JPH0588540A - Developing device - Google Patents

Abstract

PURPOSE:To provide the developing device which uses a two-component developer and prevents the developer from being stagnated and compressed within a space enclosed by a developer layer thickness regulating member above a developer carrying member and a guiding and transporting surface for pushing back the developer, etc. CONSTITUTION:The developer layer thickness regulating member 22 is disposed on the upstream side in a developer transporting direction of the uppermost position P of the developer carrying member 20 and the side opposite from the developer layer thickness regulating member 22 side of the guiding and transporting surface 25a for pushing back the developer extending from the developer layer thickness regulating member 22 to the upstream side in the developer transporting direction is inclined to the side approximate to the developer carrying member 20 side from a horizontal position. Then, the space enclosed by the developer layer thickness regulating member 22 above the developer carrying member 20 and the guiding and transporting surface 25a for pushing back the developer is gradually narrowed in the state relatively along the outside surface of the developer carrying member 20 toward the developer layer thickness regulating member 22 and the push back of the developer by the guiding and transporting surface 25a is gradually and smoothly executed. The stagnation, etc., of the developer do not arise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, and more particularly to a developing device using a two-component developer composed of toner and carrier.

[0002]

2. Description of the Related Art In an electrophotographic or electrostatic recording type image forming apparatus, a two-component developer consisting of toner and carrier is used to visualize a latent image formed on an image carrier as a toner image. Many developing devices are also used. In this case, the toner in the developing device is charged by the friction with the carrier, and is smoothly moved to the latent image on the image carrier during the developing operation.

An example of such a developing device will be described with reference to FIG. 4. Reference numeral 101 in the drawing is a developing device in which a two-component developer T composed of a toner and a carrier is magnetically attracted to the outer peripheral surface thereof by the action of an internal magnet 102 to rotate. A developing blade serving as a developer carrier, and a developing blade serving as a developer layer thickness regulating member that regulates the layer thickness of the developer T adsorbed to the developing sleeve 101 to a uniform thin layer above the developing sleeve 101. 103 is provided.

Further, the developer T is agitated and conveyed to the developing chamber 110 below the developing sleeve 101 and the agitating chamber 111 adjacent to the developing chamber 110 via a partition 112.
The second stirring / conveying means 104 and 105 are provided, and the developing blade 103 above the developing sleeve 101.
On the right side of, a carrier return 106 having a horizontal guide-conveying surface 106a for smoothly conveying the developer T to the developing blade 103 side with the rotation of the developing sleeve 101 and pushing back the excessive developer is disposed. Has been done. A toner concentration detecting means 107 for detecting the toner concentration in the developer T is disposed on the guide and transport surface 106a of the carrier return 106.

That is, since openings are provided in front of and behind the partition wall 112 (above and below the plane of the paper in FIG. 4), the developer T is rotated by the rotation of the first and second agitating and conveying means 104 and 105. The toner and carrier are transported while being sufficiently stirred,
It is circulated between the developing chamber 110 and the stirring chamber 111. In this case, the toner is sufficiently rubbed by the carrier and charged to a predetermined electric charge. On the other hand, the developer T in the developing chamber 110 is pumped up to the developing sleeve 101 side by the action of the magnet 102, and the developing blade 1 rotates as the developing sleeve 101 rotates.
It is transported to 03.

A part of the transported developer T is regulated by the developing blade 103 into a uniform thin layer, and then transported to a portion (developing area) facing the photosensitive drum 120 which is an image carrier, and only the toner is transported. While being subjected to the developing work, the developer T having the lowered toner concentration is returned to the developing chamber 110. In addition, the rest of the transported developer T is the carrier return 1
It is returned to the stirring chamber 111 side along the guide transport surface 106a of 06. The toner is replenished on the stirring chamber 111 side.

[0007]

However, in the developing device 100 as described above, the developer T conveyed by the developing sleeve 101 is caused by the developing blade 103, the horizontal guide conveying surface 106a of the carrier return 106 and the developing sleeve 101. There is a problem that it stays in the enclosed space and receives a strong compressive force.

Therefore, if a developing operation is carried out for a long time by the developing device 100, the developer T is charged up due to the compression phenomenon of the developer T or the fluidity of the developer T is lowered. There is a problem that the density of the formed image is reduced, the image is extremely rough, and fogging is generated. In particular, the developer T using a soft toner having improved fixability to obtain a full-color, high-quality image is strongly affected by compression, and thus the above-mentioned problem is likely to occur.

Further, in the developing device 100,
Since the flow of the developer T around the toner concentration detecting means 107 of the developer T becomes worse than that on the surface side of the developing sleeve 101, the toner concentration detecting means 107 cannot accurately detect the toner concentration. Device 100
However, when an image having a large number of image portions and a high image density is formed, the density is greatly reduced, and there is a problem that an image having a constant density cannot be stably obtained.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a space in a space surrounded by a developer layer thickness regulating member above a developer carrying member and a guide transporting surface of the developer. In order to provide a developing device using a two-component developer in which the developer does not stay and is not compressed.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a developer carrying member carrying a two-component developer and carrying the developer to a developing area facing the image carrying member. A developer layer thickness regulating member that regulates the layer thickness of the developer on the developer carrier conveyed to the area, and the developer carrier thickness upstream side from the developer layer thickness regulating member by the developer carrier. In a developing device having a developer guide / conveyance surface formed on its upper surface, the developer layer thickness regulating member is disposed upstream from the uppermost position of the developer carrier in the developer conveying direction, and the developer is conveyed. It is characterized in that the side opposite to the developer layer thickness regulating member side of the guide surface is inclined from the horizontal position to the side closer to the developer carrier side.

[0012]

The developer carried by the developer carrier to the developing area side is partially regulated by the developer layer thickness regulating member,
The developer is pushed back to the upstream side in the rotation direction of the developer carrier along the guide transport surface, but in this case, the retention and compression of the developer easily occur.

Therefore, in the present invention, the developer layer thickness regulating member is disposed upstream of the uppermost position of the developer carrier in the developer conveying direction, and the developer layer thickness regulating member on the guide conveying surface of the developer is disposed. The opposite side was inclined from the horizontal position in the direction closer to the developer carrying member side. For this reason, the space formed by the developer carrier, the developer layer thickness regulating member, and the guide transporting surface of the developer is relatively along the outer surface of the developer carrier toward the developer layer thickness regulating member. The pressure gradually becomes narrower, and the developer guiding / conveying surface gradually and smoothly pushes back the developer, so that the developer does not stay and are not compressed in the space.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, a first embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a developing device 2 having a two-component developer composed of toner and carrier on one side of a photosensitive drum 1 which is an electrophotographic photosensitive member (image bearing member) of an image forming apparatus such as a copying machine.
Shows the state in which is positioned. As shown in FIG. 1, the developing device 2 includes a developing container 10 as a main body.
A developing sleeve 20 as a developer carrier, first and second agitating and conveying means 23 and 24 for the developer, a carrier return 25 as a guide conveying member for the developer T, and a toner in the developer T. The toner density detecting means 26 for detecting the density is provided.

The developing container 10 is divided into a developing chamber 12 and a stirring chamber 13 by a partition wall 11 extending in a direction perpendicular to the paper surface of FIG. 1, and toner and carrier are contained in the developing chamber 12 and the stirring chamber 13. A two-component developer T mixed with is stored. Then, in order to collect the excess developer T in the developing chamber 12 to the stirring chamber 13 side, the partition wall 11
In order to connect the inside of the developing chamber 12 and the inside of the stirring chamber 13 to each other, the partition wall 11 is provided with openings on both front and back sides of the paper surface of FIG.

The developing sleeve 20 is rotatably supported at a position facing the photosensitive drum 1 above the developing chamber 12 of the developing container 10, and a magnet 21 serving as a magnetic field generating means is provided inside the developing sleeve 20. It is arranged in a fixed state.
The developing sleeve 20 is made of a non-magnetic material and is rotated in the direction of the arrow in FIG. Further, the magnet 21 is formed with, for example, a developing pole S1 used in the developing operation and carrier poles N1, N2, N3, S2 for transporting the developer T.

The developing blade 22 is made of a non-magnetic material such as aluminum and has a photosensitive drum 1 and a developing sleeve 2.
0 is arranged at a position upstream of the developing area in the rotational direction of the developing sleeve 20 with a predetermined gap with the developing sleeve 20. The developing blade 22 regulates the layer thickness of the developer T, which is adsorbed and held on the outer peripheral surface of the developing sleeve 20 by the action of the magnet 21 and is conveyed to the developing area, to a uniform thin layer.

The carrier return 25 is attached to one side of the developing blade 22 above the developing sleeve 20 so as to extend to the upstream side in the rotating direction of the developing sleeve 20, and is on the lower plane facing the developing sleeve 20 side. Has a developer guiding and conveying surface 25a. The developing blade 22 and the carrier return 25 form a developer regulating portion.

The toner concentration detecting means 26 is the carrier return 2
5, the detection surface 26a thereof is arranged so as to form a part of the guide transport surface 25a of the carrier return 25. Since the guide transport surface 25a of the carrier return 25 forms a part of the circulation path of the developer T from the developing chamber 12 toward the stirring chamber 13, the toner concentration detecting means 26 ensures that the toner concentration in the developing chamber 12 is appropriate. Will be detected. In the present embodiment, the toner concentration detecting means 26 is of the developer reflection type, but it may be one which detects the toner concentration via the inductance of the developer T.

The first and second agitating / conveying means 23 and 24 are disposed below the developing chamber 12 and the agitating chamber 13 along the developing sleeve 20, and their types are spiral around the rotary shafts 23a and 24a. Since the blade type members 23b and 24b are of the screw type, the rotation of the developer member T causes the developer T to be conveyed while being stirred in its axial direction, that is, in the direction parallel to the developing sleeve 20. In this case, the blade members 23b, 2 of the first and second stirring and conveying means 23, 24
Since the spiral direction of 4b is opposite,
If the first and second agitating / conveying means 23 and 24 rotate in the same direction as indicated by the arrow, the developer T is conveyed in opposite directions different from each other by 180 degrees.
Therefore, the developer T is circulated between the developing chamber 12 and the agitating chamber 13 through the openings at both ends of the partition wall 11, and the first and second agitating / conveying means 23 and 24 cause the toner and the carrier to flow. And are well mixed, and the toner is in sufficient contact with the carrier to be tribocharged as needed for the developing operation. Then, the toner T and the carrier are sufficiently mixed, and the developer T having the toner sufficiently charged is conveyed to the developing chamber 12 through the stirring chamber 13.

The toner is replenished on the side of the agitating chamber 13 through a replenishing tank (not shown), but the replenishment amount is the amount corresponding to the toner concentration signal in the developer T from the toner concentration detecting means 26. Done.

That is, the developer T in the developing chamber 12 adsorbed and held (carried) on the outer peripheral surface of the developing sleeve 20 by the action of the magnetic force of the magnet 21 is layered by the developing blade 22 as the developing sleeve 20 rotates. It is transported to the developing area while its thickness is regulated. Then, in the developer conveyed to this developing area, only the toner is moved toward the latent image on the photosensitive drum 1 by the action of the developing bias voltage applied to the developing sleeve 20, and the latent image is visualized as a toner image. Image and develop. Then, after this developing operation is completed, the developer T having the lowered toner concentration is removed from the developing sleeve 2.
With the rotation of 0, the toner is again conveyed into the developing chamber 12, and by the action of the magnetic poles N2 and N3, which are repulsive magnetic poles of the magnet 21, at the position of the magnetic pole N3, from the developing sleeve 20 onto the first stirring and conveying means 23 of the developing chamber 12. It is dropped and collected. Then, the developer T is further drawn up from the developing chamber 12 onto the developing sleeve 20 at the position of the magnetic pole N2.

Further, in the developer regulating portion, the developer T which has not been conveyed to the developing area is rotated along the guide conveying surface 25a of the carrier return 25 in the rotating direction of the developing sleeve 20 as shown by the arrow in FIG. It is pushed back to the upstream side and the partition wall 1
It is dropped over the upper part of 2 onto the second stirring and conveying means 24 of the stirring chamber 13. The falling developer T is mixed with the developer T just mixed with the replenishment toner, and is conveyed again to the developing chamber 12 side together with the second agitating and conveying means 24.

The developer T is conveyed to the developing blade 22 side as the developing sleeve 20 rotates, but the developer T not conveyed to the developing area is guided and conveyed by the developing sleeve 20, the developing blade 22 and the carrier return 25. The guide transport surface 25a of the carrier return 25 does not stay in the developer regulation push-back space S surrounded by the surface 25a or the like and is not compressed.
It is necessary to be smoothly transported to the side of the stirring chamber 13 along.

Therefore, in the present invention, the developing blade 22 is located slightly above the uppermost portion P of the developing sleeve 20.
Is arranged on the upstream side in the rotation direction of
The side of the partition wall 11 opposite to the side of the developing blade 22 of the guide transport 25a is inclined to the side of the lower developing sleeve 20.

Thus, the developing blade 22 is arranged upstream of the uppermost portion P of the developing sleeve 20 in the rotational direction of the developing sleeve 20, and the guide conveying surface 25 of the carrier return 25.
Since the partition 11 side of a is inclined downward to the developing sleeve 20 side, the developer regulation push-back space S up to the developing blade 22 is gradually narrowed, and the developer moved to the developing blade 22 side by the developing sleeve 20. T is gradually regulated by the guide / conveying surface 25a of the carrier return 25, and the excessive developer is pushed back to the stirring chamber 13 side as shown by the arrow in FIG. Therefore, the developer T is not retained and compressed in the developer regulation push-back space S. Further, in particular, since the partition 11 side of the guide conveying surface 25a of the carrier return 25 is inclined downward, the developer T pushed back by the guide conveying surface 25a is also influenced by gravity along the guide conveying surface 25a. Therefore, the lower stirring chamber 13 side can smoothly drop and move.

As described above, the developing blade 22 and the guide conveying surface 25a of the carrier return 25 are positioned with respect to the developing sleeve 20 as described above, and the developer regulating push-back space S is set.
Is narrowed toward the developing blade 22 side in a natural manner. Therefore, the developer T smoothly flows in the developer regulation push-back space S, and the developer T stays and is not compressed. Absent. Therefore, the developer T will not be charged up or the fluidity will be reduced, and the image will not be reduced in density, and the image will not be blurred or fogged. Further, since the flow of the developer T along the detection surface 26a of the toner concentration detecting means 26 is improved, the toner concentration detecting means 26 can detect an appropriate toner concentration.

In particular, the present invention uses a soft toner having an improved fixing property in order to obtain a full-color, high-quality image.
Moreover, it is effective when a toner having a small particle size and a sharp particle size distribution is used. When a two-component developer T using such toner is used to form an image using, for example, a conventional type developing device 100 shown in FIG.
At the time when the image was formed on about 00 sheets of transfer material, the highlight part of the image became extremely noticeable and the solid part of the image became blurred.

At this point, when the toner in the developer T is taken out and the surface of the toner is observed with an electron microscope, fine particles of hydrophobic colloidal silica, which is considered to contribute to fluidity, are buried in the toner. Therefore, the developer T
It is considered that the fluidity of the image deteriorates and the entire image becomes rough. Incidentally, when hydrophobic colloidal silica was added to the developer T in this state, an image free of graze was obtained. That is, in a toner such as a color toner that is softened in consideration of fixability, the developer T stays in the vicinity of the guide transport surface 106a of the carrier return 106 shown in FIG.
The developer T itself receives a compressive force due to the magnetic force, and the hydrophobic colloidal silica externally added to the developer T is strongly pressed against the toner, and if image formation is performed in the image device 100 for a long time, the toner T It is conceivable that the silica is embedded in the developer and the fluidity of the developer T is lowered.

On the other hand, when an image is formed with the developer T using the above toner in the developing device 2 according to the present invention, the image is rugged even if the image is formed on 30,000 or more transfer materials. There wasn't. In this case, the durable developer T
And take out the surface of the toner with an electron microscope.
It was found that the fine powder of hydrophobic colloidal silica was almost the same as that of the new developer T, although it was somewhat buried in the toner. This is because the flow of the developer T in the developer regulation push-back space S is improved and the compression of the developer T is reduced.

Here, in order to produce a toner having a sharp particle size distribution, for example, a predetermined toner material is melt-kneaded, the kneaded product is cooled and then pulverized, and the pulverized powder is precisely classified to obtain a predetermined particle size distribution. And / or a method of preparing a toner having a volume average particle diameter.

As a method for precisely classifying the pulverized powder, the pulverized powder is classified by a classifying means such as a fixed wall type air classifier, and the obtained classified powder is further divided into a multi-division classifier utilizing the Coanda effect, for example, Japanese Examples include a method of precisely removing fine powder and coarse powder at the same time with a multi-division classifying means such as an elbow jet classifier manufactured by Iron Mining Co., Ltd. to adjust a toner having a predetermined particle size distribution and / or volume average particle size. ..

In the present invention, the toner means colored resin particles (containing a binder resin, a colorant, and optionally other additives) themselves, and an external additive such as hydrophobic colloidal silica fine powder or titanium oxide fine powder. It includes colored resin particles that are added externally.

Examples of the binder resin used in the toner include styrene-based polymers such as styrene-acrylic acid ester resins or styrene-methacrylic acid ester resins or polyester resins. In particular, when considering the color mixture when fixing color toner, (Wherein R is an ethylene or propylene group, x and y are positive integers of 1 or more, and the average value of x + y is 2 to 10), or a bisphenol derivative represented by the formula or a substituted product thereof. And a carboxylic acid component such as a divalent or higher carboxylic acid or an acid anhydride thereof, or a lower alkyl ester thereof (eg, fumaric acid, maleic acid, maleic anhydride, phthalic acid, terephthalic acid). The polycondensed polyester resin is more preferable because it has sharp melting characteristics.

Colorants suitable for the purposes of the present invention include the following pigments or dyes. In the present invention, CIDsiperse Y164, CISolvent Y77 and C.
Colorants such as I.Solvent Y93 are not recommended.

Examples of the dye include C.I. I Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Mordant Red 30, C.I. I. Direct Blue 1,
C. I. Direct Blue 2, C.I. I. Assid blue 9, C.I. I. Assid blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. There is Modant Blue 7.

Examples of pigments include Naphthol Yellow S, Hansa Yellow G, Permanent Yellow NCG, Permanent Orange GTR, Pyrazolone Orange, Benzidine Orange G, Permanent Red 4R, Watching Red Calcium Salt, Brilliankamine 3B, First Violet B, Methyl Violet. There are rake, phthalocyanine blue, fast sky blue, and indanthrene blue BC.

In particular, disazo yellow, insoluble azo and copper phthalocyanine are preferable as the pigment, and basic dye or oil-soluble dye is preferable as the pigment.

Particularly preferably, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 1
4, C.I. I. Pigment Yellow 12, C.I. I. Pigment Red 5, C.I. I. Pigment Red 3, C.I. I.
Pigment Red 2, C.I. I. Pigment Red 6,
C. I. Pigment Red 7, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 16 or a copper phthalocyanine-based pigment which is a Ba salt in which 2 to 3 carboxybenzamidomethyl groups are substituted on the phthalocyanine skeleton.

As the dye, C.I. I. Solvent Red 4
9, C.I. I. Solvent Red 52, C.I. I. Solvent Red 109, C.I. I. Solvent Red 12, C.I.
I. Solvent Red 1, C.I. I. Solvent Red 3
b.

The content of the colorant is 12 parts by weight or less, and preferably 0.5 to 7 parts by weight, based on 100 parts by weight of the binder resin for the yellow toner which sensitively reflects the transparency of the OHP film. Parts by weight are desirable. When it is 12 parts by weight or less, the reproducibility of green, red and flesh color, which are mixed colors of yellow, is poor.

For magenta toner and cyan toner, 15 parts by weight or less relative to 100 parts by weight of the binder resin,
It is more preferably 0.1 to 9 parts by weight or less.

In the case of a black toner which is used in combination with two or more colorants, the addition of 20 parts by weight or more of the total amount of colorants is likely to cause spent on the carrier, and more colorants are exposed on the toner surface. As a result, the fusion of the toner on the photosensitive drum increases, and the fixing property becomes unstable. Therefore, in the black toner, the amount of the colorant is preferably 3 to 15 parts by weight with respect to 100 parts by weight of the binder resin.

A preferable combination of colorants for forming a black toner is a combination of a disazo yellow pigment, a monoazo red pigment and a copper phthalocyanine blue pigment. The mixing ratio of each pigment is such that the ratio of yellow pigment, red pigment and blue pigment is 1: 1.5 to 2.5 :.
0.5 to 1.5 is preferable.

When the toner used in the present invention is negatively charged, it is also preferable to add a charge control agent in order to stabilize the negatively charged characteristics. At that time, a colorless or light-colored negative charge control agent that does not affect the color tone of the toner is preferable. Examples of the negative charge control agent include metal complexes of alkyl-substituted salicylic acid, for example, organic-affiliated complexes such as chromium or zinc complexes of ditertiarybutylsalicylic acid. When the negative charge control agent is added to the toner, it is preferably added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the binder resin.

In the present invention, magnetic particles are used as a carrier in the developer used. The magnetic particles have a particle size of 30 to 100 μm, preferably 40 to 80 μm,
Electric resistance value is 10 ⁷ Ω · cm or more, preferably 10 ⁸ Ω
-Cm or more, more preferably 10 ⁹ to 10 ¹² Ω-cm
Ferrite particles (maximum magnetization 60 emu /
Resin coated on g) can be preferably used.

To measure the resistance value of magnetic particles such as ferrite particles or resin-coated ferrite particles, a sandwich type cell having a measuring electrode area of 4 cm ² and an electrode gap of 0.4 cm was used. It is a value obtained by applying an applied voltage E (V / cm) between the quantity electrodes under pressure and measuring the resistance value of the magnetic particles from the current flowing in the circuit.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Will be explained. The same reference numerals are given to those having the same functions as those according to the first embodiment, and the description thereof will be omitted.

In the developing device 2 according to the present embodiment, as shown in FIG.
The capacity of the developing device 2 is reduced and the developing device 2 is downsized. On the other hand, in the present embodiment as well, as in the case of the first embodiment, the developing blade 22 is disposed slightly upstream of the uppermost portion P of the developing sleeve 20 in the rotational direction of the developing sleeve 20, and the carrier return 25 is guided and conveyed. The side of the partition wall 11 opposite to the developing blade 22 of the surface 25a is connected to the developing sleeve 2 below.
It was inclined to the 0 side.

Thus, in this embodiment, the capacity of the developing chamber 12 becomes small, and especially the developer T in the developing chamber 12 and the like is reduced.
Changes in the circulation flow of, but even in this case,
First, by increasing the rotation speed of the agitating / conveying means 23 or increasing the pitch of the rotary blades 23b, the circulating flow of the developer T similar to that in the first embodiment, especially from the developer regulating push-back space S Since the circulation flow of the developer T to the stirring chamber 13 side can be secured, the same effect as that of the first embodiment can be obtained in this embodiment.

As shown in FIG. 3, even when the upper portion of the developing blade 22 is further inclined toward the carrier return side to further downsize the developing device 2, the developing device 2 shown in FIG. Similar to the above, the same effect as the first embodiment can be obtained.

[0054]

As is apparent from the above description, according to the present invention, the space formed by the developer carrying member, the developer layer thickness regulating member, and the guide transporting surface of the developer is used as the developer layer thickness regulating member. Since it gradually narrowed toward the outer surface of the developer carrying member, the regulation and push-back of the developer by the guide transport surface of the developer are gradually smoothed, and the retention and compression of the developer in the space are performed. Does not occur.

[Brief description of drawings]

FIG. 1 is a sectional view of a developing device and the like according to a first embodiment.

FIG. 2 is a sectional view of a developing device and the like according to a second embodiment.

FIG. 3 is a sectional view of a developing device and the like according to a modified embodiment of the second embodiment.

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 image carrier (photosensitive drum) 20 developing sleeve (developer carrier) 22 developing blade (developer layer thickness regulating member) 25a guide transport surface P uppermost position T developer

Claims (2)

[Claims] 1. A developer carrying member carrying a two-component developer and carrying the developer to a developing area facing the image carrying body, and a developer carried on the developer carrying body carried to the developing area. And a developer layer thickness regulating member for regulating the layer thickness of the developer layer thickness regulating member, and a developer guiding and conveying surface is formed upstream of the developer layer thickness regulating member by the developer carrier in the developer conveying direction. , The developer layer thickness regulating member is disposed upstream from the uppermost position of the developer carrier in the developer transport direction, and the developer transporting guide surface is provided on the opposite side of the developer layer thickness regulating member side. A developing device, wherein the developing device is inclined from a horizontal position to a side closer to the developer carrying member side. 2. The developing device according to claim 1, wherein a developer concentration detecting unit is provided in the developer transport guide surface.