JP7213792B2 - Light irradiation device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light irradiation device using an LED as a light source, which is suitably used for product inspection and illumination of works of art.

In this type of light irradiation device, the chromaticity of emitted light may vary slightly due to individual differences in LEDs and long-term use.
On the other hand, when the emitted light is required to have a constant chromaticity, such as for inspection of specific products or illumination of works of art, the aforementioned variations must be suppressed.
Therefore, for example, it is simply conceivable to reduce the variation by inserting a chromaticity conversion filter in a light irradiation device having a large variation in chromaticity.

However, in reality, the variation in chromaticity is not so large. may change too much.

JP 2019-121451 A

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and it is an object of the present invention to provide a light irradiating device capable of finely adjusting the chromaticity of emitted light and easily performing the adjustment.

That is, the light irradiation device according to the present invention includes an LED, a first sheet filter and a second sheet filter that change the chromaticity of the light emitted from the LED and transmits the light, and a holder that holds the sheet filters in an overlapping manner. and
The holder is configured to be able to hold any one of the sheet filters upside down or at any one of a plurality of predetermined installation angles,
Each sheet filter is provided with a non-conversion region that transmits incident light without chromaticity conversion and a conversion region that converts the chromaticity of incident light,
It is characterized in that the degree of overlap between the non-conversion region of the first sheet filter and the non-conversion region of the second sheet filter is changed when the front and back or the installation angle of any one of the sheet filters is changed. and

In this case, by increasing the area ratio of the non-converted area in the sheet filter, the direction of the chromaticity conversion vector of the sheet filter can be shortened by the length without changing the direction. can be done. That is, it is possible to freely change the degree of chromaticity conversion by the sheet filter so as to decrease. Therefore, it is possible to solve the conventional problem that the chromaticity changes too much and cannot be adjusted.

On the other hand, when the front and back or the installation angle of any of the sheet filters is changed, the degree of overlap between the non-conversion area of the first sheet filter and the non-conversion area of the second sheet filter changes. The sheet filter changes the total chromaticity conversion vector. This means that if the sheet filters having the non-convertible areas are prepared in advance, then the holding posture of each sheet filter can be changed to either the reversed front or back side or one of a plurality of predetermined installation angles. A simple setting operation can change the total chromaticity conversion characteristics of the two sheet filters.

Therefore, by this simple operation, it is possible to reduce variations in chromaticity due to instrumental errors and aging of the light irradiation device, and set the irradiation light to have a constant chromaticity range.

In order to widen the range of chromaticity adjustment, it is preferable that the chromaticity conversion characteristics of the first sheet filter and the chromaticity conversion characteristics of the second sheet filter are different from each other. It is preferable that the direction of the chromaticity conversion vector by the first sheet filter and the direction of the chromaticity conversion vector by the second sheet filter are different from each other when represented by the chromaticity conversion vector in the chromaticity coordinates.

As a specific embodiment in which the present invention can be easily implemented, the outer contour of the sheet filter is square, and the installation angle with respect to the holder can be changed by 90°.

In order to mix and emit the light that has passed through the non-conversion region and the conversion region, for example, a light guide may be further provided, and the light emitted from the LEDs may pass through the sheet filters and the guide. It is desirable to have a structure in which the light passes through the light body and is emitted to the outside.

According to the above-described present invention, while using a sheet filter, only by increasing or decreasing the non-converted area, it is possible to solve the conventional problem that the chromaticity changes too much and cannot be adjusted, and enables delicate chromaticity adjustment. becomes. Moreover, the total chromaticity conversion characteristics of the two sheet filters can be changed by a simple operation of setting the holding posture of each sheet filter to either the above-mentioned upside down or one of a plurality of predetermined installation angles. In addition, it is possible to reduce variations in chromaticity caused by instrumental errors and aging of the light irradiation device, and to set the irradiation light to have a constant chromaticity range.

1 is a longitudinal sectional view of a light irradiation device according to one embodiment of the present invention; FIG. The disassembled perspective view of the light irradiation apparatus in the same embodiment. FIG. 4 is a perspective cross-sectional view showing the inside of the light guide and the holder in the same embodiment, which are vertically split in half. FIG. 4 is an explanatory diagram for explaining a chromaticity conversion vector of each sheet filter and a total chromaticity conversion vector (composite chromaticity conversion vector) when these sheet filters are superimposed; FIG. 10 is a simulation result showing changes in chromaticity conversion vectors when the sheet filter stacking method is changed in the same embodiment. FIG.

An embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 to 3, the light irradiation device 100 according to the present embodiment is used for inspecting a light irradiation object such as a product (hereinafter referred to as a work W), and includes a plurality of LEDs 1 , a wiring board 5 on which these LEDs 1 are mounted, and a light guide 4 for guiding the light emitted from the LEDs 1 and emitting it to the outside.

Each part will be explained.
As the LED 1, a surface-mounted type is used here. Of course, a cannonball type or a COB type may be used.

As shown in FIG. 2 and the like, the wiring board 5 has a square outer peripheral shape in a plan view, and has a square annular shape in which a square center hole 5a concentric with the outer peripheral shape is provided in the center. be. The LEDs 1 are arranged on one surface of the wiring board 5 (hereinafter also referred to as an LED mounting surface).

As shown in FIGS. 1 to 3, the light guide 4 is in the shape of a square tube made of a material that transmits light, such as acrylic or glass. More specifically, the light guide 4 has a substantially square outer peripheral shape in cross section, and a square through hole 4a concentric with the outer peripheral shape is formed in the center thereof.

One end surface of the light guide 4 is set as a light incident surface 4b. This light entrance surface 4b forms a square ring. In addition, the outer peripheral surface 4d of the light guide 4 is painted white, and the light introduced into the inside from the light entrance surface 4b is diffusely reflected there, and the inner peripheral surface of the light guide 4 It is designed to be ejected from 4c.

As shown in FIG. 1, the LED 1 mounted on the wiring board 5 is arranged so as to face the light incident surface 4b of the light guide 4, and is configured to irradiate light toward the inside thereof. . Also, for this purpose, a holder 3 for holding the wiring board 5 and the LED 1 is further provided here.

As shown in FIGS. 1 to 3, the holding body 3 is a columnar body having a square cross section integrally protruding from the inner peripheral edge of the light entrance surface 4b of the light guide body 4. An insertion hole 3a having an axis aligned with the through hole 4a is passed through.
The holder 3 has a multi-stage shape (three-stage shape in this case) in which the outer diameter becomes smaller toward the tip.

The first stepped portion 31 closest to the proximal end rises from the inner peripheral edge of the light entrance surface 4 b of the light guide, and its thickness dimension is set to be slightly larger than the thickness dimension of the LED 1 .
The next second stepped portion 32 is set to have a size that allows the center hole 5a of the wiring board 5 to be fitted therein without backlash.
The third stepped portion 33 closest to the tip has a square prism shape with a diameter smaller than that of the second stepped portion 32, as described above.

Then, as shown in FIG. 1 and the like, the center hole 5a of the wiring board 5 is fitted into the second stepped portion 32 of the holding member 3 without backlash, and the first stepped portion of the holding member 3 is fitted. The wiring board 5 is held by the holder 3 with the inner portion of the LED mounting surface in contact with the surface of the wiring board 31 .

Furthermore, in this embodiment, two sheet-like chromaticity conversion filters (first sheet filter 21 and second sheet filter 22) are arranged in an overlapping manner between the LED 1 and the light guide body light entrance surface 4b. ing.

As shown in FIG. 2 and the like, each of the sheet filters 21 and 22 has a square shape whose outer peripheral shape is substantially the same as the outer peripheral shape of the light guide 4 in a plan view. It has a square annular shape with square central holes 21c and 22c that are sized to contact the outer periphery of the first stepped portion 31. As shown in FIG.

By sequentially fitting the center holes 21c and 22c of the sheet filters 21 and 22 into the first stepped portion 31, the sheet filters 21 and 22 are overlapped and held by the first stepped portion 31 without looseness. be done.

With such a configuration, the light emitted from the LED 1 is introduced from the light incident surface 4b of the light guide 4 after passing through chromaticity conversion by the sheet filters 21 and 22, and diffusely reflected inward by the white coating. As a result, the light is emitted from the inner peripheral surface 4c of the light guide 4 as uniform diffused light.

As shown in FIG. 1, the work W is arranged slightly below the axis of the light guide 4, that is, slightly outside the other end surface of the light guide 4, and is positioned inside the light guide 4. Low-angle illumination from the surroundings is provided by diffused light emitted inward from the peripheral surface 4c.

An observation means V such as a camera is arranged above the axis of the light guide body 4, that is, outside one end surface of the light guide body 4, so that the work W illuminated at a low angle can be viewed as described above. It can be observed from above through the insertion hole 3a and the through hole 4a.

Thus, in this embodiment, as shown in FIGS. 2 and 3, color sheets 21b and 22b are provided with a plurality of (many) holes 21a and 22a as the first sheet filter 21 and the second sheet filter 22. I am using something else.

That is, these sheet filters 21 and 22 have non-conversion areas (the holes 21a and 22a) that transmit incident light without chromaticity conversion, and conversion areas (the color sheet 21b) that convert the chromaticity of incident light. , 22b) are formed alternately. The holes 21a and 22a in this embodiment are both circular and intermittently provided regularly or irregularly. 2, 4, and 5, the sizes and positions of the holes 21a and 22a are not matched for illustrative purposes.
Next, the chromaticity conversion characteristics of the sheet filters 21 and 22 having such configurations will be described.

For example, the light that has passed through the first sheet filter 21 includes the light that has passed through the holes 21a and has not been chromaticity-converted and the light that has passed through the color sheet 21b and has been chromaticity-converted. The second sheet filter 22 is also the same. In this embodiment, the light transmitted through these sheet filters 21 and 22 is mixed in the light guide 4, so the chromaticity conversion characteristic of the sheet filter 21 (or 22) It refers to the change in chromaticity of transmitted and mixed light with respect to the chromaticity of the previous light.

Based on this assumption, in this embodiment, the sheet filters 21 and 22 have different chromaticity conversion characteristics. More specifically, in terms of XY chromaticity coordinates, the chromaticity conversion characteristic is represented by a chromaticity conversion vector that moves from the chromaticity coordinates of light before transmission to the chromaticity coordinates of light after transmission. However, in this embodiment, the direction of the chromaticity conversion vector by the first sheet filter 21 and the direction of the chromaticity conversion vector by the second sheet filter 22 are at least different.

Here, the direction of the chromaticity conversion vector is determined by the materials of the color sheets 21b and 22b, while the length of the chromaticity conversion vector is determined by the area ratio of the holes 21a and 22a to the entire area. Increasing the area ratio of the holes 21a and 22a shortens the length of the chromaticity conversion vector.

By the way, as described above, since the sheet filters 21 and 22 form a square ring, they are symmetrical in the left-right direction, symmetrical in the vertical direction, and also rotationally symmetrical at every 90°. Therefore, even if each of the sheet filters 21 and 22 is changed from the original posture to any changed posture such as left-right reversal (horizontal reversal), vertical reversal (vertical reversal), 90°, 180° or 270° rotation. , can be attached to the holding body 3 without changing its shape.

That is, the first sheet filter 21 can be stacked on the second sheet filter 22 in eight relatively different orientations including the original orientation and seven modified orientations.

In short, this means that eight ways of superimposing the first sheet filter 21 and the second sheet filter 22 can be selected. By setting the position, number, size or shape of the holes 22a, the holes 21a of the first sheet filter 21 and the holes 22a of the second sheet filter 22 are arranged in at least two of the eight ways of overlapping. are changed so that the total chromaticity conversion characteristic (composite chromaticity conversion vector) of the first sheet filter 21 and the second sheet filter 22 is changed.

A simulated concrete example is shown in FIG. Here, the first sheet filter 21 and the second sheet filter 22 are superimposed in four ways: (1) superimposition as it is, (2) horizontal reversal, (3) vertical reversal, and (4) 180° rotation. We simulated how the synthetic chromaticity transformation vector changes when superimposed.

As can be seen from the graph in FIG. 5, when the composite chromaticity transformation vectors (1) to (3) are compared, their directions and orientations are unchanged, but their lengths are changed. From this, it can be seen that the degree of chromaticity conversion can be changed depending on the superimposition method. Note that (3) and (4) overlap differently but have the same degree of overlap, so the synthetic chromaticity transformation vectors are the same.

Next, a method for producing and using such sheet filters 21 and 22 will be described.
The variation range of chromaticity due to instrumental error and aging in the light irradiation device 100 can be predicted to some extent based on the specifications and actual measurements of the LED 1. Chromaticity conversion characteristics can also be obtained by calculation.

Therefore, first, two materials (color sheets 21b and 22b) having different directions of chromaticity conversion vectors are selected. Then, the color sheets 21b and 22b are perforated to form the sheet filters 21 and 22. As shown in FIG.

At this time, as described above, the direction of the original chromaticity conversion vector does not change depending on the perforation, and only the length of the chromaticity conversion vector changes depending on the area ratio of the holes 21a and 22a. The area ratio of the holes 21a and 22a is determined so that the combined chromaticity conversion vector is close to the desired chromaticity conversion characteristics.
Next, the number, positions, and sizes of the holes 21a and 22a are determined by simulation or the like so that a desired adjustment range for chromaticity conversion can be obtained depending on the superposition method.

After the sheet filters 21 and 22 are prepared in this way, for example, for the light irradiation device 100 with small chromaticity variation, a superposition method with a small chromaticity conversion vector ((1) in FIG. 5) is selected. Therefore, for the light irradiation device 100 having a large chromaticity variation, a superimposing method with a large chromaticity conversion vector ((3) or (4) in FIG. 5) is used. As a result, variations in chromaticity due to instrumental errors can be reduced. In addition, changes in chromaticity due to aging can be corrected by simply changing the way the sheet filters 21 and 22 are superimposed depending on the degree of aging.

According to the light irradiation device 100 described above, when the area ratio of the holes 21a and 22a in the sheet filters 21 and 22 increases, the length of the chromaticity conversion vector changes in the direction of shortening. Since the chromaticity conversion characteristics of the sheet filters 21 and 22, which are the basis of the sheet filters 21 and 22, can be freely adjusted so as to fall within a desired characteristic range in which the chromaticity does not change too much.

As long as such sheet filters 21 and 22 are prepared in advance, all that is left to do is to simply set the stacking method of the sheet filters 21 and 22 to one of a plurality of predetermined patterns. It is possible to reduce variations in chromaticity due to instrumental errors and aging of the light irradiation device 100 and to set the irradiation light to have a certain chromaticity range only by the work.

It should be noted that the present invention is not limited to the above embodiments.
For example, in the above-described embodiment, the non-conversion areas are formed by perforating the color sheet, but the chromaticity conversion paint is partially applied to the transparent sheet to form the conversion areas. A non-transformed portion may be set as a non-transformed region. In that case, in the above embodiment, holes, which are non-transformed areas, are scattered in the transformed area, but the opposite may be true.

It is not necessary to make the synthetic chromaticity transformation vector of each sheet filter different in all of the different superposition methods, and it is sufficient that the synthetic chromaticity transformation vector is different in at least any two different superposition methods.

The chromaticity conversion characteristics of each sheet filter may be the same or different. In particular, if the directions of the chromaticity conversion vectors are different from each other, it is possible to freely create a composite chromaticity conversion vector, which is very suitable.
The shape of the non-converted area and the converted area is not limited to a circular shape, but may be rectangular, polygonal, star-shaped, other irregular shapes, or linear.

The sheet filter may also have a square shape, a polygonal shape, or a circular shape in accordance with the type of the light emitting surface of the light irradiation device, instead of being limited to a shape with a hole in the center. However, the mode of holding by the holding body is limited to that in which the posture can be changed in stages. This is because a device that can be attached while continuously changing its posture has poor reproducibility and takes time to adjust.

Although the light guide is not always necessary, it is preferable that the chromaticity-converted light transmitted through the sheet filter and the non-chromaticity-converted light are mixed. It is preferable to provide means.
In addition, various modifications and combinations of embodiments may be made as long as the gist of the present invention is not violated.

100... Light irradiation device 1... LED
21... First sheet filter 22... Second sheet filter 3... Holding bodies 21a, 22a... Holes (non-converting regions)
21b, 22b...color sheet (conversion area)
4... light guide

Claims (5)

an LED;
a first sheet filter and a second sheet filter that change the chromaticity of the light emitted from the LED and transmit it;
a holding body for holding the sheet filters in an overlapping manner,
The holding body is configured to be able to hold any one of the sheet filters by turning them inside out or changing the installation angle of any of the sheet filters in stages ,
Each sheet filter is provided with a non-conversion region that transmits incident light without chromaticity conversion and a conversion region that converts the chromaticity of incident light,
It is characterized in that the degree of overlap between the non-conversion region of the first sheet filter and the non-conversion region of the second sheet filter is changed when the front and back or the installation angle of any one of the sheet filters is changed. and a light irradiation device. 2. The light irradiation device according to claim 1, wherein chromaticity conversion characteristics of said first sheet filter and chromaticity conversion characteristics of said second sheet filter are different from each other. When the chromaticity conversion characteristic is represented by a chromaticity conversion vector on chromaticity coordinates, the direction of the chromaticity conversion vector by the first sheet filter and the direction of the chromaticity conversion vector by the second sheet filter are different from each other. The light irradiation device according to claim 2. 4. The light irradiation device according to any one of claims 1 to 3, wherein the outer peripheral shape of said sheet filter is square, and the installation angle with respect to the holder can be changed by 90 degrees. 5. The light according to any one of claims 1 to 4, further comprising a light guide, wherein the light emitted from said LED is transmitted through each of said sheet filters and said light guide and emitted to the outside. Irradiation device.

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