JP2018169477A - Image forming apparatus - Google Patents

Abstract

The present invention provides means for suppressing deterioration in image quality when printing is continuously performed at a low speed.
A rotatable image carrier, a rotatable developing roller for supplying a developer regulated by a regulating blade to the image carrier, rotation of the image carrier and the developer carrier. And a control unit 21 that calculates an accumulated value obtained by accumulating the addition value based on the rotation, and the control unit rotates at a rotation speed that is lower than a predetermined rotation speed of the developer carrier. In this case, when the cumulative value reaches a threshold value, the developer carrying member is idled.
[Selection] Figure 2

Description

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

  Some conventional image forming apparatuses perform printing by forming a developer image on a recording medium by changing the printing speed according to the type (for example, thickness) of the recording medium to be used (for example, , See Patent Document 1).

JP 2010-181728 A

However, the conventional technique has a problem in that image quality may be deteriorated when printing is continuously performed at a low speed.
An object of the present invention is to solve such a problem, and an object of the present invention is to suppress deterioration in image quality when printing is continuously performed at a low speed.

  Therefore, the present invention provides a rotatable image carrier, a rotatable developer carrier that supplies a developer regulated by a regulating member to the image carrier, the image carrier, and the developer carrier. A control unit that controls rotation and calculates a cumulative value obtained by accumulating an addition value based on the rotation, and the control unit is configured to rotate the developer carrier at a rotational speed that is slower than a predetermined rotational speed. In the case of rotation, when the accumulated value reaches a threshold value, the developer carrying member is idled.

  According to the present invention as described above, an effect is obtained that it is possible to suppress a decrease in image quality when printing is continuously performed at a low speed.

1 is a schematic sectional side view of an image forming apparatus according to a first embodiment. 1 is a block diagram showing a control configuration of an image forming apparatus according to a first embodiment. Flowchart showing the flow of idling control processing in the first embodiment Flowchart showing the flow of idling control processing in the first embodiment

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional side view of an image forming apparatus according to the first embodiment.
In FIG. 1, an image forming apparatus 100 is, for example, an electrophotographic printer. The image forming apparatus 100 includes developing units 12W, 12M, 12Y, and 12C, an LED (Light Emitting Diode) head 3, a fixing device 13, a tray 28, a hopping roller 29, a registration roller 30, and a discharge roller 31. And a transfer belt 32, a transfer roller 5, a drive roller 33, an idle roller 34, a belt cleaning device 35, and a temperature / humidity sensor 36.

  The developing units 12W, 12M, 12Y, and 12C form toner images as developer images of respective colors with toner as a developer. For example, the developing unit 12W forms a toner image with white (W) toner, the developing unit 12M forms a toner image with magenta (M) toner, and the developing unit 12Y uses yellow (Y) toner. A toner image is formed, and the developing unit 12C forms a toner image with cyan (C) toner.

Since the developing units 12W, 12M, 12Y, and 12C have the same configuration except for the color of the toner to be handled, the configuration will be described by taking the developing unit 12W as an example.
The developing unit 12 </ b> W includes a photosensitive drum 1, a charging roller 2, a developing device 4, and a cleaning device 6.

The photosensitive drum 1 as an image carrier is one on which an electrostatic latent image is formed and is rotatably supported. The photosensitive drum 1 can store electric charge on the surface, and can remove the electric charge on the surface by exposure to form an electrostatic latent image.
In this embodiment, a photosensitive drum 1 is used in which a charge generation layer having a thickness of 0.5 μm and a charge transport layer having a thickness of 20 μm are provided on an aluminum base tube having a thickness of 0.75 mm and an outer diameter of 30 mm. did.

  The charging roller 2 as a charging device is rotatably supported so as to come into contact with the surface of the photosensitive drum 1 with a constant pressure. The charging roller 2 is a device for uniformly charging the surface of the photosensitive drum 1. For example, the charging roller 2 is coated with a conductive elastic body such as epichlorohydrin around a conductor made of a SUS material so as to come into contact with the photosensitive drum 1. Is arranged.

  The LED head 3 as an exposure device selectively exposes the surface of the photosensitive drum 1 uniformly charged by the charging roller 2 to form an electrostatic latent image on the surface of the photosensitive drum 1. The LED head 3 includes an LED element, an LED driving element, and a lens array, and is disposed at a position where light emitted from the LED element forms an image on the surface of the photosensitive drum 1.

  The developing device 4 is a device that develops a toner image on the electrostatic latent image formed on the photosensitive drum 1. The developing device 4 includes a developing roller 8, a supply roller 9, and a regulating blade 10, and is supplied with toner from a toner cartridge.

  The developing roller 8 as a developer carrying member develops the electrostatic latent image formed on the photosensitive drum 1 and is rotatably supported so as to contact the surface of the photosensitive drum 1 with a constant pressure. Is. The developing roller 8 supplies the toner regulated by the regulating blade 10 and regulated by the regulating blade 10 to the electrostatic latent image formed on the photosensitive drum 1 and develops it to form a toner image.

The developing roller 8 has a configuration in which an elastic layer is disposed in a roll shape on a conductive shaft (core metal) made of a SUS material and has a surface layer covering the elastic layer.
In this example, urethane rubber or silicone rubber was used for the elastic layer, and the surface layer was treated with a urethane solution, or coated with acrylic resin or acrylic-fluorine copolymer resin. . Carbon black was added to the surface layer of the acrylic resin and acrylic-fluorine copolymer resin in order to impart conductivity.

The supply roller 9 as a developer supply means is disposed so as to contact the surface of the development roller 8 with a constant pressure, and supplies toner to the development roller 8.
The supply roller 9 is formed of a conductive shaft (core metal) made of SUS material and an elastic layer. The elastic layer is a conductive silicone rubber foam layer or a conductive urethane rubber foam layer. In order to give this elastic layer semiconductivity, acetylene black, carbon black or the like is added.

The regulating blade 10 as a regulating member is arranged so that the tip portion is pressed against the surface of the developing roller 8 and regulates the toner supplied from the developing roller 8 to a predetermined thickness.
The regulating blade 10 is made of SUS having a plate thickness of 0.08 mm, and the contact portion with the developing roller 8 is bent. The radius of curvature R of the bent part after bending was 0.2 mm, and the linear pressure against the developing roller 8 was 30 gf / cm. However, the radius of curvature R and the linear pressure of the regulating blade 10 are not limited to this, and can be adjusted according to the toner amount on the developing roller 8 and the toner charge amount.

The transfer roller 5 transfers the toner image formed on the photosensitive drum 1 to the recording medium P or the transfer belt 32, and is made of, for example, a conductive foaming elastic body.
The cleaning device 6 scrapes and discards toner remaining due to non-transfer on the photosensitive drum 1 and waste toner moved from the developing device 4 onto the photosensitive drum 1. The cleaning device 6 includes a cleaning blade 11 using rubber, for example, and is arranged so that the tip of the cleaning blade 11 comes into contact with the surface of the photosensitive drum 1.

The tray 28 stores recording media in a stacked manner.
The hopping roller 29 feeds the recording medium accommodated in the tray 28 one by one in the medium conveying direction indicated by the arrow A in the figure and sends it to the medium conveying path.

The registration roller 30 corrects the skew of the recording medium sent out by the hopping roller 29 and further conveys the recording medium.
The transfer belt 32 conveys the recording medium P conveyed by the registration roller 30. The transfer belt 32 is an endless belt, and is rotatably stretched around the drive roller 33 and the idle roller 34.

The drive roller 33 is rotated by a drive source such as a motor to rotate the transfer belt 32.
The idle roller 34 is a driven roller that adjusts the tension of the transfer belt 32 to stabilize the rotation of the transfer belt 32.

The transfer roller 5 is disposed to face the photosensitive drum 1 via the transfer belt 32, and transfers the toner image formed on the photosensitive drum 1 to the recording medium P conveyed by the transfer belt 32.
The belt cleaning device 35 is for cleaning the toner on the transfer belt 32.

  The fixing device 13 is a device that is disposed downstream of the transfer belt 32 in the medium conveyance direction and fixes the toner image transferred onto the recording medium P by heating and pressing, and includes a heat roller 13a and a pressure roller 13b. And.

The heat roller 13a is provided with an elastic layer of silicone rubber on an iron base tube having an outer diameter of 28 mm, and a PFA tube as a toner peeling layer so as to cover the elastic layer. The heat roller 13a includes a halogen lamp as a heat source inside the element tube.
The pressure roller 13b has no elastic layer and is provided with a PFA tube on an iron base tube.
The discharge roller 31 discharges the recording medium conveyed from the fixing device 13 to the outside of the apparatus.

  The temperature / humidity sensor 36 detects the ambient temperature / humidity around the image forming apparatus 100, and is attached to a position that is not easily affected by the heat of the fixing device 13.

FIG. 2 is a block diagram showing a control configuration of the image forming apparatus in the first embodiment.
2, the image forming apparatus 100 includes a temperature / humidity sensor 36, a control unit 21, a drive control unit 38, a fixing control unit 25, an exposure control unit 26, a voltage control unit 27, a drum motor 39, The fixing device 13 includes an LED head 3, a charging roller 2, a developing roller 8, a supply roller 9, a regulating blade 10, and a transfer roller 5.

The control unit 21 includes control means such as a CPU (Central Processing Unit), and controls the operation of the entire image forming apparatus 100 based on a control program stored in the storage unit 40 such as a memory.
The control unit 21 includes a storage unit 40 and an image output unit 24.
The storage unit 40 stores the control program described above, control information necessary for controlling the operation of the image forming apparatus 100, and the like.

The image output unit 24 controls the drive control unit 38, the fixing control unit 25, the exposure control unit 26, and the voltage control unit 27 to generate a toner image on the recording medium with the developing units 12W, 12M, 12Y, and 12C shown in FIG. Printing to be formed is performed.
When control unit 21 receives print data instructing printing from a host computer as an external device connected to a communication line or the like, based on the temperature / humidity information detected by temperature / humidity sensor 36 and the print data received from the host computer. The image output unit 24 is instructed to print.

In addition, the control unit 21 controls printing speed (high speed, medium speed, or low speed) according to the type of medium, identifies and calculates a drum count, and determines whether high-speed idling described later is necessary.
Here, the drum count is the total number of rotations of the photosensitive drum 1, and is a value accumulated when the photosensitive drum 1 shown in FIG. For example, when three A4 size recording media are printed, the count increases by three.

The storage unit 40 stores a drum count and a counter value γ1, a counter value γ2, an X value, an addition value a, and an addition value b, which are control information described later.
The counter value γ1 and the counter value γ2 are counter values that are used when the control unit 21 determines whether high-speed idling is necessary. The counter value γ1 and the counter value γ2 are index values accumulated based on the drum count, and are indices indicating the rotation amount of the photosensitive drum 1 shown in FIG. 1 when the printing speed is low and medium.

  When receiving an instruction from the image output unit 24, the drive control unit 38 controls the rotation operation of the drum motor 39, and controls the rotation of the photosensitive drum 1 and the developing roller 8 shown in FIG. The drive control unit 38 changes the rotation speed of the drum motor 39 to a high speed, a medium speed, or a low speed in accordance with an instruction from the image output unit 24.

The exposure control unit 26 controls the light emission of the LED head 3 when receiving an instruction from the image output unit 24.
The voltage control unit 27 controls the voltage applied to the charging roller 2, the developing roller 8, the supply roller 9, the regulating blade 10, and the transfer roller 5 when receiving an instruction from the image output unit 24.

The fixing control unit 25 controls the temperature of the fixing device 13 upon receiving an instruction from the image output unit 24.
In this embodiment, the control unit 21 controls the rotation of the photosensitive drum 1 and the developing roller 8 shown in FIG. 1 by the image output unit 24 and the drive control unit 38, and an addition value (addition value a or Accumulated values (counter value γ1 and counter value γ2) obtained by accumulating the added value b) are calculated.

  Further, when the rotational speed of the developing roller 8 rotates at a rotational speed slower than a predetermined rotational speed, the control unit 21 rotates the developing roller 8 at high speed when the cumulative value (counter value γ2) reaches the threshold value X. Perform the action.

  The operation of the above configuration will be described.

First, a printing operation including an image forming process performed by the image forming apparatus will be described with reference to FIGS.
When receiving a printing instruction from the host computer, the control unit 21 of the image forming apparatus 100 starts a printing operation, instructs the image output unit 24 to print, and rotates the hopping roller 29 to be accommodated in the tray 28. The recording medium is conveyed to the developing units 12W, 12M, 12Y, and 12C.

  In response to the print instruction, the image output unit 24 controls the developing units 12W, 12M, 12Y, and 12C, and starts an image forming process. In the following description, the image output unit 24 controls the developing units 12W, 12M, 12Y, and 12C.

The image output unit 24 applies a charging voltage to the charging roller 2 by the voltage control unit 27 to uniformly charge the surface of the photosensitive drum 1.
After uniformly charging the surface of the photosensitive drum 1, the image output unit 24 causes the LED head 3 to emit light by the exposure control unit 26 to form an electrostatic latent image on the surface of the photosensitive drum 1.

  The image output unit 24 applies a developing voltage to the developing roller 8 having a thin toner layer formed on the surface thereof by the voltage control unit 27, and conveys the toner to the electrostatic latent image formed on the surface of the photosensitive drum 1. Then, the toner image is developed.

  At this time, the supply roller 9 and the regulating blade 10 are supplied by the voltage control unit 27 in order to uniformly form the toner thin layer on the developing roller 8 and to set the charge amount of the toner in the toner thin layer to a predetermined value. A voltage and a regulation voltage are respectively applied.

Next, the image output unit 24 applies a transfer voltage to the transfer roller 5 by the voltage control unit 27 to transfer the toner image on the photosensitive drum 1 to the recording medium P.
When the toner image is transferred to the recording medium P, the image output unit 24 fixes the toner image on the recording medium P by the fixing device 13 by the fixing control unit 25, and ends the image forming process.

The control unit 21 discharges the recording medium P on which the toner image is fixed to the outside of the apparatus by the discharge roller 31 and ends the printing operation.
Note that the toner remaining on the photosensitive drum 1 without being transferred is removed by the cleaning device 6.
Here, in this embodiment, it is assumed that the X value and the addition value as the control information shown in Table 1 are stored in the storage unit 40 in advance.

表１において、現像ローラ回転速度Ｖとは、現像ローラ８の周速度（周面の移動速度）であり、現像ローラ回転速度Ｖ≦９１ｍｍ／ｓ、９１ｍｍ／ｓ＜現像ローラ回転速度Ｖ＜１３１ｍｍ／ｓ、１３１ｍｍ／ｓ≦現像ローラ回転速度Ｖに分類されたものである。

In Table 1, the developing roller rotation speed V is the circumferential speed (moving speed of the peripheral surface) of the developing roller 8, and the developing roller rotation speed V ≦ 91 mm / s, 91 mm / s <developing roller rotation speed V <131 mm / s, 131 mm / s ≦ developing roller rotation speed V.

  The X value is a threshold value for determining whether high speed idling is necessary. In the present embodiment, when the counter value accumulated by the control unit 21 (counter value γ2 described later) becomes equal to or greater than the X value, the control unit 21 determines that high-speed idling is necessary.

The added value is a value to be added to the counter value when one sheet (page) of an A4 size recording medium is printed, and is a value determined according to the developing roller rotation speed V.
When the developing roller rotation speed V ≦ 91 mm / s, the added value is “a”, which is “9” in this embodiment.
When 91 mm / s <developing roller rotation speed V <131 mm / s, the added value is b, which is “1” in this embodiment.

The relationship between the addition values is a> b.
That is, when the first threshold value of the developing roller rotation speed V is 91 mm / s, the second threshold value is 131 mm / s, and the low-speed printing with the developing roller rotation speed V equal to or lower than the first threshold value is performed, the second addition value When the medium speed printing is performed with the developing roller rotation speed V larger than the first threshold value and less than the second threshold value, the first addition value b is determined. Note that when high-speed printing in which the developing roller rotation speed V is equal to or higher than the second threshold is performed, the addition value is 0 and the counter value is initialized (reset) to “0”.

Here, the counter value will be described.
The counter value is based on the drum count. When medium-speed printing is performed, the same added value as the drum count (“1” when printing one A4 size recording medium (page)) is added, and the counter value is low. When printing is performed, an addition value larger than the drum count (“9” when one A4 size recording medium (page) is printed) is added.

  That is, when the developing roller rotation speed V is faster than 91 mm / s and slower than 131 mm / s, the counter value is incremented by 1 when printing one A4 size recording medium (page), and from 91 mm / s. If it is slow, 9 is added when one A4 size recording medium is printed.

  Further, the counter value is performed when the developing units 12W, 12M, 12Y, and 12C shown in FIG. 1 are replaced, when the power is turned on, when the cover is opened, and when the normal mode is restored from the power saving mode. It is initialized to “0” in the initialization process of the image forming apparatus 100. Furthermore, when high-speed printing with the developing roller rotation speed V equal to or higher than the second threshold value is performed, it is initialized to “0”.

  Thus, the counter value of this embodiment is accumulated by adding a predetermined addition value corresponding to the developing roller rotation speed V. Further, the control unit 21 increases the added value as the developing roller rotation speed V becomes slower, and accumulates the added value in the counter value.

High-speed idling means applying the same voltage as during printing to count the two rollers at 200 mm / s, which is the fastest rotation speed among the rotation speeds at which the image forming apparatus 100 can rotate the developing roller 8 and the photosensitive drum 1. That is, the developing roller 8 and the photosensitive drum 1 are idled.
Note that the X value, the added value a, the added value b, the drum count in the high speed idling, and the fastest rotation speed described above are examples, and may be appropriately adjusted according to the characteristics of the image forming apparatus 100.

Further, when the printing failure depends on temperature and humidity, the detection result of the temperature and humidity sensor 36 is used to determine the X value, the added value a, the added value b, and the drum count in the high speed idling according to the temperature and humidity around the image forming apparatus 100. In addition, the fastest rotation speed may be adjusted.
Next, the idling control process performed by the image forming apparatus will be described with reference to FIG. 1 and FIG. 2 according to the step represented by S in the flowchart showing the idling control process flow in the first embodiment of FIG. .

  In this embodiment, for ease of explanation, one developing unit will be described as a processing target.

  The developing unit is a developing unit 12W shown in FIG. 1 that uses a white developer. This is because the white developer contains titanium oxide, and compared with other color developers, the white developer causes more damage to the surface of the supply roller, and wear powder on the supply roller is likely to be generated. Because. However, the developing unit that is the subject of this processing may be a developing unit that uses a developer other than white.

  The value γ1 is a counter value (cumulative value) for determining whether or not “high-speed idling” is necessary before starting printing, and the value γ2 is “high-speed idling after starting printing”. "Is a counter value (cumulative value) for determining whether or not to implement.

S101: The control unit 21 of the image forming apparatus 100 receives print data transmitted from an external apparatus (for example, a host computer such as a personal computer) serving as print data transmission means connected to the communication line.
In this embodiment, it is assumed that the control unit 21 of the image forming apparatus 100 receives print data including an instruction to print on an A4 size print medium. The print data includes information indicating the type of print medium and image quality.

  Note that the information indicating the type of print medium and the image quality may be stored in the storage unit 40 upon receiving a user input operation using an operation panel or the like.

  S102: The control unit 21 inputs temperature / humidity information detected by the temperature / humidity sensor 36 from the temperature / humidity sensor 36. In the present embodiment, the X value, the added value a, the added value b, the drum count in the high speed idling, and the fastest rotation speed are not adjusted based on the detected temperature and humidity information. Also good. For example, when the temperature is higher than the predetermined temperature and humidity, the addition value a is adjusted from 9 to 15, the addition value b is increased from 1 to 5, or the X value is adjusted to be small.

  S103: The control unit 21 determines the developing roller rotation speed V based on information indicating the type of recording medium and the image quality included in the print data, and processing is performed when the developing roller rotation speed V is 91 mm / s or less. When the developing roller rotation speed V is higher than 91 mm / s, the process proceeds to S107.

In the image forming apparatus 100 of this embodiment, when the information indicating the type of the recording medium is plain paper and thin paper (for example, the basis weight is 64 g / m ² or less), the image forming apparatus 100 is high speed (the developing roller rotation speed V is 131 mm / mm). s or more), plain paper and slightly thick paper (for example, basis weight of about 80 to 105 g / m ² ), medium speed (developing roller rotation speed V is faster than 91 and slower than 131 mm / s), plain paper In the case of thick paper (for example, the basis weight is 200 g / m ² or more) or film, printing is performed at a low printing speed (developing roller rotation speed V is 91 mm / s or less).

  Further, when the glossiness is high, the information representing the image quality is low (developing roller rotation speed V is 91 mm / s or less), and when the glossiness is low, the medium speed (developing roller rotation speed V is faster than 91, 131 mm / s). It is assumed that printing is performed at a printing speed slower than s.

  S104: When determining that the developing roller rotation speed V is 91 mm / s or less, the control unit 21 starts printing at the printing speed instructed by the print data.

  S105: The control unit 21 adds the addition value a to the counter value γ1 stored in the storage unit 40 and stores it in the storage unit 40 as the counter value γ2.

  S106: The control unit 21 finishes printing one page of the print data, and the process proceeds to S113.

  S107: The controller 21, which has determined that the developing roller rotation speed V is higher than 91 mm / s in S103, further determines the developing roller rotation speed V, the developing roller rotation speed V is higher than 91 mm / s, and from 131 mm / s. If it is slow, the process proceeds to S108, and if the developing roller rotation speed V is 131 mm / s or more, the process proceeds to S111.

  S108: When determining that the developing roller rotation speed V is faster than 91 mm / s and slower than 131 mm / s, the control unit 21 starts printing at the printing speed indicated by the print data.

  S109: The control unit 21 adds the addition value b to the counter value γ1 stored in the storage unit 40 and stores it in the storage unit 40 as the counter value γ2.

  S110: The control unit 21 finishes printing one page of print data, and the process proceeds to S113.

  S111: If the control unit 21 determines that the developing roller rotation speed V is 131 mm / s or more, the control unit 21 starts printing at a printing speed instructed by the print data.

  S112: The control unit 21 finishes printing one page of print data without adding the added value to the counter value γ1, and shifts the process to S115 to reset the counter value γ2.

  S113: The control unit 21 compares the counter value γ2 stored in the storage unit 40 with the X value, determines whether or not the counter value γ2 is equal to or greater than the X value, that is, whether or not high-speed idling is necessary. If it is determined that the value γ2 is greater than or equal to the X value, the process proceeds to S114 because high-speed idling is necessary. If it is determined that the counter value γ2 is less than the X value, the process proceeds to S116 because no high-speed idling is necessary. Transition.

  S114: If the control unit 21 determines that the counter value γ2 is equal to or greater than the X value (70 in this embodiment), that is, high-speed idling is necessary, the image output unit 24 causes the developing units 12W, 12M, and 12Y to , 12C high speed idling is executed. Here, when the print data prints a plurality of pages, the control unit 21 temporarily suspends the printing operation and executes high-speed idling.

S115: The control unit 21 resets the counter value γ2 stored in the storage unit 40 to “0”.
Here, the control unit 21 also resets the counter value γ2 stored in the storage unit 40 to “0” even when it is determined in S107 that the developing roller rotation speed V is 131 mm / s or more. This is because when printing is performed at a developing roller rotational speed V of 131 mm / s or more, the same effect as that obtained when idling is obtained.

  S116: The control unit 21 rewrites the counter value γ1 stored in the storage unit 40 to the counter value γ2. Therefore, the counter value γ1 is accumulated every time one page is printed.

S117: The control unit 21 determines whether or not printing of all pages of the print data has been completed. When it is determined that printing has ended, the process ends. When it is determined that there is still a page to be printed, the process proceeds to S102. The process described above is repeated.
Here, the occurrence of printing defects when high-speed idling is not performed will be described based on experimental results.

  Table 2 shows the relationship between the developing roller rotation speed V and the drum count until printing failure occurs.

表２に示すように、現像ローラ回転速度Ｖが９１ｍｍ／ｓ以下では、ドラムカウントが１０カウントで印刷不良が発生し、現像ローラ回転速度Ｖが９１ｍｍ／ｓより速く、かつ１３１ｍｍ／ｓより遅い場合では、ドラムカウントが８０カウントで印刷不良が発生している。なお、現像ローラ回転速度Ｖが１３１ｍｍ／ｓ以上の場合、印刷不良は発生しない。

As shown in Table 2, when the developing roller rotation speed V is 91 mm / s or less, printing failure occurs when the drum count is 10 counts, and the developing roller rotation speed V is faster than 91 mm / s and slower than 131 mm / s. In this case, printing failure occurs when the drum count is 80 counts. In addition, when the developing roller rotation speed V is 131 mm / s or more, printing failure does not occur.

  Next, Table 3 shows the relationship between the drum count and the developing roller rotation speed V until printing is performed using the developing unit in which the above-described printing failure occurs, and the printing failure disappears.

表３に示すように、現像ローラ回転速度Ｖが、１３１ｍｍ／ｓではドラムカウントが５カウント、１７１ｍｍ／ｓ以上ではドラムカウントが２カウントで印刷不良が消失した。
しかし、現像ローラ回転速度Ｖが９１ｍｍ／ｓ以下では、印刷不良が消失しなかった。

As shown in Table 3, when the developing roller rotation speed V is 131 mm / s, the drum count is 5 counts, and when the developing roller rotational speed V is 171 mm / s or more, the drum count is 2 counts and the printing defect disappears.
However, when the developing roller rotation speed V was 91 mm / s or less, the printing failure did not disappear.

  From the above, printing failure occurs when the developing roller rotation speed V is less than 131 mm / s, and is more likely to occur as the developing roller rotation speed V is slower.

  Further, when a printing failure occurs, the printing failure disappears if printing is performed at a developing roller rotation speed V of 131 mm / s or more.

  Further, the effect of eliminating the printing defect is greater as the developing roller rotation speed V is faster.

  The cause of this printing failure is that the contact between the developing roller 8 and the regulating blade 10 is clogged with foreign particles such as abrasion powder of the supply roller 9 shown in FIG.

  Accordingly, if the printing operation is performed at a developing roller rotation speed V of 131 mm / s or higher, foreign matter can pass through the regulating blade 10 due to its inertial force, and the contact between the developing roller 8 and the regulating blade 10 can be achieved. It is possible to prevent clogging with foreign substances.

  In the present embodiment, since the foreign matter causing the printing failure starts to accumulate at a timing near the contact portion between the developing roller 8 and the regulating blade 10, the foreign matter is removed from the developing roller 8 and the regulating blade. 10 can pass through the vicinity of the abutting portion, and clogging of foreign matter near the abutting portion can be suppressed, and the occurrence of printing defects can be suppressed.

  As described above, the control unit 21 of the image forming apparatus 100 continues printing with the developing roller rotation speed V slower than the predetermined rotation speed, and executes high-speed idling when the counter value based on the drum count reaches the threshold value. By doing so, clogging of foreign matter in the vicinity of the contact portion between the developing roller 8 and the regulating blade 10 can be suppressed, and the occurrence of printing defects can be suppressed.

  In addition, the control unit 21 can suppress a decrease in printing performance and an increase in useless drum count by suppressing the frequency of performing high-speed idling according to the developing roller rotation speed V to a necessary minimum. The life of the developing unit can be extended.

  In this embodiment, the developing unit to be processed (inspected) is described as one developing unit 12W, and accordingly, the X value and the counter values γ1 and γ2 are each one. However, there are a plurality of developing units. If present, the X value and the counter values γ1 and γ2 may be stored in the storage unit 40 so as to correspond to each developing unit, and individual values may be assigned to each. In that case, high speed idling is performed for each developing unit.

  Further, a set of X values and counter values γ1 and γ2 are made to correspond to the developing unit 12W that is likely to be clogged with foreign matter, and a set of X values and counters are set to the developing units 12M, 12Y, and 12C other than the developing unit 12W. The values γ1 and γ2 may be associated with each other, and the high-speed idling may be performed separately for the developing unit 12W and the developing units 12M, 12Y, and 12C.

  Furthermore, in this embodiment, the developing roller rotation speed V is classified into three stages, but it may be classified into two stages or four or more stages, and an additional value may be assigned to each.

  As described above, in the first embodiment, since the foreign matter causing the printing failure starts to accumulate near the contact portion between the developing roller and the regulating blade, the foreign matter is removed. It is possible to pass through the vicinity of the contact portion between the developing roller and the regulating blade, thereby suppressing the clogging of foreign matter in the vicinity of the contact portion and suppressing the occurrence of printing defects.

  In addition, by reducing the frequency of high-speed idling according to the rotation speed of the developing roller to the minimum necessary, it is possible to suppress a decrease in printing performance and an increase in unnecessary drum count, and a long life of the developing unit. The effect that it can achieve is obtained.

  Since the configuration of the second embodiment is the same as the configuration of the first embodiment, the same reference numerals are given and description thereof is omitted.

  The operation of the second embodiment will be described.

  Since the printing operation including the image forming process performed by the image forming apparatus is the same as that in the first embodiment, the description thereof is omitted.

  The idling control process performed by the image forming apparatus will be described with reference to FIGS. 1 and 2 in accordance with a step represented by S in the flowchart showing the idling control process flow in the second embodiment of FIG.

In this embodiment, S201 is added between S114 and S115 with respect to the flowchart of the idling control process in the first embodiment shown in FIG.
S101-S112: Since it is the same process as S101-S112 shown in FIG. 3, description is abbreviate | omitted.

Note that the control unit 21 that has started printing in S104, S108, and S111 cumulatively stores the drum count associated with the printing operation in the storage unit 40 during the printing operation.
The drum count accumulated and stored in the storage unit 40 is a cumulative value of the drum count after replacement with a new developing unit.

  S113: The control unit 21 compares the counter value γ2 stored in the storage unit 40 with the X value, determines whether or not the counter value γ2 is equal to or greater than the X value, that is, whether or not high-speed idling is necessary. If it is determined that the value γ2 is greater than or equal to the X value, the process proceeds to S201 because high speed idling is necessary, and if it is determined that the counter value γ2 is less than the X value, the process proceeds to S116 because no high speed idling is necessary. Transition.

  S201: The control unit 21 determines whether or not the drum count stored in the storage unit 40 is 5000 counts or more. If the control unit 21 determines that 5000 counts or more, that is, high-speed idling is necessary, the process proceeds to S114. If it is determined that it is less than 5000 counts, that is, high-speed idling is not required, the process proceeds to S116.

  Thus, in this embodiment, the control unit 21 suppresses the high-speed idling operation of the developing roller 8 until the drum count after the start of use of the developing unit reaches a predetermined value (5000 counts).

  S114 to S117: The processing is the same as S114 to S117 shown in FIG.

  Here, the reason why the high-speed idling is necessary when 5000 counts or more will be described with reference to Table 4.

表４に示すように、５台の画像形成装置を用いて連続印刷（１５５００ドラムカウント）の実験を行った結果、５台中３台が６０００カウントで印刷不良が発生し、かつ６０００カウントが最も小さいドラムカウントであった。なお、１台は１４３００カウントで印刷不良が発生し、１台は印刷不良が発生しなかった。

As shown in Table 4, as a result of conducting an experiment of continuous printing (15500 drum counts) using five image forming apparatuses, three of the five units had a printing defect of 6000 counts, and the 6000 count was the smallest. It was a drum count. One of the printers had a printing failure at 14300 counts, and one of the printers had no printing failure.

  This is considered that when a developing unit is used from a new one, the generation of foreign matter is small in the initial stage, and printing failure does not occur. In this embodiment, considering the margin, high speed idling is not necessary if the drum count is less than 5000 counts.

  In this embodiment, since the high-speed idling is not performed at the initial stage when the use of the developing unit is started, useless high-speed idling can be further suppressed as compared with the first embodiment. The life of the developing unit can be extended.

  As described above, the control unit 21 of the image forming apparatus 100 continues printing with the developing roller rotational speed V slower than the predetermined rotational speed, and the drum count accumulated in the storage unit 40 even when the drum count reaches the threshold value. If the threshold value does not reach the threshold value, high-speed idling is not performed, so that it is possible to suppress a decrease in printing performance and an unnecessary increase in drum count, and to extend the life of the developing unit. .

As described above, in the second embodiment, in addition to the effects of the first embodiment, it is possible to further suppress useless high-speed idling and to extend the life of the developing unit. can get.
In the first and second embodiments, the image forming apparatus is described as a printer. However, the image forming apparatus is not limited thereto, and may be a copier, a facsimile machine, or a multifunction peripheral (MFP).

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 LED head 4 Developing device 5 Transfer roller 6 Cleaning device 8 Developing roller 9 Supply roller 10 Control blade 12W, 12M, 12Y, 12C Developing unit 13 Fixing device 21 Control unit 25 Fixing control unit 26 Exposure control unit DESCRIPTION OF SYMBOLS 27 Voltage control part 28 Tray 29 Hopping roller 30 Registration roller 31 Discharge roller 32 Transfer belt 33 Drive roller 34 Idle roller 35 Belt cleaning apparatus 36 Temperature / humidity sensor 38 Drive control part 39 Drum motor 40 Memory | storage part 100 Image forming apparatus

Claims (11)

A rotatable image carrier;
A rotatable developer carrier that supplies the image carrier with developer regulated by a regulating member;
A controller that controls rotation of the image carrier and the developer carrier, and calculates a cumulative value obtained by accumulating an addition value based on the rotation;
Have
The controller is
In the case where the rotation speed of the developer carrier is rotated at a rotation speed lower than a predetermined rotation speed, the developer carrier is idled when the accumulated value reaches a threshold value. Forming equipment. The image forming apparatus according to claim 1.
The accumulated value is accumulated by adding a predetermined addition value according to the rotation speed of the developer carrier,
The controller is
The image forming apparatus, wherein the added value is increased as the rotation speed of the developer carrying member is decreased. The image forming apparatus according to claim 2.
The predetermined addition value is determined by a rotation speed of the developer carrying member, a first threshold value, and a second threshold value greater than the first threshold value,
The controller is
When the rotation speed of the developer carrier is larger than the first threshold and smaller than the second threshold, a first addition value is added to the accumulated value,
2. An image forming apparatus according to claim 1, wherein when the rotation speed of the developer carrying member is equal to or lower than the first threshold value, a second added value larger than the first added value is added to the accumulated value. The image forming apparatus according to claim 3.
The image forming apparatus, wherein the accumulated value is initialized to 0 when the rotation speed of the developer carrying member is equal to or higher than the second threshold value. The image forming apparatus according to claim 3 or 4, wherein:
The rotational speed of the developer carrier is a peripheral speed of the developer carrier,
The first threshold value is 91 mm / s,
The image forming apparatus, wherein the second threshold value is 131 mm / s. The image forming apparatus according to claim 1, wherein:
The controller is
An image forming apparatus that performs the idling operation of rotating the developer carrier at the fastest rotation speed among the possible rotation speeds of the developer carrier. The image forming apparatus according to any one of claims 1 to 6,
The accumulated value is a value accumulated based on the total number of rotations of the image carrier. The image forming apparatus according to any one of claims 1 to 7,
The controller is
An image forming apparatus characterized in that the idling operation of the developer carrier is suppressed until the total number of rotations of the image carrier after the start of use of the image carrier reaches a predetermined value. The image forming apparatus according to any one of claims 1 to 8,
It has a temperature and humidity detector that detects the temperature and humidity inside the device.
The controller is
The image forming apparatus, wherein the added value or the threshold value is changed based on the temperature and humidity detected by the temperature and humidity detection unit. The image forming apparatus according to any one of claims 1 to 9,
The controller is
An image forming apparatus, wherein a printing operation is interrupted when the idling operation is performed. The image forming apparatus according to any one of claims 1 to 10,
The image forming apparatus according to claim 1, wherein the regulating member is a regulating blade that contacts the developer carrying member and regulates the developer.

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