Treatment agent liquid application device for ink jet printer

A treatment agent liquid application device for an ink jet printer includes a supply pan including a liquid chamber that stores treatment agent liquid; an application roller that applies the treatment agent liquid on a record surface of a recording medium; a squeeze roller that rotates to draw up a part of the treatment agent liquid in which a part of the squeeze roller is immersed in the supply pan and to supply the treatment agent liquid to a pressure contact part between the application roller and the squeeze roller; and a partition member arranged outside the squeeze roller and along a circumferential direction of the squeeze roller in the supply pan, the partition member dividing the liquid chamber in the supply pan into a liquid chamber on a squeeze roller side and an external liquid chamber outside the liquid chamber on the squeeze roller side.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosures herein generally relate to a treatment agent liquid application device for an ink jet printer. The disclosures, in particular, relate to a treatment agent liquid application device for an ink jet printer that applies a treatment agent such as a blurring inhibitor that inhibits an image blurring in the ink jet printer, which makes ink droplets impact onto an recording medium such as a paper, for example, to form an image, onto a recording surface prior to the image formation.

2. Description of the Related Art

Recently, ink jet printers have rapidly become widespread, since an image formation by an ink jet type has advantages of a low noise, a low running cost and a function of color printing. Such ink jet printers include a serial printer and a line printer. The serial printer prints an image by combining a movement in a main scanning direction in which ink droplets are discharged while a record head moves in the main scanning direction (a width direction of the recording medium) and a movement of the rewording medium in a sub scanning direction. The line printer is provided with a line head having a print width for the width of the recording medium, and prints while moving the line head and the recording medium relatively.

The line printer includes a continuous paper printer which uses a continuous paper as a recording medium, which is suitable for large amounts of printing. The continuous paper printer prints while conveying continuous paper wound in a roll at high speed (for example, 0.5 to 2 m/s).

On the other hand, there is an ink jet printer having a configuration of printing both sides of a continuous paper, from a standpoint of resource saving, by a tandem operation using two continuous paper printers, i.e. printing a first side of the continuous paper (for example, top side) by the first continuous paper printer, inverting the continuous paper, and printing a second side of the continuous paper (for example, back side) by the second continuous paper printer.

Recently, in the above-described ink jet printers, image quality becomes higher and higher, since a discharge timing of an ink droplet and a size of an ink droplet can be finely controlled. However, in the ink jet printer, ink droplets are discharged to form an image, and until the ink droplets are dried, impacted dots blur along a paper fiber. Accordingly, a phenomenon such as feathering or color bleed, in which a color border becomes blurred by mixing with an adjacent ink droplet with different color, easily occurs, and the quality of an image degrades.

As a method of inhibiting the degradation of the quality of the image, there is the art of applying treatment agent liquid such as a blurring inhibitor on the recording medium as a preprocessing, so as to inhibit the blurring of ink by aggregating a component of pigment in the ink droplet.

Such kind of treatment agent liquid application device as above includes a supply pan that stores the treatment agent liquid, an application roller that applies the treatment agent liquid on a record surface of the recording medium, a squeeze roller that draws up the treatment agent liquid in the supply pan, thins the treatment agent liquid and transfers it to the application roller, a pressure roller that conveys the recording medium while holding it with the application roller, and the like.

In the treatment agent liquid application device as described above, it is proposed that in order to remove a foreign matter such as paper dust attached on a surface of the squeeze roller, a swirling current with high flow velocity is generated in the supply pan, and a partition which is orthogonal to a rotational direction of the squeeze roller is provided.

Moreover, it is proposed that in order to prevent the treatment agent liquid in the supply pan from evaporating, the treatment agent liquid, the squeeze roller and the application roller are housed in the supply pan (housing).

For example, Japanese Published Patent Applications No. 2012-238374 and 2012-56261 disclose the treatment agent liquid application device described as above.

In the treatment agent liquid application device of the related art, when the treatment agent liquid is drawn up by rotating the squeeze roller a part of which is immersed in the treatment agent liquid in the supply pan, a position of fluid level varies greatly, and a liquid amount of the treatment agent liquid in the supply pan may not be detected correctly.

Accordingly, an uneven application or an application failure may occur due to an insufficient supply of the treatment agent liquid, and the function of the treatment agent liquid cannot be fulfilled. Moreover, contrary to the above, due to an excess in supply of the treatment agent liquid, the treatment agent liquid overflows from the supply pan into the application device and a liquid dispersion occurs. Accordingly, a problem that the inside of the application device is smeared or an electric part is damaged will occur.

The shortage of supply or the excess in supply of the treatment agent liquid, described as above, depends on a speed of application of the treatment agent liquid. Particularly, for the application device in which plural application speeds are set, it is necessary to be careful so that the shortage of supply or the excess in supply of the treatment agent liquid does not occur for each of the application speeds.

Moreover, the shortage of supply or the excess in supply also depends on a viscosity of the treatment agent liquid. It is necessary to respond to a change in the viscosity of the treatment agent liquid associated with water evaporation. Particularly, for the application device using plural kinds of treatment agent liquids, changes in viscosity characteristic of which are different from each other, the above-described problem becomes complicated.

Japanese Published Patent Applications No. 2012-218374 and 2012-56261 do not disclose suppressing the variation of the position of the fluid level which occurs when the treatment agent liquid is drawn up by the squeeze roller rotating, and resolving the problem due to the shortage of supply or the excess in supply of the treatment agent liquid.

SUMMARY OF THE INVENTION

It is a general object of at least one embodiment of the present invention to provide a treatment agent liquid application device for an ink jet printer that substantially obviates one or more problems caused by the limitations and disadvantages of the related art.

In one embodiment, a treatment agent liquid application device for an ink jet printer includes a supply pan including a liquid chamber that stores treatment agent liquid; an application roller that applies the treatment agent liquid on a record surface of a recording medium; a squeeze roller that rotates to draw up a part of the treatment agent liquid in which a part of the squeeze roller is immersed in the supply pan and to supply the treatment agent liquid to a pressure contact part between the application roller and the squeeze roller; and a partition member arranged outside the squeeze roller and along a circumferential direction of the squeeze roller in the supply pan, the partition member dividing the liquid chamber in the supply pan into a liquid chamber on a squeeze roller side and an external liquid chamber outside the liquid chamber on the squeeze roller side.

The treatment agent liquid application device according to the present invention includes a liquid chamber on a squeeze roller side and a liquid chamber on an external side which are separated from each other, and a variation of the treatment agent liquid due to a rotation of a squeeze roller can be prevented from transmitting to the liquid chamber on the external side. Therefore, the problem due to the variation of the treatment agent liquid is resolved. According to the present invention, a treatment agent liquid application device for an ink jet printer with a good operation reliability, which can apply the treatment agent liquid properly and in which neither a shortage of supply nor an excess in supply of the treatment agent liquid for a recording medium occurs, can be provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 5is a flowchart illustrating a schematic configuration of an image forming system according to the first embodiment.

As shown inFIG. 5, a recording medium W including an elongated continuous paper reeled out from a paper feed device100is, at first, sent into a treatment agent liquid application device101, and a preprocessing is performed by applying a treatment agent liquid such as an inhibitor on a surface of the recording medium W.

Next, the processed recording medium W is sent into an ink jet printer102. A desired image is formed by discharging ink droplets onto the surface of the recording medium W. Then, the recording medium W is sent into a post-processing device103, and a predetermined processing is performed for the recording medium W.

A speed of application of the treatment agent liquid in the above-described system can be arbitrarily set in a range from 50 m/min to 150 m/min.

FIG. 1is a diagram illustrating a schematic configuration of the treatment agent liquid application device101used in the above-described image forming system according to the present embodiment, and shows a state of applying the treat agent liquid.

The treatment agent liquid application unit101includes a supply pan2that stores the treatment agent liquid1, an application roller3that applied the treatment liquid1on a record surface of the recording medium W, a squeeze roller4that draws the treatment agent liquid1from the supply pan2, thins the treatment agent liquid and transfers it to the application roller3, a pressure roller5that conveys the recording medium W while holding it with the application roller3, and the like.

A component of the treatment agent liquid1is arbitrarily selected taking account of, for example, a component of ink used in the ink jet printer102, a material of the recording medium W, or the like.

To a side plate of the supply pan2, a base end section of an arm6is connected. To a free end section of the arm6, a pin8is attached via a compression spring7. The pin8elastically contacts with a periphery of an eccentric cam9by a restitution force of the compression spring7.

The squeeze roller4is rotatably supported by the side plate of the supply pan2, though it is not shown in figures, and faces the application roller3which is arranged on the upper side. According to a rotation of the eccentric cam9, a pressure force from the compression spring7changes, and the whole supply pan2oscillates around an oscillation pin10as a support point. Along with the oscillation, a position of the squeeze roller4is also changed. A state shown inFIG. 1is an application state where the squeeze roller4is pressed to contact the application roller3.

In the supply pan2, a predetermined amount of treatment agent liquid is fed. The amount of liquid is monitored by a fluid level sensor11provided on the side plate of the supply pan2. Approximately the lower half of the squeeze roller4is immersed in the treatment agent liquid1.

The application roller3and the squeeze roller are coupled by a gear, which is not shown, by a motor12which rotationally drives the application roller3. The application roller3and the squeeze roller4rotate synchronously. Then, the treatment agent liquid1is drawn up by the rotation of the squeeze roller4. Excess treatment agent liquid is scraped off by a blade17which contacts a periphery of the squeeze roller4in a sliding fashion.

A predetermined amount of the treatment agent liquid1is conveyed to a nip portion between the squeeze roller4and the application roller3. By the treatment agent liquid1passing through the nip portion a thin film of the treatment agent liquid1which is formed in an infinitesimally uniform manner on the surface of the application roller3.

The pressure roller is supported at a free end of a turning arm13rotatably, and to a base end of the turning arm13an extension spring14is connected. An intermediate part of the turning arm13is supported by an oscillation pin15. An eccentric cam is in contact with a side of the turning arm13. By rotating the eccentric cam16, the pressure roller5can be separated from the application roller3against a tensile force by the extension spring14.

By pressing the recording medium against the application roller3by the pressing roller5, the thin film of the treatment agent liquid1supported on the application roller3is transferred to and applied onto the recording medium W.

To the supply pan2, a supply tank24is connected via a feed pipe23. On the feed pipe23, a feed valve25and a feed pump26are arranged. The fluid level sensor11that monitors a fluid level of the treatment agent liquid1in the supply pan2is arranged at a position where a fluid level in an external liquid chamber, which will be described later, in the supply pan2can be detected.

The supply tank24includes a cartridge which is highly airtight filled with the new treatment agent liquid1; a reservoir tank which is more airtight than the supply pan2, retracts the treatment agent liquid1from the supply pan2and stores it when the application of the treatment agent liquid is not performed for a long period of time, and returns the treatment agent liquid1to the supply pan2when the treatment agent liquid is used; or both the cartridge and the reservoir tank.

When the fluid level of the treatment agent liquid1lowers due to the use of the treatment agent liquid1, the fluid level sensor11detects it, by opening the feed valve25and activating the feed pump26, the treatment agent liquid1in the supply tank24is sent into the supply pan2(external liquid chamber20) through the feed pipe23.

When the fluid level reaches a desired position, by closing the feed valve25and stopping the activation of the feed pump26, a constant fluid level of the treatment agent liquid1in the supply tank24is maintained. In the present embodiment, the treatment agent liquid1is filled up to a level around a rotation center of the squeeze roller4, as shown inFIG. 1.

Moreover, taking in account the degradation or property due to a thickening or the like of the treatment agent liquid1, in order to gradually eject the treatment agent liquid1to the outside of the system, a waste tank28is connected to the supply pan2via an exhaust pipe27. On the exhaust pipe27, an exhaust valve29and an exhaust pump30are arranged.

By opening the exhaust valve29and activating the exhaust pump30, the degraded treatment agent liquid1in the supply tank24is ejected into the waste tank28through the exhaust pipe27.

Between the supply pan2and the squeeze roller4, and at a position near the squeeze roller, a partition member18having an approximately U-shaped cross section is arranged along a circumferential direction of the squeeze roller4. Both end portions of the partition member18are projected upward from the fluid level of the treatment agent liquid1. According to the arrangement of the partition member18, the liquid chamber in the supply pan2has a configuration including two liquid chambers in which a liquid chamber19on the squeeze roller side surrounding a lower part of the squeeze roller4is separated (divided) from an external liquid chamber20outside the liquid chamber19.

A volume V2of the external liquid chamber20is greater than a volume V1of the liquid chamber19on the squeeze roller side, i.e. V1<V2. More specifically, the volume V2of the external liquid chamber20is more than five times greater than the volume V1of the liquid chamber19on the squeeze roller side. In the present embodiment, the volume V2is ten times the volume V1, i.e. V2=V1*10. Meanwhile, on the partition member18, plural though holes22are formed so that the treatment agent liquid1can be input to/output from the liquid chamber19on the squeeze roller side from/to the external liquid chamber20.

Meanwhile, a diameter of the through hole22is determined taking in account the damper effect of the treatment agent liquid1passing through the through hole22.

According to the partition member18, a laminar flow generated in the liquid chamber19on the squeeze roller side by the rotation of the squeeze roller is prevented from travelling to the external liquid chamber20. Furthermore, according to the damper effect by the treatment agent liquid flowing between the liquid chamber19on the squeeze roller side and the external liquid chamber20, a variation of the fluid level in the external liquid chamber20can be prevented or suppressed.

Accordingly, the fluid level sensor11can always detect a proper fluid level, and can remove the insufficient supply of the treatment agent liquid1or the excess in supply of the treatment agent liquid.

Moreover, above the liquid chamber19on the squeeze roller side and on a downstream side of the rotational direction of the squeeze roller4, the blade17is provided which is pressed in contact with the periphery of the squeeze roller4. The blade prevents the variation of the fluid level due to an excess drawing of the treatment agent liquid1.

The blade17includes a plate having a rectangular shape. The blade17is curved, and a curved surface of the blade17, not an edge part of the blade17, is pressed in contact with the periphery of the squeeze roller4.

The curved surface contacts the periphery of the squeeze roller4in order to ensure a stable amount of supply of the treatment agent liquid1irrespective of a number of revolutions of the squeeze roller4. In the case where the edge part of the blade17is pressed in contact with the periphery of the squeeze roller4a state of pressing of the edge part into the squeeze roller4changes depending on the number of revolutions of the squeeze roller4.

In order to return the excess treatment agent liquid1scraped off by the blade to the external liquid chamber20from a space31above the blade17, a passing flow path32is provided. In the present embodiment, the passing flow path32includes a through hole formed on an overlapping part of the partition member18and the blade17or a top edge part of the overlapping part of the partition member18and the blade17. Moreover, the passing flow path32includes a groove formed in the top edge of the overlapping part of the partition member18and the blade17.

According to the passing flow path32formed as above the excess treatment agent liquid does not accumulate in the space31above the blade17, and a scattering or an overflow of the treatment agent liquid1is prevented.

The blade17includes an elastic body such as, for example, a polyethylene resin sheet. A load of pressure contact of the blade with the squeeze roller4is set to greater than or equal to 2 kgf/m, which is sufficient for preventing an excess passing of the treatment agent liquid1. As described above, by using the blade17including the elastic body and by setting the load of pressure contact as above, an accuracy of a part of the blade is relaxed. A strict adjustment becomes unnecessary, and a device conserving a space and with a low cost is provided.

As shown inFIGS. 3 and 4, on a surface of the squeeze roller4, large numbers of grooves33having a depth greater than 5 mm are formed along the circumferential direction of the squeeze roller4. According to the grooves, an excess passing of the treatment agent liquid1due to an uplifting of the blade17associated with the number of revolutions of the squeeze roller or a viscosity of the treatment agent liquid1can be prevented.

FIG. 4is an enlarged sectional view of a part, denoted by “X” inFIG. 3, of the squeeze roller4used in the treatment agent liquid application device according to the first embodiment, shown inFIG. 3. As shown inFIG. 4, the groove33formed on the surface of the squeeze roller4has a cross section of a shape of which is a form of a wave.

In the present embodiment, the supply pan2is divided into two liquid chambers, i.e. the liquid chamber19on the squeeze roller side and the external liquid chamber20, by the partition member18. However, plural partition members may be provided to divide the supply pan2into three or more liquid chambers. By dividing into three or more liquid chambers, the effect of suppressing a variation of a fluid level can be further improved, and it is an effective configuration for a specification where the number of revolutions of the squeeze roller4becomes larger and the fluid level varies enormously.

In the present embodiment, a treatment agent liquid application device for an ink jet printer includes a supply pan; an application roller; and a squeeze roller. A liquid chamber in the supply pan is divided into a liquid chamber on a squeeze roller side and an external liquid chamber outside the liquid chamber on the squeeze roller side by a partition member arranged along a circumferential direction of the squeeze roller.

Since the liquid chamber is divided into two or more tanks, i.e. the liquid chamber on the squeeze roller side and the external liquid chamber, a variation of the treatment agent liquid in the liquid chamber on the squeeze roller side due to a rotation of the squeeze roller can be prevented from travelling to the external liquid chamber, and a problem due to the variation of the treatment agent liquid, for example, a scattering of the treatment agent liquid, is resolved.

Moreover, the treatment agent liquid application device according to the present embodiment includes a fluid level sensor that detects a position of a fluid level of the treatment agent liquid in the external liquid chamber. According to the above feature, the position of the fluid level (amount of liquid) can be detected in the external liquid chamber in which the fluid level is stable.

In the treatment agent liquid application device according to the present embodiment, a through hole is provided in the partition member through which the treatment agent liquid flows from/into the liquid chamber on the squeeze roller side into/from the external liquid chamber. According to a damper effect of the treatment agent liquid flowing through the through hole, the flow of the treatment agent liquid in the liquid chamber on the squeeze roller side is suppressed, and the scattering of the treatment agent liquid or the like can be prevented.

In the treatment agent liquid application device according to the present embodiment, an upper end portion of the partition member is projected upward from the fluid level of the treatment agent liquid in the supply pan. Then, the liquid chamber is definitely divided by the partition member.

In the treatment agent liquid application device according to the present embodiment, a volume of the external liquid chamber is set so as to be greater than a volume of the liquid chamber on the squeeze roller side. Accordingly, the damper effect by the treatment agent liquid flowing through the through hole in the partition member is exerted more effectively, and the variation of the treatment agent liquid in the liquid chamber on the squeeze roller side is definitely suppressed.

In the treatment agent liquid application device according to the present embodiment, the volume of the external liquid chamber is more than five times greater than the volume of the liquid chamber on the squeeze roller side. Accordingly, the damper effect by the treatment agent liquid flowing through the through hole in the partition member is exerted more effectively, and the variation of the treatment agent liquid in the liquid chamber on the squeeze roller side is definitely suppressed.

In the treatment agent liquid application device according to the present embodiment, above the liquid chamber on the squeeze roller side, a blade pressed in contact with a periphery of the squeeze roller is provided. Accordingly, a variation of the fluid level due to an excess drawing of the treatment agent liquid by the squeeze roller is prevented.

In the treatment agent liquid application device according to the present embodiment, a flow path through which the treatment agent liquid can flow from a space above the blade to the external liquid chamber is provided. Accordingly, excess treatment agent liquid does not accumulate in the space above the blade, and a scattering or an overflow of the treatment agent liquid is prevented.

In the treatment agent liquid application device according to the present embodiment, the blade includes a plate having a rectangular shape. The blade is curved, and a curved surface of the blade, not an edge part of the blade, is pressed in contact with a periphery of the squeeze roller. A difference in a state of pressing of the blade into the squeeze roller due to a number of revolutions of the squeeze roller can be removed, and an amount of drawing up of the treatment agent liquid becomes stable. Furthermore, an uneven application, an application failure, an overflow of the treatment agent liquid, dispersion or the like can be prevented.

In the treatment agent liquid application device according to the present embodiment, a load of pressure contact of the blade with the squeeze roller is set greater than or equal to 2 kgf/m. Accordingly, the difference in the state of pressing of the blade Into the squeeze roller due to the number of revolutions of the squeeze roller can be removed, and the amount of drawing of the treatment agent liquid becomes stable. Furthermore, an uneven application, an application failure, an overflow of the treatment agent liquid, dispersion or the like can be prevented.

In the treatment agent liquid application device according to the present embodiment, a groove is formed on the periphery of the squeeze roller along a circumferential direction of the squeeze roller. Accordingly, an excess passing of the treatment agent liquid due to an uplifting of the blade associated with the number of revolutions of the squeeze roller or a viscosity of the treatment agent liquid can be prevented.

In the treatment agent liquid application device according to the present embodiment, the treatment agent liquid is a blurring inhibitor that inhibits a blurring of ink on a recording medium. Accordingly, a clear image without a blurring irrespective of a kind of the recording medium can be obtained.

Further, the present invention is not limited to these embodiments, but various variations and modifications ay be made without departing from the scope of the present invention.

The present application is based on and claims the benefit of priority Japanese Priority Application No. 2013-151917 filed on Jul. 22, 2013, the entire contents of which are hereby incorporated by reference.