JPS63298368A - Image forming device - Google Patents

Abstract

PURPOSE:To remarkably simplify a bias power unit and to reduce a cost by supplying DC bias voltages applied to developer carriers in plural developing devices from one power unit. CONSTITUTION:DC bias voltages applied to respective developing sleeves 111A and 111B of developing devices 11A and 11B are supplied from one bias power unit by a wiring circuit. That is, the plug of a connector to be connected to the bias power unit provided separatedly from developing devices 11A and 11B is attached to the side face of the vessel of the developing device 11A placed at the upstream of the rotation direction, and a receptacle on the bias power unit side is attached or detached to electrically connect or disconnect the bias power unit to the developing device 11A. Thus, DC bias voltages can be applied to all developer carriers by one bias power unit, and the number of power units is reduced and the wiring route is simplified to reduce the cost.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an image processing system in which two or more sets of developing devices for visualizing an electrostatic latent image formed on an image carrier are provided at the peripheral portion of the image carrier. The present invention relates to a forming device.

[Background of the invention]

Conventionally, as a developing device using a one-component developer containing a magnetic material or a two-component developer using a mixture of toner and a carrier that is a magnetic material, there is a magnetic brush developing device as shown in FIG. 4, for example. is used. 31 in the figure
is an image carrier that rotates in the direction of the arrow, and is made of, for example, ZnO, Se.
32 is a developing sleeve made of a non-magnetic cylindrical body which rotates in the direction of the arrow to convey the developer 'De to the developing area E.

Reference numeral 33 denotes a magnetic roll in which a plurality of magnets of different polarities are arranged radially in an alternating manner, and its magnetic force causes the developer De to adhere to the developing sleeve 32 and forms spikes. Reference numeral 34 denotes a spike regulating member provided on the upstream side of the development area E, which regulates the thickness of the developer layer so that the electrostatic latent image is developed under the best condition. Reference numeral 35 denotes a bias power supply applied to the developing sleeve 32, such as a DC bias for preventing toner scattering, developer capillary, etc., and 35m denotes a protective resistor.

This magnetic brush development! In Ifl, there are two methods: one method is to fix the magnetic roll 33 and rotate the developing sleeve 32 to perform the development, and the other is to perform the development by rotating the magnetic roll 33 as well.

However, the magnetic flux density and magnetic field distribution of the magnetic pole required for developer transport and the magnetic flux density and magnetic field distribution of the magnetic pole required for good development in the development area are generally different, and the magnetic roll rotating type is different from the fixed type. Compared to the conventional method, there are disadvantages such as a complicated drive mechanism, etc. Therefore, from this point of view, a magnetic roll fixing method in which magnets with different magnetic forces are arranged is advantageous.

Regarding the rotation direction of the developing sleeve 32, there are two methods in which development is performed while the rotating image carrier surface and the rotating developing sleeve surface rotate in the same direction (forward direction) in the developing area E, and a method in which development is performed while rotating in the opposite direction. There is a method to do this. However, developing by rotating in the opposite direction tends to cause a decrease in density at the leading edge of the image (first of all, the leading edge of the solid area), and it is difficult to transport the developer stably in the development area E (a layer of developer is likely to come out). ), development is often performed by forward rotation.

In any of the above methods, the developer layer regulated by the spike control member 34 forms a developer flow, is conveyed on the developing sleeve, and is conveyed to the development area E, where development is performed. The developer flow that has completed the development is conveyed to the developer reservoir in a form that adheres to the developing sleeve 32, but the developer that has completed the development remains attached to the developing sleeve 32 and is transferred to the developing area E in an overlapping manner. In order to prevent the developer from being conveyed, a scraper 36 is provided which slides into contact with the developing sleeve 32 and acts to strip off the developer.

In a general image forming apparatus, only one such developing device is provided at the periphery of the image carrier, but in an image forming apparatus that performs multi-color developing processing such as a twin-color copying device, each developing device is A plurality of developing devices containing developer are arranged in the rotational direction of the image carrier with respect to the circumferential surface of the image carrier in accordance with the processing order or vice versa.

[Problem that the invention seeks to solve]

Therefore, in such an image forming apparatus, a bias power supply must be prepared for each developing device and wired individually to form a complex bias power supply device, which requires a lot of equipment and work time. This was also a factor in raising the price of image forming apparatuses.

The object of the present invention is to solve this problem and provide an image forming apparatus in which the bias power supply device is extremely simple as a result of improvements, thereby realizing low cost.

[Means for solving problems]

The above object is to supply, in an image forming apparatus in which at least two developing devices are provided facing an image carrier, a DC bias voltage to be applied to the developer carrier in the plurality of developing devices from one power supply device. This is achieved by an image forming apparatus characterized by the following.

〔Example〕

An embodiment of the invention is shown in FIGS. 1-3.

FIG. 1 shows two image forming apparatuses showing one embodiment of the present invention.
This figure shows an outline of the configuration of a color copying machine. On the top of the copying machine body, there is a document table (Lath 1), and on the front edge of the top there is a display, a numeric keypad, and a color specification (developing device selection).
An operation panel (not shown) is provided on which buttons, an exposure setting volume, a paper size selection button, a copy start button, etc. are arranged.

When a document tray is set on the surface of the document platen glass 1 and the copy start button is operated, the exposure light source 3 scans the document tray for exposure, and the light image of the document tray includes the imaging lens 4a. The light is guided through the exposure device 4 to the surface of the photosensitive drum 2, which serves as an image carrier, that is, an image-bearing photoreceptor.

The photosensitive drum 2 has selenium or O on the outer circumferential surface of a grounded metal cylinder.
It is provided with a photoconductive layer such as PC, and rotates in the direction of the arrow (clockwise) in conjunction with the exposure scanning described above.

At the periphery of the photosensitive drum 2, a charging electrode 5, an exposure device 4, a two-color developer RA10 (to be described later), a transfer electrode 6, a separating device 7 consisting of a separating electrode and a separating claw, a cleaning device rf18, and an afterimage erasing device 1 are provided. 9 are arranged in sequence.

Before the arrival of the optical image on the photosensitive drum 2, the photoconductive layer 2 is charged uniformly, for example, by a charged electrode 5 to which a high DC voltage is applied, and the photoconductive layer in this state becomes the optical image. When exposed to light, the conductivity of the part that receives the light increases, and the electrical charge in that part escapes to the metal cylinder, leaving a positive charge in the dark part depending on the degree of brightness, and this causes the light to be absorbed. 6 The developing device 10 in this embodiment is a two-color developing device in which an electrostatic latent image corresponding to the image of the original is formed on the surface of the conductive layer, and includes an upper developing device 118 located on the upper side; , and the lower developing device 11B located below can swing together. On the other hand, a motor (not shown) is provided behind the pongee 12 located outside the developing device 1110.
The motor rotates when the color designation (developing device selection) button is selected, and the rotation of the motor causes the cam 1 fixed to the pongee 12 to rotate.
3 is designed to rotate.

The cam 13 then stops while pressing the contact portion 14^ or the contact portion 14B of the developing device filo. When the cam 13 presses the contact portion 14^, the developing device 10 is swung counterclockwise via the spring member 15^, and the developing sleeve serving as a developer carrier to the second developing unit 11 is moved. 111^
The photosensitive drum 2 is stopped at a position opposite to the surface of the photosensitive drum 2 with a preset small gap, and development is performed by the upper developing device 11^. Further, depending on another selection of the color designation (developing device selection) button, the cam 13 presses the contact portion 14B of the developing device rIt10, swings the developing device 10 clockwise via the spring member 15B, and The developing sleeve 111B, which is the developer carrier of the device 11B, is stopped at a position opposite to the surface of the photosensitive drum 2 with a preset small gap, and the lower developing device 11
Development with B is performed.

In this embodiment, the upper developing device 11^ contains two-component red developer containing red toner, and the lower developing device 11B contains two-component red developer containing black toner.
A component black developer is housed therein, and each two-component developer is uniformly stirred by a stirring member 112^ or 112B, and the toner is banded in a negative direction 11. In addition, for the red toner consumed by development in the upper developing device 11^, the red toner contained in the hopper 113A falls into the upper developing device 11^ by the rotation of the replenishment screw 114^, and the red toner is replenished. will be done. The same applies to the lower developing device 11B, but the hopper 1 containing black toner
138 is located on the front side of [t, where toner is replenished, so there is a hopper 113B and a replenishment screw 114B.
are not shown.

The portion of the photosensitive drum 2 on which the electrostatic latent image is formed is the developing sleeve 111^ of the upper developing device 11^ or the lower developing device 1.
When reaching the developing sleeve 111B portion 1B, negatively charged red toner or black toner is attracted to the remaining positively charged portion of the surface of the photosensitive drum 2 by electrostatic force. As a result,
A red toner image or a black toner image is formed on the surface of the photosensitive drum 2 according to the electrostatic latent image.

On the other hand, the transfer paper P in the cassette 21 selected by the transfer paper size selection button is fed out by the paper feed roller 22 at a timing such that its leading edge coincides with the leading edge of the toner image, and the transferred transfer paper P The toner image on the surface of the photosensitive drum 2 is transferred by the transfer electrode 6 to which a DC voltage is applied.

Thereafter, the transfer paper P is separated from the photosensitive drum 2 by a separating device 7 consisting of polarized poles and one separating claw to which AC high voltage is applied, and is sent to a fixing device (not shown) by a conveyor belt 23, where the toner image is fixed. , a receiver provided outside the recording device is discharged into a tray. Further, after the toner image is transferred to the photosensitive paper P-hi, the residual toner remaining on the circumferential surface of the photosensitive drum 2 is cleaned by a cleaning device 8, and the potential on the photosensitive drum 2 is maintained at a certain level by an afterimage erasing device 9. The next copy operation is possible.

tjS2 diagram shows the developing device 11^ and I of the developing device a10.
This figure shows the detailed structure of IB.

The magnetic roll 121 has a main magnet N with its N pole facing outward as a magnet for development on the outer peripheral surface of the Fulumi bar material.

and sub-magnets S1 and 82 with their S poles facing outward as a plurality of magnets for transporting developer; 11 facing outward like magnet N1
The main magnet N1 is provided with a magnet N2, and when the developing unit 11^ or 11B is oscillated by the rotation of the cam 13 mentioned above and set at the developing position, the main magnet N1 is oriented approximately 5 degrees upward from perpendicular to the surface of the photosensitive drum 2 ( (upstream side) to form a development area.

The photosensitive drum 2 has an aluminum drum support with an outer diameter of 100zzφ and a photoconductive layer of 5e-Te (selenium-tellurium) on the circumferential surface thereof.The photosensitive drum 2 has a circumferential speed of 1401 per second clockwise in FIG. 2. The above-mentioned charging electrode 5 is rotated by M.
is positively charged.

Also, both the developing sleeves 111^ and 111B have an outer diameter of 20z.
Wall thickness 0.7~0.8ii made of stainless steel with yφ
It is a thin-walled cylinder with a roughened outer surface using Sand Plus ($30), and is rotated counterclockwise in FIG. 2 at a circumferential speed 2.5 times that of the photosensitive drum 2. , when forming a visible image in the developing area, the distance (D, S, D) between the outer circumferential surface of the developing area and the outer circumferential surface of the photosensitive drum 2 is set to 0.5.
It is set to a position that keeps it at zz.

Further, at predetermined positions facing the outer circumferential surface of the upper developing sleeve 111^ and upper 1111B, a spike regulating plate 122^ or 122B is installed, respectively, with a predetermined gap therebetween.

The spike regulating plate 122^ upper 1122B controls a predetermined amount of developer, which is conveyed by adhering to the outer peripheral surface of the developing sleeve 111^ or 111B attracted by the magnetic force of each sub-magnet of the magnetic roll 121, to a predetermined amount. The developer is conveyed to the developing area with a thickness limited to the thickness of the developer, and in the developing area, the magnetic force of the main magnet N causes the developer to stand up to the required thickness to adhere to the electrostatic latent image on the photosensitive drum 2. The amount of developer is supplied.

In the image forming apparatus of the present invention, the DC bias voltage applied to each developing sleeve 111^ and 1111B of the developing device 11^ upper 111B is supplied from one bias power supply device through the wiring circuit shown in FIG. It is configured to do this.

That is, a connector plug for connecting to a bias power supply device installed separately from each developing device 11^ and the JIB is attached to the side surface of the container of the developing device 1]^ located on the upstream side of the rotation. The bias power supply device can be electrically connected to and separated from the developing device 11^ by attaching and detaching the socket on the bias power supply device side.

On the other hand, fixed contacts P^ and PB, which are elastically biased in the thrust direction, are in pressure contact with the end surfaces of the developing sleeves 111^ and 111[1, respectively.
In the case of 1^, the fixed contact P8 is directly connected to the plug of the connector, whereas in the developing device 11B, the fixed contact PB is indirectly connected to the plug of the connector via a banana jack, and the bias power supply is connected to the fixed contact P8. It constitutes a circuit.

Therefore, the bias power supply i device described above is used in the developing device 11^.
A DC bias voltage can be conducted and applied to both the two developing sleeves 111^ and 1118 of IIB as necessary.

Further, each of the processing and developing units 118 or 11B can be removed from the image forming apparatus using a bias voltage circuit by separating the connections between the connector and the banana jack described above, thereby simplifying the circuit wiring. year,
In addition, each developing unit is configured to be easily removed.

In the above embodiment, the bias power source is directly connected to a developing device located on the upstream side of the rotation, and a wiring circuit is configured in series from the developing device to other developing devices located on the downstream side of the rotation via an inter-device connection means. However, on the other hand, the bias power supply is directly connected to the beneficiary device located on the upstream side of the rotation, and the series It is also possible to configure a wiring circuit, which has the same effect as described above.

In this embodiment, an image forming apparatus including two developing devices it^ and 118 as a plurality of developing devices has been described, but the present invention is applicable to an image forming apparatus having a developing device equipped with three or more developing devices. It can also be applied by similar means.

〔Effect of the invention〕

According to the present invention, even in an image forming apparatus equipped with a plurality of developing devices, it is possible to apply a DC bias voltage to all developer carriers by simply installing one bias power supply device, and as a result, the power source This has resulted in the provision of an image forming apparatus that reduces the number of devices and simplifies the wiring route, resulting in a low failure rate and low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of an image forming apparatus according to the present invention. FIG. 2 is a sectional view of the developing device of the device. FIG. 3 is a bias voltage circuit diagram of the developing device. FIG. 4 is a conceptual diagram showing the operation of the developing device. 2... Photosensitive drum 10... Developing device 11^
, 11B...Developing device 111^, IIIB...Developing sleeve P^, pe...
・Fixed contact applicant: Konishiroku Photo Industry Co., Ltd. Figure 3 PAAl1

Claims (1)

[Claims] An image forming apparatus in which at least two developing devices are provided facing an image carrier, characterized in that a DC bias voltage to be applied to the developer carrier in the plurality of developing devices is supplied from one power supply device. Image forming device.