JPH03196072A - Developing device - Google Patents

Abstract

PURPOSE:To improve image quality without generating the excess and shortage of the supply rate of developers by scooping up the developers in developing containers, supplying the developers onto developer carrying members and varying the relative rotating speeds with the developer carrying members. CONSTITUTION:this device has the developer carrying members 50Y, 50M, 50C, 50B which are deposited with the developers on the peripheral surfaces, transport these developers, develop the electrostatic latent images of a latent image carrying member by the carried and transported developers, and are variable in speeds. Revolving developer agitating members 52Y, 53M, 52C, 52B which scoop up the developers in the developing containers 51Y, 51M, 51C, 51B while agitating the developers, supply the developers to the developer carrying members 50Y, 50M, 50C, 50B and can be varied in the relative rotating speeds with the developer carrying members 50Y, 50M, 50C, 50B are provided. Thus, the supply of the developers to the developer carrying members 50Y, 50M, 50C, 50B and the agitation of the developers are executed without the excess and shortage and the image quality is additionally improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a dry type developing device for visualizing an electrostatic latent image formed on a latent image carrier using a powder developer. It is something.

[Conventional technology]

2. Description of the Related Art In image forming apparatuses such as copying machines, facsimile machines, and printers, the above-mentioned type of developing device is widely used in so-called electronic copying type image forming apparatuses that form an electrostatic latent image on a latent image carrier.

In such a developing device, a developer is carried and conveyed on the circumferential surface of a developer carrying member such as a developing sleeve, and the electrostatic latent image on the latent image carrier is visualized with the carried and conveyed developer. For example, when a two-component developer containing a carrier and a toner is used as the developer, the developer is thoroughly mixed and stirred using a developer rotation stirring member such as a paddle wheel.

The toner is triboelectrically charged to a predetermined amount of charge while being supplied to the developer carrying member.

Incidentally, in recent years, image forming apparatuses such as copiers that can make not only monochrome copies but also color copies have become increasingly used in offices. It is also possible to change the developing conditions according to various copy modes by changing the rotation speed of the member. Even if there are changes in the electric field or the linear velocity of the latent image carrier, the control is performed so that the coby density and density gradation are almost the same.

Conventionally, the configuration has been such that the mutual rotational speed ratio of the developer carrying member and the developer rotating and stirring member cannot be changed.

[Problem to be solved by the invention]

With such a configuration, when the rotational speed of the developer carrying member is controlled to be reduced, for example, the rotational speed of the developer rotating and agitating member is reduced, resulting in insufficient agitation of the developer, or In addition, when the rotational speed of the developer carrying member is increased, the rotational speed of the developer rotating and agitating member also increases, resulting in the inconvenience that more developer is supplied than necessary. .

An object of the present invention is to make it possible to change the relative rotational speed of a developer rotating and agitating member with respect to a developer carrying member, thereby preventing excess or insufficient supply of developer or insufficient agitation, thereby improving image quality. An object of the present invention is to provide a developing device which is designed to improve the performance.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention includes a developing device according to the present invention, which carries a developer on its peripheral surface and conveys it, and uses the carried and conveyed developer to form an electrostatic latent image on a latent image carrier. A developer carrying member capable of changing the speed for developing images, pumping up the developer in the developing container while stirring and supplying the developer to the developer carrying member, and changing the speed so that the relative rotational speed with the developer carrying member can be changed. The invention is characterized in that it is constructed with a developer rotation agitation member that enables rotation of the developer.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a color copying machine equipped with a developing device according to an embodiment of the present invention, and in order to understand the present invention, the overall structure thereof will first be explained.

In this copying machine, first, an illuminating device 11 illuminates a document (not shown) placed on a contact glass 10.
Illumination scanning is performed by moving the mirror 12 to the right in the figure. The scanning light image at this time is the second mirror 13. which moves in the same direction. It enters the lens 15 via the third mirror 14, and then the fourth mirror 16. The image passes through the filter device 17 and is projected onto a drum-shaped photoreceptor 18, which is an example of a configuration of a latent image carrier. Filter device 1
7 has a plurality of color separation filters, and these filters can be rotated by 90'' so that they can be freely selected and used.

For example, a blue component light image is first taken out by one of these filters, and this light image is formed and projected onto the photoreceptor 18 which has already been uniformly charged by the charger 19. , thereby forming an electrostatic latent image on the photoreceptor.

Below the photoreceptor 18 is a yellow developing device 21Y.

A magenta developing device 21M and a cyan developing device 21C are provided, and the electrostatic latent image is first developed by the yellow developing device 21C.
A toner image is formed using 1Y yellow toner.

A transfer paper sent from a paper feed section 23 is wound around and held on the transfer drum 22, and the toner image is transferred by the transfer charger 20 onto the wrapped transfer paper.

Similarly, by using each of the other filters, the magenta toner image and cyan toner image formed on the photoreceptor are transferred to transfer paper and overlapped. When obtaining a black toner image, the electrostatic latent image is visualized by the black toner of the black developing device 21B. In addition, in the case of black exposure, use ND as a filter.
Filters may also be used.

50Y, 50M, 50G, and 50B in FIG. 1 are development sleeves that are examples of the structure of the developer carrying member,
These are provided in each developing device so as to face the photoreceptor 18, respectively. Each of the developing sleeves is driven to rotate in the direction of the arrow, carries developer on its circumferential surface, conveys the developer, and sequentially converts each electrostatic latent image on the photoreceptor 18 into a toner image.

After the toner image is transferred, the separation charger 24 and the separation claw 25
The transfer paper is separated from the transfer drum 22, and the separated transfer paper passes through the fixing device 26 and is discharged outside the machine as copy paper. On the other hand, toner remaining on the photoreceptor 18 after the toner image of each color is transferred is removed by a cleaning device 27 each time.

A two-component developer having a carrier and yellow toner is contained in the developer container 51Y of the yellow developing device 21Y, and is pumped up while being stirred by the rotation of a paddle wheel 52Y, which is an example of a developer rotating and stirring member. and supplied to the developing sleeve 50Y. Similarly for the other developing devices, developer containing toner of the corresponding color is pumped up while being stirred by each paddle wheel.

It is supplied to each developing sleeve.

By the way, the copying machine in this example allows you to select and execute copy modes such as monochrome copy mode, full color copy mode, single color copy mode, and various color erasing copy modes using color separation filters. The copying conditions are changed depending on the mode. Note that color-erased copy means to obtain copy paper in which specific colors in an image are erased.

For example, the linear speed of the photoreceptor during monochrome copying is set to 200 m.
/ sec, during color erasing copying, the output of the lamp (halogen lamp) of the illumination device 11 is assumed to be approximately 700 W, and since light in a limited wavelength range using a color separation filter is used, the photoreceptor is If the linear velocity is increased, the amount of light becomes insufficient, so the linear velocity is reduced to about 100 m/see.

Also, if the optimum rotation speed of the developing sleeve in normal monochrome copy mode is about 32 Or, p, a+ diameter,
When in color erase copy mode, the rotation speed is 16 Or, p.
, m. Conventionally, such speed change of the developing sleeve has been performed by a speed change drive motor 28' as shown in FIG. That is, the developing sleeve 50Y (the other developing sleeves are the same) and the paddle wheel 52Y (the other paddle wheels are the same).

The pinion 29' of the motor 28' and gears 30', 3 that mesh with the pinion 29' via an intermediate gear (not shown) as necessary.
1', but with such a driving means it was not possible to change the relative rotational speed ratio between the two.

That is, as shown by the broken line L1 in FIG. 4, when the rotational speed of the developing sleeve is changed, the rotational speed of the paddle wheel changes at the same ratio, changing the relative rotational speed of the paddle wheel with respect to the developing sleeve. This is because I can't do it.

With such a configuration, for example, when the rotational speed of the developing sleeve is reduced, the rotational speed of the paddle wheel also decreases with the same speed ratio, resulting in insufficient supply of developer to the developing sleeve.

The agitation properties of the developer may deteriorate. Further, when the rotational speed of the developing sleeve is increased, the paddle wheel is also raised, resulting in more developer being supplied to the developing sleeve than necessary.

Therefore, in one example, a variable-speed paddle wheel is used as the paddle wheel so that the relative rotational speed with respect to the developing sleeve can be changed.

For example, as shown in FIG. 2, the developing sleeve 50Y (the other developing sleeves are the same) and the paddle wheel 52Y (the other paddle wheels are the same) are connected to the variable speed drive motor 28, its motor pinion 29, and the like as necessary. Depending on the intermediate gear (
They are rotated by gears 30, 31, etc. that mesh with them via gears (not shown). A known transmission mechanism 32 is provided between the gear 31 and the paddle wheel 52Y,
By controlling this speed change mechanism 32, the paddle wheel 52Y can change speed. Similarly, each paddle wheel of the other developing devices 21M, 21C, and 21B can be changed in speed.

Note that this paddle wheel may be driven by a separate variable speed drive motor to provide a drive configuration independent of the developing sleeve.

In FIG. 4, line L3 is an example of an optimum rotation ratio characteristic curve between the paddle wheel and the developing sleeve. The optimum characteristic curve referred to here is a characteristic curve in which the paddle wheel stirs the developer just enough and the developer is supplied to the developing sleeve just enough.

For example, when monochrome copying is performed, when the number of revolutions of the developing sleeve is 32 Qr, p, m, the number of revolutions of the paddle wheel is about 315 r, p, m. Also, in the color erase copy mode, the number of revolutions of the developing sleeve is set to 16.
When Or, p, and m, the number of rotations of the paddle wheel is 2.
15r, 1. Let it be m. In this way, the relative rotational speed of the paddle wheel with respect to the developing sleeve is changed, and the speed ratio thereof is changed.

By doing this, the rotational speed of the paddle wheel can be set to the optimum speed, and in any copy mode, the developer can be sufficiently agitated, and the developer can be kept in the developing sleeve. It is possible to supply just the right amount. After all, images of good quality can be obtained in any mode. Additionally, since the paddle wheel does not have to rotate at an unnecessarily high speed, stress on the developer can be kept to a minimum.

It is possible to suppress deterioration of the developer.

Note that by preventing the developer from being carried on the developing sleeve during non-development, for example, in the case of an image forming apparatus having only a black developing device, it is possible to prevent unnecessary black toner from adhering to the photoreceptor during non-development. It is possible to prevent skin stains, etc. Further, in the case of a color image forming apparatus, by preventing developer from being carried on the developing sleeve of a developing device that is not performing development, it is possible to prevent color mixing between the developing devices.

If the paddle wheel is rotated at high speed during such non-developing time, the developer will fly up in the developer container and scatter toward the photoreceptor, causing background stains.
In particular, if toner is to be replenished during non-development, the paddle wheel must be rotated to stir the developer, and if this is done, the developer will scatter. During non-development, if the paddle wheel is rotated at a low speed, for example 100r, p, m, the developer will be less likely to fly up and the developer will be prevented from scattering around the photoreceptor. Become. In this example, such a thing can also be done.

The present invention is applicable not only to an image forming apparatus having a plurality of developing devices but also to an image forming device having one developing device.

〔Effect of the invention〕

According to the configuration of the present invention, it is possible to change the relative rotational speed of the developer rotation stirring member with respect to the developer carrying member.
It is possible to supply the developer to the developer carrying member and to agitate the developer in just the right amount, thereby further improving the image quality.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a color copying machine equipped with a developing device according to an embodiment of the present invention, and FIG. 2 is a diagram of a drive system for a developing sleeve and a paddle wheel of the same developing device. FIG. 3 is a diagram showing the drive system for the developing sleeve and paddle wheel of a conventional developing device, and FIG. 4 is a diagram showing characteristics regarding the relative rotational speed ratio between the developing sleeve and paddle wheel in the conventional example and the present invention. be. 21Y, 21M, 21C, 21B...Developing device 50Y
, 50M, 50G, 50B...Developing sleeves 51Y, 51M, 51G, 51B...Developing container 52Y as developer carrying members
, 52M, 52C, 52B... Paddle wheel as a developer rotation stirring member

Claims (1)

[Claims] A variable-speed developer carrying member that carries and conveys developer on its peripheral surface and visualizes an electrostatic latent image on a latent image carrier with the carried and conveyed developer; The developing device is provided with a developer rotation stirring member whose speed is variable so that the developer is pumped up while stirring and supplied to the developer carrying member, and the relative rotational speed with the developer carrying member can be changed.