JP2571286B2 - Developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an electrophotographic apparatus such as an electrophotographic printer or a copying machine for visualizing an electrostatic latent image on an electrostatic latent image carrier. The present invention relates to a developing device.

(Prior Art) Conventionally, in an optical printer such as a laser printer or a liquid crystal printer or a PPC copying machine, an electrophotographic method is widely adopted as an image forming method.

In the electrophotographic method, basically, the surface of a photosensitive drum, that is, an electrostatic latent image carrier is uniformly charged, an electrostatic latent image is formed by exposure, and then the electrostatic latent image is developed with toner. Then, the image is visualized and then transferred and fixed on a recording paper to obtain a hard copy.

In this type of electrophotographic apparatus, the developing device has a developing sleeve rotatably supported by a toner supply unit, and the toner adheres to the surface of the electrostatic latent image carrier as the developing sleeve rotates. (See Japanese Patent Publication No. Sho 62-12510).

FIG. 10 is a sectional view of the conventional developing device. In the figure, a developing sleeve 22 is rotatably supported in a toner supply section 21, and this developing sleeve 22 is a conductive metal core.
23 is formed by coating conductive rubber 24 having a JIS Shore hardness of 30 to 50 mm. On the upper part of the developing sleeve 22,
A doctor blade 25 made of a conductive material is pressed against the surface of the developing sleeve 22 at a predetermined pressure by the urging force of a spring 26. The developing sleeve 22 is in pressure contact with the electrostatic latent image carrier 27 by a method not shown.

In the developing device having the above configuration, the rotation direction of the electrostatic latent image carrier 27 and the rotation direction of the development sleeve 22 are set to follow directions,
The peripheral speed of the electrostatic latent image carrier 27 is V _D , and the peripheral speed of the developing sleeve 22 is
When a V _P, the value of V _D / V _P is defined to 1.5. In such a developing device, a large load is applied to the developing sleeve 22 by the pressure contact of the doctor blade 25 and the pressure contact of the electrostatic latent image carrier 27.

 FIG. 9 is a gear arrangement diagram in the developing device.

In the figure, a developing sleeve 22 is rotatably supported in a toner supply unit 21, rotates in a direction b as the electrostatic latent image carrier 27 rotates in a direction a, and rotates only in a thickness regulated by a regulating member 28. Is supplied to the surface of the electrostatic latent image carrier 27. Reference numeral 30 denotes a toner holding member.

The developing sleeve 22 rotates integrally with the developing sleeve gear 31, and is rotated by an intermediate gear 32 that meshes with the developing sleeve gear 31.

In the figure, A is the center of the electrostatic latent image carrier 27, B is the center of the developing sleeve 22, and C is the center of the intermediate gear 32.

In the above-described conventional developing device, the center C of the intermediate gear 32 is
Is disposed on a line segment inclined by 45 ° with respect to a line segment AB connecting the center A of the electrostatic latent image carrier 27 and the center B of the developing sleeve 22 with respect to the center B of the developing sleeve 22. . In such a configuration, the developing sleeve 22 that transports the toner 29 is connected to the intermediate gear 32 and the developing sleeve gear by a drive system (not shown).
Rotated via 31.

(Problems to be Solved by the Invention) However, in the developing device having the driving mechanism having the above configuration, when a small pressure is applied to the regulating member 28 to reduce the load applied to the developing sleeve 22, both ends and the center of the recording paper are Printing can be performed on the part,
When the pressure applied to the recording paper is increased, the print density at the central portion of the recording paper decreases, and eventually printing is not performed at the central portion during recording.

At this time, when the surface of the developing sleeve 22 after printing is observed after contact with the electrostatic latent image carrier 27, both ends of the developing sleeve 22 are in contact, but the vicinity of the longitudinal center of the developing sleeve 22 is completely You can see that they are not in contact. The cause of the non-contact is that the shaft of the developing sleeve 22 is bent and developed.

Thus, in the conventional developing device, the regulating member 28
The pressure that can be applied to the developing sleeve is limited, and the printing quality is deteriorated because it is easily affected by the fluctuation of the load applied to the developing sleeve 22.

The present invention solves the problems of the conventional developing device described above,
The vicinity of the center in the longitudinal direction of the developing sleeve can be prevented from coming into contact with the electrostatic latent image carrier, printing can be performed at a uniform density, and printing quality can be prevented from deteriorating. It is another object of the present invention to provide a developing device that can increase the pressure that can be applied to the regulating member.

(Means for Solving the Problems) For this purpose, in the developing device of the present invention, an electrostatic latent image carrier for carrying an electrostatic latent image, and an electrostatic latent image carrier are disposed opposite to the electrostatic latent image carrier. A rotatable developing sleeve which is rotatably fixed by two bearings, and which is rotated by receiving a rotational force on an end side from the bearings to convey charged toner to a developing area; and an upstream of the developing area. A regulating member that is disposed in contact with the surface of the developing sleeve on the side thereof and regulates a toner supply amount; and a toner supply unit that is disposed upstream of the regulating member and supplies toner to the surface of the developing sleeve. Having.

The angle between the direction of the rotational force applied to the developing sleeve and the line connecting the rotation center of the electrostatic latent image carrier and the rotation center of the developing sleeve is 0 to 110, 250 to 360 [゜].
Is set within the range.

In another developing device of the present invention, the shaft diameter of the developing sleeve is d [mm], the distance between two bearings supporting the developing sleeve is l [mm], and The component of the force applied to the axis of the developing sleeve in the direction connecting the rotation center of the body and the rotation center of the developing sleeve is Px
When the weight is [kg weight], the relationship is P _X (l / d ² ) ² ≦ 100.

(Operation) According to the present invention, in the developing device as described above,
An electrostatic latent image carrier for carrying an electrostatic latent image, disposed opposite to the electrostatic latent image carrier, rotatably fixed by two bearings, and rotating at an end side from the bearings; A rotatable developing sleeve that is rotated under a force to convey the charged toner to the developing area, and is disposed in contact with the surface of the developing sleeve at an upstream side of the developing area to regulate a toner supply amount. And a toner supply unit disposed upstream of the regulating member and supplying toner to the surface of the developing sleeve.

The angle between the direction of the rotational force applied to the developing sleeve and the line connecting the rotation center of the electrostatic latent image carrier and the rotation center of the developing sleeve is 0 to 110, 250 to 360 [゜].
Is set within the range.

In this case, in order to rotate the developing sleeve,
When a rotational force is applied to the end of the developing sleeve from the bearing, the supporting portion of the developing sleeve is fixed by the bearing, so that the developing sleeve bends in a direction opposite to the direction of the rotational force.

However, the angle between the direction of the rotational force and the line connecting the rotation center of the electrostatic latent image carrier and the rotation center of the developing sleeve is set in the range of 0 to 110, 250 to 360 [゜]. Therefore, the component of the amount of deflection in the direction in which the developing sleeve escapes from the electrostatic latent image carrier is reduced.

In another developing device of the present invention, the shaft diameter of the developing sleeve is d [mm], the distance between two bearings supporting the developing sleeve is l [mm], and an electrostatic latent image is formed. The component of the force applied to the shaft of the developing sleeve in the direction connecting the rotation center of the carrier and the rotation center of the developing sleeve
When Px (kg weight) is used, the relationship is P _X (l / d ² ) ² ≦ 100.

In this case, the amount of bending of the shaft of the developing sleeve when the shaft is made of an iron-based material can be reduced.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention.

In the figure, a toner supply unit 1 is located above a developing sleeve 3 and contains a toner 6.
Is supplied to the developing sleeve 3 and the regulating member 2 in contact with the developing sleeve 3 and is frictionally charged to a predetermined polarity, and the contact pressure of the regulating member 2 makes the toner 6 uniform and has an optimum thickness. The toner is supplied onto the developing sleeve 3.

The charged toner 6 is carried on the developing sleeve 3 by electrostatic force, and as the developing sleeve 3 rotates, a developing area for visualizing the electrostatic latent image carried on the electrostatic latent image carrier 4, That is, it is transported to the area where the electrostatic latent image carrier 4 and the developing sleeve 3 are in contact. At this time, the length in the rotation direction of the contact area of the developing sleeve 3, that is, the nip width is 2 mm.

Then, the toner 6 that does not contribute to the visible image is collected by the toner supply unit 1 as the developing sleeve 3 rotates. The rotational force applied to the developing sleeve 3 for transporting the toner 6 is transmitted to the intermediate gear 8 by a drive system (not shown) and transmitted to the developing sleeve gear 7 fixed to the developing sleeve shaft. While the electrostatic latent image carrier 4 and the intermediate gear 8 rotate in the direction a in the figure, the developing sleeve 3 rotates in the direction b.

It is preferable that the peripheral speed of the developing sleeve 3 is at least 1 times the peripheral speed of the electrostatic latent image carrier 4, and in this embodiment, the peripheral speed of the electrostatic latent image carrier 4 is 30 mm / s. The peripheral speed of the sleeve 3 is set to 60 mm / s, which is twice as large.

Here, the center of the intermediate gear 8 is located on an extension of a horizontal line segment AB connecting the center A of the electrostatic latent image carrier 4 and the center B of the developing sleeve 3.

The developing sleeve 3 has a metal shaft (shaft diameter d = φ).
8) Molded conductive and elastic rubber is used. Conductive rubber has a rubber hardness of JISA 20 ゜ to 50 ゜ and a resistance value of 10 ² to 10 ¹⁰ Ωc to obtain an appropriate nip width
A material having a characteristic of m is preferable, and the material may be any of chloroprene rubber, nitrile rubber, and the like.

Since the surface roughness of the developing sleeve 3 affects the toner conveyance amount, the surface roughness is preferably 0.2 to 10 μm Rz (ten-point average roughness). Further, various polymers may be applied to the surface of the rubber in order to enhance the frictional charging effect and the friction resistance imparted to the toner 6.

In this embodiment, the rubber hardness is 30 ° and the resistance value is 10 ⁵
Chloroprene rubber having a Ωcm, a surface roughness of 1.8 to 2.1 μm Rz, and a developing sleeve 3 diameter of 20 mm is used.

Further, it is preferable to use an elastic material for the regulating member 2, and polyurethane rubber having a rubber hardness of 78 ° is used.
In addition to rubber, a thin metal plate such as stainless steel or phosphor bronze, a high molecular compound material such as nylon or polyester, or a material obtained by applying the above high molecular compound on rubber or metal may be used. In order to uniformly and thinly adhere the toner 6 on the developing sleeve 3 and to achieve optimal triboelectric charging, it is preferable that the rubber has a hardness of 40 to 90 (JISA).

The electrostatic latent image carrier 4 can be made of organic, Se, amorphous silicon, CdS, or the like.
In this embodiment, an organic electrostatic latent image carrier is used.

As the toner 6, either a one-component toner or a two-component toner may be used. In this embodiment, the average particle diameter is 9 μm.
m non-magnetic toner having a negative polarity is used.

Further, as the developing sleeve gear 7 and the intermediate gear 8,
The module 1 having 14 and 26 teeth, respectively, is used.

In order to obtain a preferable print density, the nip width between the developing sleeve 3 and the electrostatic latent image carrier 4 needs to be set to about 2 mm. In order to obtain this nip width, the contact amount between the developing sleeve 3 and the electrostatic latent image carrier 4 is set to about 50 μm from FIG.

Also, at least about 1.7mm to obtain acceptable print density
Nip width, that is, a contact amount of 38 μm is required. Therefore, the allowable amount of deflection δ _{x in} the horizontal direction in which the developing sleeve 3 escapes from the electrostatic latent image carrier 4 is δ _x = 50−38 = 12 μm. When the developing sleeve 3 is brought into contact with the electrostatic latent image carrier 4 with a contact amount of 50 μm, the minimum rotational force F ₅ (described later) required to rotate the developing sleeve 3 is 1.4 kg weight.

Next, FIG. 3 is a diagram showing a force applied to the developing sleeve.

By changing the angle θ of the line segment AB and the line segment BC, i.e., shows the results of printing by changing the direction of the rotational force F ₅ applied to the developing sleeve 3 in FIGS. 4 and 5.

Figure 4 is 0 the direction angle α of F ₅ between the line segment AB rotational force
This shows the print density (optical density) at the center of the recording paper when changed to 360 °. Here, the density at both ends of the recording paper is about 1.35. Further, it can be seen that when the angle α exceeds 110 °, the print density rapidly decreases, and when the angle α exceeds 250 °, the print density rapidly increases.

FIG. 5 is a diagram showing the relationship between the angle α and the uniformity of printing on the entire surface of the recording paper. It can be seen that when the angle α exceeds 110 °, the uniformity decreases, and becomes higher around 250 °.

That is, print density, the angle between the directions of the rotational force F ₅ line segment AB alpha to 0 ° to 110 DEG or 250 DEG to 360 within DEG in order to perform good printing in uniformity of printing There is a need.

In FIG. 3, F ₂ is a vertical force that balances the force of bringing the developing sleeve 3 into contact with the electrostatic latent image carrier 4,
The direction of the normal force F ₂ is toward the center of the developing sleeve 3,
In the case of the present embodiment, the direction is the horizontal direction. F ₁ is the developing sleeve 3
Is the frictional force that the developing sleeve 3 receives due to the friction with the electrostatic latent image carrier 4 when is rotated, and the frictional force F ₁
The size is F ₁ = μ ₁ F ₂ . Here, mu ₁ is an electrostatic latent image bearing member 4, the developing sleeve 3, a dynamic friction coefficient between the toner 6. The direction of the frictional force F ₁ is a tangential direction at a point where the frictional force F ₁ contacts the electrostatic latent image carrier 4 on the circumference of the developing sleeve 3. That is, the frictional force F ₁ and the normal force F ₂ is the angle formed is 90 °. F ₃ is a pressing force applied by the regulating member 2 so that the developing sleeve 3 frictionally charges the toner 6 and makes the toner 6 thin, and its direction is from the point where the developing sleeve 3 contacts the regulating member 2 to the center of the developing sleeve 3. Head for.

F ₄ is the regulating member 2 when the developing sleeve 3 is rotating.
Is the frictional force that the developing sleeve 3 receives due to the friction with the developer, and the magnitude is F ₄ = μ ₂ F ₃ . Here mu ₂ is regulating member 2, developing sleeve 3, a dynamic friction coefficient between the toner 6. Direction of the frictional force F ₄ is tangential at the point of contact between the regulating member 2 on the circumference of the developing sleeve 3. That is, the pressing force F ₃ frictional force F ₄ is the angle 90 °, the angle of contact pressure F ₃ and normal force F ₂ is about 65 °.

The dynamic friction coefficients μ ₁ and μ ₂ are governed by the surface roughness and surface material of the developing sleeve 3, the electrostatic latent image carrier 4 and the regulating member 2, the surface material, shape, and particle size of the toner 6.

F ₅ is a rotational force developing sleeve gear 7 receives from the intermediate gear 8, the size of the radius of the developing sleeve 3 r _1, the rotational force F ₅ when the reference circle pitch radius of the developing sleeve gear 7 was r ₂ is , F ₅ = (F ₁ + F ₄ ) × r ₁ / r ₂ = (μ ₁ F ₂ + μ ₂ F ₃ ) × r ₁ / r ₂ , and the direction of the force is substantially the reference circle pitch circle of the developing sleeve gear 7. This is a tangential direction at a point where the intermediate gear 8 comes into contact with the circumference. The direction of the rotational force F ₅ is determined by the installed is the location of the intermediate gear 8. That is, the direction angle of the force between the vertical line segment to the line segment AB rotational force F ₅ line segment AB and the line segment BC is equal to the angle theta. From this fact the construction shown in FIG. 9, the direction of the rotational force F ₅ tilts 45 ° to the electrostatic latent image bearing member 27 side of the perpendicular line to the line segment AB. Further, in the configuration of the developing device of the present invention shown in FIG. 1, the direction of the rotational force F ₅ is the direction perpendicular to the line segment AB. Relationship between the angle alpha between the angle theta and the line segment AB and a line segment AB and the line segment BC and the direction of the rotational force F ₅ From this is almost alpha = 90 ° + theta.

The direction of the force applied to the shaft of the developing sleeve 3 changes depending on the driving method.

FIG. 6 is a diagram showing the direction of the force applied to the developing sleeve shaft by the driving method, FIG. 6 (A) is a diagram showing the direction of the force in the driving method by the gear used in this embodiment, and FIG. 6 (B).
FIG. 4 is a diagram illustrating a direction of a force in a driving method using a belt.

In FIG. 6 (B), reference numeral 9 denotes a developing sleeve pulley fixed to the developing sleeve shaft, and reference numeral 10 denotes an intermediate pulley for applying a rotational force to the developing sleeve 3. Developing sleeve 3
Is transmitted to the intermediate pulley 10 by a drive system (not shown), and is transmitted to the developing sleeve pulley 9 via the belt 11. D indicates the center of rotation of the intermediate pulley 10. Assuming that the tension on the tension side of the belt 11 when the developing sleeve pulley 9 is rotating in the direction b is T ₁ , and the tension on the loose side is T ₂ , the difference T ₁ −T ₂ between the tensions is
This is an effective force for driving the.

The direction of the force applied to the developing sleeve shaft is, as shown in FIG.
There same direction as the direction for receiving the rotational force F _5, that is, the direction of F _6.

In the case of driving by a belt, as shown in FIG. 6 (B), the difference T ₁ −T ₂ between the tension T ₁ on the tension side and the tension T ₂ on the loose side.
Direction, i.e. the direction of F _7. Direction F ₇ is a direction generally toward the center B of the rotation of the developing sleeve 3 to the rotation center D of the intermediate pulley 10. That is, line segment AB and line segment BD
Substantially equal to the angle α and the angle θ and direction of the force of the line segment AB and F ₇ of. As described above, the direction of the force applied to the developing sleeve shaft differs depending on the driving method, and is shifted by about 90 ° when the gear is used and when the belt is used.

 Next, the bending of the developing sleeve shaft will be described.

Direction the developing sleeve shaft flexes during rotation is the opposite direction of the rotational force F _5. From this, the cause of the deflection is the rotational force F ₅
It turns out that it is. As a result of the deflection caused by the rotation force F ₅ [delta] is generated, the longitudinal center portion of the developing sleeve 3 would not in contact with the electrostatic latent image bearing member 4.

Here, assuming that the horizontal component of the amount of deflection δ of the shaft of the developing sleeve 3 is δ _x , the vertical component is δ _y , the horizontal component of the rotational force F ₅ is F _5x , and the vertical component is F _5y , the rotational force F ₅ , the deflection Each component of quantity δ
_{F 5x, F 5y, δ x} , δ y _{is, F 5x = F 5 sinθ F} 5y = F 5 cosθ δ x = δsinθ δ y = δcosθ next, the amount of deflection by the rotational force F _5x [delta] _x is the rotational force F _5y the deflection amount [delta] _y is produced.

Here, the direction that affects the to the developing sleeve 3 changes horizontally from the nip width changes the nip width is found to be horizontal component [delta] _x.

The amount of deflection δ _x of the horizontal component due to the horizontal component F _5x of the rotational force F ₅ can be approximated by a dynamic model as shown in FIG.

^{δ = Pal 2 / 16EI ...... (} 1) I = πd 4/64 , however, [delta]: amount of deflection [μm] P: force [kg Weight] a: the length of the arm (mm) l: span length (mm) d : Diameter [mm] E: Longitudinal elasticity The arm length a in FIG. 7 is determined from the longitudinal center of the bearing on the developing sleeve gear 7 side of the two bearings supporting the developing sleeve 3 in FIG. This corresponds to the distance to the center of the sleeve gear 7 in the longitudinal direction. The span length l is
In the distance between the two bearings fixing the developing sleeve 3,
The diameter d corresponds to the diameter of the shaft of the developing sleeve 3. The longitudinal elastic modulus E is determined by the material of the shaft of the developing sleeve 3. Since the one used in the present embodiment is of iron type, E = 21000 kgf / mm.
It becomes ² . Then, the external force P corresponds to a horizontal component F _5x rotational force F _5. In this embodiment, a = 20 mm, l = 280 mm, d = 8 mm
, And the show dashed line in FIG. 8 is these numerical values as determined horizontal component [delta] _x of the deflection corresponds to the horizontal component F ₅ of the rotational force are substituted into equation (1). The solid line in Figure 8 if not θ is 0 ° shown in FIG. 9, i.e. in the embodiment of the present invention, showing the amount of deflection [delta] _x calculated from the nip width is measured nip width after printing.

As can be seen from FIG. 8, the value calculated from the nip width and the value obtained from the bending calculation formula (1) substantially match. Also,
Using mechanical model the maximum deflection amount of bending of the developing sleeve 3 by the third maximum deflection amount and the pressing force F ₃ and the frictional force F ₄ bend of the developing sleeve 3 and the normal force F ₂ due to the frictional force F ₁ shown in FIG. ,
When determined by the bending of the formula, the horizontal component of the rotational force F ₅
Compared to the amount of deflection [delta] _x of the developing sleeve axis by F _5x, pressing force F ₃ and the developing sleeve 3 by the frictional force F ₄ bend maximum deflection also of the developing sleeve 3 by the normal force F ₂ and the frictional force F ₁ Bending of The maximum bending amount is also sufficiently small, and does not match even when compared with the bending amount calculated from the nip width.

The The developing sleeve 3 is not in contact with the electrostatic latent image bearing member 4 from it due to the horizontal deflection [delta] _x of the shaft of the developing sleeve 3 by the horizontal direction component F _5x rotational force F ₅ the developing sleeve gear 7 receives You can see that.

Horizontal deflection amount [delta] _x of the shaft of the developing sleeve 3 in the above (1) and substituting _{P = F 5x = F 5 sinθ} , δ x = F 5 sinθ · al 2 / 16EI = F 5 sinθ · the ^{al 2 / 16E (πd 4/} 64) = 64al 2 F 5 sinθ / 16πEd 4 ...... (2).

From equation (2), reduction of the arm length a is to reduce the amount of deflection, reduction in span length l, changes in the direction of the rotational force F ₅ by changing the magnification and position of the intermediate gear 8 having a diameter d (Θ
Decrease). It is understood that the larger the modulus of longitudinal elasticity E, the better, but it is preferable to use a developing sleeve shaft made of an iron-based material from the viewpoint of cost and workability, and it is difficult to increase the value of E. Further, since the rotational force F ₅ is a force applied to rotate the developing sleeve 3, the minimum value can not be freely selected will be determined.

Here, as described above, the amount of deflection δ _x in the horizontal direction allowable from the printing result must be 12 μm or less. Therefore, when the value of δ _x is substituted into the above equation (2), δ _x = 64al ² F ₅ sinθ / 16πEd ⁴ ≦ 12 × 10 ⁻³ = 1.273al ² F ₅ sin θ / Ed ² ≦ 12 × 10 ^-3 (3)

It is preferable to improve the above various dimensions so as to satisfy the expression (3). That is, reduction of the arm length a, reduction of the span length l, and expansion of the diameter d are appropriate. Since the shaft of the developing sleeve 3 is generally made of an iron-based material, E = 21000 kg
Weight / mm ² . The length of the arm a is because it is difficult to below the mounting structure on 2mm such as a gear which receives a rotational force F _5, subject to the constraint that the arm length a ≧ 2. When this by substituting the minimum value a = 2 from obtaining the relationship between the horizontal component F ₅ sin [theta rotational force and span length l and the diameter _{^{d, 1.273al 2 F 5 sinθ /}} Ed 4 ≦ 12 × 10 -3 al ² F ₅ sin θ / Ed ⁴ ≦ 9.427 × 10 ^-3 …… (4) 2l ² F ₅ sin θ / Ed ⁴ ≦ 9.427 × 10 ^-3 l ₂ F ₅ sin θ / Ed ⁴ ≦ 4.714 × 10 ^-3 …… ( _{^{5) l 2 F 5 sinθ /}} d 4 · 21000 ≦ 4.714 × 10 -3 l 2 F 5 sinθ / d 4 ≦ 99 F 5 sinθ (l / d 2) is as ² ≦ 99 ...... (6), If the shaft diameter d of the developing sleeve 3 and the distance between the two bearings fixing the developing sleeve 3 are determined so as to satisfy the expression (6), the amount of bending can be reduced.

Then, if by changing the position of the intermediate gear 8 reduces the amount of deflection by changing the direction of the rotational force F _5, in a case of this embodiment,
Since l = 280 mm, a = 20 mm, d = 8 mm, and F ₅ = 1.4 kg weight, when these numerical values are substituted into the above equation (2), δ _x = 64al ² F ₅ sin θ / 16πEd ⁴ = 64 × 20 × 280 ² × 1.4 sin θ / 16 × π × 21000 × 8 ⁴ = 32.5 × 10 ⁻³ sin θ (7) Since [delta] _x of the direction in which the developing sleeve 3 escapes from the electrostatic latent image bearing member 4 must be 12μm or less than the print ^{result, 12 × 10 -3 ≧ 32.5 ×} 10 -3 sinθ sinθ ≦ 0.37 θ ≦ 21.8 ° ≒ 20゜ （（（（（（（８ ８ ８ ８ ８ ８ ８ ８ ８ ８ ８ ８ ８ 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 よ り 、 、 よ り 、 、 、 、 、 8
During ゜), δ _x is 12 μm or more. Therefore, the angle θ must give rotational force F ₅ to be in the range between 0 to 20 ° 160 ° 360 ° to the developing sleeve gear 7.

That is, considering the angle α, α = 90 ° + θ, so that it is between 0 ° and 110 ° and between 250 ° and 360 °.

Further, since the allowable nip width is about 1.7 mm, the allowable bending amount can be increased by bringing the developing sleeve 3 into contact with the electrostatic latent image carrier 4 so that the nip width becomes 2 mm or more. That is, the range satisfying the angle θ is widened. However, increasing the contact amount such wider nip width, the value of the normal force F ₂ shown in FIG. 3 is increased. This horizontal component F _5x rotational force F ₅ frictional force F ₁ is increased to increase the. Since the amount of deflection due to the increase of the horizontal component _F5x is larger than the amount of contact for increasing the nip width, it is practically impossible. The developing sleeve 3
Since it is possible to take a nip width with a small rotational force F ₁ by lowering the rubber hardness, the limit value of the rubber hardness which can be produced as a conductive rubber roller is 20 ° to 30 °, this also not Near possible.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the gist of the present invention.
They are not excluded from the scope of the present invention.

(Effects of the Invention) As described in detail above, according to the present invention, in the developing device, an electrostatic latent image carrier for carrying an electrostatic latent image;
The charged toner is disposed opposite to the electrostatic latent image carrier, is rotatably fixed by two bearings, and is rotated by receiving a rotational force on an end side from the bearings, so that charged toner is developed. A rotatable developing sleeve that conveys the toner to a developing member, and a regulating member that is disposed in contact with the surface of the developing sleeve on the upstream side of the developing area and regulates a toner supply amount.
A toner supply unit disposed upstream of the regulating member for supplying toner to the surface of the developing sleeve.

The angle between the direction of the rotational force applied to the developing sleeve and the line connecting the rotation center of the electrostatic latent image carrier and the rotation center of the developing sleeve is 0 to 110, 250 to 360 [゜].
Is set within the range.

In this case, in order to rotate the developing sleeve,
When a rotational force is applied to the end of the developing sleeve from the bearing, the component of the amount of deflection in the direction in which the developing sleeve escapes from the latent electrostatic image bearing member decreases.

Therefore, it is possible to prevent the vicinity of the center of the developing sleeve in the longitudinal direction from coming into contact with the electrostatic latent image carrier, so that printing can be performed at a uniform density and printing quality is prevented from deteriorating. be able to.

Further, the pressure that can be applied to the regulating member can be increased.

In another developing device of the present invention, the shaft diameter of the developing sleeve is d [mm], the distance between two bearings supporting the developing sleeve is l [mm], and an electrostatic latent image is formed. The component of the force applied to the shaft of the developing sleeve in the direction connecting the rotation center of the carrier and the rotation center of the developing sleeve
When Px (kg weight) is used, the relationship is P _X (l / d ² ) ² ≦ 100.

In this case, the amount of bending of the shaft of the developing sleeve when the shaft is made of an iron-based material can be reduced, so that not only can the cost of the developing device be reduced, but also the processability can be improved. .

[Brief description of the drawings]

FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing the relationship between the contact amount of the developing sleeve and the electrostatic latent image carrier and the nip width. FIG. 3 is a diagram showing the force applied to the developing sleeve.
FIG. 4 is a diagram showing the relationship between the angle α and the printing density, FIG. 5 is a diagram showing the relationship between the angle α and the uniformity of printing over the entire surface of the recording paper, and FIG. 6 shows the direction of the force applied to the developing sleeve shaft by the driving method. FIG. 6 (A) is a diagram showing the direction of force in the driving method using gears used in the present embodiment, FIG. 6 (B) is a diagram showing the direction of force in the driving method using a belt, and FIG. FIG. 8 is a mechanical model diagram for approximating the amount of deflection due to rotational force, FIG. 8 is a diagram showing the relationship between rotational force and amount of deflection, FIG. 9 is a diagram showing the arrangement of gears in the developing device, and FIG. is there. 1,21 toner supply section, 2,28 regulating member, 3,22 developing sleeve, 4,27 electrostatic latent image carrier, 6, toner
7: developing sleeve gear, 8, 32: intermediate gear.

Claims (2)

(57) [Claims] (A) an electrostatic latent image carrier for carrying an electrostatic latent image; and (b) an opposing electrostatic latent image carrier and rotatably fixed by two bearings. And a rotatable developing sleeve which is rotated by receiving a rotational force on an end side of the bearing and conveys the charged toner to the developing area; and (c) a surface of the developing sleeve upstream of the developing area. A regulating member disposed in contact with the regulating member and regulating a toner supply amount; and (d) a toner supplying portion disposed upstream of the regulating member and supplying the toner to the surface of the developing sleeve. (E) the direction of the rotational force applied to the developing sleeve;
An angle between a rotation center of the electrostatic latent image carrier and a line connecting the rotation center of the developing sleeve is set within a range of 0 to 110, 250 to 360 [゜]. 2. The developing sleeve according to claim 1, wherein the shaft diameter is d [mm], and the distance between two bearings supporting the developing sleeve is l.
[Mm], and when the component of the force applied to the axis of the developing sleeve in the direction connecting the rotation center of the electrostatic latent image carrier and the rotation center of the developing sleeve is Px (kg weight), P _X (l / d ²⁾ An apparatus according to claim 1 having a relationship of ² ≦ 100.