JP2001066880A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent image quality by making the amount and the electrification of toner on a developing roller uniform without prolonging the idling time in the case of initialization. SOLUTION: A supply roller 23 is rotated more quickly at the idling operation time in the case of initialization than at the ordinary printing operation time. The idling operation is also performed before starting printing just after restoring from a standby mode and the roller 23 is rotated more quickly than at the ordinary printing operation time. The revolving speed of the roller 23 is made different between at the idling operation time just after restoring from the standby mode and at the idling operation time in the case of initialization, and the revolving speed thereof at the idling operation time in the case of initialization is set to twice as high as at the ordinary printing time, and that at the idling operation time just after restoring from the standby mode is set to 1.5 times as high as at the ordinary printing operation time. Rotating speed is changed by using the same motor between a developing roller 24 and the roller 23 and switching a gear, or using an independent motor and controlling the speed of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, and more particularly to an electrophotographic apparatus using a developing device having a supply roller for supplying toner to a developing roller.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus used for a printer, a copying machine, a facsimile or the like, a light beam is scanned by an exposure unit on a photoreceptor whose surface is charged by a photoreceptor charger. An electrostatic latent image is formed, the latent image is developed with toner by a developing device, and the toner image is transferred and fixed on a printing paper to obtain an image.

[0003] Toner development is performed by a developing roller of a developing device, and a supply roller is used to stably supply toner to the developing roller. In a conventional electrophotographic apparatus, the rotation speed of the supply roller is constant, irrespective of the normal printing state and at the time of initialization, and is linked with a gear to maintain a certain speed difference from the developing roller.

[0004] The function of the supply roller is to supply toner to the developing roller and to scrape off the toner, and to replace the toner on the developing roller. When the printing is completed and the apparatus is stopped, the air between the toner particles is released and the toner on the developing roller is in a dense state. This phenomenon is called soft blocking. Further, the toner floating around the developing roller accumulates, and as a result, the amount of toner increases. Further, in the long-term stop state, the toner on the developing roller is constantly exposed to the environment, and toner deterioration occurs. When printing is resumed in this state, the image density suddenly rises, or fog increases due to insufficient charging of the toner, resulting in deterioration of image quality.

Conventionally, such a problem has been dealt with by driving the developing roller and the supply roller at the same speed as at the time of printing at the time of initialization before printing (rotating operation).

[0006]

In the above-described conventional electrophotographic apparatus, the amount of toner on the developing roller and the uniformity of charging are often insufficient because the time required for the turning operation is not sufficient.

Further, if the time for the turning operation is lengthened to prevent this, there is a problem that the operability and workability are deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic apparatus which can obtain a good image quality by uniformizing the amount and charging of the toner on the developing roller without lengthening the time required for the initial rotation.

[0009]

According to the present invention, there is provided an electrophotographic apparatus having a developing roller and a supply roller for supplying toner to the developing roller. It is characterized in that it is rotated faster than at the time of the printing operation.

The electrophotographic apparatus according to the present invention performs a spinning operation immediately before the start of printing immediately after returning from the standby mode, and rotates the supply roller at the time of the spinning operation immediately after the return from the standby mode as compared with a normal printing operation. It may be characterized.

The electrophotographic apparatus according to the present invention may be characterized in that the number of rotations of the supply roller is different between a rotating operation immediately after returning from the standby mode and a rotating operation at the time of initialization.

An electrophotographic apparatus according to the present invention is an electrophotographic apparatus having a developing roller and a supply roller for supplying toner to the developing roller. It may be characterized in that the roller is rotated more quickly during a rotating operation immediately after returning from the standby mode than during a normal printing operation.

[0013] The electrophotographic apparatus of the present invention may be characterized in that the supply roller is rotated at twice the speed of a normal printing operation at the time of a rotating operation at the time of initialization.

The electrophotographic apparatus according to the present invention may be characterized in that the supply roller is rotated at a speed 1.5 times faster than during a normal printing operation at the time of a turning operation immediately after returning from the standby mode.

The electrophotographic apparatus according to the present invention may be characterized in that the supply roller is driven by the same motor as that for driving the developing roller, and the rotation speed of the supply roller is changed by switching gears.

The electrophotographic apparatus according to the present invention may be characterized in that the supply roller is driven by a different motor from that for driving the developing roller, and the rotation speed of the supply roller is changed by controlling the speed of the motor.

The electrophotographic apparatus of the present invention may be characterized in that the developing system is a non-magnetic one-component developing system.

[0018]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of the electrophotographic apparatus of the present invention. The electrophotographic apparatus is used for a printer, a copying machine, a facsimile, and the like. FIG. 1 shows an example in which the apparatus is used for a printer.

An electrophotographic apparatus which receives a print signal from a host device, develops an electrostatic latent image formed on the photosensitive drum 1, and transfers the developed image to a print sheet 2. The photosensitive drum 1 and the photosensitive drum 1, an exposure unit 4 for forming an electrostatic latent image on the photosensitive drum 1, and an electrostatic latent image formed on the photosensitive drum 1 to be visualized and developed using toner. Developing device 5, a transfer device 6 for transferring the toner image formed on the photosensitive drum 1 formed by the developing device 5 to the printing paper 2, and a toner remaining on the photosensitive drum 1 without being transferred to the printing paper 2. And a photoreceptor cleaner 7 for cleaning.

The printing paper 2 is fed from the paper feeding unit 8 into the apparatus, and the toner image transferred from the photosensitive drum 1 is fixed to the fixing unit 9.
And discharged by the discharge unit 10 to the outside of the apparatus. The control unit 11 controls these units.

Of these units, the photosensitive drum 1
A unit called an EP (electrophotography) cartridge in which the photoconductor charger 3, the developing device 5, and the photoconductor cleaner 7 are integrated is used. This method aims at miniaturization of the device or easy replacement of consumables.

FIG. 2 is a configuration diagram of the EP cartridge according to the first embodiment of the present invention. As described above, the EP cartridge includes the photosensitive drum 1, the photosensitive charger 3, and the developing device 5.
And a photoreceptor cleaner 7. The developing device 5 includes a stirring mixer 21, a toner hopper 22, a supply roller 23, a developing roller 24, a toner blade 25, and a developing chamber 26. A non-magnetic one-component toner is used as a developer. The stirring mixer 21 stirs the toner in the toner hopper 22. The supply roller 23 is used for stably supplying toner to the developing roller 24 as described above. In addition, there is also an effect of supplying toner to the developing roller 24 and scraping off the toner, and has a function of replacing the toner on the developing roller 24. The toner blade 25 is a developing roller 2
Control of the thickness of the toner layer on the four surfaces and charging of the toner are performed.

The supply roller 23 and the developing roller 24 are driven by a drive motor (not shown). The transmission of the driving force from the driving motor and the change in the number of revolutions of the supply roller 23 are performed by gears. This control is performed by the control circuit of the control unit (11 in FIG. 1). FIG. 3 is a plan view of the drive transmission mechanism. FIG. 4 is a side view of the drive transmission mechanism.

Next, the operation will be described with reference to FIGS. 2, 3 and 4. At the time of normal printing, when the developing roller 24 is rotated by the drive motor in the EP cartridge of FIG. 2, the supply roller 23 connected by a gear also rotates. The number of rotations of each member is determined by the gear ratio of the gears. As shown in FIG. 4A, the rotation from the drive motor 31 drives the developing roller gear 36 and the supply roller gear 37 through the gear 32.

In the rotating operation at the time of initialization, the mechanism for changing the rotation speed of the supply roller 23 receives an initialization signal from the control circuit, and changes the number of teeth of the supply roller 23 to increase the rotation speed. Then, a speed difference with the developing roller 24 different from that during normal printing is generated.

That is, as shown in FIG.
The gear 33 slides on the same axis as the gear 32 and the gear 3
4 and the gear 32 and the supply roller gear 37
Disengagement. The gear 33 meshes with a supply roller gear 37 through a gear 34 and a gear 35. (Gear 32
The mechanism for sliding is not shown. At this time, the ratio of the number of rotations of the developing roller 24 and the supply roller 23 is 1: 1 during normal printing, and 1: 2 during the initial rotating operation.
Set the number of teeth for each gear so that As a result, the number of rotations of the supply roller 23 during the initial rotation operation is twice as large as during normal printing.

Next, a second embodiment of the present invention will be described. FIG. 5 is a plan view of the drive transmission mechanism according to the second embodiment. The second embodiment differs from the first embodiment in that the supply roller 23 is rotated by an independent drive motor 38 as a speed changing mechanism.

Next, a third embodiment of the present invention will be described. In the third embodiment, not only the initial rotation operation at the time of initialization but also the initial rotation operation before returning to the standby mode (power saving mode) and before the start of the printing operation, the supply roller 23 is rotated during the normal printing operation. It has a mechanism to rotate faster and a control circuit for that.

Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, the supply roller 23
And a control circuit for setting the number of revolutions to be different between the rotating operation at the time of initialization and the rotating operation immediately after returning from the standby mode (power saving mode). Each drive motor is set so that the ratio of the number of rotations of the developing roller 24 and the supply roller 23 is 1: 1 during normal printing, 1: 2 during initialization, and 1: 1.5 when returning from the standby mode. Control. As a result, the number of rotations of the supply roller 23 is set to 2 during normal printing during the initial rotation operation.
When returning from the standby mode, it becomes 1.5 times that in normal printing. The reason why the rotation speed at the time of returning from the standby mode is smaller than that at the time of initialization is that the printing pause in the standby mode is shorter than the printing pause time until the initialization, and the rotating operation when returning from the standby mode. Is performed many times during the day to prevent the toner from being damaged.

[0030]

As described above, according to the present invention, the supply roller is rotated faster at the time of the rotating operation at the time of initialization or at the time of the rotating operation immediately after returning from the standby mode than at the time of the normal printing operation. This has the effect of stabilizing the toner amount and stabilizing the image density.

Further, there is an effect that the charging of the toner on the developing roller is stabilized and the fog of the image is reduced.

Further, there is an effect that the soft blocking of the toner due to long-term storage (pause of printing) is prevented and the image quality is stabilized.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electrophotographic apparatus of the present invention.

FIG. 2 is a configuration diagram of an EP cartridge according to the first embodiment.

FIG. 3 is a plan view of the drive transmission mechanism according to the first embodiment.

FIG. 4 is a side view of the drive transmission mechanism according to the first embodiment.

FIG. 5 is a plan view of a drive transmission mechanism according to a second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 2 printing paper 3 photoconductor charger 4 exposure unit 5 developing device 6 transfer device 7 photoconductor cleaner 8 paper feeding unit 9 fixing unit 10 discharging unit 11 control unit 21 stirring mixer 22 toner hopper 23 supply roller 24 developing roller 25 Toner blade 26 Developing chamber 31 Drive motor 32 Gear 33 Gear 34 Gear 35 Gear 36 Developing roller gear 37 Supply roller gear 38 Drive motor

Claims (9)

[Claims] 1. An electrophotographic apparatus having a developing roller and a supply roller for supplying toner to the developing roller, wherein the supply roller is rotated faster during a rotating operation at the time of initialization than during a normal printing operation. Electrophotographic equipment. 2. A spinning operation is performed before printing immediately after returning from the standby mode, and the supply roller is rotated faster than a normal printing operation during the spinning operation immediately after returning from the standby mode. Item 1. An electrophotographic apparatus according to Item 1. 3. The supply roller according to claim 2, wherein the number of rotations of said supply roller is different between a rotation operation immediately after returning from a standby mode and a rotation operation during initialization.
An electrophotographic apparatus according to the above. 4. An electrophotographic apparatus having a developing roller and a supply roller for supplying toner to the developing roller, performs a rotating operation before starting printing immediately after returning from a standby mode, and returns the supply roller from the standby mode. An electrophotographic apparatus characterized in that it rotates faster during a direct rotation operation than during a normal printing operation. 5. The electrophotographic apparatus according to claim 1, wherein the supply roller is rotated at twice the speed of a normal printing operation at the time of a rotating operation at the time of initialization. 6. The printing apparatus according to claim 2, wherein the supply roller is rotated at a speed 1.5 times that of a normal printing operation at the time of a turning operation immediately after returning from the standby mode.
Or the electrophotographic apparatus according to 5. 7. The supply roller is driven by the same motor as that for driving the developing roller, and the rotation speed of the supply roller is changed by switching gears. 7. The electrophotographic apparatus according to 5 or 6. 8. The apparatus according to claim 1, wherein the supply roller is driven by a different motor from that for driving the developing roller, and the rotation speed of the supply roller is changed by controlling the speed of the motor. 7. The electrophotographic apparatus according to 5 or 6. 9. The electrophotographic apparatus according to claim 1, wherein the developing system is a non-magnetic one-component developing system.