JP2013111760A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer which can obtain correct color measurement data by appropriately drying an image printed on a sheet by controlling in detail drying conditions of the image before color measurement.SOLUTION: Drying conditions of regions A, B and C by blowing air from a drying duct 13 are changed in response to the difficulty level of drying of the regions A, B and C on the sheet 1 on which color patches P for color measurement are printed.

Description

  The present invention relates to a printing apparatus having a colorimetric function for measuring an image printed on a sheet.

  Some inkjet printing apparatuses have a color measurement function for a printed image. According to such a printing apparatus, for the purpose of color calibration (color matching) or the like, the color image after printing is measured, and the color measurement data is reflected on the prints of the next and subsequent images. Color reproduction images can be printed. As a test pattern for obtaining color data, a pattern in which color patches of each ink color are arranged in a grid pattern is generally used. In color measurement work, generally, after the color patches printed on the sheet are dried, the color measurement sensor measures the color patches one by one while moving in the width direction of the sheet, and then after the color measurement. The sheet is discharged. By the way, in order to obtain the desired color measurement data, it is necessary to dry the color patch sufficiently, so that it takes time from the completion of printing the color patch to the start of color measurement.

  Japanese Patent Application Laid-Open No. 2004-228561 has a configuration in which a drying unit for forcibly drying a color patch is provided between the printing unit and the color measurement unit to shorten the time from the completion of color patch printing to the start of color measurement. Have been described. Further, in Patent Document 2, in order to shorten the drying time while preventing the heat of drying from the drying unit from affecting the printing unit and the color measuring unit, the printing unit, the color measuring unit, and the drying unit are provided with A configuration arranged in order is described.

JP 2007-230171 A JP 2008-254221 A

  In general, a printer having a color measurement unit is required to have more accurate color stability of a print image than a printer not having the color measurement unit. In Patent Document 1, a drying unit is installed, and in Patent Document 2, the layout of the colorimetric unit and the drying unit reduces the time from the completion of color patch printing to the start of colorimetry, and avoids the effects of drying heat. How to do is described. However, there is no particular description about means for controlling the drying conditions of the sheet by the drying unit.

  For example, in a large-format printer that handles 100 or more types of sheets, in order to reduce the time from the completion of color patch printing to the start of color measurement while ensuring the color stability of printed images on various sheets, the types of sheets It is necessary to change the drying conditions according to the above. Specifically, taking into account the difference in the degree of drying for each different sheet, the difference in the posture of the sheet after printing, the print duty of the color patch, the number of print passes of the color patch, or the usage environment of the printer, the sheet by the drying unit It is necessary to finely control the drying conditions.

  The present invention provides a printing apparatus capable of obtaining accurate colorimetric data by precisely controlling the drying conditions of an image printed on a sheet before colorimetric measurement, thereby accurately drying the image. It is to provide.

  The printing apparatus according to the present invention includes a printing unit that prints an image by applying ink to a sheet, a color measurement unit that measures the image printed by the printing unit, and the color measurement unit measures the image. Before drying, the drying unit that dries the region of the sheet on which the image is printed, and the drying condition of the region by the drying unit is changed according to the degree of difficulty in drying the region on which the image is printed. And a control unit.

  According to the present invention, by changing the drying conditions by the drying unit in accordance with the degree of difficulty in drying the region of the sheet on which the image is printed, the image can be accurately adjusted so that the image is not excessively dried and insufficiently dried. It is possible to improve the colorimetric accuracy of the image. Further, by shortening the drying time, it is possible to improve the throughput of the colorimetric work of the image. Further, by preventing insufficient drying of the sheet, it is possible to prevent scratches that are likely to occur when the sheet is conveyed.

1 is a schematic configuration diagram of a printing apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of the color measuring device in FIG. 1. (A), (b), and (c) are explanatory views of a series of operations of printing, colorimetry, and paper discharge by the printing apparatus of FIG. 2 is a flowchart for explaining a series of operations of printing, colorimetry, and paper discharge by the printing apparatus of FIG. It is explanatory drawing of the relationship between the color difference of an ink, and drying time. (A), (b) is explanatory drawing of the drying process in the printing apparatus of FIG. FIG. 2 is a block configuration diagram of a control system of the printing apparatus of FIG. 1.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
First, a schematic configuration of a printing apparatus 1 to which the present invention can be applied will be described with reference to FIG.

  A roll-shaped sheet 1 is stacked on the printing apparatus 100 in FIG. 1, and the type (sheet type) of the sheet 1 is input from the operation panel 25. Thereafter, the sheet 1 is conveyed in the direction of arrow A by the conveyance roller pair 2, and a color pattern for color measurement is printed by the printing unit 3, and then the color measurement device (color measurement unit) 200 provided in the printing apparatus 100. Be transported. The sheet 1 on which the color pattern is printed is colorimetrically measured by the colorimetric device 200, cut by the cutter 4, and then discharged to the outside of the printing device 100.

  FIG. 2 is an explanatory diagram of a configuration example of the color measurement device 200. A colorimetric sensor 5 for quantitatively measuring the color of a color pattern is held by a sensor holder 6, and the sensor holder 6 is supported by a support plate 7. The sliding member 8 provided on the bottom surface of the sensor holding body 6 is in contact with the support plate 7, and the loop-shaped belt 9 locked to the sensor holding body 6 is a motor pulley located on the back side of the paper surface in FIG. 11 and an idler pulley 12 located on the front side of the paper surface in the figure. When the motor pulley 11 is rotated by the motor 10, the sensor holder 6 is reciprocated in the sheet width direction (front and back direction in FIG. 2) via the belt 9. During the movement, the posture accuracy of the colorimetric sensor 5 with respect to the pressing surface 7 a of the support plate 7 is maintained via the support plate 7, the sliding member 8, and the sensor holding body 6. A drying duct 13 and a blower fan 14 capable of varying the wind speed are provided downstream of the colorimetric sensor 5 in the sheet conveyance direction (arrow A direction). The wind generated by the blower fan 14 is sent to the drying duct 13, and the wind blown from the drying duct 13 is uniformly applied toward the surface of the sheet 1 on which the color patch is printed, thereby promoting the drying of the color patch. Is done.

  A sheet discharge guide 16 is installed immediately below the support plate 7, and the sheet 1 is conveyed through an opening between the pressing surface 7 a and the sheet discharge guide 16. The colorimetric sensor 5 moves on the support plate 7 in the sheet width direction, scans the color patches printed on the sheet 1, and measures the color patches through the slits 7 b provided on the support plate 7.

  The colorimetric sensor 5, sensor holder 6, support plate 7, sliding member 8, belt 9, motor 10, motor pulley 11, idler pulley 12, drying duct 13, and blower fan 14 constitute an integral unit. Hereinafter, this is referred to as “colorimetric unit U”.

  Next, a series of operations of printing, colorimetry, and paper discharge will be described with reference to FIGS.

  The sheet 1 is nipped by the conveying roller pair 2 and is intermittently conveyed in the direction of arrow A, and the patch section P, which is a color patch, is printed by the printing unit 3 (step S1). The printing unit 3 prints an image including a color patch by applying ink to the sheet 1. For example, the printing unit 3 may be configured to use an inkjet print head capable of ejecting ink. Inkjet print heads eject ink using ejection energy generating elements such as electrothermal conversion elements (heaters) and piezo elements. When the electrothermal conversion element is used, the ink is foamed by the heat generation, and the ink can be ejected from the ejection port at the tip of the nozzle using the foaming energy. The printing method of the printing unit 3 is arbitrary, and may be a printing method such as a so-called serial scan method or a full line method. In the case of the serial scan method, an image is printed by repeating the sheet conveyance in the sheet conveyance direction and the scan of the print head in the direction intersecting the sheet conveyance direction. Further, in the case of the full line method, an image is printed while a sheet is continuously conveyed using a long print head extending along the sheet width direction. The print unit 3 can print a color image using a plurality of colors of ink. In this case, a patch row in which patches for each ink color are arranged in a grid pattern can be printed as a color patch. The form of the color patch is not specified and is arbitrary.

  FIG. 3A shows a state when the printing of the patch row P is finished. Depending on the length of the patch row P to be printed in the sheet conveyance direction, the leading edge of the sheet 1 is conveyed downstream in the sheet conveyance direction along the sheet discharge guide 16 (step S2).

  As shown in FIG. 3B, the sheet 1 on which the patch row P is printed is transported downstream in the sheet transport direction along the paper discharge guide 16, and the rear end of the patch row P faces the drying duct 13. When entering the dryable area, the conveyance of the sheet is stopped. Thereafter, the blower fan 14 is operated, and the patch row P is dried by a wind from the drying duct 13 for a predetermined time (step S3).

  Next, as shown in FIG. 3C, when the sheet 1 is conveyed to the upstream side in the sheet conveying direction and the rear end of the dried patch row P is positioned directly below the colorimetric sensor 5, the sheet 1 Is stopped (step S4). Thereafter, the colorimetric sensor 5 is operated to measure the color of the patch row P for each row (step S5). When there is a patch row at a position beyond the dryable region of the drying duct 13, the operations of FIGS. 3B and 3C are repeated for the patch row that has not been dried (step S6). After the drying and colorimetry of all the patch rows are completed, the sheet 1 is cut by the cutter 4 and then discharged (step S7).

  FIG. 4 shows an example of the transition of the color difference in the same color ink. The horizontal axis of FIG. 4 indicates the elapsed time after the ink droplet has landed on the sheet, and the vertical axis indicates the color difference ΔE of the ink droplet. Here, the color difference ΔE is based on the color of the ink when the ink droplet is sufficiently dried after a predetermined time has elapsed since the ink droplet landed on the sheet. Since the ink droplets landed on the sheet contain moisture and floating solvent, the color changes in the drying process. Therefore, as shown in FIG. 5, the color difference is large immediately after the landing of the ink droplet, and the color difference decreases with time. The decreasing tendency varies depending on the temperature and humidity of the usage environment of the printing apparatus. For example, as compared with the case of the normal temperature and normal humidity environment as shown by the curve C1 in FIG. 5, the curve in the same diagram is obtained in the high temperature and low humidity environment where the ink is easily dried (in an environment where the degree of difficulty in drying is low). As in C2, a rapid decrease in color difference ΔE can be seen in a short time. On the other hand, in a low-temperature and high-humidity environment where the ink is difficult to dry (in an environment where the degree of difficulty in drying is high), as shown by a curve C3 in FIG. . Such environmental temperature and environmental humidity are factors that vary the drying effect of the ink, that is, factors that vary the difficulty of drying the ink. In addition, the type of ink, the print density, the type of sheet, and the like can also be cited as the variation factors of the ink drying effect. Also, in a printing device equipped with a colorimetric function, the time from colorimetric patch printing to colorimetry changes depending on the printing speed of the colorimetric color patch (hereinafter also referred to as “colorimetric patch”). Therefore, the printing speed is also a variable factor of the ink drying effect.

A colorimetric patch is measured by the drying unit when τ is a variation coefficient (variation coefficient of the degree of difficulty of drying) corresponding to the variation factor of the drying effect of the ink (a variation factor of the degree of difficulty of drying the ink). The drying effect E brought about is expressed by the following equation (1).
E = τεt (1)
Here, ε is the drying capacity of the drying section, and t is the drying time.

  The drying effect E varies according to a variation coefficient τ due to a variation factor. Therefore, in order to stably acquire the color information of the colorimetric patch, it is necessary to control the drying capacity and / or the drying time of the drying unit according to the variation coefficient τ.

  In the following, for convenience of explanation, the variation factor of the drying effect is only an environmental factor. When the variation coefficient τ in an environment of normal temperature and humidity is 1, the variation coefficient τ is τ <1 in an environment (for example, high temperature and low humidity) in which the colorimetric patch is more easily dried. Therefore, in the configuration of the drying section that is dried by blowing as described above, if the drying conditions such as the blowing volume, drying time, and blowing temperature in a high-temperature and low-humidity environment are the same as those at normal temperature and humidity, measurement is performed. Color patches will be overdried. In this case, the color measurement patch can be appropriately dried by shortening the drying time or reducing the air flow rate, and accurate color information of the color measurement patch can be acquired. Further, it is possible to improve the throughput by shortening the drying time, and it is possible to reduce the noise or to save the power by suppressing the air volume and the air temperature.

  On the other hand, the variation coefficient τ is τ> 1 in an environment (for example, low temperature and high humidity) in which the colorimetric patch is more difficult to dry than in an environment of normal temperature and humidity. Therefore, in the configuration of the drying section that is dried by blowing as described above, when the drying conditions such as the blowing amount, drying time, and blowing temperature in a low temperature and high humidity environment are the same as those at normal temperature and normal humidity, The colorimetric patch is insufficiently dried. In this case, by increasing the drying time or increasing the air flow rate, the colorimetric patch can be appropriately dried to obtain accurate color information of the colorimetric patch. Moreover, it becomes possible to dry without reducing the throughput by increasing the blowing amount or raising the blowing temperature.

  The drying unit of this example includes a blower fan 14, a pressure chamber in the drying duct 13 that takes in air sucked by the blower fan 14, and a slit 15 that releases the air taken into the pressure chamber to the outside. Yes. As means for controlling the drying conditions by such a drying section, there are control of the rotational speed of the blower fan 14 by pulse width modulation (PWM) or control of changing the opening width of the slit 15 (variable control of slit width). The slit width variable control is wind pressure control that increases the wind speed by narrowing the opening area of the slit 15 and weakens the wind speed by widening it. As described above, the drying conditions such as the drying time by the drying unit and the drying effect per unit time can be changed.

Actually, the variation factor of the drying effect is related to the combination of each weighted variation factor because the ink color, print density, sheet type, printing speed, etc. are related to the variation coefficient τ in addition to the environmental factors. To determine the value of the coefficient of variation τ. However, the drying effect E is not limited to the linear function of the drying time t and the drying capacity ε of the drying section, but may be expressed by a quadratic function such as the following expressions (2), (3), and (4). .
E = τε ² t (2)
E = τεt ² (3)
E = τε ² t ² (4)

  Thus, the drying effect E, the drying time t, and the drying capacity ε may be in a relationship of a primary expression or a secondary expression.

  FIG. 5 is an explanatory diagram of the drying process for the patch row P. In the drying process of this example, the operation of transporting the sheet 1 on which the patch row P is printed to the dryable area of the drying unit and the operation of drying the patch row P are one step. The number of patches in the patch row P that can be dried in one process is Y / a (the fractional part is rounded down), where a is the length of one patch and Y is the length in the transport direction of the dry region. If the length of the patch row P in the transport direction is L, the drying step N = L / Y (rounded up after the decimal point) is performed on the patch row P. Thus, the patch row P is dried in a plurality of portions.

When the drying capacity of blowing drying is ε _a and the drying capacity of natural drying is ε _n , as shown in FIG. 6A, in the first drying step of blowing and drying the A region of the patch row P for t ₁ hour, The drying effect E _a1 of the A region is E _a1 = τε _a t ₁ . In this first drying process, the B region and the C region are naturally dried for t ₁ hours during which the A region is blown dry, and the drying effect E _b1 by the natural drying of the B region is E _b1 = τε _n t ₁ . , The drying effect E _c1 by the natural drying of the C region is E _c1 = τε _n t ₁ .

Thereafter, the area A is conveyed to the colorimetric position of the colorimetric sensor 5, and the patch row in the area A is measured. Then conveying the B region by a second drying step to the position of the drying section, the B region t for ₂ hours blow drying. In the B region and the C region, the drying effect by natural drying has already been obtained in the first drying step. Therefore, drying effect E _b2 of the region B in the second drying _{step, E b2 = E b1 + τε} a t 2 , and the drying effect E _c2 by natural drying of the C region becomes _{E c2 = E c1 + τε n} t 2 . In addition, since printing of the patch row P is performed from the C area toward the A area, there is a print time difference between these areas, and the B area is larger than the A area, and the C area is larger than the B area. A drying effect is obtained. Therefore, t ₁ > t ₂ can be satisfied, and when there are N drying steps, t _N-1 > T _N is satisfied, and thus it is possible to shorten the drying time and improve the throughput. Become.

  FIG. 7 is a block configuration diagram of a control system of the printing apparatus 100. A CPU (control unit) 300 controls the entire apparatus including printing, drying, and colorimetric operations according to a control program stored in the ROM 301. The CPU 300 receives print data, print mode setting information, and the like from the host computer (host device) 302 via the input interface 303. The CPU 300 can write and read print data to and from the RAM 304. The CPU 300 includes print data and print mode information from the host computer 302, time information from the time measurement unit 400 that measures the elapsed time after the end of printing, temperature and humidity information from the thermohygrometer 24, and the colorimetric sensor 5. Colorimetric data from is input. Based on these pieces of information, the CPU 300 controls the print head 305, the blower fan 14, the driving unit 17 of the color measurement unit U, and the motors 306, 307, and 10. The motor 306 is a sheet conveying motor 306 for driving the conveying roller 2, the motor 307 is a carriage motor for moving a carriage on which the print head 305 is mounted, and the motor 10 drives the motor pulley 11. 2 in the motor.

  When print data, print mode setting information, and the like are transferred from the host computer 302 to the printing apparatus 100, the CPU 300 determines a print control method according to the print mode setting information, and starts printing the colorimetric patch P. When the printing is completed, the colorimetric patch P is dried, and then the colorimetric sensor 5 sequentially reads the colorimetric patch P line by line. After the printing operation is completed, the ink mist in the printing apparatus 100 is completely collected by a mist collecting mechanism (not shown), and then the driving of the blower fan 14 is started. The collection time required until the ink mist is completely collected depends on the type and size of the sheet, the facing distance between the print head 305 and the sheet 1, the density of the print image, temperature, and humidity. Therefore, a table in which these factors are associated with the collection time is prepared in advance in the ROM 301, and the collection time is determined based on the table.

  After the colorimetric patch P is dried for a predetermined time, the sensor holder 6 on which the colorimetric sensor 5 is mounted is moved by the motor 10, and the colorimetric sensor 5 performs colorimetry by dividing the colorimetric patch P by one line. The calorimetric data is transferred to the CPU 300. Colorimetric data is acquired by causing the colorimetric sensor 5 to scan one or more lines of the colorimetric patch P within the dryable region. After the completion of the acquisition of the colorimetric data by the scanning, the undried area of the color patch P is dried in the dryable area, and one or more lines of the colorimetric patch P in the dryable area are then dried. Then, the colorimetric data is obtained by scanning the colorimetric sensor 5. By repeating such drying and colorimetric operations, colorimetric data for the entire area of the colorimetric patch P is acquired and stored in the RAM 304 as colorimetric information. After the color measurement of the color measurement patch P is finished, the blower fan 14 is stopped, the sheet 1 is conveyed to the cutting position of the cutter 4, the sheet 1 is cut by the cutter 4, and the cut sheet is discharged. The acquired colorimetric information is sent to the host computer 302, and thereafter used as color correction information when an image is printed.

(Other embodiments)
The printing mode, printing method, and printing unit for the colorimetric patch, and the colorimetric method and colorimetric unit for the colorimetric patch are not specified in the above-described embodiment and are arbitrary. Moreover, the drying method is also arbitrary and may be a method of drying using warm air or the like. In short, it suffices if the drying conditions for the area can be changed according to the degree of difficulty in drying the area of the sheet on which the image for colorimetry is printed with ink. “Drying difficulty” is an index indicating the degree of difficulty in drying an area to which ink has been applied. For example, as described above, drying is easy in a high-temperature and low-humidity environment. Below, it becomes difficult to dry. Such “drying difficulty” depends on various factors such as the print speed of the colorimetric image, the print density of the image, the type of sheet, the type of ink, and the elapsed time since the image was printed. Therefore, the drying conditions may be changed according to these factors. Moreover, as drying conditions, various conditions can be changed according to the drying method. For example, in the case of a method of drying by applying air, the air blowing amount, the blowing time, the blowing temperature, etc. are changed. Can do.

DESCRIPTION OF SYMBOLS 1 Sheet 2 Conveyance roller 3 Print part 5 Colorimetric sensor 13 Drying duct 14 Blower fan

Claims (8)

A print unit that prints an image by applying ink to the sheet;
A colorimetric unit that performs colorimetry on the image printed by the print unit;
A drying unit that dries an area of the sheet on which the image is printed before the colorimetric unit measures the image;
A control unit that changes the drying conditions of the region by the drying unit according to the degree of difficulty in drying the region where the image is printed;
A printing apparatus comprising:   The control unit prints the temperature in the usage environment of the printing apparatus, the humidity in the usage environment of the printing apparatus, the printing speed of the image, the print density of the image, the type of the sheet, the type of ink, and the image. And controlling at least one of the drying time of the region by the drying unit and the drying effect per unit time according to the degree of difficulty in drying the region, which varies depending on at least one of the elapsed time since the last time. The printing apparatus according to claim 1. The drying unit divides the image into a plurality of parts and dries,
The control unit shortens the drying time of the drying unit for the portion of the image to be dried later by the drying unit than the drying time of the drying unit for the portion of the image previously dried by the drying unit. The printing apparatus according to claim 1, wherein the printing apparatus is a printer.   The variation coefficient τ of the difficulty of drying of the region, the drying time t of the region by the drying unit, and the drying effect E of the region by the drying unit are in a relationship of a primary expression or a secondary expression. The printing apparatus according to claim 1, wherein the printing apparatus is a printer.   The variation coefficient τ of the difficulty level of drying in the region is τ = 1 when the use environment of the printing apparatus is normal temperature and normal humidity, τ <1 when high temperature and low humidity, and τ> 1 when low temperature and high humidity. The printing apparatus according to claim 1, wherein the printing apparatus is a printing apparatus. The drying unit causes a flow of air to be dried in the region of the sheet by rotation of a blower fan,
The printing apparatus according to claim 1, wherein the control unit controls the number of rotations of the blower fan of the drying unit. The drying unit generates a flow of air for drying in the region of the sheet, a pressure chamber that takes in air sent from the blower fan, and discharges air taken into the pressure chamber to the outside. Including a slit,
The printing apparatus according to claim 1, wherein the control unit can change an opening area of the slit. The print unit, the color measurement unit, and the drying unit are provided in that order from upstream to downstream along the direction in which the sheet is conveyed,
The sheet on which the color measurement image is printed by the printing unit is sent to the downstream side and dried by the drying unit, and then the sheet is sent back to the upstream side to obtain the color measurement image. 8. The printing apparatus according to claim 1, wherein the color measurement unit performs color measurement, and the color-measured sheet is conveyed and discharged toward the downstream side.

Images