JPS6095571A - Developing device - Google Patents

Abstract

PURPOSE:To develop a latent image on the surface of a latent image holding body sharply with good resolution by providing a developer supply container, developer holding member, magnetic particle restraining member, fixed magnetic field generating means, and magnetic particle circulation area limiting member. CONSTITUTION:A developing sleeve 12 is a nonmagnetic sleeve made of, for example, aluminum; its right half circumferential surface is intruded into a laterally long opening formed at the lower part of the left wall of the developer supply container 14 in the lengthwise direction of the container, and the left half circumferential surface is exposed outside of the container and borne laterally and rotatably. The reverse surface of the magnetic particle circulation area limiting member 27 contacts the top surface side of a magnetic blade 23 and the front end surface 27a is an undercut surface. While magnetic particles 20 and a nonmagnetic developer 24 are charged in the container 14, a magnetic brush 20a of magnetic particles is formed at a magnetic particle magnetic attracting layer part near the sleeve surface corresponding to the position of the magnetic pole 17 of a magnet 13 with the intense magnetic field of the magnetic pole 17.

Description

[Detailed Description of the Invention] The present invention provides a method for forming a latent image on the surface of a photoreceptor, dielectric, magnetic material, etc. using a conventionally known appropriate principle process such as electrophotography, electrostatic recording, magnetic recording, etc. The present invention relates to a developing device that visualizes an electrical latent image such as an electrostatic latent image ψ magnetic latent image using a dry developer (toner).

More specifically, the dry developer is formed and held as a thin layer on the surface of a developer holding member, and the thin developer layer forming and holding surface of the member is faced to the latent image holding member surface with a small gap, and a developing bias is applied. A method in which a thin layer of developer is selectively transferred and adhered to the latent image pattern on the latent image holding member side to develop the latent image (so-called jumping method), or a method for developing the latent image on the surface of the developer holding member. The present invention relates to a developing device of a type (contact type) that also develops a latent image by bringing a thin layer of agent into contact with the surface of an image carrier.

A developing device in which the developer is formed and held as a thin layer on the surface of the developer holding member and applied to the surface of the latent image holding member uses a magnetic developer as the developer, and the magnetic developer is applied to the surface of the latent image holding member. Various types of 4M have been proposed (for example, Japanese Patent Application Laid-Open No. 54-43037, etc.) in which a thin layer of uniform thickness is formed and maintained at each part using a layer thickness regulator and a layer thickness regulator, and is applied to the surface of a latent image carrier. has been done.

However, in this type of developing device, a magnetic material must be added to the developer in order to make the magnetic developer magnetic. Poor fixing performance when thermally fixing images.

Further, since the magnetic material is usually black, it is difficult to obtain a toner with a clear color, and there are problems such as poor color reproducibility in color copying.

Therefore, a non-magnetic developer is used as the developer, and the method of forming a thin layer of the non-magnetic developer is to use a cylindrical brush made of soft hair like beaver's hair and apply the developer to the brush. A method has been proposed in which the agent is applied to a developing roller made of fiber such as velvet using a doctor blade or the like.

However, “Second Book #j! If an elastic blade is used as a doctor blade for the m brush, it is possible to regulate the amount of developer, but uniform application is not achieved and the developing roller 4
Second! There is a problem in that fogging is likely to occur because the developer existing between the fibers of the brush is not triboelectrically charged even when the a-fiber brush is rubbed.

The present invention has been developed and proposed in view of the above, and uses a non-magnetic developer as a developer, and uses a novel thin layer forming method to apply a 1ljf developer to the lunar surface of the holding part uniformly and The formed body 11y can be formed as a thin layer, and the thin layer can be formed stably over the entire area. The object of this invention is to provide a developing device that can always stably produce a developed image or a photographic image that is good in color consideration/1. The gist is the developing device and configuration based on the scope I7.

A detailed explanation will be given below based on the embodiment H of the present invention shown in the drawings. FIG. 1 is a cross-sectional side view of four parts of the embodiment H. In the figure, 141 is a cursed image side supply container, and 12 is a developing sleeve with a developer amount of 1 and a Y portion layer.

The developing sleeve 12 is, for example, a non-magnetic sleeve made of aluminum or the like, and has a horizontally elongated opening formed in the lower part of the left side wall of the developer supply container 14 in the longitudinal direction of the container.

The right half-circumferential surface protrudes into the container 14, and the left half-circumferential surface is exposed to the outside of the container, so that it is freely rotatably mounted on a bearing and is rotatably driven in the counterclockwise direction as indicated by the arrow. Developer holding member 1
2 is not limited to a cylindrical body (sleeve), but may be in the form of an endless belt that is rotatably driven. The developing sleeve 12
The exposed surface outside the container faces the surface of a latent image carrier 11, such as a photoreceptor, which is driven to move in the direction of arrow a, with a small gap therebetween.

Reference numeral 13 denotes a fixed permanent magnet (magnet) as a fixed magnetic field generating means that is inserted into the developing sleeve 12 and held in the position and orientation shown in the figure. This magnet 13 has a north pole 17 and a south pole 18.

The magnet 13 may be an electromagnet instead of a permanent magnet.

Reference numeral 23 has a base fixed to the side wall of the container at the -1-edge side of the opening of the developer supply container in which the developing sleeve 12 is disposed, and the tip end is opened by protruding into the inside of the container 14 from the two edges. ”
- A magnetic band 1/- as a magnetic particle restraining member disposed along the length of the edge, for example, made by bending an iron plate into a crosswise simplified shape.

FIG. 2 is a diagram showing the attitude and angle relationship of the magnetic blade 23 with respect to the developing sleeve 12. 19 is a point on the sleeve defined between the two sides of the container in which n sleeves 12 are arranged, "in the direction of sleeve rotation than the upper edge position of 1", on the downstream side of the magnetic pole 12 in the direction of sleeve rotation; center line of the blade,
n is the normal to the sleeve 12 at the point 19. The magnetic blade 23 has its distal end located at a point 19 with a gap d between the sleeve 12 and the center edge of the blade relative to the normal n to the sleeve 12 at the point 19. The sleeve is disposed toward the lower wave side in the direction of movement of the sleeve, with an angle δ formed between the sleeve and the sleeve. 0 is the angle 1■ formed by the vertical line m passing through the rotation center of the sleeve 12 and the normal line n, P is the line connecting the rotation center of the sleeve 12 and the center of the magnetic pole 17, and π is the chain line P and the vertical line m (position angle of the magnetic pole 17).

The gap distance d between the tip of the magnetic blade 23 and the surface of the developing sleeve 12 at the point 19 is 100 to 1000.
p, preferably 200 to 500 rivers, in this example 3
It is 00p. If this distance d is smaller than toou, there is a drawback that magnetic particles, which will be described later, become clogged and are pushed out to the outside of the blade. If it is larger than 1000 #L, a large amount of non-magnetic developer (described later) will leak out due to vibration, making it impossible to form a thin layer.

Reference numeral 27 denotes a magnetic particle circulation area limiting member whose lower surface is in contact with the upper surface of the magnetic blade 23 and whose front end surface 27a is an undercut surface.

20 and 24 are magnetic particles and non-magnetic developer contained in the developer supply container 14.

The bottom plate of the developer supply container 14 is extended below the developing sleeve 12, which is a developer holding member, to prevent the developer from leaking to the outside. In order to further ensure the prevention of leakage of the developer to the outside, the base is fixed to the leading edge of the extended bottom plate along the edge length 'F, and the leading edge is brought into light contact with the lower surface of the developing sleeve 12 to seal it. A member 21 is provided, and the gap 11 between the tip edge of the bottom plate extension 14b and the lower surface of the sleeve 12 is closed by the seal member 21.

The magnetic particles 20 have a particle size of 30 to 20011. , preferably 70 to 150 舊. Each magnetic particle may consist only of magnetic particles, may be a combination of a magnetic material and a non-magnetic phase, or may be a 7h-compound of two or more types of magnetic particles.

The magnetic particles 20 are distributed in the sleeve surface area facing the inside of the developer supply container 14, that is, between the containers in which the sleeve 12 is disposed, from the lower edge 14a to the magnetic particle restraining portion J. The non-magnetic developer 24 is attracted to each part of the sleeve surface area up to the tip of the blade 23 by the magnetic field of the magnet 13 in the sleeve 12, and covers the entire sleeve surface area as a magnetic attraction layer.
A large number of particles are stored on the outside of the magnetic adsorption layer for No. 2. Magnetic particles 20 and non-magnetic developer 2 into container 14
In step 4, the magnetic particles 20 are first introduced and held by adsorption as a magnetic adsorption layer on the sleeve surface area, and then the non-magnetic developer 24 is introduced. The magnetic particles 20 initially introduced are originally about 2 to 70% of the magnetic particles.
(weight) of non-magnetic developer, but it is also possible to include only magnetic particles. Furthermore, once the magnetic particles 20 are adsorbed and held on the sleeve surface area as a magnetic adsorption layer, they will not substantially shift to one side even if the device is vibrated or the device is tilted considerably, and the sleeve surface area will be completely covered. The covered state is maintained.

When the magnetic particles 20 and the non-magnetic developer 24 are placed in the container 14 as described above, the magnetic particle magnetic adsorption layer in the vicinity of the sleeve surface corresponding to the magnetic pole 17 position of the magnet 13 is The strong magnetic field of the magnetic pole 17 forms a magnetic brush 20a of magnetic particles.

In addition, the magnetic particle magnetic adsorption layer near the tip of the magnetic blade 23, which is a magnetic particle restraining member, is rotated by the sleeve 12 in the direction indicated by the arrow, so that the force of gravity, magnetic force, and magnetic blade 2
Due to the balance between the restraining force based on the effect of the presence of 3 and the conveyance force in the moving direction of the sleeve 12, the sleeve 12 is restrained at the point 19 on the surface, and although it moves somewhat, it hardly moves 1b. 20b is formed.

Also, when the sleeve 12 is rotated in the direction of arrow l), the magnetic pole 1
By appropriately selecting the arrangement position of the magnetic particles 7 and the iM, dynamics, and magnetic properties of the magnetic particles 20, the magnetic brush 20a circulates in the direction of the arrow C in the vicinity of the magnetic pole 17, forming a circulating layer 20c. In the circulation layer 20c, the relatively small magnetic particles are attached to the sleeve 12 by the rotation of the sleeve 12.
The stationary layer 2 located on the rotationally downstream side of the sleeve from the vicinity of 7
It rises above 0b. In other words, the two parts receive a pushing force. The pushed-out magnetic particles are transferred to a magnetic particle circulation area limiting member 2 provided on the upper part of the magnetic blade 23.
Since the -1- limit of the circulation area is determined by 7, the magnetic blade 23-1 does not climb onto the magnetic blade 23-1-, but falls due to gravity and returns to 11 and the vicinity of the magnetic pole 17. In this case, magnetic particles that are located far from the sleeve surface and receive a small push-up force may fall before reaching the magnetic particle circulation area limiting member 27. That is, in the circulation layer 20c, the magnetic brush 20a of magnetic particles is circulated as shown by the arrow C due to the magnetic force and frictional force due to gravity and magnetic poles, and the fluidity (viscosity) of the magnetic particles. The non-magnetic developer 24 is sequentially taken in from the developer layer above the particle layer and returned to the lower part of the developer supply container 14, and this circulation is repeated as the sleeve 12 is rotated. The magnetic blade 23 does not directly participate in this circulation.

The non-magnetic developer that is sequentially taken in and mixed into the magnetic particle magnetic adsorption layer on the sleeve 12 side causes friction with the magnetic particles due to settling of the magnetic particles, friction between the non-magnetic developer particles, and friction with the surface of the developing sleeve. etc. to be charged. In this case, it is preferable to apply an insulating treatment such as an oxide film or a resin that is electrostatically at the same level as the non-magnetic developer to the surface of the magnetic particles to reduce the amount of tripo imparted by the magnetic particles and transfer the necessary charge to the developing sleeve 12. By doing so, it is possible to prevent the influence of deterioration of the magnetic particles, and the application of the developer to the developing sleeve 12 is stabilized.

Since the charged developer is non-magnetic, it is restrained by the magnetic field of the magnetic pole 17 while the sleeve surface rotates from the lower edge 14a of the container space 11 in which the sleeve 12 is disposed to the tip of the magnetic blade 23. , each part of the sleeve surface is coated uniformly and thinly by the reflection force.

Even if the magnetic particles 1; 1 sleeve 12 of the magnetic particle stationary layer 20b near the tip of the magnetic blade 23 is rotating, there is a constraint due to the effects of gravity, magnetic force, and the presence of the magnetic blade 23, as described above. It passes through the gap d between the tip of the magnetic blade 23 and the sleeve 12, being restrained by the balance between the force and the conveying force in the direction of movement of the sleeve 12.
As the sleeve 12 rotates, only the thin coating layer of the non-magnetic developer formed on the surface of the sleeve 12 passes through the gap d and rotates toward the support holder ll, and is applied to the surface of the latent image holder. Face to face up close. Reference numeral 24a indicates a thin coating layer of non-magnetic developer formed on the surface of the developing sleeve 12. Further, a portion where the developing sleeve 12 and the latent image holder 11, on which a thin layer of non-magnetic developer is formed, come close to each other is referred to as a developing section 30.

In the developing section 30, the non-magnetic developer layer 24a on the side of the developing sleeve 12 is heated by the electric field of the developing bias applied between the latent image holding body 11 and the developing sleeve 12 by the bias power supply 25. The latent images are selectively transferred and deposited in accordance with the latent image pattern, and the latent images are sequentially developed 24b (see, for example, Japanese Patent Publication No. 58-32375 for this developing method), and the bias power source 25 may be either alternating current or direct current. However, one in which direct current is superimposed on alternating current is preferable.

The surface of the developing sleeve that has passed through the developing section 30 and been consumed by selective development of the developer layer returns to the developer supply container 14 by the subsequent rotational drive of the sleeve, where it is once again formed into a magnetic particle magnetic adsorption layer. The cycle of contacting and being coated with the non-magnetic developer contained in the layer is repeated, and the surface of the latent image carrier 11 is continuously developed. As described above, the magnetic particle magnetic adsorption layer is provided with the magnetic particle circulation layer 2.
Due to the 0C, developer is sequentially taken in from the storage layer of non-magnetic developer 24 existing outside of the 0C, and is naturally replenished. Incidentally, in order to prevent the ghost image phenomenon, the developer layer that has not been subjected to development is removed from the surface of the developing sleeve that has returned to the container 14 and rotated, using a scraper means (not shown).
It is also preferable to scrape off the developer layer and bring the sleeve surface from which the developer layer has been scraped off to contact the magnetic particle magnetic adsorption layer to coat the developer.

The non-magnetic developer 24 includes 1, silica particles to improve the BI properties, and abrasive particles to polish the surface of the photoreceptor, which is the latent image carrier 11, in a transfer image forming system, for example. J: No, even if I add it externally. Alternatively, a non-magnetic developer 24 containing a small amount of magnetic particles may be used.

The supply of the magnetic particles 20 and the non-magnetic developer 24 into the developer supply container 14 is not limited to the method described above in which the magnetic particles 20 and the non-magnetic developer 24 are supplied in two stages. A substantially uniform mixture of magnetic particles and non-magnetic developer for the entire amount of the developer layer 24 is supplied in advance, and then the developer supply container 14 is vibrated or the developer holding member 12 is preliminarily moved. It may be rotated to separate and form two layers, a magnetic adsorption layer of magnetic particles on the sleeve surface and a non-magnetic developer layer 24 outside thereof, due to the difference in specific gravity between the magnetic particles and the non-magnetic developer and the magnetic field of the magnet 13.

Even if a substantially uniform mixture of magnetic particles and non-magnetic developer is supplied in advance, it is still possible to carry out the process as long as the amount of magnetic particles is sufficient to form a magnetic adsorption layer on the sleeve surface. be. However, in order to maintain long-term stability of the magnetic particle magnetic adsorption layer, it is preferable to first supply the magnetic particles 20 and then a non-magnetic developer into the container 14 to form the two layers.

In the case of a two-layer structure, the magnetic particle layer consisting of a stationary layer and a circulating layer is formed near the outer surface of the developer holding member 12 from the beginning, and the developer layer 24 does not contain any magnetic particles or Since the amount is small, the state of the magnetic particle layer 5 remains almost constant and does not change even if cartwheeling is continued for a long period of time. In this sense,
The magnetic particles in the magnetic particle layer are part of the developer rather than IIJ It l'll+ or part thereof.

A27 is a magnetic particle circulation castle restricting portion disposed in a part of the magnetic blade 23 which is a magnetic particle restricting portion l] A27 is a magnetic particle circulation castle restricting portion disposed in a part of the magnetic blade 23 which is a magnetic particle restricting portion l] It also prevents the leakage of magnetic particles, eliminates the swelling of magnetic particles onto the magnetic blade, and stabilizes the circulation of magnetic particles by preventing the reduction of the magnetic particles Bl in the developer tJj container and heating container due to unnecessary circulation. As a result, a thin layer of developer can be stably formed over a long period of time on the surface of the developer holding member.

3 and 4 show modified examples of the magnetic particle circulation castle limiting member 27, respectively.

In the example shown in FIG. 3, the tip side of the magnetic particle circulation area limiting member 27 protrudes inward from the container 14 of the example shown in FIG. This makes the magnetic particle circulation area narrower than in the example shown in FIG. As a result, the amount of magnetic particles 6 is effectively increased, and the ability to provide triboelectric particles is increased. In addition, the magnetic pole 1 of the magnetic particle circulation layer 20a that circulates the fastest
The pressure (gravity) of the upper developer on the magnetic particle area near 7
is now added directly.

It is possible to always obtain a stable magnetic particle circulation state.

In the example shown in FIG. 4, a magnetic particle circulation area limiting member 27 is disposed above a magnetic blade 23, which is a magnetic particle restraining member, with a gap 28 provided therebetween. In this case, the magnetic particle stationary layer 2
0b, as described above, does not move much even when the developer holding member 12 is rotated, so the magnetic particles in the magnetic particle circulation layer 20c enter the gap 28 and the effective amount of magnetic particles decreases. On the contrary, since the magnetic blade 23 and the member 27 are not in contact with each other, it is easy to set the gap distance d between the developing sleeve 12 and the magnetic blade 23, and the assembly is easy. Further, in this example, the developer supply device 14 and the member 2
7 can be integrated, which is advantageous in terms of strength and reduces cost.

Development execution example In the example device shown in FIG. 1, as the developer Ct holding portion 4112
A No. 20 aluminum sleeve whose surface was subjected to irregular sandblasting with 7 random abrasive grains was used. Incidentally, the surface may be roughened by blasting, regular blasting using glass or glass beads, etching, extrusion processing, sandpaper, anodic oxidation, or the like.

As the magnetic field generating means 13, a permanent magnet with two poles magnetized and having an N pole and an S pole as shown in FIG.
Figure 2) was used at 90°. The maximum value of the surface magnetic flux density of the magnet 13 is about 500 Gauss. In addition, it is preferable to further increase this strength for the developer used, especially a developer with slightly poor fluidity. Visual observation shows that for Magnet I, which has a surface magnetic flux density of approximately 800 Gauss, the magnetic flux density in the direction C in Figure 1 The magnetic particle circulation was approximately doubled.

The magnetic blade 23 is a 1.2-H iron plate coated with chemical nickel. SPC steel plates, silicon steel plates, permalloy, etc., which are commonly used industrially, are desirable as materials for the iron plate, and these magnetic materials may be magnetized to strengthen the magnetic field in the tangential direction. In Figure 2, θ=35°, δ=85°,
d=2501L. δ-90°, that is, the tangential direction of the sleeve may be used, but if the mechanical precision is poor, the magnetic blade 23 may hit the sleeve 12 on its belly, and δ>
This tendency is even more pronounced at 9o0, which is not preferable in terms of restraining the magnetic particles.

Furthermore, a polyethylene terephthalate sheet (thickness 0.2 m+s) was attached as a sealing member 21 as shown in Fig. 81. Further, instead of the seal member 21, a magnetic seal made of a magnetic material may be used in order to prevent leakage of magnetic particles due to the magnetic field between the seal member 21 and the magnetic pole 18.

The magnetic particles 20 have a particle size of 100 to 80 JL (150/
200 mesh) iron particles (maximum magnetization 1!30emu
/g), and as a non-magnetic developer 24, 0.8% nicoloidal silicate toner powder consisting of 5 parts of the same phthalocyanine pigment and having an average particle size of 1 oIL was externally added to 100 parts of the styrene/butane diene copolymer resin. I used a blue toner.

9 Then, when the developing sleeve 12 was rotated in the direction of arrow 1), the coating thickness was about 50~50 mm on the sleeve 121-.
A good non-magnetic developer coating layer 24a was obtained with a toner tripocharge h1 on the sleeve of +107 tc/g measured at 1100 IL and blow-off lJ:.

In addition, this developing device was installed in a Canon Co., Ltd. PC-10 type copying machine, and the bias weight (25) was set at a frequency of 1800.
Hz, peak-to-peak value + 300V AC voltage -3
When developing was carried out using a superimposed DC voltage of 00V and the distance between the sleeve 12 and the OPC photoreceptor 11 was set to 2501Lm, a bright blue image with good resolution was obtained. That's 1.

Although the non-magnetic developer 24 is used in this example, it has significantly weaker magnetism than the magnetic particles 20, and a magnetic developer can also be used as long as it can be tripo-charged. Furthermore, depending on the magnetic properties of the magnetic particles, the magnetic particle stationary layer 20b may not reach the blade 23 or 21, creating a portion where no magnetic particles exist between the stationary layer 20b and the blade 23. More toner may leak out. For this reason, it is desirable that the magnetic particles form a sufficiently long brush.

As described in detail above, according to the developing device of the present invention, the non-magnetic developer is coated stably over a long period of time by forming a uniform thin layer with sufficient charge on each part of the surface of the developer holding member. can be done. Therefore, this thin developer layer allows the latent image on the surface of the latent image carrier to be developed clearly and with good resolution.

In addition, magnetic developers can produce vivid colors, making it possible to produce high-quality color copies (single color, single color, etc.) with excellent color reproducibility.
Multicolor, natural color) can be obtained. Further, in the present invention,
Since the magnetic particle restraining member is tilted toward the downstream side in the direction of movement of the developer holding member, the magnetic field in the tangential direction can be stronger than the magnetic field in the normal direction on the developer holding member, and the magnetic particle circulation area limiting member Coupled with the stable circulation of the magnetic particles, blocking of the developer at the magnetic particle restraining member, fusion of the developer, and leakage of the magnetic particles can be prevented. Therefore, a pressure fixing toner can also be used as the developer.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view of the essential parts of an embodiment of the developing device of the present invention, FIG. 2 is an explanatory diagram of the arrangement position φ angle relationship of the magnetic blade with respect to the developing sleeve, and FIGS. 3 and 4 are modified examples, respectively. A cross-sectional side view of the main parts of. 11 is a latent image holding member, 12 is a developer holding member, 13 is a magnetic field generating means (magnet), 14 is a developer supply container, 23 is a magnetic particle restraining member, 27 is a magnetic particle circulation area limiting member, 20 is a magnetic particle , 20b and 20c are static layers and circulating layers of magnetic particles, and 24 is a non-magnetic developer.

Claims (1)

[Claims] (1) A developer tl (supply container) having an opening and containing non-magnetic developer and magnetic particles, and a developer holding member provided in the opening and capable of endlessly moving between the inside and outside of the container. , a magnetic particle restraining member that has a gap with the developer holding member on the row side of the developer holding member and is inclined toward the downstream side in the moving direction of the developer holding member; a fixed magnetic field generating means having a magnetic pole located inside the holding member on the upstream side in the moving direction of the developer holding member from a position facing the magnetic member; and magnetic particles disposed above the magnetic particle restraining member. A developing device comprising: a circulation area limiting member;