. The intermediate transfer belt 17 rotates while carrying the transferred toner image.
The transfer roller 18 transfers the YMCK color toner images carried on the intermediate transfer belt 17 to a sheet (secondary transfer).

The fixing device 19 heats or pressurizes the toner images of each color of YMCK formed by being transferred onto the paper, and fixes the toner image on the paper. The paper on which the toner image is fixed is then conveyed to the RU 21.
Here, the fixing device 19 is a unit (first unit) configured to be detachable from the main body 11 of the image forming apparatus 10. There are two types of fixing device 19, a normal fixing device 191 and a special fixing device 192, one of which is attached to the main body 11. Here, in the present embodiment, the normal fixing device 191 is a fixing device for use when printing on paper different from the envelope. The special fixing device 192 is a dedicated envelope fixing device for use when printing on an envelope. The special fixing device 192 has a structure specialized for an envelope, for example, by reducing the thickness of the fixing roller so that wrinkles are less likely to occur. Therefore, when used for fixing paper other than the envelope, the special fixing device 192 has a large damage and costs. Get higher. Therefore, the special fixing unit 192 is used exclusively for printing for envelopes, and the normal fixing unit 191 is used exclusively for fixing sheets other than envelopes.

  A port 19 a serving as a fixing unit identification unit for identifying the type of the mounted fixing unit 19 is provided in the mounting unit of the fixing unit 19 in the main body 11. For example, when the normal fixing device 191 is attached, a HIGH signal is output as a fixing device identification signal to the printer control unit 4b via the port 19a. When the special fixing device 192 is attached, a LOW signal is output as a fixing device identification signal to the printer control unit 4b via the port 19a. The printer control unit 4b can recognize the fixing device mounted on the image forming apparatus 10 based on the fixing device identification signal.

An IDC (Image Density Control) is provided downstream of the intermediate transfer belt 17 in the rotation direction.
A sensor 17a is installed. The IDC sensor 17a outputs a voltage value obtained by reading the γ correction chart formed on the intermediate transfer belt 17 to the control unit 1a.

  The printer controller 5 includes a controller control CPU 5a, a LANIF 5b, a USB port 5c, a DRAM control IC 5d, and an image memory 5e.

The controller control CPU 5a comprehensively controls the operation of each unit of the printer controller 5.
The LANIF 5b is a communication interface for connecting to a LAN (Local Area Network) such as a NIC (Network Interface Card) or a modem, and receives image data transmitted from an external PC via the LAN. The LANIF 5b outputs the received image data to the DRAM control IC 5d.

  The USB port 5c inputs various data stored in the USB memory, and outputs the input various data to the controller control CPU 5a.

  The DRAM control IC 5d outputs the image data to the image memory 5e, and inputs the image data from the image memory 5e. The DRAM control IC 5d is connected to the DRAM control IC 1e of the control board 1 via a PCI bus, and outputs image data or various data to the DRAM control IC 1e.

  The image memory 5e is constituted by a DRAM and temporarily stores image data.

The RU 21 includes an RU control unit 21a, a color sensor 22, and the like. In addition, the RU 21 has a function of synchronizing with the conveyance speed of the sheet conveyed from the main body unit 11. Further, the RU 21 may have a function capable of performing various processes such as a punching process, a folding process, a glue application process, and a cutting process, that is, a so-called finisher function.
The RU control unit 21a includes a CPU, a RAM, a ROM, and the like, reads various programs stored in the ROM, expands them in the RAM, and controls each unit of the RU 21 in cooperation with the expanded various programs. Further, the RU control unit 21a is connected to the control unit 1a of the control board 1 through the printer control unit 4b so as to be able to perform data communication.

  As shown in FIG. 4, the color sensor 22 is a reflective sensor that includes an LED light source 221, a light receiving element 222, a lens 223, a lens holder 224, and the like, and γ formed on a sheet that passes over the sensor. The voltage value obtained by reading the correction chart (see FIG. 6) is output to the RU control unit 21a.

[Printer γ correction]
The printer γ correction is an image actually printed on a sheet based on values (input values) such as density and luminance of the input image input to the image forming apparatus 10 that are generated by the characteristics of the printing unit 4 and the input image. It means to correct the relative relationship with the density (output value) of. As described above, the image forming apparatus 10 includes the IDC sensor 17a and the color sensor 22, and can perform printer γ correction by two types of methods, an IDC sensor method and a color sensor method.

  In the printer γ correction by the IDC sensor method, the transfer characteristics in the printing unit 4 can be corrected. The transfer characteristics are process characteristics until the toner image is transferred (temporarily transferred) to the intermediate transfer belt 17 in the printing unit 4. In the IDC sensor system, a γ correction chart for an IDC sensor is formed on the intermediate transfer belt 17, and the color is measured by the IDC sensor 17a to obtain γ correction data (measurement value (density of the γ correction chart by the IDC sensor 17a) (density). Value) and related information). Then, γ data (γ correction table or function indicating the relationship between the input image and the output image in the print unit 4) is generated based on the γ correction data, and the printer γ correction is performed using the γ data during printing based on the job. Do. The image forming apparatus 10 generates five types of γ correction data according to the screen.

  In the color sensor type printer γ correction, process characteristics from transfer to fixing in the printing unit 4 can be corrected. In the color sensor method, characteristics specific to the paper to be used are also subject to correction. In the color sensor method, a γ correction chart (see FIG. 6) is formed on a sheet in the printing unit 4 and measured by the color sensor 22 of the RU 21 to obtain γ correction data (measured values of the γ correction chart by the color sensor 22). (Density value) and related information) are generated. Then, γ data is generated based on the γ correction data, and printer γ correction is performed using the γ data during printing based on the job. In the image forming apparatus 10, fifteen types of γ correction data are generated in accordance with a combination of a fixing device type, a screen, and a paper type (here, three types of plain paper, high-quality paper, and coated paper). Generating γ correction data using the color sensor 22 is called output paper density adjustment. Hereinafter, the output paper density adjustment will be described in detail.

FIG. 5 shows the size specification of the γ correction chart used for output paper density adjustment.
The setting of the size specification of the γ correction chart is preliminarily stored in the nonvolatile memory 1b. The γ correction chart includes a plurality of γ correction patches, and the γ correction patches are formed over a plurality of sheets. The size of the γ correction patch is determined by the performance of the color sensor 22 and the like. In general, the larger the paper size, the smaller the number of sheets used in the γ correction chart, and the smaller the paper size, the more paper is required. In this example, the sheet size required for the γ correction chart is associated with a total of three paper sizes of large, medium, and small sizes. For example, when the γ correction chart is formed on a paper (A4 paper) having a length of 297.0 mm in the sub-scanning direction (paper conveyance direction), since it is “medium size”, the “number of γ correction patches” is 32. The number of “sheets” is four.

FIG. 6 shows an example of a γ correction chart used for output paper density adjustment.
The γ correction chart shown in FIG. 6 is a γ correction chart formed on A4 paper. YMCK γ correction patches for each color are formed over a total of four sheets A4-1 to A4-4. Eight γ correction patches are formed for one A4 sheet, and a total of 32 patches are formed for four A4 sheets. The total number of γ correction patches for each color of YMCK is 32 × 4 colors = 128. The gradation values of the γ correction patches formed in the γ correction charts A4-1 to A4-4 are evenly distributed in A4-1 to A4-4 with the gradation 255 as the maximum, as shown in FIG. By evenly distributing the density, color reproducibility can be ensured, and chart dependency can be reduced or noise can be reduced.

  FIG. 7 shows an example of the data structure of the γ correction data generated by the output paper density adjustment in this embodiment. As shown in FIG. 7, the γ correction data includes “registration state”, “fixer type”, “paper category number”, “paper type”, “screen”, “adjustment point count value”, “update date”. , “Sensor measurement value”, “past sensor measurement value”, and the like.

In the “registration state”, any registration state of unregistered, registered, or readjustment mode is stored. Unregistered indicates that the “sensor measurement value” is not registered. Registration indicates that the “sensor measurement value” is registered. The readjustment mode indicates that since the image stabilization control has been performed, it is necessary to regenerate the “sensor measurement value”, that is, to adjust the output paper density again.
The “fixing device type” stores identification information (normal fixing device: 0, special fixing device: 1) for identifying the type of the fixing device used for generating the “sensor measurement value”. Here, the type of fixing device refers to a group of fixing devices having the same usage purpose and application.
The “paper category number” stores the registration number of the paper category (sensor correction data of the color sensor 22) used when the voltage value output from the color sensor 22 is converted into the density value. Details of the paper category will be described later.
The “paper type” stores information indicating the type of paper used for printing the γ correction chart for generating the “sensor measurement value”.
The “screen” stores information indicating the type of the screen used for printing the γ correction chart for generating the “sensor measurement value”.
The “adjustment time count value” stores information indicating the number of printed sheets (count value of the total counter) in the printing unit 4 at the time when the “sensor measurement value” is generated.
In the “update date”, the date on which the γ correction data is updated is stored.
In the “sensor measurement value”, the adjustment value generated by the output paper density adjustment, that is, the voltage value obtained by measuring the color correction chart by the color sensor 22 in the output paper density adjustment is converted into the density value. Stores the value. Using this “sensor measurement value”, γ data used for printer γ correction is generated.
“Past sensor measurement value” stores the sensor measurement value before update.

  The γ correction data generated by the output paper density adjustment is stored in the γ correction data storage area A12 of the nonvolatile memory 1b. That is, in the nonvolatile memory 1b, “sensor measurement value” that is an adjustment value generated by adjusting the output paper density and a count value of the number of printed sheets of the printing unit 4 at the time when the adjustment value is generated are “ The “adjustment time point count value” and the “fixing device type” that is identification information of the type of the fixing device used to generate the adjustment value are stored in association with each other.

Here, the paper category will be described.
The output paper density adjustment is performed by reading the γ correction chart formed on the paper with the color sensor 22. The reflectance of the color sensor 22 varies depending on the paper type. Therefore, in order to obtain an image with stable image quality, for example, it is necessary to correct the reading characteristics of the color sensor 22 that have changed due to sensor-specific changes such as replacement of the color sensor 22 and displacement, for each sheet. Therefore, the sensor characteristic is corrected, the sheet is conveyed from the sheet feeding unit 12, the voltage value obtained by reading the γ correction chart formed on the sheet by the color sensor 22, and the γ correction by the colorimeter or the like. The density values such as XYZ tristimulus values obtained by reading the chart are acquired and stored as sensor correction data in the paper category storage area A13 of the nonvolatile memory 1b. Since this sensor correction data is data depending on the paper, it is called “paper category”. Based on the paper category, a density conversion table or function for converting the voltage value of the sensor into a density value is generated, and γ correction data is generated using the density conversion table or function.

FIG. 8 shows an example of the data structure of the paper category. As shown in FIG. 8, the paper category includes a “patch colorimetric voltage value” that is a voltage value obtained by reading the γ correction chart formed on the paper by the color sensor 22, and a colorimeter or the like. “Density value”, which is a density value such as XYZ tristimulus values obtained by reading the γ correction chart, and the type of fixing device mounted at the time of output of the γ correction chart (normal fixing device: 0, special fixing device) 1) including “type of fixing device”. In the paper category storage area A13, for example, NO. 1-NO. Ten paper categories can be registered. The characteristics of the color sensor 22 can be corrected by generating a density conversion table or function indicating the relationship between the voltage value output from the color sensor 22 and the density value such as the XYZ tristimulus values based on the paper category.
The non-volatile memory 1b stores default sensor correction data (referred to as a default correction value), and the default correction value can also be used when performing printer γ correction.

  The paper category and default correction value are associated (linked) with the tray paper settings of each paper feed tray. At the time of output paper density adjustment, data for γ correction is generated using the paper category or default correction value associated with the tray paper setting of the paper feed tray on which the target paper for output paper density adjustment is set.

  The association of the paper category or default correction value to the tray paper setting of each paper feed tray can be performed, for example, from the individual setting screen G1 of each tray shown in FIG. Specifically, when an individual setting screen G1 for a desired tray is displayed on the LCD 2a of the operation display unit 2 and the “output paper density adjustment” button is pressed, a “default correction value” button and a “paper category” are displayed in the right area of the screen. "Button and" OFF "button are displayed. When the “default correction value” button is pressed, the default correction value is associated with the paper set in the target tray. When the “paper category” button is pressed, a list screen G2 of registered paper categories is displayed as shown in FIG. 10, and the paper category selected from the list is set in the target tray. Associated with When the “OFF” button is pressed, γ correction by the IDC sensor method is associated.

When the paper category list screen G2 is displayed, the control unit 1a performs the list display control process shown in FIG.
First, it is determined whether or not the type of the fixing device 19 currently installed matches the “fixing device type” of the paper category stored in the paper category storage area A13 (step S1). Here, the type of the fixing device mounted is acquired from the printer control unit 4b based on the fixing device identification signal from the port 10a when the power is turned on, and is stored in the internal memory of the control unit 1a.
If it is determined that the type of the fixing device 19 currently installed matches the “fixing device type” of the paper category (step S1; YES), the “name” or “set date” (update date) of the paper category ) And the like are displayed on the paper category list screen G2 (step S2). If it is determined that the type of the currently installed fixing device 19 and the “fixing device type” of the paper category do not match (step S1; NO), the information on the paper category is not displayed in the list or is shaded. (Step S3). When the processes in steps S1 to S3 for all the paper categories stored in the paper category storage area A13 are completed (step 4; YES), the list display control process is ended.
For example, in FIG. 10, the paper category with registration number 3 corresponds to a fixing device different from the currently installed fixing device, and thus cannot be selected. In this way, the list display control process makes it impossible to select a paper category that does not match the currently installed fuser type, so a paper category that does not match the currently installed fuser type is associated with the paper feed tray. Can be prevented.

  Here, the nonvolatile memory 1b has a tray sheet profile storage area A14 for storing a tray sheet profile. The tray paper profile is setting information about paper set in each paper feed tray of the paper feed unit 12 of the image forming apparatus 10. FIG. 12 shows an example of the data structure of the tray paper profile. By setting the content corresponding to the pressed button of the “printer γ correction mode” of the tray paper profile corresponding to the tray number of the target tray stored in the tray paper profile storage area A14, The printer γ correction method corresponding to the pressed button is associated. When the printer correction mode is set to “2”, the link to the selected paper category is set by setting the registration number of the paper category selected from the list in “Link to Paper Category Database”. The attachment is done.

[Output paper density adjustment settings]
In order to adjust the output paper density, it is necessary to enable the output paper density adjustment in advance on the output paper density adjustment setting screen G3.
FIG. 13 shows an example of the output paper density adjustment setting screen G3. The output paper density adjustment setting screen G3 is a screen for performing various settings for output paper density adjustment. The output paper density adjustment setting screen G3 is displayed according to a predetermined operation from the operation display unit 2.
As shown in FIG. 13, the output paper density adjustment setting screen G3 includes “use of output paper density adjustment”, “adjustment strength”, “automatic adjustment”, “adjustment interval”, and “cooperation with image stabilization control”. An operation button for setting each item is provided.

  The “output paper density adjustment” item is an item for setting whether or not output paper density adjustment is used. When the “Yes” button is pressed, the output paper density adjustment is set to be usable. When the “No” button is pressed, output paper density adjustment is disabled. In this case, all the printer γ correction is performed by the IDC sensor method. By default, “No” is set. When the “Use output paper density adjustment” item is “No”, the following items are shaded and cannot be set.

The “automatic adjustment” item is an item for setting whether or not the output paper density adjustment is automatically executed. When the “ON” button is pressed, the output paper density adjustment is automatically executed at the interval set in “Adjustment interval”. When the “OFF” button is pressed, automatic execution is not performed, but manual adjustment is possible even when the button is OFF. When the “automatic adjustment” item is “OFF”, the following items are shaded and cannot be set.
The “adjustment interval” item is an item for setting the timing of automatic correction. When printing is performed more than the reference number set in this item, output paper density adjustment is automatically executed. By pressing the “change” button, an adjustment interval (reference number) can be set between 100 and 99999 sheets.
The “adjustment strength” item is an item for setting the weighting of γ correction by adjusting the output paper density. The adjustment strength can be set between 1 and 10.
The item “Cooperation with Image Stabilization Control” is an item for setting whether or not output paper density adjustment is automatically executed in response to image stabilization control. When the “Yes” button is pressed, output paper density adjustment linked to image stabilization control is automatically executed. When the “No” button is pressed, the output paper density adjustment linked to the image stabilization control is not performed.

  The setting information set from the output paper density adjustment setting screen G3 is stored in the setting information storage area A11 of the nonvolatile memory 1b. FIG. 14 shows the data structure of the setting information stored in the setting information storage area A11.

[Image stabilization control and output paper density adjustment]
Here, the relationship between image stabilization control and output paper density adjustment will be described.
The image stabilization control is control for stably supplying image quality against changes in environmental factors such as temperature and humidity in the image forming apparatus 10 or replacement of the developer. The main timing when image stabilization control is entered is as follows.
-When the idling state has continued for 6 hours or more-When a predetermined number of sheets have been printed since the previous execution of image stabilization control-When the temperature and humidity in the machine have changed by 20% or more since the previous execution of image stabilization control with the power turned on・ When the developer is replaced

In the image stabilization control, for example, maximum density adjustment, surface potential uniformity correction of the photoreceptor, and halftone density correction are performed. In the maximum density adjustment, the development DC bias is adjusted. In the surface potential uniformity correction, the grid voltage is adjusted. In halftone density correction, the maximum laser power is adjusted. Adjustment of these process conditions electrically corrects a hardware change factor. Therefore, after image stabilization control, it is necessary to regenerate γ correction data that conforms to the process conditions after adjustment.
Therefore, after image stabilization control is performed under the control of the control unit 1a, γ correction data for the IDC sensor method is generated, and γ data is generated using the generated γ correction data. It is stored in the internal memory 1a. The γ data is correction data (γ correction table or function) for canceling the difference between the measured value of the γ correction data and the density value of the correction chart itself.

  However, in order to generate color sensor type γ correction data, that is, to perform output paper density adjustment, it is necessary that the paper for output paper density adjustment be set in any of the paper feed trays of the paper feed unit 12. is there. However, there is a problem that the target paper is not necessarily set in any of the paper feed trays at the end of the image stabilization control. In addition, when image stabilization control is performed during a job, a γ correction chart may be mixed in the printed matter of the job, which may cause an error or missing pages, or cause a decrease in productivity. . Therefore, in the color sensor method, it is not preferable to adjust the output paper density at the end of the image stabilization control as in the IDC sensor method.

  Therefore, in the image forming apparatus 10, the registration state of the registered γ correction data is set to the “readjustment mode” after the image stabilization control under the control of the control unit 1 a. Along with the printing by the job, the printer γ automatic generation process described below is executed, and the registration state of the γ correction data corresponding to the fixing device type, the paper type, and the screen used for printing in the job is “readjustment”. In the case of “mode”, the data for γ correction suitable for the process condition after the image stabilization control is generated by regenerating the data for γ correction.

[Printer γ automatic generation processing]
FIGS. 15 a to 15 b show a flowchart of the printer γ automatic generation process executed by the control unit 1 a of the control board 1. This process is executed in cooperation with the program stored in the control unit 1a and the nonvolatile memory 1b every time a print instruction is issued for each sheet by the job.

  When a paper feed tray (paper feed tray on which paper used for printing is set) is determined based on the job (step S21), the paper is stored in the setting information storage area A11 of the nonvolatile memory 1b. The output paper density adjustment setting information is referred to, and it is determined whether or not the output paper density adjustment is automatically set (step S22). If it is determined that the setting for automatically executing the output paper density adjustment is not made (step S22: NO), this process ends, and the process proceeds to paper feeding for printing by job.

  As a result of the determination, if it is determined that the setting for automatically adjusting the output paper density is made (step S22; YES), it is used at the time of printing stored in the tray paper profile storage area A13 of the nonvolatile memory 1b. The tray paper profile of the paper feed tray is referred to, and it is determined whether or not the set paper is set to perform output paper density adjustment (step S23). Specifically, when the printer γ correction mode of the tray paper profile of the paper feed tray used at the time of printing is “1: default correction value” or “2: paper category”, the set paper is output paper. It is determined that the density adjustment is set.

  If it is determined that the output paper density adjustment is not set in the tray paper profile of the paper feed tray used at the time of printing (step S23; NO), this process ends, and the process proceeds to paper feed for printing by job. To do. If it is determined that the output paper density adjustment is set in the tray paper profile of the paper feed tray used at the time of printing (step S23; YES), it is stored in the γ correction data storage area A12 of the nonvolatile memory 1b. Whether the registration state of the γ correction data for the combination of the paper type used for printing and the screen is “registration” or “readjustment mode” is determined (step S24). If it is determined that the registration state of the γ correction data for the combination of paper type and screen used for printing is “registration” or “readjustment mode” (step S24; YES), the process proceeds to step S25. The registration state of the γ correction data for the combination of paper type and screen used for printing is not “registration” or “readjustment mode”, that is, the γ correction data for the combination of paper type and screen used for printing is “ If it is determined that it is “unregistered” (step S24; NO), the process proceeds to step S30.

  In step S25, the “adjustment point count value” of the γ correction data of the combination of the paper type and screen used for printing stored in the γ correction data storage area A12 of the nonvolatile memory 1b is referred to (step S25). ) Based on the “adjustment point count value” and the total counter value, it is determined whether or not printing has been performed more than a preset reference number after adjusting the output paper density (step S26). Specifically, if the difference obtained by subtracting the “adjustment point count value” of the γ correction data from the total counter value is equal to or greater than the reference number of adjustment interval settings, it is set in advance after adjusting the output paper density. It is determined that more than the reference number of sheets has been printed.

If it is determined that the printing has been performed more than the preset reference number after adjusting the output paper density (step S26; YES), the process proceeds to step S29.
If it is determined that the preset number of sheets has not been printed yet after the output paper density adjustment (step S26; NO), the output paper density adjustment setting information in the nonvolatile memory 1b is referred to, and the image It is determined whether or not it is set to execute the output paper density adjustment in cooperation with the stabilization control (step S27). If it is determined that it is not set to execute the output paper density adjustment in cooperation with the image stabilization control (step S27; NO), this process ends, and the process shifts to printing by job.

  When it is determined that the output paper density adjustment is set in cooperation with the image stabilization control (step S27; YES), the printing stored in the γ correction data storage area A12 of the nonvolatile memory 1b is performed. It is determined whether or not the registration state of the γ correction data for the combination of paper type and screen to be used is “readjustment mode” and if it is not “readjustment mode” (step S28; NO). This process ends, and the process proceeds to paper feeding by job. If it is determined that the registration state of the γ correction data for the combination of paper type and screen used for printing is “readjustment mode” (step S28; YES), the process proceeds to step S29.

  In step S29, the fixing device in which the “fixing device type” of the γ correction data of the combination of the paper type used for printing and the screen stored in the γ correction data storage area A12 of the nonvolatile memory 1b is mounted. It is determined whether or not the type matches (step S29). The type of the fixing device mounted is determined with reference to the internal memory of the control unit 1a. If it is determined that the “fixer type” of the γ correction data for the combination of the paper type used for printing and the screen does not match the type of the installed fixing unit (step S29; NO), this process is performed. The process ends, and the process proceeds to paper feeding for the job.

  On the other hand, if it is determined that the “fixer type” of the γ correction data for the combination of the paper type used for printing and the screen matches the type of the installed fixing unit (step S29; YES), the processing Moves to step S30.

  In step S30, output paper density adjustment is executed (step S30). In the output paper density adjustment, first, paper is fed from a paper feed tray used for printing, and the printing unit 4 prints a γ correction chart on the paper. Next, the γ correction chart printed on the paper is measured by the color sensor 22 to obtain a voltage value as a color measurement result. Next, the voltage value is converted into a density value using a paper category (default correction value in the case of a default correction value) linked in the tray paper profile of the paper feed tray used for the current printing. This generates a sensor measurement. Then, the γ correction data of the combination of the paper type used for printing and the screen is updated based on the generated sensor measurement value and related information (“paper category”, “paper type”, “ "Screen", "Updated date", "Sensor measured value", and "Past sensor measured value" items are updated).

When the output paper density adjustment is completed, the registration state of the γ correction data for the combination of the paper type used for printing and the screen is changed to “registration” (step S31). Further, the type of the currently installed fixing device (0: normal fixing device, 1: special fixing device) stored in the internal memory is set in the “fixing device type” of the γ correction data (step). S32). Further, the count value in the total counter storage area A10 is incremented by 1 (step S33), and the count value of the total counter is copied to the “adjustment point count value” of the γ correction data (step S34).
In other words, in the γ correction data storage area A12 of the nonvolatile memory 1b, the “sensor measurement value” that is an adjustment value obtained by adjusting the output paper density and the count value of the number of printed sheets at the time when the adjustment value is generated. A certain “adjustment time point count value” and a “fixer type” that is identification information of the type of the fixer used to generate the adjustment value are stored in association with each other.

Then, γ data is generated using the updated γ correction data (step S35), and this process ends. In step S35, for example, the density value of the “sensor measurement value” of the γ correction data and the density value data of the correction chart itself are compared, and γ data for canceling the difference is generated. The generated γ data is stored in the internal memory of the control unit 1a in association with the γ correction data (for example, the identification number of the γ correction data) used for generation.
After the end of this process, the control of the control unit 1a starts paper feeding for printing based on the job, and γ corresponding to the type of paper used for printing (and the type of screen) and the type of fixing device. Printer γ correction is performed on the image data to be printed using γ data generated based on the correction data, and printing is performed on the paper by the printing unit 4 based on the corrected image data. If NO is determined in steps S22, S23, and S29, printer γ correction is performed on the image data to be printed using γ data for the IDC sensor method.

  Even when the automatic adjustment of the output paper density adjustment is OFF or the linkage with the image stabilization control is OFF, the γ correction data that matches the process conditions after the adjustment by the manual adjustment is obtained. Can be regenerated. For example, the user operates the operation display unit 2 to display the output paper density adjustment screen G4 shown in FIG. 16 on the LCD 2a, and selects desired γ correction data from the γ correction data displayed on the screen G4. As a result, the output paper density can be adjusted to generate γ correction data that matches the current process conditions. When the γ correction data is displayed as a list on the output paper density adjustment screen G4, the control unit 1a performs the same control as the list display control process described above, and the fixing device in which the “fixing device type” is currently mounted. Is displayed in a list, and γ correction data whose “fixer type” does not match the currently installed fixing device is not displayed in the list or is displayed in a shaded manner. As a result, it is possible to prevent the output paper density from being erroneously adjusted to γ correction data whose “fixer type” is different from that of the currently installed fixing device.

[Printer γ generation processing]
In the above printer γ automatic generation processing, when the timing when output paper density adjustment is necessary at the time of printing has come, or when image stabilization control has been performed and process conditions have changed, the output paper density automatically Adjustment is performed to generate new γ correction data, γ data is generated based on the γ correction data, and γ correction is applied to the image data to be printed using the generated γ data. In other printing operations, γ correction is performed using γ data generated when the power is turned on.

  FIG. 17 shows a flowchart of the printer γ generation process executed when the power is turned on. The printer γ generation process is a process for generating γ data for correcting the printer γ based on γ correction data obtained by output paper density adjustment, and is stored in the control unit 1a and the nonvolatile memory 1b. It is executed in cooperation with the program.

First, information on the type of the fixing device 19 currently installed is acquired via the printer control unit 4b (step S41).
Next, the obtained fixing device type (0: normal fixing device, 1: special fixing device) is stored in the internal memory of the control unit 1a (step S42).

  Next, based on the fixing device type stored in the internal memory, it is determined whether or not the currently mounted fixing device 19 is the normal fixing device 191 (step S43). If it is determined that the currently installed fixing device 19 is the normal fixing device 191 (step 43; YES), among the γ correction data stored in the γ correction data storage area A12 of the nonvolatile memory 1b, Γ correction data with “Fixer type” of “0: Normal fixing device” is acquired, and γ data is generated and stored in the internal memory using the “sensor measurement value” of the acquired γ correction data. (Step S44), the printer γ generation process ends. The generated γ data is stored in the internal memory of the control unit 1a in association with the γ correction data (for example, the identification number of the γ correction data) used for generation.

  On the other hand, if it is determined that the currently installed fixing device 19 is not the normal fixing device 191 (the special fixing device 192) (step 43; NO), it is stored in the γ correction data storage area A12 of the nonvolatile memory 1b. Among the γ correction data that has been acquired, γ correction data having “1: fixing device type” of “1: special fixing device” is acquired, and γ is obtained using the “sensor measurement value” of the acquired γ correction data. Data is generated and stored in the internal memory (step S45), and the printer γ generation process ends. The generated γ data is stored in the internal memory of the control unit 1a in association with the γ correction data (for example, the identification number of the γ correction data) used for generation.

By the printer γ generation process, γ data for correcting the printer γ including the characteristics of the mounted fixing device is stored in the internal memory of the control unit 1a.
When the power is turned on, in addition to the printer γ generation process based on the output paper density adjustment, a process of generating γ data using the data for γ correction by the IDC sensor 17a stored in the nonvolatile memory 1b and storing it in the internal memory Is done.

[Exchange mode processing]
In the image forming apparatus 10, the units of the developing units and the fixing unit 19 of the image forming units 13 to 16 are replaced. At the time of unit replacement, a replacement mode process described later is executed, so that time or The timing for adjusting the density of the output paper that consumes the paper can be optimized.
Here, since replacement of the developer unit affects transfer characteristics, generation (readjustment) of γ correction data after unit replacement is indispensable for both the IDC sensor system and the color sensor system. Further, since the developing device includes a humidity-dependent member such as a developer (toner or carrier), it deteriorates with time in a short period of time, and the transfer characteristics change even if it is kept unused. For this reason, even when the removed developer is remounted and reused, the γ correction data cannot be reused, and must be readjusted every time it is replaced.
On the other hand, since the unit replacement of the fixing device affects only the fixing characteristics, the IDC sensor method can use the γ correction data as it is, but the color sensor method is changed to the γ correction data corresponding to the fixing characteristics. There is a need to. However, when the fixing device is stored without being used, there is almost no change in characteristics due to deterioration over time. Therefore, when the fixing device 19 once removed is remounted and reused according to the use, it is not necessary to adjust the output paper density every time the fixing device 19 is replaced and to regenerate the γ correction data. It is sufficient to adjust the output paper density when the set reference number or more are printed. If the output paper density adjustment is performed every time the fixing device 19 is replaced as in the conventional case, useless time and paper are consumed. Will end up.
Therefore, the image forming apparatus 10 optimizes the adjustment timing of output paper density adjustment by performing the following exchange mode process.

  FIG. 18 shows a flowchart of the exchange mode process. The exchange mode process is executed by the cooperation of the control unit 1a and the program stored in the nonvolatile memory 1b when the operation display unit 2 instructs to switch to the exchange mode.

  First, a list of replaceable units is displayed on the LCD 2a of the operation display unit 2, and a replacement target unit is selected (step S51). Information on the selected unit is temporarily stored in the internal memory.

  Next, it is determined whether or not the fixing device 19 has been selected as a unit to be replaced. If it is determined that the fixing device 19 has been selected (step S52; YES), the data is stored in the γ correction data storage area A12. The color sensor data for γ correction is saved (stored) in the γ correction data saving area A15 (step S53), and the process proceeds to step S54. If it is determined that a device other than the fixing device 19 (here, the developing device) has been selected (step S52; NO), the process proceeds to step S54.

  In step S54, a guide for removing and installing the selected unit is displayed on the LCD 2a of the operation display unit 2 (step S54). When the unit is replaced according to the guide and the mounting is completed (step S55), it is determined whether or not the replaced unit is the fixing device 19 (step S56).

  When it is determined that the replaced unit is the fixing device 19 (step S56; YES), the color sensor γ correction data saved in the γ correction data saving area A15 is the γ correction data storage area A12. (Step S57). Then, by executing the printer γ generation process shown in FIG. 17, γ data is generated using the γ correction data corresponding to the type of the fixing device after replacement (step S58), and the replacement mode process ends. The generated γ data is stored in the internal memory of the control unit 1a in association with the γ correction data (for example, the identification number of the γ correction data) used for generation.

  On the other hand, if it is determined that the replaced unit is not the fixing device 19 (step S56; NO), image stabilization control is executed (step S59). Then, readjustment by the IDC sensor method is performed (step S60). That is, a γ correction chart is formed on the intermediate transfer belt 17, and the γ correction data is generated by the IDC sensor 17a by measuring the color of the γ correction chart, and the generated γ correction data is included in the generated γ correction data. Based on this, γ data is generated and stored in the internal memory. Further, the registration state of the γ correction data stored in the γ correction data storage area A12 and whose registration state is “registration” is changed to “readjustment” (step S61), and the exchange mode process ends. By changing the registration state of the γ correction data stored in the γ correction data storage area A12 and having the registration state “registration” to “readjustment”, a unit that is not the fixing device 19 (here, the development) When the γ correction data is used for the first time after the replacement, the output paper density is always adjusted in the printer γ automatic adjustment process shown in FIGS. 15a to 15b. The data can be changed to γ correction data according to the characteristics.

In the exchange mode process, when the fixing device 19 is exchanged, the γ correction data stored in the γ correction data storage area A12 of the non-volatile memory 1b is stored in association with the type of the fixing device attached by the exchange. The “sensor measurement value” of the data is acquired, and γ data is generated using the acquired “sensor measurement value” and stored in the internal memory. In the printer γ automatic adjustment processing shown in FIGS. 15A to 15B executed at the time of printing, the generated γ is used until the predetermined reference number is reached from the time when the “sensor measurement value” to be used is generated. Printer γ correction is performed using the data.
On the other hand, when a unit other than the fixing unit 19 (here, the developing unit) is exchanged, in the exchange mode process, the γ stored in the γ correction data storage area A12 and whose registration state is “registered”. Since the registration state of the correction data is changed to “readjustment mode”, in the printer γ automatic adjustment process shown in FIGS. 15A to 15B, the output paper density is always set before printing using the first used paper after unit replacement. Adjustment is performed. That is, the output paper density adjustment is executed every time the unit is replaced, and new γ correction data is generated taking into account the characteristics of the installed developing device.

  For example, the reference sheet number of the adjustment interval of output paper density adjustment is 1000 sheets, and fixing is performed when printing 200 sheets from the output paper density adjustment time (gamma correction data generation time) for certain γ correction data. In the conventional image forming apparatus, when the normal fixing device 191 is remounted next time, the γ correction is still performed when the device 19 is replaced (for example, when the normal fixing device 191 is replaced with the special fixing device 192). If the number of printed sheets from the output paper density adjustment point at which the use data is generated does not reach 1000, the output paper density adjustment is performed even though the γ correction data can be used. On the other hand, in the image forming apparatus 10 of the present embodiment, the “γ correction data“ stored in the nonvolatile memory 1b before the replacement until the number of printed sheets from the previous output paper adjustment time reaches 1000 sheets “ Γ data is generated using the “sensor measurement value”, and printer γ correction is performed using the γ data during printing. Therefore, it is possible to optimize the timing of output paper density adjustment and prevent time, paper waste, and reduction in productivity due to output paper density adjustment being performed at an unnecessary timing.

As described above, according to the image forming apparatus 10, when the unit is replaced, the control unit 1a adjusts the adjustment value (sensor correction value) and the adjustment value corresponding to the identification information of the unit attached by the replacement. The data for γ correction including the count value of the total counter at the time of generation is acquired from the nonvolatile memory 1b, and the number of printed sheets from the generation time of the adjustment value calculated based on the count value of the total counter and the acquired count value is Control is performed to correct the characteristics of the print unit 4 using the acquired adjustment value until the predetermined reference number is reached.
Specifically, the unit is a first unit (for example, the fixing device 19) that has almost no change in characteristics over time when not in use, and the control unit 1a is not in use. When a second unit (for example, a developing device) whose characteristics change over time is replaced, the output paper density is adjusted again to generate a new adjustment value, and the generated adjustment value is used. Then, control is performed to correct the characteristics of the print unit 4.
Therefore, it is possible to optimize the timing of output paper density adjustment and prevent time, paper waste, and reduction in productivity due to output paper density adjustment being performed at an unnecessary timing.

  Note that the description in the above embodiment shows a preferred example of the image forming apparatus according to the present invention, and the present invention is not limited to this.

  For example, in the above embodiment, as the best mode, after the stabilization control, the registration state of the γ correction data is set to the “readjustment mode”, and at the time of printing, for γ correction corresponding to the paper type and screen used for printing. Although it has been described that the output paper density adjustment is performed to generate γ correction data when the data registration state is “readjustment mode”, following the stabilization control, The γ correction data corresponding to the type may be updated to generate γ data.

  In the above embodiment, the case where the normal fixing device and the special fixing device (envelope fixing device) are exchanged has been described as an example. However, the present invention is not limited to this. For example, the present invention can also be applied to an image forming apparatus in which the fixing device can be replaced according to the size of the paper.

  In the above embodiment, the γ correction data is saved in the nonvolatile memory 1b of the main body 11 when the unit is replaced. However, a dedicated nonvolatile memory or the like is used for each of the normal fixing device 191 and the special fixing device 192. The γ correction data generated is saved in the storage means of the fixing device 19 used when the γ correction data is generated (that is, when the γ correction chart is generated). Also good. The storage means dedicated to each fixing device 19 may be an RFID (Radio Frequency Identification) tag or the like provided in each fixing device 19, or may be an area dedicated to the nonvolatile memory 1 b of the main body 11. May be. In the case of the RFID tag, an RFID reader is provided in the vicinity of the mounting position of the fixing unit 19 of the printing unit 4.

  In the above embodiment, the first unit is described as a fixing unit and the second unit is a developing unit. However, the present invention is not limited to this. The first unit is a unit related to the process from the transfer to the fixing of the print unit 4 and can be applied to any unit that has almost no change in characteristics over time when not in use. The unit 2 is a unit related to the transfer process of the print unit 4 and can be applied as long as it is a unit that changes its characteristics over time even when it is not used.

  In the above description, an example in which a ROM, a nonvolatile memory, a hard disk, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of each device can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Main body part 12 Paper feed parts 13-16 Photosensitive drum 17 Intermediate transfer belt 18 Transfer roller 19 Fixing device 191 Normal fixing device 192 Special fixing device 21 Relay unit 22 Color sensor 1 Control board 1a Control unit 1b Non-volatile memory 1c Reading processing unit 1d Compression IC
1e DRAM control IC
1f Image memory 1g Expansion IC
1h Write processing unit
2 Operation display unit 2a LCD
2b Operation display control unit 3 Scanner unit 3a CCD
3b Scanner control unit 4 Print unit 4a Printer engine 4b Printer control unit 5 Printer controller 5a Controller control CPU
5b LAN IF
5c USB port 5d DRAM control IC
5e Image memory

Claims (3)

The first unit that has almost no change in characteristics over time when not in use and the second unit that has changes in characteristics over time even when not in use can be attached and detached. An image forming apparatus including a configured printing unit,
A counter for counting the number of printed sheets in the printing means;
An adjusting unit that generates an adjustment value by performing output paper density adjustment for correcting process characteristics from transfer to fixing in the printing unit and characteristics of a sheet used in the printing unit ;
The adjustment value generated by the adjustment means, the count value of the counter when the adjustment value is generated, and the identification information of the first unit used for generating the adjustment value are stored in association with each other. Storage means for
When the first unit is replaced , the adjustment value and the count value corresponding to the identification information of the first unit mounted by the replacement are acquired from the storage unit, and the counter count value and the acquired value are acquired. Until the number of prints from the generation point of the adjustment value calculated based on the count value reaches a predetermined reference number, the characteristics of the printing unit are corrected using the acquired adjustment value,
Control means for generating a new adjustment value by the adjustment means when the second unit is replaced, and correcting the characteristics of the printing means using the generated adjustment value ;
An image forming apparatus comprising: The first unit, the image forming apparatus according to claim 1, wherein the fixing device. The second unit, the image forming apparatus according to claim 1 or 2 is a developing device.

Images