JP2013199037A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can form an image by using a general color ink and a special color ink.SOLUTION: An image forming apparatus of an embodiment includes: a conveying mechanism for conveying a recording medium; a first recording head part mounted with an inkjet head for a general color; a first head drive mechanism for moving the first recording head part along a first guide; a second recording head part mounted with an inkjet head for a special color; and a second head drive mechanism for moving the second recording head part along a second guide. The first guide and the second guide are parallel with each other. The first recording head part and the second recording head part are independently arranged at an upstream side and a downstream side with respect to the conveying direction of the recording medium, and independently move in main scan directions by the first head drive mechanism and the second head drive mechanism on the basis of commands from a controller, respectively.

Description

  Embodiments described herein relate generally to an image forming apparatus for forming an image on a recording medium.

  For example, an ink jet printer having an ink jet recording head unit conveys a recording medium such as a sheet in a predetermined direction, and moves the recording head unit on which the ink jet head is mounted in a direction perpendicular to the sheet conveying direction. An image is formed on a recording medium by ejecting ink from the inkjet head.

  In a recording head unit that ejects a plurality of types of color ink for a color image, a plurality of inkjet heads for general colors represented by three primary colors (for example, yellow, magenta, and cyan) of subtractive color mixing (subtractive color mixing) and black Are mounted in one head holder in a line in the scanning direction. In addition, a recording head unit including a special color ink jet head that discharges special color inks such as gold, silver, fluorescent color ink, and light color ink, and the general color ink jet head has also been proposed.

  In an image using general color ink, a desired color is expressed by subtractive color mixture using ink of each color ejected onto a recording medium. On the other hand, an image with special color ink forms an image with a single ink. For this reason, in so-called surface printing, a general color image is formed on the surface of a recording medium by a general color ink jet head, and a special color image is formed thereon by a special color ink jet head. ing. On the other hand, in printing called back printing, an image of special color ink is formed on the surface of a transparent recording medium, and then an image of general color ink is formed thereon, and the formed image is recorded on a transparent recording medium. I see it from the back side of the medium.

  In either case, since the inkjet head for general colors and the inkjet head for special colors are mounted on a common head holder, the mass of the recording head portion is large and the moment of inertia is large.

JP 2009-113284 A

  The problem to be solved by the present invention is to reduce the moment of inertia of the recording head portion used during printing of general colors.

  In the embodiment, the image forming apparatus includes a transport mechanism that transports a recording medium, an ink jet head that discharges general color ink, and a first recording head unit that moves in the main scanning direction along a first guide. A first head driving mechanism for moving the first recording head portion in the main scanning direction and an ink jet head for discharging special color ink are mounted, and the recording medium is transported to the first recording head portion. A second recording head unit that is arranged in a direction apart from the first recording head unit and moves in a main scanning direction independently of the first recording head unit along a second guide parallel to the first guide; A second head driving mechanism for moving the second recording head section in the main scanning direction; and a controller for controlling the first and second recording head sections.

1 is a plan view schematically showing an image forming apparatus according to a first embodiment. FIG. 3 is a diagram schematically illustrating a recording head unit, an electric circuit, and the like of the image forming apparatus. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus. FIG. 3 is a plan view showing a state where a second recording head unit of the image forming apparatus shown in FIG. 1 has moved. FIG. 6 is a plan view schematically showing an image forming apparatus according to a second embodiment. FIG. 10 is a plan view schematically showing an image forming apparatus according to a third embodiment. FIG. 10 is a plan view schematically showing an image forming apparatus according to a fourth embodiment.

  The image forming apparatus according to the first embodiment will be described below with reference to FIGS. FIG. 1 shows an ink jet printer 10 which is an example of an image forming apparatus. An ink jet printer (hereinafter referred to as a printer) 10 includes a transport mechanism 11. The conveyance mechanism 11 includes a conveyance roller 12, a motor 13 that rotates the conveyance roller 12, and the like, and moves a sheet S that is an example of a recording medium in a conveyance direction indicated by an arrow A. An example of the sheet S is paper of a prescribed size, but it may be a transparent or opaque resin film or label.

  The printer 10 includes a first head unit 21, a second head unit 22, and an electrical configuration (shown in FIG. 3) that controls the head units 21 and 22. The first head unit 21 forms an image of a general color on the sheet S. The second head unit 22 forms an image with a special color on the sheet S.

  The “image with a general color” referred to here is an image formed by using or mixing three primary colors (for example, yellow, magenta, and cyan) that form a subtractive color mixture with black ink. “Special color image” means a single color ink, such as gold, silver, metallic, fluorescent color ink, or light color ink, that cannot be expressed with the general color ink. It is an image formed by.

  The first head unit 21 includes a first recording head unit 30 mounted with general-color inkjet heads 30a, 30b, 30c, and 30d, a first guide 35, and a first recording head unit 30. The first head driving mechanism 36 that moves along the guide 35 and the sensor 37 that detects the position of the first recording head unit 30 are provided. For example, an encoder that outputs information about a position, an optical sensor that outputs an electrical signal by a trigger arranged in advance at a specified position, or the like is used.

  The recording head unit 30 of the first head unit 21 reciprocates in the main scanning direction (the direction indicated by the arrow B) along the first guide 35. The main scanning direction is a direction perpendicular to the conveyance direction A of the sheet S. The first guide 35 extends in the main scanning direction.

  An example of the first head driving mechanism 36 includes a driving pulley 40, a driven pulley 41, a winding transmission 42 such as a timing belt stretched between these pulleys 40, 41, and the driving pulley 40. A motor 43 to be rotated and a force transmission member 44 such as a gear for transmitting the torque of the motor 43 to the driving pulley 40 are included. As the first head driving mechanism 36, for example, a driving mechanism using a ball screw and a pulse motor or a driving mechanism using a linear motor may be employed instead of using the pulleys 40 and 41 and the winding transmission body 42. .

  FIG. 2 shows a part of the first recording head unit 30 and the control electric circuit. For example, the first recording head unit 30 that ejects ink of general colors includes, for example, an inkjet head 30a for yellow (Y), an inkjet head 30b for magenta (M), and an inkjet head 30c for cyan (C). Black (K) inkjet heads 30b are arranged in a head holder 45 in a line in the main scanning direction. The first recording head unit 30 forms a color image on the surface of the sheet S by subtractive color mixture of general color inks ejected from the inkjet heads 30a, 30b, 30c, and 30d.

  As shown in FIG. 1, the second head unit 22 is disposed downstream of the first head unit 21 in the sheet S conveyance direction (indicated by an arrow A). The second head unit 22 is arranged along the second guide 55 with the second recording head unit 50, the second guide 55, and the second recording head unit 50 mounted with the inkjet head 50 a for special colors. A second head driving mechanism 56 to be moved and a sensor 57 for detecting the position of the second recording head unit 50 are provided. As the sensor 57, a sensor that outputs information about a position like an encoder, or an optical sensor that outputs an electrical signal by a trigger that is arranged in advance at a specified position is used. The second guide 55 extends in the main scanning direction (indicated by arrow C). The main scanning direction is a direction perpendicular to the conveyance direction A of the sheet S.

  An example of the second head driving mechanism 56 includes a driving pulley 60, a driven pulley 61, a winding transmission member 62 such as a timing belt stretched between the pulleys 60, 61, and a driving pulley 60. A motor 63 to be rotated and a force transmission member 64 such as a gear for transmitting the torque of the motor 63 to the driving pulley 60 are included. As the second head drive mechanism 56, for example, a drive mechanism using a ball screw and a pulse motor or a drive mechanism using a linear motor may be employed instead of using the pulleys 60 and 61 and the winding transmission body 62. .

  The second recording head unit 50 includes an inkjet head 50a that discharges the special color. The inkjet head 50 a is disposed on the head holder 65. The second recording head unit 50 moves along the second guide 55 in a direction perpendicular to the conveying direction of the sheet S (main scanning direction indicated by an arrow C in FIG. 1).

  The inkjet head 50a of the second recording head unit 50 forms an image on the sheet S by ejecting special color ink. In the second recording head unit 50 of the present embodiment, only one inkjet head 50a is mounted. For this reason, the outer shape and mass of the second recording head unit 50 are smaller than the outer shape and mass of the first recording head unit 30 on which the plurality of inkjet heads 30a, 30b, 30c, and 30d are mounted.

  The inkjet heads 30a, 30b, 30c, and 30d of the first recording head unit 30 and the inkjet head 50a of the second recording head unit 50 each eject ink by, for example, a thermal type. In the thermal method, a pressure change is generated in the ink by applying heat to the ink by a built-in heater, and the ink is ejected from the nozzle toward the sheet S by the pressure change. In addition to the thermal method, for example, an element having a piezoelectric effect (for example, a piezoelectric element) may be used, the piezoelectric element may be deformed by an electric current, and ink may be ejected from the nozzle by a pumping action based on the deformation.

  FIG. 3 is a block diagram illustrating an electrical configuration of the printer 10 according to the embodiment. The printer 10 includes a CPU (Central Processing Unit) 70 that functions as a controller. The CPU 70 is connected to a ROM (Reed Only Memory) 72, a RAM (Random Access Memory) 73, a communication interface unit 74, a display / operation driver 75, a sensor input / output port 76, and a conveyance roller motor driver via a bus line 71. 80, a first head driving motor driver 81, a second head driving motor driver 82, a general color inkjet head driver 83, a special color inkjet head driver 84, and the like are connected.

  The ROM 72 stores a program for controlling the CPU 70 and various fixed data. The RAM 73 includes various memory areas for storing various data necessary for image formation. The communication interface unit 74 controls data communication performed with an external device via a communication line (network). The display / operation driver 75 controls an operation panel 75a that also serves as a display unit. By operating the operation panel 75a, information necessary for image formation can be stored in the RAM 73 or the like. The sensor input / output port 76 is connected to various sensors (for example, position detection sensors 37 and 57). The position signal of the first recording head unit 30 detected by the sensor 37 and the position signal of the second recording head unit 50 detected by the sensor 57 are input to the CPU 70 via the sensor input / output port 76.

  The conveyance roller motor driver 80 drives the motor 13 of the conveyance mechanism 11. The first head drive motor driver 81 drives the motor 43 of the first head drive mechanism 36. The second head drive motor driver 82 drives the motor 63 of the second head drive mechanism 56. The general color inkjet head driver 83 controls the ink ejection operation of the general color inkjet heads 30a, 30b, 30c, and 30d. The special color inkjet head driver 84 controls the ink ejection operation of the special color inkjet head 50a.

  Thus, the electrical configuration of the printer 10 includes a control circuit that controls the transport mechanism 11, a control circuit that controls the first and second head drive mechanisms 36 and 56, and inkjet heads 30a, 30b, 30c, 30d, and a control circuit that controls the ink ejection operation of the special color inkjet head 50a, and functions as a control unit that controls the printing operation of the printer 10.

The outline of the image forming process by the printer 10 of the embodiment will be described below.
The sheet S stored in a sheet storage unit (not shown) is transported in the sub-scanning direction indicated by the arrow A by the transport mechanism 11 shown in FIG. When the image forming area of the sheet S reaches the first head unit 21, the first recording head unit 30 is indicated by an arrow B1 in FIG. 1 by the first head driving mechanism 36 based on a command from the CPU 70 functioning as a controller. Move in the forward direction. Then, based on the image data stored in the RAM 73 or the like, the ejection operation of the inkjet heads 30a, 30b, 30c, and 30d is controlled, so that one pass of the image with the general color ink is formed on the surface of the sheet S. The

  Printing with general color inks is color printing based on subtractive color mixing with general color inks ejected from these inkjet heads 30a, 30b, 30c, and 30d. For this reason, unless the ejection order of each color ink (color superposition order) is not constant, the hue will differ depending on the color order. Therefore, after printing for one pass, the first recording head unit 30 moves in the backward direction indicated by the arrow B2 to return to the initial position, and at the initial position until printing for the next one pass is performed. stand by. When printing for the next pass, the inkjet heads 30a, 30b, 30c, and 30d discharge while the first recording head unit 30 moves again toward the sheet S in the forward direction indicated by the arrow B1. Printing is performed with general color ink. Thus, an image by the first recording head unit 30 is formed on the surface of the sheet S.

  When forming an image with a special color, when the image formation area with the special color among the image formation areas of the sheet S reaches the second head unit 22, the second head drive mechanism 56 causes the second head drive mechanism 56 to perform the first operation. 1 is moved in the forward direction indicated by arrow C1 in FIG. 1, and the ejection operation of the inkjet head 50a is controlled based on the image data, so that one pass of special color ink on the sheet S is performed. Minute images are formed.

  Printing with the special color ink is performed by the second recording head unit 50 including a single inkjet head 50a. Therefore, unlike the first recording head unit 30, the second recording head unit 50 does not need to return to the initial position every time printing for one pass is performed. Therefore, the second recording head unit 50 stands by at the end position (stroke end) on the forward path side as shown in FIG. 4 until the next one-pass printing is performed. Then, when printing for the next one pass, the second recording head unit 50 performs printing with the special color ink ejected by the inkjet head 50a while moving in the forward direction indicated by the arrow C2. Thus, a special color image is formed by the second recording head unit 50 on the general color image. That is, the printer 10 according to the embodiment performs color printing by using the first and second recording head units 30 and 50 of the serial system that move in the scanning direction.

  In the printer 10 of the present embodiment, the first recording head unit 30 and the second recording head unit 50 can move independently of each other, so the first recording head unit 30 that reciprocates for each printing for one pass. On the other hand, the second recording head unit 50 can be moved only in the forward direction or the backward direction.

  Therefore, according to the present embodiment, it is possible to minimize the movement of the second recording head unit 50 that is less frequently used than the first recording head unit 30. That is, the energy consumption of the second recording head unit 50 required for printing for one pass can be reduced as compared with the first recording head unit 30 that reciprocates each time printing for one pass is completed. .

  In this way, special color inks are used in combination by color printing by the inkjet heads 30a, 30b, 30c, and 30d for general colors and printing using special color inks ejected from the inkjet head 50a for special colors as necessary. A texture image is formed. The printer 10 according to this embodiment is suitable for “front printing” in which an image printed on an opaque sheet is viewed from the front side of the sheet because an image of a special color ink is superimposed on a color image of a general color. In “front printing”, since the printing surface is viewed from the front side of the sheet, it is preferable to perform printing with the special color ink after printing with the general color ink as in the printer 10.

  FIG. 5 shows a printer 10A of the second embodiment. In the second embodiment, the second recording head unit 50 is disposed on the upstream side and the first recording head unit 30 is disposed on the downstream side in the conveyance direction of the sheet S indicated by the arrow A. Since the other configuration is the same as that of the first embodiment, portions common to those of the first embodiment are denoted by common reference numerals and description thereof is omitted.

  In the printer 10A of the second embodiment, after printing is performed on the surface of the sheet S with the special color ink ejected from the second recording head unit 50, the general recording ink by the first recording head unit 30 is used from above. Printing is done. For example, in the case of “back printing” in which an image is viewed from the back side of a transparent sheet or printing in which an image printed on an intermediate transfer medium is transferred to another recording medium, as in the printer 10A of the second embodiment (FIG. 5). It is suitable to first perform printing by the second recording head unit 50 for special colors and then perform printing by using the first recording head unit 30 for general colors.

FIG. 6 shows a printer 10B of the third embodiment. In the printer 10B, a distance L1 between the first recording head unit 30 and the second recording head unit 50 is set to a recording medium interval L2 (a preceding one) of a plurality of sheets of recording media sequentially conveyed by the conveyance mechanism 11. It is equal to the sheet S ₁ and the succeeding sheet S _{2 2} and the transport pitch). Since the other configuration is the same as that of the first embodiment, the same reference numerals are given to the portions common to the first embodiment, and the description will be omitted.

In the printer 10B of the third embodiment, the first recording head unit 30 and the second recording head unit 50 are moved in the main scanning direction (directions indicated by arrows B and C) in synchronization with each other. without being affected by the non-printing area that exists between the sheet S ₁ and the succeeding sheet S _2, it can be printed by the first recording head unit 30 and the second recording head unit 50. As a result, even if the first recording head unit 30 for general colors and the second recording head unit 50 for special colors are separated from each other, it is possible to avoid a decrease in printing speed. Further, it is possible to earn a drying time until the ink ejected from the first recording head unit 30 reaches the second recording head unit 50.

FIG. 7 shows a printer 10C of the fourth embodiment. In this printer 10C, the distance L3 between the first recording head unit 30 for general colors and the second recording head unit 50 for special colors is set to an integral multiple of the recording medium interval (recording medium conveyance pitch) L2. Yes. Similarly to the third embodiment (FIG. 6), the printer 10C of this embodiment also moves the first recording head unit 30 for general colors and the second recording head unit 50 for special colors in synchronization. by preceding sheet S ₁ and without being influenced by the non-printing area between the succeeding sheet S _2, the first of the second recording head unit of the recording head portion 30 and a special color for general color 50 can form an image. As a result, even if the first recording head unit 30 for general colors and the second recording head unit 50 for special colors are separated from each other, it is possible to avoid a decrease in printing speed.

As described above, the printer according to the embodiment includes the following steps.
The sheet S is moved in a predetermined conveyance direction by the conveyance mechanism 11.
The first recording head unit 30 is moved in the main scanning direction perpendicular to the sheet S conveyance direction by the first head driving mechanism 36.
An image of the general color ink is formed on the sheet S by discharging the general color ink from the first recording head unit 30 toward the sheet S.
Returning the first recording head unit 30 after image formation to the initial position.
The second recording head unit 50 is moved by the second head driving mechanism 56 in the main scanning direction orthogonal to the sheet S conveyance direction.
An image of the special color ink is formed on the sheet S by discharging the special color ink from the second recording head unit 50 toward the sheet S. And
The second recording head unit 50 after image formation is made to wait at the end position (stroke end) on the forward path side. The second recording head unit 50 may be returned to the initial position without waiting at the end position on the forward path side.

  The general color printing by the first recording head unit 30 and the special color printing by the second recording head unit 50 may be reversed. For example, in the case of “front printing”, an image is formed by the second recording head unit 50 for special colors on the image formed by the first recording head unit 30 for general colors. On the other hand, in the case of “back printing” and transfer printing, an image is formed by the first recording head unit 30 for general colors on the image formed by the second recording head unit 50 for special colors. To do. In any case, the printing by the second recording head unit 50 for special colors is performed at the beginning or the end of the color superposition sequence by the first recording head unit 30.

  The second recording head unit 50 may include a general color inkjet head in addition to the special color inkjet head 50a. In short, a general color inkjet head is mounted on the first recording head unit 30, and a special color inkjet head is mounted on the second recording head unit 50, and the first and second recording head units 30, 50 are mounted. Can be moved in the main scanning direction independently of each other along the first and second guides 35 and 55.

  The present invention can also be applied to an image forming apparatus for printing on sheets other than printing paper, for example, sheets of various forms, cloth, plastic, and the like. The embodiments of the present invention are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  S: Sheet (an example of a recording medium) 10, 10A, 10B, 10C ... Inkjet printer, 11 ... Conveying mechanism, 30 ... First recording head, 30a, 30b, 30c, 30d ... Inkjet head for general colors, 35 ... 1st guide, 36 ... 1st head drive mechanism, 50 ... 2nd recording head part, 50a ... Inkjet head for special colors, 55 ... 2nd guide, 56 ... 2nd head drive mechanism.

Claims (4)

A transport mechanism for transporting the recording medium;
An ink-jet head that discharges general-color ink, and a first recording head unit that moves in the main scanning direction along the first guide;
A first head driving mechanism for moving the first recording head unit in the main scanning direction;
An ink jet head that discharges special color ink is mounted, and is spaced apart from the first recording head portion in the recording medium conveyance direction, along the second guide parallel to the first guide. A second recording head unit that moves in the main scanning direction independently of the first recording head unit;
A second head driving mechanism for moving the second recording head unit in the main scanning direction;
A controller for controlling the first and second recording head units;
An image forming apparatus comprising:   The controller moves the first recording head unit from the initial position toward the end position on the forward path side to form an image of general color ink, and then returns the first recording head unit to the initial position. The second recording head unit is moved from the initial position toward the end position on the outward path side to form an image with special color ink, and then the second recording head section is placed on standby at the end position on the outward path side. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 1, wherein the first recording head unit is disposed upstream of the second recording head unit in a conveyance direction of the recording medium.   2. The distance between the first recording head unit and the second recording head unit is an integral multiple of a recording medium interval of a plurality of recording media conveyed by the conveyance mechanism. 4. The image forming apparatus according to any one of items 1 to 3.

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