JPH09166915A - Thin film member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a satisfactory press-contact pressure between a developing roller and a blade, to uniformly and electrostatically charge toner and to make a thin layer uniform and to supply toner to an electrostatic latent image while keeping stable and moderately light contact with an electrostatic latent image carrier, by making the Young's modulus, the thickness and the radius of a thin film member satisfy a specified expression together. SOLUTION: The thin film member 11 is constituted of a cylindrical film with a circumferential length little longer than the outer circumferential length of the developing roller 10, and when the developing roller is armored by the member 11, a slight looseness is formed. And, as for the Young's modulus E (kg/mm<2> ) of the thin film member 11, the thickness (t) (mm) and the radius R (mm), 0.05<=Et<3> <=10 and also 2.5<=R<=50 are satisfied. In the case where the value of Et<3> is <0.05, a desired pressing force is not obtained within the size of the practical developing roller 10, on the other hand, in the case the value of Et<3> is >10, conversely, a pressing force against the photoreceptor is too strong within the extent of the practical developing roller 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film member used in a developing device such as an electrophotographic copying machine and a printer. More specifically, the present invention is a thin film member capable of making a light contact with a latent image formed on the surface of an electrostatic latent image carrier of a copying machine or the like to stably supply a uniform thin charged layer of toner. Regarding

[0002]

2. Description of the Related Art In order to create an image by using an electrophotographic system such as an electrophotographic copying machine, first, an electrostatic latent image is formed on the surface of a photoconductor which is an image carrier. Next, a developing device supplies charged toner to the surface of the photoconductor having the electrostatic latent image to develop (visualize) the toner image, and the obtained toner image is transferred and fixed on a transfer material such as paper. In a developing device used in such an electrophotographic copying machine, particularly a developing device using a non-magnetic toner as a one-component developer, it is important to supply a uniform thin layer of charged toner to the surface of the photoconductor.

Conventionally, as such a developing device, a non-magnetic toner is supplied to the surface of an elastic developing roller, and a blade is pressed against this to form a thin layer of charged toner on the outer peripheral surface of the roller, and the thin layer of charged toner is exposed to light. It has been proposed to form a toner image by bringing it into direct contact with the surface of the body (JP-A-52-143831).

However, in order to form the thin layer of charged toner, the blade must be brought into contact with the roller surface with a certain pressure contact force, and therefore the developing roller is required to have a relatively high hardness. On the other hand, the hardness of the developing roller is preferably as low as possible at the contact portion between the developing roller and the photosensitive member in order to prevent damage to the photosensitive member and destruction of the image.

From this point of view, a conductive thin film is provided on the surface of a roller made of a foamable soft conductive elastic material, and a toner is electrically attached to the surface by using a magnetic brush, and the roller and the photosensitive material are exposed. There has also been proposed a device in which toner is attached to an electrostatic latent image by contact with the body surface to develop the electrostatic latent image (JP-A-55-77764).

[0006]

However, even in the developing roller using such a foam material, it is not possible to sufficiently reduce the pressure contact force to the photoconductor, and in particular, the roller surface and the photoconductor surface. If there is a difference in peripheral speed between the image and the image, there is a problem that destructive development occurs in the image on the photoconductor.
That is, when the pressing force of the developing roller is increased, the force in the rotational direction of the sleeve due to the speed difference causes image damage (breaking), and the background fog becomes severe. On the other hand, if the pressing force is set too weak, it is not practically suitable because uniform and stable contact at the Nip is impossible over the width direction of the photoconductor surface.

An object of the present invention is to solve such a problem and to secure a sufficient pressure contact pressure between the developing roller and the blade in the toner supply section to ensure the charging of the toner and the uniformization of the thin layer. While improving, at the portion facing the electrostatic latent image carrier (photosensitive drum), the toner is supplied to the electrostatic latent image while maintaining a stable and moderately light contact with the electrostatic latent image carrier. .

[0008]

According to the present invention, there is provided a developing roller which is rotationally driven; a developing roller which has a slight excess peripheral length with respect to the peripheral length of the developing roller and is substantially covered with the developing roller. A cylindrical thin film member without slippage; a thin film contact means for closely contacting the thin film member on the side of the developing roller that is substantially opposite to the surface facing the photoconductor, and adhering an excessive portion of the thin film member to the photoconductor; A thin film member for use in a developing device comprising a thin layer forming means for forming a thin layer of charged toner on the outer surface of a thin film member adhered to the thin film member, wherein the longitudinal elastic modulus E (kg /
mm ² ), the thickness t (mm) and the radius R (mm) together satisfy the following formula: 0.05 ≦ Et ³ ≦ 10 2.5 ≦ R ≦ 50 is there.

Next, the results of tests conducted by applying the thin film member of the present invention to a developing device will be shown. Figure 3 shows nylon (film thickness;
●: 0.1, ▲: 0.2, ■: 0.3 mm), stainless steel
(Film thickness; □: 0.02, △: 0.03, ◯: 0.05mm)
The relationship between the radius R (mm) of the Et ³ and the pressing force (g / mm) when it was packaged in the developing roller was determined for each of the ³ materials.

In the present invention, when the value of Et ³ is smaller than 0.05, the range of the size of the developing roller is practical (radius 2.5 to 5).
0mm) does not give the required pressing force, while E
Contrary to t ³ being larger than 10, the pressing force against the photosensitive member is too strong in the range of the practical developing roller radius.

After all, as is apparent from FIG. 3, at a practical developing roller radius of 2.5 to 50 mm, the proper pressing force is within the range of Et ³ from 0.05 to 10 regardless of the kind and thickness of the material. A pressure of 0.2-1 g / mm is obtained.

The longitudinal elastic modulus (E kg / mm ² ) of a typical thin film member that can be used in the present invention is listed below.

Polyester 230 Polypropylene 120-170 Nylon 300-350 ETFE 150 Phenolic resin 800 Phosphor bronze 12200 Steel 21000 Spring steel 21500 Nickel 20900 The thin film member of the present invention having a specific Et ³ value and R value is coated on the developing roller. By appropriately setting the R value, it is possible to contact the photoconductor with an appropriate pressing force while maintaining the space with the developing roller.

[0014]

EXAMPLES Next, a developing device using the thin film member of the present invention will be described in more detail by way of examples with reference to the accompanying drawings.

FIG. 1 is a developing device using the thin film member of the present invention.
It is sectional drawing which shows (1). The developing device (1) is arranged adjacent to the photosensitive drum (100) which is rotationally driven in the direction of arrow (a). The developing device (1) includes a developing roller (10) forming a rotating body,
A cylindrical thin film member (11) externally mounted on the developing roller, a guide member (9), a pressure contact blade (12) pressed against the outer surface of the thin film member, and a toner for supporting and storing these.
It consists of a casing (3) that stores (To).

First, a developing roller (10) which is a toner carrier.
Is manufactured by a conductive member such as blasted and roughened aluminum, or aluminum having a conductive elastic rubber or a plastic layer on the surface,
A developing bias voltage is applied.

The thin film member (11) of the present invention comprises a developing roller (10).
It is made of a tubular film having a perimeter slightly longer than the perimeter of the, and is covered with the developing roller (10) to form a slight slack. The material of the thin film member may be any material such as a soft resin sheet, a sheet obtained by adding carbon or metal fine powder or the like to a resin, a metal thin film such as nickel or aluminum, and a sheet obtained by laminating the resin sheet and the metal thin film. But the modulus of elasticity E, thickness t and radius R
As described above, 0.05 ≦ Et ³ ≦ 10, 2.5 ≦ R ≦ 5
It is necessary to fill 0 together.

As shown in FIG. 2, the guide member (9), which is a means for closely contacting the thin film, has a developing roller (1) which is covered with the thin film member.
0) is provided at both ends and has an arcuate inner surface substantially corresponding to the outer surface shape of the developing roller.

Therefore, the guide member (9) brings the thin film member (11) into close contact with the periphery of the developing roller (10), so that the thin film member (11) is provided in the opening of the guide member provided on the surface facing the photosensitive drum. ) Is concentrated to form a constant space (S).

The arc of the inner surface of the guide member may be formed substantially as an arc, and even if the guide member is partially discontinuous, the elastic composite sheet such as polyurethane foam and polyester sheet is attached to the inner surface. Any shape may be used as long as the upper thin film member can be brought into close contact with the developing roller.

The thin film adhering means is an arc-shaped guide member for adhering the thin film member to the developing roller as shown in FIGS. 1 and 2, or a magnet for attracting the thin film member containing a magnetic material to the surface of the developing roller. In addition, any form may be used as long as the developing roller and the thin film member are brought into close contact with each other and an excess portion of the thin film member is generated at a portion facing the photoconductor. FIG. 2 is a perspective view showing a state where the developing roller (10) is assembled to the casing (3). As shown in FIG. 3, the thin film member
The developing roller (10) equipped with (11) has a support shaft (10a) rotatably supported by a side plate (4) of a casing (3) and is connected to a drive source (not shown). Both ends of the developing roller (10) are located in the recesses (8) formed in the side plate (4), and in the recesses (8),
A guide member (9) is attached so that the thin film member (11) is in close contact with the outer peripheral surface of the developing roller (10).

The outer peripheral surface of the developing roller (10) and the thin film member
If the friction coefficient between the inner peripheral surface of (11) is μ ₁ and the friction coefficient between the outer peripheral surface of the thin film member (11) and the guide member (9) is μ ₂ , μ ₁ >>
The relationship of μ ₂ is given, and the developing roller (10) shows an arrow.
When rotating in the (b) direction, the thin film member (11) also moves in the same direction without causing substantial slippage.

Further, a pressure welding blade which is a thin film forming member.
Teflon sheet is attached to the tip of (12), and the development roller (1
It is attached to the back side of the support member (6) provided on the upper part of (0). The blade (12) presses the thin film member (11) to the developing roller at an obliquely upper portion on the back side of the developing roller (10). As the thin film forming member, any conventionally known means such as a pressure contact roller can be used in addition to the pressure contact blade. Further, the toner leveling pad (1) is provided at a portion of the casing (3) facing the developing roller (10).
6) is attached. The toner leveling pad (16) presses the surface of the thin film member (11) toward the outer peripheral surface of the developing roller (10).

The casing (3) is provided with a toner storage tank (15). The toner storage tank (15) is provided with an agitator (14) which rotates in the direction of the arrow (c), and the toner stored inside is agitated.
It is moved in the direction of arrow (c) while preventing (To) blocking.

Next, the operation of developing with the developing apparatus using the thin film member of the present invention will be described with reference to FIG.

The developing roller (10) and the agitator (14) are
A drive source (not shown) rotates in the directions of arrows (b) and (c), and the toner (To) is forcibly moved in the direction of arrow (c). On the other hand, the thin film member (11) is the developing roller (10).
Due to the frictional force with the developing roller (10), the developing roller (10) is rotated in the direction of the arrow (b). The toner (To) in the toner storage tank (15) adheres to the surface of the thin film member (11) by contact with the thin film member (11) and electrostatic force, and is conveyed in the direction of arrow (b). Toner (To)
Is taken into the wedge-shaped portion (13) formed by the thin film member (11) and the tip of the blade (12), the blade (12)
Of the thin film member (11) is uniformly applied to the surface of the thin film member (11) in the form of a thin layer and frictionally charged to a predetermined positive or negative polarity.

The thin layer toner (To) held on the thin film member (11) by the electrostatic force due to its own charging further moves to the portion (developing area (X)) facing the photosensitive drum (100). Carried
An electric field based on the voltage difference between the surface potential of the photoconductor drum (100) and the bias voltage applied to the developing roller (10) moves to the electrostatic latent image formed on the surface of the photoconductor drum (100). To form a toner image.

The thin film member (11) in contact with the photosensitive drum (100) has a space (S) between it and the developing roller (10) and is not in contact with the developing roller. Therefore, the thin film member (11) softly contacts the photosensitive drum (100) only with its own proper steel satisfying the predetermined condition, and evenly contacts the photosensitive drum (100) at an appropriate nip width, and A uniform toner image is formed on the electrostatic latent image. Further, it is effective to remove background fog by providing a speed difference between the peripheral speed of the photoconductor drum (100) and the speed of the thin film member (11), and once formed on the photoconductor drum (100). The formed toner image is not destroyed by the physical force such as the rubbing force of the thin film member.

Next, the toner (To) remaining on the thin film member (11) in the developing area (X) is continuously conveyed in the direction of the arrow (b) together with the thin film member (11), and the toner leveling pad (16). The toner (T) consumed in the developing area (X) when passing between
The consumption pattern of o) is erased and the surface residual toner layer is made uniform.

Further, the toner (To) is re-supplied to the surface of the thin film member (11) by the rotation of the agitator (14), a uniform charged toner thin layer is formed at the pressure contact portion of the blade (12), and the above-mentioned toner is again formed. Repeat the operation of.

Next, the results of developing a developing device using various thin film members will be shown.

Test Example 1 As a thin film member, a Ni electroformed thin film (E: 2.1 × 10 ⁴ kg
/ Mm ² , film thickness t: 40μ, Et ³ = 1.34, width b: 2
20 mm) was used. This is surface roughened (average roughness 5μ
R _Z ) to form a thin film cylinder (inner diameter 25 mmφ), drive roller
(Surface conductive rubber coat layer, outer diameter 24.5 mmφ, rubber hardness 40 °) was externally inserted and used as a developing sleeve. Silicon rubber blade (thickness 1.6
mm, hardness 50 °) and charged toner layer on thin film member
(0.5 mg / cm ² , thickness 20 μ, charge amount +20 μq /
g) was formed. The toner used was a positive polarity toner (styrene acrylic resin, average particle size 13 μ). Vi = -400V was applied as the electrostatic latent image on the photosensitive drum, and -200V was applied to the thin film member as the developing bias. The Talumi part of the thin film member is set at the position facing the surface of the photoconductor drum, and the pushing amount (δ) of the Talmi part of the thin film member to the photoconductor is 0.5 mm.
As contacted. With this setting, the thin film member was rotated and contact development was performed on the surface of the photoconductor at the moving speed of the thin film member / surface speed of the photoconductor drum = 3/1. A sufficient developed image (ID = 1.3) was obtained without any deterioration.

Assuming that the load on the photosensitive member is W and the thin film member on the developing sleeve is a support beam (fixed end) at both ends, W = 384 Ebt ³ δ / 12 (πr) ³ = 83.204 (g) ) Is the calculated value of the pressing force per unit length 0.378g
/ Mm is obtained, and it is estimated that an appropriate pressing force of 0.2 to 1 g / mm is generated.

Test Example 2 As a thin film member, a nylon extrusion molding tube (E:
0.03 × 10 ⁴ kg / mm ² , film thickness 180 μ, Et ³ = 1.7
4, width: 220 mm, inner diameter 25 mmφ), and contact development was performed under the same conditions as in Test Example 1. The nylon tube contained carbon particles and imparted conductivity, and had an average surface resistance of 10 ⁴ Ωcm. When contact development was performed at a speed difference of θ = 3 in the same manner as described above, a sufficiently satisfactory developed image was obtained as with the Ni electroformed thin film. The calculated value W from the double-ended free beam model was 108.314 g, which was 0.49 g / mm.

Comparative Test Example 1 Contact development was carried out under the same conditions except that the same nylon extrusion molding tube as in Test Example 2 (thickness 350 μm, Et ³ = 12.86) was used as the thin film member. Speed difference θ =
When contact development was carried out in No. 3, the pressing force on the contact surface was too large, the background fogging was severe, and the reproduced image was deteriorated due to the scratch due to the speed difference of the contact surface, and the horizontal thin line was hardly reproduced. At this time, the calculated value of W was 796.29 g, and the pressing force per unit length was 3.61 g / mm.

Test Comparative Example 2 Nylon extrusion molding tube (film thickness 350 μ, Et ³ =
12.86, inner diameter 60mmφ) was manufactured and the drive roller 59
It was packaged in mmφ. When contact development was performed with the above materials and conditions at a speed difference of θ = 3, the pressing force was appropriate, but the developing device was large and not practically preferable. At this time, the calculated value was W = 56.8 g, and the pressing force per unit length was 0.25 g.

[0037]

According to the developing device using the thin film member of the present invention, since the thin film member is in close contact with the developing roller in the toner supply section, a sufficient pressure contact force is secured for the toner thin layer regulation by the blade. As a result, the charge of the toner can be improved to a desired value, and the toner can be uniformly thinned. On the other hand, in the developing area, the thin film member can make stable and accurate contact with the photosensitive drum with an appropriate low pressure contact force, and supplies the toner uniformly to the electrostatic latent image so that there is no density unevenness. It is possible to form an image having a reduced density.

[Brief description of the drawings]

FIG. 1 is a sectional view of a developing device using a thin film member of the present invention.

FIG. 2 is a perspective view showing a supporting state of a developing roller using the thin film member of the present invention.

FIG. 3 is a graph showing the relationship between R and pressing force for various Et ³ values.

[Explanation of symbols]

 1 Developing Device 3 Casing 9 Guide Member 10 Developing Roller 11 Thin Film Member 12 Pressing Blade

Claims (1)

[Claims] 1. A developing roller that is rotationally driven; a cylindrical thin film that has a slight excess peripheral length with respect to the peripheral length of the developing roller, is covered by the developing roller, and is substantially non-slip with the developing roller. A member; a thin film contact means for closely contacting the thin film member on a side of the developing roller opposite to a surface of the developing roller facing the photoreceptor, and an excessive portion of the thin film member for adhesion to the photoreceptor; and an outer surface of the thin film member adhered to the developing roller. A thin film member used in a developing device comprising a thin layer forming means for forming a thin layer of charged toner, having a longitudinal elastic modulus E (kg / mm ² ), a thickness t (mm) and a radius R (mm) as follows. A thin film member that satisfies both formulas. 0.05 ≦ Et ³ ≦ 10 2.5 ≦ R ≦ 50