JP4228365B2 - Excess solvent removal device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used in a wet electrophotographic printing machine in which a toner image is developed on the surface of a latent image holding member with liquid toner, and a developing device is used to remove excess solvent on the surface of the latent image holding member. It is related with the excess solvent removal apparatus provided in the downstream of this.
[0002]
[Prior art]
The wet electrophotographic printing machine is configured as shown in, for example, Patent Document 1, and around the latent image holding member (photosensitive drum), from the rolling contact portion between the latent image holding member and the intermediate transfer member to the downstream side in the rotation direction. A plurality of image forming means consisting of a charger, an exposure device, and a developing device, and removal of excess solvent for removing the solvent remaining on the surface of the latent image holding member that has passed through the image forming means on the most downstream side thereof Means are arranged.
[0003]
The conventional surplus solvent removing means is as shown in FIG. 7, and a shielding cylinder a made of a non-breathable material is used as a core, and an elastic porous layer b is fixed to the outside of the shielding cylinder a. The squeezing roller d made of the outer cylinder c having the porous structure is brought into contact with the latent image holding member e. The shielding cylinder a has a notch-shaped vent f facing the inner surface of the outer cylinder c of the squeezing roller d at a position shifted in the rotational direction from the position of the squeezing roller d facing the latent image holding member d. And a decompression device such as a vacuum pump is connected to the vent hole f.
[0004]
Then, the solvent absorbed from the surface of the latent image holding body e by the elastic porous layer b of the squeezing roller d rotating in synchronization with the latent image holding body e deviates from the portion facing the latent image holding body e. The excess solvent g in the latent image holder e is sucked at the position and is collected without being affected by the suction force from the vent f.
[0005]
[Patent Document 1]
JP 2002-23504 (paragraphs 0044 to 0048, FIG. 3)
[0006]
[Problems to be solved by the invention]
In the conventional surplus solvent removing device, the portion of the squeezing roller d facing the latent image holding member e is shielded, so that the solvent is removed from the surface of the latent image holding member on the outer peripheral portion of the squeezing roller d. Since the process is performed only with the absorbing power of the elastic porous layer d, the solvent cannot be recovered if the absorbing power of the elastic porous layer d decreases due to clogging or deterioration.
[0007]
Further, in order to increase the suction force inside the squeezing roller d, the shielding section by the shielding cylinder a is long, and thus the opening width of the vent hole f is reduced. There was a problem that the suction of the solvent at the vent f was not in time.
[0008]
The present invention has been made in view of the above, and even if the elastic porous layer provided on the outer periphery of the squeeze roller is clogged or the like, it is possible to prevent the recovery ability of the excess solvent from the latent image holding member from being lowered. It is another object of the present invention to provide a surplus solvent removing apparatus capable of reliably collecting surplus medium even under high speed rotation.
[0009]
In order to achieve the above object, an excess medium removing device according to the present invention is a developing device of a wet electrophotographic printing machine in which a toner image is developed on the surface of a latent image holding body by a developing device using liquid toner. In the surplus solvent removing device provided on the downstream side so as to face the surface of the latent image holding member, an inner cylinder in which a part of the peripheral wall in the circumferential direction is formed in a blind shape and the other part is formed in a porous configuration, and the entire peripheral wall of the peripheral wall A squeezing roller comprising an outer cylinder that is provided with a porous structure and is provided with an elastic porous layer on the outer peripheral side and is rotatably fitted to the inner cylinder. Is fixed to the support base so that the angle is adjustable in the rotation direction so that the head is directed to the latent image holding member side, and the rotation driving means is connected to the outer cylinder. The support base is configured to be movable in a direction in which the elastic porous layer of the squeezing roller is in contact with and away from the latent image holding member, and a doctor blade is in contact with the elastic porous layer of the squeezing roller. In addition, a solvent receiver was provided below the squeeze roller.
[0010]
[Operation]
According to this configuration, the squeezing roller moves to the squeezing position where the elastic porous layer is in contact with the latent image holding member and rotates the outer cylinder provided with the elastic porous layer. The solvent on the surface is squeezed by the elastic porous layer, and sucked into the inner cylinder through the outer cylinder having a porous structure and the peripheral wall of the inner cylinder by the negative pressure in the inner cylinder.
[0011]
At this time, since the blind member is provided in the portion of the inner cylinder facing the latent image holding body, the elastic porous layer of the portion facing the latent image holding body and in contact with the latent image holding body is exposed from the inner cylinder. Negative pressure is not affected. Accordingly, the solvent on the surface of the latent image carrier is absorbed only by the contact or pressing action of the elastic porous layer, and the toner image on the surface of the latent image carrier is not transferred to the elastic porous layer side.
[0012]
In the above action, when the elastic porous layer is clogged or deteriorates and the absorption capacity of the solvent by the elastic porous layer decreases, it becomes impossible to recover the solvent from the surface of the latent image holding member. The cylinder is angularly displaced in the rotational direction of the outer cylinder, and the position of the blind portion is shifted in the circumferential direction so that the porous portion of the inner cylinder is brought close to the facing portion between the elastic porous layer and the latent image holder. Thus, the solvent on the surface of the latent image holding member is supplementarily sucked by the negative pressure action of the inner cylinder, and the solvent recovery force is recovered.
[0013]
Further, in the above operation, the solvent absorbed in the elastic porous layer is sucked to the inner cylinder side in the whole area of the part off the blind part of the cylinder. Since the area of the porous component of the inner cylinder is larger than that of the blind part, the suction range in the inner cylinder becomes longer in the circumferential direction, and the recovery of the solvent by the squeeze roller is ensured even under high-speed rotation. It can be carried out.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a main part of a wet electrophotographic printing machine equipped with a surplus solvent removing apparatus 1 according to the present invention, and a photosensitive drum 2 which is an example of a latent image holding member, and an intermediate transfer roller 3. The photosensitive drum cleaner 4, the static eliminator 5, a plurality of sets, for example, the first and second image forming apparatuses 6 a and 6 b, and the drying apparatus 7, are provided downstream from the rolling contact portion with respect to the rotation direction. The surplus medium removing device 1 is disposed between the image forming device 6 b on the most downstream side and the drying device 7.
[0015]
The wet electrophotographic printing machine is arranged symmetrically about one place on the peripheral surface of the intermediate transfer roller 3, and the continuous paper W passes between the intermediate transfer rollers 3, whereby double-sided printing is performed on this. ing. It is also possible to perform single-sided printing by rolling the impression cylinder onto the intermediate transfer roller 3.
[0016]
Each set of the image forming apparatuses 6a and 6b has substantially the same configuration, and the charger device 8, the exposure device (latent image forming device) 9, the developing device 10, and the squeeze roller 11 are arranged from the upstream side in the rotation direction of the photosensitive drum 2. They are arranged in order.
[0017]
In this wet electrophotographic printing machine, the toner and the potential remaining on the surface of the photosensitive drum 2 are removed by the photosensitive drum cleaning device 4 and the static eliminator 5 as the photosensitive drum 2 rotates. Next, toner images for two colors are formed by the first and second image forming apparatuses 6a6b.
[0018]
In each of the image forming apparatuses 6a and 6b at this time, the surface of the photosensitive drum 2 is charged to a predetermined voltage by the charger device 8, and a laser beam image-modulated by the exposure device 9 is irradiated on the surface to statically. An electrostatic latent image is formed, and the electrostatic latent image is developed into a toner image by the developing device 10. The developing toner at this time is supplied to the surface of the photosensitive drum 2 together with the solvent. The excess solvent at this time is removed by the squeeze roller 11.
In such a wet electrophotographic printing machine, excess media cannot be removed by the squeeze roller 11 in each of the image forming apparatuses 6a and 6b, and the drying device 7 is still on the surface of the photosensitive drum 2 that has passed through both the image forming apparatuses 6a and 6b. Then there are surplus media that cannot be removed. The surplus solvent removing device 1 in the present invention is for removing surplus solvent existing on the downstream side of both the image forming apparatuses 6a and 6b.
[0020]
Below, the structure of this excess solvent removal apparatus 1 is demonstrated based on FIG. 2, FIG.
[0021]
In the figure, reference numeral 15 denotes a squeeze roller that contacts the photosensitive drum 2 and rotates in the opposite direction (same circumferential direction). The squeezing roller 15 is closely fitted to an inner cylinder 17 having both end shafts supported by brackets 16a and 16b, and the outer cylinder 17 so as to be freely rotatable, and an elastic porous layer such as a sponge layer 18 is provided on the outer periphery. The outer cylinder 19 is laminated. The outer cylinder 19 has a porous structure having a large number of small holes 20 on the entire circumference of the peripheral wall thereof. Further, on the peripheral wall of the inner cylinder 17, a contact portion of the squeeze roller 16 with the photosensitive drum 2, that is, a portion facing the photosensitive drum 2 is a blind portion 17 a over a predetermined angle θ in the circumferential direction. The other peripheral walls have a porous structure in which a large number of small holes 21 are provided over the entire length. The blind portion 17a has an angle θ of about 90 degrees and is provided over the entire length.
[0022]
Shafts 22a and 22b protruding from both ends of the inner cylinder 17 are fixed to the brackets 16a and 16b so as to be angularly displaceable in the rotational direction. A passage 24 communicating with the inner hollow portion of the inner cylinder 17 is provided at the shaft center of one shaft 22a. The passage 24 is connected to a suction device (not shown) via a pipe 25 connected to the end of the shaft 22a. It is communicated.
[0023]
Both ends of the outer cylinder 19 are rotatably supported by the shafts 22 a and 22 b of the inner cylinder 17, and a pulley 26 a is fixed to one end, and the pulley fixed to the pulley 26 a and the output shaft of the drive motor 27. A belt 29 is wound around 26b, and the outer cylinder 19 is rotated by the drive motor 27 so that the outer cylinder 19 runs in the opposite direction to the photosensitive drum 2, that is, the contact peripheral surface runs in the same direction.
[0024]
Brackets 16 a and 16 b for fixing and supporting the cylinder 17 are supported by a support base 28. Brackets 30a and 30b provided at both ends of the support base 28 are supported by guide rods 32a and 32b provided on the front and rear frames 31a and 31b so as to be movable in a direction away from the photosensitive drum 2. . The drive motor 27 is coupled to the support base 28 via a support arm 33 so as to be movable in the tension adjusting direction of the belt 29.
[0025]
The support base 28 is provided with a solvent receiver 34 formed in a dish shape so as to receive the solvent dripped from the sponge layer 18 of the squeezing roller 15. The surface of the sponge layer 18 of the squeezing roller 15 is provided on the solvent receiver 34. A doctor blade 35 is provided so as to be movable in the contact direction.
[0026]
The brackets 30a and 30b at both ends of the support base 28 are provided with grooves 36 and 36 in a direction perpendicular to the moving direction thereof. Cylinder devices 37 and 37 that operate in the moving direction of the support base 28 are fixed to the frames 31a and 31b on both sides of the support base 28. The cylinder rods 37 and 37b rotate in the direction perpendicular to the axis of the piston rod. Locking pieces 38a, 38b that move are provided. The locking pieces 38a and 38b are adapted to engage with the grooves 36 and 36 when the support pieces 28a and 38b are rotated toward the brackets 30a and 30b.
[0027]
The positional relationship between the cylinder devices 37, 37 and the locking pieces 38 a, 38 b provided on the piston rods and the grooves 36, 36 engaged with the cylinder members 37, 37 is that the sponge layer 18 of the squeeze roller 15 has a predetermined pressure (deformation amount). ), The locking pieces 38a and 38b are engaged with the grooves 36 and 36 in the standby position where this portion is separated by a predetermined distance (for example, 7 mm) from the aperture position that contacts the photosensitive drum 2. Thus, the cylinder devices 37, 37 extend and contract over this range. Reference numerals 39 and 39 denote stoppers 10 for setting the moving end of the diaphragm roller 15 toward the photosensitive drum 2, and the setting position is variable.
[0028]
The squeezing roller 15 can be moved to a maintenance position that is far away from the contact / separation stroke with respect to the photosensitive drum 2, and the cylinder device 37 is positioned at a position corresponding to the groove 36 of one bracket 30 b at the end portion. Another locking piece 38c having the same function as the locking piece 38b provided on the piston rod is detachably provided in the groove 36.
[0029]
The operation of the surplus solvent removing apparatus 1 having the above configuration will be described below.
The squeezing roller 15 of the surplus solvent removing apparatus 1 is manually moved along the guide rods 32a and 32b over a position where the sponge layer 18 is close to the surface of the photosensitive drum 2 and a maintenance position which is greatly separated from the position. Moved.
[0030]
Then, the squeezing roller 15 is moved to a position close to the photosensitive drum 2, and the engaging pieces 37a and 37b are rotated and engaged with the grooves 36 of the brackets 30a and 30b provided at both ends of the support base 28 at this time. Match. In this state, the squeezing roller 15 is rotated by the drive motor 27, and the cylinder devices 37 and 37 are extended to move the squeezing roller 15 to the squeezing position, whereby the sponge layer 18 of the squeezing roller 15 is moved to the photosensitive drum 2. The solvent which is pressed against the surface and adheres to the surface of the photosensitive drum 2 is squeezed by the sponge layer 18. At this time, the air in the inner cylinder 17 is sucked by the suction device through the pipe 25, and the inside is at a negative pressure. Therefore, the negative pressure is supplied to the outer cylinder through the small holes 20 and 21. The solvent which acts on the outer surface of 19 and is squeezed into the sponge layer 18 is removed from the outer peripheral surface of the outer cylinder 19 in the entire position away from the blind portion 17a of the inner cylinder 17, that is, in an area sufficiently larger than the blind portion. It is sucked into the inner cylinder 17 through the small holes 20 and 21 provided in the peripheral walls of the outer cylinder 19 and the inner cylinder 17, and then sucked out to the suction device through the pipe 25.
[0031]
Also, at this time, a portion of the outer cylinder 19 facing the photosensitive drum 2 is provided on the peripheral wall of the inner cylinder 17 by providing the blind portion 17a not provided with the small hole 21 at a position facing the photosensitive drum 2. The negative pressure by the suction device is not applied to the inner surface. Therefore, the suction force is not applied to the portion of the sponge layer 18 that is in contact with the photosensitive drum 2.
[0032]
Therefore, in the portion of the sponge layer 18 that is in contact with the photosensitive drum 2, the forced suction force due to the negative pressure does not act, and the surplus solvent on the surface of the photosensitive drum 2 is absorbed by the liquid absorption force by the sponge itself. Is done. As described above, the solvent is sucked into the inner cylinder 17 through the small holes 20 and 21 at a position past the blind portion 17a of the inner cylinder 17.
[0033]
For this reason, suction force due to negative pressure does not act on the surface of the photosensitive drum 2 where the sponge layer 18 of the squeezing roller 15 is in contact, and an excess solvent is simply pressed against the sponge layer 18 to remove excess solvent. The toner forming the toner image on the surface of the photosensitive drum 2 is prevented from adsorbing to the sponge layer 18 due to the negative pressure in the squeeze roller 15, and the surface of the sponge layer 18 is prevented from adsorbing to the surface of the sponge layer 18. Toner transfer can be prevented.
[0034]
Further, when the portion of the sponge layer 18 that is in contact with the photosensitive drum 2 is located at a portion deviated from the position of the blind portion 17a of the inner cylinder 17, the solvent is sucked by the negative pressure of the inner cylinder 17. Thus, since the amount of impregnation of the solvent is always small in the portion facing the photosensitive drum, the solvent in this portion is satisfactorily performed.
[0035]
In such an excess solvent removing action, when the sponge layer 18 is clogged or deteriorated by the toner and the liquid absorption power is reduced, the ability of the squeeze roller 15 to remove the solvent is lowered. .
[0036]
In such a case, as shown in FIG. 3B, the inner cylinder 17 is angularly displaced, and the position of the blind portion 17a is shifted by the displacement angle R in the circumferential direction, so that the porous structure of the cylinder 17 is obtained. The portion is brought close to the facing portion between the sponge layer 18 of the outer cylinder 19 and the photosensitive drum 2.
[0037]
As a result, a negative pressure from the inner cylinder 17 acts on the inside of a part of the sponge layer 18 that is in contact with the photosensitive drum 2, and the liquid absorption force of the sponge layer 18 in this part is the above negative pressure. A liquid absorption force due to pressure is applied to correct a decrease in liquid absorption force of the sponge layer 18 itself.
[0038]
The solvent that is absorbed in the sponge layer 18 and remains in the sponge layer 18 is scraped by the doctor 35 as the squeezing roller 15 rotates and is received by the solvent receiver 34.
[0039]
The diaphragm roller 15 is moved to a standby position separated from the photosensitive drum 2 as shown in FIG.
[0040]
Further, by removing the locking pieces 38a and 38b provided on the piston rods of the cylinder devices 37 and 37 from the grooves 36 and 36 of the brackets 30a and 30b, the squeezing roller 15 is removed from the photosensitive drum 2 as shown in FIG. It is moved to a maintenance position that is largely separated. At this time, the other locking piece 38a is locked to the brackets 30a and 30b.
[0041]
In the above embodiment, an example in which the sponge layer 18 is laminated on the outer peripheral surface of the outer cylinder 19 has been described. However, this is not limited to this, and the point is that the surface of the latent image holding member is elastically contacted. Any material can be used as long as it can absorb the remaining solvent.
[0042]
【The invention's effect】
According to the present invention, the excess solvent on the surface of the latent image holding member can be removed without exerting a forcible force due to negative pressure, and thus without adversely affecting the toner image on the surface of the latent image holding member.
[0043]
Then, when the liquid absorption force of the elastic porous layer itself of the squeeze roller is reduced due to clogging or deterioration thereof, the inner cylinder of the squeeze roller is angularly displaced, so that the latent image holder of the elastic porous layer is obtained. A negative pressure is applied to the inside of a part of the opposed portion to the liquid, so that the liquid absorption force due to this negative pressure can be applied at the time of assistance, and at this time, a reduction in excess solvent recovery force by the squeeze roller is prevented. be able to.
[0044]
In addition, according to the present invention, the suction range in the inner cylinder is larger because the area of the porous component provided on the peripheral wall is larger than the circular part provided on the peripheral wall of the inner cylinder. It becomes longer in the circumferential direction, and the solvent can be reliably recovered by the squeeze roller even under high speed rotation.
[0045]
Further, when the doctor blade is brought into contact with the liquid absorbing material layer, the solvent remaining in the liquid absorbing material layer and the toner transferred to the surface of the liquid absorbing material layer are scraped off.
[Brief description of the drawings]
FIG. 1 is a schematic configuration explanatory view showing a main part of a wet electrophotographic printing machine equipped with a surplus solvent removing apparatus according to the present invention.
FIG. 2 is a partially broken plan view showing a main part of the present invention.
3A is an enlarged cross-sectional view taken along the line AA in FIG. 2, and FIG.
FIG. 4 is an operation explanatory diagram showing a standby state.
FIG. 5 is an operation explanatory diagram showing a maintenance state.
6 is an enlarged cross-sectional view taken along the line B-B in FIG. 4;
FIG. 7 is a cross-sectional view showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Excess solvent removal apparatus, 2 ... Photosensitive drum (latent image holding body), 3 ... Intermediate transfer roller, 4 ... Photosensitive drum cleaner, 5 ... Static elimination apparatus, 6a, 6b ... Image forming apparatus, 7 ... Drying apparatus, DESCRIPTION OF SYMBOLS 8 ... Charger apparatus, 9 ... Exposure apparatus, 10 ... Developing apparatus, 11 ... Squeeze roller, 15 ... Diaphragm roller, 16a16b ... Bracket, 17 ... Inner cylinder, 17a ... Blind part, 18 ... Sponge layer (elastic porous layer) , 19 ... outer cylinder, 20, 21 ... small hole, 22a, 22b ... shaft, 24 ... passage, 25 ... piping, 26a, 26b ... pulley, 28 ... support base, 27 ... drive motor, 29 ... belt, 30a, 30b ... Bracket, 31a, 31b ... Frame, 32a, 32b ... Guide rod, 33 ... Support arm, 34 ... Solvent receiver, 35 ... Doctor blade, 36 ... Groove, 37 ... Cylinder device, 38a, 38b 38c ... engaging piece.

Claims (3)

A surplus solvent removing device provided on the downstream side of a developing device of a wet electrophotographic printing machine that develops a toner image on the surface of the latent image holding member with a developing device using liquid toner, facing the surface of the latent image holding member. In
An inner cylinder in which a part of the peripheral wall in the circumferential direction is formed in a blind shape and the other part is in a porous configuration, and the entire peripheral wall of the peripheral wall is configured in a porous configuration, and an elastic porous layer is provided on the outer peripheral side, and the above inner cylinder A squeezing roller consisting of an outer cylinder that is rotatably fitted to the inner cylinder, and supports the inner cylinder of the inner cylinder so that the blind portion of the inner cylinder faces the latent image holding body and the angle can be adjusted in the rotation direction. A surplus solvent removing apparatus, characterized in that it is fixed to a table and a rotation driving means is connected to an outer cylinder. 2. The surplus solvent removing apparatus according to claim 1, wherein the support base is movable in a direction in which the elastic porous layer of the squeezing roller comes in contact with and separates from the latent image holding member. 3. The surplus solvent removing apparatus according to claim 1, wherein a doctor blade that contacts the elastic porous layer of the squeezing roller is provided, and a solvent receiver is provided below the squeezing roller.

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