JP7213673B2 - Mist collection device - Google Patents

Description

The present invention relates to a mist collection device that reduces the risk of contact with paper while achieving high mist collection efficiency.

2. Description of the Related Art Inkjet image forming apparatuses are generally well known, which eject ink droplets from an inkjet head to perform printing on a printing medium. Such an inkjet printing apparatus is equipped with a conveyor belt that conveys the print medium below the inkjet head, and conveys the print medium at a predetermined conveyance speed while sucking the print medium onto the conveyor belt with a suction fan installed in the conveyor belt. On the other hand, there is a full-line type that prints with ink ejected from an inkjet head.

When the print medium is conveyed at a predetermined conveying speed while being sucked onto the conveying belt, an air current is generated along the conveying direction of the print medium. At this time, minute droplets (mist) generated by the ink discharge and not used for image formation are swept away by this air current. The flowed mist lands in places that are out of alignment with the ejection position, such as in the transport path, causing ink stains to accumulate inside the machine, and the accumulated ink is transferred to the paper, causing deterioration in the image quality of the printing paper. There was something that happened.

Japanese Unexamined Patent Application Publication No. 2002-100002 discloses a technique related to a device for ejecting liquid droplets, in which a mist collecting member 115 is disposed on the opposite side of the moving direction of the carriage 100 .

JP 2017-109490 A

However, in the technique described in Patent Document 1, the mist collecting member 115 is disposed on the opposite side of the moving direction of the carriage 100, so the positions of the mist collecting member 115 and the paper are always constant. In order to collect the mist entrained in the airflow generated by the conveyed paper, the closer the mist collecting member is to the paper, the higher the collection efficiency becomes. On the other hand, the closer the mist collecting member is to the paper, the higher the probability that the mist collecting member comes into contact with the paper.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mist collecting device that reduces the risk of contact with paper while achieving high mist collection efficiency.

In order to achieve the above object, the features of the mist collection device according to the present invention are:
A mist collecting device for collecting mist generated when ink is ejected from an inkjet head onto a printing medium conveyed on a conveying path,
a conveying means for conveying the print medium along the conveying path;
a charging member that is provided downstream of the inkjet head and above the conveying means and that is charged;
an elevating mechanism for elevating the charging member with respect to the conveying means;
It has been prepared.

According to the characteristics of the mist collection device according to the present invention, it is possible to reduce the risk of paper contact while achieving high mist collection efficiency.

1 is a configuration diagram showing the configuration of an inkjet printing apparatus that is an embodiment of the present invention; FIG. 1 is an enlarged side view of a printing unit included in an inkjet printing apparatus that is an embodiment of the present invention; FIG. 1 is a diagram showing the functional configuration of an inkjet printing apparatus that is an embodiment of the present invention; FIG. It is the figure which showed an example of the gap adjustment table memorize|stored in ROM with which the inkjet printing apparatus which is one Example of this invention was equipped. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing explaining the effect|action of the inkjet printing apparatus which is one Example of this invention. 4 is a flow chart showing the processing contents of the inkjet printing apparatus that is one embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent reference numerals are attached to the same or equivalent parts and components throughout each drawing. However, it should be noted that the drawings are schematic and differ from reality. In addition, there are portions with different dimensional relationships and ratios between the drawings.

Further, the embodiments shown below are examples of apparatuses and the like for embodying the technical idea of the present invention. not specific to The technical idea of this invention can be modified in various ways within the scope of claims.

An embodiment of an inkjet printer to which a mist collection device according to the present invention is applied will be described in detail below with reference to the accompanying drawings.

(Overall Configuration of Inkjet Printing Device)
A configuration of an inkjet printing apparatus 1 that is an embodiment of the present invention will be described in detail. FIG. 1 is a configuration diagram showing the configuration of an inkjet printer 1 that is an embodiment of the present invention.

As shown in FIG. 1, the inkjet printing apparatus 1 is an image forming apparatus that forms an image on a sheet of paper P, which is a printing medium that is conveyed on a conveying path, by ejecting ink according to image data. It has a side paper feeding section 10 , an internal paper feeding section 20 , a printing section 30 , a paper discharge section 40 and a reversing section 50 .

The side paper feed unit 10 includes a paper feed tray 11 on which paper sheets P are stacked, a pickup paper feed section 12 that conveys only the topmost paper sheet P from the paper feed tray 11 onto the paper feed conveyance path FR, and the pickup. A registration section 14 corrects the skew of the sheet P conveyed by the sheet feeding section 12 and conveys it onto the circulation conveying path CR at a predetermined conveying timing.

The internal paper feed unit 20 includes paper feed trays 21a, 21b, 21c, and 21d on which paper sheets P are stacked, and paper feed trays 21a, 21b, 21c, and 21d from which only the paper sheets P at the uppermost position are placed on the paper feed transport path FR. and pick-up paper feeding units 22a, 22b, 22c, and 22d for conveying the paper to the storage area.

The sheet P is conveyed to the registration section 14 from the side sheet feeding section 10 and the internal sheet feeding section 20, and further, the sheet P is also conveyed from the reversing section 50, which will be described later. Therefore, before the registration unit 14 in the transport direction, there is a confluence point where the transport path for the fed paper P and the transport path for circulating and transporting the paper printed on one side are joined. do. Based on this confluence point, the path on the side of the paper feed mechanism is called the paper feed transport path FR, and the other transport path is called the circulation transport path CR. A printing unit 30 is provided on the transport direction side of the registration unit 14 .

The printing unit 30 includes an inkjet unit 31, which is an ink ejection means incorporating a plurality of print heads, and an annular transport belt 133 provided on the opposite surface of the inkjet unit 31 and sliding along the circulation transport path CR. The paper P fed by the registration unit 14 is placed inside the annular conveying belt 133 corresponding to the rear surface of the paper conveying road surface BP, and the paper P is attracted to the upper surface of the conveying belt 133 and conveyed. The paper P is printed with ink ejected from the inkjet unit 31 while being sucked onto the conveying belt 133 by the suction fan 131 and being conveyed at a predetermined conveying speed.

A charged charging roller (charging member) 32 is provided downstream of the inkjet unit 31 in the transport direction and above the transport belt 133 . The charging roller 32 electrostatically attracts mist generated when ink is ejected from the inkjet unit 31 onto the paper P transported on the transport belt 133 . Details will be described later.

The paper P printed by the printing unit 30 is transported on the circulation path CR inside the housing by transport rollers or the like arranged on the circulation path CR. On the circulation path CR, a switching mechanism 43 is provided for switching between guiding the paper P transported on the circulation path CR to the paper discharge section 40 and recirculating on the circulation path CR. .

A switching mechanism 43, which is one of the conveying means, switches to guide the sheet P to either the sheet discharging section 40 or the reversing section 50, which will be described later. The paper discharge unit 40 has a tray-shaped paper discharge table 41 protruding from the housing of the inkjet printing apparatus 1 and a pair of paper discharge rollers 42 for guiding the paper P to the paper paper table 41 . Then, the paper P guided to the paper discharge section 40 by the switching mechanism 43 is conveyed to the paper discharge table 41 by the paper discharge rollers 42 and stacked on the paper discharge table 41 with the printed surface facing down.

The reversing section 50, which is one of the conveying means, includes a reversing table 51 for reversing the paper P, and conveys the paper P from the circulation conveying path CR to the reversing table 51, or conveys the paper P from the reversing table 51 onto the circulation conveying path CR. and a reversing roller 52 that conveys the

The sheet P guided to the reversing section 50 by the switching mechanism 43 is conveyed from the circulation conveying path CR to the reversing table 51 by the reversing rollers 52, and after a predetermined time has passed, is conveyed from the reversing table 51 to the circulation conveying path CR. , the front and back are reversed with respect to the circulating transport path CR. Then, the sheet P whose front and back sides have been reversed is conveyed toward the printing section 30 on the circulating conveying path CR by a plurality of rollers such as the conveying rollers 53 provided on the circulating conveying path CR.

It also has a control unit 80 that controls the entire inkjet printer 1 . The control unit 80 is configured by hardware such as a processor such as a CPU or DSP (Digital Signal Processor), memory, and other electronic circuits, or software such as a program having such functions, or a combination thereof. Arithmetic module. The control unit 80 virtually constructs various functional modules by appropriately reading and executing programs, and the constructed functional modules perform processing related to image data, operation control of each unit, and various processing for user operations. I do. Specifically, the control unit 80 controls the side paper feeding unit 10, the internal paper feeding unit 20, the printing unit 30, the paper discharging unit 40, and the reversing unit 50 to perform printing based on the print job. Execute the process.

FIG. 2 is an enlarged side view of the printing unit 30 included in the inkjet printer 1 according to one embodiment of the invention.

As shown in FIG. 2, a charging roller 32 that is positively or negatively charged is provided downstream of the inkjet unit 31 in the transport direction of the paper P and above the transport belt 133 .

When the sheet P is conveyed at a predetermined conveying speed while being sucked onto the conveying belt 133, an air current R is generated along the conveying direction of the sheet P. FIG. At this time, minute droplets (mist) generated along with the ejection of ink (main droplets), which are not used for image formation, are flowed downstream by the airflow R. FIG.

The charging roller 32 rotates in the direction A around its rotation axis, and attracts the mist entrained in the airflow R to its surface by electrostatic action.

A shielding member 33 made of an elastic material is provided above the charging roller 32 . An upper portion of the shielding member 33 is fixed to the wall surface 36 . The charging roller 32 and the shielding member 33 are separated by a fixed member 34 at a predetermined distance. This predetermined interval is set to a short distance so that the shielding members 33 do not come into contact with each other even when the shielding members 33 are elastically deformed.

As a result, the airflow R is less likely to pass above the charging roller 32 and passes below the charging roller 32 .

A lifting mechanism 35 for lifting and lowering the fixing member 34 is fixed to the wall surface 36 . The elevating mechanism 35 elevates the charging roller 32 and the shielding member 33 with respect to the conveying belt 133 by elevating the fixing member 34 in the vertical direction. Specifically, the charging roller 32 is positioned at a mist adsorption position (indicated by a dashed line) having a predetermined gap above the paper P transported on the top surface of the transport belt 133 and the paper P transported on the top surface of the transport belt 133 . That is, the charging roller 32 is moved up and down between the cleaning position (indicated by the solid line) where the gap is zero.

Thus, when cleaning the charging roller 32, the lifting mechanism 35 lowers the charging roller 32 to the cleaning position, and when printing, raises the charging roller 32 to the mist collection position to collect the mist. . The mist collection position will be described later.

(Functional configuration of inkjet printer 1)
FIG. 3 is a diagram showing the functional configuration of the inkjet printer 1 that is one embodiment of the present invention.

As shown in FIG. 3 , the inkjet printer 1 has a control section 80 , and the control section 80 is electrically connected to the ROM 85 .

The ROM 85 stores an operation program executed by the control unit 80 and various tables such as a gap adjustment table.

FIG. 4 is a diagram showing an example of the gap adjustment table stored in the ROM 85. As shown in FIG.

The inkjet printer 1 uses a plurality of types of ink depending on the ink color. Different types of ink have different characteristics (viscosity, surface tension, etc.). The ink (main droplet) ejected from the inkjet unit 31 has a large tip portion, and a thin rod-shaped liquid column is formed from the tip portion to the tail end portion. The length of this thin liquid column is called the ink column length, and the longer the ink length, the more mist is likely to be generated. This ink column length is determined by the properties of the ink.

In the diagram shown in FIG. 4, the coverage factor calculated based on the maximum coverage factor and the gap corresponding to this coverage factor are stored for each ink color (for each ink column length). The maximum print rate is the highest print rate among the print rates of the pages included in the job. The gap is the distance between the charging roller 32 and the upper surface of the conveying belt 133 .

The higher the maximum print rate and the longer the ink column length, the greater the maximum amount of mist generated per unit time.

As a result, when the maximum amount of mist generated per unit time is large, mist can be collected efficiently, and when the maximum amount of mist generated per unit time is small, the risk of collision with paper can be reduced. .

Returning to FIG. 3, the control unit 80 has a determination means 81 and a control means 82 functionally.

The determining unit 81 receives a job from the outside and calculates the maximum print rate for the paper P from the image data included in the received job. Then, the gap between the charging roller 32 and the upper surface of the conveying belt 133 is determined based on the calculated maximum print rate, ink characteristics (ink column length), and the gap adjustment table stored in the ROM 85 .

The control means 82 controls the lifting mechanism 35 so that the gap determined by the determination means 81 is achieved.

In this way, when the maximum amount of mist generated per unit time is large, the mist can be collected efficiently by narrowing the gap, and when the maximum amount of mist generated per unit time is small, the gap can be widened. can reduce the risk of collision with the paper. Therefore, it is possible to reduce the risk of paper contact while achieving high mist collection efficiency.

Further, the control means 82 controls the motor 37 so as to rotate the charging roller 32 in the A direction.

FIG. 5 is an explanatory diagram illustrating the action of the inkjet printer 1 that is one embodiment of the present invention. 5(a) and 5(b) are explanatory diagrams showing generation and adsorption of mist during printing, and FIG. 5(c) is a diagram showing recovery of the adsorbed mist.

As shown in FIG. 5A, when printing is performed while the paper P is being transported by the transport belt 133, an air current R is generated along the transport direction of the paper P. As shown in FIG. At this time, the mist generated along with the ejection of the ink (main droplet) is flowed downstream by the airflow R.

Here, a power supply 38 is connected to the charging roller 32 and the inkjet unit 31 such that the charging roller 32 is positively charged and the inkjet unit 31 is negatively charged. Therefore, the mist is negatively charged.

The charging roller 32 has the lifting mechanism 35 controlled by the control means 82 so that the gap G determined by the determining means 81 is achieved. Here, the charging roller 32 is positively charged.

Therefore, the mist that is blown downstream by the airflow R is attracted to the surface of the charging roller 32 that is rotating, as shown in FIG. 5(b).

When cleaning the charging roller 32, the control unit 82 lowers the charging roller 32 to the cleaning position where the gap becomes zero so as to press the charging roller 32 against the cleaning paper P conveyed on the upper surface of the conveying belt 133. It controls the lifting mechanism 35 .

In this manner, the control means 82 controls the lifting mechanism 35 so that the charging roller 32 is at the mist attracting position during printing, and controls the lifting mechanism 35 so that the charging roller 32 is at the cleaning position during cleaning.

As a result, the cleaning of the charging roller 32 can be performed without removing the charging roller 32 and cleaning it.

Although cleaning paper is used for cleaning here, plain paper may be used. Further, the mist may be transferred to the printed paper P by controlling the lifting mechanism 35 so that the charging roller 32 is at the cleaning position during printing. In this case, although the print quality deteriorates to some extent, the cleaning operation is performed simultaneously with the printing, so that the cleaning can be efficiently performed.

FIG. 6 is a flow chart showing the processing contents of the inkjet printing apparatus 1, which is an embodiment of the present invention.

As shown in FIG. 6, it is determined whether or not a mode has been set by the user (step S101). User-configurable modes are "mist transfer" mode, or "high quality" mode. The "mist transfer" mode is a mode in which mist is transferred to the printed paper P by controlling the lifting mechanism 35 so that the charging roller 32 is positioned at the cleaning position during printing. is a mode for transferring mist onto the paper P for cleaning.

When the "mist transfer" mode is set by the user (step S101; mist transfer), it can be assumed that the user does not want high-quality printing, but wants to perform cleaning as efficiently as possible. .

Therefore, the control unit 80 determines whether or not the print amount exceeds the first print amount threshold based on the job (step S103). Here, the first print amount threshold is set in advance as a print amount corresponding to an amount of mist that is inconspicuous even when printed.

If the print amount exceeds the first print amount threshold (step S103; YES), it means that the mist adheres to the charging roller 32 to such an extent that it is noticeable when transferred to the paper P.

Therefore, the control means 82 executes a cleaning operation (step S105). Specifically, the control unit 82 causes the paper P to be fed from any of the paper feed trays 21a, 21b, 21c, and 21d, turns off the charging of the charging roller 32, and causes the lifting mechanism 35 to clean the charging roller 32. Lower to position.

As a result, it is possible to remove the mist adhering to a conspicuous degree using the paper P for cleaning.

Then, the control unit 82 turns on the charging of the charging roller 32 and causes the lifting mechanism 35 to lower the charging roller 32 to the cleaning position (step S107), and executes the printing process (step S109). As a result, the cleaning operation is performed simultaneously with the printing, so that the cleaning can be efficiently performed.

On the other hand, in step S101, when the "high image quality" mode is set by the user setting (step S101; high image quality), the user does not desire efficient cleaning, but wants to print with as high image quality as possible. I can guess.

Therefore, the control means 82 turns on the charging of the charging roller 32 (step S111), and adjusts the gap of the charging roller 32 (step S113). Specifically, the determination unit 81 determines the gap between the charging roller 32 and the upper surface of the conveying belt 133 based on the maximum printing rate, ink characteristics (ink column length), and the gap adjustment table stored in the ROM 85 . is determined, and the control means 82 controls the lifting mechanism 35 so that the gap determined by the determination means 81 is achieved.

The control unit 82 executes print processing (step S109). As a result, the charging roller 32 can attract generated mist to the surface while maintaining an appropriate gap with respect to the upper surface of the conveying belt 133 .

Next, the control unit 80 determines whether or not the print amount exceeds the second print amount threshold based on the job (step S117). Here, the second print amount threshold is set in advance as a print amount corresponding to the amount of mist that is attracted to the surface of the charging roller 32 and does not fall off.

If the print amount exceeds the second print amount threshold (step S117; YES), it means that the mist has accumulated on the surface of the charging roller 32 to such an extent that it will drop if it is attracted any more.

Therefore, the control means 82 executes a cleaning operation (step S119). Specifically, the control unit 82 causes the paper P to be fed from any of the paper feed trays 21a, 21b, 21c, and 21d, turns off the charging of the charging roller 32, and causes the lifting mechanism 35 to clean the charging roller 32. Lower to position.

As a result, the attached mist can be removed using the paper P for cleaning.

Then, the process is moved to step S111 again, and the processes of S111 to S119 are repeatedly executed.

As described above, according to the inkjet printing apparatus 1 according to the embodiment of the present invention, the charging roller 32 is charged when the ink is ejected from the inkjet unit 31 onto the paper P conveyed on the conveying belt 133. The mist is attracted to the surface by electrostatic action, and the lifting mechanism 35 lifts and lowers the charging roller 32 with respect to the conveying belt 133 .

As a result, the interval between the charging roller 32 and the conveying belt 133 can be adjusted according to the amount of mist generated, so that the risk of contact with the paper can be reduced while achieving high mist collection efficiency.

In one embodiment of the present invention, the charging roller 32 is provided. In other words, it is only necessary to have a shape that does not interfere with the transport of the paper P.

Also, in one embodiment of the present invention, the mist is negatively charged and the charging roller 32 is controlled to be positively charged, but the present invention is not limited to this. If the mist is positively charged, the charging roller 32 is controlled to be negatively charged. If the mist has neither positive nor negative charge, the charging roller 32 may be controlled to have either positive or negative charge.

Further, in one embodiment of the present invention, the ink jet printing apparatus 1 having the annular transport belt 133 that slides along the circulation transport path CR has been described as an example. Any belt can be applied without being limited to the conveyor belt.

(Appendix)
This application discloses the following inventions.

(Appendix 1)
A mist collecting device for collecting mist generated when ink is ejected from an inkjet head onto a printing medium conveyed on a conveying path,
a conveying means for conveying the print medium along the conveying path;
a charging member that is provided downstream of the inkjet head and above the conveying means and that is charged;
an elevating mechanism for elevating the charging member with respect to the conveying means;
A mist collection device comprising:

As a result, the interval between the charging member and the conveying means can be adjusted, so that the interval can be narrowed when the amount of mist is large, and the interval can be widened when the amount of mist is small. As a result, it is possible to reduce the risk of contact with the print medium while achieving high mist collection efficiency.

(Appendix 2)
a control means for controlling the lifting mechanism based on the state of mist generation,
The mist collection device according to (Appendix 1), further comprising:

As a result, the distance between the charging member and the conveying means can be adjusted according to the amount of mist generated, so the mist can be collected more efficiently.

(Appendix 3)
The conveying means conveys the print medium by adsorbing it on an upper surface of a conveying belt along the conveying path,
determining means for determining a gap between the charging member and the upper surface of the conveying belt based on the maximum print rate for each job and the characteristics of the ink;
The mist collection device according to (Appendix 2), wherein the control means controls the elevating mechanism so that the gap determined by the determining means is achieved.

As a result, for example, when the maximum amount of mist generated per unit time is large, the mist can be collected efficiently by narrowing the gap, and when the maximum amount of mist generated per unit time is small, the gap can be widened. Therefore, the risk of collision with the paper can be reduced. Therefore, it is possible to reduce the risk of contact with the print medium while achieving high mist collection efficiency.

(Appendix 4)
The mist collection device according to (Appendix 3), wherein the control means controls the elevation mechanism so as to press the charging member against the sheet conveyed on the upper surface of the conveying belt when cleaning the charging member. .

As a result, the charging member can be cleaned without removing the charging member and cleaning it.

(Appendix 5)
a shielding member provided above the charging member so as to shield an air current generated by conveying the printing medium from passing above the charging member;
The mist collection device according to any one of (Appendix 1) to (Appendix 4), further comprising:

As a result, the airflow generated by conveying the print medium does not easily pass above the charging member, but passes below the charging member, so that the mist can be properly attracted to the charging member.

1 Inkjet printing device 10 Side paper feed unit 11 Paper feed table 20 Internal paper feed unit 30 Printing unit 31 Inkjet unit 32 Charging roller (charging member)
33 Shielding member 34 Fixing member 35 Elevating mechanism 36 Wall surface 37 Motor 38 Power supply 40 Paper discharge unit 50 Reversing unit 80 Control unit 81 Determination means 82 Control means 131 Suction fan 133 Conveyor belt

Claims (4)

A mist collecting device for collecting mist generated when ink is ejected from an inkjet head onto a printing medium conveyed on a conveying path,
a conveying means for conveying the print medium by adsorbing it on the upper surface of the conveying belt along the conveying path;
a charging member that is provided downstream of the inkjet head and above the conveying means and that is charged;
an elevating mechanism for elevating the charging member with respect to the conveying means;
a control means for controlling the lifting mechanism based on the state of mist generation;
determining means for determining a gap between the charging member and the upper surface of the conveying belt based on the maximum print rate for each job and the characteristics of the ink;
The control means controls the lifting mechanism so that the gap determined by the determination means is achieved.
A mist collection device characterized by: 2. The mist collecting device according to claim 1 , wherein the controller controls the elevating mechanism so as to press the charging member against the sheet conveyed on the upper surface of the conveying belt when cleaning the charging member. a shielding member provided above the charging member so as to shield an air current generated by conveying the printing medium from passing above the charging member;
3. The mist collection device according to any one of claims 1 and 2 , further comprising: The charging member is provided downstream of the inkjet head and above the conveying means so as to be rotatable about a roller-shaped rotating shaft in a direction orthogonal to a conveying direction of conveying the print medium, and charges.
2. The mist collecting device according to claim 1, characterized in that:

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