JP2015139978A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect mist which is generated due to ink discharge and floating in a device, without deterioration of productivity.SOLUTION: An ink jet printer comprises: a mist amount calculation part 81a for calculating an amount of mist floating in a device caused by discharge of ink from an ink jet head 31; a determination part 81b for determining whether the mist amount calculated by the mist amount calculation part 81a exceeds a preset allowance mist amount, or not; a sheet interval calculation part 81c for calculating an interval of sheets P transferred by a transfer belt 133 so that the mist amount calculated by the mist amount calculation part 81a and the allowance mist amount can be matched with each other, when the determination part 81b determines the mist amount exceeds the allowance mist amount; and a drive control part 81e for controlling a resist part 14 and the transfer belt 133 or the like, so that the interval of the sheets P transferred by the transfer belt 133 can be an interval of the sheets which is calculated by the sheet interval calculation part 81c.

Description

  The present invention relates to an ink jet printing apparatus that collects mist generated by ink ejection and floating in the apparatus without reducing productivity.

  2. Description of the Related Art An ink jet printing apparatus prints on paper by ejecting ink droplets with an ink jet head, and is generally well known.

  Such an ink jet printing apparatus includes a transport belt for transporting paper below the ink jet head, and transports the paper at a predetermined paper interval while sucking the paper onto the transport belt by a suction fan installed in the transport belt. There is a full-line type that prints with ink ejected from an inkjet head.

  As described above, when the sheet is conveyed at a predetermined sheet interval while being sucked onto the conveying belt by the suction of the suction fan, an air flow passing through the sheet interval is generated by the suction by the suction fan. The mist generated by the ink ejection is collected along with the air flow.

  However, if the amount of mist generated by ink ejection increases or if suction by the suction fan is insufficient, the mist cannot be collected, and the mist that has not been collected may adhere to the apparatus and become dirty. .

  In Patent Document 1, a conveyance belt and a pressure reducing device are provided, and a fan that generates an air flow toward the inside of the conveyance belt is operated at a position where the mist suction area on the conveyance belt and the inkjet head face each other. Techniques related to an image recording apparatus that stops the traveling of the conveyor belt have been proposed.

JP 2010-23375 A

  However, in the image recording apparatus described in Patent Document 1, the conveyance is performed with a fan that generates an airflow toward the inside of the conveyance belt at a position where the mist suction area on the conveyance belt and the inkjet head face each other. Since the belt travel is stopped, the printing process cannot be executed while the transport belt travel is stopped. Therefore, there has been a problem that the productivity of printing is lowered.

  The present invention has been made in view of the above problems, and an object thereof is to provide an ink jet printing apparatus that collects mist generated by ink ejection and floating in the apparatus without reducing productivity.

  In order to achieve the above object, a first feature of an ink jet printing apparatus according to the present invention is an ink jet printing apparatus that discharges ink droplets to form an image on a sheet. A registration unit that supplies paper at predetermined time intervals, a plurality of suction holes are provided, a conveyance belt that conveys the sheet supplied by the registration unit, a lower part of the conveyance belt, and the conveyance belt A suction unit that sucks the conveyed paper through the plurality of suction holes, and a nozzle array arranged in parallel to a main scanning direction orthogonal to the paper transport direction; And an inkjet head that ejects ink from the nozzle row to the sheet that is sucked and conveyed on the conveyance belt, and the inkjet head. Mist amount calculation means for calculating the amount of mist floating in the apparatus by discharging ink from the printer, and whether or not the mist amount calculated by the mist amount calculation means exceeds a preset allowable mist amount When the determination means determines that the allowable mist amount is exceeded, the conveyance belt conveys the mist amount calculated by the mist amount calculation means so as to match the allowable mist amount. Paper interval calculating means for calculating the interval of the paper to be processed, and controlling the registration means and the conveyor belt so that the interval of the paper conveyed by the conveyor belt becomes the interval of the paper calculated by the paper interval calculator Drive control means.

  Further, a second feature of the ink jet printing apparatus according to the present invention is that the mist amount calculating means includes a distance between the ink jet head and the transport belt, a distance between sheets conveyed by the transport belt, a temperature of the ink, A mist amount generated by the print job is calculated based on one or more of the number of pixels of the image printed by the print job and the number of printed sheets, and the mist amount sucked by the suction unit from the calculated mist amount The amount of floating mist is calculated by subtracting.

  A third feature of the ink jet printing apparatus according to the present invention is that the image quality priority mode that prioritizes the image quality of the image printed by the ink ejection by the ink jet head or the production that prioritizes the productivity of printing by external input. Mode setting means for setting any one of the sex priority modes, and storage means for storing the information as productivity information in association with the size of the paper and the maximum paper interval allowed for ensuring the productivity. The paper interval calculating means calculates the mist amount calculated by the mist amount calculating means when the image quality priority mode is set by the mode setting means when the calculated paper interval is larger than the maximum paper interval. Calculates the interval of the paper transported by the transport belt so as to match the allowable mist amount, and sends it to the mode setting means. When the productivity priority mode is set, based on the productivity information, the maximum sheet interval corresponding to the size of the sheet conveyed by the conveying belt is set as the interval of the sheet conveyed by the conveying belt. It is in.

  A fourth feature of the ink jet printing apparatus according to the present invention is that a light emitting element that emits light into a mist floating space in which mist floats when ink is ejected from the ink jet head; A light receiving element on which the light propagated through the mist floating space is incident, and the mist amount calculating means is configured to determine the amount of mist floating in the mist floating space based on the amount of light incident on the light receiving element. It is to be calculated as the amount of mist floating inside.

  According to the first feature of the ink jet printing apparatus according to the present invention, the mist amount calculating means calculates the mist amount floating in the apparatus by ejecting ink from the ink jet head, and the determining means includes the mist amount. It is determined whether or not the mist amount calculated by the calculation means exceeds a preset allowable mist amount. When the paper interval calculation means determines that the allowable mist amount exceeds the allowable mist amount, the mist amount calculation means The interval between the sheets conveyed by the conveyance belt is calculated so that the mist amount calculated by the above coincides with the allowable mist amount, and the drive control unit calculates the interval between the sheets conveyed by the conveyance belt by the sheet interval calculation unit. The registration means and the conveying belt are controlled so that the interval between the printed sheets is the same. As a result, the travel of the conveyor belt is not stopped, so that a decrease in productivity of the printing process can be suppressed, and the sheet is set up to the sheet interval set so that the calculated mist amount becomes the allowable mist amount. Since the printing process is performed with a longer interval, it is possible to collect as much as possible the mist generated by the ink ejection and floating in the apparatus by increasing the air volume by the suction of the suction fan. Therefore, it is possible to collect mist generated by ink ejection without reducing productivity.

  According to the second feature of the ink jet printing apparatus according to the present invention, the mist amount calculating means prints according to the distance between the ink jet head and the transport belt, the distance of the paper transported by the transport belt, the temperature of the ink, and the print job. The mist amount generated by the print job is calculated based on one or more of the number of pixels of the image to be printed and the number of printed sheets, and the floating mist is obtained by subtracting the mist amount sucked by the suction means from the calculated mist amount. Since the amount is calculated, the amount of floating mist can be calculated more accurately.

  According to the third feature of the ink jet printing apparatus according to the present invention, when the paper interval calculation means sets the image quality priority mode by the mode setting means when the calculated paper interval is larger than the maximum paper interval. When the productivity priority mode is set by the mode setting means by calculating the interval of the paper conveyed by the conveyor belt so that the mist amount calculated by the mist amount calculating means matches the allowable mist amount, Based on the information, the maximum paper interval corresponding to the size of the paper conveyed by the conveyor belt is set as the interval of the paper conveyed by the conveyor belt, so whether the user wants to print with priority on the image quality of the printed image Alternatively, it is possible to determine the sheet interval according to the user's preference whether printing is desired without reducing productivity.

  According to the fourth feature of the ink jet printing apparatus according to the present invention, the mist amount calculating means sets the mist amount floating in the mist floating space as the mist amount floating in the device based on the amount of light incident on the light receiving element. Since it is calculated, the amount of floating mist can be calculated by simple calculation, so that the calculation load can be reduced.

It is a block diagram which shows the structure of the inkjet printing apparatus which is Example 1 of this invention. It is the figure which showed the function structure of the inkjet printing apparatus which is Example 1 of this invention. It is the figure which showed an example of the coefficient information memorize | stored in ROM with which the inkjet printing apparatus which is Example 1 of this invention is provided. It is the figure which demonstrated typically the airflow which generate | occur | produces by the suction of the suction fan with which the inkjet printing apparatus which is Example 1 of this invention is provided. It is the flowchart which showed the process sequence of the inkjet printing apparatus which is Example 1 of this invention. It is the flowchart which showed the process sequence of the inkjet printing apparatus which is Example 2 of this invention. (A) is a side view of the inkjet head 31 and a conveyance belt with which the inkjet printing apparatus which is Example 3 of this invention is provided, FIG.7 (b) is an enlarged view of a mist sensor.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1
<Overall configuration of inkjet printing apparatus>
The configuration of the inkjet printing apparatus 1 that is Embodiment 1 of the present invention will be described in detail.

  FIG. 1 is a configuration diagram illustrating a configuration of an inkjet printing apparatus 1 that is Embodiment 1 of the present invention.

  As shown in FIG. 1, the inkjet printing apparatus 1 includes a side paper feed unit 10, an internal paper feed unit 20, a printing unit 30, a paper discharge unit 40, and a reversing unit 50.

  The side paper feeding unit 10 includes a paper feeding table 11 on which the paper P is stacked, a pickup paper feeding unit 12 that conveys only the uppermost paper P from the paper feeding table 11 onto the paper feeding conveyance path FR, and the pickup. And a registration unit 14 that corrects the skew of the sheet P conveyed by the sheet feeding unit 12 and conveys the sheet P onto the circulation conveyance path CR at a predetermined conveyance timing. A registration sensor 141 is provided in front of the registration unit 14 in the conveyance direction, and detects the leading edge or the trailing edge of the sheet P to be conveyed.

  The internal paper feed unit 20 includes a paper feed tray 21a on which the paper P is stacked, a pickup paper feed unit 22a that transports only the uppermost paper P from the paper feed tray 21a onto the paper feed transport path FR, and a paper P Are stacked, a pickup sheet feeding unit 22b that conveys only the uppermost sheet P from the sheet feeding table 21b onto the sheet feeding conveyance path FR, and a sheet feeding table 21c on which the sheets P are stacked. The pickup sheet feeding unit 22c that conveys only the uppermost sheet P from the sheet feeding table 21c onto the sheet feeding conveyance path FR, the sheet feeding table 21d on which the sheets P are stacked, and the uppermost position from the sheet feeding table 21d. Pickup paper feed section 22d for transporting only paper P on the paper feed transport path FR.

  As described above, the paper P is transported to the registration unit 14 from the side paper feeding unit 10 and the internal paper feeding unit 20, and the paper P is also transported from the reversing unit 50 described later.

  For this reason, a junction point where the conveyance path of the fed paper P and the path through which the paper on which one side is printed is circulated is merged exists in front of the registration unit 14 in the conveyance direction. . Based on this merging point, the path on the paper feed mechanism side is referred to as a paper feed conveyance path FR, and the other path is referred to as a circulation conveyance path CR.

  The printing unit 30 includes a piezoelectric element therein, and is provided on an opposing surface of the inkjet head 31 and an inkjet head 31 that ejects ink from nozzles provided in the lower part when voltage is applied to the piezoelectric element. The sheet P fed by the registration unit 14 is transported by the suction fan 131 installed in the annular transport belt 133 corresponding to the back surface of the sheet transport path. The ink is sucked onto 133 and printed on the paper P by the ink ejected from the inkjet head 31 while being transported at a predetermined transport speed.

  The inkjet heads 31 are arranged in a plurality of rows for each ink color of black (K), cyan (C), magenta (M), and yellow (Y) in the main scanning direction, that is, the direction orthogonal to the conveyance direction of the paper P. ing. Although not shown, thermometers for measuring the temperatures of black (K), cyan (C), magenta (M), and yellow (Y) inks are provided.

  The paper P printed by the printing unit 30 is conveyed on the circulation conveyance path CR in the housing by a conveyance roller or the like disposed on the circulation conveyance path CR. On the circulation conveyance path CR, a switching mechanism 43 that switches between guiding the paper P conveyed on the circulation conveyance path CR to the paper discharge unit 40 or recirculating on the circulation conveyance path CR is provided. .

  The switching mechanism 43 switches the paper P in order to guide the paper P to one of a paper discharge unit 40 and a reversing unit 50 described later.

  The paper discharge unit 40 includes a tray-shaped paper discharge table 41 protruding from the casing of the inkjet printing apparatus 1 and a pair of paper discharge rollers 42 that guide the paper P to the paper discharge table 41. Then, the paper P guided to the paper discharge unit 40 by the switching mechanism 43 is transported to the paper discharge table 41 by the paper discharge roller 42 and stacked on the paper discharge table 41 with the printing surface down.

  The reversing unit 50 includes a reversing table 51 for reversing the paper P, and a reversing roller 52 that transports the paper P from the circulation conveyance path CR to the reversing table 51 or conveys the paper P from the reversing table 51 onto the circulation conveyance path CR. It has.

  The sheet P guided to the reversing unit 50 by the switching mechanism 43 is transported from the circulation transport path CR to the reversing table 51 by the reversing roller 52, and is transported from the reversing table 51 to the circulation transport path CR after a predetermined time. The front and back are reversed with respect to the circulation conveyance path CR. The sheet P with the front and back reversed is conveyed toward the printing unit 30 on the circulation conveyance path CR by a plurality of rollers such as a conveyance roller 53 provided on the circulation conveyance path CR.

  Moreover, it has the control part 80 which controls the whole inkjet printing apparatus 1. FIG. The control unit 80 controls the side paper feeding unit 10, the internal paper feeding unit 20, the printing unit 30, the paper discharge unit 40, and the reversing unit 50 to execute a printing process based on a print job. To do.

<Functional Configuration of Inkjet Printing Apparatus 1>
Next, a functional configuration of the inkjet printing apparatus 1 that is Embodiment 1 of the present invention will be described.

  FIG. 2 is a diagram illustrating a functional configuration of the inkjet printing apparatus 1 that is Embodiment 1 of the present invention.

  As shown in FIG. 2, the inkjet printing apparatus 1 includes a side paper feed unit 10, an internal paper feed unit 20, a printing unit 30, a paper discharge unit 40, a reversing unit 50, an operation panel unit 70, and a control. Unit 80 and a communication interface 90. Among these configurations, the side paper feeding unit 10, the internal paper feeding unit 20, the printing unit 30, the paper discharge unit 40, and the reversing unit 50 have been described above, and a description thereof will be omitted.

  The communication interface 90 is a communication interface that transmits and receives data to and from a computer device (not shown), and receives a print job by, for example, a wired / wireless LAN, a serial method, or a USB method.

  The operation panel unit 70 is used to input a display / input panel (not shown), a start key for starting reading and printing, a stop key for stopping reading and printing, and the number of prints. Various operation keys such as a numeric keypad (not shown) are provided, and an operation signal based on a user operation is supplied to the control unit 80.

  The operation panel unit 70 includes a pressure-sensitive or electrostatic transparent touch panel disposed on the front surface, and a liquid crystal display panel (none of which is shown) disposed on the back surface of the touch panel and displaying various display screens. have. The user can perform various button pressing operations such as mode selection displayed on the display screen by directly touching the surface of the touch panel with a finger or the like while viewing the display screen of the liquid crystal display panel.

  The control unit 80 is transmitted by the CPU 81, the ROM 82 storing the operation program of the CPU 81 and various tables, the image data read by the image reading unit (not shown), the computer device (not shown), and the like. The RAM 83 stores image data and a print job including various printing conditions from the operation panel unit 70 or a computer device (not shown).

  The ROM 82 associates the paper type such as plain paper or envelope paper with the interval between the inkjet head 31 and the platen belt 160, and the paper size and the interval of the paper conveyed on the conveyance belt 133 during normal printing. Are associated with each other and stored as print setting information. In the ROM 82, the paper size and the maximum paper interval allowed for ensuring productivity are associated with each other and stored as productivity information.

  Here, in order to ensure productivity during normal printing, the correspondence relationship between the paper size and the paper interval is set. However, the correspondence relationship according to the printing speed (120 ppm, 150 ppm, etc.) should be prepared. Also good.

  Further, the ROM 82 stores a coefficient A of the interval between the inkjet head 31 and the platen belt 160 and a coefficient C of the ink temperature as coefficient information.

  FIG. 3 is a diagram illustrating an example of coefficient information stored in the ROM 82 provided in the inkjet printing apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 3, a coefficient name 101, a printing condition 102, and a coefficient value 103 are stored in association with each other.

  For example, the coefficient value 103 for the coefficient A of the interval 102 between the ink jet head and the platen belt is “0.6” (during high-definition printing), “1.0” (during plain paper printing), “1.4” ( (When envelope printing) is associated and stored.

  The CPU 81 executes the operation program stored in the ROM 82, so that the entire apparatus, that is, the side paper feed unit 10, the internal paper feed unit 20, the printing unit 30, the paper discharge unit 40, and the reversing unit 50 The operation of the operation panel unit 70 is controlled.

  The CPU 81 also includes a mist amount calculation unit 81a, a determination unit 81b, a paper interval calculation unit 81c, a mode setting unit 81d, and a drive control unit 81e.

  The mist amount calculation unit 81a calculates the amount of mist floating in the apparatus when ink is ejected from the inkjet head 31. Specifically, the mist amount calculation unit 81a has a gap between the inkjet head 31 and the conveyance belt 133 that affects the amount of floating mist, an interval between the sheets P conveyed by the conveyance belt 133, an ink temperature, and image data. The amount of floating mist is calculated based on the number of pixels and the number of printed sheets. The longer the distance between the inkjet head 31 and the transport belt 133, the more difficult it is to be sucked by the suction fan 131, so the amount of mist increases. As the interval of the paper P conveyed by the conveying belt 133 is longer, the mist discharged from the inkjet head 31 is more easily sucked by the suction fan 131, and the amount of floating mist is reduced. If the temperature of the ink is low, the voltage applied to the piezoelectric element when ink is ejected from the inkjet head 31 is increased in order to perform printing appropriately, so that the amount of mist increases accordingly. As the number of pixels of the image data increases, the number of mists increases because the number of ejection points increases. As the number of printed sheets increases, the amount of mist accumulated in the apparatus increases.

  The determination unit 81b determines whether or not the mist amount calculated by the mist amount calculation unit 81a exceeds a preset allowable mist amount.

  When it is determined that the mist amount calculated by the mist amount calculation unit 81a by the determination unit 81b exceeds a preset allowable mist amount, the sheet interval calculation unit 81c calculates the mist amount calculated by the mist amount calculation unit 81a. The set sheet interval set as the interval of the sheet P conveyed by the conveying belt 133 so as to match the allowable mist amount is calculated.

  The mode setting unit 81d is an image quality priority mode that prioritizes the image quality of an image printed by ink ejection by the inkjet head 31 or a productivity priority mode that prioritizes printing productivity, based on a user input from the operation panel unit 70. Set either one.

  The drive control unit 81e has the side paper feeding unit 10, the internal paper feeding unit 20, and the printing so that the interval of the paper P conveyed by the conveyance belt 133 becomes the set paper interval calculated by the paper interval calculation unit 81c. The unit 30, the paper discharge unit 40, and the reversing unit 50 are controlled to print an image on the paper P.

  FIG. 4 is a diagram schematically illustrating an air flow generated by suction of the suction fan 131 provided in the inkjet printing apparatus 1 that is Embodiment 1 of the present invention.

  As shown in FIG. 4, the platen belt 160 that conveys the paper P, the platen 200 and the platen template 300 that support the platen belt 160, and the suction that generates a negative pressure on the lower surface of the platen template 300 are included in the circulation conveyance path CR. A suction fan 131 as means is provided.

  The platen belt 160 is an endless belt member that has a number of belt holes 165 for attracting the paper P at regular intervals and conveys the paper P while adsorbing it. The platen belt 160 is supported by the platen 200 and the plate template 300, is wound around a pair of rollers (not shown) arranged orthogonal to the conveyance direction, is circulated in the conveyance direction, and slides on the upper surface of the platen 200. Is done.

  The platen 200 is a plate-like plate member that supports the platen belt 160 in a slidable manner and has a large number of suction holes 211 that pass through the belt holes 165. The platen 200 is fixed to a plastic template 300 that is a plate-like plate member having a large number of suction holes 301.

  Below the plastic template 300, there is provided a suction fan 131 which is a suction means for generating a negative pressure for sucking the paper P on the platen belt 160 through the belt hole 165, the suction hole 211, and the suction hole 301. Yes.

  As described above, the platen belt 160 is provided with a plurality of belt holes 165, and in the region where there is no paper P on the platen belt 160, the belt holes 165, the suction holes 211, and the suction holes from the direction of the inkjet head 31. An air flow F <b> 1 that passes through 301 and is guided toward the suction fan 131 is generated.

  At this time, the ink droplets ejected from the nozzle row 121 of the inkjet head 31 fly in a tailed manner, and a time difference or speed difference is generated between the leading portion and the trailing portion of the flying droplet. Along with the preceding main droplet 201, a mist 203 which is an unnecessary minute droplet is generated.

  At this time, regardless of the number of ink droplets, the droplets according to the main droplets advance and merge, and most of the mist is generated from the end of the last droplet. For this reason, the number of ink droplets does not cause floating mist. The mist 203 is sucked by the suction fan 131 along with the airflow F1 flowing in the vicinity. If the amount of the mist 203 is large, it cannot be completely sucked by the suction fan 131 and floats in the apparatus. Mist floating in the apparatus in this way is referred to as floating mist 204.

  For this reason, the longer the distance L between the preceding sheet (nth sheet P) and the subsequent sheet (n + 1th sheet P), the greater the air volume of the air flow F1, so the floating mist 204 is reduced. It becomes easy to collect.

<Operation of inkjet printing apparatus>
FIG. 5 is a flowchart showing a processing procedure of the inkjet printing apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 5, when the control unit 80 of the inkjet printing apparatus 1 receives a print job via the communication interface 90 (step S101), first, after substituting “1” as the initial value for the value of the variable n. (Step S103), printing conditions are extracted (Step S105). For example, the mist amount calculation unit 81a of the control unit 80 extracts image data, paper type, paper size, and number of prints for each page from the print job. The mist amount calculation unit 81a calculates the number of pixels ejected from the inkjet head 31 by generating RGB data that has been bitmap-developed from the image data and performing color conversion from the RGB data to CMYK data. Further, the mist amount calculation unit 81a extracts the interval between the ink jet head 31 corresponding to the sheet type and the platen belt 160 based on the print setting information stored in the ROM 82, and extracts the sheet interval corresponding to the sheet size. . Further, the mist amount calculation unit 81a acquires the temperatures of the black (K), cyan (C), magenta (M), and yellow (Y) inks measured by the thermometer, and averages the temperatures of the inks of the respective colors. Is calculated as the ink temperature.

  Thereby, the mist amount calculation unit 81a can acquire the number of pixels for each page, the interval between the inkjet head 31 and the platen belt 160, the sheet interval, the ink temperature, and the number of printed sheets as the printing conditions.

  Next, the mist amount calculation unit 81a determines a coefficient for each printing condition in order to calculate the mist amount (step S107). Specifically, the mist amount calculation unit 81a includes, based on the coefficient information stored in the ROM 82, the coefficient A of the interval between the inkjet head 31 and the platen belt 160 and the coefficient C of the ink temperature among the printing conditions. decide. For example, when the paper type extracted from the print job is “envelope”, the mist amount calculation unit 81a determines the coefficient A of the interval between the inkjet head 31 and the platen belt 160 as “1.4”.

  Next, the mist amount calculation unit 81a calculates the floating mist amount when printing the nth page (step S109). Specifically, the mist amount calculation unit 81a is a suction mist amount that is a mist amount sucked by the suction fan 131 from a generated mist amount that is generated when ink droplets are ejected from the inkjet head 31. Is subtracted to calculate the amount of floating mist on the nth page.

  The generated mist amount N1 (n) on the n-th page includes a coefficient A of the interval between the inkjet head 31 and the platen belt 160, a coefficient C of the ink temperature, and the number of pixels D (n) on the n-th page. It is calculated by substituting into the following (Formula 1).

Generated mist amount N1 (n) = Generated mist reference amount [piece / pixel] × A × C × D (n) [pixel] (Equation 1)
Here, the generated mist reference amount is, for example, discharged to one pixel at a reference ink temperature such as 25 (° C.) or the interval between the inkjet head 31 and the platen belt 160 when printing plain paper. It is a value measured in advance as the amount of mist generated at the time.

  The suction mist amount N2 (n) for the nth page includes a coefficient A of the interval between the inkjet head 31 and the platen belt 160, a coefficient C of the ink temperature, and the number of pixels D (n) of the nth page. The sheet interval B [ms] is calculated by substituting into the following (Formula 2). Here, as the paper interval B [ms], the leading edge of the (n + 1) th sheet P has reached a certain point on the conveyor belt 133 from the time when the rear end of the nth sheet P has passed. Expressed as time to time.

Suction mist amount N2 (n) = Suction mist reference amount [piece / ms · pixel] × A × C × D (n) [pixel] × B [ms] (Equation 2)
Here, the reference amount of suction mist is, for example, a reference ink temperature such as 25 (° C.), and the interval between the inkjet head 31 and the platen belt 160 when printing plain paper, and one pixel per unit time (pixel). This is a value measured in advance as the amount of mist sucked by the suction fan 131 when discharged into the nozzle.

  Then, the mist amount calculation unit 81a calculates the floating mist amount Nf (n) when the nth page is printed by subtracting the suction mist amount N2 (n) from the generated mist amount N1 (n). To do.

  Next, the mist amount calculation unit 81a calculates the accumulated value of the floating mist amount Nf (n) from the first page to the nth page as the accumulated mist amount Na. (Step S111). Accordingly, it is possible to calculate the amount of mist floating in the apparatus when printing from the first page to the nth page.

  Then, the control unit 80 determines whether or not the floating mist amount has been calculated for all pages of the print job (step S113).

  When it is determined in step S113 that the floating mist amount is not calculated for all pages (step S113; NO), the control unit 80 adds the value of the variable n by “1” (step S115), When it is determined that the floating mist amount has been calculated for (Step S113; YES), the control unit 80 shifts the processing to Step S117. Thereby, at the end of the print processing of the print job, the mist amount floating in the apparatus can be calculated as the accumulated mist amount Na.

  The determination unit 81b determines whether or not the accumulated mist amount Na exceeds the allowable mist amount Nt (step S117). Here, the permissible mist amount [pieces] is a mist amount that can be allowed to float in the apparatus. For example, a correlation between the mist amount and image quality, apparatus contamination degree, and the like is experimentally obtained in advance. With that, it is set. An integer greater than or equal to “0” needs to be set in advance.

  If it is determined in step S117 that the accumulated mist amount Na is less than or equal to the allowable mist amount Nt (step S117; NO), the control unit 80 performs printing because the mist amount floating in the apparatus is within the allowable range. Processing is executed (step S133).

  On the other hand, if it is determined in step S117 that the accumulated mist amount Na has exceeded the allowable mist amount Nt (step S117; YES), the paper interval calculation unit 81c of the CPU 81 matches the accumulated mist amount Na with the allowable mist amount Nt. As described above, the set sheet interval of the sheet conveyed by the conveying belt 133 is calculated (step S119). Specifically, the sheet interval calculation unit 81c calculates the set floating mist amount Nfs (n) of the nth page using the following (Formula 3), and the first of the set floating mist amounts Nfs (n) is calculated. A set sheet interval Bs [ms] is calculated such that the integrated value from the page to the nth page becomes the allowable mist amount Nt.

Set floating mist amount Nfs (n) = generated mist reference amount [piece / pixel] × A × C × D (n) [pixel] −suction mist reference amount [piece / ms · pixel] × A × C × D (n ) [Pixel] × Bs [ms] (Formula 3)
Next, the paper interval calculation unit 81c calculates the maximum paper interval (step S121). Specifically, the sheet interval calculation unit 81c extracts the maximum sheet interval corresponding to the sheet size extracted from the print job in step S105 based on the productivity information stored in the ROM 82.

  Then, the sheet interval calculation unit 81c determines whether or not the set sheet interval Bs exceeds the maximum sheet interval Bm (step S123).

  When it is determined in step S123 that the set sheet interval Bs is equal to or less than the maximum sheet interval Bm (step S123; NO), the control unit 80 executes a printing process using the set sheet interval Bs (step S133). Specifically, the control unit 80 sets the side paper feeding unit 10, the internal paper feeding unit 20, and the like so that the interval of the paper P conveyed by the conveyance belt 133 becomes the set paper interval Bs calculated in step S 119. The printing unit 30, the paper discharge unit 40, and the reversing unit 50 are controlled to print an image on the paper P.

  On the other hand, when it is determined in step S123 that the set sheet interval Bs exceeds the maximum sheet interval Bm (step S123; YES), the sheet interval calculation unit 81c of the control unit 80 has the mode set by the mode setting unit 81d. It is determined whether the image quality priority mode or the productivity priority mode is set (step S127).

  If it is determined in step S127 that the image quality priority mode is set (step S127; image quality priority), the user should have a clear printed image even if the productivity is somewhat lower than that during normal printing. Since it can be estimated that the value is set, the value of the set sheet interval Bs exceeds the maximum sheet interval Bm, but the control unit 80 executes the printing process using the set sheet interval Bs calculated in step S119 ( Step S133).

  On the other hand, if it is determined in step S127 that the productivity priority mode is set (step S127; productivity priority), the user can improve the productivity even if the sharpness of the printed image is somewhat lower than during normal printing. Since it can be inferred that it is better to print with security, the paper interval calculation unit 81c substitutes the maximum paper interval Bm for the set paper interval Bs (step S129), and the control unit 80 assigns the newly assigned new value. A printing process is executed using the set sheet interval Bs (step S133).

  As described above, according to the inkjet printing apparatus 1 that is Embodiment 1 of the present invention, when ink is ejected from the inkjet head 31, a mist amount calculation unit 81a that calculates the amount of mist floating in the apparatus, When the mist amount calculated by the mist amount calculation unit 81a exceeds the preset allowable mist amount, the determination unit 81b determines that the mist amount exceeds the allowable mist amount. A sheet interval calculation unit 81c that calculates a set sheet interval of the sheet P conveyed by the conveyance belt 133 so that the mist amount calculated by the calculation unit 81a matches the allowable mist amount, and the sheet P conveyed by the conveyance belt 133 The registration unit 14 and the transport belt 133 are controlled so that the interval of the sheet is equal to the set sheet interval calculated by the sheet interval calculation unit 81c. Drive controller for and a 81e. For this reason, since the travel of the conveyor belt 133 is not stopped, a decrease in productivity of the printing process can be suppressed, and the sheet interval is increased to the set sheet interval such that the calculated mist amount becomes the allowable mist amount. Since the printing process is performed, the mist generated by the ink ejection and floating in the apparatus can be collected as much as possible by increasing the air volume by the suction of the suction fan 131.

  In Example 1 of the present invention, the mist amount calculation unit 81a calculates the generated mist amount N1 (n) using (Equation 1) and calculates the suction mist amount N2 (n) using (Equation 2). The floating mist amount Nf (n) when the nth page is printed is calculated by subtracting the suction mist amount N2 (n) from the generated mist amount N1 (n). The calculation method of N1 (n) and the suction mist amount N2 (n) is not limited to this, the interval between the inkjet head 31 and the conveyance belt 133, the interval between the sheets P conveyed by the conveyance belt 133, the ink temperature, and image data. The floating mist amount may be calculated based on one or more of the number of pixels and the number of printed sheets.

(Example 2)
In the inkjet printing apparatus 1 that is Embodiment 1 of the present invention, it is determined whether or not the accumulated mist amount exceeds the allowable mist amount for each print job, and the set sheet interval is determined. However, the present invention is not limited to this.

  In the inkjet printing apparatus 1 according to the second embodiment of the present invention, it is determined whether or not the floating mist amount calculated for each page of the print job exceeds the allowable mist amount, and the set sheet interval is determined for each page of the print job. You may do it. The hardware configuration and functional configuration of the inkjet printing apparatus 1 that is Embodiment 2 of the present invention are the same as the configuration of the inkjet printing apparatus 1 that is Embodiment 1 of the present invention shown in FIGS. 1 and 2. The description is omitted.

<Operation of inkjet printing apparatus>
FIG. 6 is a flowchart showing a processing procedure of the inkjet printing apparatus 1 according to the second embodiment of the present invention. In the flowchart shown in FIG. 6, the processes given the same step numbers as those in the flowchart shown in FIG.

  As shown in FIG. 6, in step S109, when the mist amount calculation unit 81a calculates the floating mist amount Nf (n) when printing the nth page, the determination unit 81b determines the floating mist amount Nf (n). It is determined whether or not the allowable mist amount Nt has been exceeded (step S201).

  When it is determined in step S117 that the floating mist amount Nf (n) is equal to or less than the allowable mist amount Nt (step S201; NO), the control unit is configured so that the mist amount floating in the apparatus is within the allowable range. 80 executes the printing process for the nth page (step S209).

  On the other hand, when it is determined in step S201 that the floating mist amount Nf (n) exceeds the allowable mist amount Nt (step S201; YES), the sheet interval calculation unit 81c of the CPU 81 allows the floating mist amount Nf (n) to be allowed. A set sheet interval set as an interval between sheets conveyed by the conveyance belt 133 is calculated so as to coincide with the mist amount Nt (step S203). Specifically, the sheet interval calculation unit 81c calculates the set floating mist amount Nfs (n) of the nth page using the above (Formula 3), and the set floating mist amount Nfs (n) A set sheet interval Bs [ms] is calculated such that the mist amount Nt is obtained.

  When it is determined in step S123 that the set sheet interval Bs is equal to or less than the maximum sheet interval Bm (step S123; NO), the control unit 80 uses the set sheet interval Bs to print the nth page. Is executed (step S209). Specifically, the control unit 80 sets the side paper feeding unit 10, the internal paper feeding unit 20, and the like so that the interval of the paper P conveyed by the conveyance belt 133 becomes the set paper interval Bm calculated in step S 203. The printing unit 30, the paper discharge unit 40, and the reversing unit 50 are controlled to print an image on the paper P.

  If it is determined in step S123 that the set sheet interval Bs exceeds the maximum sheet interval Bm (step S123; YES), if it is determined in step S127 that the productivity priority mode is set (step S127). Productivity priority), the paper interval calculation unit 81c substitutes the maximum paper interval Bm into the set paper interval Bs (step S129), and the control unit 80 uses the new set paper interval Bs thus substituted, The printing process for the first sheet is executed (step S209).

  Next, the control unit 80 determines whether or not the printing process has been completed for all pages (step S211), and when it is determined that the printing process has not been completed for all pages (step S211; NO). Then, the value of the variable n is incremented by “1” (step S115), and if it is determined that the printing process has been completed for all pages (step S211; YES), the process ends.

  As described above, according to the inkjet printing apparatus 1 that is Embodiment 2 of the present invention, it is determined whether or not the floating mist amount Nf (n) calculated for each page of the print job exceeds the allowable mist amount Nt. Therefore, it is possible to set an appropriate paper interval for each page.

  In the second embodiment of the present invention, it is determined whether or not the floating mist amount floating in the print processing of the nth page of the print job exceeds the allowable mist amount, and the set sheet interval of the nth page is determined. The printing process for the nth page has been executed, but after the set sheet intervals for the first to nth pages are determined in advance before starting the printing process, the printing process for the first to nth pages is executed. You may make it do.

  In the second embodiment of the present invention, it is determined whether or not the floating mist amount floating in the printing process of the nth page of the print job exceeds the allowable mist amount, and the set sheet interval of the nth page is determined. However, the present invention is not limited to this, and the determination may be made based on the accumulated mist amount Na.

  Specifically, the accumulated mist amount Na up to the nth page is calculated based on the floating mist amount floating in the printing process of the nth page of the print job, and whether the accumulated mist amount Na exceeds the allowable mist amount. It is possible to determine whether or not, determine the set sheet interval of the nth page based on the determination result, and execute the printing process of the nth page.

(Example 3)
In the inkjet printing apparatus 1 that is Embodiment 2 of the present invention, the mist amount calculation unit 81a subtracts the suction mist amount N2 from the generated mist amount N1, thereby causing the floating mist amount when the nth page is printed. Nf (n) is calculated, but the present invention is not limited to this.

  The inkjet printing apparatus 1 that is Embodiment 3 of the present invention includes a mist sensor that measures mist, and the mist amount calculation unit 81a prints the nth page based on the mist amount measured by the mist sensor. The floating mist amount Nf (n) at the time may be calculated.

  FIG. 7A is a side view of the inkjet head 31 and the conveyance belt 133 provided in the inkjet printing apparatus 1 that is Embodiment 3 of the present invention, and FIG. 7B is an enlarged view of the mist sensor.

  As shown in FIG. 7A, a mist sensor 32 is provided in the vicinity of the inkjet head 31 corresponding to each inkjet head 31, and the mist sensor 32 measures the amount of mist floating in the apparatus. .

  As shown in FIG. 7B, the mist sensor 32 emits light to a mist floating space 205 in which mist floats when ink is ejected from the inkjet head 31, and the light emitting element 321 emits the light. And a light receiving element 322 into which the light propagated through the mist floating space 205 and refracted by the floating mist is incident.

  Therefore, in the inkjet printing apparatus 1 according to the third embodiment of the present invention, as preparation, for the ink ejected from the inkjet head 31, for example, the ejection state such as the number of drops and the ink temperature is changed, and experimentally, The timing at which the amount of mist becomes the largest (elapsed time since ink was ejected from the inkjet head 31) is calculated.

  Then, the inkjet printing apparatus 1 causes each mist sensor 32 to actually detect the mist amount at the timing when the calculated mist amount becomes the largest.

  Here, since most of the mist generated by being ejected from the inkjet head 31 falls in the vicinity of the generated mist, if the measured value of the mist amount around the inkjet head 31 is substantially equal to the floating mist amount Nf (n). Can be estimated.

  Therefore, the mist amount calculation unit 81a included in the inkjet printing apparatus 1 according to the third embodiment of the present invention is based on the amount of light incident on the light receiving element 322 for each mist sensor 32 at the timing when the calculated mist amount is the largest. The amount of mist floating in the mist floating space 205 is calculated, and the calculated amount of mist for each mist sensor 32 is totaled to calculate the amount of floating mist Nf (n) that is the amount of mist floating in the apparatus.

  Thereby, since the mist amount calculation part 81a can calculate the floating mist amount Nf (n) by simple calculation, the calculation load of the CPU 81 can be reduced.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printing apparatus 10 ... Side paper feed part 12 ... Pickup paper feed part 14 ... Registration part (registration means)
DESCRIPTION OF SYMBOLS 20 ... Internal paper feed part 22a-22d ... Pickup paper feed part 30 ... Printing part 31 ... Inkjet head 32 ... Mist sensor 40 ... Paper discharge part 50 ... Reversing part 70 ... Operation panel part 80 ... Control part 81 ... CPU
81a ... Mist amount calculation unit 81b ... Determination unit 81c ... Paper interval calculation unit 81d ... Mode setting unit 81e ... Drive control unit 82 ... ROM
83 ... RAM
90 ... Communication interface 131 ... Suction fan (suction means)
133 ... Conveying belt 321 ... Light emitting element 322 ... Light receiving element

Claims (4)

An inkjet printing apparatus that forms an image on a sheet by ejecting ink droplets,
Registration means for supplying paper at predetermined time intervals on the transport path based on a print job;
A plurality of suction holes, a conveyance belt for conveying the paper supplied by the registration means;
A suction means provided below the transport belt and sucking the paper transported by the transport belt through the plurality of suction holes;
Nozzle rows are arranged so as to be parallel to the main scanning direction orthogonal to the paper transport direction, and based on the print job, the paper that is sucked and transported on the transport belt, An inkjet head that ejects ink from the nozzle row;
Mist amount calculating means for calculating the amount of mist floating in the apparatus by ejecting ink from the inkjet head;
Determining means for determining whether or not the mist amount calculated by the mist amount calculating means exceeds a preset allowable mist amount;
When it is determined by the determination means that the allowable mist amount has been exceeded, the interval between the sheets conveyed by the conveyance belt is calculated so that the mist amount calculated by the mist amount calculation means matches the allowable mist amount. Paper interval calculation means;
Drive control means for controlling the registration means and the conveyance belt so that the interval between sheets conveyed by the conveyance belt is equal to the sheet interval calculated by the sheet interval calculation means;
An ink jet printing apparatus comprising: The mist amount calculating means includes
Based on one or more of the interval between the inkjet head and the conveyance belt, the interval between sheets conveyed by the conveyance belt, the temperature of the ink, the number of pixels of an image printed by the print job, and the number of printed sheets, The mist amount generated by the print job is calculated, and the floating mist amount is calculated by subtracting the mist amount sucked by the suction unit from the calculated mist amount. Inkjet printing device. Mode setting means for setting one of an image quality priority mode that prioritizes the image quality of an image printed by ejecting ink from the inkjet head by an external input, and a productivity priority mode that prioritizes printing productivity;
Storage means for storing the information as productivity information in association with the size of the paper and the maximum paper interval allowed for guaranteeing productivity;
The paper interval calculation means includes:
When the calculated paper interval is larger than the maximum paper interval,
When the image quality priority mode is set by the mode setting unit, the interval between sheets conveyed by the conveyance belt is calculated so that the mist amount calculated by the mist amount calculating unit matches the allowable mist amount, When the productivity setting mode is set by the mode setting means, the maximum sheet interval corresponding to the size of the sheet conveyed by the conveyance belt is set based on the productivity information. The inkjet printing apparatus according to claim 1, wherein the interval is an interval. A light emitting element that emits light into a mist floating space in which mist floats by discharging ink from the inkjet head;
A light receiving element on which the light emitted from the light emitting element and propagated through the mist floating space is incident; and
The mist amount calculating means includes
The inkjet printing apparatus according to claim 1, wherein the amount of mist floating in the mist floating space is calculated as the amount of mist floating in the apparatus based on the amount of light incident on the light receiving element.

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