JP6127732B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Conventionally, in an electrophotographic image forming apparatus, a cleaning blade or the like is slidably brought into contact with the surface of an image carrier (for example, a photosensitive drum or an intermediate transfer member) on which a toner image is formed. Removal (cleaning) of deposits such as residual toner deposited on the surface is performed.

  When the image carrier is cleaned, a technique of applying and attaching a lubricant to the image carrier is used in order to reduce the adhesion force of the toner and improve the cleaning performance. Usually, the lubricant is applied to the image carrier through a brush member in which brush fibers are implanted. The brush member is installed in contact with the lubricant and the image carrier, scrapes the lubricant by coming into contact with the lubricant, and then applies the scraped lubricant to the surface of the image carrier.

Since the brush member is in contact with the image carrier while rotating, the rotational fluctuation caused by the brush member propagates to the image carrier and causes rotation unevenness in the image carrier. As a result, color misregistration and pitch unevenness occur, and the quality of the formed image decreases.
Therefore, a configuration is disclosed in which one cycle operation time of the photosensitive member peripheral member is set to 1 / integer of the movement time between exposure and transfer of the photosensitive member in order to suppress the occurrence of color misregistration and pitch unevenness (for example, Patent Document 1).

JP 2006-251523 A

  However, in the configuration described in Patent Document 1, there is no description about the definition of the speed range of the photosensitive member peripheral member and the control when the speed is variable, and the case where the speed is changed over time according to the conditions such as the number of printed sheets. In addition, there is a possibility that the speed of the load sensitivity is high. When the speed with high load sensitivity is reached, there is a problem in that color misregistration and pitch unevenness increase and the quality of the formed image decreases.

  The present invention is an image forming apparatus capable of suppressing the occurrence of color misregistration and pitch unevenness caused by a brush member even when the rotation speed is changed over time and ensuring the quality of an image to be formed with high accuracy. The purpose is to provide.

The invention described in claim 1 has been made to achieve the above object,
In the image forming apparatus,
A rotating body having an image carrying function;
An exposure unit that exposes the rotating body to form an electrostatic latent image on the rotating body;
A developing unit for developing the electrostatic latent image formed on the rotating body with a developer;
A transfer unit that transfers the image developed on the rotating body to a transfer target;
A brush member installed so as to contact the rotating body and applying a lubricant to the surface of the rotating body;
A control unit that performs control to change the rotation period of the brush member under a predetermined condition,
The controller is
When the rotation period of the brush member is T1, the rotation period of the rotating body is T2, the center angle between the exposure position by the exposure unit and the transfer position by the transfer unit in the rotating body is α, and the natural number is N,
Formula (1): T2 × α / 360 ° × 1 / N × 9/10 ≦ T1 ≦ T2 × α / 360 ° × 1 / N × 11/10
Controlling the rotation period of the brush member under the condition satisfying the formula (1) ,
Wherein the rotating body exposure position or the transfer position and said movable der Rukoto.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
N ≦ 3.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect ,
A mirror for moving the exposure position is provided.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect ,
A mirror control unit for moving the mirror back and forth is provided.

According to a fifth aspect of the present invention, in the image forming apparatus according to the third aspect ,
A mirror control unit for controlling the tilt of the mirror is provided.

The invention described in claim 6 is the image forming apparatus according to claim 1 or 2 ,
A plurality of the exposure units are provided,
The exposure positions of the plurality of exposure units are different from each other.

The invention according to claim 7 is the image forming apparatus according to claim 1 or 2 ,
The transfer unit is movable.

The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 7 ,
The controller changes the rotation cycle of the brush member based on a predetermined number of prints, the number of rotations or the rotational movement distance of the brush member, or the number of rotations or the rotational movement distance of the rotating body. Features.

The invention according to claim 9 is the image forming apparatus according to any one of claims 1 to 8 ,
An elastic member that presses the lubricant against the brush member is provided.

The invention according to claim 1 0, in the image forming apparatus according to any one of claims 1 to 9
The rotating body is a photosensitive drum.

The invention of claim 1 1, in the image forming apparatus according to any one of claims 1 to 1 0,
The control unit controls a motor that rotates the brush member.

  According to the present invention, even when the rotation speed is changed with time, the occurrence of color misregistration and pitch unevenness due to the brush member can be suppressed. Thereby, the quality of the formed image can be ensured with high accuracy.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. FIG. 2 is a diagram illustrating a schematic configuration of an image forming unit according to the present embodiment. FIG. 3 is a functional block diagram illustrating a control structure of the image forming apparatus according to the present embodiment. It is a figure which shows the simulation result about the speed fluctuation | variation and position shift of a photosensitive drum when the center angle of an exposure position and a transfer position is 180 degrees. It is a figure which shows the simulation result about the speed fluctuation | variation and position shift of a photoconductor drum when the center angle of an exposure position and a transfer position is 135 degrees. It is a figure which shows the actual machine measurement result about position shift of a photoconductive drum. It is a figure which shows the influence degree to the photoconductive drum which the rotation speed of a brush exerts. It is a figure which shows the relationship between the natural number N and lubricant consumption. FIG. 10 is a diagram illustrating a schematic configuration of an image forming unit according to a first modification. It is a figure which shows the amplification factor of the rotation speed of a brush. FIG. 10 is a diagram illustrating a schematic configuration of an image forming unit according to a second modification.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  The image forming apparatus 10 according to the present embodiment is used as, for example, a printer or a digital copying machine. As illustrated in FIGS. 1 to 3, the automatic document conveying unit 20, the scanner unit 30, the image forming unit 40, and a paper feed It comprises the part 50, the control part 1, etc.

  The automatic document transport unit 20 includes a placement tray on which the document D is placed, a mechanism for transporting the document D, a transport roller, and the like, and transports the document D to a predetermined transport path.

  The scanner unit 30 includes an optical system such as a light source and a reflecting mirror. The scanner unit 30 irradiates the document D conveyed on a predetermined conveyance path or the document D placed on the platen glass, and receives reflected light. . The scanner unit 30 converts the received reflected light into an electrical signal and outputs the electrical signal to the control unit 1.

The image forming unit 40 includes a yellow image forming unit Y, a magenta image forming unit M, a cyan image forming unit C, a black image forming unit K, an intermediate transfer member T, a fixing device F, and the like.
Each image forming unit YMCK forms yellow, magenta, cyan, and black toner images on the photosensitive drum, and transfers the YMCK toner images formed on the photosensitive drum to the intermediate transfer body T (primary transfer). .
Since the configuration and operation of each image forming unit YMCK are the same, a series of image forming operations performed by the image forming unit 40 will be described below taking the yellow image forming unit Y as an example.

  The yellow image forming unit Y includes a photosensitive drum 41, a charging device 42, an exposure device 43, a developing device 44, a primary transfer roller 45, a secondary transfer roller 46, a cleaning device 47, and the like.

  The photoconductor drum 41 has a drum shape, and the surface is formed of a photoconductor layer including an organic semiconductor layer in which a phthalocyanine pigment is dispersed in polycarbonate and a charge transport layer. The photosensitive drum 41 functions as a rotating body having an image carrying function.

The charging device 42 uniformly charges the photosensitive drum 41.
The exposure device (exposure unit) 43 exposes the non-image area of the photoconductive drum 41 based on the image data Dy from the control unit 1 to remove the charge of the exposed portion, and An electrostatic latent image is formed.

  The developing device (developing unit) 44 supplies toner as a developer onto the electrostatic latent image formed on the photosensitive drum 41, and forms a yellow toner image on the photosensitive drum 41.

The primary transfer roller (transfer section) 45 transfers the yellow toner image formed on the photosensitive drum 41 to the intermediate transfer body (transfer target body) T (primary transfer).
The other image forming units MCK similarly transfer magenta, cyan, and black toner images to the intermediate transfer member T. As a result, a color toner image of each color of YMCK is formed on the intermediate transfer member T.

  The secondary transfer roller 46 transfers the YMCK color toner images formed by being transferred to the intermediate transfer member T onto the paper P conveyed from the paper supply unit 50 (secondary transfer).

The image forming unit 40 heats and pressurizes the sheet P on which the toner images of each color of YMCK are secondarily transferred by the fixing device F, and then discharges the sheet P to the outside through a predetermined conveyance path.
The above is a series of image forming operations by the image forming unit 40.

The cleaning device 47 removes residues such as residual toner and paper dust remaining on the surface of the photosensitive drum 41 after the primary transfer. Further, the cleaning device 48 removes the residue remaining on the intermediate transfer member T after the secondary transfer.
The cleaning device 47 and the cleaning device 48 are the same in that they remove the residue remaining on the image carrier (photosensitive drum 41 or intermediate transfer member T), and perform the same configuration and operation.
Hereinafter, the configuration and operation will be described by taking the cleaning device 47 as an example.

  As shown in FIG. 2, the cleaning device 47 includes a blade 471, a brush 472, and a lubricant application device 473.

  The blade 471 is made of an elastic member such as silicon rubber or urethane rubber, and is installed so as to be in pressure contact with the rotation direction of the photosensitive drum 41 from the counter direction. The pressure contact here refers to a state of contact in a state where a load is applied. Further, the blade 471 peels off the residue remaining on the photosensitive drum 41.

  The brush 472 includes a rotation shaft and a plurality of brush bristles planted on the rotation shaft, and is installed to rotate in the forward direction with respect to the rotation direction of the photosensitive drum 41 and to rub against the photosensitive drum 41. . Further, the brush 472 scrapes the residue remaining on the surface of the photosensitive drum 41 with the brush hair, and applies the lubricant LO attached to the brush hair to the surface of the photosensitive drum 41. In other words, the brush 472 is installed in contact with the photosensitive drum 41 and the lubricant LO, and rotates to scrape off the lubricant LO and apply the scraped lubricant LO to the surface of the photosensitive drum 41. Function as.

The lubricant application device 473 includes a solid lubricant LO, a spring (elastic member) SP, and the like. The lubricant LO is installed so as to contact the brush 472, and the spring SP is installed so as to press the lubricant LO against the brush 472. The lubricant application device 473 presses the lubricant LO against the brush 472 by the force that the spring SP pushes up, and adheres the lubricant LO to the brush bristles.
For example, stearic acid zinc is used as the lubricant LO. When the lubricant LO is applied to the surface of the photosensitive drum 41 via the brush 472, the physical adhesion between the residue and the photosensitive drum 41 becomes weak, and the blade 471 can easily remove the residue.

  The paper feed unit 50 includes a plurality of trays, and each tray stores a plurality of different types of paper P. The paper feeding unit 50 feeds the paper P accommodated by a predetermined conveyance path to the image forming unit 40.

  The control unit 1 includes a CPU, a RAM, a ROM, and the like. The CPU expands various programs stored in the ROM to the RAM, and cooperates with the expanded various programs to perform the automatic document conveyance unit 20, The operation of each unit of the image forming apparatus 10 such as the scanner unit 30, the image forming unit 40, the paper feeding unit 50, etc. is comprehensively controlled (see FIG. 3). For example, the control unit 1 inputs an electric signal from the scanner unit 30 and performs various image processing, and outputs the image data Dy, Dm, Dc, and Dk of each color of YMCK generated by the image processing to the image forming unit 40. . The control unit 1 controls the operation of the image forming unit 40 to form an image on the paper P.

Further, the control unit 1 controls the rotation cycle of the brush 472. Specifically, the control unit 1 determines the rotation period of the brush 472 as “the rotation period of the photosensitive drum 41”, “the exposure position A 1 by the exposure device 43 on the photosensitive drum 41, and the transfer position A 2 by the primary transfer roller 45. Is controlled by a value obtained by multiplying the “center angle α / 360 °” and “1 / natural number N” (hereinafter referred to as a cycle Cy). In particular, the control unit 1 controls the rotation period of the brush 472 within ± 1/10 period of the period Cy. This is because the rotational speed of the photosensitive drum 41 at the exposure position A1 and the transfer position A2 can be made equal by controlling the rotational period of the brush 472 with the period Cy, and color misregistration and pitch unevenness caused by the brush 472 are caused. It is because generation | occurrence | production of this can be suppressed.
Further, the control unit 1 controls the number of rotations of the brush 472. Specifically, the control unit 1 controls the rotation number of the brush 472 with a natural number N ≦ 3. This is because by controlling the natural number N ≦ 3, it is possible to suppress an increase in lubricant consumption accompanying the excessive increase in the number of rotations of the brush 472.
Further, the control unit 1 changes the rotation period of the brush 472 based on the predetermined number of prints, the number of rotations or the rotational movement distance of the brush 472, or the number of rotations or the rotational movement distance of the photosensitive drum 41. That is, the control unit 1 changes the rotation period of the brush 472 over time according to changes in conditions such as the number of prints, the number of rotations or the rotation distance of the brush 472, or the number of rotations or the rotation distance of the photosensitive drum 41. Let For example, the control unit 1 increases the rotation period of the brush 472 when the number of printed sheets exceeds a specified number. As for the correspondence between the number of prints and the rotation period of the brush 472, a table defined for the correspondence is set in advance and stored in a ROM or the like. In addition, the control unit 1 increases the rotation period of the brush 472 when the number of rotations of the brush 472 exceeds a specified number. As for the correspondence between the number of rotations of the brush 472 and the rotation period of the brush 472, a table that defines the correspondence is set in advance and stored in a ROM or the like. That is, by identifying the decrease in the lubricant LO by the number of prints and the number of rotations of the brush 472, the rotation period of the brush 472 can be changed in accordance with the decrease in the lubricant LO.
In addition, the control unit 1 controls a motor (not shown) that rotates the brush 472. That is, the control unit 1 controls the number of rotations of the brush 472 and the rotation period of the brush 472 by controlling the motor.

  Hereinafter, the rotation cycle control process of the brush 472 in the image forming apparatus 10 according to the present embodiment will be described with reference to FIGS.

In this embodiment, as shown in FIGS. 1 and 2, the photosensitive drum 41 charged by the charging device 42 is exposed at the exposure position A1 by the exposure device 43, developed by the developing device 44, and the primary transfer roller. 45 is transferred to the intermediate transfer member T at the transfer position A2. At this time, if a difference occurs in the rotation speed of the photosensitive drum 41 between the exposure position A1 and the transfer position A2, toner images having different pitches are transferred onto the intermediate transfer body T, and appear on the image as color misregistration or pitch unevenness. .
One of the causes of the difference in the rotational speed of the photosensitive drum 41 between the exposure position A1 and the transfer position A2 is the brush 472. Since the brush 472 rotates while being in contact with the photoconductive drum 41, a rotation variation caused by the brush 472 is propagated to the photoconductive drum 41, thereby causing uneven rotation of the photoconductive drum 41. As a result, a difference occurs in the rotation speed of the photosensitive drum 41 between the exposure position A1 and the transfer position A2.
Therefore, in this embodiment, the photosensitive drum at the exposure position A1 and the transfer position A2 is controlled by controlling the rotation cycle of the brush 472 with the cycle Cy in order to suppress the occurrence of color misregistration and pitch unevenness caused by the brush 472. The rotational speed of 41 can be made equal.

FIG. 4 shows a simulation result of the speed fluctuation (FIG. 4A) and the positional deviation (FIG. 4B) of the photosensitive drum 41 when the center angle α between the exposure position A1 and the transfer position A2 is 180 °. Indicates.
Specifically, the rotation period of the photosensitive drum 41 is set to 1 [s], the center angle α between the exposure position A1 and the transfer position A2 is set to 180 °, and the rotation fluctuation of the brush 472 is set as noise, and the photosensitive drum 41 is set. The speed fluctuation and position deviation of were extracted. In addition, the noise component caused by the brush 472 is 3 in which the amplitude is 0.2% of the reference speed, the rotation period is 1/2 [s], 1/3 [s], and 1 / 5.5 [s]. Kind. The yellow Y graph shown in FIG. 4 is a 1/2 [s] periodic component, the magenta M graph is a 1/3 [s] periodic component, and the cyan C graph is a 1 / 5.5 [s] periodic component. The time difference between exposure and transfer is 1 [s] × 180 ° / 360 ° = 1/2 [s], and the difference in speed fluctuation of the photosensitive drum 41 at that time difference is converted as a positional deviation. As a result, as shown in FIG. 4B, the positional deviation of the cycle component of yellow Y in which the time difference between exposure and transfer coincides with the rotation cycle becomes zero. On the other hand, since the periodic components of magenta M and cyan C do not coincide with the time difference between exposure and transfer, a positional deviation occurs.

FIG. 5 shows a simulation result of the speed fluctuation (FIG. 5A) and the positional deviation (FIG. 5B) of the photosensitive drum 41 when the center angle α between the exposure position A1 and the transfer position A2 is 135 °. Indicates.
In the example shown in FIG. 5, the noise component caused by the brush 472 has a rotation period of 1/2 [s] for the yellow Y graph and 1 / 2.67 [s] for the magenta M graph. The cyan C graph is a 1/4 [s] periodic component. The time difference between exposure and transfer is 1 [s] × 135 ° / 360 ° = 1 / 2.67 [s]. As a result, as shown in FIG. 5B, the positional deviation of the period component of magenta M, in which the time difference between exposure and transfer and the rotation period coincide, becomes zero.

  From the results of FIGS. 4 and 5, the rotation cycle of the brush 472 is the cycle Cy, that is, “the rotation cycle of the photosensitive drum 41”, “the central angle α / 360 ° between the exposure position and the transfer position”, and “1 / natural number”. It can be seen that the rotation speed of the photosensitive drum 41 at the exposure position A1 and the transfer position A2 can be made equal by controlling the value by multiplying N (N = 1 in FIGS. 4 and 5) ”.

FIG. 6 shows an actual measurement result of the positional deviation of the photosensitive drum 41.
In the example shown in FIG. 6, in the actual machine measurement, the rotation period of the brush 472 is “when controlled by the period Cy (FIG. 6B)” and “other than that (FIG. 6A)” The displacement was compared. The positional deviation was derived by integrating speed data of encoders provided on the shafts of the photosensitive drums 41 of the YMCKs. Here, if the ratio of the linear velocity of the brush 472 to the linear velocity of the photosensitive drum 41 is θ, the rotational speed of the brush 472 when controlled by the cycle Cy is θ = 67%. On the other hand, as an example in other cases, FIG. 6A shows a measurement result when the rotation number of the brush 472 is θ = 86%. Note that the only difference between the case of FIG. 6A and the case of FIG. 6B is the rotation speed of the brush 472, and the other conditions are the same.
As a result, as shown in FIG. 6B, it was found that significant displacement can be suppressed when the rotation period of the brush 472 is “controlled by the period Cy”. Incidentally, the reason why the misalignment remains even in the case of FIG. 6B is due to noise due to rotational fluctuation of members other than the brush 472.

FIG. 7 shows the degree of influence of the rotation number of the brush 472 on the photosensitive drum 41.
In FIG. 7, the horizontal axis represents the rotation period of the brush 472, and the vertical axis represents the degree of influence on the photosensitive drum 41 (load sensitivity gain on the photosensitive drum 41 axis). Here, the load sensitivity gain is an amplitude change rate of the output vibration amplitude with respect to the input vibration amplitude. In this embodiment, the contribution ratio of the rotational fluctuation component (input) of the brush 472 to the rotational fluctuation component (output) of the photosensitive drum 41 axis is shown. That is, the photosensitive drum 41 is more affected by the rotational fluctuation component of the brush 472 as the value on the vertical axis increases.

表１に示されるように、負荷感度ゲインが０．５を超えると、画像の品質が許容できなくなることがわかる。 Table 1 shows the relationship between the load sensitivity gain and the image quality tolerance. In Table 1, “◎” indicates that the image quality is very good. In Table 1, “◯” indicates that the image quality is good. On the other hand, Δ in Table 1 indicates that the image quality is deteriorated due to the influence of color misregistration or the like. Further, the crosses in Table 1 indicate that the image quality is extremely deteriorated due to the influence of color misregistration and the like.

As shown in Table 1, it can be seen that when the load sensitivity gain exceeds 0.5, the image quality becomes unacceptable.

In the example illustrated in FIG. 7, the case where the rotation period (reference value) of the brush 472 in the case of “controlled by the period Cy” is 0.136 [s] is illustrated, and the rotation period is 0.136 [s]. In this case, the load sensitivity gain is zero. As shown in FIG. 7, if the control is performed within ± 1/10 period of the period Cy, the load sensitivity gain does not become 0.5 or more which is the threshold value.
Therefore, in this embodiment, the rotation period of the brush 472 is controlled within ± 1/10 period of the period Cy. That is, the control unit 1 sets the rotation period of the brush 472 to T1, the rotation period of the photosensitive drum 41 to T2, and the center angle between the exposure position A1 by the exposure device 43 and the transfer position A2 by the primary transfer roller 45 on the photosensitive drum 41. Is a and the natural number is N, the rotation period of the brush 472 is controlled under the condition satisfying the following expression (1).
Formula (1): T2 × α / 360 ° × 1 / N × 9/10 ≦ T1 ≦ T2 × α / 360 ° × 1 / N × 11/10

表２に示されるように、クリーニング性能を満足するためには、潤滑剤消費量が０．９６［ｇ／１００ｋｒｏｔ感光体］以上必要である。一方、潤滑剤ＬＯの耐久性を満足させるためには、潤滑剤消費量が１．３４［ｇ／１００ｋｒｏｔ感光体］以下であることが必要である。従って、潤滑剤消費量は、０．９６〜１．３４［ｇ／１００ｋｒｏｔ感光体］の範囲に収まることが好ましいことがわかる。
図８に示すように、自然数Ｎ＝１〜３の場合は、潤滑剤消費量が０．９６〜１．３４［ｇ／１００ｋｒｏｔ感光体］の範囲に収まるが、Ｎ≧４の場合は、ブラシ４７２の回転数が増加して潤滑剤消費量が増加し、短耐久となる。
従って、本実施形態では、ブラシ４７２の回転数を、自然数Ｎ≦３で制御するようにしている。 FIG. 8 shows the relationship between the natural number N and the lubricant consumption.
In FIG. 8, the horizontal axis represents the natural number N, and the vertical axis represents the lubricant consumption. The unit of the vertical axis (g / 100 krot photoconductor) indicates the consumption amount of the lubricant LO when the photoconductor drum 41 rotates 100 k. In the present embodiment, as the natural number N increases, the rotation period [s] of the brush 472 becomes shorter, so the rotation number of the brush 472 increases. As the number of rotations of the brush 472 increases, the amount of lubricant LO applied to the photosensitive drum 41 increases.
Table 2 shows the relationship between the lubricant consumption, the cleaning performance, and the durability of the lubricant LO. In Table 2, “◎” indicates that the cleaning performance or the durability of the lubricant LO is very good. In Table 2, ◯ indicates that the cleaning performance or the durability of the lubricant LO is good. On the other hand, Δ in Table 2 indicates that the cleaning performance or the durability of the lubricant LO is unsatisfactory. In Table 2, “X” indicates that the cleaning performance or the durability of the lubricant LO is extremely poor.

As shown in Table 2, in order to satisfy the cleaning performance, the amount of lubricant consumed must be 0.96 [g / 100 krot photoreceptor] or more. On the other hand, in order to satisfy the durability of the lubricant LO, it is necessary that the lubricant consumption is 1.34 [g / 100 krot photoreceptor] or less. Therefore, it can be seen that the lubricant consumption is preferably in the range of 0.96 to 1.34 [g / 100 krot photoreceptor].
As shown in FIG. 8, when the natural number N = 1-3, the lubricant consumption is within the range of 0.96-1.34 [g / 100 krot photoreceptor], but when N ≧ 4, the brush consumption The rotational speed of 472 increases, the amount of lubricant consumption increases, and the durability becomes short.
Therefore, in this embodiment, the rotation number of the brush 472 is controlled by a natural number N ≦ 3.

As described above, the image forming apparatus 10 of the present embodiment includes the photosensitive drum 41 having an image carrying function and the exposure device 43 that exposes the photosensitive drum 41 to form an electrostatic latent image on the photosensitive drum 41. A developing device 44 that develops the electrostatic latent image formed on the photosensitive drum 41 with toner, a primary transfer roller 45 that transfers the image developed on the photosensitive drum 41 to the intermediate transfer member T, and a photosensitive drum. And a brush 472 for applying the lubricant LO to the surface of the photosensitive drum 41, and a controller 1 for performing control to change the rotation period of the brush 472 under a predetermined condition. Further, the control unit 1 sets the rotation cycle of the brush 472 to T1, the rotation cycle of the photosensitive drum 41 to T2, and the center angle between the exposure position A1 by the exposure device 43 and the transfer position A2 by the primary transfer roller 45 on the photosensitive drum 41. Is a and the natural number is N, the rotation period of the brush 472 is controlled under the condition satisfying the following expression (1).
Formula (1): T2 × α / 360 ° × 1 / N × 9/10 ≦ T1 ≦ T2 × α / 360 ° × 1 / N × 11/10
Therefore, according to the image forming apparatus 10 of the present embodiment, the rotational speed of the photosensitive drum 41 at the exposure position A1 and the transfer position A2 can be made equal even when the rotational speed is changed over time. The occurrence of color misregistration and pitch unevenness due to 472 can be significantly suppressed. Thereby, the quality of the formed image can be ensured with high accuracy.

  Further, according to the image forming apparatus 10 of the present embodiment, since the natural number N ≦ 3, it is possible to suppress an increase in lubricant consumption due to an excessive increase in the number of rotations of the brush 472. Thereby, both the cleaning performance and the durability of the lubricant LO can be satisfied, and the working time and cost associated with the replacement of the lubricant LO can be reduced.

  As mentioned above, although concretely demonstrated based on embodiment which concerns on this invention, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.

(Modification 1)
For example, the example shown in FIG. 9 differs from the embodiment in that the exposure position A1 by the exposure device 43 can be moved. For simplification of description, the same reference numerals are given to the same configurations as those in the embodiment, and detailed description thereof is omitted.

The brush 472 may amplify the rotational speed over time in order not to deteriorate the cleaning performance. When the rotation cycle of the brush 472 is controlled by the cycle Cy, the rotation number of the brush 472 is amplified at a speed N times the natural number by increasing the value of the natural number N. Here, when the amplification factor of the rotation number of the brush 472 is large, the amount of the lubricant LO that enters the developing device 44 increases instantaneously, so that there is a possibility of developing unevenness.
Therefore, in the first modification, the exposure position A1 is made movable to control the time difference between exposure and transfer.

Specifically, as illustrated in FIG. 9, the image forming apparatus 10 according to the first modification includes a mirror 61 that reflects the beam L emitted from the exposure device 43 toward the photosensitive drum 41, and the mirror 61 is moved back and forth. An actuator (mirror controller) 62 to be operated.
The controller 1 controls the actuator 62 to move the position of the mirror 61 forward and backward. When the control unit 1 is disposed at a position where the mirror 61 is retracted, the beam L and the mirror 61 do not contact each other, and the exposure position is normal A1. On the other hand, when the control unit 1 places the mirror 61 in the advanced position, the beam L is reflected by the mirror 61 and the exposure position moves to B1.
The sequence for amplifying the rotation speed of the brush 472 is a natural number N = 1 (mirror 61 retracted) → N = 1 (mirror 61 advanced) → N = 2 (mirror 61 retracted) → N = 2 (mirror 61 advanced) → N = 3 (mirror 61 retracted) → N = 3 (mirror 61 advanced).
As shown in FIG. 10, when the rotation speed of the brush 472 is controlled in the above sequence (G2 in the figure), the rotation speed is higher than when the rotation speed of the brush 472 is amplified at a natural number N times (G1 in the figure). The amplification factor of the number can be reduced.

  As described above, according to the image forming apparatus 10 of the first modification, the exposure position A1 on the photosensitive drum 41 can be moved, so that the amplification factor of the rotation number of the brush 472 can be reduced. Therefore, the amount of the lubricant LO that enters the developing device 44 does not increase instantaneously, and the occurrence of uneven development can be suppressed.

  In the first modification, the position of the mirror 61 is moved forward and backward by the actuator 62 to move the exposure position A1, but the present invention is not limited to this. For example, the exposure position A1 may be moved by changing the tilt of the mirror 61 by the actuator 62. That is, during normal operation, the tilt of the mirror 61 is controlled so that the angle does not come into contact with the beam L emitted by the exposure device 43, and the tilt of the mirror 61 is brought into contact with the beam L when the exposure position A1 is moved. You may make it control so that it may become an angle to do.

  Further, instead of providing the mirror 61, a plurality of exposure devices 43 may be provided. In this case, different exposure positions may be set to be exposed for each exposure apparatus 43, and the exposure apparatus 43 (exposure position) may be selected in accordance with a sequence for amplifying the number of rotations of the brush 472.

(Modification 2)
Further, the example shown in FIG. 11 is different from the embodiment in that the transfer position A2 by the primary transfer roller 45 can be moved. For simplification of description, the same reference numerals are given to the same configurations as those in the embodiment, and detailed description thereof is omitted.

In the second modification, unlike the first modification, the transfer position A2 can be moved to control the time difference between exposure and transfer.
Specifically, the image forming apparatus 10 according to Modification 2 includes a cam (not shown) that swings the primary transfer roller 45 up and down.
The control unit 1 controls the cam and the like to swing the primary transfer roller 45 up and down. That is, when moving the transfer position A2, the control unit 1 swings the primary transfer roller 45 upward from the normal transfer position A2 and arranges it at the transfer position B2.
The sequence for amplifying the rotational speed of the brush 472 is a natural number N = 1 (the primary transfer roller 45 is disposed at a normal position) → N = 1 (the primary transfer roller 45 is swung upward) → N = 2 (the primary transfer roller) 45 is arranged at the normal position) → N = 2 (the primary transfer roller 45 is swung upward) → N = 3 (the primary transfer roller 45 is arranged at the normal position) → N = 3 (the primary transfer roller 45 is moved upward) Rocking).
As shown in FIG. 10, when the rotation speed of the brush 472 is controlled in the above sequence (G2 in the figure), the rotation speed is higher than when the rotation speed of the brush 472 is amplified at a natural number N times (G1 in the figure). The amplification factor of the number can be reduced.

  As described above, according to the image forming apparatus 10 of the second modification, the transfer position A2 on the photosensitive drum 41 can be moved, so that the amplification factor of the rotational speed of the brush 472 can be reduced. Therefore, the amount of the lubricant LO that enters the developing device 44 does not increase instantaneously, and the occurrence of uneven development can be suppressed.

(Other variations)
Moreover, although the said embodiment illustrated and demonstrated the structure provided with the spring SP which presses the lubricant LO to the brush 472, it is not limited to this. For example, a piezo element may be used instead of the spring SP, or a cylinder or a solenoid may be used. That is, any configuration may be used as long as the force for pressing the lubricant LO against the brush 472 can be made constant.

  Moreover, in the said embodiment, although the photoreceptor drum 41 was illustrated and demonstrated as a rotary body, it is not limited to this. For example, it can be applied to the secondary transfer roller 46 and the fixing device F instead of the photosensitive drum 41.

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

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 20 Automatic document conveyance part 30 Scanner part 40 Image forming part 41 Photosensitive drum (rotating body)
42 Charging device 43 Exposure device (exposure unit)
44 Developing device (developing part)
45 Primary transfer roller (transfer section)
46 Secondary transfer roller 47 Cleaning device 471 Blade 472 Brush (brush member)
473 Lubricant coating device LO Lubricant SP Spring (elastic member)
48 Cleaning Device 50 Paper Feed Unit 61 Mirror 62 Actuator (Mirror Control Unit)
1 Control unit T Intermediate transfer member (transferred member)

Claims (11)

A rotating body having an image carrying function;
An exposure unit that exposes the rotating body to form an electrostatic latent image on the rotating body;
A developing unit for developing the electrostatic latent image formed on the rotating body with a developer;
A transfer unit that transfers the image developed on the rotating body to a transfer target;
A brush member installed so as to contact the rotating body and applying a lubricant to the surface of the rotating body;
A control unit that performs control to change the rotation period of the brush member under a predetermined condition,
The controller is
When the rotation period of the brush member is T1, the rotation period of the rotating body is T2, the center angle between the exposure position by the exposure unit and the transfer position by the transfer unit in the rotating body is α, and the natural number is N,
Formula (1): T2 × α / 360 ° × 1 / N × 9/10 ≦ T1 ≦ T2 × α / 360 ° × 1 / N × 11/10
Controlling the rotation period of the brush member under the condition satisfying the formula (1) ,
An image forming apparatus wherein the exposure position or the transfer position in the rotating body and said movable der Rukoto.   The image forming apparatus according to claim 1, wherein N ≦ 3. The image forming apparatus according to claim 1 or 2, characterized in that it comprises a mirror for moving the exposure position. The image forming apparatus according to claim 3 , further comprising a mirror control unit that moves the mirror back and forth. The image forming apparatus according to claim 3 , further comprising a mirror control unit that controls the tilt of the mirror. A plurality of the exposure units are provided,
Wherein each exposure position by a plurality of exposed portions, an image forming apparatus according to claim 1 or 2, being different from each. The transfer unit, an image forming apparatus according to claim 1 or 2, characterized in that it is movable. The controller changes the rotation cycle of the brush member based on a predetermined number of prints, the number of rotations or the rotational movement distance of the brush member, or the number of rotations or the rotational movement distance of the rotating body. the image forming apparatus according to any one of claims 1 to 7, characterized. The image forming apparatus according to any one of claims 1-8, characterized in that it comprises an elastic member which presses the lubricant into the brush member. The rotating body, an image forming apparatus according to any one of claims 1 to 9, characterized in that a photosensitive drum. Wherein the control unit, the image forming apparatus according to any one of claims 1 to 1 0, characterized in that to control the motor for rotating the brush member.

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