JPH0756422A - Electrifier for image forming device - Google Patents

Abstract

PURPOSE:To easily revers a cleaning member while surely covering an image region at a low cost by providing a switching means changing over the driving member of the cleaning member from a first engaging position where it is engaged with a means driven with a drive source to a second engaging position. CONSTITUTION:A bar body 26a2 is engaged with an engaging pawl 29th disposed on the upper part of a driving part and the cleaning member 26 moves while being slid to clean an electrifying wire 25 via the bar body 26a2, in accordance with the movement of the driving part. Then, a mobile member 29m is provided on the lower side of the driving part, supports the engaging pawl 29h simultaneously, is connected to a driving block 29a so as to freely rock with respect to the mobile member 29m. Moreover, the mobile member 29m is engaged with the edge part of the slit of the bottom part of a rail member 28 and guided to moved in this state. In other words, the switching means changing over a driving means from one engaging position to the other engaging position is provided.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer.
In particular, it relates to the charging device.

[0002]

In the known image forming apparatus as described above, when the surface of the image bearing member is uniformly charged for electrostatic latent image formation, it is formed on the image bearing member. When a toner image is transferred onto a transfer material, or when the transfer material is separated from the image carrier after the transfer, a corona discharger (referred to as a charger) is widely used.

This type of charging device usually has a structure in which a charging wire is extended in a shield case that is open to the surface to be charged. On the other hand, in the image forming apparatus, from the toner image itself, In addition, it is inevitable that toner leaked from open parts such as developing devices and cleaning devices, fine paper powder generated from paper that is frequently used as a transfer material, precipitates such as rosin and talc, and dust are present in a floating state. So
These foreign matters adhere to the charging wire of the charger and cause uneven charging,
There is a possibility that charging failure may occur, resulting in deterioration of image quality.

In order to avoid such a problem, a cleaning member for sandwiching the charging wire is provided in the charger, and the cleaning member for sandwiching the charging wire is moved by a separate drive means to clean it when necessary. Cleaning means have been proposed.

FIG. 13 shows an example of driving means for moving a known cleaning member, which will be briefly described below. The figure shows only the drive part in the vicinity of the transfer part of the image forming apparatus with the transfer charger removed, and the transfer material (not shown) that advances from the right side in the figure in the direction of the white arrow Transfer is performed through the position of the charger, and then the transport path 1
It is assumed that this is also conveyed to the fixing portion (not shown) along the line 8.

A rail member 28 is arranged at the upstream end of the conveying path 18 so as to be orthogonal to it, and a screw rod 29b is arranged below the rail member 28 in parallel therewith. There is. A drive unit 29 is arranged in the rail member 28, and a drive block 29a arranged below the drive unit 29 is screwed into the screw rod 29b through an elongated hole 28c provided at the bottom of the rail member 28. I am fit.

The drive shaft of a motor 29d disposed near one end of the rail member is engaged with a gear 29c at the end of the screw rod 29b, and the screw rod 29b is rotated by the motor 29d. The drive unit 29 travels in the front-rear direction inside the rail member 28 together with the block 29a.

An engaging claw 29h, which is urged to rotate clockwise by a spring 31 and abuts against the stopper 33a, is provided on the upper portion of the drive unit 29, near the cleaning member (not shown). engagement pawl to 29h is provided with a resilient disengaging portion 29h _2, extending from the cleaning member in the recess 29h ₂ downward, which is formed between the engagement claw 29h tip door and shelf surname engaging and disengaging portion It is assumed that an existing rod (not shown) is engaged. Therefore, as described above, the drive unit 2 is rotated by the rotation of the screw rod.
When 9 moves, a cleaning member (not shown) travels inside the rail member 28 by the engagement between the engaging claw and the rod body to clean the wire of the sleeping charger.

Numerals 29g and 29f shown in the figure are microswitches for detecting the traveling end of the drive unit 29 and controlling the movement thereof. Further, as the position control of the drive unit, other than this, it is possible to detect and control that the drive unit is at the end portion of the traveling stroke according to the traveling time of the drive unit. Further, as shown in FIG. 14, the screw rod 2
A means is conceivable in which the lead of 9 is continuous so as to be folded back at the end and the drive unit is reversed along this.

At the same time, the above-mentioned means using the microswitch leads to an increase in the size of the mechanism and an increase in cost, and the time-controlled method is to be cleaned by the load applied to the drive section by the cleaning means. There is a risk that the amount of movement of the member is unavoidably changed and cleaning of the image area, especially both ends thereof, may be lacking. Further, as described above, the lead portion of the screw rod is configured so that the spiral groove and the protrusion on the driving portion side engaging with the groove are formed when the driving portion travels in one direction and in the opposite direction. Since it is unavoidable that there is backlash between the drive unit and the drive section, it becomes difficult to perform high-precision cleaning on the image area, and it is necessary to keep the moving range of the drive section wide and avoid enlargement of the device. Absent.

The present invention has been made in view of the above circumstances, and in an image forming apparatus using a charger,
It is an object of the present invention to provide a charging device that can perform traveling and reversal of a cleaning member of the charging device with high accuracy and low cost.

[0012]

[Constitution of the invention]

In order to achieve the above object, the present invention provides a cleaning member for tensioning a charging wire inside and for cleaning while reciprocating by holding the charging wire. The charging device of the image forming apparatus having means for driving the cleaning member, is provided with a switching means for switching from one engagement position to the drive means to another engagement position at the end of the reciprocating movement of the cleaning member. Alternatively, in the above device, the switching means is composed of a fixed member in a stationary portion near the end of reciprocating movement and a movable member provided in the driving means and engaged with and disengaged from the fixed member, or The means for applying the driving force may be a screw rod having two sets of thread grooves formed in opposite directions, or the means for applying the driving force to the driving means may have a large number of tooth-shaped projections on the inner surface. Provide A charging device characterized by comprising an endless belt.

With this configuration, the reversal of the reciprocating cleaning member can be performed easily and at low cost while surely covering the image area.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS "FIG. 1" is a schematic side view schematically showing the structure of a portion near a sleeping image carrier of an image forming apparatus to which a charging device according to the present invention is applied, and extends in a direction perpendicular to the plane of the drawing. The surface photosensitive layer of the image carrier 12 is uniformly charged by the primary charger 13, and the similar image signal L is projected to form an electrostatic latent image.

This latent image is provided with a toner image at the developing portion where the developing device 14 is arranged, and becomes a toner image. When the toner image reaches the transfer portion where the transfer charger 15 is arranged, the transfer material (not shown) supplied from the conveying path 17 reaches the transfer portion and is applied to the transfer charger together with the transfer material. By the transfer bias thus generated, the toner image on the image carrier side is transferred to the transfer material. Next, the transfer material is separated from the image carrier, and is discharged to the outside of the apparatus via the conveyance path 18 and a fixing portion (not shown). Residual toner that has not transferred to the transfer material at the transfer site is removed by the cleaning device 16, and the image carrier is ready for the next image forming step. In such a device, although not shown,
The transfer charger 15 is provided with a cleaning member for running in the transfer charger in a longitudinal direction (a direction perpendicular to the paper surface) in order to clean the charging wire stretched on the transfer charger 15.

FIG. 2 shows a charger 15 arranged in parallel with and close to the image carrier 12 and a drive unit 29 arranged below the charger 15.
FIG. 3 is a perspective view showing only the driving part with the charger portion removed. The structure of the portion shown in "FIG. 3" is basically the same as that shown in "FIG. 13" described above.
Corresponding parts are designated by the same reference numerals and will not be described unless necessary.

FIG. 2 shows a transfer charger 1 equipped with a cleaning member.
5 is a cross-sectional view showing a relational configuration between 5 and a drive unit 29 that causes the cleaning member to travel (in a direction perpendicular to the paper surface in the figure).
A rail member 28 is provided in the vicinity of the image carrier 12 that extends in the direction perpendicular to the plane of the drawing.
A charging device 15 including the above is provided. In the illustrated case, three charging wires 25 are arranged in the shield case 27, and each charging wire is provided on a cleaning member 26 which is movable in the longitudinal direction of the charger (perpendicular to the paper surface). It is also sandwiched by elastic pads 26b arranged inside the arm 26a ₁ . Each of the arms 26a ₁ projects downward in the drawing from an opening at the bottom of the shield case 27,
A rod body 26a ₂ is provided at this portion.

[0018] The rod body 26a ₂ is engaged with the engaging claw is disposed on top of the drive unit 29 shown in "Figure 3" 29h, as movement of the drive unit 29, via the rod 26a ₂ The cleaning member 26 moves while rubbing and cleaning the charging wire 25.

As shown in FIG. 6, a moving member 29m is provided below the drive unit 29. The moving member 29m supports the engaging claw 29h and the moving member 29m.
It is connected to a drive block 29a that can swing with respect to m. The moving member 29m engages with the edge of the slit 28c at the bottom of the rail member 28 and is guided and moved by the edge. That is, the moving member 29m is movably guided to the slit edge of the rail member 28, and the engaging claw 29h located on the upper portion thereof and biased to one side by the spring 31 grips the rod body 26a ₂ of the cleaning member 26. Therefore, the moving member 29m is engaged with the drive block 29a that is engaged with and disengaged from the screw rod 29b.

As shown in FIG. 3, the screw rod 29b that engages with the drive portion 29 and travels the drive portion 29 has independent spiral grooves in the opposite left and right directions in the illustrated case. From the moving member 29m of the drive unit 29, the rod 29m ₁
Is extended, and the drive block 2 is attached to the rod 29m _1.
9a is rotatably arranged. Further, the driving block 29a has a forked shape as seen from above as shown in FIGS. 7 and 8 to form legs 29a ₅ and 29a _6, and holes formed in the base thereof. 29a ₈ is the rod 29m
₁ is loosely fitted. Further, each leg of the drive block 29a is provided with projections 29l ₅ and 29l _{6 at} a portion facing the screw rod 29b so as to engage with each spiral groove of the screw rod. Therefore, as shown, the drive block 29
a is the swung around rod 29m _1, wherein the protrusion of one of the legs is able to engage the spiral groove of the corresponding side of the threaded rod 29b.

The leg 29a ₅ has an engaging end 2
9a ₉ and 29a ₁₀ are formed, and fixed engaging claws 51 and 52 are arranged at positions in contact with the engaging ends at appropriate positions near both ends of the screw rod 29b of the immovable portion of the image forming apparatus main body. It is set up.

For example, as shown in FIG. 7, the projection 29l ₅ of one leg 29a ₅ of the drive block 29a is screwed into one screw groove of the screw rod 29b to move from left to right in the figure. When it advances and reaches a predetermined position, the engaging end 29a _{9 of} the leg 29a ₅ collides with the fixed engaging claw 51 and rotates counterclockwise in the drawing to separate from the screw groove, and projection 29l ₆ of the leg 29a ₆ is engaged with the other of the thread groove. Therefore, if the screw rod 29b is rotated as it is, the drive block 29a advances to the left in the drawing. In accordance with the reciprocating movement of the drive block 29a, the charging member 26 formed integrally with the drive block 29a grips and rubs the charging wire.

When the drive block 29a reaches a predetermined position on the opposite side shown in FIG. 8, the leg portion 29a ₅ comes into contact with the fixed engagement claw 52 and the drive block 29a rotates clockwise to cause the leg portion 29a. ₆ disengages from the thread groove, and with this, leg 2
9a ₆ comes into contact with the microswitch 29f and turns it off, stopping the motor and stopping the cleaning. A protrusion 29m ₂ is formed on the rod 29m ₁ , which is a recess 29s formed in the hole on the drive block side.
_1, fitted to one of 29m _2, threaded rod 2 of each leg portion
The engagement with 9b is ensured.

With such a structure, it is not necessary to reversely rotate the motor to reciprocate the cleaning member, and the fixed engaging claws 51 and 52 may be attached to the rail member at appropriate positions. It is possible to determine the reversal position with respect to the image region with higher accuracy, as compared with the case where the thread groove ends of the screw rod are connected endlessly.

Next, the control of the drive unit will be described. “FIG. 4” is a block diagram of the control means, and the control means 30
Includes a ROM 30b that stores the control contents of the entire image forming apparatus including the drive unit 29, a RAM 30c that is used as a work area of the CPU 30a and temporarily stores various data, and an interface 30d. On the output side of the interface 30d, a light source, a reading system (not shown) such as a mirror and a mirror, a primary charger 1
3, a developing device 14, a transfer charger 15, a pickup roller for taking out the transfer material from the cassette, a carrying roller (not shown) for carrying the same, a carrying path 18, etc. are connected.

When the cleaning operation start signal is output by the control system 30, as shown in the flow chart of FIG.
First, the screw rod 29b is rotated by the motor 29d (step S1). As a result, the drive block 29a is guided by the rail member 28 and travels from the Y end to the X end in FIG. 3, and the cleaning member 26 connects the charging wire 25 by connecting the engaging claw 29h and the rod body 26a _2. Hold it and clean it.

When the drive unit 29 moves together with the cleaning member 26 and reaches the X end, the drive unit 29 reverses in the above-described manner and advances toward the Y end, and at the moving end thereof, the Y end. Micro switch 29f is actuated when it reaches (step S
2) Then, the motor is stopped (step S3) to finish the cleaning.

FIG. 9 and FIG. 10 are perspective views and a side view of essential parts showing only the driving device portion of the cleaning member, showing another embodiment. A motor 29 is provided below the rail member 28.
The endless belt 15 is provided between the pulley 155 attached to the output shaft of d and the pulley 156 arranged on the opposite side in the longitudinal direction of the charger.
1 is on display.

A drive block 29'a provided below the drive unit 29 that is guided by the rail member 28 is disposed so as to surround the belt 151, and an engagement / disengagement member 160 is provided in the inner hollow portion thereof. (See FIG. 11) is provided.
The engaging / disengaging member 160 is an engaging claw 29 for engaging the cleaning member 26.
It is swingably disposed on a rod 29'm extending below h, and both ends thereof are formed at engaging ends 160a and 160b.

The belt 151 has a structure in which a large number of strong tooth-shaped protrusions are provided in a row inside the belt 151. The pulleys 155 and 156 at both ends of the belt 151 are engaged with the engaging ends at appropriate positions. Fixed engagement claws 159 and 161 (FIG. 12) for disengaging are provided.

As shown in FIG. 11, the engagement / disengagement member 160
Is displaced upward in the drawing and meshes with the teeth of the upper belt to run in the direction of the arrow, the drive block 29'a and the cleaning member 26 connected to this drive block 29'a move to the right in the drawing to move the charging wire. Is cleaned.

When the drive block 29'a reaches the end of the stroke, the engaging end 160a of the engagement / disengagement member 160 contacts the fixed engagement claw 159 to rotate the engagement / disengagement member 160 clockwise. Lever 151 engages with the tooth-shaped projection below the belt 151, and thereafter the drive block, and hence the cleaning member 26, runs in reverse. When the drive block reaches the opposite end of the stroke, the engagement / disengagement member 16
The engagement engagement end 160b of 0 engages with the fixed engagement claw 161 and the cleaning member is inverted again.

In this case, when to operate the cleaning member,
It can be easily understood that whether to stop the operation can be appropriately set by the control means (not shown). With this configuration, the drive mechanism for the charging wire cleaning member can be downsized and simplified. Further, the case where the present invention is applied to the transfer charger has been described above.
Of course, the present invention is not limited to this, and can be applied to a primary charger and other chargers.

[0034]

As described above, according to the present invention, when cleaning the charging wire of the charger used for the image carrier, when the cleaning member is reciprocated along the charging wire, the driving member of the cleaning member is used. Is provided with switching means for switching from a first engagement position in which the means is driven by a drive source to a second engagement position, whereby the cleaning member is reversed, so that the cleaning member is moved. The reversing mechanism can be made as small and simple as possible, the reversing position can be determined with high precision, and complicated motor control is not required, so only the charging wire portion corresponding to the entire image area can be cleaned with high precision at low cost. It is possible. Further, it is possible to preferably avoid that the driving member travels excessively and the motor is overloaded due to a failure of the detection means such as the micro switch.

[Brief description of drawings]

FIG. 1 is a schematic side view showing the configuration of an image carrier, Kinwa Uno, of an image forming apparatus to which the present invention is applied.

FIG. 2 is an enlarged cross-sectional view showing the image carrier and a transfer charger facing the same.

FIG. 3 is a perspective view showing a configuration of a drive portion of the cleaning member of the above.

FIG. 4 is a block diagram of control means for the entire apparatus including a drive unit.

FIG. 5 is a flowchart showing the operation of the cleaning member drive unit.

FIG. 6 is a side view of an essential part showing the relative arrangement of a cleaning member and a drive unit connected to the same.

FIG. 7 and

FIG. 8 is an explanatory diagram showing a reversing operation of a driving unit.

FIG. 9 is a perspective view showing a cleaning member drive unit according to another embodiment.

FIG. 10 is a side view of the main part of the same as above.

FIG. 11 and

FIG. 12 is a side view showing a reversing mechanism section of the driving section.

FIG. 13 is a perspective view showing a known cleaning member drive mechanism.

FIG. 14 is a plan view of an essential part of a screw rod for driving the same as above.

[Explanation of symbols]

 12 image carrier 15 transfer charger 26 cleaning member 28 rail member 29 driving member 29a driving block 29b screw rod 29d motor 29g micro switch 29m moving member 51, 52 fixed engaging claw 151 endless belt 155, 156 pulley 159, 161 fixing member Synthetic claw 160 Engaging member

Claims (4)

[Claims] 1. A charging device for an image forming apparatus, comprising: a charging wire extending inside; and a cleaning member that holds the charging wire and cleans it while reciprocating while driving the cleaning member. A charging device comprising switching means for switching the cleaning member from one engaging position to the other engaging position to the driving means at the end of reciprocating movement. 2. A charging device in which the switching means is composed of a fixed member in a stationary portion near the end of reciprocating movement and a movable member provided in the driving means and engaged with and disengaged from the fixed member. 3. The device according to claim 1, wherein the means for applying a driving force to the driving means comprises a threaded rod having two sets of thread grooves formed in opposite directions. Charging device. 4. The charging device according to claim 1, wherein the means for applying a driving force to the driving means comprises an endless belt having a large number of tooth-shaped projections on its inner surface.