JPH07140868A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a fine grain passing through a cleaning unit from accumulating on an electrifying roller 2 and to eliminate problems caused in the case when passing fine grains are concentrated in the region of a part. CONSTITUTION:A second cleaning unit 5 is installed at the position downstream side of a normal cleaning unit 8 and the upstream side of an electrifying roller 2 and vibrated in the axial direction of a photoreceptor 1. Then, a holder 12 is engaged with the groove of a cam member 15 attached to the shaft of the photoreceptor 1 via an electromagnetic clutch 14, to drive the second cleaning unit 5. At the time of exposing an image and transferring, the electromagnetic clutch 14 is separated to inhibit the drive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a contact charging device that contacts a photoreceptor and charges it, and more particularly to cleaning of the photoreceptor.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus, a corona charger utilizing corona discharge has been generally used as a means for charging a photoconductor. However, in the case of a corona charger, ozone and nitrogen oxides are generated with corona discharge, and these are harmful to the human body and the environment. Further, these adhere to the photoconductor charger, the optical system, etc., and cause image deterioration.

In order to avoid such an inconvenience caused by corona discharge, a contact charging system in which a photoreceptor is directly contacted and charged is proposed in, for example, Japanese Patent Laid-Open No. 63-149668.

By adopting such a contact charging system, improvement in charging efficiency can be expected. However, in this method, since the charging member comes into contact with the photoconductor, fine powder toner (3 μm or less) on the photoconductor that passes through it without being captured by the cleaning device (for example, a cleaning blade) is located downstream of the cleaning device. Attached to the charging roller,
The surface of the charging roller becomes dirty, which causes charging failure.
There is a new problem.

In order to solve such a problem, for example, in JP-A-2-272582, JP-A-3-48870, and JP-A-3-101768, a newly installed cleaning member is always used as a charging member. There has been proposed a technique for removing dirt on a charging member by bringing them into contact with each other or separating them from each other.

[0006]

However, the conventional technique for removing dirt on the charging member by the cleaning member has a problem in durability of both the cleaning member and the charging member. That is, when dust, toner, and the like are accumulated between the cleaning member and the charging member, they become an abrasive and scrape the surface of the charging member.

Therefore, it is an object of the present invention to remove stains on the charging member to enable formation of a stain-free image and prevent wear and deterioration of the charging member for a long period of time.

[0008]

In order to solve the above-mentioned problems, in the present invention, a photosensitive member (1) for forming an image and a photosensitive member (1) which is configured to be in contact with the surface of the photosensitive member and charges the photosensitive member in a contact state. In an image forming apparatus provided with a contact charging member (11) and a first cleaning means (8) for removing toner and the like remaining on the photoconductor after the transfer of the image is completed: The second cleaning means (5), which is installed downstream of the first cleaning means and upstream of the contact charging member; and the second cleaning means, A drive means (1b, 12) for reciprocating in the axial direction of the member is provided.

According to a second aspect of the present invention, the drive inhibition control means (1) for controlling the drive means to inhibit the drive of the second cleaning means during the exposure operation of the photoconductor.
4, S1) is further provided.

In the invention of claim 3, the driving means is controlled so that the driving of the second cleaning means is prohibited during the transfer operation for transferring the toner image on the photoconductor onto the transfer paper. The drive inhibition control means (14, S2) is further provided.

The symbols shown in the above parentheses are the reference numerals of the corresponding elements in the embodiments described later, but each component of the present invention is a specific element in the embodiments. It is not limited to only.

[0012]

After the toner image is formed on the photoconductor (1) by performing the predetermined charging, exposing and developing processes, most of the toner image is transferred to the transfer paper by the transfer process. Then, stains such as toner and paper dust remaining on the photoconductor are removed by the first cleaning means (8) located downstream. However, the fine toner of 3 μm or less passes through it without being captured by the first cleaning means.
However, in the present invention, the second cleaning means (5) located downstream of the first cleaning means also removes the fine toner of 3 μm or less before reaching the contact charging member.

By the way, with respect to the leakage of the minute toner from the first cleaning means, there are generally a position where the leakage is easy and a position where the leakage is difficult. For example, due to the subtle unevenness of the contact pressure, there are places where residual particles that cannot be captured are concentrated, and at the position corresponding to the edge of the transfer paper, the amount of paper dust from the transfer paper is large, and the number of particles that cannot be captured also increases. . Therefore, particles such as toner leaking from the first cleaning means and captured by the second cleaning means tend to be concentrated in a part of the second cleaning means.

However, when the particles such as toner are concentrated on only a part of the second cleaning means, a part of the particles enter the gap between the second cleaning means and the photoconductor, and the second particles are affected by the particles. The particles may leak from the gap between the cleaning means and the photoconductor toward the contact charging member, may scratch the surface of the photoconductor, or cause abnormal wear. However, in the present invention, since the driving means (1b, 12) reciprocally drives the second cleaning means in the axial direction of the contact charging member, the second cleaning means moves relatively to the first cleaning means. However, the particles leaked from the first cleaning means are not concentrated on only a part of the second cleaning means.

Further, when the second cleaning means that comes into contact with the photoconductor is reciprocally moved in the axial direction, the effect of this vibration appears to the photoconductor or the like to some extent. Therefore, when the photosensitive member is exposed to the vibration or the image is transferred, the image may be disturbed. However, in the second aspect of the present invention, the driving of the second cleaning means is prohibited during the exposure operation of the photoconductor, so that the adverse effect of vibration does not occur when the electrostatic latent image is formed. Further, according to the third aspect of the invention, the driving of the second cleaning means is prohibited during the transfer operation, so that the image is not disturbed at the time of transfer.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of the peripheral portion of a photoconductor of an image forming apparatus of one type for carrying out the present invention. Referring to FIG. 1, a charging roller 2, a developing device 6, a transfer device 7, a first cleaning device 8, and a second cleaning device 5 are installed around the photoconductor 1. In this embodiment, the photoconductor 1
Rotates clockwise as indicated by the arrow.

The charging roller 2 is constructed by adhering a conductive rubber member having a low resistance to the circumference of a metal cored bar 11.
A voltage is applied to the charging roller 2 from a DC power supply 10 via a power supply receptacle (not shown) and a core metal 11. The voltage applied to the core metal 11 is a negative voltage of −500V, for example.

The charging roller 2 is in constant contact with the surface of the photoconductor 1. The contact pressure is 10 gf / cm in this example. The charging roller 2 rotates around the photosensitive member 1 that rotates in the direction of the arrow and rotates at a constant speed, and charges the surface of the photosensitive member with a voltage applied from the DC power supply 10.

In the image forming process, the surface of the photosensitive member 1 is uniformly charged by the charging roller 2, and then the charged surface of the photosensitive member 1 is exposed by light from an exposing device (not shown) to form an electrostatic latent image. To do. Subsequently, the developing device 6 causes toner to adhere to the electrostatic latent image to visualize the latent image. Next, the toner image on the photoconductor 1 is transferred by the transfer device 7 onto the transfer paper fed from the predetermined paper feed section through the paper guide 9 at the transfer entrance. After that, the toner remaining on the photoconductor 1 is removed by the first cleaning device 8. After that, the toner that cannot be completely removed by the first cleaning device 8 and the scattered toner and dust attached to the photoconductor 1 after passing through the first cleaning device 8 are removed by the second cleaning device 5.

In this example, the second cleaning device 5 is
The felt is constituted so as to be constantly in contact with the surface of the photosensitive member 1. In this example, the contact pressure is 10 gf / c.
It is set to m. In this example, the second cleaning device 5 is made of felt, but may be foamed polyurethane foam or polyurethane rubber.

In this embodiment, the second cleaning device 5
Are configured to reciprocate in the axial direction (width direction) of the photoconductor 1. The mechanism for driving the second cleaning device 5 is shown in FIG. As shown in FIG. 2, the flange 1a of the photoconductor 1 is provided with a groove cam 1b formed so as to draw a closed curve around the peripheral surface of the flange 1a. On the other hand, the felt, which is the second cleaning device 5, is fixed to the holder 12, and one end portion of the holder 12 is engaged with the groove cam 1b so as to function as a cam follower. .

Therefore, when the photoconductor 1 rotates, the holder 1
Since the position of the groove of the groove cam 1b with which 2 engages moves in the axial direction of the photoconductor 1, the movement of the position of the groove cam 1b
The holder 12 moves in the axial direction of the photoconductor 1. Groove cam 1b
Since the groove position moves back and forth for one cycle in the axial direction each time the photoconductor 1 makes one revolution, the holder 12 makes one reciprocation in the axial direction of the photoconductor 1 while the photoconductor 1 makes one revolution. It will work. Since the felt of the second cleaning device 5 is fixed to the holder 12, the felt moves reciprocally in the axial direction while coming into contact with the photoconductor as the holder 12 moves. The amount of felt movement is determined by the cam curve of the groove cam 1b. In this embodiment, the amount of movement of the felt is set to 10 mm.

Next, another embodiment will be described.
The basic structure of the apparatus is the same as that of the above-described embodiment, and also in this embodiment, the second cleaning device 5 is configured to reciprocate in the axial direction (width direction) of the photoconductor 1. The mechanism for driving the second cleaning device 5 is shown in FIG.

As shown in FIG. 3, one end of the photosensitive member 1 (of the rotating shaft) is connected to one end of the electromagnetic clutch 14,
A cam member 15 is fixed to the other end of the electromagnetic clutch 14. The cam member 15 is provided with a grooved cam 15a formed so as to draw a closed curve around the peripheral surface thereof.
On the other hand, the felt, which is the second cleaning device 5, is fixed to the holder 12, and one end portion of the holder 12 is engaged with the groove cam 15a so as to function as a cam follower. .

Therefore, when the photoconductor 1 rotates when the electromagnetic clutch 14 is on, the position of the groove of the groove cam 15a with which the holder 12 engages moves in the axial direction of the photoconductor 1, so that the groove cam 15a moves. The holder 12 moves in the axial direction of the photoconductor 1 according to the movement of the position. Since the groove position of the groove cam 15a reciprocates one cycle in the axial direction each time the photoconductor 1 makes one rotation, the holder 12 moves in the axial direction of the photoconductor 1 while the photoconductor 1 makes one rotation. It will make two round trips. The felt of the second cleaning device 5 is the holder 1
Since the holder 12 is fixed, the holder 12 is moved back and forth in the axial direction while coming into contact with the photoconductor as the holder 12 moves. However, when the electromagnetic clutch 14 is off, the cam member 15 remains stationary even if the photoconductor 1 rotates, so that the groove cam 15a.
Does not change, and the holder 12 and the second cleaning device 5 do not move.

The electromagnetic clutch 14 is on / off controlled by a system control unit (not shown) (for example, a microcomputer). A part of the processing of this system control unit is shown in FIG. The operation of the system control unit will be described with reference to FIG.

This system control unit manages the entire image forming process, counts the number of synchronization pulses output for each minute rotation of the photoconductor 1 driven at a constant speed, and determines the image forming process. Understand the time (elapsed time) since the start. Then, at each time point, the timing at that time is compared with various predetermined times (constants) to start and end the charging process, start and end the image exposure process,
Each process such as start and end of development process, start and end of transfer process, start and end of cleaning process is executed.

In step S0 of FIG. 5, it is discriminated whether or not it is time to start the image exposure process (actually, a time slightly before that time), and if YES, the process proceeds to step S1, otherwise to S3. move on. In step S3, it is identified whether or not it is the time to end the image exposure process (actually, a time slightly later than that). If YES, the process proceeds to step S4, and if not, the process proceeds to S5.

In step S1, the flag FC1 is cleared, and in step S4, the flag FC1 is set to 1.
Therefore, the flag FC1 is 0 from the start of the image exposure process to the end thereof. Otherwise, the flag FC1 is set to 1.

In step S5, it is discriminated whether or not it is the time to start the image transfer process (actually, a time slightly before that time). If YES, the process proceeds to step S2, and if not, to S6. In step S6, it is identified whether or not it is time to end the transfer process (actually, a time slightly later than that time). If YES, the process proceeds to step S7, and if not, to S8.

The flag FC2 is cleared in step S2, and 1 is set in the flag FC2 in step S4.
Therefore, the flag FC2 is 0 from the start of the transfer process to the end thereof. Otherwise, the flag FC2 is set to 1.

If both flags FC1 and FC2 are 1, the process proceeds to step SA through steps S8 and S9, and if not, the process proceeds from step S8 or S9 to step SB. In step SA, the electromagnetic clutch 14 is turned on, and in step SB, the electromagnetic clutch 14 is turned off.

That is, when neither the image exposure process nor the transfer process is executed, the electromagnetic clutch 14 is engaged in step SA, and when at least one of the image exposure process and the transfer process is executed, step S is executed.
At B, the connection of the electromagnetic clutch 14 is released.

FIG. 4 shows the timing of controlling the electromagnetic clutch 14 (an example in which three consecutive copies are obtained). As shown in FIG. 4, since the electromagnetic clutch 14 is turned off during exposure, the felt does not reciprocate. Also, since the electromagnetic clutch 14 is turned off during transfer, the felt does not reciprocate. When neither exposure nor transfer is performed, the electromagnetic clutch 14 is turned on and the felt 5 reciprocates.

[0035]

As described above, according to the present invention, the fine toner which could not be captured by the first cleaning means is the second cleaning means (5) located downstream of the fine toner.
By means of which it is removed before reaching the contact charging member. Moreover, since the driving means (1b, 12) reciprocally drives the second cleaning means in the axial direction of the contact charging member,
The cleaning means moves relative to the first cleaning means, and particles leaking from the first cleaning means do not concentrate on a part of the second cleaning means. Therefore, it is possible to prevent particles from leaking toward the contact charging member from the gap between the second cleaning means and the photoconductor, and to prevent the surface of the photoconductor from being scratched or abnormally worn.

According to the second aspect of the present invention, since the driving of the second cleaning unit is prohibited during the exposure operation of the photoconductor, it is possible to prevent the formation of the electrostatic latent image from being adversely affected.
Further, in the invention of claim 3, the second clear is performed during the transfer operation.
Since the driving of the steering means is prohibited, the disturbance of the image at the time of transfer can be prevented.

In any case, it is possible to prevent particles leaking from the cleaning step from accumulating on the contact charging member and causing charging failure.

[Brief description of drawings]

FIG. 1 is a front view showing a main part of an image forming apparatus according to an embodiment.

FIG. 2 is an enlarged side view showing a part of the device of FIG.

FIG. 3 is a side view showing a modified example of FIG.

FIG. 4 is a time chart showing electromagnetic clutch control.

FIG. 5 is a flow chart showing electromagnetic clutch control.

[Explanation of symbols]

1: Photoconductor 1a: Photoconductor flange 1b, 15a: Groove cam 2: Charging roller 5: Second cleaning device 6: Developing device 7: Transfer device 8: First cleaning device 9: Transfer entrance paper guide 11: Core 12 : Holder 14: Electromagnetic clutch 15: Cam member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kentaro Matsumoto 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Naoshi Hayakawa 1-chome, Nakamagome, Ota-ku, Tokyo No. 3-6 In Ricoh Company (72) Inventor Yoshiaki Miyashita 1-3-6 Nakamagome, Ota-ku, Tokyo (72) Inventor Ken Ken Tabuchi 1-chome Nakamagome, Ota-ku, Tokyo No. 6 in Ricoh Co., Ltd.

Claims (3)

[Claims] 1. A photoconductor for forming an image, a contact charging member configured to be in contact with a surface of the photoconductor and charging the photoconductor in a contact state, and a toner remaining on the photoconductor after the transfer of the image is completed. -In an image forming apparatus provided with a first cleaning unit for removing the: etc .: installed at a position downstream of the first cleaning unit and upstream of the contact charging member in the moving direction of the photoconductor. An image forming apparatus comprising: a second cleaning unit; and a driving unit that reciprocally drives the second cleaning unit in the axial direction of the contact charging member. 2. The image according to claim 1, further comprising drive inhibition control means for controlling the drive means to inhibit the drive of the second cleaning means during the exposure operation of the photoconductor. Forming equipment. 3. A drive prohibition control means for controlling the drive means to prohibit the drive of the second cleaning means during a transfer operation for transferring the toner image on the photoconductor onto a transfer sheet. The image forming apparatus according to claim 1, further comprising: