JPH1138846A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove residual particles smoothly even when a cleaning blade has a thickness error somewhat by setting the mutual relation between the press-contact angle of the blade with an electrostatic latent image carrier and the bent amount of the corner part of the free end of the blade so that a holding member may not come in contact with a photoreceptor at the specified press- contact angle. SOLUTION: The corner part S of the free end of the cleaning blade 71 continuous to a surface C toward the photoreceptor drum 1 press-contacts with the drum 1 by the spring force of a press-contact spring 73. Then, the radius R of the surface part of the drum 1 with which the corner part S of the free end of the blade 71 press-contacts, the thickness T of the end of a blade holding member 72 near to the corner part S, the free end length L of the blade 71 from the holding member 72 to the corner part S and the bent amount U caused by the press-contact of the corner part S with the drum 1 are relatively set so that the holding member 72 is not in contact with the drum 1 until the press- contact angle θ of the blade 71 with the drum 1 reaches a predetermined allowable minimum press-contact angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art Electrophotographic copying machines, facsimile machines,
In an image forming apparatus such as a printer, generally, an electrostatic latent image carrier such as a photoconductor is charged, and an electrostatic latent image is formed by exposing the charged area to an image based on image information. The latent image is developed using a developer containing colored particles (toner) to form a visible image, and this visible image is primarily transferred to an intermediate transfer member, and further secondary transferred to a recording material such as paper. Alternatively, the image is directly transferred to a recording material and fixed. After transferring the visible image composed of the colored particles to the transfer target such as the intermediate transfer member or the recording material, the remaining particles that have not been transferred remain on the electrostatic latent image carrier. To remove this, a cleaning device is employed.

A cleaning member of this type is provided with a cleaning member for removing the residual particles.
The cleaning member includes a contact type and a non-contact type. A cleaning blade is often used for the contact-type cleaning member. As a material of the cleaning blade, an elastic material such as an elastic body is employed. This is because the cleaning blade is brought into contact with the electrostatic latent image carrier at a predetermined angle, and is elastically pressed while allowing the electrostatic latent image carrier to bend so that residual particles can be reliably removed. To do that.

However, such a cleaning device has the following disadvantages. In manufacturing the cleaning blade, an error is inevitably caused in the thickness of the cleaning blade. For example, when a cleaning blade having a thickness of 2 mm is manufactured, the thickness may be about 2 ± 0.2 mm. In this case, a cleaning blade having an error of about 10% is manufactured. This thickness error of the cleaning blade is an obstacle to securing the pressure contact accuracy for the cleaning blade that requires pressure contact accuracy with the electrostatic latent image carrier. That is, even if the magnitude of the force applied to the cleaning blade is the same, the manner of bending of the cleaning blade differs due to the thickness error of the cleaning blade, and the state of contact with the electrostatic latent image carrier (contact nip width, etc.) is reduced. In other words, the cleaning performance is not uniform among the cleaning blades, and in some cases, the cleaning performance is reduced, resulting in an image defect.

Therefore, in order to eliminate the adverse effects caused by such a thickness error of the cleaning blade, the free edge of the cleaning blade on the extension of the holding surface of the cleaning blade to the cleaning blade holding member that supports the cleaning blade in a cantilever manner. A configuration has been proposed in which the cleaning unit is configured to abut on an electrostatic latent image carrier. With this configuration, even if a thickness error occurs in the cleaning blade, the cleaning surface is not affected, so that the cleaning performance is substantially uniform, and desired cleaning performance is achieved.

[0006]

However, when such a cleaning blade is employed, the cleaning blade holding member is disposed close to the electrostatic latent image carrier, and the holding member has A spring force is always applied in a direction in which the cleaning blade is pressed against the electrostatic latent image carrier, and these cause the following problems.

That is, when the material of the cleaning blade has a large permanent elongation or permanent strain, the cleaning blade is used for a long time in a state in which the cleaning blade is pressed against the electrostatic latent image carrier, so that the amount of bending of the cleaning blade increases. And / or in a high-temperature and high-humidity environment, by leaving the cleaning blade for a long time, the hardness of the cleaning blade decreases, the cleaning blade becomes softer, and the amount of deflection of the cleaning blade increases. There is a problem that the electrostatic latent image carrier moves and comes into contact with the electrostatic latent image carrier. In particular, when the radius of curvature of the surface portion of the electrostatic latent image carrier to which the cleaning blade is pressed is large, the initial gap distance between the holding member and the image carrier becomes small, and this problem becomes remarkable. .

In the present invention, an electrostatic latent image formed on an electrostatic latent image carrier having a moving surface is developed using a developer containing colored particles, and the resulting visible image is transferred. An image forming apparatus that transfers the toner particles to a body, and scrapes residual particles remaining on the electrostatic latent image carrier without being transferred by a cleaning blade pressed against the electrostatic latent image carrier. Even if there is a slight thickness error, there is no problem in removing the residual particles, and even if the cleaning blade is used for a long time in a state of being pressed against the electrostatic latent image carrier, or in a high temperature and high humidity environment. Even if the cleaning blade is left for a long time, the cleaning blade holding member contacts the electrostatic latent image carrier regardless of the magnitude of the radius of curvature of the surface portion of the electrostatic latent image carrier against which the cleaning blade is pressed. No risk of erosion is, or it is an object to provide an extremely small image forming apparatus.

[0009]

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention is a developer for forming an electrostatic latent image formed on an electrostatic latent image carrier having a moving surface, the developer containing colored particles. Developed using, and the obtained visible image is transferred to an object to be transferred,
An image forming apparatus that scrapes residual particles remaining on the electrostatic latent image carrier without being transferred by a cleaning device, wherein the cleaning device includes a cleaning blade, and a cleaning blade holding member that supports the cleaning blade in a cantilever manner. The cleaning blade is pressed against the surface of the electrostatic latent image carrier at a free edge corner following a surface facing the electrostatic latent image carrier, and the cleaning blade holding member is At least a part thereof is cantilevered at an end opposite to the free edge corner of the cleaning blade in a state of being disposed between the cleaning blade and the electrostatic latent image carrier, The cleaning blade is provided so as to be rotatable about a fulcrum at a fixed position, and a spring is provided in a direction in which the free edge of the cleaning blade is pressed against the surface of the electrostatic latent image carrier. Wherein the cleaning blade free edge corner is pressed against the radius of curvature of the surface portion of the electrostatic latent image carrier, and the cleaning blade holding member faces the electrostatic latent image carrier. Thickness of the edge near the cleaning blade free edge corner, free edge length of the cleaning blade from the cleaning blade holding member to the cleaning blade free edge corner,
The correlation between the pressure contact angle of the cleaning blade to the electrostatic latent image carrier and the amount of deflection of the free edge of the cleaning blade at the pressure contact angle is from the value at which the pressure contact angle is greater than 0 ° to 0 °. The cleaning blade holding member is set so as not to come into contact with the electrostatic latent image carrier until it reaches (before contacting with the so-called belly contact state).

The pressure contact angle of the cleaning blade with respect to the electrostatic latent image carrier is, as shown in FIG. 1, the free edge of the cleaning blade B being pressed against the electrostatic latent image carrier PC. Of the angle between the tangent line a drawn on the electrostatic latent image carrier and the tangent line b drawn on the blade at the contact portion between them, the angle on the downstream side in the electrostatic latent image carrier surface movement direction X θ.

The cleaning blade holding member may be configured such that the end of the cleaning blade holding member, which faces the electrostatic latent image carrier, is closer to the corner of the free edge of the cleaning blade than the portion adjacent to the end. Good. Thereby, the risk of contact between the cleaning blade holding member and the electrostatic latent image carrier is further reduced. A radius of curvature R of a surface portion of the electrostatic latent image carrier on which a corner of the cleaning blade free edge is pressed; a free edge of the cleaning blade facing the electrostatic latent image carrier of the cleaning blade holding member; The thickness T of the end near the corner, the free end length L of the cleaning blade from the cleaning blade holding member to the corner of the free edge of the cleaning blade, a predetermined length of the cleaning blade to the electrostatic latent image carrier. interrelationship of deflection of U of said cleaning blade free edge corner of the allowable minimum pressure angle theta _m and piezoelectric contact angle theta _m, for example, the latent electrostatic image, wherein the cleaning blade free edge angle portion is pressed against If carrier surface portion of the curved _{surface, R + U - (2LTcosθ m} -3UTsinθ m) / √ (4L 2 + 9U 2)> √ (R 2 -L 2) ... so as to satisfy the condition of equation (1), the cleaning Bed When the latent electrostatic image bearing member surface portion over de free end edge corner portion is pressed against the plane, U - the _{(2LTcosθ m -3UTsinθ m) / √} (4L 2 + 9U 2)> 0 ... Equation (2) It is good to set so as to satisfy the condition.

The initial pressure contact angle of the cleaning blade with respect to the electrostatic latent image carrier is not limited thereto, but is usually about 10 ° to 20 ° from the viewpoint of miniaturization and compactness of the image forming apparatus. Set. Therefore, the acceptable minimum pressure angle theta _m to set the expression, 0 ° may be, but is set to about 15 ° or less 5 ° or more depending on the initial pressure angle, it is appropriate to set the other parameters is there.
The pressure angle theta _m becomes wasteful too for safety when too large, too small a risk that the blade holding member contacts the electrostatic latent image bearing member increases.

[0013] In this case, the cleaning blade holding member may have a thickness near the corner of the free edge of the cleaning blade, which faces the electrostatic latent image carrier, as compared with a portion adjacent to the edge. It may be thin. Next, the expressions (1) and (2) will be described with reference to FIGS.

FIG. 1 is a diagram showing an example of a contact relationship between a cleaning device and an electrostatic latent image carrier in an image forming apparatus. FIG. 2 is a diagram showing contact between the cleaning blade and the electrostatic latent image carrier shown in FIG. It is an enlarged view of a part and its peripheral part. FIG. 1 shows an electrostatic latent image carrier PC and a cleaning blade B.
Further, a cleaning blade holding member H is shown.

The electrostatic latent image carrier PC has a drum shape here, and its surface moves in the X direction. The electrostatic latent image carrier PC, the cleaning blade B, and the cleaning blade holding member H all extend in a direction crossing the surface movement direction X of the electrostatic latent image carrier PC. The cleaning blade B is pressed against the surface of the electrostatic latent image carrier PC at a free edge corner S following the surface C facing the electrostatic latent image carrier PC.

The cleaning blade holding member H is on the opposite side to the free edge corner S of the cleaning blade B in a state where at least a part H1 thereof is disposed between the cleaning blade B and the electrostatic latent image carrier PC. A direction D in which the cleaning blade free end edge S is pressed against the surface of the electrostatic latent image carrier PC. Is provided with a spring force. In the illustrated example, the spring force is applied to a portion H2 bent and continuous with the portion H1 supporting the blade B.

Here, as shown in FIG. 2, the electrostatic latent image carrier PC against which the cleaning blade free edge corner S is pressed.
The radius of curvature of the surface portion (here, the radius of the image carrier from the rotation center O of the image carrier PC to the surface of the image carrier) is R, and the cleaning blade holding member H (particularly the blade holding portion H
1) the thickness T, the free end length of the cleaning blade B from the cleaning blade holding member H to the cleaning blade free edge corner S, and the electrostatic latent image carrier PC of the cleaning blade free edge corner S. The amount of deflection of the blade due to pressure contact with U is denoted by U, and the pressure contact angle of the cleaning blade B against the electrostatic latent image carrier PC, that is, the angle between the tangent line a and the tangent line b as described above, Carrier PC
In the surface movement direction X, the angle on the downstream side is θ.

The bending amount U is, in other words, a virtual bite amount into the image carrier, and a straight line drawn between the fulcrum A and the free edge corner S in FIG. Assuming that a straight line drawn along the surface of the portion S1 facing the image carrier PC is e, a straight line orthogonal to the straight line e and drawn at the free edge corner S is w, and the intersection of the straight line w and the straight line e is W. , The distance between the point W and the free edge corner S.

Assuming that the pressure contact angle when the cleaning blade B is not bent is Φ ₀ , the pressure contact angle Φ ₀ is
The angle formed by the tangent line a and the straight line d above the free edge corner S in the figure. The intersection of the tangent a and the straight line e is V,
Assuming that the intersection point between the tangent line b and the straight line e is M, the angle of the angle between the tangent line a and the straight line e above the point V in the figure is Φ ₁ , and the angle between the tangent line b and the straight line e below the point M in the figure. Is Φ ₂ , and the angle between the fulcrum A and the lower side of the angle formed by the straight line d and the straight line e is Φ ₃ . The angle [Phi ₂ is a deflection angle of the cleaning blade B.

From the figure, the angle Φ ₁ is the angle Φ ₀ and the angle Φ ₃
Φ ₁ = Φ ₀ + Φ ₃ (3) Since the angle Φ ₁ is equal to the sum of the angle θ and the angle Φ ₂ , the formula Φ ₁ = θ + Φ ₂ (4) From equation (4), Φ ₀ + Φ ₃ = θ + Φ ₂ ∴θ = Φ ₀ −Φ ₂ + Φ ₃ Equation (5) Assuming that the distance between the fulcrum A and the point W is d1, the angle Φ ₃ is Φ ₃ = tan ^-1 (U / d1) Expression (6).

The cleaning blade B can be regarded as a cantilever having a load applied to the free end, and the cleaning blade B is subjected to a load f per unit width of the free end of the blade applied by being pressed against the image carrier PC. amount of deflection, can be viewed as a state that is deflected by the deflection angle of [Phi _2. This is illustrated in FIG. Accordingly, the amount of deflection U = fL ³ / 3EJ (7) The deflection angle Φ ₂ = tan ^-1 (fL ² / 2EJ) (8) where E is the Young's modulus of the blade, and J is the section 2 of the blade. is the next moment, looking at the per blade unit width, J = t ^3/12 (however, t is the blade thickness of) is. The J = t ^3/12 Equation (7), is substituted into Equation ^{(8), U = 4fL 3} / Et 3 ... Equation (9) Φ ₂ = tan ^-1 [(3 / 2L) × (4fL 3 / Et ³ )] Equation (10) When Equation (9) is substituted into Equation (10), Φ ₂ = tan ^-1 (3U / 2L) Equation (11) Equation (6) and Equation (11) are converted into Equation (5). ), Θ = Φ ₀ −tan ⁻¹ (3U / 2L) + tan ⁻¹ (U / d1) Expression (12) The pressure contact angle θ is 0 °, that is, the blade B is the image carrier PC.
Considering the state when the contact of the cleaning blade B with the so-called belly is started, from equation (4) and equation (11), Φ ₁ = tan ^-1 (3U / 2L) equation (13) Will be described with reference to FIG.

FIG. 4 shows the cleaning blade B shown in FIG.
FIG. 5 is a diagram showing a state in which the bending direction of a is viewed as an arc. The cleaning blade B is cantilevered at a point P by a cleaning blade holding member H. In FIG. 4, a free end Z0 of the cleaning blade B indicates a free end in a state where the cleaning blade B is not bent. The free end Z is a free end when the amount of bending of the cleaning blade B is U. Z1 indicates a state where the free end Z is further bent.

The straight line perpendicular to the blade B when it is not bent and drawn at the point P is denoted by g, the corners of the free ends Z and Z1 at the free edge are denoted by points S and S1, respectively, and drawn at the free end Z at the point S. Let h be a straight line orthogonal to the tangent z, and the free end Z at the point S1.
Assuming that a straight line orthogonal to the tangent line z1 drawn at 1 is h1, intersections of the straight lines h and h1 with the straight line g are points N and N1 respectively.
Becomes

The distance between point P and point N is r, the distance between point P and point N1 is r1, the angle between line g and line h is δ, and the angle between line g and line h1 is δ1. Then, the free end Z state blade can be regarded as an arc having a center r and a radius r and a center angle δ, and the free end Z1 state blade is an arc having a center r1 and a radius r1 and a center angle δ1. Can be seen.

The amount of deflection U of the free end Z can be expressed as follows from the figure. U = r−r COSδ Expression (14) Here, returning to FIG. 2 again, FIG. 2 shows the straight line g, h point P, N, center angle δ, radius r, etc. described with reference to FIG. Are also shown. However, these in FIG.
Are assumed to be in a state in which they have come into contact with the image carrier PC on the antinode, that is, a state in which the pressure contact angle θ has been reduced to 0 °, more specifically, a state in which the tangent lines a and b coincide with each other.

That is, let P be the point at which the cleaning blade B is cantilevered by the cleaning blade holding member H. Assuming that a line perpendicular to the line e and drawn from the point P is g, and a line drawn between the free edge corner S and the point O (center of the image carrier) is h, the intersection of the line g and the line h is the point N Become. The distance between the point N and the point S is represented by r, and the angle between the straight line g and the straight line h is represented by δ.
Can be regarded as an arc having a radius r with the center at the point N and a center angle δ.

Here, the tangent line a and the straight line h and the straight line e
And the line g are orthogonal, the angle δ between the line h and the line g is equal to the angle Φ ₁ between the tangent a and the line e, and Φ ₁
= Δ. Substituting this into Expression (13), δ = tan ⁻¹ (3U / 2L) Expression (15) If x = 3U / 2L, Expression (15) is expressed as follows: δ = tan ⁻¹ x Expression (16) Using the trigonometric function formula, transforming equation (16) gives: δ = cos ^-1 [1 / √ (x ² +1)] Equation (17) When the inverse trigonometric function of equation (17) is restored, , Cos δ = 1 / √ (x ² +1) Expression (18) Next, taking the pressure contact angle into account, substituting Expression (11) into Expression (4), Φ ₁ = tan ⁻¹ (3U / 2L) + θ Equation (19) When Φ ₁ = δ and x = 3U / 2L are substituted into Equation (19), δ = tan ⁻¹ x + θ Equation (20) An equation is obtained in the same manner as Equations (16) and (18). (20) can be solved as follows. By transforming equation (20) using the trigonometric function formula, δ = cos ⁻¹ [1 / √ (x ² +1)] + θ (Equation (21)) From equation (21), cos δ = cos [cos ⁻¹ [ 1 / √ (x ² +1)] + θ] = cos cos ^-1 [1 // (x ² +1)] cos θ-sin [cos ^-1 [1 // (x ² +1)] sin θ = cos θ / √ (x ² +1)-√ ｛1-cos ² cos ^-1 [1 // (x ² +1)]]｝ sin θ = cos θ / √ (x ² +1)-√ [x ² / (x ² +1)] sin θ ∴cos δ = (cos θ−x sin θ) / √ (x ² +1) Equation (22) In FIG. 2, the cleaning facing the electrostatic latent image carrier PC is performed. The cleaning blade holding member end from the blade free edge corner S is a point Q, and a straight line parallel to the straight line h and drawn at the point Q is k1, and an intersection between the straight line k1 and the surface of the electrostatic latent image carrier PC is a point K. And

Dotted lines parallel to the tangent line a and drawn at points P, Q, and K are defined as straight lines p, q, and k2, and intersections of the straight line h with the straight lines p, q, and k2 are defined as points Px, Qx, and Kx, respectively. The straight lines drawn at points O and K are y, the straight lines y and h
Is an angle α, an intersection of a straight line q parallel to the straight line h and drawn at the point P and a straight line q is Qy, and a triangle connecting the points N, P and Px is γ1 and a triangle connecting the points P, Q and Qy To γ2, point O,
A triangle connecting K and Kx is defined as γ3.

Here, assuming that the point O is the origin and the straight line h is the x coordinate, the distance between the point N and the point Px is represented by a triangle γ1.
Therefore, the x coordinate Px is given by: Px = R + (r−r cos δ) Equation (23) The distance between the point Px and the point Qx is represented by Tco
sδ, the x-coordinate Qx is calculated as follows: Qx = Px−T cos δ Equation (24) By substituting equation (23) into equation (24), Qx = R + (r−r cos δ) −T cos δ Expression (25) The x-coordinate Kx is represented by the following equation: Kx = R cos α = √ [R ^2- (R sin α) ² ] Expression (26) where the blade B touches the image carrier PC. Started to do
In order to prevent the blade holding member H from coming into contact with the image carrier PC even when the pressure contact angle θ becomes 0 °, the point Qx is set at a position on the left side of the surface of the image carrier PC.
And the point Kx satisfy the condition of Qx> Kx (27).

Substituting Equations (25) and (26) into Equation (27), R + (r-r cos δ)-T cos δ> √ [R ^2- (R sin α) ² ] ... Equation ( 28) If the free end length L is approximated to the distance L ′ between the point K and the point Kx, L ≒ L ′ (29) The distance L ′ is calculated by the triangle γ3 as L ′ = R sin α (Equation 29) 30) From Expressions (29) and (30), L ≒ R sin α ... Expression (31) Substituting Expression (31) into Expression (28), R + (r-r cos δ)-T cos δ> √ (R ² −L ² ) Expression (32) Substituting Expressions (14) and (22) into Expression (32), R + U−T [cos θ− (3U / 2L) sin θ] / √ [(9U ² / 4L ² ) +1]> √ (R ² -L ² ) Equation (33) By rearranging equation (33) and substituting the allowable minimum angle θ _m into θ, the following equation is obtained. (1) can be obtained.

[0031] _{R + U - (2LTcosθ m -3UTsinθ} m) / √ (4L 2 + 9U 2)> √ (R 2 -L 2) ... Equation (1) also an electrostatic latent cleaning blade free edge angle portion is pressed against Considering the case where the surface portion of the image carrier is flat, it may be assumed that the radius R of the electrostatic latent image carrier PC becomes infinite. That is, when R becomes extremely large, the right side of equation (1) can be calculated as {(R ² −L ² )} R. Therefore, in equation (1), R on both sides are canceled, and equation (2) can be obtained as in the following equation.

[0032] U - The _{(2LTcosθ m -3UTsinθ m) / √} (4L 2 + 9U 2)> 0 ... image forming apparatus so as to satisfy the condition of equation (2) above in the formula (1) or Formula (2) By setting, even if the cleaning blade is left for a long time in a state of being pressed against the electrostatic latent image carrier, or if the cleaning blade is left for a long time in a high temperature environment and the amount of bending of the cleaning blade increases, the static Regardless of the magnitude of the radius of curvature of the surface portion of the electrostatic latent image carrier, the cleaning blade holding member is less likely to come into contact with the electrostatic latent image carrier.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention, and FIG. 6 is an enlarged view of the cleaning device shown in FIG. The image forming apparatus shown in FIG. 5 includes a photosensitive drum 1 as an example of an electrostatic latent image carrier in the center, and a charging device 2, a split head 3, a developing device 4, a transfer device 5, and a separation device around the photosensitive drum 1. The device 6, the cleaning device 7, and the static eliminator 8 are arranged in that order.

The photosensitive drum 1 has a drum shape.
It is driven to rotate in the direction a in the figure. Charging device 2 is powered PW1
, A charging voltage can be applied to charge the surface of the photosensitive drum 1 uniformly. The transfer device 5 faces the photosensitive drum 1 and forms a transfer portion ST. A transfer voltage can be applied to the transfer device 5 from the power supply PW2. The separation device 6 is arranged to the left of the transfer device 5 in the drawing, and can apply an AC separation voltage from the power supply PW3.

On the right side of the transfer section ST, there are a conveyance guide 10 and a pair of timing rollers 9. A transport guide 11 is provided on the left side of the separation device 6, and a fixing device 12 is further provided on the left side thereof. In this image forming apparatus, a laser beam L emitted from the print head 3 based on image data forms an electrostatic latent image on the charged area on the photosensitive drum 1. This electrostatic latent image moves to the developing device 4 as the photosensitive drum 1 rotates.

The developing device 4 contains a developer D,
A developing roller 41, a supply roller 42, and a stirring roller 43 are provided. The developer D contains a toner (colored particles) and a carrier. The developing roller 41, the supply roller 42, and the stirring roller 43 are driven to rotate in the directions b, c, and d, respectively, in the drawing. The developing device may employ a one-component developer that does not use a carrier.

By the rotation of the stirring roller 43, the developer D containing the toner and the carrier is uniformly mixed. The developer D is sent to the supply roller 42, and further sent to the development roller 41 by the rotation of the supply roller 42. It is. The developer D adheres to the surface of the developing roller 41, moves to the electrostatic latent image developing area with its rotation, and is subjected to the development of the electrostatic latent image under the application of a developing bias voltage by the power supply PW4. The electrostatic latent image becomes a visible toner image.

The recording paper SH is sent out from a paper feed tray (not shown) by a paper feed roller (not shown) and sent to a timing roller pair 9. Timing roller pair 9
Sends out the recording paper SH in synchronization with the toner image on the photosensitive drum 1. The recording sheet SH is supported by the transport guide 10 and moves to the transfer section ST. Then, the toner image on the photosensitive drum 1 is transferred to the recording paper SH by the transfer device 5 to which the transfer voltage is applied from the power supply PW2. The recording paper SH onto which the toner image has been transferred is separated from the photoreceptor 1 by a separation device 6 to which an AC separation voltage is applied from a power source PW3, and is conveyed to a fixing device 12 along a conveyance guide 11, where the toner image is recorded. The image is fixed on the paper SH.

The photosensitive drum 1 continues to rotate even after the transfer of the toner image, and the residual toner that has not been transferred to the transfer paper SH on the photosensitive drum 1 moves to the cleaning device 7. The cleaning device 7 includes a cleaning blade 71, a cleaning blade holding member 72, a pressure spring 73, and a toner conveying screw 74, which are provided in a cleaning device case 700.

The photosensitive drum 1, the cleaning blade 71, the cleaning blade holding member 72, etc.
Each of them extends in a direction crossing the rotation direction of the photosensitive drum 1. The cleaning blade 71 is provided on the photosensitive drum 1
Is pressed against the surface of the photoreceptor drum 1 at a free edge corner S following the surface C facing the surface.

As shown in FIG. 5 and FIG. 6, the cleaning blade holding member 72 is a member bent in a "H" shape when viewed from the side, and a portion 721 having a thickness T before the bent portion is a cleaning blade. The cleaning blade 71 cantileverly supports an end S1 opposite to the free edge corner S of the cleaning blade 71 in a state where the cleaning blade 71 is disposed between the cleaning blade 71 and the photosensitive drum 1. , And is rotatable around the center (fulcrum) A of the shaft 720. A spring force is applied to a portion 722 behind the bent portion by a press-contact spring 73 in a direction B in the drawing so as to press the free edge corner S of the cleaning blade against the surface of the photosensitive drum 1. Note that the cleaning blade 71 is
Here, a spring is used as a means for pressing against, but the invention is not limited to this, and a spring or the like may be used. A force can be applied.

The toner conveying screw 74 is driven to rotate in the direction e in the figure. The residual toner on the photosensitive drum 1 is
When the cleaning blade 71 is pressed against the photosensitive drum 1, the cleaning blade 71 is scraped off by the rotation of the photosensitive drum 1 with the rotation of the photosensitive drum 1, and falls to the toner conveying screw 74, thus removing the residual toner on the photosensitive drum 1. The dropped residual toner moves with the rotation of the toner conveying screw 74 and is carried to a predetermined position outside the cleaning device. The photoreceptor drum 1 continues to rotate further, and the residual charges on the photoreceptor drum 1 are discharged by the discharger 8 to prepare for the next process.

According to this image forming apparatus, since the free edge corner S of the cleaning blade 71 of the cleaning device 7 is pressed against the surface of the photosensitive drum 1, even if there is some error in the thickness of the blade, There is no problem in removing the residual toner. Further, according to this image forming apparatus, as shown in FIG. 6, the radius of the surface portion of the photosensitive drum 1 against which the cleaning blade free edge corner S is pressed is R, and the blade free edge angle of the cleaning blade holding member 72 is R. The thickness of the end near the portion S is T, and the cleaning blade holding member 72
, The free end length of the cleaning blade 71 from the cleaning blade free edge edge S to the cleaning blade free edge corner S is L, and the amount of deflection of the cleaning blade free edge edge S by pressing against the photosensitive drum 1 is U. interrelationship of L and U, until pressure angle of the photosensitive drum 1 of the cleaning blade 71 reaches a predetermined allowable minimum pressure angle theta _m, as a cleaning blade holding member 72 does not contact the photosensitive drum 1 Is set.

The pressure contact angle of the cleaning blade 71 to the photosensitive drum 1 means that when the free edge S of the cleaning blade 71 is pressed to the photosensitive drum 1 as shown in FIG. Photoconductor drum 1 at the site
Is the angle .theta. On the downstream side in the surface movement direction a of the photosensitive drum 1 among the angles formed by the tangent line a drawn on the cleaning blade 71 and the tangent line b drawn on the cleaning blade 71.

As described above, the holding member 72 contacts the photosensitive member 1.
In order not to touch, here R, T, L and
U and predetermined allowable minimum pressure contact angle θ_mThe relationship of R + U− (2LTcosθ_m−3UTsinθ_m) / √ (4L^Two+ 9U^Two)> √ (R^Two−L^Two)… Set to satisfy the condition of equation (1). Satisfy this formula
To make the pressure contact angle θ _mThe holding member 72 is
Does not contact the photosensitive drum PC.

Although the initial pressure contact angle of the cleaning blade 71 to the photosensitive drum 1 is not limited thereto, it is usually set to about 10 ° to 20 °. Therefore, the above equation (1)
In, the pressure angle theta _m to set, is the extent set to 15 ° 5 ° or less, depending on the initial pressure angle, the other parameters so as to satisfy equation (1) in response thereto is set.

Although not limited thereto, the radius R of the photosensitive drum 1 is generally in the range of 15 to 100 mm, and the amount of deflection U of the cleaning blade 71 is generally in the range of 0.5 to 2 mm. The radius R of the drum 1 is 25 mm
In this case, the cleaning blade holding member 72 is more likely to hit the photosensitive drum 1. In this case, it is effective to set the free end length L of the cleaning blade 71 to 6 mm or more.

Next, the pressure contact angle θ _{m of} the cleaning blade 71 to the photosensitive drum 1 is, for example, 15 °, 10 °, 5 °.
Up to 0 °, or so-called 0 ° when you start
A specific example for preventing the cleaning blade holding member 72 from contacting the photosensitive drum 1 will be described. For example, when the radius R of the photosensitive drum 1 is set to 100 mm, the free end length L of the cleaning blade 71 is set to 10 mm, and the amount of deflection U of the cleaning blade 71 is set to 2 mm, the image forming apparatus satisfies the condition of the above equation (1). In order to satisfy the condition, the thickness T of the cleaning blade holding member 72 is set as shown in the following table.

Pressure contact angle θ _m 15 ° 10 ° 5 ° 0 ° Thickness T 2.93mm or less 2.79mm or less 2.69mm or less 2.61mm or less That is, the pressure contact angle θ is 15 °, 10 °, 5 ° or so-called belly start Even in the state of 0 °, the thickness T of the cleaning blade holding member 72 is set to 2.93 mm or less, 2.79 mm or less, 2.69 mm or less, or 2.6.
By setting each to 1 mm or less, there is no possibility that the cleaning blade holding member 72 comes into contact with the photosensitive drum 1.

Although the illustrated example is for the thickness T of the cleaning blade holding member 72, other parameters can be set in the same manner. In this image forming apparatus, the charging device 2 is of a type that discharges by applying a high voltage to a charge wire, but is not limited thereto, and is not limited thereto. A charging device such as a sheet or a needle electrode may be used. The charging polarity applied here may be positive or negative depending on the charging polarity of the photosensitive drum 1, the developer D, or the like.

As the transfer device 5, here, a discharge type device using a charge wire is used as in the case of the charging device 2. However, the transfer device 5 is not limited to this. Is also good. The transfer method here employs a method in which the toner image on the photosensitive drum 1 is directly transferred to the recording paper SH. However, after the primary transfer to an intermediate transfer member such as an intermediate transfer drum or an intermediate transfer belt, further recording is performed. 2 on paper
The next transfer, that is, a so-called intermediate transfer method can be employed. In this case, any of the transfer devices described above may be used.

The separating device 6 is of a type in which an AC voltage is mainly applied to the charge wire to remove charges added to the recording paper SH and electrically separate the recording paper SH. Is not limited, and a mechanically separating type such as a separation claw or a separation belt can be used.
This is not particularly necessary when the recording paper can be forcibly separated by its stiffness, such as when the diameter of the photosensitive drum is small.

As the material of the cleaning blade 71 provided in the cleaning device 7, urethane rubber is used here. However, the material is not limited thereto, and silicon rubber, fluorine rubber, or the like may be used. Although the cleaning means using a single cleaning blade is employed here, one or more cleaning members such as a cleaning brush and a cleaning roller may be combined if a cleaning blade is provided. Also in this case, any of the above-mentioned examples can be used for the material of the cleaning blade.

The photosensitive drum 1 used here was an organic photosensitive member, but is not limited thereto.
An inorganic photoconductor such as a selenium telluride, a selenium photoreceptor, a Cds photoreceptor, or an amorphous silicon photoreceptor can also be used. In addition, the shape of the photoreceptor used here is a drum shape, but is not limited thereto, and a belt shape such as a photoreceptor belt can be used.

Next, another embodiment of the present invention will be described. FIG. 7 is a schematic configuration diagram of an image forming apparatus using a photosensitive belt instead of the photosensitive drum in the image forming apparatus shown in FIG. FIG. 7A shows an image forming apparatus in which the cleaning blade 71 of the cleaning device 7 is pressed against the surface of one curved surface of the photoreceptor belt.
(B) is a cleaning blade 7 of the cleaning device 7.
Reference numeral 1 denotes an image forming apparatus in which a flat portion of the surface of the photoreceptor belt is brought into pressure contact.

The image forming apparatus shown in FIG. 7A employs the same apparatus as the image forming apparatus shown in FIG. 5 except for the photosensitive member. However, since the recording paper SH can be forcibly separated, the separation device 6 is omitted. In this image forming apparatus, a photosensitive belt 1a is employed instead of the photosensitive drum shown in FIG.
Accordingly, the tension roller 21 and the belt roller 2
2, 23 are provided. The tension roller 21 and the belt rollers 22 and 23 are driven to rotate in the direction aa in the figure. The photoreceptor belt 1a is stretched over rollers 22, 23 and a tension roller 21 therebetween. The photoreceptor belt 1a is stretched by a tension roller 21, and its surface moves in the direction aa in the figure.

The belt roller 22 is opposed to the transfer device 5, and forms a transfer portion ST between the belt roller 22 and the transfer device 5 via the photosensitive belt 1a. The belt roller 23 is provided above the belt roller 22, and the print head 3 and the developing device 4 are provided between the rollers 22 and 23. In the cleaning device 7, the free end corner S of the cleaning blade 71 is pressed against the surface (curved surface) of the portion of the photosensitive belt 1a wound around the tension roller 21.

The charging device 2 and the charge removing device 8 are provided between the belt roller 23 and the tension roller 21. This image forming apparatus is also set so as to satisfy the condition of the above equation (1), similarly to the image forming apparatus shown in FIG. In this case, the radius of curvature R of the surface portion of the photoreceptor belt 1 a against which the free edge corner S of the cleaning blade of the above formula (1) is pressed is set to the radius of the tension roller 21. However, when the belt 1a is thick and its thickness cannot be ignored, the thickness may be added to make the radius of curvature.

The image forming apparatus shown in FIG.
9A is a modification of the image forming apparatus shown in FIG. Although the photoreceptor belt 1a is also used in this apparatus, the tension roller 21 and the belt rollers 22, 23 are driven to rotate in the direction a 'in FIG. Accordingly, the surface of the photoreceptor belt 1a moves in the direction of aa 'in the figure. Belt rollers 22, 2
3, a neutralizing device 8 and a cleaning device 7 'are provided. A tension roller 21 is provided on the left side of the cleaning device 7', and a developing device 4 'is provided on the left side thereof.

Developing device 4 'and cleaning device 7'
Is configured symmetrically with respect to the developing device 4 and the cleaning device 7 shown in FIG. 7A, and includes a developing roller 41, a supply roller 42, and a stirring roller 4 in the developing device 4 '.
3 and the toner conveying screw 74 in the cleaning device 7 'are rotated in the directions of b', c ', d' and e ', respectively. The charging device 2 and the print head 3 are provided between the belt roller 23 and the tension roller 21. The surface portion of the photoreceptor belt 1a against which the free edge corner S of the cleaning blade 71 is pressed is flat.

In this image forming apparatus, the thickness T of the edge of the cleaning blade holding member 72 near the corner of the free edge of the cleaning blade facing the photoreceptor belt 1a,
Cleaning blade 71 from cleaning blade holding member 72 to cleaning blade free end edge corner S
The relationship between the free end length L of the cleaning blade, the amount U of bending of the free edge portion S of the cleaning blade against the photoreceptor belt 1a and the predetermined allowable minimum press contact angle θ _m of the cleaning blade 71 on the photoreceptor belt 1a is as follows. _{U - (2LTcosθ m -3UTsinθ m)} / √ (4L 2 + 9U 2)> 0 ... it is set so as to satisfy the condition of equation (2).

Until the allowable pressure contact angle θ _{m of the} cleaning blade 71 to the photoreceptor belt 1a is 15 °, 10 °, 5 ° or the state where the so-called antinode starts to be 0 °, the cleaning blade holding member 72 keeps the photoreceptor belt 1a. The following is a specific example that does not make contact with. For example, when the free end length L of the cleaning blade 71 is set to 10 mm and the amount of deflection U of the cleaning blade 71 is set to 2 mm, the thickness T of the cleaning blade holding member 72 is as shown in the following table.

Pressure contact angle θ _m 15 ° 10 ° 5 ° 0 ° Thickness T 2.35 mm or less 2.23 mm or less 2.15 mm or less 2.08 mm or less That is, the pressure contact angle θ _m is 15 °, 10 °, 5 ° or so-called belly hit Even at the start of 0 °, the thickness T of the cleaning blade holding member 72 is 2.35 mm or less, 2.23 mm or less, 2.15 mm or less, or 2.08 mm or less.
By setting it to be equal to or less than mm, there is no possibility that the cleaning blade holding member 72 comes into contact with the photoreceptor belt 1a.

Although the example shown here is for the thickness T of the cleaning blade holding member 72, other parameters can be set similarly. FIG. 8 shows FIG.
FIG. 8 is a view showing another embodiment of the cleaning blade holding member 72 provided in the cleaning device 7 shown in FIG. 7, and an end of the cleaning blade holding member 72 near the corner of the free edge of the cleaning blade facing the photosensitive drum 1. Q
1 shows a thickness T that is smaller than a portion adjacent to the end Q1.

The cleaning device 7a shown in FIG.
FIG. 8 shows an example in which the end portion Q1 of the cleaning blade holding member 72a is inclined to reduce its thickness T.
The cleaning device 7b shown in (B) has at least two steps at the end Q1 of the cleaning blade holding member 72b, and has a thickness T as it goes to the edge of the edge.
Is made thinner.

Thus, even if the pressure contact angle θ of the cleaning blade 71 to the photosensitive drum 1 is reduced, the risk of the cleaning blade holding member 72 contacting the photosensitive drum 1 can be reduced. FIG. 9 is a diagram illustrating a cleaning device that employs a blade sandwiching type holding member 72c instead of the cleaning blade holding member 72 provided in the cleaning device illustrated in FIG.

The cleaning blade 71 includes the holding member 7.
It is sandwiched and supported by 2c. Thereby, the cleaning blade 71 can be reliably held. Although the blade sandwiching member 72c is formed integrally here, it may be constituted by a plurality of members. Here, the holding member thickness T is the thickness T of the portion 7210 facing the photosensitive drum 1 here.

[0068]

According to the present invention, an electrostatic latent image formed on an electrostatic latent image carrier having a moving surface is developed using a developer containing colored particles, and the obtained visible image is developed. An image forming apparatus comprising: a cleaning blade that is transferred onto a transfer target body and that is not transferred and remains on the electrostatic latent image carrier with a cleaning blade pressed against the electrostatic latent image carrier; Even if there is a slight thickness error in the blade, there is no problem in removing the residual particles, and even if the cleaning blade is used for a long time while being pressed against the electrostatic latent image carrier, Even when the cleaning blade is left in the environment for a long time, the cleaning blade holding member is provided with the cleaning blade holding member regardless of the radius of curvature of the surface portion of the electrostatic latent image carrier against which the cleaning blade is pressed. Or there is no possibility of contact, or it is possible to provide an extremely small image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a contact relationship between a cleaning device and an electrostatic latent image carrier in an image forming apparatus.

FIG. 2 is an enlarged view of a contact portion between a cleaning blade and an electrostatic latent image carrier shown in FIG. 1 and a peripheral portion thereof.

FIG. 3 is a diagram showing that a cleaning blade can be regarded as a cantilever.

FIG. 4 is a view showing a state in which the cleaning blade shown in FIG. 2 is bent in an arc.

FIG. 5 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

6 is an enlarged view of the cleaning device shown in FIG.

FIG. 7A is a schematic configuration diagram of an image forming apparatus in which a surface portion of a photosensitive belt to which a free edge of a cleaning blade is pressed is a curved surface; FIG. 7B is a schematic configuration diagram of the image forming apparatus; FIG. 2 is a schematic configuration diagram of an image forming apparatus in which a surface portion of a photoreceptor belt to which an edge corner is pressed is flat.

FIG. 8A is a diagram showing a state in which the end of the cleaning blade holding member is inclined to reduce its thickness, and FIG. 8B is a diagram showing at least two steps at the end of the cleaning blade holding member. FIG. 7 is a view showing a structure in which the above-described steps are provided, and the thickness thereof is reduced as approaching an edge thereof.

9 is a diagram illustrating a cleaning device that employs a blade sandwiching type holding member instead of the cleaning blade holding member provided in the cleaning device illustrated in FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum 1a Photoconductor belt 2 Charging device 3 Split head 4, 4 'Developing device 5 Transfer device 6 Separating device 7, 7', 7a, 7b, 7c Cleaning device 8 Static eliminator 9 Timing roller pair 10, 11 Transport guide DESCRIPTION OF SYMBOLS 12 Fixing device 21 Tension roller 22, 23 Belt roller 41 Developing roller 42 Supply roller 43 Stirring roller 71 Cleaning blade 72, 72a, 72b, 72c Cleaning blade holding member 73 Press-contact spring 74 Toner transport screw 700 Cleaning device case 720 Bending part is cleaned. Shaft 721 fixed to the apparatus case 721 A portion having a thickness ahead of the bent portion of the cleaning blade holding member 722 A portion behind the bent portion ST Transfer portion L Laser beam D Developer SH Recording paper C Photoconductor of cleaning blade Surface facing the drum S Free edge corner of the cleaning blade S1 Edge opposite to the free edge corner of the cleaning blade T Thickness of the edge of the cleaning blade holding member near the blade free edge corner A The center (fulcrum) of the axis where the bent portion is fixed to the cleaning device case R The radius of curvature of the surface of the photosensitive drum L The free end length of the cleaning blade U The bending of the free end edge of the cleaning blade against the photosensitive drum by pressing. Quantity a, b Tangent θ Pressing angle of cleaning blade to photosensitive drum PW1, PW2, PW3, PW4 Power supply

Claims (5)

[Claims] 1. An electrostatic latent image formed on an electrostatic latent image carrier having a moving surface is developed using a developer containing colored particles, and the obtained visible image is transferred to a transfer target. An image forming apparatus for removing residual particles remaining on the electrostatic latent image carrier without being transferred by a cleaning device, wherein the cleaning device includes a cleaning blade, and a cleaning blade holding the cleaning blade in a cantilever manner. A cleaning blade holding member, wherein the cleaning blade is pressed against the surface of the electrostatic latent image carrier at a free edge corner portion following a surface facing the electrostatic latent image carrier; A cantilevered end of the cleaning blade opposite to the free edge corner in a state where at least a part thereof is disposed between the cleaning blade and the electrostatic latent image carrier. It has lifting and, pivotally mounted on a fulcrum around the place,
A spring force is applied in a direction in which the cleaning blade free edge corner is pressed against the electrostatic latent image carrier surface, and the cleaning blade free edge corner is pressed against the electrostatic latent image carrier surface. A radius of curvature of the portion, a thickness of the cleaning blade holding member facing the electrostatic latent image carrier, near an edge of the cleaning blade free edge, and a cleaning blade free edge from the cleaning blade holding member. The correlation between the free end length of the cleaning blade up to a corner, the pressure contact angle of the cleaning blade to the electrostatic latent image carrier, and the amount of deflection of the cleaning blade free edge at the pressure contact angle is as described above. Until the pressure contact angle reaches 0 ° from a value larger than 0 °, the cleaning blade holding member is prevented from contacting the electrostatic latent image carrier. An image forming apparatus characterized in that it is a constant. 2. The cleaning blade holding member according to claim 1, wherein a thickness of an end of the cleaning blade holding member, which faces the electrostatic latent image carrier, is closer to a corner of the free edge of the cleaning blade than a portion adjacent to the end. The image forming apparatus according to claim 1. 3. An electrostatic latent image formed on an electrostatic latent image carrier having a moving surface is developed using a developer containing colored particles, and the obtained visible image is transferred to a transfer target. An image forming apparatus for removing residual particles remaining on the electrostatic latent image carrier without being transferred by a cleaning device, wherein the cleaning device includes a cleaning blade, and a cleaning blade holding the cleaning blade in a cantilever manner. A cleaning blade holding member, wherein the cleaning blade is pressed against the surface of the electrostatic latent image carrier at a free edge corner portion following a surface facing the electrostatic latent image carrier; A cantilevered end of the cleaning blade opposite to the free edge corner in a state where at least a part thereof is disposed between the cleaning blade and the electrostatic latent image carrier. It has lifting and, pivotally mounted on a fulcrum around the place,
A spring force is applied in a direction in which the cleaning blade free edge corner is pressed against the electrostatic latent image carrier surface, and the cleaning blade free edge corner is pressed against the electrostatic latent image carrier surface. The radius of curvature R of the portion, the thickness T of the cleaning blade holding member facing the electrostatic latent image carrier near the free edge of the cleaning blade, and the cleaning blade free from the cleaning blade holding member. the free end length of the cleaning blade to the edge corner L, the cleaning blade free edge at a predetermined permissible minimum pressure angle theta _m and piezoelectric contact angle theta _m to the latent electrostatic image bearing member of said cleaning blade The relationship between the amount of deflection U of the corner portion is as follows: when the surface portion of the electrostatic latent image carrier on which the free edge portion of the cleaning blade is pressed is a curved surface, R + U− ( 2LTcosθ _m -3UTsinθ _m ) / √ (4L ² + 9U ² )>
In order to satisfy the condition of √ (R ² −L ² ), when the surface portion of the electrostatic latent image carrier on which the free edge corner of the cleaning blade is pressed is flat, U− (2LTcosθ _m −3UT sin θ _m ) / √ (4L ² + 9U ² )> 0. An image forming apparatus characterized by being set so as to satisfy the following condition. 4. An image forming apparatus according to claim 3, wherein said pressure contact angle θ _m is not more than 15 ° and not less than 5 °. 5. The cleaning blade holding member according to claim 1, wherein a thickness of an end portion of the cleaning blade holding member which faces the electrostatic latent image carrier near a corner of a free edge of the cleaning blade is thinner than a portion adjacent to the end portion. The image forming apparatus according to claim 3, wherein: