JPH01105972A - Developing device - Google Patents

Abstract

PURPOSE:To strengthen the torque at low speed, to prevent the fluctuation of a load of a developing device and to improve the picture quality by using an ultrasonic motor for a driving source for a developer carrying member of the developing device. CONSTITUTION:To one end side of a developing sleeve 3 for carrying developer of a developing device 1, a rotor 12 of an ultrasonic motor 10 is fixed with a screw 13 through an elastic member 11. Also, a ring-like stator 16 for the ultrasonic motor sticking a piezoelectric body made of piezoelectric ceramic to an elastic member 14 by a copper alloy, etc., is stuck to a frame 2a of a developing device body 2. Subsequently, the contact pressure of the mutual opposed surfaces of said rotor 12 and stator 16 is adjusted to a suitable value by tightening a screw 17 screwed to a shaft part 3a of the sleeve 3, a driving power source is supplied to the stator 16 by a feeding means, and the sleeve 3 formed integrally with the rotor 12 is driven directly. In such a way, the ultrasonic motor whose torque is large at low speed is used, the load fluctuation of the developing device 1 is prevented, the picture quality is improved and the device is miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention J (Industrial Field of Application) The present invention is applicable to image forming apparatuses such as electronic copying machines and laser printers, and is applicable to electrostatic charges formed on an image carrier. The present invention relates to a developing device that develops a latent image.

(Prior Art) Conventionally, one of the developing devices of this type is shown in FIGS. 3 and 4.
A non-contact one-component developing device as shown in the figure has been put into practical use.

As shown in FIG. 3, this developing device a has a structure in which a developing sleeve C1 supplying roller d as a developer conveying member, an agitator e, a coating blade f, etc. are arranged inside the developing device main body. At the same time, a one-component developer (hereinafter referred to as toner) g is accommodated.

As the developing sleeve C rotates, the toner g passes between the developing sleeve C and the coating blade f that is in pressure contact with the developing sleeve C, and a uniform toner layer g' is formed on the developing sleeve C.
is formed, and this toner layer g' is conveyed to a developing area of a photosensitive drum i as an image carrier.

On the other hand, between the photoreceptor drum i and the developing sleeve C, a pair of guide rollers j, j (see FIG. 4) provided coaxially with the developing sleeve C are brought into contact with the photoreceptor drum i, thereby allowing a predetermined A gap G is now formed.

Then, by applying an appropriate bias voltage to the developing sleeve C from the bias power supply k, the developing sleeve C
The toner g in the toner layer g' formed thereon is caused to fly, and the electrostatic latent image on the photosensitive drum 1 is visualized.

Further, at one end of the developing device a, as shown in FIG. 4, a driven gear n is provided coaxially with the developing sleeve C and guide rollers j, j. This driven gear n is driven by a drive source (DC motor) I! in the main body of the image forming apparatus. The driving force of is meshed with gear m, which is transmitted through a power transmission system with a reduction function (not shown) consisting of a group of gears and a coupling.
As the driven gear n rotates, the developing sleeve C, guide rollers j, j, and the supply roller d and the agitator e, which are interlocked via the gear group O, are driven.

(Problems to be Solved by the Invention) As described above, the conventional developing device a converts the driving force of the rotating bodies such as the developing sleeve C and the guide rollers j and j into gears and couplings with a speed reduction function. It is configured to receive power from the outside via a power transmission system.

For this reason, play in the gears and couplings that make up the power transmission system, and the synchronization of one rotation of the developing sleeve C, causes uneven rotation and load fluctuations in the developing sleeve C and guide rollers j, and The thickness of the toner layer g' becomes non-uniform and the rotation accuracy of the photosensitive drum 1 decreases, which seriously affects the image quality. Further, since a power transmission system is required, there is a problem in that it becomes an obstacle to downsizing an apparatus in which the developing device is incorporated.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide a developing device that is capable of high-quality image development and that also enables miniaturization of the device into which it is incorporated. .

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes a developing device main body, and a developing device that is housed in the developing device main body and conveys developer to a developing area as it rotates. The developing device includes a developer transporting member for developing an electrostatic latent image on an image carrier, and an ultrasonic motor is used as a drive source for the developer transporting member.

(Function) In other words, the present invention is configured to use an ultrasonic motor with low speed and high torque, thereby making it possible to prevent load fluctuations in the developing device, improve image quality, and eliminate the need for a large proprietary It is possible to eliminate a power transmission system with a reduction function that requires space, and it is possible to downsize the device to be incorporated.

(Example) Hereinafter, one example of the present invention will be described with reference to FIGS. 1-2.

FIG. 2 is a partially cutaway external perspective view of the developing device 1. In the developing device main body 2 of the developing device 1, there is a developing sleeve 3 as a developer conveying member, as in the above-mentioned conventional example.
．． Supply roller (not shown), stirring body (not shown),
It has a configuration in which a coating blade 4 and the like are disposed, and a one-component developer (toner) (not shown) is accommodated therein.

Further, the developing sleeve 3 is supported in the radial direction by having shaft portions 3a, 3a formed at both ends thereof attached to the frames 2a, 2a of the developing device main body 2 and passing through bearings 6.6. The shaft portions 3a, 3a
Guide rollers 8, 8 as contact members are attached via bearings 7.7 to the photosensitive drum 5 and the developing sleeve 3 in contact with the photosensitive drum 5 as an image carrier.
A predetermined gap G (see FIG. 1) is formed between the two.

Further, an ultrasonic motor 10 is provided at one end of the developing sleeve 3 as a drive source for driving the developing sleeve 3, the supply roller, and the stirring body.

That is, as shown in FIG. 1, a ring-shaped ultrasonic motor rotor 12 made of aluminum alloy or the like is attached to one end surface of the developing sleeve 3 through a screw 13 and an elastic member 11 having a damper function. It is fixed via... Also,
A ring-shaped stator 16 for an ultrasonic motor is connected to the frame 2a of the developing device main body 2. The stator 16 is a ring-shaped stator 16 for an ultrasonic motor, which has a piezoelectric body 15 made of a piezoelectric ceramic such as PZT bonded to an elastic member 14 made of a copper alloy or the like. There is.

The ultrasonic motor rotor 12 and the ultrasonic motor stator 16 have a diameter that is the same as or smaller than the diameter of the developing sleeve 3.

Further, the contact pressure between the rotor 12 and the stator 16 on mutually opposing surfaces is adjusted to an appropriate value by tightening a screw 17 screwed into the shaft portion 3a of the developing sleeve 3, and the contact pressure on the stator 16 is is adapted to be supplied with driving power through a power supply means (not shown), and to directly drive the developing sleeve 3 integrated with the rotor 12.

Further, a gear 18 is externally fitted between the frame 2a of the shaft portion 3a and the guide roller 8, and is prevented from rotating by a pin 19.
The driving force of the gear 18 is transmitted via an intermediate gear 19 to a gear 20 integrated with the supply roller and a gear 2 integrated with the agitator.
1.

In FIG. 2, 25 is a side seal, 26 is a collection blade, and 27 is a supply roller.

Thus, the developing sleeve 3 in the developing device 1 is operated by the ultrasonic motor 10 using the ring-shaped rotor 12 and the stator 16.
Since it is directly driven, low speed and high torque can be achieved, and a drive with good rotational stability can be configured even with load fluctuations within the developing device 1. Therefore, it is possible to maintain a uniform toner layer on the developing sleeve 3, and it is also possible to prevent a decrease in the rotation accuracy of the photosensitive drum 5 due to load fluctuations, that is, a deterioration in image quality.

In addition, since the developing device has a relatively large torque, it conventionally required a large motor to obtain torque by decelerating the device significantly, requiring a very large space. Since it does not have a drive mechanism for the developing device 1 using gears, couplings, etc., it does not require a large space and the main body can be made smaller, and the degree of freedom in design is also increased.

For example, in this embodiment, when the rotational speed of the developing sleeve 3 is 85 rpm and the required torque is about 4K9·a, conventionally, the DC motor is rotated at over 1,000 rotations and decelerated by gears etc. to generate the torque. However, in the ultrasonic motor 10, the rotation speed is 85 rpm and the required torque is 4 K'il.
α is obtained.

Further, since the ultrasonic motor 10 uses a ring-shaped rotor 12 and stator 16 that are the same or smaller in diameter than the developing sleeve 3, it can be easily miniaturized. sleeve 3
and is separately fixed to the frame 2a of the developing device main body 2, and after the developing sleeve 3 is assembled into the developing device 1,
Since it is a pressurized type, assembly efficiency is greatly improved.

Further, the developing sleeve 3 is rotated by the rotor 12, and generates rotational force by minute vibrations called ultrasonic waves, so when the vibration is transmitted onto the developing sleeve 3, the coating blade 4 forms a thin layer of toner in the developing device. In this case, the vibration of the coating blade 4 causes density unevenness in the toner layer on the developing sleeve 3, resulting in a defective image with density unevenness in the final image. In the example, since the rotor 12 is fixed to the developing sleeve 3 via the elastic member 11 having a damper function, a high quality image can be obtained.

Furthermore, since a bias is applied to the developing sleeve 3 when visualizing the electrostatic latent image, if a bias is also applied to the rotor 12, conduction will occur to the stator 16 that is in pressure contact, which will adversely affect the motor itself. The elastic member 14 is made of insulating material.

As described above, since it is possible to achieve miniaturization, it is very beneficial especially when applied to an image forming apparatus that requires a plurality of developing devices.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without changing the gist.

[Effects of the Invention] As explained above, according to the present invention, by using an ultrasonic motor with low speed and high torque,
It is possible to prevent load fluctuations on the developing device, improving image quality, and eliminating the need for a power transmission system with a speed reduction function, which requires a large dedicated space, allowing for the miniaturization of the device to be incorporated. This has the advantage that it is possible to provide a device that provides the following.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention,
Fig. 1 is a partial sectional view of the main parts, Fig. 2 is a partially cutaway perspective view of the developing device, Fig. 3 is an explanatory diagram of the operation of the non-contact one-component developing device, and Fig. 4 is a conventional one-component developing device. FIG. 3 is a perspective view of a developing device. 1...Developing device, 2...Developing device main body, 2a...
Frame, 3...Developing sleeve (developer transport member),
5... Photosensitive drum (image carrier), 10... Ultrasonic motor, 11... Elastic member, 12... Rotor, 14
... elastic member, 15 ... piezoelectric body, 16 ... stator. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (7)

[Claims] (1) Comprised of a developing device body and a developer conveying member housed within the developing device body and configured to convey developer to a developing area as it rotates to develop an electrostatic latent image on an image carrier. A developing device, wherein the developer conveying member is driven by an ultrasonic motor. (2) The developing device according to claim 1, wherein the ultrasonic motor is included within the developing device main body. (3) The developing device according to claim 2, wherein the ultrasonic motor is a ring type having the same or smaller diameter than the developer conveying member and directly drives the developer conveying member. (4) The ultrasonic motor is characterized in that the rotor side is fixed to the developer conveying member via an elastic member having a damper function, and the stator side is fixed to the frame of the main body of the developing device. Developing device according to item 3. (5) The developing device according to claim 4, wherein the elastic member is an insulating material. (6) Claims characterized in that the developing device main body includes a contact member for adjusting the gap with the image carrier, and develops in a non-contact state using a one-component developer. Developing device according to item 1. (7) The developing device according to claim 6, wherein the contact member is integrally attached to the developer conveying member.