JPH0229671A - Method for forming thin layer of toner - Google Patents

Abstract

PURPOSE:To apply toner to a developer carrier so as to form a thin layer by providing a regulating member regulating the passage of carriers of developer in the upstream of the rubbing area of the periphery of a developer carrier. CONSTITUTION:After agitated and mixed by an agitating member 7, two- component containing developer is carried upward by a belt conveyer 3, falls down from a bucket near the upper part of a guide plate 6, and reaches the lateral periphery of a developing sleeve 1 while rubbing the guide plate 6. The carriers 4 further drop to the bottom of a hopper 8, and the mixing rate of the carriers 4 with the toner 5 becomes maximum in the upper part of the developing sleeve 1. The toner 5 and a part of the carriers 4, both of which are applied to the developing sleeve 1, are carried toward a blade 2 from the contact position together with the rotation of the developing sleeve 1. The blade 2 abutting on the periphery of the developing sleeve 1 scrapes away the carriers 4 and the toner 5 attaching to the developing sleeve 1 due to insufficient triboelectrification, and passes only a fixed amount of toner 5 sufficiently triboelectrified. Ultimately a uniform thin layer is formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is utilized in the field of development technology using a two-component developer having a toner and a carrier, and is particularly applicable to forming a thin layer of toner on a developer carrier. Regarding the method.

[Prior art and problems to be solved by the invention] As a developing method using a two-component developer of toner and carrier,
There is one disclosed in Japanese Unexamined Patent Publication No. 62-96956.

In this method, a blade that regulates the carrier is elastically brought into contact with a developing sleeve as a developer carrier in which a magnetic field generating means is installed, and a magnetic restraining force is applied by the magnetic field generating means to the vicinity of the blade. It is something that gives rise to a career cycle. The circulation of the carrier agitates the toner and ensures sufficient so-called tribo to apply the toner onto the developing sleeve.

However, sufficient space is required to circulate the carrier sufficiently, and the amount of carrier must be kept to a small amount, and the presence rate of carrier on the surface of the developing sleeve near the blade must be 10% or less. .

As a result, there is a problem in that the amount of toner transported by the carrier is insufficient, and a uniform thin layer of toner is formed on the developing sleeve and cannot be transported to the developing area, resulting in so-called ghost development during development.

[Means for Solving the Problems] An object of the present invention is to solve the above-mentioned problems and provide a method for uniformly applying a thin layer of toner onto a developer carrier.

To achieve the above object, the present invention provides a two-component developer comprising a toner and a carrier that imparts an electric charge to the toner and has a particle size larger than the particle size of the toner, on the side of a rotating developer carrier. Contacting or rubbing against the circumferential surface of the part with a restraining force and conveying it upward while being supported on the circumferential surface,
At the upper position of the developer carrier, the binding force to the carrier is weakened, and the developer is separated from the surface of the carrier and circulated in the developer container. It is constructed by bringing into contact a regulating member that regulates the passage of the developer carrier at a position above the contact or sliding area, and causing the carrier to separate from the circumferential surface of the developer carrier by the regulating member.

[Embodiment] A device according to an embodiment of the invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing a developing device as an embodiment of the present invention. In the figure, l is a developing sleeve as a developer carrier rotatable in the B direction,
It is disposed protruding from the front opening of the hopper 8 that accommodates the two-component developer.

The second developer stored in this hopper 8 is toner 5.
and a non-magnetic carrier 4 having a diameter larger than the particle diameter of the toner. Further, a stirring member 7 is disposed at the bottom of the hopper 8 as a means for stirring the developer. Further, in the center of the interior of the hopper 8, the developer sufficiently stirred by the stirring means 7 is restrained and once conveyed upward, and then the side peripheral surface of the developing sleeve 2 is provided with a belt having a packet as a means for dropping the developer. A conveyor 3 is provided. A guide plate 6 is disposed from the developer fall start position of the belt conveyor 3 to a position near the circumferential surface of the developing sleeve 1.

Further, on the circumferential surface of the developing sleeve l at a position higher than the area of the circumferential surface of the developing sleeve l which is in contact with the developer falling by the belt conveyor 3 and at a downstream position in the rotational direction B of the developing sleeve l, there is a carrier for the developer. An elastic blade 2 as a regulating member is disposed in contact with the circumferential surface. FIG. 2 shows an enlarged view of the installation of the elastic blade 2. In the figure, the blade 2 is pressed against and in contact with the circumferential surface of the developing sleeve 1, so that it is deformed as shown. This forces the end of the plate 2 to come into contact with the sleeve l. Note that the blade end here refers to the blade tip, the vicinity including the tip, or the vicinity of the tip not including the tip.The blade 2 is of a so-called counter type that is inclined downstream from the end in the rotation direction B of the developing sleeve. ing. The dotted line indicates the state of the blade 2 assuming that the developing sleeve l does not exist. The straight line m is a vertical line passing through the center O of the developing sleeve 1, and the straight line n is a straight line passing through the contact portion Q between the blade 2 and the developing sleeve l and the center 0 of the developing sleeve l. Also, let X be the angle formed by straight line m and straight line n. At this time, the direction toward the upstream side with respect to the rotational direction B of the developing sleeve is defined as the ball, using the straight line m as a reference. In the figure, surface T is the bottom surface of the blade 2 in an undeformed state before it comes into contact with the developing sleeve l. Point P is the cross section of the line of intersection between plane T and the surface of developing sleeve l, angle θ is the angle between the tangent to developing sleeve l passing through point P and plane T, and the distance g
Id is the length by which the surface T enters the inside of the developing sleeve l. Here, the straight line m must pass through the point P. This is not necessarily necessary.The angle θ is set so that the blade 2 does not warp due to the friction force with the developing sleeve l when it rotates. 40″ from θ° preferably 2″ to 20′
is within the range of

Further, the amount of penetration d of the blade 2 is preferably 0.5 to 2 mm, and the edge portion of the tip of the blade 2 is preferably in the developing sleeve l.
It is preferable that it be in contact with. This is because if the edge of the tip of the blade 2 is away from the surface of the developing sleeve 1, there will be a problem that the carrier 4 will leak out from this gap.

Furthermore, regarding the above angle X, the following condition O''≦X≦90°
If X<O, which is preferably satisfied, a force acts in the direction of the blade 2, so the carrier 4 moves toward the blade 2.
It has been found that the particles tend to stay near the tip and hinder good circulation of the carrier 4. A more preferable range of angle X is 5''<x<40° due to gravity.

Note that it is preferable that the surface of the developing sleeve l has minute irregularities rather than a mirror surface from the viewpoint of uniformly applying toner.

For example, the material of the blade 2 has a JIS hardness of 40 to 8.
0'' rubber, preferably 50 to 70'', is good for stable formation of a thin developer layer. The thickness of the blade 2 is set to 0.5 to 3, because a certain amount of stiffness is required to prevent the carrier 4 from passing through the blade, and conversely, if the stiffness is too strong, the applied toner will be scraped off. .0
mm, preferably 1.0 to 2.0 mm.

Next, a two-component developer comprising carrier 4 and toner 5 of this embodiment will be explained.

In this example, the developer is a non-magnetic carrier 4 with a particle size of 4.
Glass beads or resin particles having a particle size of 0 to 200 µm can be used as the toner 5, and particles having a particle size of 1 to 20 µm can be used. Due to the relationship with the above carrier, as shown in Figure 3,
Only the carrier 4 with a large particle size is regulated by the blade 2, and the toner 5 is placed on the imaging sleeve 1.
It becomes possible to form a uniform thin layer of only a single layer.

The resin particles that can be used here are selected depending on the triboelectrification series with the toner, and generally include styrene resins, acrylic resins, rosin-modified resins, polyamide resins, fluorine resins, and the like.

According to the above-described specific embodiments, glass or
The two-component developer, which is a mixture of carrier 4, which is non-magnetic particles such as resin, and toner 5, is sufficiently stirred and mixed by the action of a stirring member 7, and then transported upward by a belt conveyor 3. It is transported and dropped from the bulkhead near the top of the guide plate 6. This falling developer reaches the side peripheral surface of the developing sleeve l while rubbing against the guide plate 6. Here, after the carrier 4 coats the toner 5 onto the developing sleeve l, most of it further falls to the bottom of the hopper 8, so the mixing ratio of the toner 5 to the carrier 4 (Cp ratio) is the same as that of the developing sleeve 1. It becomes large at the top. Further, as the developing sleeve 1 rotates, the toner 5 and part of the carrier 4 coated on the developing sleeve 1 are transported from the contact position toward the blade 2. Here, the blade 2 that is in contact with the circumferential surface of the developing sleeve removes some of the developer that has been conveyed.
Toner 5 adhering to the developing sleeve 1 due to insufficient triboelectricity and carrier 4 is scraped off, and only a certain amount of toner 5 to which triboelectricity is sufficiently applied is allowed to pass through to form a uniform thin layer.

Next, another actual flow side that realizes the present invention will be explained based on FIG. In the apparatus of this embodiment, a two-pole magnet 19 is disposed as a magnetic field generating means inside the developing sleeve 11, and unlike the previous embodiment, a thin layer of toner 15 is generated using a magnetic carrier 14. It is something that forms.

In the figure, a developing sleeve 11, which is a rotatable portion rotating in direction B, is disposed with a portion protruding from the front opening of a hopper 18 that stores two-component developer. A magnet 19 as a magnetic field generating means is disposed inside the developing sleeve 11, and the magnet has bimagnetism of north and south poles.

The two magnetic poles with the S pole are arranged at the bottom of the developing sleeve,
It is arranged near the hopper 18 at the north pole or the intermediate position.

The two-component developer stored in the hopper 18 is a mixture of toner 15 and magnetic carrier 14 at a constant ratio, and the particle size of the carrier 14 is larger than that of the toner 15 as in the previous embodiment. It is said that In addition, the above-mentioned developing sleeve 1
A blade 12 made of a non-magnetic and elastic member is in contact with the circumferential surface near the top of the blade 1 .

In this embodiment, the magnetic force of the magnet 19 is applied to the carrier 14 at the lower part of the developing sleeve 11, but the binding force is weakened toward the upper part of the developing sleeve 11, so that the carrier 14 can easily fall by itself. It forms a special circulation as indicated by the arrow in Fig. 4, and T/
The C ratio is set to be large on the upper circumferential surface of the developing sleeve and small on the lower circumferential surface.

The characteristic configuration of this embodiment will be explained below. First, when the position where the blade 12 contacts the developing sleeve 11 is designated as D, the relationship with the above-mentioned magnetic pole N of the magnet 19 that is close to the blade 12 will be explained.

Set the center of rotation of the developing sleeve 11 to 0. It has been experimentally confirmed that if E is the position of the magnetic pole N, δ, which is the angle DOE, is required to be 300 or more. When δ is 30 degrees or less, the magnetic force of the magnetic pole N is applied at the contact position of the blade 12 and the carrier 14
A restraining force acts on the carrier 14, causing poor circulation of the carrier 14, and making it difficult to prevent the carrier 12 from leaking at the blade contact position.

Next, the setting method and material of the blade 12 will be explained. The blade 12 may be brought into pressure contact with the developing sleeve 11 at the edge angle of its tip, or may be brought into pressure contact with the developing sleeve 11 at its belly surface. Carrier 14 rises above the surface.
It is preferable to set the edge angle at the same time so that the nip in contact with the nip is widened because it leaks through the contact portion [D] and has a negative effect on the image quality. Further, in the setting form of the blade 12, the blade 12 (2) in the rotational direction B of the developing sleeve 11 is similar to that shown in FIG.
Is it possible to use either a counter-type pressure welding in which the gap between the developing sleeve 11(1) and the circumferential surface of the developing sleeve 11(1) gradually increases, or a forward-type pressure welding in which the gap gradually decreases?
In the case of forward pressure contact, the carrier 14 and toner 15 may accumulate in the gap between the blade 12 and the developing sleeve 11, and it is preferable to use a counter type blade to prevent the carrier 14 from easily leaking. The material of the blade 12 is preferably selected from a material that is used as a regulating member for the carrier 14 and which imparts the expected charge polarity to the toner 15 through friction when it comes into contact with the toner 15. Although it depends on the material, for example, ethylene propylene, fluorine rubber, natural rubber, polychlorobutadiene, N, B, R, etc. are effective in order to positively charge a toner whose main component is polystyrene. Silicone rubber, polyurethane, styrene-butadiene rubber, etc. are effective for charging.

The hardness of the rubber described above is preferably 50 to 706 according to JIS. If it is over 70", the elasticity of the rubber will become strong and the pressure on the contact surface will become too high, making the toner layer too thin and sufficient image density cannot be obtained. On the other hand, if it is less than 50", the elasticity of the rubber itself will become too high. This weakens the body and makes it difficult to apply sufficient pressure at the blade contact area.

The two-component developer used in the apparatus of this embodiment will be explained below.

As the magnetic carrier 14 used in this embodiment, conventionally known ferromagnetic or paramagnetic particles can be used, such as metal particles of iron, chromium, nickel, cobalt, triiron tetroxide, gamma oxide, etc. diiron, chromium dioxide, manganese oxide,
Metal oxides such as ferrite, alloys such as manganese and copper-based alloys, and resin carriers in which the above magnetic particles are dispersed in resin materials can be used. Further, since the carrier 14 is not applied to the surface of the developing sleeve 11, it is possible to use both the conductive carrier 6 and the insulating carrier.

Regarding the particle size of the carrier 14 and toner 15, in order to reliably control the carrier 14 by the blade 12 described above, the particle size of the toner 15 is 1 to 20g+i, and the carrier 14
The particle size ranges from 40 to 100 JLts. 40J
Below Lm, it becomes difficult for the blade 12 to regulate the carrier, and on the other hand, when it is above 100 JJ, +1, the toner 7 retention ability is significantly reduced.

Since the carrier 14 transports the toner 15 and provides triboelectricity, the amount of the carrier 14 and the mixing ratio of the toner 15 greatly influence the amount of toner transported on the developing sleeve 1. A practical investigation on this point revealed that the amount sufficient to form the above-mentioned circulation C by the carrier 14 was within the range of 1.0 to 5.0 g/cm per unit length of the circumferential surface of the sleeve 2. .

Also, the mixing ratio of toner 15 and carrier 14 (T/C ratio)
Therefore, it is only necessary to ensure a minimum amount of toner 15 that can be sufficiently supplied to the developing sleeve 11. In experiments conducted by the inventor of the present application, a sufficient coating amount was obtained within the range of T/C ratio from 6 to 40 wt%. If it is less than 6%, the coating amount will be insufficient, and if it is more than 40%, the circulation of the carrier 14 will be insufficient due to the toner 15, the opportunity for contact between the toner 15 and the carrier 14 will decrease, and the triboelectricity of the toner 15 will be insufficient or the transportation of the toner 15 will be insufficient. This results in problems such as insufficient performance.

As described above, since the T/C ratio can be set within a wide range in the apparatus of this embodiment, there is no need for a toner density control mechanism generally used in two-component development.

S, the point that this T/C ratio can be set widely is the same in the above-mentioned embodiments. Further, since a sufficient amount of toner 15 is always supplied to the developing sleeve 11 under the setting of the T/C ratio, the toner 15 has sufficient triboelectricity without causing a ghost phenomenon unlike the conventional apparatus. Furthermore, since the carrier 14 constantly rubs against the peripheral surface of the developing sleeve 11, the toner 15 is replaced, and abnormal charge-up does not occur in areas where toner consumption is low. According to the apparatus of this embodiment having the configuration described in detail above, as the developing sleeve 11 rotates, the carrier 14 carried on the circumferential surface of the developing sleeve 11 and the vicinity transfers the attached toner 15 to the developing sleeve 11.
It is conveyed at the same time as it is applied to the circumferential surface, but as it approaches the blade 12, the magnetic binding force is weakened and its amount is reduced. Thereafter, the carrier 14 is reliably peeled off from the circumferential surface of the developing sleeve 11 by the blade 12, and a uniform thin layer of toner is applied onto the circumferential surface of the developing sleeve 11.

The carrier 14 that has naturally fallen or been peeled off in this way falls toward the bottom of the hopper 18 due to the action of gravity, forming a large circulation path as shown by arrow C in FIG. The /C ratio will be large and small at the bottom. Due to this circulation of the carrier 14, the toner 15 is constantly supplied and replaced.
It becomes possible to ensure an appropriate amount of toner 15 and triboelectricity, and uniformly apply a thin layer onto the developing sleeve 11.

[Effects of the Invention] According to the method of the present invention as explained above, the toner and carrier are sufficiently stirred and then transported on the developer carrier, and the developer regulating member is in contact with the upper peripheral surface of the developer carrier. Since a sufficient amount of toner can be secured in the vicinity of , it is possible to form a uniform thin layer of toner with sufficient triboelectricity.

In addition, the restraining force of the carrier is weakened at the upper part of the developer carrier, and the carrier is in a state where it easily falls, so the amount of carrier decreases as it moves upward, and as a result, the carrier is reliably regulated by the regulating member. There is no problem of the carrier passing through.

Furthermore, since the setting range of the mixture ratio of toner and carrier can be increased, there is no need to provide means for controlling the mixture ratio as in conventional devices.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of an apparatus embodying the present invention, FIG. 2 is an enlarged view showing the vicinity of the blade of the apparatus, and FIG. FIG. 4 is a diagram illustrating another embodiment of the present invention. 5;15......Toner 4;14...Carrier

Claims (7)

[Claims] (1) A two-component developer comprising a toner and a carrier that imparts an electric charge to the toner and has a particle size larger than the particle size is brought into contact with the side peripheral surface of the rotating developer carrier with a restraining force. Alternatively, the developer is rubbed and transported upward while being supported on the peripheral surface, and at the upper position of the developer carrier, the binding force to the carrier is weakened to cause the developer to separate from the surface of the carrier and fall. A regulating member for regulating the passage of the developer carrier is brought into contact with a position above the contact or rubbing area on the circumferential surface of the developer carrier, and the regulating member causes the carrier to develop. A method of forming a thin layer of toner by separating the toner from the peripheral surface of the agent carrier. (2) The regulating member is an elastic blade whose tip is oriented in a direction opposite to the rotating direction of the developer carrier. How to form. (3) The method for forming a thin layer of toner according to claim (1), wherein the carrier is a non-magnetic particle. (4) The method for forming a thin layer of toner according to claim (3), wherein the non-magnetic carrier is glass beads or resin particles with a particle size of 40 to 200 micrometers. (5) The method for forming a thin toner layer according to claim (2), wherein the carrier regulated by the elastic blade is a magnetic particle. (6) The method for forming a thin toner layer according to claim 5, wherein the magnetic particle carrier has a particle size of 40 to 200 micrometers and contains at least conductive particles. (7) A method for forming a thin layer of toner according to claim 4 or claim 6, wherein the toner mixed with the carrier has a particle size of 1 to 20 micrometers.