JP2002278300A - Toner supply system of electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an electrophotographic device which uses liquid toner of high viscosity and high density small-sized with a simple constitution even for liquid with inferior flowability and to supply toner uniformly over the entire print width. SOLUTION: A supply roller supplies a developing roller with liquid toner. Further, a toner supply pan is provided leaving a space with the supply roller surface so as to supply the liquid toner to the supply roller while sealing the space and the liquid toner is supplied to the space. A means which detects the pressure in the space is provided and detects a rise in the pressure in a container due to the supply of the toner to stop supply of the toner. Consequently, even toner whose viscosity varies greatly depending upon a shearing speed can securely be supplied to the entire area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner supply system for an electrophotographic apparatus using a non-volatile, high-viscosity, high-concentration liquid toner, and more particularly, to a uniform developing solution applied to a developing roller over the entire printing width. And a toner supply method.

[0002]

2. Description of the Related Art In an electrophotographic apparatus using a high-viscosity, high-concentration developer composed of a high-concentration toner dispersed in silicone oil or the like, the liquid toner is applied to a developing roller or a developing belt. Is used to develop the electrostatic latent image on the photoreceptor, but it is difficult to uniformly apply a high-viscosity, high-concentration liquid toner to the developing roller.

FIG. 10 shows an example of high viscosity and high density characteristics of a liquid toner usable in the present invention.
In the figure, the horizontal axis represents the shear rate [1 / S], the vertical axis represents the shear stress [Pa] in the upper figure, and the viscosity [mPaS] in the lower figure.

A high-viscosity, high-concentration liquid toner has solid particles dispersed in a liquid carrier and has complicated viscosity characteristics. The liquid toner shown as an example in FIG. 10 has a very high toner viscosity in a region where the shear rate is low.
In the low shear rate range, the viscosity was as high as 10,000 [mPaS], but decreases in the high shear rate range to 100 [mPaS]. This means that it will appear hard until a certain level of force is applied, but will suddenly flow past it. It can be said that the yield point is high and the flow is bad.

The difficulty in supplying a liquid toner having such characteristics will be described with reference to FIG. Considering the case where the toner is to be spread in a certain range (span), for example, A4 width or A3 width, when the liquid toner advances inside the tube, the inside of the tube is as shown in FIG. A speed profile has been formed. The velocity is 0 at the pipe wall surface and the maximum velocity at the center. What is the shear rate?
Since the velocity profile is a gradient in the lateral direction (y-direction), in the example shown, the shear rate near the wall surface is large,
In addition, the central portion is small, and a portion having a shear rate of 0 exists at the center. When a high-viscosity, high-concentration liquid toner is caused to flow through such a conduit, the central portion is integrated because the shearing speed is low, and a "plug flow" state occurs in which only the wall surface flows.

In order to uniformly supply the liquid toner in such a state over a certain span, it is conceivable to form holes in the pipe at equal intervals as shown in FIG.
As shown in (a), in the case of a Newtonian fluid, its pressure distribution becomes higher as it is closer to the pump, but becomes uniform. Therefore, by adjusting the size of the holes, it is possible to supply the pressure uniformly over a certain span. Is possible. However, in the case of a fluid having high non-Newtonian fluid characteristics (high viscosity and high shear rate dependence), such as a high-viscosity, high-concentration liquid toner, as shown in FIG. There is a problem that the amount of incoming toner becomes uneven. It is considered that this is because the pressure distribution in the pipe becomes uneven due to the flow of the toner.

A high-viscosity, high-concentration liquid toner has a very high viscosity dependence on the shear rate. When such a toner is injected into a dynamic conveyance path, as described above, the pressure distribution inside the conveyance path is affected by the movement of the toner, and as a result, a spatial difference occurs in the toner discharge amount, and It is also unstable. This is because the kinetic energy due to toner discharge exchanges energy with pressure, and as a result, the pressure at the outflow drops temporarily and then recovers, forming a kind of stick-slip vibration system. Conceivable.

[0008] From such a viewpoint, the present applicant has previously described FIG.
(Japanese Patent Laid-Open No. 2000-2000)
-250318). As illustrated, the developing roller 15 contacts the photoreceptor 10 to supply a liquid developer. Applicator rollers 16 and 17 and a guide frame 18 are provided in order to spread the developing solution on the surface of the developing roller 15 and apply it in a thin layer. The liquid toner is supplied from a toner container (not shown) to the toner supply port 11.
Is introduced into the space formed by the two applicator rollers 16, 17 and the guide frame 18, and the space is filled with the liquid toner. With such a configuration, the liquid toner is statically confined, and the toner can be spread and spread over the entire printing area while the pressure is uniformly applied to the entire toner.

However, the configuration shown is complicated and large, requiring at least two applicator rollers and a guide frame having a complicated shape.
This is an obstacle to miniaturization of the device.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is directed to a liquid having a poor flow, such as an electrophotographic apparatus using a non-volatile, high-viscosity, high-concentration liquid toner. Another object of the present invention is to make it possible to reduce the size of the apparatus with a simple configuration and to supply toner uniformly over the entire printing width.

Another object of the present invention is to provide a structure which guarantees a sufficient supply of toner to form a good image and prevents toner from leaking from a developing unit and stagnation of toner.

Further, the present invention provides a toner discharge port,
Even when the toner is excessively supplied, the toner is collected, circulated to a supply bottle, and reused, so that the overall toner consumption is suppressed.

[0013]

The basic idea of the present invention is to analyze in detail the characteristics of a toner having a complicated viscoelastic behavior such as a high-viscosity, high-concentration toner exhibiting non-volatility, It was obtained by experimental verification. To solve this problem, special containers have been designed to contain the toner statically, to spread the toner evenly with pressure evenly over the toner, and to spread throughout the print area. Then, a means for filling the toner with a constant pressure into the inside thereof and stopping the supply when a certain pressure is reached was constructed. FIG. 9 is a diagram illustrating a pressure distribution inside the pressure container in which the toner is statically enclosed. As shown, the pressure distribution is constant inside the confined vessel.

According to the toner supply system of the present invention for supplying a non-volatile high-viscosity, high-concentration liquid toner to a developing roller, the liquid toner is supplied to the developing roller by rotating while being in contact with the developing roller. A supply roller for supplying;
Supply means for supplying liquid toner to the surface of the supply roller. The supply means has a length exceeding the width in the width direction of the supply roller, a width covering a part of the supply roller in a circumferential direction, and is arranged with a space between the supply roller and the surface thereof. And a toner supply tray having the space sealed, and configured to supply liquid toner to the space. Further, a manual operation for detecting the pressure inside the space is provided, and the supply is stopped by detecting an increase in the pressure inside the container due to the supply of the toner. As a result, even if the viscosity of the toner varies extremely depending on the shear rate, the toner can be reliably supplied to the entire area.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail according to embodiments. FIG. 1 shows the overall configuration of an electrophotographic apparatus using a liquid toner to which the present invention can be applied. As illustrated, the electrophotographic apparatus includes, as main components, a photoconductor, a charger, an exposure device, a developing machine for each color (only two are shown), an intermediate transfer body IMR, and a backup roller. .

The charger charges the photoreceptor to about 700V. The exposure apparatus exposes the photoreceptor using a laser beam having a wavelength of 780 nm, so that the potential of the exposed portion becomes about 10
An electrostatic latent image of 0 V is formed on the photoconductor.

The developing machines are usually provided in association with yellow / magenta / cyan / black and have a developing device of about 400 V (E
1) and the toner viscosity is 400 to 40
Using a liquid toner having a carrier viscosity of 20 cSt at 00 mPa · S, a toner layer having a thickness of 2 to 3 μm is formed on the developing roller. The developing roller supplies the toner particles, which are positively charged, to the photosensitive member according to the electric field between the photosensitive member and the toner. Attach the particles.

The intermediate transfer member IMR is about -800 V (E
2) biased according to the electric field between the photoreceptor and
The toner attached to the photoconductor is transferred. The intermediate transfer member IMR firstly transfers, for example, yellow toner adhered to the photoreceptor, subsequently transfers magenta toner adhered to the photoreceptor, and subsequently transfers cyan toner. Then, the black toner is transferred.

The toner attached to the intermediate transfer member IMR is
It is heated and melted by a heating device (not shown). The backup roller transfers the fused toner on the intermediate transfer member IMR to a print medium and fixes it.

FIGS. 2 to 4 are diagrams illustrating the configuration of supplying toner to the developing roller. FIG. 2 is a cross-sectional view showing the entire toner supply configuration, FIG. 3 is a view showing only the seal taken out of the toner supply configuration shown in FIG. 2, and
FIG. 4 is a diagram for explaining toner circulation.

The surface of the developing roller is supplied from a patterned roller whose surface moves in the same direction at the contact portion. The patterned roller (for example, an Asahi roll anilox roller) is used to form, for example, an oblique groove-like line having an angle with respect to the circumferential direction at a rate of 100 to 3 per inch.
This is a roller having a fine pattern in which 50 lines are provided, or a grid is formed by further adding lines in a direction intersecting the lines. By conveying using the grooves of such a patterned roller, it is possible to supply a fixed amount of toner limited only by the number of grooves and the size (cross-sectional area) of the grooves. Note that a region surrounded by the groove is called a cell. The supply of the toner to the patterned roller is performed from the toner in the toner supply tray. The toner supply tray is
As shown in the drawing, the pattern roller has a length exceeding the width direction length and a width covering a part of the pattern roller in the circumferential direction, and a space is provided between the pattern roller and the surface of the patterned roller. In addition to the arrangement, the space is sealed. By supplying the liquid toner to this space, the toner is supplied from there to the surface of the patterned roller.

In other words, the patterned rollers are arranged in such a positional relationship as to cover the opening of the toner supply tray. Further, the space is sealed from the front, rear, left and right in the gap around the patterned roller by a seal as shown in FIG. 2 or FIG. Then, the toner supply tray is pressed against the patterned roller using an elastic body such as a spring in a direction against the internal toner pressure.

However, if the seal is merely performed, the internal pressure rises due to the excessive supply of the toner, and the internal pressure increases. If the toner is excessively supplied or inclined when the patterned roller is used as the supply roller, the internal pressure increases. The toner may seep out from between the cells of the leveling blade and the patterned roller, where a toner pool may be formed, which may affect the next printed image. Furthermore, in the method in which the toner is stored on the supply tray, stagnation of the toner occurs over time,
It also has an adverse effect on image quality.

Then, by detecting the pressure inside the space,
Controls toner supply. As the pressure detecting means, for example, an optical sensor including a light emitting diode and a photodiode can be used. In the illustrated float type optical sensor, a hose (only a part is shown) is connected to a hole formed at an appropriate position of the toner supply tray so as to detect a pressure inside the toner supply tray. When the pressure inside the toner supply tray rises, the float shown rises, and then the float tip is configured to block the light path composed of the light emitting diode and the photodiode. It is possible to control to stop the toner supply to the toner supply tray by turning off the optical signal. As described above, by providing the means for detecting the pressure increase inside the container due to the supply of the toner and stopping the supply, it is possible to supply only the toner necessary for printing.

The horizontal seals 1-3 for hermetically sealing the toner supply tray will be further described with reference to FIG. Among the openings formed between the toner supply tray and the patterned roller, the seal 1 and the seal 2 seal the front-back direction, and the seal 3 seals from the left-right direction. The seal 3 is formed in a sheet shape and inserted between a rotating portion of the patterned roller and fixed flanges located on both sides thereof and supporting the rotating portion. By applying sealing force to the toner in the roller width direction by such sealing, the filling of the toner in the container can be ensured.

As a material for the seal, urethane rubber having a hardness of 60 ° or less can be used in order to guarantee abrasion resistance and sealing accuracy. Further, as a material for the seal, a sponge can be used to ensure sealing accuracy. However, in this case, it is desirable to use a sponge of independent foaming in order to prevent toner seepage. In addition, as a material for the seal, a polyester sheet having little friction with the roller can be used.

On the patterned roller, a leveling blade is provided on the outlet side from the toner supply tray, and is mounted on the patterned roller at a constant pressure by spring elasticity. Thus, the toner can be uniformly conveyed and supplied onto the developing roller.

Next, toner circulation will be described with reference to FIG. As shown in the figure, a discharge port for flowing toner is provided on both sides of the toner supply tray, and a supply port is provided from the center. The pressure of the supply unit due to the toner injection is detected, and when the pressure of the supply unit exceeds a certain pressure, the toner is discharged from the discharge port and the pressure is kept constant. The excessively discharged toner is returned to the toner bottle and circulated, so that the amount of consumed toner can be reduced. in this way,
The toner can be supplied to the developing roller over a wide area by injecting the toner from the center of the toner supply tray and using the fluidity of the liquid toner and the rotation of the transport roller. In addition to the gap between the patterned roller and the supply tray as a toner passage in the toner supply tray, a groove can be dug in the width direction of the roller at the bottom of the supply tray to provide a structure in which the fluidity of the toner is further improved. .

FIG. 5 is a diagram illustrating the configuration of the toner supply tray. In the example shown in the drawing, the section is formed in an arc shape, and is arranged so as to form a constant gap with the patterned roller. As shown in the drawing, the toner supply does not necessarily have to be performed from the center of the supply tray. At the bottom or side.

The electrophotographic apparatus has a developing device for each color and a toner supply structure for each color, and it is necessary to mount these devices in a narrow space. For this reason, it is difficult to mount the entire toner supply tray horizontally below the toner supply roller. In the present invention, the toner is circulated in order to eliminate the stagnation of the toner, and not only is the toner supplied uniformly and stably to the developing roller, but also the sealing property of the supply roller and the toner supply tray that supplies the toner stably to the developing roller is improved. For this reason, the supply tray can be attached at any position by being inclined as shown in FIG. by this,
The size of the device can be reduced.

When a patterned roller is used, leakage from the cell and the leveling blade is prevented by
By preparing another blade on the downstream side in the rotation direction as shown in FIG. 7, the toner leaking from the cells of the patterned roller can be scraped and the effect on the image quality can be prevented.

Further, when a patterned roller having cells is used as a supply roller, toner leaking from the leveling blade is also returned to the toner tank and circulated to minimize toner consumption. Can be.

Further, the patterned roller controls the rotation start timing to rotate alone from before the start of printing, so that the toner leaking from between the leveling blade and the patterned roller cell is removed after a predetermined time by the developing roller. , And can be configured to be removed by a collecting blade of the developing roller.

[0034]

According to the present invention, by sealing the supply roller and the supply tray, the arrangement angle of the developing machine with respect to the photoreceptor is widened, and the degree of freedom of the apparatus configuration can be increased.

According to the present invention, by circulating the toner supply, the pressure in the supply tray is prevented from rising, the toner is prevented from leaking from an elastic seal such as rubber or sponge, and the stagnation of the toner is eliminated, and the unevenness of the image quality is prevented. Can be eliminated.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an electrophotographic apparatus using a liquid toner to which the present invention can be applied.

FIG. 2 is a cross-sectional view illustrating the entire toner supply configuration.

FIG. 3 is a diagram illustrating only a seal taken out of the toner supply configuration illustrated in FIG. 2;

FIG. 4 is a diagram for explaining toner circulation.

FIG. 5 is a diagram illustrating an example of a toner supply tray.

FIG. 6 is a diagram illustrating an example in which a toner supply configuration is attached at an angle.

FIG. 7 is a diagram illustrating an example of a toner supply configuration including another blade.

FIG. 8 is a diagram showing a toner supply method proposed by the present applicant earlier.

FIG. 9 is a diagram showing a pressure distribution inside a pressure container in which toner is statically enclosed.

FIG. 10 is a diagram showing the viscoelastic behavior of a high-viscosity, high-concentration liquid toner.

FIG. 11 is a diagram showing a velocity profile when liquid toner advances inside a tube tube.

FIG. 12 (a) A state of blowing Newtonian fluid,
(B) is a diagram showing a state of blowing out a non-Newtonian fluid.

[Description of Signs] 10 Photoconductor 11 Toner supply port 15 Developing roller 16 Applicator roller 17 Applicator roller 18 Guide frame

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hongo 98 Unoki-nu 98, Unoki-cho, Kawakita-gun, Ishikawa Pref. 2 Inside PFU Co., Ltd. (72) Masataka Takahata 98 Uno-nu 98, Unoki-cho, Kawakita-gun, Ishikawa No. 2 in PFU Co., Ltd. (72) Inventor Motoharu Ichida Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa 98-2 Inventor P72 Co., Ltd. (72) Inventor Yasuhiko Kishimoto Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa 98-2, PFU Co., Ltd. (72) Inventor Tatsuo Nozaki, Unoki-cho, Kawakita-gun, Ishikawa Pref. 98 98-2 PFM Co., Ltd. (72) Inventor, Masanobu Motoe Unoki, Unoki-cho, Kawakita-gun, Ishikawa No. 98 2 PFU Co., Ltd. (72) Inventor Yutaka Nakajima No. 98 Unoki Nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture No.2 Inside PFU Co., Ltd. (72) Inventor Tadashi Nishikawa 98, Unoki-nu, Unoki-cho, Hebei-gun, Ishikawa Pref. Inside (72) Inventor Akihiko Inamoto 98, Unoki-nu, Unoki-cho, Kawakita-gun, Ishikawa Prefecture (2) Inventor Satoshi Miyamoto 98 Uno-kinu, Unoki-cho, Kawakita-gun, Ishikawa Pref. F-term (reference) 2H074 AA03 BB02 BB06 BB32 BB65 BB71 EE07

Claims (15)

[Claims] 1. A toner supply system for an electrophotographic apparatus for supplying a non-volatile, high-viscosity, high-concentration liquid toner to a developing roller, wherein the liquid toner is supplied to the developing roller by rotating while being in contact with the developing roller. A supply roller for supplying the liquid toner to a surface of the supply roller, the supply means including: a length exceeding the width of the supply roller in a width direction; A toner supply tray that has a width covering the portion and is spaced from the surface of the supply roller, and is provided with a toner supply tray in which the space is sealed to supply liquid toner to the space. And a control means for detecting a pressure increase in the container due to the supply of toner and controlling the supply to be stopped. Method. 2. The toner supply system according to claim 1, wherein the sealing of the space is performed by a seal provided on the toner supply tray around the space. 3. The toner supply system according to claim 1, wherein urethane rubber having a hardness of 60 ° or less is used as a material of the seal. 4. The toner supply method for an electrophotographic apparatus according to claim 1, wherein a closed-cell sponge is used as a material of the seal. 5. The toner supply system according to claim 1, wherein a polyester sheet having a small friction with a roller is used as a material of the seal. 6. The toner supply system according to claim 1, wherein the manual operation for detecting the pressure inside the space is a float-type optical sensor mounted on a toner supply tray. 7. The toner supply tray according to claim 1, wherein a discharge port through which the toner flows is provided at a side portion of the toner supply tray, and the toner is discharged from the discharge port when the supply section has a predetermined pressure or more, and the pressure is kept constant. Toner supply system for electrophotographic apparatus. 8. The toner supply method of an electrophotographic apparatus according to claim 7, wherein the toner discharged from said discharge port is returned to a toner supply bottle and circulated to reduce the toner consumption. 9. The electronic device according to claim 7, wherein the toner is supplied from a central portion of the toner supply tray, and the toner is supplied to the developing roller over a wide area using the fluidity of the liquid toner and the rotation of the transport roller. A toner supply system for photographic devices. 10. Injecting toner from the side of the toner supply tray and discharging the toner from the other side, and using the fluidity of the liquid toner and the rotation of the conveying roller, the toner is spread over a wide area to the developing roller. A toner supply method for an electrophotographic apparatus according to claim 7. 11. The toner supply system according to claim 1, wherein a leveling blade for uniformly transporting and supplying the toner is mounted on the supply roller at a constant pressure by spring elasticity. 12. The apparatus according to claim 1, wherein a patterned roller is used as the supply roller, and a blade for scraping off toner leaking from between the leveling blade and the patterned roller cell by a toner supply pressure is provided on the downstream side. Toner supply system for electrophotographic apparatus. 13. The toner supply method for an electrophotographic apparatus according to claim 12, wherein the toner scraped by said blade is returned to a toner tank and circulated to minimize toner consumption. 14. A patterning roller is used as the supply roller, and before the start of printing, the patterning roller is rotated alone, and toner leaking from between the leveling blade and the patterned roller cell is transferred to a developing roller. 2. The toner supply system for an electrophotographic apparatus according to claim 1, wherein a rotation start timing for removing the roller by a collection blade is controlled. 15. The toner supply method for an electrophotographic apparatus according to claim 1, wherein a groove is formed in the bottom of the toner supply tray in the width direction to further enhance the fluidity of the toner.