JP6922620B2 - Light irradiation device - Google Patents

Description

The present invention relates to a light irradiation device that irradiates line-shaped light.

Conventionally, in a sheet-fed printing press, an ultraviolet curable ink that is cured by being irradiated with ultraviolet rays has been used as the ink. The sheet-fed printing press is provided with a light irradiation device that irradiates line-shaped light (hereinafter, also referred to as "line light") to cure the ultraviolet curable ink.

As a light irradiating device that irradiates line light, for example, in Patent Document 1, a plurality of light source units that emit band-shaped light are provided, and each optical axis surface of each band-shaped light emitted from them is aligned on an object to be processed. It is disclosed that the light is arranged in a radial pattern so as to intersect with each other to form a line light. In this light irradiation device, the band-shaped light emitted from each light source unit is irradiated to the object to be processed at different incident angles and superposed on the object to be processed, so that the line light is irradiated on the object to be processed. Increased strength.

However, since the light irradiation device disclosed in Patent Document 1 is installed with the light source unit itself tilted with respect to the object to be processed, the density of the line light emitted on the object to be processed is increased. There is a problem that it is difficult.

Further, in the printing machine, since the recording medium such as paper, which is the object to be processed, is conveyed at high speed, the object to be processed may flutter during the transfer. When the object to be processed flutters, the position of the object to be processed is displaced in the direction perpendicular to the plane direction in which the object to be processed extends from the predetermined transport path, that is, in the depth direction. The irradiation intensity is partially changed, and as a result, uneven curing may occur in the ultraviolet curable ink supported on the object to be treated.
Therefore, the irradiation intensity of the line light irradiating the object to be processed is positioned so as to be displaced in the depth direction from the planned irradiation area where the object to be processed is to be irradiated with the line light in a predetermined transport path. Sometimes it is preferable that they are substantially equivalent.
However, in the light irradiation device disclosed in Patent Document 1, since the range in the depth direction in which individual band-shaped lights emitted from each light source unit can be superposed is narrow, the light irradiation device is affected by the fluttering of the object to be processed. There is a problem that it is difficult to prevent the image from the ultraviolet curable ink carried on the object to be treated from causing uneven curing when the position is displaced in the depth direction.

Japanese Unexamined Patent Publication No. 2010-287547

The present invention has been made based on the above circumstances, and an object thereof is high for the object to be processed even when the position of the object to be processed is displaced from a predetermined transport path in the depth direction. An object of the present invention is to provide a light irradiation device capable of irradiating line light having a high irradiation intensity condensed with a density.

In the light irradiation device of the present invention, the sheet-shaped object to be processed is arranged along the one direction on a parallel plane facing the transport path which is conveyed in one direction along one surface of the object to be processed. A planar light source unit composed of a plurality of LED arrays each extending along a direction perpendicular to the one direction arranged, and the one direction in the vicinity of the transport path by collecting light from the light source unit. It consists of an imaging optical system that forms an image on a line extending along a vertical direction.
The imaging optical system is composed of an aggregate of lens system units, each of which has a light-collecting property.
Each of the band-shaped lights emitted from the plurality of LED arrays constituting the light source unit is focused via the imaging optical system.
Each lens system unit is arranged so that its focusing point is located on a line extending along a direction perpendicular to the one direction in the vicinity of the transport path, and an optical image of the LED array is arranged on the line. Is superposed.

In the light irradiation device of the present invention, it is preferable that the lens system unit has a collimating lens portion into which light from the LED array is incident.

In the light irradiation device of the present invention, it is preferable that the lens system unit constituting the imaging optical system is composed of a plurality of lens elements, and each lens element corresponds to each of the LED arrays.

In the light irradiation device of the present invention, an imaging optical system in which band-shaped light emitted from each of a plurality of LED arrays constituting a planar light source unit is an aggregate of lens system units, each of which has a condensing property. The light is collected on a line in the vicinity of the transport path through the light source. Therefore, since the depth of focus is large, the change in irradiation intensity due to the displacement in the depth direction from the planned irradiation area in the vicinity of the transport path is small, and the position of the object to be processed is displaced from the predetermined transport path in the depth direction. Even if there is, it is possible to irradiate the object to be treated with line light having a high irradiation intensity condensed at a high density so that the image by the ultraviolet curable ink carried on the object to be treated does not cause uneven curing. ..

It is sectional drawing which shows typically an example of the light irradiation apparatus of this invention. It is a perspective view which shows the light source part and the imaging optical system of the light irradiation apparatus of FIG.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a cross-sectional view schematically showing an example of the light irradiation device of the present invention, and FIG. 2 is a perspective view showing a light source unit and an imaging optical system of the light irradiation device of FIG.
In the light irradiation device of the present invention, the sheet-shaped object W to be processed is parallel to a transport path in which the object W to be processed is conveyed in one direction (hereinafter referred to as "x direction") along one surface of the object W to be processed. A planar light source unit composed of a plurality of LED arrays 11 extending along a direction perpendicular to the x direction (hereinafter referred to as "y direction") arranged so as to be arranged along the x direction on a flat surface. Has 10.
Between the light source unit 10 and the transport path of the object W to be processed, the light from the light source unit 10 is collected and extends along the y direction in the vicinity of the transport path, that is, a line-shaped scheduled irradiation region. The imaging optical system 20 for forming an image is arranged so as to face the light source unit 10.
This light irradiation device collects the band-shaped light emitted from each of the LED arrays 11 constituting the light source unit 10 into a planned irradiation region in the vicinity of the transport path of the object W to be processed, and is transported along the transport path. By performing a light irradiation treatment of irradiating the object W as line light, the image by the ultraviolet curable ink carried on the object W is cured and fixed on the object W to be processed.

[Light source]
The LED array 11 has a plurality of LEDs (light source elements) 13 mounted on a single substrate 12 in a row along the y direction, and is a light source element (LED) 13 constituting one LED array 11. The number is a number according to the length (width) extending in the y direction of the object W having the maximum size that can be subjected to the light irradiation treatment, and can be, for example, 400 to 600 pieces.
The arrangement pitch of the LEDs 13 in the LED array 11 is 2 to 4 mm.

The number of rows of the LED array 11 in the light source unit 10 can be, for example, 5 to 10 rows.
When the number of rows of the LED array 11 is in the above range, the line light obtained by condensing the LED array 11 has sufficient irradiation intensity.

[Imaging optical system]
The imaging optical system 20 is composed of an aggregate of lens system units 21, each of which has a light-collecting property.
Each lens system unit 21 is arranged so that its condensing points are arranged along a specific line extending along the y direction in the vicinity of the transport path and are arranged along the y direction, and each LED array is arranged on the line. The light image by the light emitted from each one LED 13 having the same level position in the x direction in 11 is superimposed.

The lens system unit 21 is composed of a plurality of lens elements 22, and each lens element 22 corresponds to each of the LED arrays 11.
Specifically, the lens element 22 of the lens system unit 21 is provided on the Frenel type lens portion 24 and the LED array 11 provided so that the working surface (light emitting surface) R thereof faces the transport path of the object W to be processed. It is composed of a collimator lens unit 23 composed of a collimator lens provided so as to face each other and optically adjust the light from the light source element 13 of the LED array 11 so as to be incident on the Frenel type lens unit 24.
Since the collimating lens unit 23 is provided in this light irradiation device, it is possible to increase the incident efficiency of the light emitted from the light source unit 10 on the Fresnel type lens unit 24.

The Fresnel-type lens portions 24 related to the adjacent lens elements 22 in one lens system unit 21 are integrally formed, and the entire Fresnel-type lens portion 24 in one lens system unit 21 has an optical working surface. (Light emitting surfaces) are arranged discontinuously, and each working surface is formed to have a size equivalent to the width of each collimating lens portion 23. Specifically, the entire Fresnel-type lens unit 24 in the lens system unit 21 has unit lenses (Fresnel-type lens units 24) having prism-shaped working surfaces having different lens angles so that their ridges are parallel to each other. It is assumed to have a saw-like cross section in which a plurality of lenses are arranged.

The imaging optical system 20 may be integrally formed or may be formed in a state of being divided into each lens system unit 21.
It is preferable that the Fresnel type lens portions 24 related to all the lens system units 21 in the imaging optical system 20 are arranged on the same plane. Further, it is preferable that the collimating lens portions 23 related to all the lens system units 21 in the imaging optical system 20 are also arranged on the same plane.

The irradiation intensity of the line light radiated from the light source unit 10 to the planned irradiation region via the imaging optical system 20 is such that the ultraviolet curable ink carried on the object W to be processed can be reliably cured. Specifically, it is set to 8 mW / cm ² or more.

The distance (work distance) d1 between the imaging optical system 20 and the planned irradiation region is, for example, 80 mm, and at this time, the desired irradiation intensity, that is, the ultraviolet curable ink can be reliably cured on the object W to be processed. The displacement width d2 of the object to be processed W capable of irradiating line light having an irradiation intensity of a magnitude is ± 10 mm in the depth direction from the planned irradiation region.

The maximum angle of incidence on the object W to be processed in the line light emitted from the light source unit 10 to the planned irradiation region via the imaging optical system 20 is preferably 40 degrees or less, for example.
Since the maximum incident angle with respect to the object W to be processed is 40 degrees or less, it is possible to secure a large allowable range of the displacement width of the object W to be processed from the predetermined transfer path in the depth direction due to the fluttering of the transfer. ..

[Processed object]
The object W to be light-irradiated in this light-irradiating device may be any as long as it can carry an ultraviolet curable ink.

The transport speed of the object W to be processed is, for example, 100 m / min.

In the above light irradiation device, line light is irradiated as follows. That is, first, the planar light source unit 10 emits band-shaped light from the LED array 11 constituting the light source unit 10. The light emitted from each light source element 13 of the LED array 11 is incident on the collimating lens unit 23 in each lens element 22 of the imaging optical system 20 corresponding to the light source element 13 to be parallel light, and the lens element is regarded as parallel light. It is incident on the Fresnel type lens 24 of 22, emitted from the working surface R thereof, and focused in a line on the planned irradiation region.
On the other hand, when the sheet-shaped object W to be processed is transported along the transport path at a predetermined transport speed in the transport direction (indicated by the white arrow in FIG. 1) and reaches the vicinity of the scheduled irradiation region, the planned irradiation region is reached. The light from the light source unit 10 focused on is irradiated as line light.
Then, when the ultraviolet curable ink supported on the object W to be processed is irradiated with line light, the ultraviolet curable ink is cured and a fixed image is formed on the object W to be processed.

In the light irradiation device as described above, the band-shaped light emitted from each of the plurality of LED arrays 11 constituting the planar light source unit 10 is composed of an aggregate of lens system units 21 each having a light-collecting property. The light is focused on a line in the vicinity of the transport path via the imaging optical system 20. Therefore, since the depth of focus is large, the change in the irradiation intensity of the line light due to the displacement in the depth direction from the planned irradiation region in the vicinity of the transport path is small, and the position of the object W to be processed is in the depth direction from the predetermined transport path. Even when displaced, line light with high irradiation intensity is focused on the object W to be processed at a high density that does not cause uneven curing in the image due to the ultraviolet curable ink carried on the object W to be processed. Can be irradiated.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made.

10 Light source unit 11 LED array 12 Substrate 13 Light source element (LED)
20 Imaging optical system 21 Lens system unit 22 Lens element 23 Collimated lens unit 24 Fresnel type lens unit R Action surface W Object to be processed

Claims (4)

Sheet-shaped objects to be processed are arranged so as to be lined up along the one direction on a parallel plane facing a transport path which is conveyed in one direction along one surface of the object to be processed, each of the above directions. A planar light source unit consisting of a plurality of LED arrays extending in a direction perpendicular to the direction, and a light source unit that collects light and extends in a direction perpendicular to the one direction in the vicinity of the transport path. It consists of an imaging optical system that forms an image on a line,
The imaging optical system is composed of an aggregate of lens system units, each of which has a light-collecting property.
Each of the band-shaped lights emitted from the plurality of LED arrays constituting the light source unit is focused via the imaging optical system.
Each lens system unit is arranged so that its focusing point is located on a line extending along a direction perpendicular to the one direction in the vicinity of the transport path, and an optical image of the LED array is arranged on the line. A light irradiation device characterized in that The light irradiation device according to claim 1, wherein the lens system unit includes a collimating lens portion into which light from the LED array is incident. The first or second aspect of the present invention, wherein the lens system unit constituting the imaging optical system is composed of a plurality of lens elements, and each lens element corresponds to each of the LED arrays. Light irradiation device. The light irradiation device according to claim 3, wherein the lens element includes a Fresnel type lens portion.

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