JPH03260676A - Image forming device - Google Patents

Abstract

PURPOSE:To effectively develop a desired latent image area by making almost all amount of thin-layered developer which passes the tip of an electrode piece into powder-cloud state by the action of strong electric field and forming uniform high-density cloud on a developing area. CONSTITUTION:By rotating a developer carrier 101 and a latent image carrier 2, toner is attracted to the carrier 101 and a thin developer layer 107 is formed by a regulating charging member 103. At the same time, the layer 107 is charged by the friction with the carrier 101 and the member 103. The layer 107 is carried under a stirring means 105 and variable electric field is added to the layer 107 by the electrode piece 105b, then it is carried while it moves back and forth violently between the carrier 101 and the electrode piece 105b by the strong electric field between both of them. The developer layer is sprung out by the strong electric field of the tip 105c to become powder-cloud PC and dispersed on the developing area R. The developer collides mutually to be charged. With such constitution, the desired latent image area is effectively developed because the uniform high-density cloud of toner is formed on the area R.

Description

[Detailed description of the invention] - No. 1! The present invention is an image forming apparatus that obtains an image by developing only a desired area of a latent image formed on a latent image carrier using a dry developer. The present invention can also be suitably implemented in a multicolor image forming apparatus in which a multicolor image is obtained by developing different latent images.

Conventionally, it has been extremely difficult to sharply develop a latent image portion in an arbitrary region of a latent image on a latent image carrier using a dry developing method. In conventional one-component developing devices, the two-component developer layer is thick, so even if the application area of the two-component developer layer on a developer carrier such as a developing roller is controlled by a mechanical shutter, etc. When a magnetic brush made of a two-component developer is pressed against a latent image carrier, the developed area becomes even more indistinct and expands, making it impossible or extremely difficult to sharply develop a latent image in an arbitrary area. Ta.

Many methods have been proposed to solve such problems. For example, in Japanese Patent Application Laid-open No. 60-214375,
A plurality of ring-shaped electrodes are arranged along the axial direction of the development roller, and a development bias voltage is applied between the latent image carrier and the electrodes based on the development width and development timing according to the desired development area. A method for developing the image is disclosed. However, with this method, it is not possible to form a sufficiently sharp development area to clearly develop any latent image portion on the latent image carrier, and therefore it has not yet been put to practical use.

Further, Japanese Patent Application Laid-Open No. 59-232363 discloses that a developer is applied only to an area on a developer carrier according to a coating signal, and
A method is disclosed for developing only an arbitrary area of a latent image on a latent image carrier. With this method, the developer can be sharply applied only to an arbitrary area on the developer carrier, but in the developing process facing the latent image, the sharp developed area formed on the developer carrier is slightly distorted. However, there was a problem in that it was difficult to develop a clear latent image.

Furthermore, in Japanese Patent Application Laid-open No. 61-39060, a developer is coated on a developer carrier, and the coated developer is coated with predetermined electrode needles arranged in the width direction of the developer carrier. A predetermined amount of charge is injected by applying a voltage to the electrode needles for a predetermined period of time, and the developer into which this charge is injected is made to face the latent image on the latent image carrier to develop only the predetermined region. A method is disclosed. However, with this method, it is extremely difficult to control the charge of the developer by charge injection, and if a low-resistance developer, which is easy to inject charge, is used, it is difficult to transfer the developed image to the transfer material. Problems arise.

On the other hand, in a color electrophotographic apparatus, there are several known methods for simultaneously obtaining multicolor images in -transfer steps, but these methods require that a latent image corresponding to each development be generated prior to the development step. It was necessary to form the latent image on the latent image carrier. That is, the conventional method cannot sharply develop any latent image area in the developing step, and therefore cannot be put to practical use as a simple multicolor image formation.

Therefore, the present applicant coated a thin layer of developer on a developer carrier, charged it, and placed a plate-shaped electrode near the development area so that its tip faced the development area. A variable electric field is generated between the electrode and the developer carrier by closely facing the developer carrier, and the developer is turned into a powder cloud and diffused into the development area at the tip of the electrode, forming a latent image on the latent image carrier. Develop,
An image forming device for obtaining images was proposed.

Such an image forming apparatus has the feature that the flight of the developer within the development area is spatially limited and that images with high sharpness can be obtained at high speed and with high efficiency.

The present invention relates to an improvement of such an image forming apparatus, which can obtain clear images, and can be particularly suitably implemented in a simple multicolor image forming apparatus.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus that can sharply develop only a desired area using a dry developer and obtain a clear image.

Another object of the present invention is to sharply develop only the desired development area of the same latent image in the development process, without forming separate latent images prior to the development process, and to develop a simple and practically usable latent image. An object of the present invention is to provide a multicolor image forming apparatus capable of obtaining a multicolor image.

The above-mentioned aspects for performing the following are completely achieved by the image forming apparatus according to the present invention. To summarize, the present invention provides an image forming apparatus that includes a latent image carrier on which a latent image is formed and a developing device that develops the latent image on the latent image carrier, wherein the developing device applies a developer. a developer carrier that carries the developer and transports it toward the latent image carrier; a regulating charging member that forms a thin layer of developer with a predetermined thickness on the developer carrier and charges the developer; a disturbance member divided into a plurality of parts in the width direction of the developer carrier, and a disturbance means disposed in contact with or close to the developer thin layer, and a disturbance member selected from the disturbance member. a driving means for generating a powder cloud of developer by driving an arbitrary disturbance member for a predetermined period of time; and a driving means for generating a powder cloud of developer in a non-image area of the latent image carrier toward the developer carrier. and an electric field generating means for generating an electric field for pulling back. Further, by providing two or more developing devices containing different developers and developing different regions of the latent image on the latent image carrier with each developing device, a multicolor image can be easily obtained.

1 Dish 1 Hereinafter, the image forming apparatus according to the present invention will be specifically described with reference to the drawings.

Referring to FIGS. 1 and 2, a latent image carrier 2 having an electrostatic latent image recording layer 201 is arranged on a cylindrical substrate 202 so as to be rotatable in the direction of the arrow. A developing device 1 is disposed opposite to.

In this embodiment, the developing device 1 has a hopper 104 containing the l-component developer, and a roller-shaped developer carrier 1 supported by a shaft 102 is disposed at the front opening of the hopper 104.
01 is provided and is rotationally driven in the direction of arrow a. Further, a regulating charging member 103 is provided at the upper edge of the front opening of the hopper 104.
Further, a disturbance means 105 is provided on the downstream side of the regulating charging member 103 in the rotational direction of the developer carrier 101 .

The disturbance means 105 is best illustrated in FIG. , has a plurality of disturbance members divided in the width direction of the developer carrier 101, that is, plate-shaped electrode pieces 105b in this embodiment.Furthermore, the proximal end side of the electrode piece 105b is attached to each terminal box 105x. , each tip edge 105c
is positioned so as to face into the development area R formed between the developer carrier 101 and the latent image carrier 2. In reality, the gap between the closest portion of the disturbance means 105 (indicated by C in FIG. 3) and the developer carrier 101 is 20 μm or less, and the gap between the developer carrier 101 and the developer carrier 101 in the development area R is The gap with the image carrier 2 is 50 to 500 μm, preferably 1
It is set to 00 to 300 μm.

According to this embodiment, as shown in FIG. 1, a DC voltage power source 3 is provided between the developer carrier 101 and the latent image carrier 2 as a developing bias power source, An AC power source 106 for a fluctuating electric field is arranged between the body 101 and the disturbance means 105. To explain further, as understood from FIG. 2, the AC power supply 106 is connected to the switch SW
(SW,,SW,,SW,,5W4SW,,... ・
) to each electrode piece 105b, and each electrode piece 10
5 is driven, that is, a varying voltage is applied.

With this configuration, when the developer carrier 101 rotates in the direction of the arrow a and the latent image carrier 2 rotates in the direction of the arrow, the toner in the hopper 104 is electrostatically or , is magnetically adsorbed onto the developer carrier 101 and brought to the regulating charging member 103, where it is regulated to an appropriate layer thickness, usually a thickness of several layers, to form a thin developer layer. 107 is formed. At the same time, the thin developer layer 107 is transferred to the developer carrier 101. It is charged by frictional charging with the regulating charging member 103 and the like.

The thin developer layer 107 is then brought under the agitation means 105 and the corresponding electrode piece 10 is turned on with the switch SW turned on.
A fluctuating electric field is applied by 5b.

To further explain with reference to FIG. 3, the developer carrier 101
The upper developer thin layer 107 is brought to the agitating means 105, and on the downstream side in the rotational direction of the developer carrier 101 from the closest point or contact point C, the developer carrier], Ol is selected. Due to the strong electric field formed between the electrode piece 105b, the electrode piece 105b moves violently back and forth between the two in a free space t whose thickness is greater than the thickness of the thin developer layer 107, and finally the electrode piece 105b It is repelled by the strong electric field of the tip 105C of the electrode piece, and from the point where it leaves the tip 105c of the electrode piece, it becomes a powder cloud (PC) and is dispersed in the developing area R.

Also, due to the intense reciprocating motion in free space, the developer collides with each other and becomes electrically charged. Although collisional charging is not the main charging effect of the developer in the present invention, it is considered to be one of the factors for achieving stable charging.

According to the present invention, due to this strong electric field action, almost the entire amount of the thin developer layer 107 that has passed through the tip of the electrode piece contributes to the formation of a powder cloud, so that a uniform and high concentration powder cloud is formed in the development area R. is formed, effectively developing the desired latent image area.

As understood from the above description, the disturbance means 105 is arranged near the development area, and the fluctuating electric field applied between the electrode piece 105b and the developer carrier 101 substantially affects the development action. There isn't. Therefore, according to the present invention, in the development region R, the development bias only needs to be applied mainly for development (this makes it possible to set the development bias optimally for development.

Further, in order to further reduce the influence of the fluctuating electric field on the development region R, it is also possible to provide a shield electrode on the side of the electrode piece 105b facing the latent image carrier 2.

Powder cloud-like developer P formed in this way
C represents the electric field of the latent image on the latent image carrier 2 and the powder cloud-like developer PC in the non-image area on the developer carrier 10.
It moves along the combined electric field with the electric field generated by the electric field generating means, that is, the electric field generated by the developing bias power supply 3, which generates an electric field in the direction of pulling back toward the first direction, and adheres to the latent image on the latent image carrier 2, thereby achieving development. . The developer corresponding to the non-image area is deposited on the developer carrier again and collected. Thereafter, similar processes are performed as the developer carrier 101 rotates, and continuous development is performed.

In this embodiment, the regulating charging member 103 is
-43038 publication, JP-A-60-83648 publication,
JP-A-60-73649, JP-A-61-1389
The blade is a metal blade, a rubber blade, or the like as described in Japanese Patent Publication No. 67, Japanese Patent Laid-Open No. 62-24283, etc., and is in pressure contact with the developer carrier 101. The effect of frictional forces between the blades,
The developer is charged while forming a thin layer of developer on the developer carrier 101, taking into consideration the effects of triboelectric charging and frictional charging.

Moreover, instead of using the above-mentioned blade as the regulating charging member 103, the regulating charging member 103 is disclosed in Japanese Patent Application Laid-open No. 56-123555 and Japanese Patent Application Laid-open No. 61-2.
It is also possible to use a roller-shaped member as disclosed in Japanese Patent No. 19066, etc., which presses against the developer carrier 101 in the same manner as the blade. The developer can be charged while forming a thin layer of developer on the developer carrier 101, taking into consideration the effects of frictional force between the developer and the rollers, and the effect of frictional charging.

Furthermore, as the regulating charging member 103, Japanese Patent Application Laid-Open No. 54-4
As seen in Japanese Patent No. 3037, it can also be constructed of a magnet fixedly arranged inside the developer carrier and a magnetic blade arranged close to the developer carrier. With this configuration, consideration is given to the effect of the magnetic field generated between the magnet and the magnetic blade, the effect of the frictional force between the developer carrier 101, the developer, and the magnetic blade, and the effect of frictional charging.
In addition to forming a thin layer of developer on the developer carrier 101, the developer can be charged.

Note that the developer carrier 101 is connected to the regulating charging member 103.
Generally, the thickness of 0.1 to several tens of micrometers is selected in relation to the
A material with a certain degree of unevenness is used.

Further, the electrode piece 105b of the disturbance means 105 has Aff, S
Is it made of a metal thin plate such as US, phosphor bronze, or copper?
Alternatively, a thin metal layer may be formed on the insulating substrate 105a, and the thin metal layer may be divided into a plurality of parts and patterned by etching or other processing. Insulating substrate 10
As described above, 5a is appropriately selected from a material such as a Mylar sheet that is preferable for charging the developer to a desired polarity, or a material that does not adversely affect charging.

FIG. 4 shows another embodiment of the invention. According to this embodiment, the disturbance means 105 is configured to also serve as the regulating charging member 103 in the embodiment shown in FIG.

That is, the disturbance means 103 includes an elastic rubber sheet 108a disposed over the entire width of the developer carrier 101, and an elastic rubber sheet 108a provided on the elastic rubber sheet 108a.
It has a plurality of disturbance members divided in the width direction, that is, plate-shaped electrode pieces 108b. Although not shown in FIG. 4, the base end side of the electrode piece 105b is connected to the AC power source 106 via each terminal box 105x and switch SW, as in the embodiment shown in FIG.

According to this embodiment, the disturbance means 103
A thin layer of developer is formed on 01, the developer is charged at the same time, and a fluctuating electric field is generated via the electrode piece 108b to form a powder cloud of the developer in the same manner as described above. to occur.

FIG. 5 shows yet another embodiment of the developing device according to the present invention.

In this embodiment, the disturbance means 105 includes a plate-shaped vibrating piece 10
9 (109a, 109b, 109c, 109d, 10
9e,...), each vibrating piece 10
The base end of 9 is a vibration source 110 (110a) consisting of an electrostrictive element.
, 110b, 110c, 110d, 110e,...)
are connected to each. Further, the vibration source 110 includes switches SW (SWI, SW2, SW3, SW4, SW5,
), and is connected to a vibration power source 111 having a frequency of, for example, 400 Hz, and is driven.

Therefore, the corresponding vibration source 110 whose switch SW is turned on
When driven, it causes the connected vibrating piece 109 to vibrate. The vibration of the vibrating piece 109 causes the vibrating piece 10
The tip of the developer 9 hits the thin developer layer 107 on the surface of the developer carrier 101, causing the developer to fly and form a powder cloud. The developer in the form of a powder cloud is introduced into the development area R in the same manner as in the above-described embodiment, and the desired latent image area can be sharply developed.

In this embodiment, regarding the developer in the form of a powder cloud, regarding the non-image area, the developer carrier 101
Since it is necessary to pull it back to the side, a developing bias of, for example, 80V is applied.

FIG. 6 shows an embodiment in which the present invention is embodied in an electrophotographic copying machine.

In this embodiment, a document mounting table 501 made of a transparent member is horizontally reciprocated, and a short focus and small diameter imaging element array 502
An image is read from a document on a document table 501 and placed on the latent image carrier 2 for slit exposure. Although the latent image carrier 2 is shown as a drum-shaped photoreceptor in this embodiment,
It may also be an endlessly moving web.

The latent image carrier 2 is charged by a charger 504 prior to exposure, and the latent image formed on the latent image carrier 2 is turned into a toner image by the developing device 1 having the above configuration. The transfer paper P is moved by the registration roller 507 in synchronization with the image on the latent image carrier 2.
The toner image is transferred onto the latent image carrier P by the action of the transfer charger 508. Thereafter, the transfer paper P is separated and guided to a fixing device 510 by a guide 509, where it is subjected to a fixing process and then discharged onto a tray by a paper discharge roller 511.

FIG. 7 shows an embodiment in which the present invention is embodied in a multicolor electrophotographic copying machine.

In this embodiment, unlike the embodiment shown in FIG. 6, two sets of developing devices 1 are prepared, divided into IA and IB. For example, red toner is stored in the developing device IA, and red toner is stored in the developing device IB.
Blue toner is used for each.

Here, as described above, the developing devices IA and IB are each equipped with a disturbance means having the above-mentioned configuration, and by operating desired electrode pieces of the disturbance means, each developing device is applied to different areas at different times. The developer is sent flying,
Different areas of the same latent image on a latent image carrier 2 such as an electrophotographic photoreceptor are developed.

As a result, two-color recording was obtained using the same latent image in one transfer. According to this example, subsequent development was achieved without disturbing the previously developed developer, and different developers did not mix colors. Moreover, the boundaries of each desired development area were sharp and satisfactory. By increasing the number of developing devices and using developers of other colors, more multicolor records can be obtained from one latent image.

The rest of the configuration in this embodiment is the same as that in the embodiment shown in FIG. 6, so a description thereof will be omitted.

In such a configuration, especially in the embodiment of FIG.
In each developing device, the developer that has become a powder cloud is collected by an electric field that pulls it back to the developer carrier, so color mixing to the next developing device is avoided, which is extremely convenient.

Next, some aspects of actual use of the present invention will be described in more detail.

(Example 1) A developing device 1 having the configuration shown in FIG. 1 was applied to an electrophotographic copying machine shown in FIG. 6 to produce an image.

The developer carrier 101 is a SUS roll having a diameter of 20 mm, and its surface is roughened by sandblasting to have a roughness of 1 to 2 μm in JISIO point average roughness (JIS-BO610). The regulating charging member 103 was a phosphor bronze plate with a thickness of 0.2 mm, and was brought into contact with the surface of the developer carrier 101 with a pressure of approximately 100 g/cm.

A developer containing a polyester resin, a charge control agent, a coloring pigment, etc. and having a number average particle size of approximately 12 μm is charged into the hopper 104, and the developer carrying member 10
1 was rotated at a circumferential speed of 100 mm/s. by this,
A charged thin layer of developer (thickness of about 2 to 3 developer particles) was formed on developer carrier 101 .

The disturbance means 105 is a Mylar sheet 10 with a thickness of 150 μm.
Electrode pieces 105b made of A1 foil having a thickness of 50 μm and a width of 2 mm were arranged on the electrode 5a at a distance of 300 μm from each other. Further, the tip 105c of the electrode piece 105b was arranged to be located in or near the development area. At this time, the distance between the tip edge 105c of the electrode piece 105b and the developer carrier 101 was 20 μm.

As the AC power supply 106, an AC power supply with a voltage Vp-p of 700 .mu., a frequency of 5 KHz, and a sine wave was used.

With this configuration, when voltage was applied to each electrode piece 105b, the tip 1 of the switched-on electrode piece 105b
A powder cloud of developer was generated near 05c and spread in the development area.

As the latent image carrier 2, an organic semiconductor (OPC) was used to form a latent image of +20 V in bright areas and +530 V in dark areas. The distance between the latent image carrier 2 and the developer carrier 101 is approximately 0.5 mm.
, and the developer powder cloud PC is used in the non-image area.
A DC bias of 50 V was applied to draw the developer back to the developer carrier 101. Note that the moving speed of the image carrier was the same as that of the developer carrier.

According to this example, only the desired area of the latent image on the latent image carrier corresponding to the selected electrode piece was sharply developed, and a clear image could be obtained.

(Example 2) The configuration was similar to that of Example 1, but 50 V DC was added to the AC power supply 106 as a bias component.

As in Example 1, the results showed that a clear image with sufficiently high density was obtained only in the desired area, with sharp boundaries between the areas, and the presence of developer adhering to the electrode body 105b was significantly reduced. Diminished.

The developing width of the latent image carrier in the circumferential direction was approximately 1 mm at the minimum.

(Example 3) The developing device 1 having the configuration shown in FIG. 4 was applied to an electrophotographic copying machine shown in FIG. 6 to produce an image.

In this embodiment, the disturbance means 1 also serves as a developer regulating charging member.
In No. 05, an electrode piece 105b was formed from a phosphor bronze thin plate having a thickness of 0.2 mm and a width of 2 mm, and was attached to an elastic rubber sheet having a thickness of 0.1 mm at a distance of 300 μm from each other.

Further, the disturbance means 105 applies approximately 150 g/c to the developer carrier.
The gap between the tip and the developer carrier was set to be 20 μm.

Images were produced under the same conditions as in Example 1.

As in Example 1, a clear image could be obtained in the desired sharp region.

The present invention is not limited to the above embodiments, but can be modified in various ways, and suitable conditions are set depending on the configuration, materials used, etc. For example, as a power source for applying an electric field between the latent image carrier and the electrode piece, a voltage of 100 to
The waveform can be 1000 Vp-p, the frequency is 1 to 10 KHz, and the waveform can be a triangular wave, a rectangular wave, a pulsating wave, a pulse train wave, or other distorted wave, and it is also possible to use a waveform in which a DC component is superimposed thereon.

Further, the present invention can be applied not only to non-magnetic developers but also to magnetic developers, and can be applied not only to electrostatic latent images but also to development of magnetic latent images.

As explained above, the image forming apparatus according to the present invention sharply develops only a desired area using a dry developer.
It is possible to obtain a clear image, and without forming separate latent images prior to the development process (the same latent image can be sharply developed in only the desired development area in the development process, making it possible to use it for practical purposes). It has the advantage of being able to easily obtain multicolor images.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is an enlarged perspective view of essential parts of a developing device constructed according to the present invention. FIG. 3 is a side view of essential parts of a developing device constructed according to the present invention. FIG. 4 is a schematic configuration diagram showing another embodiment of the image forming apparatus according to the present invention. FIG. 5 is a perspective view of essential parts of a developing device according to another embodiment of the present invention. 6 and 7 are schematic configuration diagrams of specific examples in which the present invention is applied to an electrophotographic copying machine, respectively. 2: Latent image carrier 3: Electric field generating means 01: Developer carrier 03: Regulation charging means 05: Disturbing means 05b, 108b, 109: Disturbing member 07: Developer thin layer 06.111: Driving means FIG. Figure 4 Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1) An image forming apparatus including a latent image carrier on which a latent image is formed, and a developing device that develops the latent image on the latent image carrier, wherein the developing device includes a developer. a developer carrier that carries a developer and transports the latent image carrier toward the latent image carrier; and a regulating charging member that forms a thin developer layer of a predetermined thickness on the developer carrier and charges the developer. , a disturbance member divided into a plurality of parts in the width direction of the developer carrier, and a disturbance means disposed in contact with or close to the developer thin layer; and a selection from the disturbance members. driving means for generating a powder cloud of developer by driving any disturbance member for a predetermined period of time; An image forming apparatus comprising an electric field generating means for generating an electric field for pulling back the image. 2) Equipped with two or more developing devices containing different developers,
2. The image forming apparatus according to claim 1, wherein each developing device develops the latent image on the latent image carrier to obtain a multicolor image.