1. Field of Invention
The present invention relates to a light irradiation device, and relates specifically to a light irradiation device forming a linear or planar light source being provided with a plurality of LEDs.
2. Description of Related Art
For light irradiation devices being provided with LEDs, for example in JPA-2006-235617 a UV irradiation device is described in which a plurality of LEDs is arranged side by side on a substrate. In this device, LED elements are arranged all over a large-area substrate corresponding to the maximum size of a liquid crystal panel substrate, and only the necessary LEDs are lighted and perform the irradiation for the intended curing of a sealant. Further, in JP-A-2002-303988, an exposure device is described wherein light emitting diodes are arranged on the same substrate such as mentioned above and light is irradiated towards a workpiece such as a substrate directly below the device.
In the technique described in the JP-A-2006-235617, the workpiece 103 is, for example, a liquid crystal panel substrate. In this case, a sealant is provided rectangularly along a defined picture element frame between two substrates, and liquid crystals are filled into the interior of these picture element frames. To perform the curing of the sealant sandwiched between the substrates, only the LEDs corresponding to a rectangular lighting region are supplied with power and are lighted.
But with the above-mentioned light irradiation device in which LEDs 101 are arranged side by side on a substrate, sometimes a uniform light irradiation cannot be effected because of fluctuations in the radiation among the individual LEDs 101 or fluctuations in the deterioration characteristics among the LEDs 101. Because of these conditions, with devices in which a plurality of LEDs 101 is arranged side by side on a plane such as in the device shown in
To solve this problem, a segment light source using an integrator lens such as shown in
In
Even if one LED among the plurality of LEDs 23 has become non-lighting, the uniformess of the irradiance at the irradiation surface is maintained and a specified irradiance can be provided by increasing the output of the LEDs being able to light which are provided in the segment light source 2.
With the light irradiation device of JP-A-2006-235617, by means of providing a power supply device switching ON and OFF for each LED it is possible to select and determine a lighting region according to the shape of the workpiece. Therefore, it is conceivable that it is possible to constitute a light irradiation device by arranging a plurality of segment light sources of
In JP-A-2006-235617, it is possible to select and determine an irradiation region according to the shape of a workpiece by providing a power supply device switching ON and OFF for each LED. Similarly, it is conceivable that also with the above mentioned segment light source of
That is, if segment light sources are arranged adjacent to each other, the radiation from each segment light source overlaps at its boundaries at the irradiation surface, as is shown in
The present invention was made to solve the above mentioned problems and has the object to suppress peaks of the added-up light quantities among segment light sources and to make it possible to render the distribution of the irradiance at the surface to be irradiated uniform.
To solve the above mentioned problems, in the present invention the aperture sizes of each cell lenses at that side of the integrator lens provided in each segment light source which opposes the LEDs, or the aperture sizes provided at positions corresponding to each cell lens of a mask arranged at that side of each cell lens which opposes said LEDs are made up of various kinds of sizes differing in dimensions and the irradiance distribution at the surface to be irradiated by each segment light source is rendered such that the irradiance becomes highest at the central positions and the irradiance decreases gradually from the center towards the outer edges. When such segment light sources are arranged adjacent to each other, the regions in which two segment light sources overlap become such that regions with a low irradiance overlap and peaks of added-up light quantities between segment light sources can be suppressed.
By means of the above mentioned constitution, a peak of added-up light quantities can be suppressed in a region where two segment light sources overlap, but in a region where three or more segment light sources overlap, a region where light from these three or more segment light sources overlaps is formed and the added-up light quantities are great and the uniformess of the irradiance distribution may deteriorate. Thus, corner radii or corner cuts are provided at the corner parts of each cell lens or at the corner parts of the apertures of the mask provided at that side of each cell lens that opposes the LEDs. By means of this configuration, peaks of added-up light quantities in regions in which the light of three or more segment light sources overlaps can be suppressed.
Here, the shapes (shape at the light entrance face) of all cell lenses of that side of said integrator lens which opposes the LEDs are similar, and the aperture size of each cell lens is the size (surface area or dimension of length and width etc.) of the part acting as the lens (the part becoming a spherical face) of each cell lens. If a mask is provided at that side of each cell lens which opposes the LEDs, the apertures of this mask are also similar, and, such as mentioned above, also the aperture size of this mask is the size (surface area or dimension of length and width etc.) of each aperture of the mask. If a mask is provided, the aperture sizes of all cell lenses of the integrator lens may be the same.
That is, with the present invention the above mentioned problems are solved as follows:
(1) In a light irradiation device consisting of a plurality of adjacently arranged segment light sources wherein a plurality of LEDs is arranged on a substrate, an integrator lens irradiated with the light of said plurality of LEDs and a condenser lens irradiated with the emission light from said integrator lens are provided in each said segment light source. This integrator lens consists of a plurality of cell lenses, and the aperture sizes of these cell lenses at that side of the integrator lens that opposes said LEDs are made up of various kinds of sizes differing in dimensions.
(2) In a light irradiation device consisting of a plurality of adjacently arranged segment light sources wherein a plurality of LEDs is arranged on a substrate, an integrator lens irradiated with the light of said plurality of LEDs and a condenser lens irradiated with the emission light from said integrator lens are provided in each said segment light source. This integrator lens consists of a plurality of cell lenses, and a mask in which apertures are provided at positions corresponding to each cell lens is arranged at that side of said integrator lens which opposes said LEDs. The aperture sizes of this mask are made up of various kinds of sizes differing in dimensions.
(3) In said points (1) or (2), corner radii and/or corner cuts are provided at the corner parts of the cell lenses at the side which opposes the LEDs or at the corner parts of the apertures of the mask arranged at the side which opposes said LEDs.
Thus it is preferred to arrange all apertures of all cell lenses or of the mask in the irradiation area of each LED of said segment light sources such that at least one cell lens aperture of each size or mask aperture of each size is contained.
By means of a configuration as mentioned above, the light from each LED is made incident into the cell lenses (apertures of the mask) of each size, and the entrance surface areas of the emission light from each LED to the cell lenses (apertures of the mask) of each size are configured such that there are no large differences. Even if one LED should go out, the irradiance distribution at the surface to be irradiated by each segment light source can be maintained such that it is the same as before by increasing the intensity of the emission light of the other LEDs. That is, it is possible to maintain the irradiance distribution at the surface to be irradiated by each segment light source the same before and after the going-out by making up the integrator lens such that in the integrator lens, which is constituted of cell lenses with various sizes, the individual cell lenses of each size are arranged according to a certain rule, this group is made ‘one set’ and the cell lenses of this one set are arranged regularly, as will be mentioned below, and by providing for an approximately uniform radiation of light from each LED into the cell lenses of each set.
For example, by configuring the entrance surface S1 for light emitted from a certain LED into cell lenses with an aperture size of L1 and the entrance surface S2 for light emitted from another LED into cell lenses with the aperture size of L1 such that there are no large differences, and similarly configuring the entrance surface S3 for light emitted from a certain LED into cell lenses with an aperture size of L2 and the entrance surface S3 for light emitted from another LED into cell lenses with the aperture size of L2 such that there are no large differences, and further providing the same configuration also for cell lenses with aperture sizes of L3, L4 . . . , it is possible to maintain the irradiance distribution at the surface to be irradiated by each segment light source approximately the same before and after the going-out, as was mentioned above. This means that when the ratio of the entrance surfaces for the emission light from each LED into the cell lenses with the said aperture sizes of L1, L2, L3, . . . is considered, this ratio is rendered such that it becomes approximately the same ratio for each LED.
By means of the present invention, the following results can be obtained.
(1) Because the aperture sizes of all segment lenses on that side of the integration lens provided in each segment light source which opposes the LEDs, or the aperture sizes provided at positions corresponding to each segment lens of a mask arranged at that side of each segment lens which opposes said LEDs, are made up from various kinds of sizes differing in dimensions, peaks of the added-up light quantity between segment light sources can be suppressed and it can be aimed at rendering the irradiance distribution uniformly.
(2) Because all cell lenses are arranged such that at least one cell lens of each size of the differing aperture sizes is contained within the irradiation area of each LED of the segment light source, or the apertures of the mask arranged at that side which opposes the LEDs are arranged such that at least one aperture of each of the differing sizes is contained within the irradiation area of each LED of the segment light source, and the entrance surface areas for the emission light from each LED into the cell lenses or apertures with each size are configured such that there are no large differences, even if one LED should go out the irradiance distribution at the surface to be irradiated by each segment light source can be maintained such that it is the same as before by increasing the intensity of the emission light of the other LEDs.
(3) Because corner radii and/or corner cuts are provided at the corner parts of the segment lenses at the side which opposes the LEDs or at the corner parts of the apertures of the mask arranged at that side which opposes said LEDs, peaks of added-up light quantities of regions in which the light from three or more segment light sources overlaps can be suppressed.
a) and 4(b) are schematic views showing a structural example of an integrator lens arranged at the LED side.
a) is a schematic view showing a structural example of the light exit side face of an integrator lens arranged at the LED side and
a) and 6(b) are schematic views showing the configuration of a segment light source for the case of forming the integrator lens by means of one element.
a) to 10 (d) are schematic views showing the irradiance distribution at the light irradiation surface in the case of an arrangement of the cell lenses and the LEDs as in
a) to 11 (c) are schematic views showing an example for a preferred arrangement of cell lenses and LEDs for the case of cell lenses with three kinds of sizes.
a) to 12 (c) are schematic views showing an example for a preferred arrangement of cell lenses and LEDs for the case of cell lenses with four kinds of sizes.
a) and 13(b) are schematic views showing a second embodiment of the present invention.
a) to 14(d) show a comparison example to explain the second embodiment and is a view showing the irradiance distribution if no corner radii are provided.
a) to 15 (d) are schematic views showing the irradiance distribution at the light irradiation surface for the case that corner radii are provided.
a) and 16 (b) are schematic views of a light irradiation device made up by arranging LEDs side by side on a substrate.
a) and 17(b) are schematic views showing a structural example of a segment light source using an integrator lens.
a) and (b) are schematic views showing the irradiance distribution at the light irradiation surface for the case that segment light sources of
Using
As shown in
At the support plate 8, a water cooling plate 9 is provided, on the back side of which water cooling holes 91 are formed. Further, on the back side, a power supply unit 10 connected to said lead wires is arranged. The size (d×e) of the light source unit group 3 is, for example, approximately 1130 mm×510 mm.
Using
a) is a view in which a segment light source 2 is seen from the light exit face side of a transparent lens body 27.
As shown in
The reason for the provision of a plurality of LEDs 23 with the same wavelength region is that, if one of them should have gone out, this one can be compensated by the light output from the other LEDs 23. That is, by increasing the power supply to the other LEDs 23, which are able to light, their light output can be increased and, as a result, the light output from the LED 23 having gone out can be compensated. The ‘same wavelength region’ does not mean a complete conformity of the spectral distribution; as long as light can be compensated among the LEDs 23 within one segment light source 23, fluctuations are no problem.
For the light guiding body 24 a hollow tube body for which for example a metal plate has been formed into an angular tube body is used, and the light guiding body is configured such that light emitted from the LEDs 23 does not leak out to the outside. The inner surface may be a reflecting surface or a light absorbing surface.
Each LED 23 molded in the transparent resin 22 is also molded in a transparent lens body 27, and the transparent lens body 27 has the function to radiate the light emitted from the LED 23 as parallel light towards the bottom side of the paper sheet. The light emitted from the transparent lens 27 is mixed, for example, by an integrator lens 28 (281, 282) and is emitted from the light exit surface 2821 of the integrator lens 28 (282) of the light guiding body 24. That is, in this segment light source 2 the transparent lens body 27 and the integrator lens 28 are provided with the function to mix the light from the LEDs 23 and to guide it to the light exit surface 2821. Here, light being radiated in an angle of at most 16° with regard to the central light ray of the light emitted from the light source is called parallel light.
The light emitted from the integrator lens 28 is condensed, as shown in
Here, the size of the substrate 21 on which the LEDs 23 are mounted is approximately 30 mm×30 mm, and the distance from the substrate 21 to the condenser lens 291 is for example 40 mm. Further, said transparent lens 27 has a diameter of, for example, 11 mm and the height in the direction of the optical axis is 10 mm.
This integrator lens 28 consists of a plurality of cell lenses, and the aperture sizes (sizes of the spherical parts acting as lens) of the cell lenses at the side which opposes the LEDs (at the face on the entrance side of the light) are not the same. It consists of various kinds of lenses with differing diameters. In
That is, light from the cell lenses with the three kinds of sizes S, M and L for the aperture size at the light entrance side sums up in the central region of the workpiece 5 and the irradiance is the highest. Surrounding this region, a region is formed in which light from cell lenses with the second largest size M among the aperture sizes and light from cell senses with the third largest size L among the aperture sizes adds up. Then, surrounding the region in which the light from the cell lenses with the aperture sizes M and L adds up, a region is formed which is irradiated with light from cell lenses with the size L. By means of this, an irradiance distribution is formed in which the irradiance of the radiation from the segment light source 2 becomes gradually lower from the center towards the outer edges.
In the following, the region in which light from cell lenses with said aperture size S adds up will be called S′, the region in which light from cell lenses with said aperture size M adds up will be called M′, and the region in which light from cell lenses with the aperture size L adds up will be called L′.
The case in which such segment light sources 2 are arranged adjacent to each other is shown in
If segment light sources 2 shown in
a) is a view in which the face of the light entrance side of the integrator lens 281 arranged at the side close to the LEDs is seen. Like in
b) is a sectional view (a partially enlarged view) along F-F in
The face of the light entrance side of the integrator lens 28 is constituted of a plurality of cell lenses with differing aperture sizes, and in the boundary region of each cell lens, which does not function as cell lens (the part which is not a spherical face), a convex part 28a with a planar peak is formed. The surface of the convex part is, for example, configured as a diffusion face, and light irradiating from this part becomes diffusion light. The surface of said convex part may also be a light absorbing face.
The aperture sizes of all cell lenses at the face of the light exit side of the integrator lens 28 are the same, as is shown in
The curvature of the lens surface of each cell lens S, M and L of the integrator lens 28 is, for example, R=5 mm, as is shown in
In
In
Instead of arranging a mask such as mentioned above it is also possible to provide light shading (light absorbing) regions having the same shape as the mask, as is shown in
By the way, in the present invention the cell lenses with all sizes at the light entrance side of the integrator lens 28 are arranged uniformly and not uneven on the light irradiation face and the LEDs are arranged such that the light from all LEDs radiates uniformly into the cell lenses with all sizes. Thus, in case that one LED should go out, it becomes possible as mentioned above to maintain the irradiance distribution by means of all segment light sources on the surface to be irradiated before and after this going-out by increasing the intensity of the emission light of the other LEDs.
In the following, the arrangement of the cell lenses with all sizes at the integrator lens 28 and the arrangement of the LEDs by means of which the irradiance distribution can be maintained the same before and after the going out of an LED will be explained.
In
If, in this case, one LED should go out, the irradiance distribution at the surface to be irradiated by each segment light source can be maintained the same before and after the going out by increasing the intensity of the emission light of the other LEDs. This is explained by
In
Now, the ratio of the light quantity input into the cell lenses by LED5 having become non-lighting is S:M:L=3:3:4, and if the ratio of the light quantity input into the cell lenses by the lighting LED4 is the same ratio as that of LED5 with 3:3:4, it becomes possible to compensate the irradiance of the lost LED5 with LED4 without changing the irradiance distribution of the segment light source, as is shown in
If the surface areas at which the emission light from all LEDs is input into the cell lenses with a plurality of sizes are different, the following occurs. If, for example, there are five LEDs 1 to 5 and the ratio between the surface area of the input by LED5 into the size S and the surface area of the input into the size M and the surface area of the input into the size L is 3:3:4, L:M:S becomes 7:2:1 at LED4. This shows that also the light quantities input in all cell lenses with differing sizes differ according to the above mentioned ratio. If in this case for example LED5 has become non-lighting and it is attempted to increase the power supply to LED4 and to increase its emission light quantity, even if the light quantity of LED5 is compensated the irradiance distribution at the segment light source changes because of the difference between the ratio at LED5 and the ratio at LED4.
The arrangements of the cell lenses and the LEDs which make it possible to maintain the irradiance distribution the same before and after the going out of an LED will be explained further.
To maintain the irradiance distribution at the surface to be irradiated the same before and after the going out of an LED, the following configurations are thought to be preferable.
(1) A plurality respectively of segment lenses of all sizes is irradiated by one LED or at least five or more LEDs are provided.
(2) An arrangement of all kinds of cell lenses is made one set and this one set is arranged regularly.
In the following, the above mentioned point (2) will be explained further.
a) is a view in which an integrator lens consisting of three kinds of cell lenses—large, medium and small—is seen from the light irradiation side, and the light (the circles in the drawing) from five LEDs A to E is shown laid thereon. Here, the sizes of the cell lenses are shown by differing hatchings.
The ‘one set’ in this example is, as for example shown in
If, on the other hand, ‘an arrangement of all kinds of cell lenses is made one set and this one set is arranged regularly’, as is shown in
a) is a view in which an integrator lens consisting of four kinds of cell lenses—large, medium large, medium small and small—is seen from the light irradiation side, and the light (the circles in the drawing) from five LEDs A to E is shown laid thereon. The ‘one set’ in this example is the group of
Also when the kinds of cell lenses are increased in this way, it becomes possible, similar to example 1, in case that one LED should become non-lighting, to maintain the irradiance distribution on the surface to be irradiated the same before and after the going out of the LED by compensating the light quantity of the LED having gone out by the light quantities of the other LEDs.
In the above description, the case has been explained in which the integrator lens is constituted from cell lenses with a plurality of sizes, but also if a mask is provided at the light entrance side of the integrator lens, as is shown in the above mentioned
a) is a view in which each irradiation distribution from four segment light sources SE1 to SE4 at the irradiation surface of a workpiece is seen from the side of the segment light sources. The broken lines, single dotted lines, double dotted lines and dotted lines in this drawing show the irradiation regions of light emitted from the respective segment light sources SE1 to SE4.
b) shows the irradiance distribution at the section B-B of
If a plurality of segment light sources is arranged adjacent to each other, it is necessary to arrange them adjacent to each other not only laterally, as is shown in
Thus, as shown in
b) shows the irradiance distribution at the section D-D of
Because corner radii R are provided at the peak position of each cell lens as shown in
In
In
Because it is sufficient, as was explained above, if overlaps of light from the four segment light sources such as in the central region of
Number | Date | Country | Kind |
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2009-140913 | Jun 2009 | JP | national |