JPS61133964A - Developing device - Google Patents

Abstract

PURPOSE:To simplify construction and to permit the transfer of a desired color by providing plural developing devices around a photosensitive body and controlling the developing devices in such a manner that the roller of one developing device among the plural developing devices is selectively rotated. CONSTITUTION:The plural developing devices 3, 4 are provided around the photosensitive drum 1. An electrostatic latent image is formed on the drum 1 and the developer is stuck to the drum from the developing devices 3, 4 to develop the image. The developing devices 3, 4 are controlled in such a manner that the drum 4a of one device 4 thereof is selectively rotated to stick the developer to the drum 1. On the other hand, the drum 3a of the other device 3 is not rotated and the bias voltage is not impressed so that the developer is not stuck to the photosensitive drum. Only the drum of one developing device is rotated and controlled selectively while the plural developing devices are held always in proximity to the photosensitive drum and therefore the transfer of the desired color is made possible and the construction is made simple.

Description

Detailed Description of the Invention (Scope of Industrial Application) The present invention relates to a developing device having a plurality of developing units around one image bearing member such as a photoreceptor, and more specifically relates to a developing device having a plurality of developing units around an image bearing member such as a photoreceptor. Turn on the rotation of each developing roller in the developing device
, relates to a developing device configured to enable OFF control.

(Prior Art) In recent years, color copying machines have become increasingly popular, and developers in colors other than black, such as red, blue, green, and sepia, have appeared.

However, conventional copying machines have separate developing devices for each of these types of developers, and users have to replace these developing devices to make desired color copies. In such copying machines, the developing device must be replaced depending on the desired color, which is troublesome for the user, and there is a risk that the inside or outside of the machine may be contaminated with developer during replacement. .

In order to eliminate the above-mentioned drawbacks, copying machines that are equipped with a plurality of developing devices have recently been proposed. If a plurality of developing devices are built-in, the user can select a desired color on the operation panel without having to replace the developing device each time, which is very convenient. By doing this, the frequency of replacing the developing device was reduced, and the amount of contamination outside the machine was also reduced. However, conventionally proposed multicolor built-in copying apparatuses have the following sequence configuration. When one developing device is selected, the other developing devices are separated from the photoreceptor (more specifically, the developing sleeve is separated from the photoreceptor and cannot perform development), and then when the copying operation is completed, The developing devices that were in the developing state are separated from the photoreceptor, and as a result, all the developing devices are separated from the photoreceptor. Further, when another developing device is selected thereafter, the selected developing device is pressed against the photoreceptor and becomes ready for development at the start of the copying operation.

The conventional example will be described in more detail using FIGS. 3 and 4. Although a copying machine having two developing devices will be described here, the same thing can be said even if there are three or more developing devices.

In FIG. 3, the photosensitive drum 1 is rotating in the direction of the arrow in the figure. 2 is a charger located at the most upstream side and uniformly charges the surface of the photoreceptor; 5 is an exposure duct for isolating the document image light beam from the optical system from the surroundings; and 6 is a charger for removing electric charges from unnecessary parts outside the image area. 7 is a potential sensor for measuring the surface potential of the photosensitive drum; 3 is a first developing device; 4 is a second developing device; 8 is an eccentric roller for moving the first developing device; 9 is an eccentric roller for moving the second developing device; 10
11 is a charger for image transfer, 11 is a charger for separating the transfer paper, and 12 is a cleaner for removing residual toner after transfer. The transfer paper is fed out in synchronization with the developed image on the drum 1 by the registration roller 13, the image on the drum is transferred by the transfer charge N10, and then separated from the drum l by the separation charger 11 and fixed on the conveyor belt 14. and a container (not shown).

FIG. 3 shows a state where the first developing device is selected and the second developing device is selected.
If the developing device is selected, the developing device 4 is close to the drum 1, contrary to FIG. 1, and the developing device 3 is separated from the drum 1.

A color selection method for a conventional copying machine will be described using FIG. When the copying machine is not in operation, the developing units 3 and 4 are both shown as solid lines in the figure, and are spaced apart from the photosensitive drum 1. When either the developer selection button 52 or 53 is pressed on the operation panel in FIG. 6 to select a desired color, and the copy start button 51 is pressed, a developer corresponding to the selected color in the developing device 3 or 4 is is pressed against the drum. This can be achieved by bringing the eccentric roller 8 or 9 into the state shown by the dashed line in the figure using the driving force of a motor or the like (not shown). When the copying operation is completed, the eccentric roller 8 or 9 is again rotated in reverse by a motor or the like and moved to the position shown by the solid line, so that both developing units are separated from the drum 1.

Then, if the same color is specified again, the same operation as above can be repeated to obtain a copy. Conversely, if another color is specified, the opposite color will be selected.

Now, in conventional copying machines such as KM, pressure is turned on to the drum along with the developing device every time a copy is made.

The pressure mechanism itself must be reliable in order to repeatedly turn off.
This has the disadvantage that durability is required and as a result, expensive parts must be used.

In addition, since the pressure on the drum is repeatedly turned on and off, the vibrations and shocks generated during this process cause the developer inside the developing device to spill out and contaminate the inside of the machine.

Furthermore, due to such ON and OFF operations, developer is scattered from the higher-position developing device 3 (in FIG. 3, the first developing device 3 is located at a higher position than the second developing device 4 in the direction of gravity). There is a drawback in that the developer enters the lower developing device 4 and mixes the color with the developer in the developing device 4.

(Purpose) The uninvented invention was created in view of the drawbacks of conventional copying machines as mentioned above, and the first purpose is to provide a simple structure with fewer operating parts and high reliability and durability. The purpose of the present invention is to provide a multi-color built-in copying machine.

Another object of the present invention is to reduce the number of moving parts and reduce the vibrations and shocks applied to the developing device, thereby reducing the scattering of developer inside the machine.

(Example) The invention will be explained in detail based on examples.

Fig. 5 shows an embodiment of the present invention.6 The embodiment of the present invention shows a copying machine that has two built-in developing units, but is not necessarily limited to this, and may have three or more built-in developing units. I don't mind.

The reference numerals shown in FIG. 5 are the same as those shown in FIG. 3, and their functions are the same as those shown in the conventional example of FIG. 1, so they will not be described in detail here.

The difference between FIG. 5 and FIG. 3 is that both the developing units 3 and 4 are constantly pressurized against the drum 1. In this case, both sleeves 3a and 4a are rotatable while maintaining a constant gap with respect to the drum. In this case, the eccentric rollers 8 and 9 may be operated automatically or manually, but once the developing units 3 and 4 are set in the main body, the developing units are always kept in a pressurized state against the drum until they are taken out of the machine again.

Therefore, in the copyable state where copies can be made by pressing the copy button, the two developing units are always in a pressurized state S(
(ready for development).

In FIG. 5, for example, it is assumed that the upper developing device 3 of the two developing devices is selected. This can be achieved by pressing the developing unit selection button 52 in FIG. A bias voltage is applied to form a developed image on the drum 1 corresponding to the electrostatic latent image on the drum 1. At this time, the developing sleeve 4a in the developing device 4 does not rotate and remains stationary, and no bias voltage is applied to the sleeve, that is, the sleeve 4a is in an electrically floating state.

Therefore, the developed image on the drum developed by the developing device 3 reaches the transfer section without being affected by the developing device 4, and is transferred onto the transfer paper as described above.

On the other hand, if the developing unit selection button 53 is pressed and the lower position developing unit 4 is selected, the sleeve 4a starts to rotate with an appropriate bias voltage applied and the developer in the developing unit 4a is applied onto the drum 1. A developed image is created. At this time, developing device 3
The inner sleeve 3a has no bias voltage, is electrically floating, and is also stopped from rotating, so it does not affect the electrostatic latent image on the drum.

Developing sleeve 3a or 4 according to the present invention using FIG.
The rotation control of a will be explained. The output of the motor 21 is transmitted to a drum rotation input gear 23 via a chain or gear train 22, and rotates a drum gear 24 integrally formed with the drum 1 in a fixed direction. Meanwhile, the output of motor 21 is transmitted to gears 26 and 27 via another chain or gear train 25. Gear 26 meshes with gear 28, and gear 27 meshes with gear 29. The gear 28 is an armature member that constitutes the clutch 3Qa, and is idle when the clutch 30a is not energized. Therefore, the output of the motor 21 is sufficient to cause the gear 28 to idle. On the other hand clutch 3
When 0a is energized, the gear 28, which is a seven-way gear member, is integrally connected to the clutch shaft 30. As a result, gear 31
．． The rotational motion of the motor 21 is transmitted to the sleeve 3a via the sleeve 3a. Rollers 3b and 3c are disposed at both ends of the sleeve 3a so as to be freely rotatable completely independently of the sleeve 3a. Therefore, whether or not the sleeve 3& rotates, the roller 3b
, 3c rotate passively when the drum 1 rotates. The sleeve 3& always maintains a constant gap from the drum 1 without being affected by the rollers 3b, 3c.

The above-mentioned configuration is exactly the same for the sleeve 4a, and when the clutch 31 is energized, the rotational movement of the gear 29 is transmitted to the sleeve 4a via the clutch shaft 33 and gears 34 and 35. At both ends of the sleeve 4a, there are rollers 4b and 4c which are rotatably disposed completely independently of the sleeve 4a to ensure a gap between the sleeve 4a and the drum 1.

As explained in detail in FIG. 5, by applying an energizing signal only to the clutch 30a, the sleeve 3a can be rotated while the sleeve 4a is stopped. Conversely, if the energizing signal is applied only to the clutch 31, the sleeve 4a can be rotated while the sleeve 3a is stopped. By applying a necessary bias voltage to the sleeve in synchronization with the rotation of the sleeve, the latent image on the drum can be developed.

On the other hand, the bias voltage of the sleeve that does not contribute to the lump image is O
It has been FF.

FIG. 2 shows another embodiment for controlling the rotation of the developing sleeve of the present invention. In FIG. 1, the drum and the developing sleeve were driven by the same motor drive source, but in FIG. The power source and the drum drive source are separated and controlled by completely separate motors. Components having the same reference numerals as those in FIG. 1 have exactly the same functions. The output rotation of the motor 21 is controlled by a chain or a gear train 22. The drum 1 is rotated through gears 23 and 24. On the other hand, the rotation of the motor 36 is transmitted to the sleeve 3a via gears 31 and 32.

Therefore, by controlling the rotation of the motor 36 on and off, the rotation of the sleeve 3a can be controlled. Further, the rotation of the motor 37 is transmitted to the sleeve 4a via gears 34 and 35. The bias voltage required during development is applied to sleeve 3.
Needless to say, it is applied to a or 4a.

(Effects of the Invention) As described above, according to the present invention, the rotation control of the developing sleeve of a selected one (11 developing devices) of two or more developing devices is maintained close to the drum at all times. By carrying out this process, a transferred image of a desired color can be obtained.

Moreover, unlike the conventional example, there is no need to repeatedly move the developing sleeve toward and away from the drum for each copy, so there is no need for a complicated mechanism, and the present invention provides extremely reliable High 1. % copier can be obtained. Further, in the present invention, since the developing state and the non-developing state are created by controlling the rotation of the t± developing sleeve, it is possible to more reliably suppress the scattering of the developer inside the machine as in the conventional example.

In addition to the above-mentioned sleeve, the developing roller includes a magnet roller and the like. In addition to the photoreceptor, the image carrier includes members such as an insulating drum and a magnetic drum.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams showing the drive system of the developing device of the present invention, Figures 3, 4, and 5 are schematic diagrams showing the configuration of a two-color copying machine, and Figure 6 is a schematic diagram showing the operation buttons. The top view of the figure is shown. In the figure, 3.4 is a developing device, 21 is a motor, 30a,
31 is a clutch, and 36 and 37 are motors whose drive is controlled.

Claims (1)

[Claims] (1) an image carrier, a plurality of developing devices disposed around the carrier at regular intervals and each having a developing roller, and a selection means for selecting one of the plurality of developing devices; , a developing device having a rotation transmission control means for independently controlling the rotation of each of the developing rollers, the rotational movement is applied only to the developing roller of the developing device selected by the selection means via the rotation transmission control means. A developing device characterized by transmitting.