JPS63133172A - Developing device - Google Patents

Abstract

PURPOSE:To simplify and miniaturize a developing device and uniformly and stably give the electric charge to a toner for a long time by applying a unidirectional potential between a conductive holding member of the toner and a conductive rotating cylindrical control member. CONSTITUTION:A conductive rotating cylindrical control member 28 which is combined with a conductive holding member 2 to form a control gap and controls the toner layer thickness while giving turbulence to the toner layer to agitate it is arranged in the side part of the conductive holding member 2 of the toner. A DC power source 32 to apply the unidirectional potential is connected between the conductive holding member 2 of the toner and the conductive rotating cylindrical control member 28, and the bias voltage from a DC power source 33 is given between the set surface of a photosensitive drum 4 and the conductive holding member 2 of the toner so that the toner is not stuck to a non-image part of the photosensitive drum 4. Thus, the toner is sufficiently stably electrified and the developing device is miniaturized, and scattering of the toner is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a developing device using -component magnetic toner.
In particular, the present invention relates to a developing device such as a copying device or a printing device using electrophotography.

2. Description of the Related Art Various proposals have been made for developing systems using monocomponent magnetic toner in electrophotographic copying devices, printing devices, and the like. - An advantage or essential requirement of the recent trend in the component magnetic toner development method is that compared to the so-called two-component development method, a developing device can be made simpler and more compact because a zero toner/carrier mixing ratio control mechanism is not required.

Therefore, during maintenance, it is possible to perform maintenance by replacing the developing device, and a user maintenance method can be adopted.

To provide sufficient developing ability only by low-speed rotation of a toner holding member by keeping a multipolar magnet contained in the toner holding member stationary. In other words, the amount of toner scattered from the toner holding member is sufficiently low, the inside of the copying device is less contaminated, and the period of mincing by a service person can be maintained for a sufficiently long period of time.

etc. are listed.

On the other hand, in order to enjoy and satisfy these advantages or essential requirements, the problem is how to sufficiently charge a one-component magnetic toner compared to a two-component development system.

British Patent No. 1, 396, 979 as shown in Fig. 3 is a developing method for a one-component magnetic toner that satisfies the above requirements.
An injection charging method is known in which the toner is physically disturbed under a high electric field.

In this method, one-component high-resistance magnetic toner 1 supplied in a box body 36 is applied to the surface of a copper rotating cylinder 35 containing a stationary multipolar magnet 34 while regulating the layer thickness with a blade 38. Under a high electric field between the copper rotating cylinder 35 and the rotating donor 39 formed by a voltage source 40, a rotating donor 39 made of a copper cylinder is held in a layer so that the toner is rubbed in one layer. , rotating cylinder 3
5 and the surface of the rotating donor 39, the toner is charged and moved while being disturbed, and then the charged toner is transferred to the electrostatic charge of the photoreceptor film 43 formed on the surface of the conductive rotating drum 42. The latent image is moved to the latent image and brought into contact with it under a bias from the voltage source 41, thereby making the latent image visible. Although this method is noteworthy as a charging method for -component magnetic toner, there are few examples of it being put into practical use because the structure is complicated and the toner tends to scatter from the donor surface. As an improved version of this method, U.S. Patent 4,
No. 121,931 was seen and put into practical use for a time, but because the voltage source for forming a high electric field was determined by the latent image voltage of the photoreceptor film, the toner was not sufficiently charged, and the toner was not fully charged. Since more disturbance is sought from the difference in surface running speed between the photoreceptor film and the toner holding member, toner scattering is not necessarily small, and therefore the situation is not desirable in terms of image quality or maintenance. Furthermore, Japanese Patent Laid-Open No. 117432/1987 is a publication that utilizes this type of charging method, in which injection charging is attempted by applying a high voltage between the toner holding member and the blade. Since the disturbance must be caused by the rotation of the toner holding member, it is questionable whether toner charging and toner scattering prevention can be achieved at the same time.

Problems to be Solved by the Invention As mentioned above, in the development method of one-component magnetic toner using the injection charging method, there are some advantages of the one-component development method, such as the development device becomes complicated and the toner cannot be sufficiently charged. In many cases, the structure is such that it impairs the quality of the image forming process, thus failing to meet the essential requirements for modern development methods.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a developing device that can simplify and downsize the developing device, and can uniformly and stably impart charge to toner over a long period of time. It is.

Means for Solving the Problems In order to solve the above problems, the developing device of the present invention is a developing device that rubs magnetic toner on the surface of an image bearing member, and comprises:
a toner conductive holding member that rotates while holding the toner on its surface for rubbing with the magnetic toner; a magnetic field generating means disposed on the back side of the toner conductive holding member; and a toner conductive member. an electrically conductive rotating cylindrical regulating member disposed close to the surface of the magnetic field generating means in a range covered by the magnetic field from the magnetic field generating means for disturbing the magnetic toner and thinning the magnetic toner; , a configuration in which a unidirectional potential is applied between the conductive toner holding member and the conductive rotating cylindrical regulating member.

According to the above-described structure, the present invention allows the magnetic toner held by the toner conductive holding member to be raised between the toner conductive holding member and the conductive rotating cylindrical regulating member while raising the toner by the action of a magnetic field. Because the toner is rapidly agitated by a mechanical system independent of the toner holding member under a high electric field, it is possible to inject sufficient toner and prevent toner from scattering, and the developing device can be simplified and miniaturized. It is possible to satisfy the essential requirements of the one-component development method.

Embodiment Hereinafter, one embodiment of the present invention will be described in detail based on the attached drawings. FIG. 2 is an internal structural diagram showing an example of a copying machine using electrophotography to which the developing device of the present invention is applied. In the figure, reference numeral 5 denotes a main body of the copying apparatus, and an image carrier, specifically a photosensitive drum 4, is provided approximately at the center of the main body so as to be driven to rotate in the direction of the arrow. drum 4
Surroundings are a charging charger 6, a developing device 7. Transfer charger 89 Separation charger 9. Cleaning equipment N10. Static elimination lamps 11 are sequentially disposed in the rotational direction of the photosensitive drum 4 as shown by the arrow, and operate as the drum 4 rotates to remove toner onto the transfer paper that is conveyed in synchronization with the rotation of the drum 4. It constitutes the main image forming means and transfer means of the image forming section that transfers images.

This image forming section cleans the photosensitive drum 4 using a cleaning device 10.
After cleaning and removing static electricity using the static eliminating lamp 11, the electric charge is charged using the charging charger 6. drum 4
This charged surface is exposed to light by the image of the original placed on the original placing glass 13 on the main body 5 through the scanning optical system 12, forming an electrostatic latent image, which is then transferred to the developing device. The main parts are constituted by an image forming means for developing toner by means of a transfer charger 8, and a transfer means for transferring the developed toner image onto a transfer paper fed in synchronization with a transfer charger 8. Further, the transfer paper after the transfer is separated from the surface of the drum 4 by a separation charge +9. The surface of the drum 40 after the transfer from which the transfer paper has been separated returns to its initial state after residual toner is scraped off by the cleaning device 10.

Reference numeral 14 denotes a document cover, which is attached to the main body 5 so that it can be opened and closed with respect to the document placement glass 13. 15 is an imaging lens of the scanning optical system.

On the left side of the image forming section, there is a paper feeding means for feeding the transfer paper to the transfer means, and on the right side there is a conveying means for carrying the transfer paper separated from the drum 4 after the transfer, and a heat-fusing means to heat and fuse the transferred toner image on the transfer paper. heating fixing means 16. A paper ejecting section for ejecting the transfer paper that has passed through the fixing means 16 is provided to constitute an electronic copying apparatus. The paper feed section includes a paper feed cassette 18.
The paper feed cassette 19 is attached to the copying apparatus main body 5 so as to protrude from one side, and by selectively driving the paper feed rollers 20, 21 and the guide plate 22, the paper is transferred from one side of the paper feed center 18 and 19. The paper is sent to the Quiminogroller 23 and sent to the transfer means below the photoreceptor drum 4 in synchronization with the movement of the toner image on the photoreceptor drum 4. In the paper discharge section, the transfer sheets discharged from the fixing means 16 are stacked and stored in a paper discharge tray 25 through a paper discharge roll 24.

The above is an example of a copying apparatus to which a developing device according to the present invention is applied.

FIG. 1 is an internal structural diagram showing a developing device when the present invention is applied to the above-mentioned electrophotographic copying apparatus.

In FIG. 1, the surface of the image carrier 4 is made of acrylic.

A thin layer 1 of a high-resistance component magnetic toner having an average particle diameter of about 10 μm is rubbed by mixing and dispersing magnetic powder such as ferrite as a main component in a resin such as styrene or polyester and pulverizing the mixture. This single layer of magnetic toner is held on the circumferential surface of a non-magnetic cylindrical conductive toner holding member 2 that is rotatably supported and driven to rotate in the direction of the arrow, and is conveyed to the surface of the image carrier 4. Ru.

A hopper 26 for storing magnetic toner and replenishing the circumferential surface of the toner holding member in a predetermined amount is disposed near the outside of the circumferential surface of the toner conductive holding member 2. Hopper 2
A toner supply port 27 is provided at one end of the toner replenishment port 27, and a toner replenishment port 27 is provided at one end of the toner replenishment port 27, and a toner replenishment port 27 is provided at the other end of the toner replenishment port 27, which is disposed close to the circumferential surface of the conductive toner holding member 2 to receive and collect toner remaining after rubbing the image carrier 4. It constitutes a rim 29. On the side of the toner conductive holding member 2,
In combination with the conductive holding member 2, a conductive rotating cylindrical restricting member 28 is provided which forms a restricting gap and regulates the thickness of the toner while giving a turbulent flow to the toner and disturbing it. The regulation gap between the cylindrical surface of the conductive rotating cylindrical regulating member 28 and the circumferential surface of the toner conductive holding member 2 is determined by the required toner thickness and the material of which the conductive rotating cylindrical regulating member 28 is made of magnetic material. Furthermore, it depends on the speed difference between the circumferential surface of the conductive toner holding member and the circumferential surface of the conductive rotating cylindrical regulating member 28. If you want to obtain a constant toner thickness, the material of the member 28 When it is magnetic, it tends to be wide, while when it is non-magnetic, it tends to be narrow. And the value is approximately 1.0
~0.2mm. Although the circumferential surface of the conductive rotating cylindrical regulating member 28 is not a necessary member in terms of wood, the toner adhering to the surface is constantly scraped off so that stable contact can be maintained between the surface and the toner surface. , a scraper 30 for cleaning is abutted on the member 28 in a circumferential tangential direction. A multi-polar permanent magnet 31 with stationary magnetic poles is fixed inside the cylindrical circumferential surface of the conductive toner holding member 2 in order to brush-like a single layer of magnetic toner held on the circumferential surface of the conductive holding member 2. has been done. The magnetic pole faces the image carrier 4 at a position where a single layer of brush-like toner can rub against the image carrier 4, and faces the conductive rotating cylindrical regulating member 28 at a position where a single layer of toner stands up like a brush. One layer member 28
The toner is disposed at a position where it can be disturbed by the rotation of the toner and further regulate the thickness of the toner. In addition, in this embodiment, a magnetic pole is also provided at a portion corresponding to the lower part of the toner hopper 26 in order to facilitate supply of magnetic toner onto the conductive toner holding member 2. A DC power supply 32 is connected between the toner conductive holding member 2 and the conductive rotating cylindrical regulating member 28 in order to apply a unidirectional potential. A bias voltage is applied between the holding members 2 by a DC power source 33 so that toner does not adhere to the non-image area of the photosensitive drum 4.

Next, the above embodiment will be further explained with the addition of specific data. The image carrier 4 may be a selenium drum, an organic photoreceptor drum, or a belt as a photoreceptor; here, a functionally separated organic photoreceptor drum is used. The surface charging voltage was -750 V, and the circumferential speed was 150 m/See. The magnetic toner is prepared by mixing and dispersing and pulverizing average particles by a well-known method in a ratio of, for example, 62 parts of acrylic-styrene resin, 32.5 parts of magnetite, 3 parts of charge control agent, 2 parts of carbon, and 0.5 part of stearic acid. A diameter of 10μ was used. Note that the toner is not limited to the above composition. As the toner conductive holding member 2, a non-magnetic stainless steel cylindrical material with a diameter of 3011 mm is used in the state shown in FIG. The surface magnetic flux density was used. Conductive rotating cylindrical regulating member 28
A magnetic stainless steel cylindrical material with a diameter of 12 mm was used. The gap Q between the conductive holding member 2 and the conductive rotating cylindrical regulating member 28 was selected to be 5 mm, and the gap between the image carrier 4, that is, the photosensitive drum and the surface of the toner holding member, was selected to be 0.4 fl. The circumferential speed of the conductive holding member 2 is the same in the same direction as the circumferential speed of the photoreceptor drum 4, so that toner does not scatter from the surface of the holding member, and the amount of toner necessary for development can be supplied to the latent image on the photoreceptor. You can select the circumferential speed. The circumferential speed of the conductive rotating cylindrical regulating member 28 can be selected independently from other components so that the toner layer can be sufficiently disturbed mechanically; here, the circumferential speed of the conductive holding member 2 and The same is true in the opposite direction. In addition, a toner conductive holding member 2 and a conductive rotating cylindrical regulating member 28 are provided.
700 as a unidirectional potential between the DC power source 32 and the opposite polarity to the surface potential of the photoreceptor drum 4 with respect to the toner conductive holding member 2, that is, a positive potential.
(2) was applied to the conductive rotating cylindrical regulating member 28. In addition,
In this embodiment, the polarity of the potential applied to each member is determined as the regular development condition, but this is not necessarily the case in the case of reversal development.

Under the conditions described above, the toner layer is in a state where it can be brushed and rubbed on the surface of the photoreceptor by the action of the magnetic field. At this time, the amount of charge of the toner that had reached the development position was measured, and the initial value was 10.9 to +12.4 μC/g. Under these conditions, in order to prevent toner from adhering to the non-image area of the photoreceptor drum 4, a DC power supply 33 of -150 V is applied to the conductive toner holding member 2 with reference to the conductive base of the photoreceptor film of the photoreceptor drum 4. A biased copy test was conducted. In the copying test, magnetic toner 2 was
Although the process was carried out to the extent of consuming 1.5 kg, the original image quality of the copied image was maintained, and a high-resolution image with little background fog was obtained. Further, the charge amount of toner 1 to toner when 2 kg of toner was consumed was +1.0.5 to +13.4 μC/g, which was a stable value that was almost the same as the initial value.

Effects of the Invention As described above, the present invention provides a developing device using -component high resistance magnetic toner, in which the magnetic toner held in the toner conductive holding member is transferred between the toner conductive holding member and the conductive rotating cylinder. The toner is injected and charged while providing magnetic turbulence under a high electric field and disturbance by a mechanically independent rotating cylindrical member in the gap between the shape regulating member and the toner thickness. This exhibits the effects of stable toner charging, miniaturization of the developing device, and suppression of toner scattering, thereby providing a copying device with excellent image quality without background blur.

[Brief explanation of the drawing]

FIG. 1 is an internal structural diagram showing a developing device according to an embodiment of the present invention applied to an electrophotographic copying device, and FIG. 2 is a diagram of a copying device using an electrophotographic method to which the developing device of the present invention is applied. FIG. 3 is a diagram illustrating an example of the internal configuration of a conventional developing device. 2... Conductive holding member for toner, 4...
・Photoconductor drum, 26...Hopper, 28...
. . . Conductive rotating cylindrical regulating member, 30 . . . Scraper.

Claims (1)

[Claims] A developing device that supplies a thin layer of magnetic toner in order to rub the surface of an image carrier with the magnetic toner, the toner rotating while holding the toner on its surface in order to rub the magnetic toner. a conductive holding member, a magnetic field generating means disposed on the back side of the toner conductive holding member, and a magnetic field generating means disposed close to the surface of the holding member in a range covered by the magnetic field from the magnetic field generating means. The magnetic toner has at least a conductive rotating cylindrical regulating member for agitating the magnetic toner to form a thin layer, and a unidirectional potential is applied between the toner conductive holding member and the conductive rotating cylindrical regulating member. A developing device characterized by: