JP2002365878A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device which can carry out the changeover of developing units at a high speed without causing the increase of the cost. SOLUTION: The developing device to develop an electrostatic latent image formed on a photoreceptor drum 1 with toner is characterized in what it possesses several developing units 4Y-4Bk, a holding member 4 to hold the several developing units 4Y-4Bk, a stepping motor 4e to rotate the holding member 4 and the motor 4h of the stepping motor 4e to apply auxiliary force in the rotating direction of the holding member 4 at the time of accelerating the rotation of the holding member 4 and to apply the auxiliary force in the direction reverse to the rotating direction of the holding member 4 at the time of decelerating the rotation of the holding member 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for developing an electrostatic latent image formed on an image carrier with a selected developing device by rotating a plurality of developing devices held by a holding member. The present invention relates to a developing device.

[0002]

2. Description of the Related Art An example of a conventional developing device will be described with reference to the drawings. FIG. 6 shows Y (yellow), M (magenta),
A holding member 104 for holding a developing device containing toner of each color of C (cyan) and Bk (black) is rotated to a predetermined developing position about a shaft 104d by a motor 104e, and is formed on the photosensitive drum 101. FIG. 2 is a diagram illustrating a part of a color laser printer that develops an electrostatic latent image with toner.

[0003] As a driving means for switching the developing device,
A stepping motor 104e is used. The driving force of the stepping motor 104e is the gear 1 coupled to the motor shaft.
04f through the idle gear 104g, the developing device holding member 104
Is transmitted to the large-diameter gear 104A which also serves as the side plate of. After the initial position is determined, the motor 10
4e. That is, when developing a certain color, the holding member 104 and the developing device are stopped by the holding torque of the stepping motor 104e, and when switching the developing device, the developing device of the next color is installed at the developing position. Thus, the stepping motor 104e is driven to rotate by the number of rotation steps, and is again held by the holding torque of the stepping motor 104e.

In this type of color laser printer, it is necessary to rotate the holding member 104 by a predetermined angle in order to switch the developing device for each color development. Therefore, it is necessary to switch the developing device in a short time in order to speed up image formation. There is a method of changing the motor to one having a large power in order to switch the developing device in a short time.

[0005]

However, this method not only increases the size of the apparatus but also increases the cost, and is disadvantageous for developing a low-cost color image forming apparatus.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device capable of switching developing units at high speed without increasing costs.

[0007]

In order to solve the above-mentioned problems, a typical configuration of a developing device according to the present invention is a developing device for developing an electrostatic latent image formed on an image carrier with toner. A plurality of developing devices, a holding member that holds the plurality of developing devices, a driving unit that rotates the holding member,
And an auxiliary unit of the driving unit that applies an auxiliary force in the rotation direction of the holding member when the rotation of the holding member is accelerated, and applies an auxiliary force in the reverse rotation direction of the holding member when the rotation of the holding member is decelerated. Features.

[0008]

[First Embodiment] An embodiment of a developing device according to the present invention will be described with reference to the drawings. FIG.
Is an application of the developing device according to the present invention to a four-color full-color laser beam printer. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Description of the whole image forming apparatus) First, the configuration of the whole image forming apparatus will be described.

In the image forming apparatus shown in FIG. 1, the images developed for each color in the image forming units (1, 3, 4) are primary-transferred to an intermediate transfer unit 5 and conveyed by a feeding / conveying system 7. The secondary transfer is collectively performed on the transfer material S. afterwards,
The transfer material S is conveyed to the fixing device 8 by the conveying means 12, where the toner image is fixed, conveyed on the conveyance path 15 by the conveyance rollers 13 and 16, discharged to the discharge tray 10 outside the main body by the discharge roller 9, and stacked. Is done.

The details of each section will be described in detail below.

(Developing Apparatus) The developing apparatus includes a developing device holding member 4 rotatable around a shaft 4d, and four developing devices 4Y, 4M, 4C, and 4Bk mounted on the holding member. At the time of developing the electrostatic latent image on the photosensitive drum 1, the holding members 4 are rotated by the motor 4e, whereby the respective color developing devices are arranged at predetermined developing positions, and the developing sleeve 4b of the developing device is further moved to the photosensitive drum. Then, the electrostatic latent image on the photosensitive drum 1 is developed.

This development is performed as follows. A developing sleeve 4b that rotates by an application roller 4a that rotates the toner corresponding to the color to be developed and a toner regulating blade 4c.
And apply a charge to the toner. By applying a developing bias between the developing sleeve 4b and the photosensitive drum 1 on which the electrostatic latent image is formed, toner can be attached to the electrostatic latent image and developed as a toner image.

(Photosensitive Drum) The photosensitive drum 1 is formed by coating an organic photoconductive layer on the outer peripheral surface, and supports both ends thereof, and obtains driving force from a motor at one end. Is driven to rotate.

(Charging device) The charging device 2 is disclosed in JP-A-63-1
Use is made of a contact charging system as shown in Japanese Patent No. 49669. As a method, a conductive roller formed in a roller shape is brought into contact with the photosensitive drum 1 and a charging bias voltage is applied to the roller to uniformly charge the surface of the photosensitive drum.

(Scanner Unit) The scanner unit 3 irradiates the polygon mirror 3a with image light corresponding to an image signal by a laser diode. The polygon mirror 3a is configured to rotate at high speed and selectively expose the surface of the charged photosensitive drum 1 to the reflected image light via the imaging lens 3b, the reflection mirror 3c, and the like to form an electrostatic latent image. Have been.

(Intermediate Transfer Unit) The intermediate transfer unit 5 sequentially and secondarily transfers the toner images, which have been primary-transferred and superimposed, sequentially from the photosensitive drum 1 to the transfer material S in a lump. The intermediate transfer section 5 has an intermediate transfer belt 5a running in the direction of arrow R5.
It is an endless belt of 40 mm and is stretched around three rollers of a driving roller 5b and driven rollers 5c and 5d. Further, a cleaning unit 5e is provided at a predetermined position outside the intermediate transfer belt 5a to remove transfer residual toner remaining on the intermediate transfer belt after the toner image is secondarily transferred by the secondary transfer unit 11. . The cleaning unit 5e contacts the charging roller 5f with the intermediate transfer belt 5a to apply the opposite charge to the toner at the time of transfer. The oppositely charged toner is electrostatically attached to the photosensitive drum 1 and thereafter collected by a cleaning device 6 for the photosensitive drum 1 to be described later.

(Cleaning device) Cleaning device 6
After the toner developed on the photosensitive drum 1 by the developing device is primary-transferred to the intermediate transfer belt 5a, the transfer residual toner which is not primary-transferred and remains on the surface of the photosensitive drum 1 is removed. . The transfer residual toner is accumulated in the cleaning container, and is replaced when it becomes full.

(Supply / Conveying Means) The feeding / conveying means 7 conveys the transfer material S to the image forming section, and includes a feeding cassette 7a in which a plurality of transfer materials S are stored. At the time of image formation, the pickup member 7e and the conveying roller 7b are driven and rotated in accordance with the image forming operation to separate and feed the transfer material S in the feeding cassette 7a one by one, and to guide the transfer material S by the guide plate 7c, The sheet is fed to the intermediate transfer belt 5a through 7d.

(Fixing Device) The fixing device 8 fixes a plurality of toner images secondary-transferred onto the transfer material S. The fixing device 8 applies heat and pressure to the driving and rotating drive roller 8a and the transfer material S pressed against the same. And a fixing roller 8b for applying the pressure. That is, the transfer material S, which has passed through the secondary transfer roller for collectively transferring the toner on the intermediate transfer belt 5a, is conveyed by the drive roller 8a when passing through the fixing device 8, and heat and pressure are applied by the fixing roller 8b. Thus, a plurality of color toner images are fixed on the surface of the transfer material S.

(Image forming operation) The photosensitive drum 1 is rotated in the direction of the arrow in synchronization with the rotation of the intermediate transfer belt 5a, and the surface of the photosensitive drum 1 is uniformly charged by the charging device 2 and is exposed by the exposure means 3. Light irradiation of a yellow image is performed to form a yellow electrostatic latent image on the photosensitive drum 1. At the same time as the formation of the electrostatic latent image, the developing device is rotated to arrange the yellow developing unit 4Y at the developing position, and the photosensitive drum 1 is moved so that the yellow toner adheres to the electrostatic latent image on the photosensitive drum 1. A voltage having the same polarity as the charging polarity and substantially the same potential is applied to cause the yellow toner to adhere to the electrostatic latent image for development. By applying a voltage having a characteristic opposite to that of the toner to the primary transfer roller 5j, the yellow toner image on the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 5a.

When the primary transfer of the yellow toner image is completed as described above, the next developing unit rotates and is positioned at the developing position opposite to the photosensitive drum 1, and each color and static image are transferred in the same manner as in the case of yellow. The formation, development, and primary transfer of an electrostatic latent image are sequentially performed, and four color toner images are superimposed on the intermediate transfer belt 5a. These toner images are collectively and secondarily transferred onto the transfer material S supplied from the feeding / conveying means 7.

The transfer material S after the secondary transfer is conveyed to the fixing device 8 by the conveying means 12, where the toner image is fixed, and then conveyed on the conveying path 15 by the conveying rollers 13 and 16, and is discharged by the discharge roller 9. The sheet is discharged and stacked on the discharge tray 10 outside the main body, and the formation is completed.

Hereinafter, the structure of the developing device of the present invention will be described with reference to FIGS.

As shown in FIG. 2, in this embodiment, a stepping motor 4 is used as a driving means for switching the developing device.
e is used. The driving force of the stepping motor 4e is the gear 4f coupled to the shaft of the stepping motor 4e.
Is transmitted to a large-diameter gear 4A also serving as a side plate of the developing device holding member 4 via an idle gear 4g. Further, a small motor 4h is used as an auxiliary means of the driving means. The auxiliary force of the small motor 4h is transmitted from a gear 4i coupled to the shaft of the small motor 4h to a large-diameter gear 4A also serving as a side plate of the developing device holding member 4.

The switching operation of the developing device is performed by the developing device holding member 4 being sequentially driven by a stepping motor 4e in the order of acceleration rotation, constant speed rotation, and deceleration rotation. When the motor 4h is driven in the rotational direction when the motor 4h is driven to accelerate, the motor 4h is driven in the reverse direction when the motor 4h is driven to rotate in a decelerated manner. ), And the stepping motor 4e is assisted.

Normally, the acceleration / deceleration control of the stepping motor 4e can be calculated based on the total moment of inertia at the axis of the stepping motor 4e, load torque, required switching time, torque characteristics of the stepping motor 4e, and the like. When the stepping motor 4e is assisted by the motor 4h, the rotational drive cannot be performed well by the acceleration / deceleration control calculated before the assistance. In this case, the torque of the motor 4h is added to the torque characteristic of the stepping motor 4e,
When the acceleration / deceleration control of the stepping motor 4e is performed, the drive can be performed well.

The driving means is a stepping motor 4
Although described using e, the present invention is not limited to this, and a DC servomotor may be used.

As described above, when the developing device is switched, the developing device 4Y
By applying an assisting force in the rotation direction of the holding member 4 when the rotation of the holding member 4 is accelerated by up to 4Bk and applying an assisting force in the reverse rotation direction of the holding member 4 when the rotation of the holding member 4 is decelerated, the cost of the developing device is increased It can be rotated at high speed without the need.

[Other Embodiments] Next, another embodiment of the developing device according to the present invention will be described with reference to the drawings. The same parts as those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted. 3 to 5 show other embodiments.

In the present embodiment, as shown in FIG.
As the auxiliary means of the driving means, a cam mechanism including a cam 4j and a bar 4k (hereinafter referred to as a follower) which moves up and down according to the shape of the cam 4j is used instead of the motor 4h of FIG. The cam 4j is fixed to the holding member 4. The follower 4k has a force F1 by a spring (not shown).
To the cam 4j, whereby energy is stored in the cam mechanism. Also, followers 4k
A roller 41 is attached to the tip of the roller to reduce friction.

When the developing device is at the developing position, the cam 4j
Since the tangent line of the cam 4j at the point where the roller 4l comes into contact with the roller 4l and the line parallel to the moving direction of the follower 4k are perpendicular to each other, no assisting force is applied in the rotation direction or the reverse rotation direction of the developing device. When the developing device starts rotating and accelerating, the tangent line of the cam 4j and the moving direction R4k of the follower 4k as shown in FIG.
The energy stored in accordance with the angle α of the line parallel to is released, a force F2 is applied in the same direction as the rotation direction of the developing unit, and the stepping motor 4 serving as a driving unit of the developing unit is released.
e. Also, when the developing device starts rotating and decelerating,
As shown in FIG. 5, energy is stored in the cam mechanism in accordance with the magnitude of the angle α, and a force F2 is applied in a direction opposite to the rotation direction of the developing device.
And this also assists the stepping motor 4e which is a driving unit of the developing device.

Further, the position of the developing device is stopped at a position other than the predetermined developing position as shown in FIGS. 4 and 5, such as immediately after the power is turned on, and it is necessary to move the developing device to the predetermined developing position shown in FIG. At this time, the stepping motor 4e must be driven against the force F2 in the reverse rotation direction by the cam mechanism. In this case, when trying to perform normal driving, the force F2
And the stepping motor 4e may stop. This can be solved by driving the stepping motor 4e at a strong low speed.

As described above, when the developing device is switched, the developing device 4Y
By applying an assisting force in the rotation direction of the holding member 4 when the rotation of the holding member 4 is accelerated by up to 4Bk and applying an assisting force in the reverse rotation direction of the holding member 4 when the rotation of the holding member 4 is decelerated, the cost of the developing device is increased. It can be rotated at high speed without any.

[0035]

As described above, according to the present invention,
When the rotation of the holding member of the developing device is accelerated during the switching of the developing device, an assisting force is applied in the rotation direction of the holding member, and when the rotation of the holding member is decelerated, the assisting force is applied in the reverse rotation direction of the holding member, thereby increasing the cost of the developing device. It can be rotated at high speed without the need.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration of an auxiliary unit of a driving unit.

FIG. 3 is a diagram illustrating a configuration of an auxiliary unit of a driving unit according to another embodiment.

FIG. 4 is a diagram showing a configuration of auxiliary means of the driving means.

FIG. 5 is a diagram showing a configuration of auxiliary means of the driving means.

FIG. 6 is a diagram illustrating a configuration of a conventional developing device.

[Explanation of symbols]

 F1, F2 ... force S ... transfer material 1 ... photosensitive drum 2 ... charging device 3 ... scanner unit 3a ... polygon mirror 3b ... imaging lens 3c ... reflection mirror 4 ... holding member 4A ... gears 4Y to 4Bk ... developing device 4a ... Coating roller 4b Developing sleeve 4c Toner regulating blade 4d Shaft 4e Stepping motor 4f Gear 4g Idling gear 4h Motor 4i Gear 5 Intermediate transfer unit 5a Intermediate transfer belt 5b Driving roller 5c Driven roller 5d .. Follower roller 5e. Cleaning unit 5f... Charging roller 5j. Fixing device 8a: driving roller 8b: fixing roller 9 discharge roller 10 discharge tray 11 secondary transfer means 12 transfer means 13 transfer roller 15 transfer path 16 transfer roller

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H030 AA06 BB24 BB33 2H077 AD06 BA01 BA04 DB18 EA11 EA16 FA21 GA13 5H571 AA13 BB06 FF01 5H580 AA04 AA05 AA07 BB09 FC01 HH31

Claims (9)

[Claims] 1. A developing device for developing an electrostatic latent image formed on an image carrier with toner, comprising: a plurality of developing units; a holding member for holding the plurality of developing units; and rotating the holding member. A driving unit for causing the holding unit to apply an assisting force in the rotation direction of the holding member when the rotation of the holding member is accelerated, and an auxiliary unit for the driving unit to apply an assisting force in the reverse rotation direction of the holding member when the rotation of the holding member is decelerated. And a developing device. 2. The developing device according to claim 1, wherein said auxiliary means is a motor. 3. The developing device according to claim 1, wherein said auxiliary means is a mechanism capable of storing energy. 4. The developing device according to claim 3, wherein said auxiliary means releases energy accumulated when the holding member is accelerated in rotation. 5. The energy storage device according to claim 3, wherein the auxiliary means stores energy when the rotation of the holding member is decelerated.
3. The developing device according to claim 1. 6. The apparatus according to claim 4, wherein the driving unit is driven at a low speed when the holding member stopped at a position other than a predetermined developing position is rotated to a predetermined developing position of the developing device. 3. The developing device according to claim 1. 7. The developing device according to claim 3, wherein the mechanism capable of storing the energy uses a cam and an elastic body. 8. The developing device according to claim 1, wherein said driving means is a stepping motor. 9. The developing device according to claim 1, wherein said driving means is a DC servomotor.