JPH0883000A - Developing device - Google Patents

Abstract

PURPOSE: To reduce the irregularity of a toner image formed on an image carrier and the adhesion of carrier to the image carrier, to carry developer in a uniform thin layer state to a developing area by a developer carrying member and to obtain a uniform image having fine texture without image irregularity or the like at the time of developing by supplying the toner in the developer to the image carrier. CONSTITUTION: When the development is performed by carrying the developer to the developing area opposed to the image carrier and supplying the toner in the developer from the developer carrying member to the image carrier after a regulating member 13 regulates the quantity of the developer in the developer 1 including the toner T and the carrier C supplied on the developer carrying member 11, the carried quantity of the developer to the developing area by the developer carrying member is adjusted within the range of 0.7-5.0mg/cm<2> and also the developer whose correction bulk density is within the range of 0.28-0.37 and whose angle of repose is within the range of 38 deg.-52 deg. is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method for supplying a toner to a latent image formed on an image carrier to develop it in an image forming apparatus such as a copying machine or a printer.
A developer containing a toner and a carrier is supplied onto a developer carrying member, the amount of the developer on the developer carrying member is regulated by a regulating member, and then the developer carrying member carries an image on the developer. The present invention relates to a developing method in which a developer is conveyed to a developing area facing the body, and the toner in the developer is supplied from the developer conveying member to the image carrier to perform development.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, various methods have been known as a developing method for supplying a toner to a latent image formed on an image carrier to develop the latent image. . As a typical example of such a developing method, a developer containing a toner and a carrier is supplied onto a developer carrying member such as a developing sleeve having a magnet roller provided therein. The developer supplied to the image carrier is conveyed to the image carrier side in the state of a magnetic brush, and the amount of the developer on the developer carrier member is regulated by a regulation member, and then the developer is guided to a developing area facing the image carrier, and this development is performed. In the area, the developer is brought into contact with the surface of the image carrier in the state of a magnetic brush, and the toner in the developer is supplied from the developer carrying member to the latent image portion of the image carrier to perform the development. The method was known.

However, when the developer is brought into contact with the image carrier in the state of the magnetic brush to develop the toner, the toner supplied onto the image carrier is placed on the developer carrying member and the magnetic brush is used. There is a problem that the toner image formed on the image carrier is disturbed by being scraped off by the image carrier, especially when multi-color development is performed by sequentially supplying toners of a plurality of colors to the image carrier. When the toner of the color previously supplied to the image carrier is developed by supplying the toner of the next color, the toner is scraped off by the contact with the magnetic brush and the image is disturbed, or There is a problem that toners of other colors are mixed with each other, and good multicolor development with accurate colors cannot be performed.

Therefore, conventionally, a carrier having a low magnetic force is used as the above-mentioned developer, and the brush of the magnetic brush to be brought into contact with the image bearing member is softened to disturb the toner image due to the contact of the magnetic brush. It was thought to suppress.

However, when a carrier of low magnetic force is used in this way, the restraining force of the carrier is weakened, so that the carrier easily separates from the developer transport member and adheres to the image carrier, and in particular, the ladder pattern is used as an input image. When developing a high frequency image or an image such as a Chinese character pattern having a large number of strokes, many carriers adhere to the image carrier. Then, when the carrier adheres to the image carrier in this way, the carrier is transferred to the transfer paper together with the toner image, and the formed image is dropped by the carrier,
Further, there is a problem that the image carrier is scratched by the attached carrier and streak-like noise or spot-like noise occurs in the formed image.

Further, in recent years, in order to prevent the toner image formed on the image carrier from being disturbed by the magnetic brush of the developer as described above, JP-A-61-3 is used.
As disclosed in JP-A-2858, JP-A-62-182760, etc., when the amount of the developer on the developer conveying member is regulated by the regulating member, the layer of the developer on the developer conveying member is thin. As described above, when the developer is carried by the developer carrying member to the developing area facing the image carrier, the developer on the developer carrying member is prevented from coming into contact with the image carrier, and in this state, A developing device has been developed in which an oscillating electric field is applied to the developing area to supply the toner in the developer from the developer conveying member to the image carrier to perform the development.

However, in the case where the developer layer on the developer conveying member is thinly regulated by the regulating member as described above,
As shown in FIG. 1, the developer 1 aggregates on the developer transport member 11, and a thin uniform layer of the developer 1 cannot be formed on the developer transport member 11. There is a variation in the amount of the developer 1 on 11, and in this state an oscillating electric field is applied to the developing area as described above,
When the toner in the developer is supplied to the image carrier to perform development,
There are still problems that density unevenness or the like occurs in the formed image, especially in a halftone image, a uniform image with fine texture cannot be obtained, and the carrier adheres to the image carrier.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a developer containing a toner and a carrier is supplied onto a developer carrying member,
After the amount of the developer on the developer transport member is regulated by the regulation member, the developer transport member transports the developer to the developing area facing the image carrier, and the developer transport member releases the developer. An object of the present invention is to solve various problems as described above in the case where the toner inside is supplied to the image carrier to perform development.

That is, according to the present invention, in developing as described above, the toner image formed on the image carrier is disturbed or the carrier adheres to the image carrier,
There is no chance that the formed image will come off due to the carrier, or the image carrier will be scratched by the adhered carrier, and streak-like noise or spot-like noise will not occur in the formed image. It is an object of the present invention to obtain a uniform image with fine texture without causing concentration of the developer conveyed to the developing area by the member and without density unevenness.

[0010]

According to the present invention, in order to solve the above problems, a developer containing a toner and a carrier is supplied onto a developer carrying member, and development on the developer carrying member is carried out. After the amount of the developer is regulated by the regulating member, the developer conveying member conveys the developer to the developing area facing the image carrier, and the toner in the developer is conveyed from the developer conveying member to the image carrier. In the developing method of supplying and developing, the amount of developer conveyed in the developer conveying member for conveying the developer to the developing area is 0.7 to 5.
In addition to adjusting the range to 0 mg / cm ² , the developer used has a corrected bulk specific gravity of 0.28 to 0.37 and a repose angle of 38 ° to 52 °. is there.

[0011] In the developing method according to the present invention, was to adjust the amount of the developer conveyed to the conveyance to the developing area by the developer conveying member in the range of 0.7~5.0mg / cm ^2, the developer If the carry amount is less than 0.7 mg / cm ^{2, the} amount of toner supplied to the image bearing member will be insufficient, and an image having a sufficient image density of 1.3 or more cannot be obtained. Transport amount of 5.0mg / c
When it is more than m ² , the layer thickness of the developer conveyed by the developer conveying member becomes large, and the toner is supplied when the toner in the developer is supplied to the image carrier in the developing area to perform the development. The charge remaining on the carrier after the transfer is poor, and a large amount of counter charge remains on the carrier, and the carrier easily adheres to the image carrier, and the amount of toner scattered without being supplied to the image carrier increases. Is.

In the developing method of the present invention, the corrected bulk specific gravity of the developer is 0.28 to
The reason why the range of 0.37 is used is
When a developer having a corrected bulk specific gravity value of greater than 0.37 is used, the developer is likely to aggregate, and as shown in FIG. 1, the developer 1 aggregates on the developer transport member 11. The unevenness of the developer 1 on the developer transport member 11 causes unevenness of density in the formed image, especially in a halftone image, which makes it impossible to obtain a uniform image with fine texture. This is because if a developer having a value smaller than 0.28 is used, the fluidity of the developer is extremely deteriorated and the toner in the developer cannot be sufficiently charged. Here, the corrected bulk specific gravity indicates the clogging of particles per unit volume, and is represented by the formula of corrected bulk specific gravity = bulk specific gravity / true specific gravity. Regarding the corrected bulk specific gravity of the developer in the present invention, JIS K The apparent density (bulk specific gravity) of the developer was measured by the method specified in 5101, and the apparent density (bulk specific gravity) of the developer thus measured was divided by the true specific gravity of the developer.

In the present invention, the developer whose repose angle is in the range of 38 ° to 52 ° is used because the developer has a repose angle of 3 °.
When the angle is smaller than 8 °, the force of the developer to be caught on each other is weak, and when the amount of the developer 1 on the developer transport member 11 is regulated by the regulation member 13 as shown in FIG. When the magnetic brush composed of No. 1 easily breaks from any position, resulting in uneven layer thickness of the developer 1 on the developer transport member 11, while the angle of repose of the developer used is greater than 52 ° In this case, the attraction force between the developers becomes too strong, and the magnetic brush made of the developer becomes difficult to cut. For example, as shown in FIG. When the amount of the developer 1 is regulated, a part of the magnetic brush composed of the developer 1 passes through without being cut by the regulation member 13 and the amount of the developer 1 on the developer transport member 11 increases. This is because a portion is generated and the layer thickness of the developer 1 on the developer transport member 11 becomes uneven as in the above case. The angle of repose of the developer in this invention is a value measured using a powder tester manufactured by Hosokawa Micron.

Here, in the developing method of the present invention, it is sufficient that the above requirements are satisfied, and the developer carried by the developer carrying member to the developing area is developed without being brought into contact with the image carrier. Alternatively, the development may be performed in contact with the image carrier. However, it is preferable to carry out the development without bringing the developer into contact with the image bearing member, because the disturbance of the toner image formed on the image bearing member due to contact with the developer can be further suppressed.

[0015]

In the developing method according to the present invention, the developer containing the toner and the carrier is conveyed by the developer conveying member to the developing area facing the image carrier, and in the developing area, the developer is conveyed from the developer conveying member. When the toner is supplied to the image bearing member for development, the amount of developer conveyed by the developer conveying member to the developing area is 0.7 to 5.0.
Since the amount of the developer is adjusted to be in the range of mg / cm ² , a sufficient amount of the developer to be used for the development can be conveyed to the developing area, and the toner in the developer is conveyed from the developer conveying member to the image carrier. When the toner is supplied to the developing device and developed, the toner does not run short and an image having sufficient image density can be obtained, and the layer thickness of the developer conveyed by the developer conveying member is thin. Therefore, when the toner in the developer is supplied to the image carrier, the charges remaining in the carrier flow to the developer carrying member side, the counter charge remaining in the carrier is reduced, and the charge to the image carrier is reduced. Adhesion of carriers is suppressed, and toner scattering during development is reduced.

Further, in the developing method of the present invention, since the developer having the corrected bulk specific gravity in the range of 0.28 to 0.37 is used as the developer, the fluidity of the developer is used. 4 does not deteriorate extremely, the toner in the developer can be sufficiently charged, and the developer is not partially aggregated on the developer transport member. As shown, the developer 1 is evenly dispersed on the developer transport member 11 to form a dense magnetic brush of the developer 1 having a fine texture, and even a halftone image has unevenness. It is possible to obtain an image with fine texture without the occurrence of.

Further, in the present invention, since the developer whose repose angle is in the range of 38 ° to 52 ° is used as described above, the force with which the developers are caught is too weak or too strong. As shown in FIG. 5, when the amount of the developer 1 on the developer conveying member 11 is regulated by the regulating member 13, the developer 1 on the developer conveying member 11 is uniform and uniform. The thin layer is formed, and unevenness in density or the like does not occur in the formed image.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The developing method according to the embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 6 shows an example of the developing device 10 used for carrying out the developing method according to the embodiment of the present invention.

Here, in the developing device 10 shown in FIG. 6, the developer 1 containing the toner T and the carrier is accommodated therein, and as the developer carrying member 11 for carrying the developer 1, A plurality of magnetic poles N ₁ , S ₁ , N ₂ , S
A cylindrical developing sleeve 11 having a magnet roller 11a having N ₂ , N ₃ provided on the inner peripheral side is used, and this developing sleeve 11 is provided with an appropriate distance Ds from the photoconductor 2 which is the image carrier 2 in the developing area. They are rotatably held so as to face each other.

The developing sleeve 11 is attached to the photosensitive member 2
In the developing region in which the developing sleeve 11 and the photoconductor 2 face each other, the developing sleeve 11 and the photoconductor 2 are rotated so as to move in the same direction.
Developer 1 accommodated in the developing device 10 in accordance with the rotation of the developer 1.
Is conveyed to the photoconductor 1 side in the state of a magnetic brush by the magnetic force of the magnet roller 11a.

A developing bias power source 12 is connected to the developing sleeve 11. The developing bias power source 12 applies an alternating voltage or a developing bias voltage in which a direct current voltage is superimposed on an alternating voltage to apply a developing bias voltage. An oscillating electric field is applied to.

Further, the developing sleeve 11 and the photoconductor 2 described above are used.
A regulating member 13 for regulating the amount of the developer 1 on the developing sleeve 11 is provided at a position facing the magnetic pole N ₁ of the magnet roller 11a on the upstream side in the conveying direction of the developer 1 with respect to the developing area where and are opposed to each other. The magnetic blade 13a is provided so as to be spaced apart from the developing sleeve 11 by a required distance,
The magnetic blade 13a regulates the amount of the developer 1 on the developing sleeve 11.

Here, when the amount of the developer 1 on the developing sleeve 11 is regulated by the magnetic blade 13a in this way, as shown in FIGS. 7A to 7C, the toner T and the carrier C are provided. When the magnetic brush of the developer 1 containing the toner passes the position of the magnetic blade 13a, the magnetic brush of the developer 1 is provided with the magnet roller 11a provided on the inner peripheral side of the developing sleeve 11 and the magnetic blade 13a. Respectively, the magnetic brush of the developer 1 is cut at an appropriate position and passes through the magnetic blade 13a, so that an appropriate amount of the developer 1 is exposed by the developing sleeve 11. It is conveyed to the developing area facing the body 2.

Further, the developing device 10 is provided with a toner accommodating portion 14 for accommodating the toner T in the upper part thereof, and the toner T in the developer 1 is supplied from the developing sleeve 11 to the photoconductor 2 to develop the toner. As a result, the developing device 1
When the toner concentration in the developer 1 in 0 falls, the toner replenishing roller 15 provided under the toner containing portion 14 is rotated to develop the toner T contained in the toner containing portion 14. The developer 1 in the apparatus 10 is replenished.

Then, using such a developing device 1,
In carrying out the developing method of the present invention, the developer 1 has a corrected bulk specific gravity of 0.28 to 0.3.
7. The one whose repose angle is in the range of 38 ° to 52 ° is used, and the amount of the developer 1 conveyed to the developing area facing the photoconductor 2 by the developing sleeve 11 rotating as described above is In regulating the magnetic blade 13a, the amount of the developer 1 conveyed by the developing sleeve 11 was adjusted to be in the range of 0.7 to 5.0 mg / cm ² . After that, the developer 1 regulated in this way is guided to the developing region facing the photoconductor 2 by the developing sleeve 11, and a developing bias voltage is applied from the developing bias power source 12 to apply an oscillating electric field to this developing region. Then, the toner T in the developer 1 conveyed by the developing sleeve 11 is supplied from the developing sleeve 11 to the latent image portion of the photoconductor 2 for developing.

Here, when the developer 1 as described above is used, the amount of the developer 1 carried by the developing sleeve 11 is regulated by the magnetic blade 13a, and the carrying amount of the developer 1 carried to the developing area is controlled. Even when adjusted to the range of 0.7 to 5.0 mg / cm ² , the developer 1 does not aggregate on the developing sleeve 11, and when the magnetic brush of the developer 1 is cut by the magnetic blade 13a. In addition, the cutting position is unlikely to change, and the developer 1 is now conveyed to the developing area in the form of a dense thin layer having a uniform and fine texture on the developing sleeve 11. When development is performed in this state, a high-resolution image having sufficient image density, density unevenness, and the like and a fine texture can be obtained, and the carrier adheres to the photoconductor 2. None,
There is no possibility that the formed image will be removed by the carrier, noise will not be generated in the formed image due to the damage on the photoconductor 2, and the toner T will be less likely to be scattered during the development. The image is not fogged and the inside of the apparatus is not contaminated by the scattered toner T.

Next, the type and the mixing amount of the carrier and the toner used in the developer are changed to produce a developer having various corrected bulk specific gravity and angle of repose, and these developers are used as described above. An experiment is conducted using the developing device 10 to clarify that it is preferable to use a developer that satisfies the conditions shown in the present invention.

In this experiment, as the toner used for the developer, a positively charged toner T1 having an average particle diameter of about 11 μm and a negatively charged toner T2 having an average particle diameter of about 8 μm. And two types of toner are used.

On the other hand, as shown in Table 1 below, the carrier is composed of binder type carriers C1 to C7 and C9, C10 in which the particle size and the amount of magnetic powder are changed, and a ferrite carrier C8. Types of carriers C1 to C
10 was used. The amount of the magnetic powder in the binder type carriers C1 to C7 and C9, C10 is shown with respect to 100 parts by weight of the resin.

[0031]

[Table 1]

Then, as shown in Table 2 below, a developer (toner concentration Tc (wt%) obtained by combining the positively charged toner T1 and the carriers C1 to C10 as shown in the same table ( 1) to (17) are adjusted, and the true specific gravity and the bulk specific gravity of each of the developers (1) to (17) are measured to obtain the corrected bulk specific gravity of the developers (1) to (17). The angle of repose was measured, and the results are shown in the table.

[0033]

[Table 2]

As a result, the developers (1), (2),
In the case of (5) and (6), the corrected bulk specific gravity is 0.28 to
0.37, the angle of repose was in the range of 38 ° to 52 °, which satisfied the conditions of the developer in the present invention, but the developer (3), (4), (7) to (17) Did not meet the requirements of this invention.

Then, each of the developers (1) to (17) described above is used in the developing device 10 and the distance between the developing sleeve 11 and the magnetic blade 13a is set to 0.2 mm. And adjust the amount of developer 1 conveyed to 1.80 to 4.24 mg / cm ² .
The developing sleeve 11 and the photoconductor 2 facing each other in the developing area.
And the peripheral speed of the photoconductor 2 is 120 mm.
mm / s, the peripheral speed of the developing sleeve 11 is 240 mm / s
The surface potential of the portion of the photoconductor 2 to which the toner is supplied is −440V and the surface potential of the portion to which the toner is not supplied is −210V, and the DC voltage of + 180V from the developing bias power source 12 and the peak A rectangular wave having a peak value Vp-p of 1.5 kv and a frequency of 2 kHz, d
The developing bias voltage in which the alternating voltage having the duty ratio (development: recovery) of 1: 3 is superimposed is applied to perform regular development, and the state of the developer 1 conveyed to the developing area by the developing sleeve 11 is checked. At the same time, the formed image was evaluated.

The state of the developer 1 conveyed to the developing area by the developing sleeve 11 is shown in FIG. 8 according to the corrected bulk specific gravity and the angle of repose.
Is plotted, and the case where the developer is conveyed in the state of a uniform thin layer is indicated by ●, and the case where the developer is conveyed in the state of unevenness is indicated by ◯. As a result, the corrected bulk specific gravity is 0.28-
0.37, the angle of repose is in the range of 38 ° to 52 °, and the developers (1), (2), which satisfy the conditions of the present invention,
When (5) and (6) are used, the developing sleeve 11
Although the layer of the developer 1 conveyed to the developing area was thinly and uniformly formed by the developer, the developers (3), (4), (7) to (17) which do not satisfy the conditions of the present invention. In the case of using, the developer 1 conveyed to the developing area by the developing sleeve 11 was aggregated, and the thickness of the layer of the developer 1 was uneven.

Regarding the evaluation of the formed image,
The formed image was examined for density unevenness and texture to make a comprehensive evaluation. Then, the density unevenness was visually evaluated on a five-level scale. When no density unevenness was observed at all, 5, when density unevenness was slightly present but was not a problem, and when density unevenness was present to some extent 3, the case where there is considerable density unevenness is expressed as 2, and the case where the density unevenness is severe is expressed as 1. Also, the texture is evaluated in 5 grades by visual inspection, and even with halftone images, there is no variation and the texture is very fine and good. The case is 5, the case where there is some variation but the texture is good is 4, the case where there is variation to some extent and the texture is slightly lowered 3, and the case where there is variation and the texture is considerably worse, the texture is very bad When it is not, it is expressed as 1, and the overall evaluation is performed in five grades from A to E. A is very good, B is good, and the image quality is deteriorated to some extent. The case C, considerably when the image quality drops D, and if the image quality is remarkably bad E
The results are shown in Table 3 below.

[0038]

[Table 3]

As a result, when the developers (1), (2), (5) and (6) satisfying the conditions of the developer of the present invention are used, the density unevenness in the formed image is small and the texture is small. When the developer (3), (4), (7) to (17) which does not satisfy the conditions of the developer in the present invention is used, while the detail is good and the comprehensive evaluation is B or more. In addition, the formed image had uneven density and the texture was poor, and the overall evaluation was C or less.

Next, as shown in Table 4 below, a developer whose toner concentration Tc (wt%) is as shown in the same table by combining the above-mentioned negatively charged toner T2 and carriers C1 to C7. (18) to (30) are adjusted, and the true specific gravity and bulk specific gravity of each of the developers (18) to (30) are measured to obtain the corrected bulk specific gravity of the developers (18) to (30). The angle of repose was measured, and the results are shown in the table.

[0041]

[Table 4]

As a result, the developers (18), (19),
For (22) and (23), the corrected bulk specific gravity is 0.28.
.About.0.37, and the angle of repose was in the range of 38.degree. To 52.degree., Which satisfied the condition of the developer in the present invention.
The developers (20), (21), (24) to (30) did not satisfy the conditions of the developer in the present invention.

Then, the above-mentioned developers (18) to (30) are used in the developing device 10, and the distance between the developing sleeve 11 and the magnetic blade 13a is set to 0.2 mm to reach the developing area by the developing sleeve 11. Of the developer 1 is adjusted to 2.32 to 4.26 mg / cm ² , and
The developing sleeve 11 and the photoconductor 2 facing each other in the developing area.
And the peripheral speed of the photoconductor 2 is 180 mm.
mm / s, the peripheral speed of the developing sleeve 11 is 324 mm / s
The surface potential of the portion of the photoconductor 2 to which the toner is supplied is −80 V and the surface potential of the portion to which the toner is not supplied is −280 V, and a DC voltage of −210 V from the developing bias power source 12 Peak peak value V
a rectangular wave with a pp of 1.25 kv and a frequency of 3 kHz, d
The developing bias voltage is applied by superimposing the AC voltage having a duty ratio (development: recovery) of 1: 1 to perform reversal development, and the state of the developer 1 conveyed to the development area by the development sleeve 11 is checked. At the same time, the formed image was evaluated.

The state of the developer 1 conveyed to the developing area by the developing sleeve 11 is shown in FIG. 8 as in the case of the developers (1) to (17) described above. Depending on the corner, each developer (18) to (30)
Is plotted, and the case where the developer is conveyed in the state of a uniform thin layer is indicated by ●, and the case where the developer is conveyed in the state of unevenness is indicated by ◯. As a result, the corrected bulk specific gravity is 0.28-
0.37, the angle of repose is in the range of 38 ° to 52 °, and the developers (18), (19), which satisfy the conditions of the present invention,
When (22) and (23) are used, the layer of the developer 1 conveyed to the developing area by the developing sleeve 11 is thin and uniform, whereas the developing condition which does not satisfy the conditions of the present invention is used. Agents (20), (21), (24) to (3
When 0) was used, the developer 1 conveyed to the developing area by the developing sleeve 11 was agglomerated, and the layer thickness of the developer 1 was uneven.

Regarding the evaluation of the formed image,
Evaluation was performed in the same manner as in the case of Table 3 above, and the results are shown in Table 5 below.

[0046]

[Table 5]

As a result, the developers (18), (19), (22), (2) satisfying the conditions of the developer in the present invention are obtained.
When 3) was used, the density unevenness in the formed image was small, the texture was fine, and the overall evaluation was good at B or higher. On the other hand, the development not satisfying the conditions of the developer in the present invention was performed. Agents (20), (21), (24)
In the case of using (30) to (30), unevenness in density was generated in the formed image and the texture was deteriorated, and the comprehensive evaluation was C or less.

Next, in the developing device 10, the influence when the amount of the developer 1 to be conveyed to the developing region by the developing sleeve 11 was changed was examined.

Here, as a carrier in the developer 1, 100 parts by weight of a styrene-acrylic resin and 2 parts of the magnetic powder 2 were used.
00 parts by weight, carbon black and silicon oxide are added,
Binder type carrier manufactured to have an average particle size of 20 μm, a true specific gravity of 2.4 and a magnetic force of 1050 G /
cm ³ and electric resistance of 1 × 10 ¹⁴ Ω · cm are used, and as the toner, styrene-acrylic resin is added with carbon black, wax and positive charge control agent (Nigrosine manufactured by Orient Chemical Industry Co., Ltd.). A positively-charged toner having an average particle size of about 11 μm, which was post-treated with silicon oxide, was used.

Then, by using the developer having the toner concentration of 20 wt% by mixing the carrier and the toner, the developer 1 conveyed to the developing area by the developing sleeve 11 in the developing device 10 is used. The carrying amount was adjusted by the magnetic blade 13a, and the carrying amount of the developer 1 was adjusted to 2.5 mg / cm ² and 30 mg / cm ² .

When developing using the developing device 10, the peripheral speed of the photoconductor 2 is set to 120 mm /
s, the peripheral speed of the developing sleeve 11 was adjusted to 240 mm / s, and the surface potential of the portion of the photoconductor 2 to which the toner was supplied was −440V and the surface potential of the portion to which the toner was not supplied was −210V.

Further, from the developing bias power source 12, a developing bias in which a DC voltage of -250 V and a DC voltage of -250 V are superimposed on each other is formed by a rectangular wave having a frequency of 2 KHz and a duty ratio (development: recovery) of 1: 1. Voltage is applied, and the peak-peak value Vp-p of the AC voltage is 0 to 3
The distance Ds between the developing sleeve 11 and the photoconductor 2 in the developing area is 0.3 to 0.6 m while adjusting in the range of KV.
The oscillating electric field (V
The strength of pp / Ds) was changed.

Then, as described above, the carrying amount of the developer 1 carried by the developing sleeve 11 to the developing area is 2.5.
mg / cm ² and 30 mg / cm ^2, and the strength of the oscillating electric field (Vp-p / Ds) acting on the developing area as described above is changed for each, and the strength of the oscillating electric field and the developing sleeve are adjusted. The relationship with the potential decrease rate of the developer layer on No. 11 was investigated, and the result is shown in FIG. Regarding the potential decrease rate of the developer layer, the toner in the developer 1 is supplied from the developing sleeve 11 to the photoconductor 2 and stopped during the development, and the developing layer 11 on which the toner is supplied is stopped. The potential of the developer layer was measured, and the potential of the developer layer when the development was performed without applying an AC voltage was set to 1 and represented by the ratio.

As a result, if the oscillating electric field (Vp-p / Ds) acting on the developing area is too weak, the potential decrease in the developer layer is small regardless of the amount of the developer 1 conveyed by the developing sleeve 11, and the toner is not discharged. The charge transfer in the carrier after developing by supplying the toner is poor, and a lot of counter charge remains in the carrier, and a large amount of the carrier adheres to the photoconductor 2. On the other hand, the strength of the oscillating electric field is 5.5 KV /
When the thickness was equal to or greater than mm, a leak occurred between the photosensitive member 2 and the photosensitive member 2.

On the other hand, when the strength of the oscillating electric field (Vp-p / Ds) is adjusted to the range of 3.5 to 5 KV / mm, the developer 1 is transported by the developing sleeve 11 in an amount of 0.7 to 5.0 mg.
/ If you 2.5 mg / cm ² in the range of cm ^2, taken reduction potential is greater in the developer layer, now the developer layer is almost completely ionized, and supplies toner The charges remaining on the carrier later quickly moved, the counter charge on the carrier was almost eliminated, and the adhesion of the carrier to the photoconductor 2 was suppressed. On the other hand, when the amount of developer 1 conveyed is 30 mg / cm ² , even if an oscillating electric field in the range of 3.5 to 5 KV / mm is applied, the potential of the developer layer is not significantly reduced and the toner is The charge remaining on the carrier after supplying was poor, and a large amount of counter charge remained on the carrier, and the carrier was often attached to the photoconductor 2.

Next, the toner concentration in the above-mentioned developer is adjusted within the range of 5 to 30 wt%, and the carrying amount of the developer 1 by the developing sleeve 11 in the above-mentioned developing device 10 is shown in Table 6 below. 2-30mg / cm ²
I changed it in the range of.

When developing with the developing device 10, the peripheral speed of the photoconductor 2 is 120 mm / s,
The peripheral speed of the developing sleeve 11 is adjusted within a range of 1 to 3 times the peripheral speed of the photoconductor 2, and the surface potential of the part of the photoconductor 2 to which the toner is supplied is -440V, and the surface potential of the part to which the toner is not supplied is The voltage is set to −210 V and the frequency from the developing bias power source 12 is 2 to 4 KHz, d.
The developing bias voltage was applied by superimposing the AC voltage composed of a rectangular wave with the duty ratio (development: recovery) in the range of 1: 1 to 1: 3 and the DC voltage of -400 to + 640V.

Then, the peak-peak value Vp-p of the AC voltage is adjusted in the range of 0.75 to 3 KV, and
The distance Ds between the developing sleeve 11 and the photoconductor 2 in the developing area is adjusted in the range of 0.3 to 0.6 mm, and the oscillating electric field (Vp-p / Ds) applied to the developing area is shown in Table 6 below.
As shown in (4), it was changed in the range of 2.5 to 5 KV / mm.

Then, as described above, the carrying amount of the developer 1 by the developing sleeve 11 and the oscillating electric field (Vp-p / Ds) acting on the developing area are changed as shown in Table 6, and the development is performed. Under each condition, the state of the carrier attached to the photoconductor 2 was examined, and the results are shown in the same table. In Table 6, the state of the carrier attached to the photoconductor 2 is visually evaluated on a scale of 5 to 5 when there is no carrier attachment, 4 when there is slight carrier attachment, and some degree of carrier attachment is confirmed. The case where it is possible is indicated by 3, the case where considerable carrier adhesion is confirmed is indicated by 2, and the case where carrier adhesion is large is indicated by 1. Further, when the oscillating electric field applied to the developing area was too strong and a leak was generated between the photosensitive body 2 and the photoconductor 2, it was indicated as a leak.

[0060]

[Table 6]

As is clear from this result, when the amount of the developer 1 conveyed by the developing sleeve 11 is 5 mg / cm ² or less, the oscillating electric field is 3.5 to 5.0 KV / mm.
When the development was carried out within the range of No. 2, no carrier adhesion to the photoconductor 2 occurred. On the other hand, the developing sleeve 1
When the carrying amount of the developer 1 by 1 is more than 5.0 mg / cm ² , the oscillating electric field is 3.5 to 5.0 KV / mm.
Even in the above range, the adhesion of the carrier to the photoconductor 2 was gradually increased, and the toner was scattered during the development.
When the oscillating electric field was set to 5.5 KV / mm or more, the electric field strength became too strong and a leak occurred between the developing sleeve 11 and the photoconductor 2.

Further, when the developer 1 is carried by the developing sleeve 11 at a carrying amount of less than 0.7 mg / cm ² , the toner is not sufficiently supplied to the photoconductor 2, An image having a sufficient image density could not be obtained.

In the above embodiment, only the example in which development is performed by the developing device 10 shown in FIG. 6 is shown, but the type of developing device used is not particularly limited to the above. Instead, for example, the developing device 10 shown in FIG.
As described above, the developer 1 in the developing device 10 is agitated by the agitating member 16, and the developer 1 thus agitated is supplied to the developing sleeve 11. Then, as a regulating member 13, a regulating plate is provided on the surface of the developing sleeve 11. 13b are brought into contact with each other, the amount of the developer 1 on the developing sleeve 11 is regulated by the regulating plate 13b, and the developer 1 returned into the developing device 10 after development is recovered by a roller 17.
Alternatively, the developing sleeve 11 may be scraped off from the surface thereof. Further, the method of adjusting the amount of the developer 1 to be conveyed to the developing area by the developing sleeve 11 by the regulating member 13 is not limited to the method of the developing device 10 shown in FIG. 6 and FIG. 10 described above. As shown in FIG. 11, it is also possible to provide a regulating rod 13c so as to face the developing sleeve 11 with a required gap, and regulate the amount of the developer 1 on the developing sleeve 11 by this regulating rod 13c. Note that, also in the case shown in FIG. 11, the developer 1 returned to the inside of the developing device 10 after development is scraped off from the surface of the developing sleeve 11 by the scraping plate 18.

[0064]

As described above in detail, in the developing method of the present invention, the developer containing the toner and the carrier is conveyed to the developing area facing the image carrier by the developer conveying member, and in this developing area, When the toner in the developer is supplied from the developer transport member to the image carrier to perform development,
Since the amount of the developer conveyed to the developing area by the developer conveying member is adjusted as described above, an image having a sufficient image density can be obtained, and carrier adhesion to the image carrier is suppressed, so that the formed image is formed. There is a dropout due to the carrier,
The image carrier is not scratched by the adhered carrier, and streak-like or spot-like noise is not generated in the formed image, and a good image can be stably obtained, and toner is scattered. I've run out.

Further, in the developing method of the present invention, since the developer having the corrected bulk specific gravity and the angle of repose within the above ranges is used as the developer, the developer is conveyed to the developing area by the developer conveying member. Even when the amount is adjusted as described above, the developer is not aggregated on the developer transport member and the layer thickness of the developer transported by the developer transport member is not uneven. , The developer is uniformly dispersed on the developer transport member, and a dense magnetic brush of the developer is formed, so that image unevenness occurs even in a halftone image. Instead, the texture is fine and high resolution images can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a state in which a developer aggregates on a developer transport member when a developer having a large corrected bulk specific gravity is used.

FIG. 2 shows a case where a developer having a small angle of repose is used, and when the amount of the developer on the developer transport member is regulated by the regulation member, the layer thickness of the developer on the developer transport member becomes uneven. It is a schematic explanatory drawing which showed the state.

FIG. 3 shows a case where a developer having a large angle of repose is used, and when the amount of the developer on the developer transport member is regulated by the regulating member, the layer thickness of the developer on the developer transport member becomes uneven. It is a schematic explanatory drawing which showed the state.

FIG. 4 is a schematic explanatory view showing a state in which the developer is uniformly dispersed on the developer transport member without agglomeration in the developing method of the present invention.

In the developing method of the present invention, when the amount of the developer on the developer transport member is regulated by the regulation member, a uniform and even thin layer of the developer is formed on the developer transport member. It is a schematic explanatory drawing which showed the state.

FIG. 6 is a schematic explanatory view showing an example of a developing device used for carrying out the developing method according to the embodiment of the present invention.

FIG. 7 is a partially enlarged explanatory view showing a state in which the amount of developer on the developing sleeve is regulated by a magnetic blade in the developing method of the embodiment.

FIG. 8: Developers (1) with different corrected bulk specific gravity and angle of repose
9 is a graph showing how the developer is conveyed on the developing sleeve when (30) is used and the amount of the developer on the developing sleeve is regulated by a magnetic blade. .

FIG. 9: The amount of developer conveyed by the developing sleeve is 30 mg.
² is a graph showing the potential reduction rate of the developer layer when the development is carried out by changing the strength of the oscillating electric field applied to the development area at / cm ² and 2.5 mg / cm ² .

FIG. 10 is a schematic explanatory view of another developing device used for carrying out the developing method according to the embodiment of the present invention.

FIG. 11 is a schematic explanatory view showing a state in which the amount of the developer on the developing sleeve is regulated by a regulating rod when the developing method according to the embodiment of the invention is carried out.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 developer 2 image carrier (photoreceptor) 10 developing device 11 developer conveying member (developing sleeve) 11a magnet roller 13 regulating member C carrier T toner

Claims (1)

[Claims] 1. A developer containing a toner and a carrier is supplied onto a developer conveying member, the amount of the developer on the developer conveying member is regulated by a regulating member, and then the developer conveying member is used to In the developing method, in which the developer is conveyed to a developing area facing the image carrier, and the toner in the developer is supplied from the developer conveying member to the image carrier to perform development, the developer is conveyed to the developing area. The developer carrying amount of the developer carrying member is 0.7 to 5.0 mg / cm ^2.
In addition to the above range, the developer has a corrected bulk specific gravity of 0.28 to 0.37 and an angle of repose of 38 ° to 52 °.
The developing method is characterized by using a material in the range of.