JP3310077B2 - Color image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming method and can be applied to image formation by a color image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art First transfer means for sequentially transferring a plurality of color toner images visualized sequentially on a photosensitive member onto an intermediate transfer member, and a toner image superimposed on the intermediate transfer member are collectively provided. Transfer means for transferring toner onto recording paper, a cleaning blade for removing toner remaining on the intermediate transfer body, an entrance seal for preventing toner from scattering outside the unit, the cleaning blade and the entrance seal There has been known a color image forming method having a contacting / separating means for contacting / separating the intermediate transfer member with the intermediate transfer member.

In such a color image forming method, the timing at which the cleaning blade and the entrance seal abut on the intermediate transfer body may be during transfer from the photosensitive body to the intermediate transfer body, or transfer from the intermediate transfer body to recording paper. Medium and at the end of transfer.

That is, there is the following method for the timing of contact of the cleaning blade with the second transfer means.

A cleaning blade or the like is brought into contact with the intermediate transfer member at the same time as the transfer to the recording paper by the second transfer means is started, or is brought into contact during the transfer.

After the paper transfer is completed, the contact is made.

[0007]

The effect of the cleaning blade on the belt when the cleaning blade comes into contact with the belt as an intermediate transfer member in the above-described technology will be described.

In FIG. 5, reference numeral FB indicates a force generated when the intermediate transfer belt rotates in the direction shown by the arrow.
Here, when the cleaning blade 22-2 comes into contact with the intermediate transfer belt 19, a normal force N is generated from above the intermediate transfer belt with respect to the blade pressing force F.

Here, if the friction coefficient between the intermediate transfer belt and the cleaning blade is μ, a force FC = μN is generated in a direction opposite to the force FB, and a load is applied to the driving portion of the intermediate transfer belt.

At this time, it is assumed that the driving unit has a stronger force than these forces, but the moment when the cleaning blade contacts the intermediate transfer belt or the moment when the cleaning blade separates from the intermediate transfer belt, the force FC
As a result, the speed of the intermediate transfer belt fluctuates as shown in FIGS. The same applies to the approach and separation of the inlet seal.

Therefore, in the technique (1), there is a problem that a load fluctuation occurs on the intermediate transfer member, and an image blur occurs due to a speed fluctuation caused by the load fluctuation.

In the above-described technique, the image is transferred after the paper transfer is completed, and the intermediate transfer belt is further rotated one rotation only for cleaning. There is no image blur, but it takes time to form an image, so-called copy time. There's a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a color image forming method capable of avoiding image shake at the time of transfer due to the contacting / separating operation of the cleaning blade and the entrance seal and shortening the operation time of the apparatus. is there.

[0014]

In order to achieve the above-mentioned object, the present invention provides a cleaning method between the end of the first transfer step by the first transfer means and the start of the second transfer step by the second transfer means. The contact operation of the blade and the entrance seal with the intermediate transfer body is completed, and the contact state of the cleaning blade and the entrance seal with the intermediate transfer body is maintained during the second transfer step. The operation timing of the contacting / separating means is controlled so that the operation of separating the cleaning blade and the entrance seal from the intermediate transfer member is completed before the start of the first transfer step (claim 1).

[0015]

The cleaning blade and the entrance seal do not perform the contact / separation operation during the transfer.

[0016]

【Example】

1. Overview of Color Image Forming Apparatus In FIG. 4, a color copying machine is composed of a color image reading apparatus 1 described later and a color printer 2 forming a printer section, and among these, a color image reading apparatus (hereinafter, referred to as a color scanner). 1) An image of an original 3 is formed on a color sensor 7 via an illumination lamp 4, mirrors 5-1, 5-2, 5-3 and a lens 6, and color image information of the original is For example, blue (Blue), green (Green), red (Re
It is read for each color separation light of d) and converted into an electric image signal. Note that these decomposed lights are expressed as B, G, and R in the following description for convenience.

Based on the B, G, and R color separation image signal intensity levels obtained by the color scanner 1, a color conversion process is performed by an image processing unit (not shown), and black (hereinafter referred to as BK) , Cyan (same, C), magenta (same, M), and yellow (same, Y) color image data.

The color image recording apparatus (hereinafter, referred to as a color printer) 2 described below converts the BK,
Visualization is performed using C, M, and Y toners, and these toner images are superimposed to form a four-color full-color image.

Next, an outline of the color printer 2 will be described.

In FIG. 4, the writing optical unit 8
Is a unit for converting the color image data from the color scanner 1 into an optical signal and performing optical writing corresponding to the original image. The polygon which is rotated by the drive motor 8-3 with the laser beam from the laser light source 8-1 Scanning is performed via a mirror 8-2, and scanning light is guided to a drum-shaped photosensitive member 9 by an fθ lens 8-4 and a reflecting mirror 8-5 to form an electrostatic latent image.

The photoreceptor 9 rotates counterclockwise as indicated by the arrow. Around the photoreceptor, a photoreceptor cleaning unit (including a pre-cleaning static eliminator) 10, a static elimination lamp 11, a charger 12, a potential sensor 13, a BK Devices for performing an electrophotographic copying process, such as a developing device 14, a C developing device 15, an M developing device 16, a Y developing device 17, a development density pattern detector 18, an intermediate transfer belt 19, and the like are arranged.

Each of the developing devices includes a developing sleeve SL that rotates so that the developer faces the photosensitive member 9 in order to develop an electrostatic latent image, a developing paddle PD that rotates to pump and agitate the developer, and a developing device. Toner concentration sensor S
N or the like.

The case where the order of the developing operation (color image forming order) is BK, C, M, and Y will be described below. However, the image forming order is not limited to this.

When the copying operation is started, reading of BK image data is started at a predetermined timing by the color scanner 1, and light writing / latent image formation by laser light is started based on the image data (hereinafter referred to as BK image data). (The same applies to C, M, and Y.)

Before the latent image leading end reaches the developing position of the BK developing device 14, the developing sleeve SL is started to rotate the developer so that development can be performed from the leading end of the BK latent image. To develop the BK latent image with BK toner. Thereafter, the developing operation of the BK latent image area is continued, but when the rear end of the BK latent image passes the BK developing position, the BK developing sleeve S
L is cut off to make the development inoperative.

This is completed at least before the leading end of the C latent image based on the next C image data arrives.

The BK toner image formed on the photoreceptor 9 is transferred onto the surface of the intermediate transfer belt 19 which is driven at the same speed as the photoreceptor (hereinafter, transfer of the toner image from the photoreceptor to the intermediate transfer belt is performed). Belt transfer).

The belt transfer is performed by applying a predetermined bias voltage to a transfer bias roller 20, which is a first transfer means, in a state where the photosensitive member 9 and the intermediate transfer belt 19 are in contact with each other. The BK, C, M, and Y toner images sequentially formed on the photoreceptor 9 are sequentially aligned on the same surface of the intermediate transfer belt 19 to form a four-color superimposed belt transfer image. Perform batch transfer to transfer paper. The configuration and operation of the intermediate transfer belt unit will be described later.

On the photoconductor 9 side, the process proceeds to the step C after the BK step. At a predetermined timing, the reading of the C image data by the color scanner 1 starts, and the C latent image is formed by writing the laser light with the image data. I do.

The C developing device 15 moves the developing position with respect to the developing position.
After the rear end of the previous BK latent image has passed and before the leading end of the C latent image has arrived, the rotation of the developing sleeve SL is started to spike the agent, and the C latent image is developed with the C toner. .

Thereafter, the development of the C latent image area is continued, but when the trailing end of the latent image has passed, the agent is cut off on the C developing sleeve SL as in the case of the BK developing device. This is also completed before the leading end of the next M latent image arrives.

In the steps M and Y, the operations of reading image data, forming a latent image, and developing are the same as those in the steps BK and C described above, and a description thereof will be omitted.

Next, the intermediate transfer belt unit will be described. The intermediate transfer belt 19 is stretched around a drive roller 21, a transfer bias roller 20, and a driven roller group, and is driven and controlled by a drive motor (not shown) as described later.

The belt cleaning unit 22 is configured as shown in FIG.
3, a cleaning blade 22-2, an inlet seal 22-4, and a means 22-3 for contacting / separating these blades from the belt. 3 allows the belt to be separated from the belt surface.

The paper transfer unit 23 includes a paper transfer bias roller 23-1 and a means 23-3 for contacting and separating from the belt.
It is composed of

The paper transfer bias roller 23-1 is normally separated from the surface of the belt 19, but the timing is set when the four-color superimposed images formed on the surface of the intermediate transfer belt 19 are collectively transferred to the transfer paper. 23-3
And a toner image is transferred to paper while applying a predetermined bias voltage by the roller 23-1.

The transfer paper 24 is formed by a paper feed roller 25,
The sheet is fed by the registration roller 26 at the timing when the leading end of the four-color superimposed image on the intermediate transfer belt surface reaches the paper transfer position.

The manner of movement of the intermediate transfer belt 19 is as follows.
The following three methods can be considered as an operation method after the belt transfer of the BK toner image of the color has been completed to the rear end portion, and one of these methods is effective, or one of these methods is efficient according to the copy size (in terms of copy speed or the like). It is operated by a combination of various methods.

(1) -Constant speed forward system This is a system in which the transfer belt continues to move at a constant speed even after the toner image of the first color is transferred. The image processing is performed at a timing such that the leading edge of the image of the next color toner image to be subjected to the visible image processing on the photosensitive member 9 coincides with the leading edge of the image on the intermediate transfer belt 19. The process for that is as follows.

[0040] After the belt transfer of the BK toner image, the forward movement is continued at a constant speed.

[0041] When the front end position of the BK image on the surface of the belt 19 reaches the belt transfer position of the contact portion with the photoconductor 9 again, the front end portion of the next C toner image on the photoconductor 9 side is exactly at that position. The image is formed at a proper timing.

As a result, the C image is transferred onto the intermediate transfer belt 19 in a state of being accurately aligned with the BK image.

. Thereafter, the process proceeds to the M and Y image processes by the same operation, and a belt transfer image of four-color superposition is obtained.

[0044] The four-color superimposed toner image on the belt surface is collectively transferred to the transfer paper 24 as described above while moving forward as it is after the fourth color Y toner image belt transfer step.

(2) Skip forward system This is more effective than the case where the transfer belt is separated from the photoconductor after the first color toner image is transferred, and the first color toner image is transferred. This is a method in which the photosensitive drum is moved at a high speed in the same direction as before, and when the photosensitive drum is moved by a predetermined amount, the moving speed is switched to the initial moving speed and the photosensitive member is brought into contact again.

This method is executed, for example, when the length of an image to be transferred is shorter than the length of the transfer belt, and can prevent a cycle time for forming an image on the photosensitive member from becoming longer. The process for this is as follows.

[0047] When the belt transfer of the BK toner image is completed, the belt 19 is separated from the surface of the photoreceptor 9 and skipped at a high speed in the forward movement direction, and after moving a predetermined amount, the speed is returned to the original forward movement speed. Thereafter, the belt 19 is brought into contact with the photoconductor 9 again.

[0048] Then, when the leading end position of the BK image on the belt 19 surface reaches the belt transfer position again, an image is formed on the photoreceptor 9 side at a timing such that the leading end portion of the next C toner image is exactly at that position. I have.

As a result, the C image is belt-transferred so as to be accurately aligned with the BK image.

[0050] Thereafter, the process proceeds to the M and Y image processes by the same operation to obtain a four-color superimposed belt transfer image.

[0051] The four-color superimposed toner image on the surface of the belt 19 is collectively transferred onto the transfer paper 24 at the same forward movement speed following the transfer process of the Y toner image belt for the fourth color.

(3) Reciprocating (quick return) method In this method, after the toner image of the first color is transferred, the transfer belt is separated from the photosensitive member, and the transfer belt is moved in the reverse direction at a higher speed than before. To wait for the position of the previously transferred toner image to match the position of the toner image of the next color carried on the photoconductor, and then again contact the transfer belt with the photoconductor. In this manner, the movement is started in the same direction as the photosensitive member, and this operation is continued until the transfer of the final color toner image.

This method relates to control when the image position on the transfer belt is adjusted to the image position on the photosensitive member.
Instead of moving the transfer belt in the forward direction, it only reverses the amount of movement that has been done so far.Since it is not necessary to secure a large amount of movement of the transfer belt, control is simplified. The process for this is as follows.

[0054] When the belt transfer of the BK toner image is completed, the transfer bias roller 20 shown in FIG. 4 is moved to separate the belt 19 from the surface of the photoconductor 9, and the forward movement is stopped, and at the same time, the belt 19 is returned at a high speed in the reverse direction.

In the return, the front end position of the BK image on the surface of the belt 19 passes through a position corresponding to the belt transfer in the reverse direction, and after moving a predetermined distance, stops and enters a standby state.

[0056] Next, when the leading end of the C toner image on the photoconductor 9 reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 is started again in the forward movement direction. Further, the transfer bias roller 20 shown in FIG. 4 is moved to bring the belt 19 into contact with the surface of the photoconductor 9 again.

Also in this case, the C image is
The belt transfer is performed under the condition that the image is accurately overlapped with the K image.

[0058] Thereafter, the process proceeds to the M and Y image processes by the same operation to obtain a four-color superimposed belt transfer image.

[0059] Subsequent to the belt transfer process of the Y toner image of the fourth color, the toner is moved forward at the same speed without returning, and the four-color superimposed toner image on the surface of the belt 19 is collectively transferred to the transfer paper 24.

The transfer paper 24 on which the four-color superimposed toner image has been collectively transferred from the intermediate transfer belt surface is transferred to the paper transport unit 2.
At 7, the toner image is melted and fixed by the fixing roller 28-1 and the pressure roller 28-2 controlled to a predetermined temperature, and is carried out to the copy tray 29 to obtain a full-color copy.

The surface of the photoconductor 9 after the belt transfer is cleaned by a photoconductor cleaning unit 10.
Further, the charge is uniformly removed by the charge removing lamp 11.

At the time of repeat copying, the color scanner 1
The operation of (1) and the image formation on the photoconductor 9 are performed on the first sheet Y (4
The process proceeds to a BK (first color) image process for a second sheet at a predetermined timing following the color process) image process.

Further, the intermediate transfer belt 19 continues the step of batch-transferring the first four-color superimposed image onto transfer paper.
The second BK toner image is belt-transferred to the area whose surface has been cleaned by the cleaning unit 22. Thereafter, the operation is the same as that of the first sheet.

The transfer paper cassettes 30, 31, 32,
Transfer papers of various sizes are stored in 33, and are fed and conveyed toward the registration rollers 26 at appropriate timing from a storage cassette of the size paper designated by an operation panel (not shown). Reference numeral 34 denotes a manual paper feed tray for OHP paper or thick paper.

The above description has been given of the copy mode for obtaining four full colors. However, in the case of the three-color copy mode and the two-color copy mode, the same operation is performed for the designated color and the number of times. .

In the case of the single-color copy mode, only the developing device of the color is set to the developing operation (spring) and the intermediate transfer belt 19 is operated until a predetermined number of sheets are completed.
Is driven at a constant speed in the forward direction while being in contact with the surface of the photoreceptor 9, and the copying operation is performed with the belt cleaner 22 still in contact with the belt 19.

2. Configuration of the contacting / separating means (see FIGS. 1 to 3)
Is configured as part of The cleaning belt unit is configured in a box-shaped frame. This frame and the rib-shaped part formed inside the frame are
It is called a structure, and is denoted by reference numeral 35. This structure 35 is a stationary member.

A solenoid 36 is fixed to the structure 35. One end of a lever 37 is pivotally connected to the plunger 36P of the solenoid 36, as shown in FIG. The other end of the lever 37 is overlapped with the bent portion of the L-shaped lever 38 and is pivotally attached.

One end of the lever 38 is pivotally attached to a shaft 39. The shaft 39 is implanted in the structure 35. A roller 40 is pivotally attached to the other end of the lever 38.

Therefore, if the solenoid 36 is turned on,
The plunger 36P is sucked, the lever 38 swings, and the roller 40 moves in the direction of arrow A in FIG. When the solenoid is turned off, the roller 40 swings in the direction of arrow B.

In the swing range of the roller 40 when the solenoid 36 is turned on and off, a bent piece-like pushed portion 41 is located. The pushed portion 41 has a length in the axial direction of the drive roller 21, and is configured as a part of a blade bracket 42 having both ends bent in a U-shape. The bent portions at both ends of the blade bracket are pivotally attached to a shaft 43. The shaft 43 is implanted in the structure 35.

As shown in FIG. 1, the blade bracket 4
L-shaped plate members 44 and 45 are attached to the second inclined surface. Further, a cleaning blade 22-2 is attached to the tip of the overlapping portion of the plate members 44 and 45.

With the swing of the blade bracket 42, the cleaning blade 22-2 moves the intermediate transfer belt 1
9 is performed. A receiving roller 46 is provided on the back side of the intermediate transfer belt 19 corresponding to a portion where the cleaning blade contacts.

The tip of the pushed portion 41, the roller 40
One end of an elastic spring 47 is hung on a portion other than the contact portion with the spring. The other end of the spring is hung on the structure 35. Therefore, the blade bracket 42 is urged counterclockwise about the shaft 43.

Therefore, when the solenoid 36 is on,
As shown by the arrow in FIG. 3, the plunger is sucked, and the roller 40 pushes the pushed portion 41 against the elasticity of the spring 47.
9 (see FIG. 2).

When the solenoid 36 is turned off, FIG.
The roller 40 moves in the direction of arrow B because the plunger is opened as shown by the arrow in FIG. That is, since the roller 40 that has prevented the movement of the pushed portion 41 by the spring 47 escapes, the cleaning blade 22-2 is in contact with the intermediate transfer belt 19 due to the elasticity of the spring 47 as shown in FIG. become.

The mechanism for contacting / separating the cleaning blade has been described above. In this embodiment, the entrance seal 22-4 is also contacted / separated from the intermediate transfer belt 19 in conjunction with the operation for contacting / separating the cleaning blade. I have.

The entrance seal 22-4 is for closing the toner scraped off by the cleaning blade 22-2 so as not to scatter outside the cleaning belt unit 22.

Therefore, when the cleaning blade contacts the intermediate transfer belt, the entrance seal also contacts the intermediate transfer belt, and when the cleaning blade separates, the entrance seal separates.

In order to perform such an operation, the entrance seal 22
-4 is attached to an inlet seal bracket 49 pivotally attached to a shaft 48 implanted in the structure 35.

A stepped inlet seal pin 50 is implanted in the inlet seal bracket 49. A torsion coil spring 51 is provided between the inlet seal pin 50 and the structure 35 in a state wound around the inlet seal pin 50.

The elasticity of the torsion coil spring 51 urges the inlet seal bracket 49 clockwise. The rotation of the inlet seal bracket due to the urging force of the spring causes the cleaning blade 22- to rotate as shown in FIG.
2 is in contact with the intermediate transfer belt when the entrance seal 22
-4 is prevented by contact with the intermediate transfer belt.

Also, as shown in FIG. 2, when the cleaning blade 22-2 is separated from the intermediate transfer belt, the entrance seal pin 50 is prevented from contacting the lever 52.

The base end of the lever 52 is fixed to the blade bracket 42. The positional relationship between the lever 52 and the inlet seal pin 50 is determined so that the above-described contact / separation operation can be performed.

With the above structure, the solenoid 36 is turned on,
The cleaning blade 22-2 and the entrance seal 22-4 are controlled to contact and separate from the intermediate transfer belt 19 in conjunction with turning off.

The solenoid 36, the levers 37 and 38, the blade bracket 42, the spring 47, the inlet seal bracket 49, the torsion coil spring 51 and the like constitute the main members of the contact / separation means 22-3.

3. Operation timing of contact / separation means. Referring to FIG. 1 to FIG. 4 and FIG. 7, when the first transfer step on the intermediate transfer belt 19 by the transfer bias roller 20 as the first transfer means is completed (reference numeral a in FIG. 7).
From the time) indicated by _1, the second transfer process starting with a sheet transfer bias roller 23-1 serving as a second transfer means (between the point shown in FIG. 7 with reference numeral a ₂₎ (in FIGS. 7 (a) The contact operation of the cleaning blade and the entrance seal with the intermediate transfer member is completed within the time indicated by.

As described above, during the transfer step, the cleaning blade and the entrance seal are separated from the intermediate transfer belt, and there is no operation of contact and separation, so that image blur does not occur.

[0089] During the second transfer process using the paper transfer bias roller 23-1, the contact state of the cleaning blade 22-2 and the entrance seal 22-4 with the intermediate transfer belt 19 is maintained.

That is, in FIG. 7, the time when the paper transfer bias roller 23-1 is in "contact" is the cleaning blade 2
2-2 and the inlet seal 22-4 are included in the "contact" time.

As described above, during the transfer step, the state of contact of the cleaning blade and the entrance seal with the intermediate transfer belt is maintained, and there is no operation of contact and separation, so that image blur does not occur.

[0092] At the end of the second transfer step (reference b in FIG. 7)
When the first transfer process starts when) the following indicated by ₁ within the time indicated by (between time) indicated by a symbol b ₂ in FIG. 7 (in FIG. 7 (b)) to the cleaning blade and the intermediate transfer inlet seal The separating operation for the belt is terminated.

As described above, since the operation of separating the cleaning blade and the entrance seal from the intermediate transfer belt has been completed before the transfer step, no image blur occurs.

In this embodiment, the cleaning of the intermediate transfer belt is performed during the second transfer step, and there is no need to rotate the intermediate transfer belt only for cleaning as in the conventional technique. However, cleaning does not increase the cycle time for image formation.

[0095]

According to the present invention, it is possible to avoid image blurring at the time of transfer due to the contact / separation operation of the cleaning blade and the entrance seal, and to shorten the operation time of the apparatus.

[Brief description of the drawings]

FIG. 1 is a partial sectional front view of a cleaning belt unit illustrating a contact / separation unit according to the present invention.

FIG. 2 is a partial cross-sectional front view of a cleaning belt unit illustrating a contact / separation unit according to the present invention.

FIG. 3 is a view for explaining a solenoid as a part of the contact / separation means according to the present invention and its peripheral members.

FIG. 4 is a diagram illustrating an overall outline of a color image forming apparatus according to the present invention.

FIG. 5 is a diagram for explaining the influence of the contact and separation of the cleaning blade with respect to the intermediate transfer belt.

FIG. 6 is a diagram for explaining the influence of the contact and separation of the cleaning blade with respect to the intermediate transfer belt.

FIG. 7 is a timing chart illustrating the operation of the contact / separation unit.

[Explanation of symbols]

19 Intermediate Transfer Belt (as Intermediate Transfer Body) 20 (First Transfer Means) Transfer Bias Roller 22-2 Cleaning Blade 22-3 Contacting / Separating Means 22-4 Entrance Seal 23-1 (Second Transfer Means) Paper transfer bias roller

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/16 G03G 15/01

Claims (1)

(57) [Claims] A first transfer means for sequentially transferring a plurality of color toner images sequentially visualized on a photoreceptor onto an intermediate transfer member; and a toner image superimposed on the intermediate transfer member. Transfer means for transferring toner onto recording paper, a cleaning blade for removing toner remaining on the intermediate transfer body, an inlet seal for preventing toner from scattering outside the unit, the cleaning blade and the inlet seal In a color image forming method using a contacting / separating means for contacting / separating the intermediate transfer member from the intermediate transfer body, wherein a second transfer step by the second transfer means is started from the end of the first transfer step by the first transfer means The contact operation of the cleaning blade and the entrance seal with the intermediate transfer member is completed during the second transfer process, and the cleaning blade and the entrance seal The contact state with the intermediate transfer member is maintained, and the separating operation of the cleaning blade and the entrance seal from the intermediate transfer member is completed between the end of the second transfer step and the start of the next first transfer step. Controlling the operation timing of the contact / separation unit so as to cause the contact.