JP2016068525A - Uv radiation device and drive method of uv radiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To radiate a UV efficiently to an object with a small number of UV-LED elements 1, at low cost.SOLUTION: An UV-LED unit 43 comprises plural UV-LED elements 1 which are arranged with predetermined intervals L along a second direction and have effective radiation range diameter r, radiates the UV to a medium M which is transported at transport speed V in a first direction being orthogonal to the second direction, and reciprocates the unit along the second direction at predetermined movement speed v. A control part controls at least one of the transport speed V and movement speed v so as to satisfy a conditional expression L≤r(1+v/V), therefore there is no blank area to which radiation does not reach, in the UV radiated to a surface of the medium with a zigzag-locus to the first direction, thereby the whole surface irradiated with the UV.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a UV irradiation apparatus that irradiates ultraviolet rays (hereinafter referred to as UV or UV light) and a driving method of the UV irradiation apparatus. The UV irradiation apparatus and the driving method thereof of the present invention can be applied to an image forming apparatus that forms an image with UV curable ink that is cured by UV irradiation, and even a light source including a relatively small number of light emitting elements, By appropriately driving this, the UV curable ink can be reliably cured by efficiently irradiating UV onto the print medium (media) on which the image is formed with the UV curable ink.

  As exemplified in Patent Documents 1 and 2 below, an image forming apparatus that performs image formation using a UV curable ink that is cured by ultraviolet rays is known. In such an image forming apparatus using a UV curable ink, an LED element that generates UV as a UV light source (hereinafter referred to as a UV-LED element) is used to irradiate the image of the UV curable ink formed on the medium with UV. Is provided.

  Since this UV-LED element has high directivity and an effective irradiation area is narrow, in order to uniformly irradiate UV onto a print area by UV ink formed on a medium, the UV-LED elements are arranged in several rows. It has generally been thought that it is necessary to arrange them side by side at high density. FIG. 11 is a schematic diagram showing an example of a UV irradiation apparatus based on such a conventional concept, and shows an arrangement example of the UV-LED elements 1.

  In FIG. 11, the medium is transported along a transport direction (sub-scanning direction) parallel to the vertical direction in the figure. The UV irradiation apparatus has a longitudinal direction in the width direction (main scanning direction) of the medium that is orthogonal to the transport direction, that is, in the horizontal direction in the figure, and irradiates UV on the printing surface of the transported medium. ing. That is, this UV irradiation apparatus has three element rows composed of a plurality of UV-LED elements 1 arranged at predetermined intervals along the main scanning direction, and these element rows are arranged in the sub-scanning direction. The UV-LED elements in each column are arranged in a staggered manner by arranging the UV-LED elements in the main scanning direction by shifting the positions of the UV-LED elements between adjacent columns. Further, the range in the main scanning direction in which the UV-LED elements are arranged is set longer than the width of the medium and covers the entire printing surface. In the above configuration, in order to irradiate the entire surface of the printed medium with UV, the medium is transported along the transport direction, and each UV-LED element of the UV irradiation device is turned on to irradiate the print surface of the medium with UV. To do.

  However, in order to cover the problems of UV-LED elements that have high directivity and a narrow effective irradiation area, if a configuration in which UV-LED elements are arranged in high density and in multiple rows as described above, the manufacturing cost increases. As a result, there is a problem that it becomes expensive, heavy, and power consumption increases.

  Further, in the case of adopting a configuration in which the UV-LED elements are arranged in high density and in multiple rows, if the effective irradiation area of the UV-LED elements is not properly considered, as shown in FIG. Excessive irradiation intensity due to overlapping irradiation ranges (“Irradiation overlapped and strong intensity area” in the figure) and insufficient irradiation intensity outside the irradiation range (“Irradiation does not reach and intensity is low” in the figure) May occur. In addition, since light interference occurs in a microscopic region, the intensity of irradiation is increased.

  Therefore, in order to prevent a region not irradiated with UV as shown in FIG. 12 from occurring, it may be possible to arrange the UV-LED elements at a higher density as shown in FIG. In that case, however, there is no area that is not irradiated with UV, but there are areas where the irradiation is double and strong, areas where the irradiation is triple and very strong, and areas where the irradiation is quadruple and very strong. This causes another problem that multi-stage unevenness occurs in the UV irradiation state.

As means for solving the problem of multi-stage irradiation unevenness due to the high-density arrangement of UV-LED elements having a high directivity and a narrow effective irradiation area, they are disclosed in Patent Documents 3 to 6 below. It is conceivable to use such technology.
That is, Patent Document 3 discloses a technique for scattering UV light with a UV scattering plate. Patent Document 4 discloses a technique for reducing the directivity component in the line width direction with a uniform distribution by transmitting UV light from a plurality of UV-LED elements arranged in a line to a transparent light guide. Disclosure. Patent Document 5 discloses a technique for performing uniform UV irradiation by arranging the UV-LED elements in a polygonal shape without gaps. Patent Document 6 discloses a technique for transmitting light from a light source through a Fresnel lens, although the content is not limited to a UV-LED element.

JP 2011-5785 A JP 2013-176969 A JP 2011-171366 A JP 2001-229722 A JP 2005-254560 A Japanese Patent Laid-Open No. 10-39376

  As described above, in order to uniformly irradiate UV printed images of UV ink formed on a medium in an image forming apparatus or the like, UV-LED elements are arranged in rows and arranged at high density. If it is adopted, the problem that the manufacturing cost increases and becomes expensive, the weight increases, and the power consumption increases. In addition, when such a high-density arrangement is adopted, if the effective irradiation area of the UV-LED element is not properly taken into account, the irradiation intensity is insufficient due to an insufficient irradiation intensity outside the irradiation range or excessive irradiation intensity. There is also a possibility that the problem of uneven irradiation that irradiation cannot be performed may occur. Furthermore, in order to solve the problem of uneven irradiation when UV-LED elements are arranged at high density, a light guide or a Fresnel lens is used as a means for uniformizing UV light emitted from a plurality of UV-LED elements, or Although it is conceivable to use a technology that arranges UV-LED elements in a special cross-sectional shape without gaps, this causes extra costs and increases in manufacturing costs due to the high-density arrangement of UV-LED elements in the first place. However, the problems of weight increase and power consumption are not solved.

  The present invention has been made in view of such conventional technology and its problems, and in order to uniformly irradiate the object with UV, the number of UV-LED elements is not simply increased but arranged at high density. Using as few UV-LED elements as possible, and using special parts such as the light guide for uniformization, and with no extra cost, it is as efficient as possible for the object. The objective is to enable UV irradiation without unevenness.

The UV irradiation apparatus according to claim 1 is:
A UV irradiation apparatus that irradiates a medium on which an image of UV ink is formed and conveyed at a predetermined conveyance speed along a first direction,
A light emitting unit having a plurality of light emitting elements arranged at predetermined intervals along a second direction intersecting the first direction;
A driving unit for reciprocatingly moving the light emitting unit along the second direction at a predetermined moving speed v;
When the lighting of the light emitting element is controlled, the radius of the effective irradiation range of the light emitted from the light emitting element to the medium is r, and the interval between the adjacent light emitting elements is L, the conditional expression L ≦ r (1 + v / A control unit that controls at least one of the transport speed V and the moving speed v so that V) is established;
It is characterized by comprising.

The UV irradiation apparatus according to claim 2 is the UV irradiation apparatus according to claim 1,
The length of the effective irradiation range of the light emitting unit with respect to the second direction is W1, the length of the medium with respect to the second direction is W2, and the light emitting unit reciprocates along the second direction in one direction. When the moving distance is a, conditional expression W2 ≧ a + W1 is established.

The driving method of the UV irradiation apparatus according to claim 3 is:
A plurality of light emitting elements arranged at predetermined intervals along a second direction intersecting the first direction with respect to a medium on which an image of UV ink is formed and conveyed at a predetermined conveyance speed along the first direction. In a driving method of a UV irradiation apparatus that emits ultraviolet light by emitting light from the light emitting element while reciprocating a light emitting unit having
When the radius of the effective irradiation range of the light emitted from the light emitting element to the medium is r, the interval between adjacent light emitting elements is L, the transport speed of the medium is V, and the moving speed of the light emitting element is v, It is characterized in that at least one of the transport speed V and the moving speed v is controlled so that the conditional expression L ≦ r (1 + v / V) is satisfied.

  According to the UV irradiation apparatus described in claim 1 and the driving method of the UV irradiation apparatus described in claim 3, an image of the UV ink is formed, and the medium transported at the transport speed V in the first direction. The light emitting unit that has turned on the light emitting element irradiates UV while reciprocating in the second direction at the moving speed v. At that time, the control unit has a conditional expression L ≦ r (1 + v / V) (where r is the radius of the effective irradiation range of the light emitted from the light emitting element to the medium, and L is the interval between adjacent light emitting elements). At least one of the conveyance speed V of the medium and the moving speed v of the light emitting unit is controlled so as to be established. Thereby, UV irradiated from each of the plurality of light emitting elements arranged along the second direction forms a zigzag irradiation locus on the surface of the medium with respect to the first direction. There is no gap, and a blank area that does not reach the irradiation within the UV irradiation range does not occur on the surface of the medium, and the entire surface is irradiated with UV.

  For example, when the UV irradiation apparatus is provided as an UV curing ink curing unit in an image forming apparatus that forms an image with UV curing ink, the control unit of the UV irradiation apparatus is a medium transport unit on the image forming apparatus side. Alternatively, the medium transport speed V is controlled by controlling the medium transport section provided as a configuration of the UV irradiation apparatus, or the moving speed at which the light emitting section reciprocates in the second direction by controlling the drive section of the UV irradiation apparatus. UV is irradiated so that the conditional expression is satisfied by controlling v or both the transport speed V and the moving speed v. Since a blank area that cannot be irradiated does not occur within the UV irradiation range of the medium, the UV curable ink within the same range is reliably cured by receiving the UV irradiation.

  According to the UV irradiation apparatus of the second aspect, when performing the control satisfying the conditional expression, another conditional expression W2 ≧ a + W1 (the length of the effective irradiation range of the light emitting unit in the second direction is W1, The length of the medium in the second direction is W2, and the movement distance in one direction when the light emitting unit reciprocates along the second direction is a). To do. Thus, even if the medium conveyed along the first direction is irradiated with UV while reciprocating the light emitting unit in the second direction, the UV irradiated from each light emitting element of the light emitting unit is The dimension in two directions, that is, the entire width of the medium can be covered, and the entire surface of the medium can be irradiated with UV.

1 is a schematic cross-sectional view seen from a side surface showing a schematic configuration of an image forming apparatus according to an embodiment. It is a side view of the UV irradiation apparatus provided in the image forming apparatus of the embodiment. It is a front view of the UV irradiation apparatus provided in the image forming apparatus of the embodiment. It is a bottom view of the UV irradiation apparatus provided in the image forming apparatus of the embodiment. It is a figure which shows the effective irradiation area of UV-LED (single unit) provided in the UV irradiation apparatus of the image forming apparatus of the embodiment. 1 is a functional block diagram of an image forming apparatus according to an embodiment. FIG. 3 is a plan view illustrating a relationship between media (medium), a UV irradiation device, a light emitting unit, and movement directions of the media (medium) in the image forming apparatus of the embodiment. In the image forming apparatus according to the embodiment, the length W1 of the medium (medium) in the second direction (main scanning direction), the length W2 of the light emitting unit of the UV irradiation apparatus, and the light emitting unit in the second direction (main scanning direction). It is a top view which shows the protrusion length a with respect to a medium, and shows the aspect of the continuous operation | movement of a medium and a light emission part with several fractional drawing. FIG. 4 is a diagram illustrating dimensions of each part of a UV irradiation locus formed on a medium in order to examine conditions for aligning the UV irradiation locus formed on the medium without a gap in the image forming apparatus of the embodiment. . It is a figure which shows the locus | trajectory of UV irradiation formed on the medium in the image forming apparatus of embodiment. It is a schematic diagram which shows an example of the UV irradiation apparatus which arranged the UV-LED element at high density in 3 rows in a staggered manner. It is a figure which shows the example which the blank area | region of UV irradiation produced in the UV irradiation pattern by UV irradiation apparatus like FIG. 11 which has arrange | positioned UV-LED element at high density. 11 shows another example in which the UV-LED elements are arranged at a higher density so that the blank area of the UV irradiation is not generated in the UV irradiation pattern by the UV irradiation apparatus as shown in FIG. 11 in which the UV-LED elements are arranged at a high density. FIG.

An embodiment of the present invention will be described with reference to FIGS.
In this embodiment, an arbitrary image can be formed on a medium with UV curable ink, and an image can be fixed by irradiating UV with a UV irradiation device in the apparatus to cure the UV curable ink. It relates to the device. Here, the medium means a medium to be printed with UV curable ink regardless of the material and form, and specifically includes printing paper, resin sheet, and the like. When UV curable ink is used, the image can be dried quickly by irradiating UV after image formation, and there is no limitation on the type of media that can be applied. The effect of being suitable for film printing for product packaging or labeling is obtained.

1. Overall configuration of image forming apparatus (FIG. 1)
As shown in FIG. 1, a conveyance path 4 for guiding the medium M is set in the housing 3 of the image forming apparatus 2. The transport path 4 includes a horizontal lower path 5 for forming an image on the medium M that is a recording medium, and a horizontal path for inverting the medium M formed on the surface and returning it to the lower path 5 again. It has a closed loop circuit 8 composed of an upper path 6, and two connection paths 7 that connect the both ends of the lower path 5 and the upper path 6. The medium M is formed with an image while being conveyed in the counterclockwise direction in the drawing in the circulation path 8.

  As shown in FIG. 1, a paper feeding unit 9 that supplies the medium M is connected to the upstream side of the lower path 5 of the transport path 4, and the medium M placed on a vertically movable paper feeding table is connected. From the inside, the uppermost medium M can be sent into the lower path 5. A belt conveyance mechanism 10 serving as a conveyance unit is disposed below the central portion of the lower path 5 of the conveyance path 4. The belt conveyance mechanism 10 includes a belt 11 in which a large number of holes (not shown) are formed and driven to circulate, and a suction that sucks air downward from the holes of the belt 11 that moves upward to attract the medium M to the upper surface of the belt 11. Means 12, and can convey the medium M along the lower path 5 while being attracted to the upper surface of the belt 11.

  Conveying rollers 20 serving as media M conveying means are arranged at predetermined intervals in both ends of the lower path 5 corresponding to the upstream side and the downstream side of the belt conveying mechanism 10, the upper path 6, and the two connection paths 7 and 7. The medium M can be transported along these paths 5, 6, and 7. The conveying roller 20 is arranged along the circulation path 8 as described above, and is also arranged in a paper discharge path 14 and a switchback path 15 provided to be branched to the circulation path 8 as will be described later. Yes.

  Above the belt conveyance mechanism 10 in the lower path 5, four inkjets that discharge four color inks of K (black), C (cyan), M (magenta), and Y (yellow) as image forming means. Heads 30 (hereinafter abbreviated as IJ heads 30) are juxtaposed along the conveyance direction of the medium M. These IJ heads 30 can eject ink onto the upper surface of the medium M sent by the belt conveyance mechanism 10 to form a desired color image. In this embodiment, the ink ejected by each IJ head 30 is a UV curable ink of each color.

  On the downstream side of the upper path 6 of the circulation path 8, a paper discharge path 14 provided with a conveyance roller 20 branches obliquely upward, and the end thereof is a first paper discharge tray provided in the housing 3. 16 is continuous. If the medium M on which the image is formed on the upper surface by the IJ head 30 is sent out of the circulation path 8 as it is, the medium M can be discharged onto the first paper discharge tray 16 with the upper surface facing down (face down). it can.

  On the downstream side of the lower path 5 of the circulation path 8, a discharge path 17 provided with the conveyance roller 20 branches in the horizontal direction, and a second discharge tray 18 is provided beyond the discharge path 17. . If the medium M on which the image is formed on the upper surface by the IJ head 30 is sent out of the circulation path 8 from the discharge path 17 as it is, the medium M is placed on the second discharge tray 18 with the upper surface facing up (face up). Can be discharged.

  In the circulation path 8, in the middle of one connection path 7 connecting the downstream side of the upper path 6 and the upstream side of the lower path 5, a switchback is provided slightly downstream of the branch point of the paper discharge path 14 described above. A path 15 is branched and provided. The switchback path 15 has a dead end structure, and although not shown in detail, a conveyance roller 20 is provided in the middle of the path. According to this structure, the printed medium M guided from the circulation path 8 to the switchback path 15 is reciprocated by the switchback path 15 and returned to the circulation path 8, so that the front and back of the media M in the circulation path 8 can be seen. Can be reversed. Therefore, according to this structure, it is possible to print on both sides of one medium M by a series of continuous operations. That is, while the medium M is conveyed along the lower path 5 of the circulation path 8, an image is formed on one surface by the IJ head 30, and then the medium M is sent from the upper path 6 to the switchback path 15, Is reversed and sent again from the switchback path 15 to the circulation path 8 to be turned upside down, conveyed again along the lower path 5 and passed near the IJ head 30 to form an image on the other surface. Can do.

  As described above, according to the image forming apparatus 2 of the present embodiment, the medium M is sent from the paper supply unit 9 to the lower path 5 of the circulation path 8 and conveyed, and the image is formed on the surface of the medium M by the IJ head 30. And discharged to the first paper discharge tray 16, the paper can be discharged with the image forming surface down. This is single-sided printing in which an image is formed only on one side of the medium M. Further, the medium M on which the image is formed on one side is not discharged from the first discharge tray 16, and the medium M is guided to the switchback path 15 and reciprocated in the switchback path 15 so that the front and back of the medium M are reversed. If the image is formed on the back surface of the medium M by the IJ head 30 while being transported along the circulation path 8 again, the double-sided printing can be performed. If it is discharged onto the first paper discharge tray 16, it can be discharged with the front surface printed on top. If it is discharged onto the second paper discharge tray 18 after the back side image is formed, it will be printed later. It can be discharged with the back side facing up.

2. Configuration of UV irradiation apparatus (FIGS. 2 to 6)
The image forming apparatus 2 includes a UV irradiation device 40 downstream of the belt conveyance mechanism 10 in the lower path 5. The UV irradiation device 40 has a function of irradiating the UV ink image formed on the medium M by the IJ head 30 disposed upstream thereof, and fixing the image as an image.

  As shown in FIGS. 1 to 4, according to the UV irradiation device 40, two horizontal guide shafts 41 orthogonal to the conveying direction of the lower path 5 are provided above the lower path 5. . Two bearings 42 are slidably attached to the guide shaft 41 at a predetermined interval, and UV-- serving as a light emitting unit for irradiating UV light is provided on each lower surface side of the two bearings 42. An LED unit 43 is attached. The UV-LED unit 43 is a box whose longitudinal direction is the axial direction of the guide shaft 41. On the lower surface side of the UV-LED unit 43, a plurality of UV-LED elements 1, which are light emitting elements, are arranged in a line at predetermined intervals along the axial direction of the guide shaft 41. According to the above structure, the UV-LED unit 43 can move in any direction left and right along the alignment direction of the UV-LED elements 1 orthogonal to the transport direction of the medium M.

  Here, the conveyance direction of the medium M in the lower path 5 is referred to as a first direction for convenience, and is parallel to the direction in a horizontal plane orthogonal to the medium M, that is, the axial direction of the guide shaft 41 in which the UV-LED elements 1 are arranged. This direction is referred to as the second direction. According to the image forming apparatus 2, the IJ head 30 ejects necessary ink at each position in the second direction to form an image at each position in the first direction of the medium M conveyed in the first direction. To do. In this way, in the scanning of the IJ head that ejects ink to the required position on the printing surface of the medium M, the direction corresponding to the width direction of the medium M is referred to as the main scanning direction, which is the second direction. A direction corresponding to the conveyance direction orthogonal to the width direction is referred to as a sub-scanning direction, and this is the first direction.

  FIG. 5 is a diagram illustrating an example of an effective irradiation area of the UV-LED element 1 mounted on the UV-LED unit 43. In this figure, a semicircle is drawn on the side irradiated with UV with the front end portion of the UV-LED element 1 as the center, and the length of the semicircle in the radial direction is defined as an irradiation distance (mm). The angle measured in both the left and right directions, with the line drawn forward from the tip as the reference line, is expressed as the irradiation angle (°). In the coordinate system of irradiation distance and irradiation angle shown in this figure, 0.5 mm and 1 mm are shown as the irradiation distance (mm), and the irradiation angle (°) is the horizontal direction from the reference line. The angle up to 90 ° at 15 ° intervals is shown as a guide.

  In FIG. 5, the hatched range shown superimposed on the coordinate system of the irradiation distance and the irradiation angle is the effective irradiation area of the UV-LED element 1. According to this UV-LED element 1, if it is a UV curable ink that can reach an energy of a predetermined value or more within this effective irradiation area and is cured with an energy less than this value, this UV-LED element 1 can be cured to an appropriate state within this effective irradiation area. According to this example, the effective irradiation area is represented by a closed curve, starts to spread forward from the tip of the UV-LED element 1, starts to converge from a position where the irradiation distance is about 0.7 mm, and the irradiation distance is about 1 mm. The position is the tip. Therefore, in order to irradiate the medium with UV having the most effective energy, the distance between the medium and the UV-LED element 1 is set to about 0.7 mm, and the irradiation distance is set to about 0.7 mm. Good.

  As described above, FIG. 5 is an example of the effective irradiation area of the UV-LED element 1, and the state of the effective irradiation area changes if the performance of the UV-LED element 1 and the target UV curable ink are different. Of course. Although this drawing is drawn in a plane, the actual effective irradiation area is a three-dimensional shape obtained by rotating the semicircle indicating the irradiation distance and irradiation angle coordinate system 360 ° around the reference line. It is.

  Although not shown in FIGS. 2 to 4, as shown in FIG. 6, the UV-LED unit 43 of the UV irradiation device 40 is a UV-as a driving unit provided in the mechanism unit 50 of the image forming apparatus 2. The LED unit driving unit 51 is configured to reciprocate and move along the guide shaft 41. The UV-LED unit driving unit 51 may be any means that can move the UV-LED unit 43 back and forth along the guide shaft 41 with a necessary stroke regardless of the principle or mechanism. The motor and other actuators and a known driving force transmission mechanism can be used. The UV-LED unit driving unit 51 is controlled by a mechanism control unit 52 as a control unit provided in the mechanism unit 50 of the image forming apparatus 2. The mechanism control unit 52 is controlled by a main control unit 58 as a control unit and an image formation control unit 53 as a control unit which will be described later.

  Although not shown in FIGS. 2 to 4, as shown in FIG. 6, the UV-LED element 1 of the UV-LED unit 43 includes a power control unit 54 provided in an image formation control unit 53 as a control unit. ON / OFF is controlled by.

3. Control system of image forming apparatus 2 (FIG. 6)
As shown in FIG. 6, the image forming apparatus 2 forms an image on a medium M with an operation unit 55 that sends a control signal to each unit according to a user's instruction, and UV curable ink, and irradiates the image with UV. An image forming unit 56 for curing and fixing, a mechanism unit 50 for driving the image forming unit 56, and an image forming control unit 53 as a control unit for processing image data during printing and controlling each unit. .

  As shown in FIG. 6, the operation unit 55 includes a touch panel type operation panel 57 as an input unit for a user to input an instruction and a display unit for displaying necessary information. In addition, the operation unit 55 is provided with a main control unit 58 that is a control unit that generates and outputs a control signal for comprehensively controlling each unit described later in accordance with an instruction input from the operation panel 57.

  As shown in FIG. 6, the image forming unit 56 includes the IJ head 30 and the UV-LED unit 43 described above.

  As shown in FIG. 6, the mechanism unit 50 moves the IJ drive unit 59 that drives the IJ head 30 of the image forming unit 56 and the UV-LED unit 43 described above in the second direction (the first direction in which the medium is conveyed). A UV-LED unit driving unit 51 is provided that moves back and forth along the orthogonal direction of the medium. The IJ driving unit 59 and the UV-LED unit driving unit 51 of the mechanism unit 50 are controlled by mechanism control units 60 and 52 as control units provided respectively. Each of these mechanism control units 60 and 52 is controlled by control of the main control unit 58 based on image data supplied from an image formation control unit 53 as a control unit described later.

  As shown in FIG. 6, the image formation control unit 53 is provided with an image memory unit 61 which is a frame memory for storing image data to be printed in a bitmap format for each frame. As a supply source for supplying data to the image memory unit 61, an I / F input processing unit 62 to which image data is input from an external personal computer (PC) or the like is provided. The image data input from the I / F input processing unit 62 is stored in the image memory unit 61 through a raster image processing (RIP) 63. When the image data input from the I / F input processing unit 62 is data in the bitmap format, it is stored in the image memory unit 61 as it is, but when it is command data, raster image processing (RIP) 63 is stored. Thus, it is converted into a bitmap image and stored in the image memory unit 61. The bitmap format image data stored in the image memory unit 61 is converted into output image data by the output image processing unit 64 and is given to the IJ head 30 of the image forming unit 56 to drive it. Further, the image formation control unit 53 is provided with a power supply control unit 54 that controls lighting and non-lighting of the UV-LED unit 43 of the image forming unit 56 described above. The image forming control unit 53 also detects the state of each part of the apparatus (for example, the size of the paper to be used, the presence / absence of media in the paper feeding unit 9, etc.) based on the detection signal input from a sensor or the like disposed in each part of the apparatus. A memory 65 is provided for grasping and holding the data as data, and this data is used for image formation on a medium.

4). Regarding the arrangement and movement control of the UV-LED element 1 (FIGS. 7 to 10)
In the image forming apparatus 2 described above, the UV-LED unit 43 performs the process of fixing the image by irradiating the medium M on which the image M is formed with the UV ink by the IJ head 30 while irradiating the medium M. Control and the like will be described.

  As described above, the UV-LED elements 1 of the UV-LED unit 43 of the present embodiment are arranged in a line at a predetermined interval along the second direction. Therefore, the medium is simply moved in the first direction without causing the UV-LED unit 43 to move in the second direction while emitting each UV-LED element 1 with the necessary luminance and irradiating the medium with UV. Then, in the case where the effective irradiation range on the medium M of the UV-LED element 1 is set not to overlap, a range in which the surface of the medium M is not irradiated with UV occurs in a stripe shape along the first direction. If the interval between the UV-LED elements 1 is narrowed so that the effective irradiation ranges of the adjacent UV-LED elements 1 overlap on the medium M, such a problem does not occur. The elements 1 are densely arranged, and the problems described in [Background Art] and [Problems to be Solved by the Invention] cannot be solved.

  In the present embodiment, in order to solve such a problem, the UV-LED elements 1 are arranged in a line as described above, and the distance between the UV-LED elements 1 is also set so that the effective irradiation ranges on the medium M do not overlap. The number of UV-LED elements 1 to be used is reduced as much as possible. Under such conditions, the UV-LED unit 43 and the like are controlled as described below in order to irradiate the entire UV within the predetermined range on the medium M or the entire surface of the medium M. To do.

  As shown in FIG. 7, the medium M on which an image is formed with UV ink by the IJ head 30 is transported at the transport speed V along the first direction. On the other hand, UV is irradiated to the medium M while moving the UV-LED unit 43 above the medium M back and forth along the second direction at a moving speed v.

  FIG. 8 continuously shows the operation of moving the UV-LED unit 43 reciprocally along the second direction (left and right direction in the drawing) with respect to the medium M. Here, the length (width) of the medium M in the second direction is W1, and the length of the effective irradiation range of the UV-LED unit 43 in the second direction (generally, two pieces at both ends of the second direction). This corresponds to the interval between the UV-LED elements 1). In FIG. 8, the width of the UV-LED unit 43 as an apparatus is displayed as W2, but this is for convenience of illustration, and in short, the emission width of the UV-LED unit 43 is W2. It means that.

  As shown in FIG. 8A, the central position in the second direction of the medium M conveyed along the first direction (vertical direction in the figure) and the central position in the second direction of the UV-LED unit 43 are as follows. The position of the UV-LED unit 43 that matches is referred to as an initial position (home position) of the UV-LED unit 43.

  As shown in FIGS. 8A and 8B, when the medium M is sent at the transport speed V along the first direction with the UV-LED unit 43 in the initial position, the UV-LED element 1 The UV-LED unit 43 that has been lit starts moving at a moving speed v in the second direction, for example, in the right direction.

  As shown in FIG. 8 (3), the right end of the effective irradiation range of the UV-LED unit 43 protrudes outward from the right outer edge of the medium M by a length a, and the left end of the effective irradiation range of the UV-LED unit 43 is the medium M. When the UV-LED unit 43 comes into contact with the left outer edge, the movement of the UV-LED unit 43 stops to the right, and the direction is quickly changed to the left as shown in FIGS. 8 (4) and (5). And move at speed v.

  As shown in FIG. 8 (6), the left end of the effective irradiation range of the UV-LED unit 43 protrudes outward from the left outer edge of the medium M by the length a, and the right end of the effective irradiation range of the UV-LED unit 43 is the medium M. When the UV-LED unit 43 comes into contact with the right outer edge, the UV-LED unit 43 stops moving in the right direction and quickly changes its direction to the left. Thereafter, the surface of the medium M is irradiated with UV while repeating the same operation and reciprocating left and right.

As described above, the UV-LED unit 43 whose effective irradiation range is W2 is reciprocated in the second direction with respect to the medium M having the width W1 conveyed in the first direction, and the dimensions are respectively measured at both ends of the medium M. When operated so as to protrude outward by a, it is necessary to satisfy the following formula as a condition for covering the entire surface of the medium M within the effective irradiation range of the UV-LED unit 43.
W2 ≧ a + W1 Conditional expression (1)

  In the example of the irradiation mode shown with reference to FIG. 8, the entire surface of the medium M is irradiated with UV. However, depending on the image forming conditions, the UV curable ink is not necessarily applied to the entire surface of the medium M. Is not limited. For example, in the case where an image non-formation region (margin) is provided at both edges in the width direction (second direction) of the medium M, the conditional expression (1) is obtained assuming a substantial width of the image formation region. It only has to be satisfied.

  As described above with reference to FIG. 7 and FIG. 8, while transporting the medium M in the first direction, the UV-LED unit 43 that is driven to emit light is reciprocated along the second direction. When an operation of projecting the dimension a at both edges in the second direction is performed, each effective irradiation range of each UV-LED element 1 on the surface of the medium M draws a zigzag pattern along the first direction. FIG. 9 shows this in a simplified manner.

  In FIG. 9, r is the radius of the effective irradiation range E of the UV-LED element 1, and L is the distance between the adjacent UV-LED element 1 and the UV-LED element 1 in the second direction in the UV-LED unit 43. Is the angle when the pattern of the effective irradiation range of the UV-LED element 1 drawn on the medium M is zigzag-folded, and x is the pattern of the effective irradiation range of each UV-LED element 1 It is the dimension of the 2nd direction in the corner | angular part turned back zigzag-shaped. Here, θ is an amount depending on the transport speed V of the medium M in the first direction and the moving speed v of the UV-LED unit 43 in the second direction, and tan θ = V / v.

As shown in FIG. 9, when two adjacent UV-LED elements 1 each draw a pattern of an effective irradiation range on the medium M, the effective irradiation ranges do not overlap as shown by the hatched lines in the figure depending on conditions. An unirradiated region S is generated. The condition for preventing such an unirradiated region S from occurring is expressed by the following equation (A), as can be seen from the relationship between the dimensions indicated by the symbols in the figure.
L ≦ r + x Formula (A)

Here, as can be seen from FIG. 9, since x = r / tan θ and tan θ = V / v as described above, x = r × (v / V). Substituting this formula into formula (A) and rearranging gives the following conditional formula (2).
L ≦ r (1 + v / V) Conditional expression (2)

  If conditional expression (2) is satisfied, when UV is irradiated to the medium M transported in the first direction while the UV-LED unit 43 is reciprocated in the second direction, an unirradiated region is within the irradiation range. S does not occur.

  Since the dimensions L and r of the UV-LED unit 43 provided in the image forming apparatus 2 are usually fixed values and cannot be easily changed, in order to satisfy the conditional expression (2), the medium M is conveyed. At least one of the speed V and the moving speed v of the UV-LED unit 43 may be set as appropriate under the control of the main control unit 58, the image formation control unit 53, and the like by designation from the operation panel of the operation unit. In general, the conveyance speed V of the medium M is determined according to the resolution of the image to be formed. For example, when the resolution is 600 dpi, the conveyance speed is 600 mm / sec, and when the resolution is 300 dpi, the conveyance speed is 300 mm / sec. Two to three types of transport speeds can be selected such as sec. Accordingly, an appropriate conveyance speed is selected from such options in consideration of the necessary resolution, and the movement speed v of the UV-LED unit 43 that satisfies the conditional expression (2) is selected and set. Good.

  In addition, by changing the transport speed V of the medium M and the moving speed v of the UV-LED unit 43 and replacing the UV-LED unit 43 provided in the image forming apparatus 2, the dimension L and the dimension r are changed. It is also possible to satisfy the conditional expression (2). Conditional expression (2) is set by appropriately setting at least one of the transport speed V of the medium M and the moving speed v of the UV-LED unit 43 and at least one of the dimension L and the dimension r of the UV-LED unit 43. It is also possible to satisfy.

  FIG. 10 is a diagram illustrating a locus of UV irradiation formed on the medium M in the image forming apparatus 2 of the embodiment. As described above, the effective irradiation ranges of the respective UV-LED elements 1 moving in a zigzag manner on the medium M overlap each other, and no unirradiated region S is generated.

  As described above, the UV-LED unit 43 reciprocates left and right at the speed v along the second direction, so that the UV-LED unit 43 actually stops to change direction at both ends of the moving range. When doing and starting to move, the motion is a positive or negative acceleration motion and not a consistent constant velocity motion. Therefore, strictly speaking, the effective irradiation range of the UV-LED element 1 does not draw a sharply bent pattern on the medium M as shown in FIG. However, since such positive or negative acceleration acts for a very short time with respect to the entire movement, there is virtually no problem even if it is handled as a constant velocity motion.

  In the embodiment described above, the UV-LED elements 1 of the UV-LED unit 43 are arranged in a line along the second direction, but the lines of the UV-LED elements 1 parallel to the second direction are A plurality of rows may be arranged at predetermined intervals in the first direction so that the positions of the respective UV-LED elements 1 in the second direction are the same.

5. Effects of the Embodiment According to the UV irradiation device 40 of the image forming apparatus 2 and the driving method thereof described above, the UV-image is formed on the medium M on which a UV ink image is formed and transported at the transport speed V in the first direction. The UV-LED unit 43 with the LED element 1 lit irradiates UV while reciprocating in the second direction at a moving speed v. At this time, the conveyance speed of the medium M and the size and speed of each part of the UV-LED unit 43 are The setting and the like are determined so that the conditional expression (1), that is, L ≦ r (1 + v / V) is satisfied. Therefore, the UV irradiated to the medium M from each UV-LED element 1 is zigzag with respect to the first direction and forms an irradiation locus without a gap on the medium M. A blank area that does not reach irradiation does not occur in the inside, and UV is irradiated on the entire surface of a necessary range.

  Further, when the control satisfying the conditional expression (1) is performed, if the driving of the UV-LED unit 43 is controlled so that another conditional expression (2), that is, W2 ≧ a + W1, is satisfied, the width direction is necessary. The region can be irradiated with UV, and the entire surface of the medium M can be irradiated.

  As described above, according to the UV irradiation apparatus 40 and the driving method thereof according to this embodiment, the present invention can be applied to the image forming apparatus 2 that forms an image with the UV curable ink that is cured by the irradiation of the UV. -Even if it is a low-cost light source unit in which the LED elements 1 are arranged at a low density, the UV to be irradiated can be efficiently reached on the medium M without any gap by properly driving the light source unit, thereby ensuring UV curable ink. The effect that it can be hardened is obtained.

DESCRIPTION OF SYMBOLS 1 ... UV-LED element as a light emitting element 2 ... Image forming apparatus 30 ... Inkjet head (IJ head)
DESCRIPTION OF SYMBOLS 40 ... UV irradiation apparatus 43 ... UV-LED unit 51 as a light emission part 51 ... UV-LED unit drive part as a drive part 52 ... Mechanism control part 53 as a control part 53 ... Image formation control part 58 as a control part 58 ... Control part As the main control unit M ... media (medium)
V ... Media transport speed v ... UV-LED unit moving speed

Claims (3)

A UV irradiation device that irradiates ultraviolet rays onto a medium on which an image of UV ink is formed and conveyed at a conveyance speed V along a first direction,
A light emitting unit having a plurality of light emitting elements arranged at predetermined intervals along a second direction intersecting the first direction;
A driving unit for reciprocatingly moving the light emitting unit along the second direction at a predetermined moving speed v;
When the lighting of the light emitting element is controlled, the radius of the effective irradiation range of the light emitted from the light emitting element to the medium is r, and the interval between the adjacent light emitting elements is L, the conditional expression L ≦ r (1 + v / A control unit that controls at least one of the transport speed V and the moving speed v so that V) is established;
UV irradiation apparatus characterized by comprising. The length of the effective irradiation range of the light emitting unit with respect to the second direction is W1, the length of the medium with respect to the second direction is W2, and the light emitting unit reciprocates along the second direction in one direction. The UV irradiation apparatus according to claim 1, wherein conditional expression W2 ≧ a + W1 is established, where a is a movement distance. A plurality of light emitting elements arranged at predetermined intervals along a second direction intersecting the first direction with respect to a medium on which an image of UV ink is formed and conveyed at a predetermined conveyance speed along the first direction. In a driving method of a UV irradiation apparatus that emits ultraviolet light by emitting light from the light emitting element while reciprocating a light emitting unit having
When the radius of the effective irradiation range of the light emitted from the light emitting element to the medium is r, the interval between adjacent light emitting elements is L, the transport speed of the medium is V, and the moving speed of the light emitting element is v, A driving method of a UV irradiation apparatus, wherein at least one of the transport speed V and the moving speed v is controlled so that a conditional expression L ≦ r (1 + v / V) is satisfied.