JPH10319817A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stable image forming device capable of preventing the formation of an abnormal image by preventing the imperfection of the engagement of joint means due to the attachment/detachment of an image carrier. SOLUTION: This image forming device is constituted of an image forming part having the image carrier 1, developing units 2B, 3Y, 3M and 3C and an intermediate transfer body 4, an attaching/detaching means for making the image carrier 1 attachable/detachable to/from a device main body, and the joint means for transmitting driving force to the image carrier 1. A toner image 36 is formed on the image carrier 1 during an initial stage operation before a printing operation. Consequently, the image carrier 1 and the intermediate transfer body 4 slip in the contact part by the lubricating work of the toner grains of the toner image 36 which is formed on the image carrier 1 during the initial stage operation before the printing operation, so that the joint means become an engaging state to transmit the driving force to the image carrier 1 and rotationally drive it surely. Thus, the abnormal rotation of the image carrier 1 in the printing operation after that is prevented to effectively prevent the generation of the abnormal image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine or a printer for recording and forming an image on a sheet material by an electrophotographic method or the like.

[0002]

2. Description of the Related Art A color laser beam printer, which is one form of a conventional image forming apparatus, includes an image carrier rotating at a constant speed, a fixed black developing device, and three rotatable color developing devices (yellow, magenta, and magenta). And an intermediate transfer member for holding a color image developed and multi-transferred in the image forming unit and further transferring the color image to a sheet material fed from a feeding unit. Have. That is, an image is sequentially formed for each color on the image carrier by the developing device, and the image is sequentially transferred onto the intermediate transfer member in a superimposed manner. The image that has been multiplex-transferred onto the intermediate transfer member is simultaneously transferred to a sheet material fed from a feeding unit and fed to a transfer position. Then, the sheet material on which the image has been transferred is conveyed to a fixing unit, where the transferred image is fixed, and then discharged by a discharge roller onto a discharge tray on the upper surface of the apparatus.

Incidentally, the three rotatable color developing units, the fixed black developing unit, and the image carrier are configured to be individually detachable from the printer main body. Further, the image carrier is disposed between the black developing device and the intermediate transfer member, and the black developing device and the intermediate transfer member are configured to be able to contact and separate from the image carrier. That is, in the black developing device, the developing sleeve is in contact with the image carrier at a minute interval during normal use,
Also, the intermediate transfer member is in contact with the image carrier at a constant pressure.

A driving force for rotating the image carrier at a constant speed is transmitted by a joint means that can be brought into contact with and separated from the image carrier, while a driving force for rotating the intermediate transfer member at a constant speed is transmitted by a gear. The peripheral velocities of the body and the intermediate transfer body are set to be the same.

When the image carrier is attached or detached, first, the black developing device and the intermediate transfer body are separated from the image carrier, and then the image carrier is moved to the printer body along the printer body and the guide provided on the image carrier. On the other hand, the image carrier is pulled out coaxially with the image carrier, and then the image carrier is inserted along the guide, and the rotating knob provided on the image carrier is rotated to engage the detachable coupling means. After that, the black developing device and the intermediate transfer member are brought into contact with the image carrier to perform the attaching / detaching operation.

[0006]

However, in the above-mentioned conventional color laser beam printer, when the image carrier is mounted, first, the rotary knob provided on the image carrier is rotated to engage the joint means which can be brought into contact with and separated from the image carrier. However, if one forgets to rotate the rotary knob, the coupling means will not be engaged. If the image carrier is stopped, the drive side of the joint means rotates and the joint means is engaged, but the image carrier is rotated following the intermediate transfer member, so that the joint means remains unengaged. When the image forming operation is performed, an abnormal image may be formed without the image carrier rotating normally.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to prevent a failure in engagement of coupling means due to attachment / detachment of an image carrier, and to provide a stable image without forming an abnormal image. To provide an improved image forming apparatus.

[0008]

In order to achieve the above object, the invention according to claim 1 provides an image carrier, a developing device,
An image forming apparatus comprising: an image forming unit having an intermediate transfer member; attaching / detaching means for attaching / detaching the image carrier to / from the main body; and coupling means for transmitting a driving force to the image carrier. Wherein a toner image is formed on the image carrier during an initial operation before a printing operation.

According to a second aspect of the present invention, in the first aspect of the present invention, detecting means for detecting that the carrier is mounted on the main body is provided, and the image carrier is mounted on the apparatus main body. When detecting, a toner image is formed on the image carrier.

According to a third aspect of the present invention, in the first aspect of the present invention, the toner image formed on the image carrier is transferred onto the intermediate transfer member, and this is repeated a plurality of times. In which multiple toner images are formed.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the circumferential length of the toner image formed on the intermediate transfer member is set to be at least 以上 of the outer circumferential length of the image carrier. Features.

According to the first aspect of the present invention, a toner image is formed on an image carrier during an initial operation before a printing operation. Therefore, the image carrier and the intermediate transfer member are lubricated by toner particles. Slips at the abutting portion, the coupling means is engaged, and the driving force is transmitted to the image carrier to rotate the image carrier reliably, thereby preventing abnormal rotation of the image carrier in a subsequent printing operation. As a result, occurrence of an abnormal image is effectively prevented.

According to the second aspect of the present invention, the toner image is formed on the image carrier only when the image carrier is replaced, not every time during the initial operation. And the toner consumption is reduced.

According to the third aspect of the present invention, since multiple toner images are formed on the intermediate transfer member, the amount of toner increases upon arrival at the contact portion between the image carrier and the intermediate transfer member, and the toner particles are increased. High lubrication effect is obtained, the coupling means is securely engaged, the image carrier is more reliably driven to rotate, and the occurrence of abnormal images due to abnormal rotation of the image carrier in the subsequent printing operation is more reliable. Is prevented.

According to the fourth aspect of the present invention, since the circumferential length of the toner image formed on the intermediate transfer member is set to be at least の of the outer peripheral length of the image carrier, the image carrier and the intermediate transfer member are separated. During the slip, the toner particles are always present in the contact portion, and the coupling means is reliably engaged, so that the image carrier is more reliably driven to rotate.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following embodiments, a laser beam printer will be described as an example of an image forming apparatus.

<First Embodiment> FIGS. 1 and 2 are partially enlarged views of a joint portion of an image forming apparatus according to a first embodiment of the present invention, and FIG. 3 is a side sectional view showing a schematic configuration of the image forming apparatus. ,
FIG. 4 is a partially enlarged sectional view of a main part of the image forming apparatus.

First, an overall configuration of a color laser beam printer, which is an embodiment of the image forming apparatus, will be outlined with reference to FIG.

The color laser beam printer according to the present embodiment comprises an image carrier 1 rotating at a constant speed, a fixed black developing device 2B and three rotatable color developing devices 3B.
An image forming unit including Y, 3M, and 3C, and an intermediate transfer that holds the color image developed and multiplex-transferred in the image forming unit and further transfers the color image to a sheet material S fed from a feeding unit. It has a body 4.

The developing units 2B, 3Y, 3M, 3
Images are sequentially formed on the image carrier 1 for each color by C, and the images formed on the image carrier 1 are sequentially multiplex-transferred to the intermediate transfer member 4. The image multiplex-transferred onto the intermediate transfer member 4 is
The image is transferred onto the sheet material S fed from the feeding unit 16. Then, the sheet material S is conveyed to the fixing unit 5 and after the transfer image is fixed, is discharged to the discharge tray 9 on the upper surface of the apparatus by the discharge roller pairs 6, 7, and 8, and is stacked.
Incidentally, the three color developing devices 3Y, 3 which are rotatable and movable.
M, 3C and the fixed black developing device 2B are configured to be individually detachable from the printer main body.

Next, the configuration of each section of the image forming apparatus will be sequentially described in detail.

The charging means is a charging roller 11 to which a voltage is applied.
The charging roller 11 is pressed against the image carrier 1, and the charging roller 11 contacts the image carrier 1 before forming the latent image.
Is uniformly charged.

Exposure to the image carrier 1 is performed by a scanner unit 12 having a laser diode (not shown).
The laser diode emits light in response to the image signal, and irradiates a laser beam to the polygon mirror 12a. The polygon mirror 12a is rotated at a high speed by a scanner motor to reflect laser light, and the laser light reflected by the polygon mirror 12a is coupled to the coupling lens 12b and the reflection mirror 12a.
Through c, selective exposure is performed on the outer peripheral surface of the image carrier 1 in accordance with the image signal. Then, an electrostatic latent image for each color is formed on the outer peripheral surface of the image carrier 1 by this exposure.

The black developing device 2B is a fixed developing device, and is positioned so that its developing sleeve 2BS is opposed to the surface of the image carrier 1 via a minute gap. Then, at the time of development, the latent image on the image carrier 1 is developed by receiving a bias application and a rotation drive to the developing sleeve 2BS to form a toner image.

Three color developing units that can be rotated and moved, that is, developing units 3 with yellow, magenta, and cyan toners
Y, 3M, and 3C are rotatably disposed in the developing rotary 13 that is rotatable about a shaft 13a. When forming an image, the developing sleeve 3YS is stopped at a position facing the image carrier 1, and the developing sleeve 3YS is moved there.
It is positioned so as to face the surface via a minute gap. Therefore, each developing device (in the illustrated example, the yellow developing device 3
When Y) is rotated to the developing position, it is connected to the high-voltage power supply of the printer main body, a developing bias is applied to the developing sleeve 3YS, and at the same time, the developing sleeve 3YS is coupled with a driving means from a driving source to perform predetermined rotation. By doing so, the latent image on the image carrier 1 is developed to form a toner image on the surface of the image carrier 1.

The intermediate transfer member 4 applies the toner image visualized by the developing units 3Y, 3M, 3C and 3B on the image carrier 1 four times during the color image forming operation (four colors of yellow, magenta, cyan and black). ), The image carrier 1 rotates clockwise (in the direction of the arrow in FIG. 3) in synchronization with the outer peripheral speed of the image carrier 1.

The cleaner blade 14 cleans the toner remaining on the image carrier 1 after the toner image visualized on the image carrier 1 has been transferred to the intermediate transfer member 4. Toner is waste toner container 1
5

The feeding section 16 is for feeding the sheet material S to the transfer position T2, and has a cassette 17 for storing the sheet material S loaded at the bottom of the apparatus main body. At the time of image formation, the feed rollers 18 and 1 correspond to the image forming operation.
9 and 20 are rotated, and the sheet material S is removed from the cassette 17 by one.
The sheet material S is separated and fed one by one, and the sheet material S is guided by the guide plate 21 and reaches the registration roller 23 via the transport roller 22. During the image forming operation, the registration roller 23 performs a non-rotating operation of stopping the sheet material S in a standby state and a rotating operation of transporting the sheet material S toward the intermediate transfer body 4 in a predetermined sequence, and a transfer process as a next process is performed. The position of the image at the time and the sheet material S are aligned.

Then, the intermediate transfer member 4 having received the multiple transfer of the toner image visualized on the image carrier 1 sandwiches the sheet material S at the transfer position T2 with the transfer roller 24 to which the voltage is applied, and conveys it. Thereby, the toner images of the respective colors on the intermediate transfer body 4 are simultaneously transferred onto the sheet material S in a multiplex manner.

The fixing unit 5 includes a pressure roller 5 that is driven to rotate.
b, and a fixing roller 5a which is pressed against and applies heat and pressure to the sheet material S. Therefore, in the fixing unit 5, the toner images of the respective colors are transferred by holding the respective color toner images secondary-transferred from the intermediate transfer body 4 as described above and passing the sheet material S conveyed. S is fixed as a permanent image on S.

In the image forming operation, first, the feed rollers 18, 19, and 20 are driven to rotate to separate and feed out the sheet material S in the feed cassette 17 one by one, and this is transported to the registration roller 23. I do. At this time, the registration rollers 23 are stopped, the skew of the sheet material S is corrected, and the sheet material S temporarily stops at this position and waits.

The image carrier 1 whose surface has been uniformly charged by the charging roller 11 is subjected to laser exposure at the exposure position E when an arbitrary point on the outer periphery of the intermediate transfer member 4 comes to the position N1. An image is formed. The distance a from the exposure position E of the image carrier 1 to the transfer position T1 which is a contact portion with the intermediate transfer member 4 in the counterclockwise direction, and the distance b from the position N1 of the intermediate transfer member 4 to the transfer position T1 are Equally (a = b), and therefore, after a lapse of a predetermined time, the exposure position E at the start of writing an image
And the position N1 on the intermediate transfer member 4 coincides with the transfer position T1. That is, the image is positioned at any position N1 with respect to the intermediate transfer member 4.
Formed counterclockwise at the tip.

Next, an image forming operation for each color will be described.

First, the scanner section 12 irradiates a yellow image with a laser to form a yellow latent image on the image carrier 1. At the same time as the formation of this latent image, the yellow developing unit 3Y
Is driven, and a voltage of the same polarity and substantially the same potential as the charging polarity of the image carrier 1 is applied to the yellow developing device 3Y so that yellow development is performed so that the yellow toner adheres to the latent image on the image carrier 1. At the same time, the yellow toner image on the image carrier 1 is primarily transferred to the outer periphery of the intermediate transfer member 4 at a first transfer position T1 slightly downstream of the developing position. At this time, primary transfer is performed by applying a voltage having a polarity opposite to that of the yellow toner to the intermediate transfer member 4, and an image (toner image) is transferred from an arbitrary position N1 to a position N2 of the intermediate transfer member 4. When the transfer of the yellow toner image to the intermediate transfer member 4 is completed (that is, the position N2 is set to the first transfer position T
1), the developing rotary 13 rotates clockwise, the next magenta developing unit 3M rotates and moves,
It is positioned at a position facing.

Next, an arbitrary position N1 of the intermediate transfer member 4
When the (tip of the yellow image) reaches the original position N1 after making one round, similarly to the case of yellow, laser irradiation of the magenta image is started by the scanner unit 12, and the latent image on the image carrier 1 is formed. The magenta toner image is developed. Then, the magenta toner image on the image carrier 1 is transferred to the first transfer position T.
At 1, the yellow toner image is transferred onto the intermediate transfer member 4 in a superimposed manner. When the transfer of the magenta toner to the intermediate transfer member 4 is completed (that is, when the position N2 has passed the first transfer position T1), the developing rotary 13 rotates clockwise, and the next cyan developing device 3C rotates and moves. It is positioned at a position facing the image carrier 1.

Next, an arbitrary position N1 of the intermediate transfer member 4
When the (front end of the yellow / magenta image) further goes around to the original position N1, the laser irradiation of the cyan image is started by the scanner unit 12 as in the case of magenta, and the image on the image carrier 1 is started. A cyan toner image is developed on the latent image. Then, the cyan toner image on the image carrier 1 is transferred onto the intermediate transfer member 4 at the first transfer position T1 so as to overlap the yellow and magenta toner images. When the transfer of the cyan toner to the intermediate transfer member 4 is completed (that is, when the position N2 has passed the first transfer position T1), the developing rotary 13 rotates clockwise by a predetermined angle (60 ° in the present embodiment). The developing units 3Y, 3M and 3C are not present at the position facing the image carrier 1. That is, 2 in the developing rotary 13
The space between the two developing units (for example, between the cyan developing unit 3C and the yellow developing unit 3Y) is opposed to the image carrier 1.

Next, an arbitrary position N1 of the intermediate transfer member 4
When (the leading end of the yellow / magenta / cyan image) makes another round to reach the original position N1, the laser irradiation of the black image is started by the scanner unit 12 as in the case of cyan, and the black developing device 2B Develops a black toner image. Then, the black toner image on the image carrier 1 is further superimposedly transferred onto the intermediate transfer member 4 at the first transfer position T1.

The latent image formation, development and toner transfer to the intermediate transfer member 4 are sequentially performed four times in the order of yellow, magenta, cyan and black.
Surface of yellow, magenta, cyan and black
Thus, a full-color image composed of the different types of toner is formed.

Before the transfer of the black toner to the intermediate transfer member 4 is completed (that is, before the position N1 which is the image front end of the intermediate transfer member 4 on which the full-color image has been formed reaches the second transfer position T2). ), The sheet material S which has been waiting by the registration roller 23 is started to be conveyed at a proper timing. At the same time, the transfer roller 24, which has not been in contact with the intermediate transfer member 4, is moved upward by a cam (not shown) while waiting in a downward direction during the four times of image formation for each color, so that the sheet material S is The full-color image on the intermediate transfer member 4 is simultaneously transferred to the sheet material S in four colors by applying a bias having a characteristic opposite to that of the toner to the transfer roller 24 at the same time as pressing the transfer member 4 at the second transfer position T2.

The sheet material S having passed through the second transfer position T2 is peeled off from the intermediate transfer member 4, and is conveyed to the fixing section 5 where the toner image is fixed. The image is discharged onto the discharge tray 9 with the image surface facing downward, and a series of image forming operations is completed.

Incidentally, the image carrier 1, the charging roller 1
1, an image carrier unit 1U comprising a cleaner blade 14 and a waste toner container 15 is provided with a rail 1L, and a printer body is provided with a guide 29 for guiding the rail 1L. It is configured so that it can be inserted into and removed from the printer body in the same direction as the image carrier 1 along the line 29.

In order to replace the image carrier unit 1U for the life of the image carrier 1 or the like, first, the black developing device guide 27 is rotated by a rotating means (not shown). By rotating clockwise about the shaft 28,
The black developing device 2B is separated from the image carrier 1. Further, the intermediate transfer member 4 is rotated by a rotating means (not shown).
By swinging counterclockwise around S, the intermediate transfer member 4 is separated from the image carrier 1. Then, the image carrier unit 1U is removed from the printer main body along the guide 29 in the coaxial direction with the image carrier 1. Similarly, the image carrier unit 1U is inserted into the printer body in the reverse order, and the black developing unit 2B and the intermediate transfer body 4 are brought into contact with the image carrier 1, thereby completing the replacement of the image carrier unit 1U.

On the other hand, as shown in FIG. 1, the joint portion 30 includes an image carrier 1J provided on the back side of the image carrier 1 and a drive shaft 3
1, a joint piece 32, a joint pin 33 and a joint spring 34. When the drive shaft 31 rotates at a constant speed by a gear mechanism (not shown), the joint piece convex portion 32a engages with the image carrier shaft concave portion 1Js. Thus, the driving force is transmitted to the image carrier shaft 1J via the joint pin 33 and the joint top 32.

Immediately after the image carrier unit 1U is inserted into the printer main body, the joint piece convex portion 32a and the image carrier shaft concave portion 1Js are out of phase, so that the joint piece 32 is pushed by the image carrier shaft 1J. , The joint spring 34 is compressed and the drive shaft 3
1, the joint piece convex portion 32a is not engaged with the image carrier shaft concave portion 1Js.

When the replacement of the image carrier unit 1U is completed and the door of the printer body (not shown) is closed, an initial operation before printing is performed. During this initial operation, a toner image 36 is formed on the surface of the image carrier 1 as shown in FIG.

Although no driving force is transmitted to the image carrier 1 via the joint 30, the image carrier 1 is driven to rotate by the intermediate transfer member 4 in contact with the image carrier 1, and the image carrier 1 is connected to the image carrier shaft 1 J by a joint. Since the top 32 rotates at a constant speed, the joint top convex portion 32a does not engage with the image carrier shaft concave portion 1Js while being out of phase. Then, the toner image 36 formed on the surface of the image carrier 1 is transferred to the transfer position T1 (that is, the image carrier 1 and the intermediate transfer member 4).
The image carrier 1 and the intermediate transfer member 4 slip at the contact portion due to the lubricating action of the toner particles, and the image carrier 1 is no longer driven by the intermediate transfer member 4 to rotate. The rotation of 1 stops.

When the rotation of the image carrier 1 is stopped as described above, the rotation of the image carrier shaft 1J is also stopped at the joint portion 30, but the joint piece 32 is rotated, and therefore, as shown in FIG. As described above, when the phases of the joint top convex portion 32a and the image carrier shaft concave portion 1Js match, the joint top 32 is pushed back by the joint spring 34, and the joint top convex portion 32a enters the image carrier shaft concave portion 1Js and engages. Is done.

As described above, when the toner image 36 is formed on the surface of the image carrier 1 during the initial operation, the image carrier 1 and the intermediate transfer member 4 slip at the contact portion, and the joint frame convex portion is formed. Since the image carrier 32a and the image carrier shaft recess 1Js are automatically engaged with each other, the image carrier 1 does not rotate abnormally in the subsequent printing operation, and no abnormal image is formed.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a partial plan view of a main part of the image forming apparatus according to the present embodiment, and the configuration of the entire image forming apparatus according to the present embodiment is the same as that of the first embodiment. Detailed description is omitted.

In this embodiment, the image carrier unit 1U
A detection means 35 for detecting that the image carrier unit 1U is mounted on the back side of the camera.

The detecting means 35 is constituted by a micro switch. When the image carrier unit 1U is replaced and reaches the mounting position of the printer main body, the projection 38 of the image carrier unit 1U is moved by the lever of the micro switch 35. 3
By pressing 5a, it is possible to detect that the image carrier unit 1U is mounted on the printer main body.

The detection means 35 detects that the image carrier unit 1U is mounted on the printer body,
Only when it is determined that the image carrier unit 1U has been replaced, a toner image 36 is formed on the surface of the image carrier 1 during the initial operation similar to the first embodiment.

Therefore, according to the present embodiment, the toner image 36 is formed on the surface of the image carrier 1 only when the image carrier unit 1U is replaced, not every time during the initial operation. The frequency of forming
The toner consumption can be reduced.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view of a main part of the image forming apparatus according to the present embodiment, and since the entire configuration of the image forming apparatus according to the present embodiment is the same as that of the first embodiment, Description is omitted.

In the present embodiment, the toner image 36 formed on the surface of the image carrier 1 during the initial operation is transferred onto the surface of the intermediate transfer member 4, and this operation is repeated a plurality of times, thereby repeating the operation.
The multi-toner image 37 is formed on the surface of the image carrier 1. When the toner reaches the contact portion between the image carrier 1 and the intermediate transfer member 4, the amount of toner increases, so that a high lubricating effect by the toner particles can be obtained.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view of a main part of the image forming apparatus according to the present embodiment. Since the entire configuration of the image forming apparatus according to the present embodiment is the same as that of the first embodiment, Description is omitted.

In this embodiment, the length of the multiple toner image 37 formed on the surface of the intermediate transfer member 4 is set to be longer than 外 周 of the outer peripheral length of the image carrier 1. Specifically, the length of the multiplex toner image 37 on the surface of the intermediate transfer member 4 is set to 65 mm, which is more than 1/2 = 62.83 mm (40π / 2) of the outer peripheral length of the image carrier 1. It is set long.

The joint top 3 in the joint 30 shown in FIG.
The maximum amount of phase shift between 2a and the image carrier shaft recess 1Js corresponds to less than 1/2 rotation of the image carrier 1. Accordingly, the maximum slip length at the contact portion between the image carrier 1 and the intermediate transfer member 4 is less than half of the outer peripheral length of the image carrier 1, and the length of the multiple toner image 37 on the surface of the intermediate transfer member 4 Are the image carrier 1 and the intermediate transfer member 4
Is longer than the maximum slip length at the contact portion, the toner particles are always present at the contact portion while the image carrier 1 and the intermediate transfer member 4 are slipping, so that the joint piece convex portion 32a is more reliably The image carrier shaft recess 1Js can be engaged.

In the above-described embodiment, a laser beam printer used as an image output terminal of an information processing device such as a computer has been described as an example of the image forming apparatus. However, the present invention is not limited to this. For example, a copy apparatus combined with a reader or the like or a facsimile apparatus having a transmission / reception function may be employed, and the same effects as described above can be obtained by applying the present invention to these apparatuses. .

In the above-described embodiment, a full-color image forming apparatus having four developing units has been described as an example. However, the present invention is not limited to this.
The same effect can be obtained by applying the present invention to an image forming apparatus having two or three developing units.

[0061]

As is apparent from the above description, claim 1
According to the described invention, since the toner image is formed on the image carrier during the initial operation before the printing operation, the image carrier and the intermediate transfer member slip at the contact portion by the lubricating action of the toner particles, When the coupling means is engaged, the driving force is transmitted to the image carrier to rotate the image carrier reliably, and abnormal rotation of the image carrier in the subsequent printing operation is prevented, and the occurrence of an abnormal image is effective. This has the effect of being effectively prevented.

According to the second aspect of the present invention, since the toner image is formed on the image carrier only when the image carrier is replaced, not every time during the initial operation, the frequency of forming the toner image is greatly increased. To reduce the amount of toner consumption.

According to the third aspect of the present invention, since multiple toner images are formed on the intermediate transfer member, the amount of toner increases upon arrival at the contact portion between the image carrier and the intermediate transfer member, and the toner particles are increased. High lubrication effect is obtained, the coupling means is securely engaged, the image carrier is more reliably driven to rotate, and the occurrence of abnormal images due to abnormal rotation of the image carrier in the subsequent printing operation is more reliable. Is obtained.

According to the fourth aspect of the present invention, since the circumferential length of the toner image formed on the intermediate transfer member is set to be at least half the outer peripheral length of the image carrier, the image carrier and the intermediate transfer member are set. During the slip, the toner particles are always present in the contact portion, and the coupling means is securely engaged, so that the image carrier is more reliably driven to rotate.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view of a joint (non-engaged state) of an image forming apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a partially enlarged view of a joint (engaged state) of the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a side sectional view showing a schematic configuration of the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 4 is a partially enlarged cross-sectional view of a main part of the image forming apparatus according to Embodiment 1 of the present invention.

FIG. 5 is a partial plan view of a main part of an image forming apparatus according to Embodiment 2 of the present invention.

FIG. 6 is a sectional view of a main part of an image forming apparatus according to Embodiment 3 of the present invention.

FIG. 7 is a sectional view of a main part of an image forming apparatus according to Embodiment 4 of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image carrier 1J image carrier shaft 1Js image carrier shaft recess 1U image carrier unit 2B, 3Y, 3M, 3C developing device 4 intermediate transfer member 27 black developing device guide 29 guide 30 coupling part (coupling means) 31 drive shaft 32 Joint top 32a Joint top 33 Joint pin 34 Joint spring 35 Detecting means 36 Toner image 37 Multiple toner image

Claims (4)

[Claims] An image forming section having an image carrier, a developing device, and an intermediate transfer body; attaching / detaching means for attaching / detaching the image carrier to / from a main body; and transmitting a driving force to the image carrier. And a joint means for forming a toner image on the image carrier during an initial operation before a printing operation. 2. A detecting means for detecting that the carrier is mounted on the main body, and forming a toner image on the image carrier when detecting that the image carrier is mounted on the apparatus main body. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to perform the operation. 3. The method according to claim 1, wherein the toner image formed on the image carrier is transferred onto the intermediate transfer member, and this is repeated a plurality of times to form a multiple toner image on the intermediate transfer member. The image forming apparatus according to claim 1. 4. The image forming apparatus according to claim 1, wherein a circumferential length of the toner image formed on the intermediate transfer body is set to be equal to or more than の of an outer circumferential length of the image carrier.