JP2014226577A - Ink-jet printer, and print module of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To print on a print medium with irregularity on a surface by one print operation while maintaining a constant gap between the surface of the print medium and a print head.SOLUTION: A head of a print medium 31 is conveyed to a position of a distance sensor 23 by a conveying belt 113. A carriage 2 is reciprocated in a main scanning direction as indicated by an arrow A2, and a distance from the carriage 2 to a surface of the print medium 31 is measured by the distance sensor 23. As a result, a length in the main scanning direction and a height of a projection part of irregularity (e.g. buttons and pockets in a case of clothes) on the surface of the print medium 31 are measured. When an image is printed on the print medium 31, a print head 21 is slid based on a measurement value of the irregularity so that the distance from the carriage 2 to the surface of the print medium 31 becomes constant irrespective of the irregularity on the surface of the print medium 31.

Description

  The present invention relates to an inkjet printing apparatus and a printing module thereof.

  Universal inkjet is a module in which a printing unit (printing head, carriage, head maintenance unit, ink supply unit, carriage driving unit, etc.) of an inkjet printing apparatus is formed as a printing module. An image printing system can be configured by combining this printing module and a transport device corresponding to various printing media (clothes, T-shirts, CD / DVDs, credit cards, ID cards, etc.). Moreover, these image printing systems are utilized for industrial applications. In order to ensure high printing accuracy with such a highly versatile printing module, it is important to properly maintain gaps between the surfaces of various printing media and the print head.

  However, with such a highly versatile printing module, the surface of various printing media (in the case of printing media made of cloth such as clothes and T-shirts, there are irregularities due to accessories such as buttons and pockets on the surface) and Therefore, it is difficult to keep the gap between the printing head and the gap outside the proper value, so that the printed image accuracy deteriorates. In addition, when the unevenness of the unevenness of the surface of the print medium is larger than the set gap, there is also a problem that the print medium comes into contact with the print head, leading to a print medium conveyance failure or a print head damage. Furthermore, the fixing property of the ink ejected from the print head may differ and the color may change depending on the surface roughness of the material of the printing medium (for example, silk, cotton, and pile).

  As an apparatus which copes with such a problem, there is an ink jet type fabric printing apparatus described in Patent Document 1. This inkjet fabric printing apparatus includes an inkjet head that ejects ink onto the surface of a fabric, and a first platen that has a first work surface on which the fabric can be set, and the inkjet head and the first platen include An inkjet fabric printing apparatus that prints a desired image on the surface of the fabric set on the first work surface of the first platen by relatively moving while maintaining a predetermined distance. And a second platen having a second work surface on which the pocket portion can be set.

  However, in this inkjet fabric printing apparatus, the second platen is detachably provided at a height different from that of the first platen, and when printing the pocket portion, the distance between the inkjet head and the second platen is small. Since it is configured to be the predetermined distance, when printing a T-shirt having a pocket portion, it is necessary to perform printing of the pocket portion and printing of other portions by separate printing operations. . In addition, it is impossible to suppress a change in the hue of a printed image that occurs as a result of gap adjustment for unevenness other than a pocket such as a button or a difference in ink fixability due to a difference in the material of a print medium.

  The present invention has been made to solve such a problem, and the object of the present invention is to maintain a constant gap between the surface of the print medium and the print head with respect to a print medium having an uneven surface. However, it is possible to print with a single printing operation.

  A printing module according to the present invention is a printing module that constitutes an inkjet printing apparatus in combination with a printing medium conveying apparatus, and before the print head discharges ink toward the printing medium, An unevenness detecting means for detecting unevenness on the surface of the print medium in a non-contact manner, and a gap adjusting means for changing a gap between the print medium and the print head according to the unevenness detected by the unevenness detecting means, A printing module.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to print with one printing operation, keeping the gap between the surface of a printing medium and a print head constant with respect to a printing medium with an uneven surface.

1 is a perspective view illustrating a schematic configuration of a printing module according to a first embodiment of the present invention. It is a block diagram for demonstrating the structure of the control system of the inkjet printing apparatus which has a printing module which concerns on the 1st Embodiment of this invention. FIG. 2 is a diagram illustrating a schematic configuration of a carriage in the printing module according to the first embodiment of the present invention. It is a figure for demonstrating the method to detect the unevenness | corrugation of the surface of a printing medium with the printing module which concerns on the 1st Embodiment of this invention. The figure for demonstrating the method of detecting the unevenness | corrugation of the surface of a printing medium with the printing module which concerns on the 1st Embodiment of this invention, and adjusting the gap between the ejection surface of the ink of a printing head, and the surface of a printing medium. It is. It is a figure which shows schematic structure of the carriage in the printing module which concerns on the 2nd Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
<Schematic configuration of printing module>
FIG. 1 is a perspective view showing a schematic configuration of a printing module according to the first embodiment of the present invention.

  The printing module 1 includes a carriage 2 in which a print head is stored. The print medium supplies ink from the ink cartridge 3 to the print head and is transported in the sub-scanning direction by a transport device (not shown). Print on the surface. At this time, power is transmitted from a main scanning motor (not shown) to the driving belt 4 that drives the carriage 2, and the carriage 2 slides left and right (main scanning direction) on the main rod 5 and the guide rod 6. The maintenance supply unit 7 performs head cleaning maintenance by sucking dry ink from the discharge port of the print head or skewing the discharge port surface with a rubber-made pad.

<Control system for inkjet printer>
FIG. 2 is a block diagram for explaining the configuration of the control system of the ink jet printing apparatus having the printing module according to the first embodiment of the present invention. In this figure, the same reference numerals as those in FIG. 1 are assigned to portions corresponding to those in FIG.

  In this figure, a carriage 2, a head driver 110, and a main scanning motor 111 are mounted on the printing module 1, and a sub scanning motor 112 and a conveying belt 113 are mounted on a printing medium conveying device. The controller 100 is separate from the printing module 1 and the printing medium conveyance device, and is configured to be electrically connectable.

  The carriage 2 is provided with a print head 21, a head slide motor 22, and a distance sensor 23. The controller 100 includes a head control unit 101, a head slide motor driving unit 102, a main scanning motor driving unit 103, a distance sensor driving unit 104, and a sub scanning motor driving unit 105.

  The head controller 101 controls the head driver 110. The head driver 110 drives the print head 21 according to the control of the head control unit 101 and discharges ink from the nozzles.

  A head slide motor driving unit 102 as a gap adjusting unit drives the head slide motor 22. The head slide motor 22 moves a slider (described later in detail) on which the print head 21 is placed in a direction perpendicular to the surface of the print medium, so that the space between the surface of the print medium and the ink ejection surface of the print head 21 is increased. Change the gap.

  The main scanning motor driving unit 103 drives the main scanning motor 111 to move the carriage 2 in the main scanning direction. The sub-scanning motor driving unit 105 drives the sub-scanning motor 112 to rotate the conveyance belt 113 that conveys the print medium while adsorbing it.

  The distance sensor driving unit 104 drives the distance sensor 23. A distance sensor 23 serving as a distance measuring unit constituting the unevenness detecting unit is a distance sensor that measures the distance from the ink ejection surface (nozzle tip) of the print head 21 to the surface of the print medium in a non-contact manner. The distance sensor 23 includes, for example, a light emitting element and a light receiving element, and calculates a distance from a time difference between light emission toward the surface of the print medium and reception of reflected light from the surface of the print medium. The time difference may be calculated by a CPU (not shown) in the controller 100.

<Schematic configuration of carriage>
FIG. 3 is a diagram illustrating a schematic configuration of a carriage in the printing module according to the first embodiment of the present invention. Here, FIG. 3A is a top view and FIG. 3B is a side view. In this figure, the same reference numerals as those in FIG. 1 are assigned to the portions corresponding to those in FIG.

  In the carriage 2, two print heads 21-1 and 21-2 are stored as the print head 21. A distance sensor 23 is disposed on the upper surface of the carriage 2.

  Two nozzle rows 21-1a and 21-1b extending in the sub-scanning direction are provided on the upper surface of the print head 21-1, and two nozzles extending in the sub-scanning direction are provided on the upper surface of the print head 21-2. Rows 21-2a and 21-2b are provided. The nozzle arrays 21-1a, 21-1b, 21-2a, and 21-2b eject, for example, Y (yellow), M (magenta), C (cyan), and K (black) inks.

<Detection of irregularities on the surface of print media>
FIG. 4 is a diagram for explaining a method for detecting irregularities on the surface of the print medium by the print module according to the first embodiment of the present invention. Here, in order to explain the relationship between the carriage and the print medium, the entire configuration of the print module 1 is omitted.

Hereinafter, the flow of control will be described.
First, the leading end of the print medium 31 is transported to the position of the distance sensor 23 by the transport belt 113 (procedure 1).

  Next, the carriage 2 is reciprocated in the main scanning direction as indicated by an arrow A2, and the distance sensor 23 measures the distance from the ink ejection surface of the print head 21 to the surface of the print medium 31 over one line of the print medium 31 ( Procedure 2). That is, irregularities on the surface of the print medium 31 are detected in units of lines. As a result, data indicating the height of the convex portion (such as a button or pocket in the case of clothing) and the position in the main scanning direction is obtained in units of lines. Note that the carriage 2 moves below the print medium 31 during the reciprocating operation.

  When printing an image on the surface of the print medium 31, the controller 100 determines the ink discharge surface of the print head 21 based on the detection result of the surface unevenness of the print medium 31 regardless of the surface unevenness of the print medium 31. The print head 21 is slid so that the gap (distance) with the surface of the print medium 31 is constant. Details of this procedure will be described later with reference to FIG.

<Gap adjustment according to the unevenness of the surface of the print medium>
FIG. 5 illustrates a method for detecting the unevenness of the surface of the print medium by the printing module according to the first embodiment of the present invention and adjusting the gap between the ink ejection surface of the print head and the surface of the print medium. It is a figure for doing. Here, FIG. 5A is a top view and FIG. 5B is a side view. In this figure, the same reference numerals as those in FIG. 3 are assigned to the portions corresponding to those in FIG.

  A slider 25 is attached to the lower surface of the print head 21 (the right end surface in FIG. 5A). The slider 25 is coupled by a rotating shaft and gears of the head slide motor 22 and slides up and down as the head slide motor 22 rotates forward and backward.

  In the present embodiment, the standard value of the gap between the ink ejection surface of the print head 21 and the surface of the print medium 31 is 0.8 mm. Further, the gap adjustment by the slider 25 is possible in units of 0.1 mm.

Hereinafter, the flow of control will be described.
First, before the print head 21 ejects ink toward the print medium 31, the procedure 1 and the procedure 2 described with reference to FIG. 4 are executed. When a convex portion due to an accessory such as a pocket is detected on the surface of the print medium 31 by these procedures, a gap for printing on the convex portion by the next movement of the carriage 2 is calculated, and the control parameter is set to the controller 100. Is set in a storage unit (not shown) such as a non-volatile memory (procedure 3).

  For example, if the pocket fabric thickness (projection height) is 0.6 mm and the width (main scanning direction length) is 100 mm, the gap until the print head 21 reaches the pocket position is set to the standard 0.8 mm. Then, the control parameter for maintaining the gap at 0.8 mm is set by sliding the print head 21 downward by 0.6 mm when it reaches.

  In order to move the print medium 31 to the position of the next print area, the conveyor belt 113 is driven (procedure 4). Based on the control parameters set in the storage unit in step 3, the print head 21 is moved during the period in which the print head 21 faces the pocket during the period in which the carriage 2 moves in the main scanning direction for ink ejection. The gap is maintained at the standard 0.8 mm by sliding down 0.6 mm (Procedure 5).

  In parallel with the procedure 5, the procedure 2 is executed in order to detect the unevenness of the next print area on the print medium 31 (procedure 6). By repeating steps 3 to 6, an image is printed on the surface of the print medium 31.

  Note that the unevenness on the print medium 31 is detected for each line, but an image using the result may be printed for each line or for each of a plurality of lines. That is, the length of the print area in the sub-scanning direction may be one line or multiple lines. In the case of printing for each of a plurality of lines, the unevenness detection for each line is performed a plurality of times, and then the printing of the plurality of lines is performed.

  Further, the two print heads 21-1 and 21-2 may be slid simultaneously with a common slider, or may be individually slid with another slider. The ability to adjust the gap with respect to the unevenness is enhanced by sliding individually.

<Corresponding to unevenness of height difference exceeding the gap adjustable range>
Existence of buttons on the print medium 31 having a height outside the standard exceeding the maximum value (for example, 5 mm) of the gap between the ink ejection surface of the print head 21 and the print medium 31 due to restrictions on the mechanism of the print module 1 If is detected, the following control is performed.

  An unprintable height with respect to a display device (not shown) that displays the error status of the print module 1 by stopping the transport operation of the print medium 31 by the transport device for printing the next print area. Send a message to indicate that there are attachments. The conveyance stopping means for stopping the conveyance operation of the print medium 31 is realized by the sub-scanning motor driving unit 105 stopping the rotation of the sub-scanning motor 112 and stopping the rotation of the conveyance belt 113. The means for sending the message may be a general software control process that is normally used.

  As described above in detail, according to the printing module 1 according to the first embodiment of the present invention, the gap between the surface of the print medium 31 and the ink ejection surface of the print head 21 is kept constant, It is possible to print convex portions such as clothes pockets and buttons and other portions by printing operation. In addition, it is possible to prevent the conveyance failure of the print medium 31 and the breakage of the print head 21 due to the contact between the unevenness of the surface of the print medium 31 and the print head 21.

[Second Embodiment]
FIG. 6 is a diagram showing a schematic configuration of a carriage in the printing module according to the second embodiment of the present invention. Here, FIG. 6A is a top view and FIG. 6B is a side view. Here, the same reference numerals as those in FIG. 3 are assigned to portions corresponding to those in FIG.

  In the carriage 2 according to the present embodiment, a distance sensor / reflectance sensor 24 is provided in place of the distance sensor 23 in the carriage 2 according to the first embodiment as the reflectance measuring unit constituting the surface roughness detecting unit. Yes.

  The distance sensor / reflectance sensor 24 is similar to the distance sensor 23 in the first embodiment, in addition to the function of measuring the distance from the ink ejection surface of the print head 21 to the surface of the print medium 31 in a non-contact manner. It has a function to measure the reflectance of the material without contact. The reflectance is measured (calculated) from an intensity difference between light emission toward the surface of the print medium 31 and reception of reflected light from the surface of the print medium 31. That is, in the distance sensor / reflectance sensor 24, the distance sensor and the reflectance sensor share the light emitting element and the light receiving element. The measurement result of the reflectivity is performed based on the correspondence relationship between the reflectivity and surface roughness of various materials acquired in advance.

  In the present embodiment, based on the measurement result of the reflectance by the distance sensor / reflectance sensor 24, the correspondence between the reflectance of various materials acquired in advance and the surface roughness, the material of the print medium 31 is determined. Detect surface roughness. When the surface roughness exceeds a predetermined threshold, when the carriage 2 moves, the viscosity of the ink is determined from the leading nozzle row, that is, the nozzle row at the tip in the main scanning direction (here, the nozzle row 21-1a). It is comprised so that the additive to reduce may be discharged. The head controller 101 corresponds to the additive discharge control means.

  The schematic configuration of the printing module according to this embodiment is the same as that of the first embodiment (FIG. 1). Further, the configuration of the control system is such that a distance sensor / reflectance sensor drive unit is provided instead of the distance sensor drive unit 104 in the first embodiment (FIG. 2). Therefore, in the following description, the first embodiment is referred to for the same or corresponding parts as the first embodiment.

  Hereinafter, a method for detecting the roughness of the surface of the printing medium 31 by the printing module 1 according to the present embodiment and discharging an additive for reducing the viscosity of the ink will be described.

  Of the ink cartridge 3, the cartridge that supplies ink to the nozzle row 21-1a is filled with an additive that lowers the viscosity of the ink instead of the ink. The cartridges that supply ink to the other nozzle rows 21-1b, 21-2a, 21-2b are filled with ink.

  The reflectance for each print medium 31 of various materials (for example, cotton, silk, pile fabric, etc.) is measured in advance by the distance sensor / reflectance sensor 24, and stored in a nonvolatile memory (not shown) in the controller 100. Save it on the device.

  Further, a threshold value that is a criterion for determining whether or not to discharge the additive from the nozzle array 21-1 a is determined from a prior evaluation based on the performance of the distance sensor / reflectance sensor 24. For example, if the reflectance of silk is 90% or more, the reflectance of cotton is 90% or less and 70% or more, and the reflectance of pile fabric is less than 70%, the threshold value is 70%, and the measured value of reflectance is 70%. When the amount is less than that, the additive is discharged.

  That is, when it is determined from the measured value of the reflectance of the print medium 31 that the print medium 31 has a fuzzy surface such as a pile ground, the viscosity of the ink is reduced from the nozzle row 21-1a during printing. The additive is discharged. By this treatment, it is possible to improve the ink adhesion by reducing the viscosity of the ink that is usually difficult to adhere to the surface of the print medium 31 having a high ink viscosity and a fuzzy surface.

  For example, an ink having a viscosity of 8 mPa · s adheres well to cotton but does not adhere well to pile fabric. Therefore, by adding an additive, the viscosity of the ink is lowered to 2/3 to improve the adhesion of the ink to the pile ground. The threshold value (discharge amount of the additive) is determined from a prior evaluation based on the performance of the ink used in the printing module 1. The additive is not discharged to a printing medium made of a material that does not cause any problem of ink adhesion such as silk or cotton.

Hereinafter, the flow of control will be described.
The top of the print medium 31 is transported to the position of the distance sensor / reflectance sensor 24 by the transport belt 113 (procedure 11).

  The distance sensor / reflectance sensor 24 measures the distance from the ink ejection surface of the print head 21 to the surface of the print medium 31 and also measures the reflectivity of the surface of the print medium 31 (procedure 12).

  From the measurement result of the reflectance and the reflectance data of the printing medium of various materials that have been measured and stored in advance, the material of the printing medium is specified and it is determined whether an additive is necessary ( Procedure 13).

The conveyance belt 113 is driven to align the portion of the print medium 31 measured in step 12 with the position of the print head 21 (step 14).
When the material of the print medium 31 requires an additive, the additive is ejected from the nozzle row 21-1a and applied to the surface of the print medium 31, and the nozzle rows 21-1b, 21-2a, and 21 are applied. -B is ejected to print an image on the print medium 31 (procedure 15).

In parallel with the procedure 15, for the next print area in the print medium 31, the distance sensor / reflectance sensor 24 measures the distance from the ink ejection surface of the print head 21 to the surface of the print medium 31, and the print medium The reflectance of the surface of 31 is measured (procedure 16).
By repeating steps 14 to 16, an image is printed on the print medium 31.

  As described above in detail, according to the printing module 1 according to the second embodiment of the present invention, the gap between the surface of the print medium 31 and the ink ejection surface of the print head 21 is kept constant, It is possible to print convex portions such as clothes pockets and buttons and other portions by printing operation. In addition, it is possible to suppress a change in the hue of the printed image that occurs as a result of the difference in the ink fixability due to the difference in the material of the print medium 31.

  Note that the printing module 1 according to the second embodiment includes the distance sensor / reflectance sensor 24. However, instead of the distance sensor / reflectance sensor 24, a reflectance sensor (only a reflectance sensor without a distance sensor is provided). May be provided). In the first embodiment and the second embodiment, the number of print heads may be three or more (print heads 21-1, 21-2, 21-3,...). Further, the print heads 21-1, 21-2, etc. may be provided with three or more nozzle rows.

  DESCRIPTION OF SYMBOLS 1 ... Printing module, 21 ... Print head, 22 ... Head slide motor, 23 ... Distance sensor, 24 ... Distance sensor and reflectance sensor, 25 ... Slider, 31 ... Print medium, 101 ... Head control part, 102 ... Head slide motor Driving unit 105... Sub scanning motor driving unit 112. Sub scanning motor 113 113 Conveying belt.

JP 2004-291399 A

Claims (9)

A printing module that constitutes an inkjet printing apparatus in combination with a printing medium conveying apparatus,
A print head;
Unevenness detecting means for detecting the unevenness of the surface of the print medium in a non-contact manner before the print head ejects ink toward the print medium;
A gap adjusting means for changing a gap between the print medium and the print head according to the unevenness detected by the unevenness detecting means;
Having a printing module. The printing module according to claim 1,
A printing module, comprising: a conveyance stopping unit that stops a conveyance operation of a printing medium by the conveyance device when a difference in height of the unevenness exceeds a maximum value of a gap that can be adjusted by the gap adjustment unit. The printing module according to claim 1 or 2,
The unevenness detecting means has a distance measuring means for measuring a distance from the print head to the surface of the printing medium, and detects the unevenness based on a measurement result of the distance measuring means. In the printing module according to any one of claims 1 to 3,
Surface roughness detection means for detecting the surface roughness of the material of the print medium in a non-contact manner before the print head discharges ink toward the print medium;
Based on the detection result of the surface roughness detection means, an additive discharge control means for discharging an additive for reducing the viscosity of the ink from the print head;
Having a printing module. The printing module according to claim 4, wherein
The surface roughness detecting means has a reflectance measuring means for measuring the reflectance of the surface of the printing medium, and the measurement results of the reflectance measuring means and the reflectance of the printing medium of various materials acquired in advance. A printing module that detects the surface roughness based on the correspondence relationship between In the printing module according to any one of claims 3 to 5,
The unevenness detecting means includes a light emitting element and a light receiving element, and measures a distance from a time difference between light emission and light reception. The printing module according to claim 5 or 6,
The surface roughness detection means includes a light emitting element and a light receiving element, and measures a reflectance from a difference in intensity between light emission and light reception. The printing module according to claim 7, wherein
The unevenness detector and the surface roughness detector share a light emitting element and a light receiving element. An ink jet printing apparatus comprising: the printing module according to claim 1; and a printing medium transport device.

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