JP5523384B2 - Image forming apparatus and toner density control method - Google Patents

Description

  The present invention relates to an image forming apparatus and a toner density control method.

  In an electrophotographic image forming apparatus such as a multifunction machine or printer, an electrostatic latent image is formed on a photosensitive drum by an exposure device, and toner supplied from a toner container to a developing device is exposed to a developing roller or a developing sleeve. The toner is developed on the body drum.

  In such an image forming apparatus, a sensor is provided in the developing device so that the toner in the developing device does not run out. When a decrease in the toner amount in the developing device is detected by the sensor, the toner is transferred from the toner container to the developing device. Is supplied. As a result, a sufficient amount of toner is continuously held in the developing unit, the toner supply from the developing unit to the photosensitive drum becomes constant, and fluctuations in toner image density are reduced.

  On the other hand, a certain image forming apparatus is provided with a density sensor that detects a developer density in a developing device, a developer density on a developing roller, a toner image density on a transfer belt to which a toner image is transferred from a photosensitive drum, and the like. In accordance with the output of the density sensor, the toner image density is controlled by controlling the output of the exposure apparatus, the developing bias, and the like (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2002-62696

  However, if the concentration sensor is provided as described above, the manufacturing cost of the device increases. In particular, it is not preferable that the manufacturing cost is high for a low-priced device.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and a toner density control method that appropriately control toner image density without using a density sensor.

  In order to solve the above problems, the present invention is configured as follows.

  An image forming apparatus according to the present invention includes a storage device that stores calibration data indicating a correspondence relationship between a plurality of image density setting values and a dot count value at a predetermined toner consumption amount, and a density adjustment record that records density adjustment by a user. And an estimated value of the toner image density from a dot count value counted during a period in which the toner is consumed by a predetermined toner consumption based on the calibration data, and based on the density adjustment recorded by the density adjustment recording unit An image density setting unit that identifies the density adjustment tendency of the user and determines and updates the image density setting value based on the derived estimated value according to the density adjustment tendency.

  As a result, the toner image density is estimated from the dot count value during that period when the toner is consumed by a predetermined amount of toner using calibration data obtained in advance by experiment or the like, so that the toner can be used without using the density sensor. Image density is controlled appropriately. Also, an appropriate image density setting value corresponding to the user's density adjustment tendency is set.

Then, when the estimated value is larger than the pre-updated image density setting value and the density adjustment tendency is an increase in density , the image density setting unit determines the image density setting value based on the derived estimated value, and If the estimated value is larger than the image density setting value and the density adjustment tendency is other than density increase, the image density setting value is left as it is without changing the image density setting value.

  Thereby, the change of the image density setting value in the direction opposite to the user's density adjustment tendency is prohibited, and an appropriate image density setting value according to the user's density adjustment tendency is set.

An image forming apparatus according to the present invention includes a storage device that stores calibration data indicating a correspondence relationship between a plurality of image density setting values and a dot count value at a predetermined toner consumption amount, and a density adjustment record that records density adjustment by a user. And an estimated value of the toner image density from a dot count value counted during a period in which the toner is consumed by a predetermined toner consumption based on the calibration data, and based on the density adjustment recorded by the density adjustment recording unit An image density setting unit that identifies the density adjustment tendency of the user and determines and updates the image density setting value based on the derived estimated value according to the density adjustment tendency. Then, the image density setting unit determines the image density setting value based on the derived estimated value when the estimated value is smaller than the image density setting value before the update and the density adjustment tendency is density reduction, and the update is performed. If the estimated value is smaller than the previous image density setting value and the density adjustment tendency is other than density reduction, the image density setting value is left as it is without changing the image density setting value.

  Thereby, the change of the image density setting value in the direction opposite to the user's density adjustment tendency is prohibited, and an appropriate image density setting value according to the user's density adjustment tendency is set.

An image forming apparatus according to the present invention includes a storage device that stores calibration data indicating a correspondence relationship between a plurality of image density setting values and a dot count value at a predetermined toner consumption amount, and a density adjustment record that records density adjustment by a user. And an estimated value of the toner image density from a dot count value counted during a period in which the toner is consumed by a predetermined toner consumption based on the calibration data, and based on the density adjustment recorded by the density adjustment recording unit An image density setting unit that identifies the density adjustment tendency of the user and determines and updates the image density setting value based on the derived estimated value according to the density adjustment tendency. Then, the image density setting unit specifies the density adjustment tendency as one of density increase, no tendency, and density decrease, the estimated value is larger than the image density setting value before update, and the density adjustment tendency is density increase. In the case where the estimated value is smaller than the image density setting value before the update and the density adjustment tendency is a decrease in density, the image density setting value is determined based on the derived estimated value, and the image density setting before the update is determined. If the estimated value is larger than the value and the density adjustment trend is other than density increase, the estimated value is smaller than the pre-update image density setting value and the density adjustment trend is other than density decrease, and the density adjustment trend is trending If it is none, the image density setting value is left as it is without changing the image density setting value.

  As a result, the change of the image density setting value that contradicts the user's density adjustment tendency is prohibited, and an appropriate image density setting value according to the user's density adjustment tendency is set.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the image density setting unit specifies the density adjustment tendency as density increase when the number of recordings in which the density adjustment by the user is an increase in density is equal to or greater than a predetermined ratio with respect to the total number of recordings.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the image density setting unit identifies the density adjustment tendency as density reduction when the number of recordings in which the density adjustment by the user is density reduction is equal to or greater than a predetermined ratio with respect to the total number of recordings.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the density adjustment recording unit records the density adjustment by the user every time one job is executed.

  The image forming apparatus according to the present invention may be configured as follows in addition to any of the image forming apparatuses described above. In this case, the image density setting unit determines the image density setting value without using a density sensor that measures the toner image density.

The toner density control method according to the present invention is based on calibration data indicating a correspondence relationship between a step of recording density adjustment by a user and a plurality of image density setting values and a dot count value at a predetermined toner consumption amount. A step of deriving an estimated value of toner image density from a dot count value counted during a period in which a predetermined toner consumption amount is consumed, and a user's density adjustment tendency is identified based on the recorded density adjustment, and the density adjustment tendency Accordingly, determining and updating the image density setting value based on the derived estimated value , and when the estimated value is larger than the image density setting value before the update and the density adjustment tendency is density increase, The image density setting value is determined based on the derived estimated value, the estimated value is larger than the image density setting value before update, and the density adjustment tendency is other than density increase Expediently, it left as it is an image density setting values without changing the image density setting. Further, the toner density control method according to the present invention is based on calibration data indicating a correspondence between a step of recording density adjustment by a user and a dot count value at a plurality of image density setting values and a predetermined toner consumption amount. Deriving an estimated value of the toner image density from the dot count value counted during a period in which the toner is consumed by a predetermined amount of toner consumption, and specifying the density adjustment tendency of the user based on the recorded density adjustment, and adjusting the density A step of determining and updating an image density setting value based on the derived estimated value according to the trend, the estimated value being smaller than the image density setting value before the update, and the density adjustment tendency being a density decrease Determines the image density setting value based on the derived estimated value, the estimated value is smaller than the image density setting value before update, and the density adjustment tendency is other than density reduction In some cases, an intact image density setting values without changing the image density setting.

  As a result, the toner image density is estimated from the dot count value during that period when the toner is consumed by a predetermined amount of toner using calibration data obtained in advance by experiment or the like, so that the toner can be used without using the density sensor. Image density is controlled appropriately. Also, an appropriate image density setting value corresponding to the user's density adjustment tendency is set.

  According to the present invention, the toner image density is appropriately controlled without using a density sensor.

FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a side view showing the developing unit in FIG. 1, and the photosensitive drum and toner container around the developing unit. FIG. 3 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of the calibration data shown in FIG. FIG. 5 is a flowchart illustrating toner image density control by the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram showing an example of density adjustment recording data by the density adjustment recording unit in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is an apparatus having an electrophotographic printing function, such as a printer, a facsimile machine, a copying machine, or a multifunction machine.

  The image forming apparatus of this embodiment has a tandem color developing device. The color developing device includes photosensitive drums 1a to 1d, exposure devices 2a to 2d, and developing devices 3a to 3d. The photoconductor drums 1a to 1d are four-color photoconductors of cyan, magenta, yellow, and black. The photosensitive drums 1a to 1d are made of amorphous silicon, for example.

  The exposure devices 2a to 2d are devices that form electrostatic latent images by irradiating the photosensitive drums 1a to 1d with laser light while scanning. The laser beam is scanned in a direction (main scanning direction) perpendicular to the rotation direction (sub-scanning direction) of the photosensitive drums 1a to 1d. The exposure apparatuses 2a to 2d have a laser scanning unit including a laser diode that is a light source of laser light and an optical element (lens, mirror, polygon mirror, etc.) that guides the laser light to the photosensitive drums 1a to 1d.

  Further, around the photosensitive drums 1a to 1d, a charger such as a scorotron, a cleaning device, a static eliminator and the like are arranged. The cleaning device removes residual toner on the photosensitive drums 1a to 1d after the primary transfer, and the static eliminator neutralizes the photosensitive drums 1a to 1d after the primary transfer.

  The developing units 3a to 3d are connected to toner containers filled with toners of four colors of cyan, magenta, yellow and black, respectively, and supply toner supplied from the toner containers to the photosensitive drums 1a to 1d. A toner image is formed by attaching toner to the electrostatic latent images on the photosensitive drums 1a to 1d.

  The photosensitive drum 1a, the exposure device 2a, and the developing unit 3a develop magenta, and the photosensitive drum 1b, the exposure device 2b, and the developing unit 3b develop cyan, the photosensitive drum 1c, and the exposure device 2c. The developing unit 3c performs yellow development, and the photosensitive drum 1d, the exposure device 2d, and the developing unit 3d perform black development.

  FIG. 2 is a side view showing the developing device 3a and the photosensitive drum 1a and the toner container 11a around the developing device 3a in FIG. Although FIG. 2 shows the periphery of the developing device 3a, the periphery of the developing devices 3b to 3d has the same configuration.

  For example, when the developing device 3a is a two-component developing device, as shown in FIG. 2, the developing device 3a includes a developing sleeve 21 and a magnetic permeability sensor 22 for measuring the amount of toner in the developing device 3a. Have. The toner container 11a is connected to the developing device 3a, and when the toner supply roller 31 of the toner container 11a rotates by a predetermined amount, a predetermined amount of toner is supplied from the toner container 11a to the developing device 3a. When a decrease in the toner amount is detected by the magnetic permeability sensor 22, the toner supply roller 31 is driven by a toner supply motor (not shown), and toner is supplied to the developing device 3a.

  The intermediate transfer belt 4 is an annular image carrier (intermediate transfer member) that comes into contact with the photosensitive drums 1a to 1d and primarily transfers the toner images on the photosensitive drums 1a to 1d. The intermediate transfer belt 4 is stretched around a driving roller 5 and circulates in the direction from the contact position with the photosensitive drum 1d to the contact position with the photosensitive drum 1a by the driving force from the driving roller 5. .

  The transfer roller 6 brings the conveyed paper into contact with the intermediate transfer belt 4 and secondarily transfers the toner image on the intermediate transfer belt 4 to the paper. The sheet on which the toner image has been transferred is conveyed to the fixing device 9 and the toner image is fixed on the sheet.

  The roller 7 has a cleaning brush, and the cleaning brush is brought into contact with the intermediate transfer belt 4 to remove the toner remaining on the intermediate transfer belt 4 after the transfer of the toner image onto the paper.

  FIG. 3 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. As illustrated in FIG. 2, the image forming apparatus includes a printing device 41, an image reading device 42, an operation panel 43, a communication device 44, a storage device 45, and an arithmetic processing device 46.

  The printing apparatus 41 is an internal device that prints a document image on paper with a mechanical configuration as shown in FIG.

  The image reading device 42 is an internal device that feeds a document with, for example, an auto document feeder, optically reads an image of the document page by page, and generates image data of each page image.

  The operation panel 43 is arranged on the surface of the casing of the image forming apparatus, and includes a display device that displays various types of information to the user and an input device that detects a user operation. For example, a liquid crystal display is used as the display device. A key switch, a touch panel, or the like is used as the input device.

  For example, the user operates the operation panel 43 when making a copy job execution request. At this time, the user displays an image density adjustment screen on the operation panel 43, and selects a desired density adjustment value from, for example, five levels of density adjustment values from −2 to +2. When a negative value is selected as the density adjustment value, an image having a lower density than the default is formed. When a positive value is selected as the density adjustment value, an image having a higher density than the default is formed, and the density adjustment value is set as the density adjustment value. If zero is selected, a default density image is formed.

  The communication device 44 can be connected to a host device via a network or a peripheral device interface, and performs data communication using a predetermined communication protocol.

  The storage device 45 is a device capable of storing various data and programs. As the storage device 45, a nonvolatile large-capacity storage medium such as a nonvolatile memory or a hard disk drive is used. Calibration data 51 is stored in the storage device 45.

  The calibration data 51 is data indicating a correspondence relationship between a plurality of image density setting values and a dot count value at a predetermined toner consumption amount. In this embodiment, the calibration data 51 includes a plurality of image density setting values (ID setting values, ID: Image Density) and a dot count value at a predetermined toner consumption amount for each toner color to be used. Data indicating the corresponding relationship.

  FIG. 4 is a diagram showing an example of the calibration data 51 shown in FIG. The calibration data 51 shown in FIG. 4 includes five image density setting values at intervals of 0.1 from 1.1 to 1.5, and each image density setting value when 250 mg of toner is consumed by a predetermined toner consumption amount. Dot count value. Further, the calibration data 51 includes information (30 seconds in FIG. 4) of toner supply time (that is, operation time of the above-described toner supply motor) corresponding to the consumption of the predetermined toner consumption of 250 milligrams.

  The calibration data 51 is obtained in advance by, for example, an experiment using an ISO / IEC19752 standard manuscript with an apparatus having an electrophotographic process similar to that of the image forming apparatus.

  The arithmetic processing unit 46 is a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. Various processing units are realized by executing the program by the CPU.

  After the image forming apparatus is activated, various programs are appropriately executed by the arithmetic processing unit 46. In this embodiment, the processing unit 46 implements processing units such as an operating system (not shown), a request processing unit 61, an image processing unit 62, controllers 63 and 64, an image density setting unit 65, and a density adjustment recording unit 66. Is done.

  The request processing unit 61 receives a job execution request (for example, a copy job execution request) based on a user operation on the operation panel 43 or a job execution request (for example, a print job execution request) supplied from the host device, and receives the job request. Execute the job according to. For example, when document data in a predetermined data format such as PDL (Page Description Language) or PDF (Portable Document Format) is received from the host device as a print job execution request, the request processing unit 61 generates an image from the document data. Generate data. This image data is raster image data. When the original image data of the raster image data is received from the host device, the request processing unit 61 directly uses the original data as image data. The image processing unit 62 performs predetermined image processing such as color conversion, gamma correction, and halftoning on the image data, and print data (for example, print image data binarized for each color). Generate. Then, the request processing unit 61 causes the controller 63 to execute printing based on the print data.

  Also, for example, upon receiving a copy job execution request, the request processing unit 61 causes the controller 64 to execute image scanning, and the image processing unit 62 performs predetermined image processing on the image data obtained by the image scanning. To generate print data. Then, the request processing unit 61 causes the controller 63 to execute printing based on the print data.

  The controller 63 is a processing unit that monitors and controls the printing apparatus 41. The controller 63 controls a toner source development, transfer and fixing by controlling a driving source (not shown) for driving the above-described roller, a bias application circuit for applying a development bias and a primary transfer bias, and exposure apparatuses 2a to 2d. And a processing circuit for executing paper feeding, printing, and paper ejection. The developing bias is applied between the photosensitive drums 1a to 1d and the developing devices 3a to 3d (the developing sleeve 21 in FIG. 2), respectively, and the primary transfer bias is the photosensitive drums 1a to 1d and the intermediate transfer belt 4. Between the two.

  Further, the controller 63 determines the development bias voltage value according to the image density setting value determined by the image density setting unit 65.

  Further, the controller 63 has a dot counter for counting the number of dots in the print image by the printing apparatus 41 based on the print data, and the dot count value (cumulative value) is calculated every time a print job or one page is printed. Update.

  Further, the controller 63 controls the toner supply motor (not shown) to operate the toner supply roller 31 when the magnetic permeability sensor 22 detects a decrease in the toner amount in the developer 3a. The toner is supplied from the toner container 11a to the developing device 3a. At this time, the controller 63 specifies the operation time (that is, toner supply time) of the toner supply motor in one toner supply, and updates the accumulated value of the toner supply time each time the toner supply roller 31 is operated. This toner supply time corresponds to the toner supply amount (that is, toner consumption amount) from the toner container 11a to the developing device 3a. The controller 63 similarly specifies the toner supply time for the developing devices 3a to 3d, and calculates the accumulated value.

  The controller 64 is a processing unit that monitors and controls the image reading device 42.

  The density adjustment recording unit 66 is a processing unit that records density adjustment by the user. The density adjustment recording unit 66 identifies the density adjustment value input from the operation panel 43 or the density adjustment value designated by the host device, and sets the number of times each density adjustment value is set (that is, for a job using each density adjustment value). Number) and is stored in the storage device 45 as density adjustment record data. That is, the density adjustment recording unit 66 specifies and records the density adjustment value every time one job is executed.

  The image density setting unit 65 (a) does not use a density sensor that measures the toner image density, but based on the calibration data 51, from the dot count value counted during a period in which the toner is consumed by a predetermined toner consumption amount. An estimated value of the toner image density is derived, (b) a user's density adjustment tendency is specified based on the density adjustment recorded by the density adjustment recording unit 66, and (c) an estimation derived according to the density adjustment tendency. The image density setting value is determined and updated based on the value. In this embodiment, the image density setting unit 65 determines and updates an image density setting value for each color of toner to be used.

  In this embodiment, the image density setting unit 65 specifies that the density adjustment tendency is density increase when the number of recordings in which the density adjustment by the user is an increase in density is equal to or greater than a predetermined ratio with respect to the total number of recordings. Also, the image density setting unit 65 specifies the density adjustment tendency as density reduction when the number of recordings in which the density adjustment by the user is density reduction is equal to or greater than a predetermined ratio with respect to the total number of recordings.

  In this embodiment, when the estimated value is larger than the pre-updated image density setting value and the density adjustment tendency is an increase in density, the image density setting unit 65 sets the image density based on the estimated value. If the estimated value is larger than the pre-updated image density setting value and the density adjustment tendency is other than density increase, leave the image density setting value unchanged without changing the image density setting value. To do.

  In this embodiment, when the estimated value is smaller than the pre-updated image density setting value and the density adjustment tendency is a decrease in density, the image density setting unit 65 determines the image density based on the estimated value. When the set value is determined and the estimated value is smaller than the pre-updated image density setting value and the density adjustment tendency is other than density reduction, the image density setting value is left as it is without changing the image density setting value. To do.

  Further, in this embodiment, the image density setting unit 65 specifies the density adjustment tendency as one of density increase, no tendency, and density decrease, and when the density adjustment tendency is no tendency, the image density setting is performed. The image density setting value is left as it is without changing the value.

  Next, the operation of the image forming apparatus will be described.

  FIG. 5 is a flowchart illustrating toner image density control by the image forming apparatus according to the embodiment of the present invention.

  When the image forming apparatus is activated, the image density setting unit 65 monitors whether or not the cumulative value of the toner supply time measured by the controller 63 has reached the toner supply time specified by the calibration data 51 ( Step S1). Note that the cumulative value of toner supply time and the dot count value are stored in the non-volatile storage device 45 and are continuously counted even when the power of the image forming apparatus is turned on / off.

  When the cumulative value of the toner supply time measured by the controller 63 has reached the toner supply time specified by the calibration data 51, the image density setting unit 65 executes the following processing.

  First, the image density setting unit 65 refers to the calibration data 51 and estimates an actual image density value (hereinafter referred to as an estimated ID value) from the dot count value by the controller 63 at this time (step S2). If the same dot count value as the dot count value by the controller 63 does not exist in the calibration data 51, the estimated ID value is calculated by interpolation or extrapolation.

  For example, when the calibration data 51 is as shown in FIG. 4, if the dot count value is 35 million dots, the estimated ID value is 1.3, and if the dot count value is 42.5 million dots, the estimated ID value is 1 If the dot count value is 50 million dots, the estimated ID value is 1.0.

  Next, the image density setting unit 65 reads out the density adjustment recording data from the density adjustment recording unit 66, and specifies the density adjustment tendency of the user based on the density adjustment recording data (step S3).

  The image density setting unit 65 first calculates the total number of times of recording, and then calculates the number of times of recording (hereinafter referred to as the number of times of increase in density) where the user's density adjustment value is a value that increases the density. The number of times of recording (hereinafter referred to as the number of density reductions) in which the adjustment value is a value that decreases the density is calculated. Then, the image density setting unit 65 calculates the ratio of the density increase count to the total recording count and the ratio of the density decrease count to the total recording count, and whether these ratios are equal to or higher than a predetermined threshold (for example, 50 percent). Respectively.

  Then, the image density setting unit 65 identifies the user's density adjustment tendency as “no tendency” when the ratio of the density increase frequency to the total recording frequency and the ratio of the density decrease frequency to the total recording frequency are not equal to or greater than a predetermined threshold. If the ratio of density increase to the total number of recordings is equal to or greater than a predetermined threshold, the user's density adjustment tendency is specified as density increase, and the ratio of the density decrease to the total number of recordings is equal to or greater than the predetermined threshold. The user's density adjustment tendency is specified as density reduction.

  FIG. 6 is a diagram showing an example of density adjustment recording data by the density adjustment recording unit 66 in FIG. In the density adjustment record data shown in FIG. 6, the number of times the density adjustment values (−2 and −1) for decreasing the density are set to zero, and the number of times the user has not performed density adjustment (that is, the density adjustment value is zero). ) Is 150, the number of times the density adjustment value (+1) for increasing the density by one level is 300, and the number of times set for the density adjustment value (+2) for increasing the density by two levels is 50. is there. When the density adjustment record data is in the state shown in FIG. 6, the total number of times of recording is 500 (= 150 + 300 + 50), the number of times of increasing density is 350 (= 300 + 50), and the number of times of decreasing density is 0 (= 0 + 0). . Therefore, when the above-described threshold is 50%, the user's density adjustment tendency is specified as the density increase.

  Then, the image density setting unit 65 determines whether or not a density adjustment tendency for density increase or density decrease has been detected (step S4). It is determined whether or not the direction of change from the image density setting value to the estimated ID value (that is, density increase or density decrease) matches the specified user density adjustment tendency (step S5). For example, when the current image density setting value is 1.2 and the estimated ID value is 1.3, the change direction from the current image density setting value to the estimated ID value is density increase, and the current image density setting When the value is 1.2 and the estimated ID value is 1.1, the change direction from the current image density setting value to the estimated ID value is a density decrease.

  If they match, the image density setting unit 65 updates the image density setting value with the estimated ID value, and further updates the setting value of the developing bias according to the change in the image density setting value (step S6). Then, the image density setting unit 65 sets the development bias setting value obtained in step S6 in the controller 63 (step S7).

  On the other hand, the image density setting unit 65 does not match both when the density adjustment tendency of density increase or density decrease is not detected in step S4 (that is, when there is no tendency) and in step S5. In this case, the current image density setting value is maintained as it is without performing the processing of step S7 and step S8.

  Then, the image density setting unit 65 resets the cumulative value of toner supply time and the dot count value in the controller 63 to zero, and resets all the recording counts in the density adjustment recording data by the density adjustment recording unit 66 to zero (step S40). S8).

  As described above, when the cumulative value of the toner supply time measured by the controller 63 reaches the toner supply time specified by the calibration data 51, the image density setting unit 65 performs the above-described processing, and then the image density setting unit 65 The process returns to the monitoring (step S1) as to whether or not the cumulative value of the toner supply time measured by (1) has reached the toner supply time specified by the calibration data 51.

  As described above, according to the above-described embodiment, the storage device 45 stores the calibration data 51 indicating the correspondence between the plurality of image density setting values and the dot count value at a predetermined toner consumption amount. Then, based on the calibration data 51, the image density setting unit 65 derives an estimated value of the toner image density from the dot count value counted during the period in which the toner is consumed by the predetermined toner consumption amount, and the derived estimated value The image density setting value is determined and updated based on the above.

  As a result, the toner image density is estimated from the dot count value in the period when the toner is consumed by a predetermined amount of toner using the calibration data 51 obtained in advance by an experiment or the like, without using the density sensor. The toner image density is appropriately controlled.

  Further, according to the above embodiment, the image density setting unit 65 identifies the user's density adjustment tendency based on the density adjustment recorded by the density adjustment recording unit 66 and derives it according to the density adjustment tendency. An image density setting value is determined and updated based on the estimated ID value.

  Thereby, an appropriate image density setting value is set according to the density adjustment tendency of the user.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, the image forming apparatus according to the above embodiment is a color electrophotographic image forming apparatus, but may be a monochrome electrophotographic image forming apparatus.

  In the above embodiment, when the image density setting unit 65 updates the image density setting, the difference between the image density setting value before the update and the estimated ID value is equal to or less than a predetermined fluctuation upper limit value (positive value). If it is present and greater than or equal to a predetermined lower limit of variation (negative value), the estimated ID value is used as the image density setting value. If the difference between the pre-updated image density setting value and the estimated ID value is greater than the variation upper limit value, updating is performed. The value obtained by adding the upper limit of variation to the previous image density setting value is used as the image density setting value. If the difference between the image density setting value before update and its estimated value is smaller than the lower limit of variation, the image density setting value before update A value obtained by adding the variation lower limit value to the image density setting value may be used.

  The present invention is applicable, for example, to toner density control in an image forming apparatus that does not have a density sensor.

45 Storage Device 51 Calibration Data 65 Image Density Setting Unit 66 Density Adjustment Recording Unit

Claims (9)

In an image forming apparatus that adjusts a toner image density based on an image density setting value,
A storage device for storing calibration data indicating a correspondence relationship between a plurality of image density setting values and a dot count value at a predetermined toner consumption amount;
A density adjustment recording section for recording the density adjustment by the user;
Based on the calibration data, an estimated value of toner image density is derived from a dot count value counted during a period in which toner is consumed by the predetermined toner consumption amount, and the density adjustment recorded by the density adjustment recording unit is used for the density adjustment recorded. An image density setting unit that identifies a density adjustment tendency of the user based on the image density setting value and determines and updates the image density setting value based on the estimated value derived according to the density adjustment tendency;
With
The image density setting unit determines the image density setting value based on the derived estimated value when the estimated value is larger than the image density setting value before update and the density adjustment tendency is density increase. If the estimated value is larger than the image density setting value before update and the density adjustment tendency is other than density increase, the image density setting value is left as it is without changing the image density setting value. images forming device you characterized in that a. In an image forming apparatus that adjusts a toner image density based on an image density setting value,
A storage device for storing calibration data indicating a correspondence relationship between a plurality of image density setting values and a dot count value at a predetermined toner consumption amount;
A density adjustment recording section for recording the density adjustment by the user;
Based on the calibration data, an estimated value of toner image density is derived from a dot count value counted during a period in which toner is consumed by the predetermined toner consumption amount, and the density adjustment recorded by the density adjustment recording unit is used for the density adjustment recorded. An image density setting unit that identifies a density adjustment tendency of the user based on the image density setting value and determines and updates the image density setting value based on the estimated value derived according to the density adjustment tendency;
With
The image density setting unit, when the estimated value is smaller than the image density set value before update and the density adjustment tendency is density decrease, calculates the image density set value based on the derived estimated value. When the estimated value is smaller than the image density setting value before update and the density adjustment tendency is other than density reduction, the image density setting value is left as it is without changing the image density setting value. images forming device you characterized in that a. In an image forming apparatus that adjusts a toner image density based on an image density setting value,
A storage device for storing calibration data indicating a correspondence relationship between a plurality of image density setting values and a dot count value at a predetermined toner consumption amount;
A density adjustment recording section for recording the density adjustment by the user;
Based on the calibration data, an estimated value of toner image density is derived from a dot count value counted during a period in which toner is consumed by the predetermined toner consumption amount, and the density adjustment recorded by the density adjustment recording unit is used for the density adjustment recorded. An image density setting unit that identifies a density adjustment tendency of the user based on the image density setting value and determines and updates the image density setting value based on the estimated value derived according to the density adjustment tendency;
With
The image density setting unit specifies the density adjustment tendency as one of density increase, no tendency, and density decrease, the estimated value is larger than the image density setting value before update, and the density adjustment tendency is density If the estimated value is smaller than the image density setting value before update and the density adjustment tendency is a density decrease, the image density setting value is determined based on the derived estimated value. When the estimated value is larger than the image density setting value before update and the density adjustment tendency is other than density increase, the estimated value is smaller than the image density set value before update and the density adjustment tendency image If is is other than concentration decreases, and wherein when the density adjustment tendency is no tendency, you characterized in that the image density set value as it is without changing the image density setting value Forming apparatus. The image density setting unit is characterized by specifying the density adjustment tendency as density increase when the number of recordings in which the density adjustment by the user is an increase in density is a predetermined ratio or more with respect to the total number of recordings. The image forming apparatus according to claim 1 or 3 . The image density setting unit specifies the density adjustment tendency as density reduction when the number of recordings in which density adjustment by the user is density reduction is equal to or greater than a predetermined ratio with respect to the total number of recordings. the image forming apparatus of claim 2 or claim 3, wherein. The density adjustment recording unit, an image forming apparatus according to any one of claims 5 to record the density adjustment by the user for each execution of one job claim 1, wherein. The said image density setting part determines the said image density setting value, without using the density sensor which measures the said toner image density, The any one of Claims 1-6 characterized by the above-mentioned. Image forming apparatus. In a toner density control method for adjusting a toner image density based on an image density setting value,
Recording the density adjustment by the user;
Based on the calibration data indicating the correspondence between the plurality of image density setting values and the dot count value at the predetermined toner consumption amount, the toner image is obtained from the dot count value counted in the period in which the toner is consumed by the predetermined toner consumption amount. Deriving an estimate of the concentration;
Identifying a user's density adjustment tendency based on the recorded density adjustment, and determining and updating the image density setting value based on the derived estimated value according to the density adjustment tendency;
Equipped with a,
When the estimated value is larger than the image density setting value before update and the density adjustment tendency is density increase, the image density setting value is determined based on the derived estimated value, and the image density before update is determined. When the estimated value is larger than the image density setting value and the density adjustment tendency is other than density increase, the image density setting value is left as it is without changing the image density setting value;
A toner density control method. In a toner density control method for adjusting a toner image density based on an image density setting value,
Recording the density adjustment by the user;
Based on the calibration data indicating the correspondence between the plurality of image density setting values and the dot count value at the predetermined toner consumption amount, the toner image is obtained from the dot count value counted in the period in which the toner is consumed by the predetermined toner consumption amount. Deriving an estimate of the concentration;
  Identifying a user's density adjustment tendency based on the recorded density adjustment, and determining and updating the image density setting value based on the derived estimated value according to the density adjustment tendency;
With
When the estimated value is smaller than the image density setting value before update and the density adjustment tendency is density decrease, the image density setting value is determined based on the derived estimated value, and the image density before update is determined. When the estimated value is smaller than the image density setting value and the density adjustment tendency is other than density reduction, the image density setting value is left as it is without changing the image density setting value.
A toner density control method.

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