JP5204696B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a recording medium.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus that forms an image by fixing toner on a predetermined recording medium is known. The image forming apparatus includes a toner image obtained by charging and exposing a photosensitive drum, supplying toner from a toner supply roller to a developing roller, and attaching toner on the developing roller to an electrostatic latent image formed on the photosensitive drum. The image is formed on the recording medium through the processes of forming (developing) the toner, transferring the formed toner image onto the recording medium conveyed by the transfer belt, and fixing the toner image transferred to the recording medium. Is forming.

  In such an image forming apparatus, conventionally, “blurring” and “dirt” caused by aging and environmental changes have been adjusted by correcting the voltage difference between the bias voltages of the developing roller and the toner supply roller. In particular, in a low humidity environment, “dirt” occurs due to excessive charging of the toner more than necessary. Therefore, the voltage difference between the developing roller and the toner supply roller is reduced to limit the amount of toner on the developing roller. Then, the charge on the developing roller is lowered to suppress the occurrence of “dirt” (for example, see Patent Document 1).

  “Dirt” in an electrophotographic image forming apparatus is a phenomenon in which extra toner adheres to a background portion of an image, that is, a non-image portion due to a toner having a large charge amount relative to a normally charged toner, that is, a so-called overcharged toner. An overcharged toner that causes “dirt” is referred to as “dirt toner”.

JP 2004-029681 A

However, for example, in the technique disclosed in Patent Document 1, since the charging of the toner on the developing roller is reduced, “fogging” in which an extra image is printed on the non-image portion on the recording medium may be deteriorated. There's a problem.
Note that “fogging” in an electrophotographic image forming apparatus is caused by excessively charged toner in a background portion of an image, that is, a non-image portion due to a toner having a low charge amount or a toner having a reverse polarity with respect to a normally charged toner. A toner having a low charge amount or a toner charged to a reverse polarity that causes “fogging” is referred to as “fogging toner”.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of suitably suppressing the occurrence of “fogging” and “dirt” without deteriorating “fogging”.

In order to solve the above problems, the present invention provides an image carrier on which an electrostatic latent image is formed by exposure with light emitted from an exposure unit , a developer carrier that adheres a developer to the image carrier, A developer supply body that supplies the developer to the developer carrier, a voltage application unit that applies different bias voltages to the developer carrier and the developer supply body, the image carrier and the image carrier A rotation drive unit that rotates and drives the developer carrier, and a linear speed ratio between the image carrier and the developer carrier, and the image carrier and the developer carrier at the set linear speed ratio. An image forming apparatus comprising: a control unit that controls the rotation driving unit so as to rotate the body, wherein the control unit is applied to the developer carrier and the developer supply body, respectively. The smaller the difference in the bias voltage, the more the developer carrier line Characterized in that setting the linear velocity ratio so as to increase

Incidentally, an image bearing member on which an electrostatic latent image by exposing with light exposure light portion is irradiated is formed, a developer carrying member for attaching the developer to the image carrier, the image carrier and the developer carrier A rotation drive unit that rotates the image carrier, and a linear speed ratio between the image carrier and the developer carrier, and a rotation drive unit that rotationally drives the image carrier and the developer carrier at the set linear speed ratio. An image forming apparatus including a control unit for controlling and an environmental state detection unit for detecting an ambient environmental state, wherein the control unit sets a linear speed ratio based on the environmental state. .

The control unit of the image forming apparatus can set a linear speed ratio between the image carrier on which the electrostatic latent image is formed and the developer carrier on which the developer is attached to the image carrier based on the environmental state.
The control unit can control the rotation driving unit to rotationally drive the image carrier and the developer carrier at the set linear velocity ratio.
According to the present invention, it is possible to increase the rotation speed of the image carrier and to suppress a decrease in the charge amount of the toner, so that deterioration of “fogging” can be suppressed. In addition, since the linear velocity ratio between the image carrier and the developer carrier is set based on the environmental state, the occurrence of “fading” and “dirt” can be suppressed.
Therefore, it is possible to provide an image forming apparatus capable of suitably suppressing the occurrence of “fogging” and “dirt” without deteriorating “fogging”.

1 is a diagram illustrating a configuration example of an image forming apparatus. It is a figure which shows the structural example of an image formation part. 2 is a diagram illustrating a control system of the image forming apparatus. FIG. (A) is a figure which shows an example of | DB-SB | environmental correction table, (b) is a figure which shows an example of a linear velocity table. 5 is a flowchart illustrating a procedure for setting a linear velocity of a developing roller by a print control unit. It is a graph which shows the relationship between | DB-SB | and color difference (DELTA) E in the case of low temperature and low humidity. It is a graph which shows the relationship between | DB-SB | and color difference (DELTA) E in the case of high temperature high humidity. (A) is a figure which shows an example of a time-dependent correction table, (b) is a figure which shows an example of a printing density correction table, (c) is a figure which shows an example of a user correction table. 10 is a flowchart illustrating an operation of the image forming apparatus according to the second embodiment.

<< First Embodiment >>
DESCRIPTION OF EMBODIMENTS Hereinafter, a first embodiment for carrying out the present invention will be described in detail with reference to the drawings as appropriate.
An image forming apparatus 100 according to the first embodiment is a tandem type image forming apparatus 100 capable of forming (printing) a color image on a recording sheet 9 as a recording medium. As shown in FIG. The image forming unit 101 (black image forming unit 101k) for forming a black toner image and the image forming unit 101 (for forming a yellow toner image) from the upstream side with respect to the running direction of the transfer belt 1, for example. A yellow image forming unit 101y), an image forming unit 101 that forms a magenta toner image (magenta image forming unit 101m), and an image forming unit 101 that forms a cyan toner image (cyan image forming unit 101c) are arranged in this order. Has been.
A control unit 102 that controls each unit of the image forming apparatus 100 is provided. The control unit 102 includes a humidity sensor 14 that measures the humidity of the atmosphere and a temperature sensor 15 that measures the atmospheric temperature.

The transfer belt 1 travels, for example, in the left rotation direction in FIG. 1 by drive rollers 110a and 110b that are rotationally driven by a drive source (such as a motor) (not shown), and converts the toner image formed by each image forming unit 101 into a black image. The recording sheet 9 is conveyed downstream while being transferred to the recording sheet 9 in the order of the forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c.
In addition, a density detection pattern for measuring the toner density is transferred to the transfer belt 1, and the toner is formed by a density sensor 91 including a light emitting unit and a light receiving unit (not shown) provided in the image forming apparatus 100. The concentration is measured.

  Further, a fixing device 120 as a fixing unit is disposed downstream of the cyan image forming unit 101c, and fixes the toner transferred to the conveyed recording paper 9.

  In addition, the image forming apparatus 100 collects a cleaning blade 150 that removes excess toner adhering to the transfer belt 1 and cleans the surface, and toner (waste toner) that is removed from the transfer belt 1 by the cleaning blade 150. A transfer belt waste toner box 170 is provided.

Next, the configuration of the image forming unit 101 will be described mainly with reference to FIG.
As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment includes four image forming units, a black image forming unit 101k, a yellow image forming unit 101y, a magenta image forming unit 101m, and a cyan image forming unit 101c. Although the part 101 is arrange | positioned, all are the same structures.

As shown in FIG. 2, the image forming unit 101 includes a photosensitive drum 10 as an image carrier, a charging roller 21, an LED (Light Emitting Diode) head 22 as an exposure unit, and a transfer voltage on a recording sheet 9 (FIG. 1). The transfer roller 51 for applying to the reference is disposed.
The photosensitive drum 10 is, for example, a roller having an outer diameter of 30 mm and a film having a thickness of about 20 μm on the photosensitive surface. The film on the photosensitive surface is negatively charged by the charging roller 21 and then irradiated from the LED head 22. An electrostatic latent image of an image that is exposed to light and transferred to the recording paper 9 is formed.

Further, the image forming unit 101 is provided with a developing unit 2, and the developing unit 2 includes a toner cartridge 140 that stores toner 3 as a developer, a developing roller 41 as a developer carrying member, a layer forming blade 72, and development. It includes a toner supply roller 71 as an agent supply body.
The developing roller 41 is configured by forming a semiconductive elastic layer on the outer periphery of the conductive shaft. The elastic layer is made of urethane rubber, NBR (nitrile rubber), EPDM (ethylene propylene diene rubber), silicone rubber, or the like from which an electronic conductive agent such as carbon or a conductive filler or an ionic conductive agent is separated.
Further, as the shape of the elastic layer of the developing roller 41, for example, there is one having a radius of 19.6 mm and a length in the longitudinal direction of 348 mm.

  In the developing unit 2, a toner image is formed on the electrostatic latent image formed on the photosensitive drum 10 by the developing roller 41, the toner supply roller 71, and the layer forming blade 72. The toner image thus formed is transferred to the recording paper 9 (see FIG. 1).

The toner 3 stored in the toner cartridge 140 of the image forming unit 101 includes a polyester resin, a colorant, a charge control agent, and a release agent, and further an external additive (for example, hydrophobic silica) is added. The
The toner 3 becomes a pulverized shape having an average particle diameter of 8 μm by, for example, a pulverization method, and is used as a developer.

  Further, the image forming unit 101 removes the excess toner 3 attached to the photosensitive drum 10 without being transferred to the recording paper 9 (see FIG. 1), and cleans the surface of the photosensitive drum cleaning blade 63. And a photosensitive drum waste toner box 65 for collecting toner (waste toner) removed from the photosensitive drum 10 is provided.

As described above, the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c included in the image forming apparatus 100 illustrated in FIG. 1 all have the same configuration.
Hereinafter, as necessary, the elements constituting the black image forming unit 101k are indicated by the reference numerals added to the respective elements constituting the image forming unit 101 shown in FIG. The elements constituting 101y are indicated by the reference numerals with the subscript y added to the elements constituting the image forming unit 101, and the elements constituting the magenta image forming unit 101m are subscripted to the elements constituting the image forming unit 101. The elements constituting the cyan image forming unit 101c are denoted by reference numerals with a suffix c added to the elements constituting the image forming unit 101.

  Next, the configuration of the control system of the image forming apparatus 100 (see FIG. 1) will be described mainly with reference to FIG. 3 (see FIGS. 1 and 2 as appropriate).

As shown in FIG. 3, the control unit 102 constituting the control system of the image forming apparatus 100 includes a print control unit 20 as a control unit that mainly controls the image forming unit 101.
The print control unit 20 includes a CPU (Central Processing Unit) 13 and is connected to a memory 12 including a ROM (Read Only Memory) 12a and a RAM (Random Access Memory) 12b. Then, for example, the CPU 13 executes a program stored in the ROM 12a, and the print control unit 20 causes the image forming unit 101 (black image forming unit 101k, yellow image forming unit 101y, magenta image forming unit 101m, cyan image forming unit 101c). ) To control.
Furthermore, a higher-level device 103 (for example, a personal computer) that inputs image data of an image to be printed on the recording paper 9 to the image forming apparatus 100 is connected to the print control unit 20 via the interface unit 11, and further print control is performed. The unit 20 is connected with a humidity sensor 14 as a humidity measuring unit and a temperature sensor 15 as an air temperature measuring unit.
In the present embodiment, the humidity sensor 14 and the temperature sensor 15 constitute an environmental state detection unit.

The humidity sensor 14 and the temperature sensor 15 are sensors for measuring the atmospheric humidity (hereinafter referred to as ambient humidity) and the atmospheric temperature (hereinafter referred to as ambient temperature) of the ambient environment where the image forming apparatus 100 is installed, respectively. The print control unit 20 included in the control unit 102 of the image forming apparatus 100 according to the first embodiment can detect the ambient humidity and the ambient temperature.
In addition, various sensors 16 necessary for controlling the image forming apparatus 100 are connected to the print control unit 20. The various sensors 16 are sensors that detect the position of the recording paper 9, for example.

  The print control unit 20 provided in the control unit 102 includes a process control unit 30, a development voltage application unit 31 and a supply voltage application unit 32 as a voltage application unit, a layer formation voltage application unit 33, a charging voltage application unit 34, an exposure. A control unit 35 and a motor control unit 36 as a rotation drive unit are connected.

The process control unit 30 applies a positive high voltage set by the print control unit 20 to the transfer roller 51 in order to transfer the toner image formed on the photosensitive drum 10 to the recording paper 9.
The development voltage application unit 31 applies the surface potential DB (bias voltage) of the development roller 41 set by the print control unit 20 to form a toner image on the photosensitive drum 10 to the development roller 41.
The supply voltage application unit 32 applies the surface potential SB (bias voltage) of the toner supply roller 71 set by the print control unit 20 to supply the toner 3 to the developing roller 41 to the toner supply roller 71.
The layer formation voltage application unit 33 applies the surface potential of the layer formation blade 72 set by the print control unit 20 to regulate the toner amount of the toner image formed on the photosensitive drum 10 to the layer formation blade 72.
The surface potential of the layer forming blade 72 can be set to be equal to the surface potential DB of the developing roller 41, for example.

  The charging voltage application unit 34 has a function of applying a predetermined voltage set by the printing control unit 20 to the charging roller 21, and the exposure control unit 35 has the LED head 22 operated according to a control signal input from the printing control unit 20. The amount of light and the irradiation time of light irradiated on the photosensitive drum 10 are controlled.

  The motor control unit 36 includes a photosensitive drum motor 10a as an image carrier rotation driving unit that rotates the photosensitive drum 10, and a developing roller motor as a developer carrier rotation driving unit that rotates the developing roller 41. The frequency of the driving power supplied to 41a is controlled to control the rotational speeds of the photosensitive drum motor 10a and the developing roller motor 41a, that is, the rotational speeds of the photosensitive drum 10 and the developing roller 41.

  Further, a density sensor 91 is connected to the print control unit 20 via a density sensor control unit 37, and the print control unit 20 uses the toner density measured by the density sensor 91 from the density detection pattern transferred to the transfer belt 1. Can be detected.

  The control unit 102 is connected to the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c shown in FIG. 1, and is configured to control each image forming unit 101. Is done.

  Further, as shown in FIG. 3, the drum counter 18 as a rotation number measuring unit that measures the number of rotations of the photosensitive drum 10 of the image forming unit 101, and the image data input from the host device 103 are converted into dot data. The dot counter 19 as a dot number measurement part which measures the number of dots at the time may be provided.

The drum counter 18 determines the number of rotations of the photosensitive drums 10k, 10y, 10m, and 10c included in the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c of the image forming apparatus 100, respectively. Each of the measurement configurations is preferable.
The drum counter 18 increments the count value Dc when the photosensitive drum 10 rotates by a predetermined amount in order to form an image on a sheet of a predetermined size (for example, A4 size in the horizontal direction). Dc is input to the print control unit 20.
In other words, the count value Dc is a value indicating the rotation amount of the photosensitive drum 10.
The print controller 20 can calculate the number of rotations of the photosensitive drum 10 from the count value Dc input from the drum counter 18.

  The dot counter 19 is preferably configured to measure the number of dots of each color (black, yellow, magenta, cyan).

A control unit 102 included in the image forming apparatus 100 according to the first embodiment is configured as shown in FIG. 3, and includes a surface potential DB of the developing roller 41 (see FIG. 2) of the image forming unit 101 and a toner supply roller 71. The absolute value | DB-SB | of the potential difference of the surface potential SB (see FIG. 2) is set corresponding to the ambient humidity and ambient temperature of the image forming apparatus 100, and the absolute value of the set potential difference | DB-SB | The linear velocity ratio between the photosensitive drum 10 (see FIG. 2) and the developing roller 41 is set so as to correspond to the above.
For this reason, for example, the | DB-SB | environment correction table 400 shown in FIG. 4A is stored in advance in the ROM 12a of the memory 12 (see FIG. 3).

  The surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2) have a relationship of | DB | <| SB |, and the toner 3 (see FIG. 1) is negative. When the charging property is negative, the surface potential SB of the toner supply roller 71 is also a negative DC voltage. For example, when the surface potential DB of the developing roller 41 is “−200 V” and the potential difference | DB−SB | is “100 V”, the surface potential SB of the toner supply roller 71 is “−300 V”.

| DB-SB | The environmental correction table 400 indicates the ambient humidity of the environment in which the image forming apparatus 100 (see FIG. 1) is installed, for example, low humidity (5% to less than 35%), medium humidity (35% to 65%). Less than) and high humidity (65% to 90%), and a potential difference | DB-SB | corresponding to low humidity, medium humidity, and high humidity is set.
Furthermore, the ambient temperature of the environment in which the image forming apparatus 100 is installed is, for example, three stages: low temperature (5 ° C. to less than 15 ° C.), medium temperature (15 ° C. to less than 25 ° C.), and high temperature (25 ° C. to 35 ° C.). The potential difference | DB-SB | corresponding to the low temperature, medium temperature, and high temperature is set.
Thus, the | DB-SB | environment correction table 400 is a table showing the relationship between the ambient humidity, the ambient temperature, and the potential difference | DB-SB |.

  In the | DB-SB | environment correction table 400 shown in FIG. 4A, the ambient humidity and ambient temperature are divided into three stages, but the number of divisions is not limited. It may be divided into more than three stages.

Further, a linear velocity table 401 as shown in FIG. 4B is stored in advance in the ROM 12a (see FIG. 3) of the memory 12, for example.
The linear velocity table 401 shows the difference in potential | DB−SB | between the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2), and the linear velocity of the developing roller 41 as a photoconductor. It is a table which shows the relationship of the value (henceforth linear speed ratio S) remove | divided with the linear speed of the drum 10 (refer FIG. 2).

For example, when the photosensitive drum 10 is rotating at a linear speed of 140 mm / s and the linear speed ratio S is 1.2, the linear speed of the developing roller 41 is 168 mm / s.
As described above, the print control unit 20 can set the linear speed of the developing roller 41 in correspondence with the potential difference | DB−SB | with reference to the linear speed table 401.

  3 inputs a control signal to the developing roller motor 41a that rotationally drives the developing roller 41 (see FIG. 2) via the motor control unit 36, and the linear velocity of the developing roller 41 is The developing roller 41 can be rotationally driven at a rotational speed that achieves the calculated linear speed.

As described above, the print control unit 20 (see FIG. 3) of the image forming apparatus 100 according to the first embodiment uses the line of the developing roller 41 (see FIG. 2) with respect to the linear velocity of the photosensitive drum 10 (see FIG. 2). The speed can be set corresponding to the ambient humidity and the ambient temperature, and the developing roller 41 can be driven to rotate at a rotational speed that provides the set linear speed.
The print control unit 20 includes all the developing rollers 41k, 41y, 41m, and 41c included in the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c illustrated in FIG. It can be rotated by setting the linear velocity.

With reference to the flowchart shown in FIG. 5, the procedure by which the print control unit 20 sets the linear velocity of the developing roller 41 will be described (see FIGS. 1 to 4 as appropriate).
When the print control unit 20 detects that the image forming apparatus 100 is powered on (step S101), the humidity sensor 14 detects the ambient humidity where the image forming apparatus 100 is installed, and the temperature sensor 15 detects the ambient temperature. Is detected.
Hereinafter, the environmental state including the ambient temperature and the ambient humidity is referred to as an environmental state, and the detection of the ambient temperature and the ambient humidity by the print control unit 20 is referred to as detecting the environmental state.
That is, the print control unit 20 detects the environmental state (step S102).

For example, when the ambient temperature is 10 ° C. and the ambient humidity is 20%, the print control unit 20 determines that the environmental state is low temperature and low humidity, and when the ambient temperature is 22 ° C. and the ambient humidity is 60%, the print control unit. 20 determines that the environmental state is medium temperature and medium humidity. Furthermore, for example, when the ambient temperature is 27 ° C. and the ambient humidity is 80%, the print control unit 20 determines that the environmental state is high temperature and high humidity.
Further, the print control unit 20 may be configured to store the determination result in, for example, the RAM 12b provided in the memory 12.
For example, when the ROM 12a can write data such as a flash memory, the print control unit 20 may be configured to store the determination result in the ROM 12a.

The print control unit 20 that has detected the environmental state executes supply voltage correction (step S103).
In the supply voltage correction, the print control unit 20 determines the surface potential DB corresponding to the toner density from an automatic density correction table (not shown) indicating the relationship between the toner density detected by the density sensor 91 and the surface potential DB of the developing roller 41. Is set to, for example, “−200 V” and applied to the developing roller 41 via the developing voltage applying unit 31. “−200 V” applied to the developing roller 41 is an example, and is not limited to this value.
Further, the print control unit 20 refers to the | DB-SB | environment correction table 400 shown in FIG. 4A corresponding to the detected environmental state (ambient humidity and ambient temperature), and the surface of the developing roller 41. A potential difference | DB−SB | between the potential DB and the surface potential SB of the toner supply roller 71 is set.

For example, when the environmental state is low temperature and low humidity, the print control unit 20 extracts the correction value 50 with reference to the | DB-SB | environment correction table 400 and sets it as “−200 V, which is set as the surface potential DB of the developing roller 41. The negative voltage “−250 V” obtained by adding the correction value 50 to the absolute value “200 V” is set as the surface potential SB of the toner supply roller 71. Then, the print control unit 20 applies “−250 V” to the toner supply roller 71 via the supply voltage application unit 32.
When the environmental state is medium temperature and medium humidity, the print control unit 20 refers to the | DB-SB | environment correction table 400, extracts the correction value 175, and sets the surface potential DB of the developing roller 41 as “−. A negative voltage “−375 V” obtained by adding the correction value 175 to the absolute value “200 V” of “200 V” is set as the surface potential SB of the toner supply roller 71. Then, the print control unit 20 applies “−375 V” to the toner supply roller 71 via the supply voltage application unit 32.
Similarly, when the environmental state is high temperature and high humidity, the print control unit 20 applies “−430 V” as the surface potential SB to the toner supply roller 71.

  The correction values described in the | DB-SB | environment correction table 400 shown in FIG. 4A are examples, and the correction values are not limited to these values.

In this way, the print control unit 20 performs supply voltage correction (step S103), sets the surface potential DB of the developing roller 41 and the surface potential SB of the toner supply roller 71 in accordance with the detected environmental state, A surface potential DB and a surface potential SB are applied to the developing roller 41 and the toner supply roller 71, respectively.
Note that more detailed contents of the supply voltage correction are described in Patent Document 1 (Japanese Patent Laid-Open No. 2004-029681) filed by the present applicant.

Further, the print control unit 20 applies a voltage of “−1000 V”, for example, to the charging roller 21 (21k, 21y, 21m, 21c) via the charging voltage application unit 34, and further, the photosensitive drum 10 (10k, 10k, 10y, 10m, 10c) are uniformly charged, and, for example, “+4000 V” is applied to the transfer roller 51 (51k, 51y, 51m, 51c). These values are values set in advance, for example.
The above-mentioned “−1000 V” and “+4000 V” are examples, and are not limited to these values.

Next, the print control unit 20 performs linear velocity correction of the developing roller 41 (step S104).
In executing the linear velocity correction, first, the print control unit 20 sets the linear velocity of the photosensitive drum 10. The linear velocity of the photosensitive drum 10 is set to a preset value such as “140 mm / s”, for example. The linear velocity “140 mm / s” of the photosensitive drum 10 is an example, and is not limited to this value.
Further, the print control unit 20 refers to the linear velocity table 401 shown in FIG. 4B with the potential difference | DB−SB | calculated by executing the supply voltage correction as a parameter, and develops the photosensitive drum 10 with respect to the linear velocity. A linear speed ratio S that is a ratio of linear speeds of the rollers 41 is extracted.

For example, when the environmental state is low temperature and low humidity, the potential difference | DB−SB | is “50 V”, and therefore the print control unit 20 refers to the linear speed table 401 and extracts 1.6 as the linear speed ratio S. . When the linear velocity of the photosensitive drum 10 is “140 mm / s”, the linear velocity ratio of 1.6 is multiplied to set the linear velocity of the developing roller 41 to “224 mm / s”.
Further, when the environmental state is medium temperature and medium humidity, the potential difference | DB−SB | is “175 V”, so the print control unit 20 refers to the linear velocity table 401 and extracts 1.2 as the linear velocity ratio S. To do. When the linear velocity of the photosensitive drum 10 is “140 mm / s”, the linear velocity ratio 1.2 is multiplied to set the linear velocity of the developing roller 41 to “168 mm / s”.
Similarly, when the environmental condition is high temperature and high humidity, the print control unit 20 extracts 1.0 as the linear speed ratio S, and when the linear speed of the photosensitive drum 10 is “140 mm / s”, the developing roller 41 The linear velocity is set to “140 mm / s”.

In addition, the value of the linear velocity ratio S described in the linear velocity table 401 shown in FIG. 4B is an example, and the linear velocity ratio S is not limited to these values.
Further, the value of the potential difference | DB-SB | as a parameter for extracting the linear velocity ratio S is not limited to the value described in the linear velocity table 401 shown in FIG.

  The print control unit 20 inputs a control signal to the photosensitive drum motor 10a that rotationally drives the photosensitive drum 10 through the motor control unit 36, and rotationally drives the photosensitive drum 10 at the set linear speed. Then, a control signal is input to the developing roller motor 41a that rotationally drives the developing roller 41 via the motor control unit 36, and the developing roller 41 is rotationally driven at the set linear speed.

Then, the print control unit 20 executes density correction (step S105).
The density correction is a process for correcting the toner density when an image is printed on the recording paper 9. For example, the print control unit 20 forms a density detection pattern by the image forming unit 101, and the transfer belt 1 in the width direction, for example. Transfer to the center.
The density detection patterns are respectively formed by the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c, and are sequentially transferred to the transfer belt 1.
The density sensor 91 detects the density detection pattern transferred to the transfer belt 1 and outputs a signal (for example, a voltage signal) indicating the position and density of the density detection pattern.
The print control unit 20 corrects the toner density when printing an image on the recording paper 9 by adjusting the development parameters of the image forming unit 101 according to the signal input from the density sensor 91. This density correction is preferably executed for each color (black, yellow, magenta, cyan).

  Then, the print control unit 20 executes printing (step S106), and forms (prints) an image on the recording paper 9.

  As described above, the image forming apparatus 100 (see FIG. 1) according to the first embodiment uses the environmental state (ambient humidity and ambient temperature) as parameters, and the surface potential DB of the developing roller 41 (see FIG. 2) and the toner supply. The potential difference | DB−SB | of the surface potential SB of the roller 71 (see FIG. 2) can be set, and the linear speed (rotational speed) of the developing roller 41 is set using the set potential difference | DB−SB | as a parameter. Can be set. In addition, “fogging” that occurs during printing can be improved.

  The print control unit 20 performs the procedure shown in FIG. 5 on all the image forming units 101 of the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c. Run.

The results of measuring “fogging” as the color difference ΔE are shown below.
As a specific method, the Lab of the recording paper 9 (refer to FIG. 1) in an unprinted state as a reference measured with a spectrocolorimeter (CM-2600d manufactured by KONICA MINOLTA) and the recording paper 9 on which an image is printed are recorded. The “fog” was shown by the color difference ΔE obtained by comparing the Lab of the blank paper portion (non-image portion). In this case, the smaller the color difference ΔE, the more “fogging” is improved.

As shown in FIG. 6, when the environmental condition is low temperature and low humidity, when the linear speed ratio S is 1.2, the surface potential DB of the developing roller 41 (see FIG. 2) and the toner supply roller 71 (see FIG. 2). When the potential difference | DB−SB | of the surface potential SB of the toner is reduced from “175 V” to “50 V”, the color difference ΔE increases from 0.5 to 1. That is, “fogging” is worsened.
However, if the linear velocity ratio S is set to 1.4 when the potential difference | DB−SB | is “50 V”, the color difference ΔE can be reduced to 0.5. That is, deterioration of “fogging” can be suppressed.

  When the potential difference | DB−SB | between the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2) becomes small, the toner 3 attached to the developing roller 41 (see FIG. 2). However, by increasing the linear speed (rotational speed) of the developing roller 41, the decrease in the charge amount of the toner 3 can be suppressed and the occurrence of “fogging toner” having a low charge amount can be suppressed. It is possible to suppress the deterioration of “fog”.

  Further, as shown in FIG. 7, when the environmental condition is high temperature and high humidity, the potential difference | DB between the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2). -SB | is set large. As a result, the amount of toner 3 (see FIG. 2) adhering to the developing roller 41 and the charge amount can be increased, and “fogging” does not deteriorate even if the linear velocity ratio S is reduced.

  It is known that “fogging” can be improved by increasing the linear velocity (rotational speed) of the developing roller 41 (see FIG. 2). However, if the linear velocity of the developing roller 41 is increased, the photosensitive drum 10 (see FIG. 2). The toner 3 (see FIG. 2) melts and adheres to the developing roller 41 and the layer forming blade 72 (see FIG. 2), and a streak pattern may occur on the recording paper 9 (see FIG. 1). is there.

In the image forming apparatus 100 (see FIG. 1) according to the first embodiment, the linear speed ratio S between the developing roller 41 (see FIG. 2) and the photosensitive drum 10 (see FIG. 2) is determined based on the environmental conditions (ambient humidity and ambient humidity). By setting (ambient temperature) as a parameter, for example, when the environmental state is high temperature and high humidity, the linear velocity of the developing roller 41 can be reduced, and the generation of a streak pattern can be suitably suppressed.
Furthermore, by setting the linear speed ratio S using the environmental conditions (ambient humidity and ambient temperature) as parameters, there is an excellent effect that deterioration of “fogging” can be suitably suppressed.

<< Modification 1 >>
The image forming apparatus 100 (see FIG. 1) according to the first embodiment uses the environmental state as a parameter, and the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2). The potential difference | DB-SB | is set. However, as a first modification, for example, the potential difference | DB-SB is increased as the usage time after the image forming unit 101 (see FIG. 1) starts to be used. It may be configured to correct |.

  For example, the print control unit 20 (see FIG. 3) of the control unit 102 starts using the image forming unit 101 (see FIG. 2) from the count value Dc input from the drum counter 18 (see FIG. 3). The number of rotations N of the photosensitive drum 10 (see FIG. 2) is calculated, and the calculated number of rotations N is used as the usage time of the image forming unit 101.

  Further, for example, a time correction table 801 shown in FIG. 8A is set in advance and stored in the ROM 12a of the memory 12 (see FIG. 3). The temporal correction table 801 is a table showing the relationship between the number of rotations N of the photosensitive drum 10, that is, the usage time of the image forming unit 101 and the correction value (temporal correction value R1) of the potential difference | DB-SB |.

  Then, the print control unit 20 executes the supply voltage correction in step S103 of the flowchart shown in FIG. 5, and the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential of the toner supply roller 71 (see FIG. 2). When the potential difference | DB−SB | of SB is set, the number of rotations N of the photosensitive drum 10 is calculated from the count value Dc input from the drum counter 18, and the calculated number of rotations N is used as a parameter. The temporal correction value R1 is extracted with reference to the temporal correction table 801 shown in FIG.

For example, when the number of rotations N of the photosensitive drum 10 is “12000”, the print control unit 20 refers to the temporal correction table 801 and extracts “−50” as the temporal correction value R1.
Then, the print control unit 20 corrects the calculated potential difference | DB-SB | with the temporal correction value R1.
For example, when the print control unit 20 calculates “175 V” as the potential difference | DB−SB |, and the temporal correction value R1 is “−50”, the print control unit 20 displays “potential difference | DB−SB | + time. The correction value R1 "is executed to correct the potential difference | DB-SB | to" 125V ".
Then, the print control unit 20 executes step S104 of the flowchart shown in FIG. 5, and sets the linear velocity of the developing roller 41 (see FIG. 2) using the corrected potential difference | DB-SB | as a parameter.

  In the temporal correction table 801 shown in FIG. 8A, for example, the temporal correction value R1 for correcting the potential difference | DB−SB | to be smaller as the number of rotations N of the photosensitive drum 10 (see FIG. 2) increases. Set.

When the usage time of the image forming unit 101 (see FIG. 2) becomes long, the toner 3 (see FIG. 2) is deteriorated with time and is easily overcharged, and “dirt” is likely to occur.
Accordingly, the potential difference | DB-SB | is corrected so as to decrease as the number of rotations N of the photosensitive drum 10 (see FIG. 2) increases, that is, as the usage time of the image forming unit 101 increases. Suppresses excessive charging.
As described above, the potential difference | DB−SB | between the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2) is used as a parameter and the number N of rotations of the photosensitive drum 10 as a parameter. By correcting with the set time-dependent correction value R1, it is possible to suppress excessive adhesion of the toner 3 to the photosensitive drum 10 and to suppress deterioration in print quality.

  Note that the values of the temporal correction value R1 and the rotation number N described in the temporal correction table 801 shown in FIG. 8A are examples, and the temporal correction value R1 and the rotation number N are limited to these values. It is not a thing.

<< Modification 2 >>
As a second modification, the potential difference | DB−SB | may be corrected to be larger as the dot formation density when the image data input from the host device 103 (see FIG. 3) is converted into dot data is larger.

For example, the print control unit 20 (see FIG. 3) of the control unit 102 generates the image data input from the host apparatus 103 (see FIG. 3) before the image data is input from the host apparatus 103. The number of rotations N of the photosensitive drum 10 (see FIG. 2) calculated from the total dot number Dt of the dot data thus obtained, the count value Dc input from the drum counter 18 (see FIG. 3), and 1 for the photosensitive drum 10. The average print dot formation density Du is calculated from the maximum number of dots Dm that can be printed by rotation.
The average print dot formation density Du can be calculated by the following equation (1), for example.
Du = (Dt / (Dm × N)) (1)

Note that the maximum number of dots Dm that can be printed by one rotation of the photosensitive drum 10 is determined in advance by measurement or the like, and is, for example, a value stored in the ROM 12a (see FIG. 3) of the memory 12.
The total dot number Dt of the dot data can be calculated by accumulating the dot number Do measured by the dot counter 19 (see FIG. 3) when image data is input from the host device 103 and converted to dot data.

  Further, for example, a print density correction table 802 shown in FIG. 8B is set in advance and stored in the ROM 12a of the memory 12 (see FIG. 3). The print density correction table 802 is a table showing the relationship between the average print dot formation density Du and the correction value (print density correction value R2) of the potential difference | DB-SB |.

  Then, the print control unit 20 executes the supply voltage correction in step S103 of the flowchart shown in FIG. 5, and the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential of the toner supply roller 71 (see FIG. 2). When setting the potential difference | DB−SB | of the SB, the average print dot formation density Du is calculated, and the print density correction value is calculated by referring to the print density correction table 802 using the calculated average print dot formation density Du as a parameter. R2 is extracted.

For example, when the calculated average print dot formation density Du is 40%, the print control unit 20 refers to the print density correction table 802 and extracts “+50” as the print density correction value R2.
Then, the print control unit 20 corrects the calculated potential difference | DB-SB | with the print density correction value R2.
For example, if the printing control unit 20 calculates “175 V” as the potential difference | DB−SB | and the printing density correction value R2 is “+50”, the “potential difference | DB−SB | + printing density correction value R2”. To correct the potential difference | DB-SB | to "225V".

  Then, the print control unit 20 executes step S104 of the flowchart shown in FIG. 5, and sets the linear velocity of the developing roller 41 (see FIG. 2) using the corrected potential difference | DB-SB | as a parameter.

  The larger the average print dot formation density Du is, the more toner 3 (see FIG. 2) is used, and the toner supply roller 71 (see FIG. 2) has a reduced ability to transport toner 3 due to crushing of the cells. is expected. Therefore, the printing density correction value R2 is increased to increase the potential difference | DB-SB | as the average printing dot formation density Du increases, and the toner 3 conveying ability is electrically improved.

  As described above, the potential difference | DB−SB | between the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2) is larger than the average print dot formation density Du of the image data. By correcting with the print density correction value R2 that increases as much as possible, for example, a decrease in the conveyance capability of the toner 3 (see FIG. 2) of the toner supply roller 71 can be compensated, and the printing quality can be stabilized.

  Note that the print density correction value R2 and the average print dot formation density Du described in the print density correction table 802 shown in FIG. 8B are examples, and the print density correction value R2 and the average print dot formation density Du The value of is not limited to these values.

<< Modification 3 >>
Further, as a third modification, for example, the potential difference | DB−SB | between the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2) is represented by the image forming apparatus 100 (FIG. 1 may be appropriately changed.

  For example, a user correction table 803 shown in FIG. 8C is stored in advance in the ROM 12a of the memory 12 (see FIG. 3). The user correction table 803 is a table showing the relationship between the selection value input by the user or the like and the correction value (user correction value R3) of the potential difference | DB-SB |.

Further, the image forming apparatus 100 (see FIG. 1) includes a data input device (keyboard or the like) (not shown).
For example, the user selects one of predetermined selection values “setting 1” to “setting 5” and inputs the selected value to the image forming apparatus 100 via a data input device (not shown).

  Then, the print control unit 20 executes the supply voltage correction in step S103 of the flowchart shown in FIG. 5, and the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential of the toner supply roller 71 (see FIG. 2). When setting the potential difference | DB−SB | of SB, the user correction value R3 is extracted by referring to the user correction table 803 using the selection value input by the user as a parameter.

For example, when the selection value input by the user to the image forming apparatus 100 (see FIG. 1) is “setting 2”, the print control unit 20 refers to the user correction table 803 and extracts “−25” as the user correction value R3. To do.
Then, the print control unit 20 corrects the calculated potential difference | DB-SB | with the user correction value R3.
For example, when the print control unit 20 calculates “175 V” as the potential difference | DB−SB | and the user correction value R3 is “−25”, the “potential difference | DB−SB | + user correction value R3” is set. This is executed to correct the potential difference | DB−SB | to “150V”.

  Then, the print control unit 20 executes step S104 of the flowchart shown in FIG. 5, and sets the linear velocity of the developing roller 41 (see FIG. 2) using the corrected potential difference | DB-SB | as a parameter.

  As described above, in Modification 3, the user who uses the image forming apparatus 100 (see FIG. 1) can detect the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential of the toner supply roller 71 (see FIG. 2). The SB potential difference | DB-SB | can be appropriately changed.

  For example, in the third modification, when the user who uses the image forming apparatus 100 (see FIG. 1) determines that the print quality has deteriorated visually, for example, the surface potential DB of the developing roller 41 (see FIG. 2) and the toner The print quality can be quickly restored by changing the setting of the potential difference | DB-SB | of the surface potential SB of the supply roller 71 (see FIG. 2) as appropriate.

  Note that the user correction value R3 and the set value described in the user correction table 803 shown in FIG. 8C are examples, and the user correction value R3 and the set value are not limited to these values.

  In addition, the above-described modification 1 to modification 3 can be appropriately combined. In the case of a configuration in which modification 1, modification 2, and modification 3 are combined, the print control unit 20 (see FIG. 3) The supply voltage correction in step S103 of the flowchart shown in FIG. 5 is executed, and the potential difference | DB−SB | between the surface potential DB of the developing roller 41 (see FIG. 2) and the surface potential SB of the toner supply roller 71 (see FIG. 2) is obtained. At the time of setting, the potential difference | DB−SB | is corrected with the temporal correction value R1, the print density correction value R2, and the user correction value R3.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described.
The image forming apparatus according to the second embodiment has the same configuration as that of the image forming apparatus 100 according to the first embodiment (see FIG. 1). In particular, as shown in FIG. Is preferably provided in the control unit 102 as a count value Dc.

  Further, the drum counter 18 (see FIG. 3) provided in the image forming unit 101 is provided in each of the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c shown in FIG. It is preferable that the rotation amount of the photosensitive drums 10k, 10y, 10m, and 10c can be individually measured.

The drum counter 18 (see FIG. 3) inputs the measured rotation amount of the photosensitive drum 10 to the print controller 20 as the count value Dc. With this configuration, the print control unit 20 can individually calculate the number of rotations N of the photosensitive drums 10k, 10y, 10m, and 10c.
In the image forming apparatus 100 according to the second embodiment, the print control unit 20 calculates the rotation number N of the photosensitive drum 10 from the count value Dc input from the drum counter 18 and accumulates the calculated rotation number N. Thus, the cumulative rotation number Nl is calculated.
Further, the print control unit 20 acquires the number of rotations indicating the life of the image forming unit 101 (hereinafter referred to as a limit rotation number Nm).

In the second embodiment, the lifetime of the image forming unit 101 (see FIG. 2) is, for example, that the photosensitive drum 10 (see FIG. 2) is in a state where the linear speed ratio S is set to 1.2 as a reference value. Set when 30000 rotations. That is, the limit rotation number Nm is set to 30000.
Further, the reference value of the linear velocity ratio S is hereinafter referred to as a reference linear velocity ratio Sf.
The reference linear velocity ratio Sf and the limit rotation number Nm are preferably stored in advance in the ROM 12a (see FIG. 3) of the memory 12, for example.
The reference linear speed ratio Sf value 1.2 and the limit rotation speed Nm value 30000 for setting the lifetime of the image forming unit 101 are examples, and the reference linear speed ratio Sf and the limit rotation speed Nm are set as values. It is not limited to these values.

The operation of the image forming apparatus 100 according to the second embodiment will be described mainly with reference to the flowchart shown in FIG. 9 (see FIGS. 1 to 8 as appropriate).
In the procedure shown in FIG. 9, detailed description of the same processing as that shown in FIG. 5 is omitted.

When the print control unit 20 detects that the image forming apparatus 100 is powered on (step S201), the print control unit 20 resets the drum count of the drum counter 18 (step S202). That is, the print control unit 20 clears the calculated cumulative number of rotations Nl (Nl _NEW , Nl _OLD ) and the count value Dc measured by the drum counter 18. Nl _NEW and Nl _OLD will be described later.

  Then, as in the first embodiment, the print control unit 20 detects the environmental state (step S203), corrects the supply voltage (step S204), corrects the linear speed of the developing roller 41 (step S205), and corrects the density (step). The procedure proceeds in the order of S206), and the potential difference | DB−SB | between the surface potential DB of the developing roller 41 and the surface potential SB of the toner supply roller 71, the linear speed (rotational speed) of the toner supply roller 71, and the line of the developing roller 41 Set the speed (rotation speed). Further, the print control unit 20 executes printing by executing a print job (step S207), and forms (prints) an image on the recording paper 9.

After executing the print job, the print control unit 20 calculates the number of rotations N of the photosensitive drum 10 from the count value Dc input from the drum counter 18, and further calculates the calculated number N of rotations to the following equation (2). The accumulated number of rotations Nl is calculated by using (Step S208).
Nl _NEW = Nl _OLD + N x S / Sf (2)
In Expression (2), Nl _OLD is the cumulative number of rotations Nl until the previous print job is executed, and is cleared to “0” by execution of step S202 immediately after the power is turned on. Nl _NEW is a new cumulative number of rotations Nl set after execution of the print job.

The print control unit 20 stores the set new accumulated number of rotations Nl _NEW in the RAM 12 b of the memory 12.
Further, when the ROM 12a is, for example, a flash memory and data can be written, the print control unit 20 may store the calculated new accumulated rotation number Nl _NEW in the ROM 12a.

For example, when executing the first print job after the power is turned on, the print control unit 20 sets the linear speed ratio S to 1.4, and the number of rotations N calculated from the count value Dc input from the drum counter 18 is 100. In this case, since Nl _OLD is “0”, the print control unit 20 calculates the cumulative number of rotations Nl _NEW = 117 as Nl _NEW = 0 + 100 × 1.4 / 1.2.

Thereafter, when executing the print job, the print control unit 20 (see FIG. 3) uses the expression (2) by setting the accumulated number of rotations Nl _NEW set after the end of the print job executed immediately before as Nl _OLD , and a new one. Set the cumulative number of revolutions Nl _NEW .

  When the count value Dc input from the drum counter 18 is increased by ΔDc in the execution of one print job, the print control unit 20 executes the print job from the increment ΔDc of the count value Dc. The number N of rotations of the photosensitive drum 10 can be calculated.

When the cumulative number of rotations Nl (Nl _NEW ) is smaller than a predetermined limit number of rotations Nm (for example, Nm = 30000) (step S209 → No), the print control unit 20 measures the drum counter 18. The number of rotations N is cleared (step S210).
The print control unit 20, the accumulated number of rotations Nl _NEW set in step S208, sets the accumulated rotation number Nl _OLD until execution of the current print job (step S211).
Then, the procedure returns to step S203.
On the other hand, when the cumulative number of rotations Nl (Nl _NEW ) calculated in step S208 is equal to or greater than the limit number of rotations Nm (step S209 → Yes), the image forming unit 101 has a lifetime on display means (monitor, warning lamp, etc.) not shown. That is, the image forming unit life display is displayed (step S212).

  The print control unit 20 performs the procedure shown in FIG. 9 on all the image forming units 101 of the black image forming unit 101k, the yellow image forming unit 101y, the magenta image forming unit 101m, and the cyan image forming unit 101c. Run.

For example, when the film provided on the photosensitive surface of the photosensitive drum 10 (see FIG. 2) is consumed, the photosensitive drum 10 cannot be charged, and the printing quality is deteriorated.
The amount of film consumption on the photosensitive drum 10 (the amount of film removal) is determined by the amount of contact with the developing roller 41 (see FIG. 2), and the film consumption on the photosensitive drum 10 increases as the linear velocity of the developing roller 41 increases. The amount increases, and the smaller the linear velocity of the developing roller 41, the smaller the amount of film consumed on the photosensitive drum 10.
That is, as the linear velocity ratio S increases, the amount of film consumption on the photosensitive drum 10 increases, and the life of the image forming unit 101 (see FIG. 2) is shortened.

Therefore, in the image forming apparatus 100 (see FIG. 1) according to the second embodiment, the linear speed ratio S set by the print control unit 20 (see FIG. 3) is the reference linear speed ratio Sf (for example, 1.2). ), The number of rotations N measured by the drum counter 18 is apparently increased and added, and the accumulated number of rotations Nl is greatly corrected to make the image forming unit 101 (see FIG. 2). ) To shorten the life.
That is, when the linear velocity of the developing roller 41 (see FIG. 2) is large and the amount of film consumption on the photosensitive drum 10 is large, the life of the image forming unit 101 is set to be short.
With this configuration, the user can operate so as to increase the frequency of maintenance, for example. For example, the occurrence of “dirt” can be suppressed by maintaining the image forming unit 101 before “dirt” occurs.

On the other hand, when the linear velocity ratio S set by the print control unit 20 (see FIG. 3) is smaller than the reference linear velocity ratio Sf (for example, 1.2), the drum counter 18 measures using the equation (2). The lifetime N of the image forming unit 101 (see FIG. 2) is set longer by correcting the accumulated number of rotations Nl to be small by adding the number of rotations N apparently.
That is, when the linear velocity of the developing roller 41 (see FIG. 2) is small and the amount of film consumption on the photosensitive drum 10 is small, the lifetime of the image forming unit 101 is set to be long. With this configuration, for example, the user can operate the image forming apparatus 100 (see FIG. 1) so as to reduce the frequency of maintenance within a range in which “dirt” does not occur, thereby reducing the maintenance cost. Operation costs can be reduced.

As described above, the image forming apparatus 100 (see FIG. 1) according to the second embodiment performs image processing in accordance with the linear speed ratio S set by the print control unit 20 (see FIG. 3) when executing a print job. The lifetime of the forming unit 101 (see FIG. 2) can be set.
Therefore, the user can accurately know the lifetime of the image forming unit 101. In addition, the image forming unit 101 can be maintained at a suitable timing, and the operation cost of the image forming apparatus 100 (see FIG. 1) can be reduced and the stable print quality can be maintained.

The example in which the present invention is applied to a tandem image forming apparatus has been described above. However, the present invention is applicable to a monochrome machine having a monochromatic image forming unit or a four-cycle image forming apparatus having a single image carrier. Can also be applied.
1 is a direct printing type image forming apparatus, but the present invention is not limited to a direct printing type image forming apparatus, and a two-component developing type image forming apparatus or a so-called image forming apparatus. The present invention can also be applied to an intermediate transfer type image forming apparatus, an MFP (Multifunction Printer), a fax machine, and a copying machine.

3 Toner (Developer)
10 Photosensitive drum (image carrier)
14 Humidity sensor (humidity measurement unit, environmental condition detection unit)
15 Temperature sensor (temperature measurement unit, environmental condition detection unit)
18 Drum Counter (Rotation Count Measurement Unit)
20 Print control unit (control unit)
22 LED head (exposure section)
31 Development voltage application part (voltage application part)
32 Supply voltage application unit (voltage application unit)
36 Motor control unit (rotation drive unit)
41 Developing roller (developer carrier)
71 Toner supply roller (developer supply body)
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Image forming part

Claims (4)

An image carrier on which an electrostatic latent image is formed by exposure with light emitted by an exposure unit;
A developer carrier for attaching a developer to the image carrier;
A developer supplier for supplying the developer to the developer carrier;
A voltage applying unit for applying a respective different bias voltages the developer carrying member to said developer supplying member,
A rotation driving unit that causes the rotation driving the image bearing member and said developer carrying member,
A linear velocity ratio between the image carrier and the developer carrier is set, and the rotation driving unit is controlled so that the image carrier and the developer carrier are rotationally driven at the set linear velocity ratio. An image forming apparatus comprising:
Wherein the control unit is configured so that the linear speed value as the difference of the bias voltage respectively to the developer carrying member and said developer supply member is applied is small the developer carrier increases, the linear velocity ratio An image forming apparatus comprising: setting. A humidity measurement unit that measures the humidity of the atmosphere and an air temperature measurement unit that measures the atmospheric temperature;
The controller is
Setting the difference in the bias voltage based on at least one of the atmospheric humidity and the atmospheric temperature;
Wherein by controlling a voltage application unit, according to claim 1, characterized in that so that the difference between the bias voltage set, applying a respective different said bias voltage said developer carrying member to the developer supply member the image forming apparatus according to. A rotation number measuring unit for measuring the number of rotations of the image carrier,
The control unit calculates the cumulative number of rotations by accumulating the number of rotations of the image carrier measured by the rotation number measurement unit, and corrects the cumulative number of rotations according to the linear speed ratio ,
3. The image forming apparatus according to claim 1, wherein the life of the image carrier is determined based on the corrected cumulative number of rotations. The controller is
When the linear speed ratio is larger than a preset reference value, the cumulative number of rotations is corrected so as to increase,
The image forming apparatus according to claim 3 , wherein when the linear velocity ratio is smaller than the reference value, the cumulative number of rotations is corrected to be small.

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