JP7569485B2 - Portable Lighting Device - Google Patents

Description

The present invention relates to a portable lighting device.

A portable lighting device has been proposed that uses a mask of a specific shape to shape the light irradiation range and uses a lens array to make the illuminance of the light within the irradiation range approximately uniform (see Patent Document 1).

Patent No. 4625837

However, in the conventional portable lighting device, in order to shape the irradiation area into a specific shape, a mask is placed in the optical path and an imaging lens is used to form an image of the mask. Therefore, when irradiating a specific shape of light to an irradiation position at a different distance from the portable lighting device, it is necessary to move the position of the imaging lens.
An object of the present invention is to provide a portable lighting device that has an illumination range of a specific shape, has a substantially uniform illuminance within the illumination range, and does not require focus adjustment from close range to long range.

To solve the above problems, the present invention provides a portable lighting device that includes a light source, a collimator into which light from the light source is incident, and a fly-eye lens into which light that has passed through the collimator is incident, the fly-eye lens having a plurality of lens cells arranged two-dimensionally on the light incident side and a plurality of exit side lens cells arranged two-dimensionally opposite each of the entrance side lens cells, each lens cell being rectangular or hexagonal, and having a rectangular or hexagonal illumination shape.

It is preferable that each of the lens cells on the entrance side and exit side has a side size of 500 μm or less, and between adjacent lens cells, the distance between the lens effective portion of one lens cell and the lens effective portion of the other lens cell is 10 μm or less.

It is preferable that the gap between the lens cells arranged in one row and the lens cells arranged in the row adjacent to said row has a positional variation of 3 μm or less in a direction perpendicular to the direction in which the rows are arranged.

When the range where the illuminance is 75% or more of the maximum value is defined as the main illumination range at the position where the light emitted from the portable lighting device is irradiated, it is preferable that the width from 5% of the maximum illuminance to the main illumination range is within 20% of the width of the main illumination range.

It is preferable that the main irradiation range is rectangular, the divergence angle in the direction of one side of the rectangle is 30° to 45°, and the divergence angle in the direction of the other side is 20° to 30°.

It is preferable that the light exit side of the fly-eye lens does not include an optical component that adds an optical effect to the light shaped by the fly-eye lens.

It is preferable that the light output side of the fly-eye lens does not include an optical component for shaping or homogenizing the light. If an optical component for shaping or homogenizing the light is not included, a more compact portable lighting device can be provided.

It is preferable that the light source, the collimator, and the fly's eye lens are held in a housing, and a dust cover is disposed on the light emission side of the fly's eye lens in the housing.

The light output side of the fly-eye lens may be provided with a lens whose distance from the light source is variable, and the lens may have a zoom function that can increase the divergence angle by changing the distance between the lens and the light source. By having a zoom function, the illumination range can be changed, making it possible to provide a portable lighting device that is more suited to the purpose.

It is preferable that the illuminance changes as the zoom function is activated.

The light source is preferably a light source that generates visible light, infrared light, or ultraviolet light.

The present invention provides a portable lighting device that has a specific shape for the illumination range, has a substantially uniform illuminance within the illumination range, and does not require focus adjustment from close to long distances.

1 is a schematic diagram showing a basic optical system of a portable lighting device 1 according to a first embodiment. 3A to 3C are diagrams illustrating a fly-eye lens 4, in which (a) is a front view, (b) is a side view, and (c) is an enlarged view of a portion A in (b). 1A and 1B are enlarged photographs of a fly-eye lens 4, in which FIG. 1A shows an embodiment and FIG. 1 is a table showing the axial thickness, the radius of curvature of the lens cell 40, and the rise angle when the fly-eye lens 4 is designed using various materials having different refractive indices. FIG. 3 is an enlarged view of part B in FIG. 2( c ), in which the solid line indicates the embodiment and the dotted line indicates the comparative embodiment. 13 is a graph showing the measurement of linearity of the gap between adjacent lens cells 40. These are photographs showing the illuminance pattern of light irradiated onto a screen when the screen is placed at a distance of 2 m from the portable lighting device 1, where (a) is when the portable lighting device 1 of the embodiment is used, and (b) is when a comparative embodiment of the portable lighting device is used. 1 is a table showing the radius of curvature R, lens size, and axial thickness of the lens cells of different sizes of portable lighting devices 1. 11 is a diagram showing a simulation result of an irradiation pattern of light irradiated onto a screen 4 m away from the portable lighting device 1 of the embodiment. FIG. 10 is a graph showing the illuminance in the X direction in FIG. 9 . FIG. 4 shows a modified lens cell 40. FIG. 11 is a schematic diagram showing a basic optical system of a portable illumination device 201 according to a second embodiment. (a) shows the simulation results of the irradiation pattern in the first embodiment, and (b) to (d) show the simulation results of the irradiation pattern on the screen when the distance L between the outer surface of the fly-eye lens 4 and the inner surface of the zoom lens 210 is changed in the range of 5 to 50 mm.

First Embodiment
A portable lighting device 1 according to a first embodiment of the present invention will now be described. Fig. 1 is a schematic diagram showing a basic optical system of the portable lighting device 1 according to the first embodiment.

The portable lighting device 1 is a so-called flashlight, and is equipped with a light source 2, a collimator 3, a fly-eye lens 4, and a cover plate 5, arranged in that order along the optical axis, which are held within a housing 10. Also provided within the housing 10 is a battery storage section 6 that supplies power to the light source 2.

(Light source 2)
The light source 2 is, for example, a light source that generates visible light, infrared light, ultraviolet light, or the like, and is, for example, a solid-state light source such as a light-emitting diode, or a lamp.

(Collimator 3)
The collimator 3 is a lens or a reflector, and converts the light emitted from the light source 2 into approximately parallel light. In the embodiment, the collimator 3 is a reflector/lens having a cup-shaped mirror surface, and converts the light emitted from the light source 2 into approximately parallel light within a certain range by using reflection and focusing.

(Cover plate 5)
The cover plate 5 is made of a transparent resin, and is provided at the opening on the emission side of the housing 10 .
The cover plate 5 prevents dust and water from entering the housing, ensuring the durability and environmental resistance of the portable lighting device 1.

(Fly Eye Lens 4)
Fig. 2 is a diagram for explaining the fly-eye lens 4, where Fig. 2(a) is a front view, Fig. 2(b) is a side view, and Fig. 2(c) is an enlarged view of a portion A in Fig. 2(b). Fig. 3(a) shows an enlarged photograph of the fly-eye lens 4 of the embodiment, and Fig. 3(b) shows an enlarged photograph of a fly-eye lens 4' of a comparative embodiment.

(Configuration of Fly-Eye Lens 4)
2(c), the fly-eye lens 4 includes a plurality of lens cells 40a arranged two-dimensionally on the incident side of light from the collimator 3, and a plurality of lens cells 40b arranged two-dimensionally on the exit side facing each of the incident-side lens cells 40. The lens cells 40a and the lens cells 40b are arranged on both sides of a single plate-like member, respectively, and have the same shape. When there is no need to distinguish between them, they will be described as lens cells 40.

The fly-eye lens 4 divides the light beam by the lens cell 40a on the incident side, and guides each light beam to an irradiation area by the lens cell 40b on the exit side. The shape of the light beam in the irradiation area is rectangular corresponding to the shape of the lens cell 40.
By using the fly-eye lens 4, it is possible to disperse uneven brightness of the light source, so that a uniform illuminance distribution can be obtained on the irradiation surface.

(Material of Fly-Eye Lens 4)
FIG. 4 is a table showing the axial thickness (μm), the radius of curvature R of the lens cell 40, and the rising angle (θ°) at the edge of the lens cell 40 that becomes a protruding shape when the fly-eye lens 4 is designed using various materials with different refractive indices.
4, the shape of the lens cell 40 changes when the refractive index is different, and the lower the refractive index, the larger the rise angle θ. In the embodiment, taking into consideration the ease of mold production in glass molding, releasability during molding, and mold durability, VC82, a low-melting glass with a small rise angle θ, is used as the material for the lens cell 40 (fly's eye lens 4).

(Fly Eye Lens 4 size)
3A, the fly's eye lens 4 of the embodiment is configured by arranging a plurality of rectangular lens cells 40, for example, with an aspect ratio of 6:4, two-dimensionally in a vertical and horizontal direction. The fly's eye lens 4 of the embodiment is a small-sized so-called micro fly's eye lens, and has a substantially rectangular overall shape as shown in FIG. 2A, with each side measuring 10 mm to 30 mm, and 20 mm in the embodiment.

(Size of lens cell 40)
The size (pitch) of each lens cell 40 in the fly-eye lens 4 is preferably 500 μm or less, more preferably 400 μm or less, and in this embodiment is 330 μm × 220 μm. If the lens cell 40 has an aspect ratio of 6:4 with a width of 330 μm and a length of 220 μm, 7300 lens cells are arranged in a light beam of Φ26. The size of one side of the lens cell 40 is 1/50 to 1/100 of the size of one side of the fly-eye lens 4 in this embodiment.

(Axial thickness of fly-eye lens 4)
As shown in FIG. 2C, the distance (axial thickness) between the apex of the convex portion of the incident-side lens cell 40a and the apex of the convex portion of the exit-side lens cell 40b opposite the incident-side lens cell 40a is preferably 1000 μm or less.
In this embodiment, VC82 is used as the material, and as shown in FIG. 4, the axial thickness is 800 μm, and the lens curvature radius R is 344 μm.

(Size of fly-eye lens 4 in comparative example)
A conventional, general fly-eye lens will be described below as a comparative example.
As shown in FIG. 3B, the comparative fly-eye lens 4' is configured by two-dimensionally arranging a plurality of rectangular lens cells 40', e.g., with an aspect ratio of 6:4, in a manner similar to that of the embodiment.
However, the size of each lens cell 40' of the fly-eye lens 4' in the comparative embodiment is larger than that of the embodiment, and is, for example, 1200 μm×800 μm, with at least one side being 700 μm or more.
In the comparative embodiment, the distance (axial thickness) between the apex of the convex portion of the incident-side lens cell and the apex of the convex portion of the exit-side lens cell opposing the incident-side lens cell is about 5 mm (5,000 μm).

Lens cells 40' of this comparative form have traditionally been manufactured for use as light sources for projectors, and are used in conjunction with a diffuser or light tunnel in the optical system to improve the uniformity of light, or to form the edge of a rectangular periphery by imaging the ridge of the aperture. Therefore, the size of lens cell 40' does not need to be too small to be functionally sufficient.

(Multiple placements)
However, in a small lighting device such as the portable lighting device 1, the size of the fly-eye lens 4 is small, for example, 20 mm square. The number of fly-eye lenses that can be arranged within this 20 mm square is small, at 448 in the comparative embodiment. In contrast, 6600 cells can be arranged in the embodiment.
The number of lens cells 40 also affects the uniformity of the illuminance of the irradiated light, and the greater the number, the more favorable it is for uniformity of the illuminance.
According to the embodiment, even if the size of the fly-eye lens 4 is the same, it is possible to arrange 10 times or more lens cells 40 compared to the comparative embodiment. In addition, the size of the lens cells 40 is also small. Therefore, it is possible to realize a reduction in weight and size, uniformity in the illuminance of the irradiated light, and clarity of the edges.

(Width d 10 μm or less)
5 is an enlarged view of part B in FIG. 2(c), where the solid line indicates the embodiment and the dotted line indicates the comparative embodiment. In the embodiment, between adjacent lens cells 40 in the plane on the entrance side or exit side, the width d between the lens effective portion of one lens cell 40 and the lens effective portion of the other lens cell 40, i.e., the width d of the lens non-effective portion, is 10 μm or less.
The effective lens portion is a portion that contributes to light collection in the lens cell 40, and the non-effective lens portion is a portion on the periphery of the effective lens portion that does not contribute to light collection in the lens cell 40 and where light diverges or scatters.
For example, in the comparative embodiment, the width d' is the width d' (distance) between the inflection point P of the line formed by the outline of one lens cell 40' and the inflection point P of the line formed by the outline of the adjacent lens cell 40' in a cross section passing through the vertices of each lens cell 40' shown in FIG. 5, but in the embodiment, the presence of the inflection point P is at a level that cannot be confirmed, and the width of the portion where light is scattered is 10 μm or less.

(Effect of width d of 10 μm or less: straightness)
FIG. 6 is a graph showing the measurement of the variation (straightness) in the Y-direction position of the gap extending in the X-direction between adjacent lens cells 40 in the Y-direction, for example, when the direction in which the lens cells 40 are arranged is the XY direction as shown in FIG.
In Fig. 6, black circles represent the straightness of line C which is the gap D between lens cells 40 of the fly-eye lens 4 of the embodiment shown in Fig. 3(a), and crosses represent the straightness of line C' which is the gap between lens cells 40' of the fly-eye lens 4' of the comparative embodiment shown in Fig. 3(b). The position of the gap at the left end of Fig. 6 is set to zero on the Y coordinate, and the Y-direction position of gap D when moving approximately 1200 μm to the right in the X direction in the figure is plotted.

As shown in the graph, in the comparative example, the position of the gap D' is in the range of about -1.0 μm to +5.5 μm, that is, the fluctuation width m' of the position in the Y direction is about 6.5 μm.
In contrast, in the embodiment, the position of the gap D is in the range of about -1.0 to +0.5 μm. In other words, the fluctuation width m of the position in the Y direction is 1.5 μm. Note that in the embodiment, it is not limited to 1.5 μm, and it is sufficient if it is 3 μm or less, and more preferably if it is 2 μm or less.

Figure 7 shows photographs of the illuminance pattern of light irradiated onto a screen placed 2 m away from the portable lighting device 1, where (a) is when the portable lighting device 1 of the embodiment is used, and (b) is when a comparative portable lighting device is used.

As shown in the photograph in Figure 7, in the case of the comparative embodiment in Figure 7(b), the contours of the surroundings are blurred. However, in the case of the embodiment in Figure 7(a), the contours of the surroundings are clearer than in the comparative embodiment.

As described above, in the comparative embodiment, the contour of the illumination range is blurred compared to the embodiment. This is thought to be because the gap between adjacent lens cells 40 is wide and has low linearity, making it easy for scattered light to occur. Therefore, in this comparative embodiment, if it is desired to clarify the contour of the illumination range, an aperture or the like is provided.

(Focus free)
However, in the embodiment, the gap D between adjacent lens cells 40 is narrow and the linearity is high, so that the ridges of each lens of the fly's eye lens are clear.
Therefore, scattered light is less likely to occur, and the contour of the illumination range is clear. Therefore, there is no need to provide an aperture, and no need for a focus lens to image the contour. Therefore, it is possible to reduce the weight and cost of the portable illumination device 1.

(divergence angle)
In this embodiment, the illumination light of the portable illumination device 1 is rectangular, and the divergence angle of the illumination light is preferably 30° to 45° horizontally and 20° to 30° vertically.

The effective visual field at which humans have excellent information reception is 30° horizontally and 20° vertically. However, taking into consideration individual differences and the fact that the visual field is scanned while checking, the horizontal and vertical angles are set to 30° horizontally and 20° vertically as the base, but in this embodiment, the divergence angle design values are set wider than this, at 40° horizontally and 27° vertically.

In this embodiment, the illuminated light is a rectangular pattern of 40° horizontal and 27° vertical, so the illumination range is roughly the same as the effective field of view described above, which the human brain can process as a visual field. This makes it possible to create lighting that is effective for security work and search activities.

In the embodiment, the preferred range of the divergence angle of the irradiated light is 30° to 45° horizontally and 20° to 30° vertically, which is the preferred range when there is no movement, for example, when the object is stationary such as when detecting an abnormality in a structure.
On the other hand, if the object to be confirmed is one that is moving relative to its surroundings, a wider illumination range of 40° to 90° is preferable. The configuration in this case will be described later.

(Manufacture of Fly-Eye Lens 4)
When manufacturing the fly-eye lens 4, first, the refractive index is determined from the desired divergence angle and the material to be used. Once the refractive index is determined, the possible combinations of the radius of curvature R, lens size, and axial thickness of the fly-eye lens 4 are determined, and it becomes possible to determine the shape of the fly-eye lens 4 while maintaining a proportional relationship between them.
Then, a mold in which the gap between the lenses of the lens cell 40 is 10 μm or less is manufactured, and the fly-eye lens 4 is molded by a glass molding device.
8 is a table showing examples of the radius of curvature R, lens size, and axial thickness of the lens cell of portable lighting devices of different sizes when manufactured using the same material as the portable lighting device 1 of the embodiment. The center of the table shows the embodiment, and the top and bottom show modified forms A and B.

(Experimental Results)
Fig. 9 is a diagram showing a simulation result of the illumination range of light irradiated onto a screen 4 m away from the portable illumination device 1 of the embodiment. Fig. 10 is a graph showing the actual measurement result of the illuminance in the X direction of Fig. 9.

As shown in FIG. 9, the illumination range of light emitted from the portable lighting device 1 of the embodiment onto a screen 4 m away is 3200 mm wide and 2.1 m long, and has a substantially rectangular shape of 6×4, the same as the lens cell 40.
As shown in FIG. 10 , the light intensity of the light irradiated from the portable lighting device 1 to a screen 4 m away begins to fall at a position of about 1600 mm from the center in the X direction, which is half the 3200 m in the horizontal direction of the simulation result shown in FIG. 9 , and thus corresponds to the design value.

According to the embodiment, as shown in FIG. 10, when the maximum illuminance is 100%, and the range of approximately 70% or more is the main irradiation range P, the width X1 from approximately 5% of the maximum illuminance to the main irradiation range P is approximately 300 mm. In the embodiment, half of the width of the main irradiation range P is 1600 mm, so the width X1 from 5% of the maximum illuminance to the main irradiation range P is approximately 19% of the width of the main irradiation range P, which is within 20%.

(Effects of the embodiment)
(Effect of Small Size of Lens Cell 40)
As described above, in the portable lighting device 1 of the embodiment, the size of the lens cell 40 is 330 μm×220 μm. The smaller the size of the lens cell 40, the better the homogenization effect. Therefore, according to the embodiment, since the size of each lens cell 40 is so small, even if it is mounted on a small device such as the portable lighting device 1, the emitted light can be sufficiently homogenized.

In addition, because the size of the lens cells 40 is small, many lens cells 40 can be arranged in a limited area, and the large number of lens cells 40 also makes it possible to achieve uniform illuminance of the irradiated light.

(Improved visibility)
In this way, the portable lighting device 1 has high uniformity of illuminance within the illumination range.
When adapting to light and dark in the visual field, the so-called "adaptation" occurs, where the pupil size and light-sensing cells are switched to accommodate the change in brightness. The reaction of adapting from a dark place to a bright place is light adaptation. The reaction of adapting from a bright place to a dark place is dark adaptation. In situations where light adaptation is necessary, the field of vision is too bright to see until adaptation is complete. In situations where dark adaptation is necessary, the field of vision is too dark to see until adaptation is complete.

Whereas light adaptation allows for a quick reaction, dark adaptation takes 0.1 to 1 second to adapt to a five-fold difference in darkness. Furthermore, situations requiring a change any faster than this are uncomfortable. In other words, when there is a five-fold or greater brightness distribution within the visual field, if you try to check every corner, you will need to adapt within the visual field you want to check, which will result in an unconscious feeling of discomfort as you work. Dark adaptation is particularly slow, so adaptation to bright areas within the same visual field takes priority, and as a result, areas with low illuminance will not be seen. When considering this in situations where the act of checking is related to human life or profit and loss, such as security work or search operations, it is desirable to be able to check everything in a shorter amount of time without missing anything.

In the embodiment, the illuminance is uniform, so there is no need for the eyes to adapt. This improves the visibility of the user. In this way, by avoiding the need for dark adaptation in the visual field, it becomes possible to perform a more reliable and easier confirmation activity.
In addition, if the illuminance within the irradiation range is uniform, the illuminance in the center is not so high compared to other areas in the irradiation range, so the center does not feel too much glare. Therefore, when the light is shone on a person, it is possible to ensure that the person does not feel glare and to clearly confirm the presence of the person.

(Stress-free)
Also, if the entire visual field is the same brightness, you can see the entire range without causing an adaptation reaction, and therefore you don't feel stressed.

Furthermore, if visual work is possible after dark adaptation is complete, it is possible to reliably check what is within the field of view even in low overall illuminance.

(The gap width d is small)
In this embodiment, the width d between the lens effective portion of one lens cell 40 and the lens effective portion of the other lens cell 40, i.e., the width d of the lens non-effective portion, is 10 μm or less, which is significantly smaller than 50 μm in the comparative embodiment.

(Straightness)
3, when the direction in which the lens cells 40 are arranged is the XY direction, for example, the position of the gap D extending in the X direction between adjacent lens cells 40 in the Y direction is in the range of approximately -1.0 to +0.5 μm. That is, the fluctuation width m of the position in the Y direction is 1.5 μm. That is, the linearity of the gap D between adjacent lens cells 40 is high.

(Focus free)
In this manner, in the embodiment, the gap D between adjacent lens cells 40 is narrow and the linearity is high, so that the ridges of each lens of the fly's eye lens are clear.
Therefore, the generation of scattered light caused by the gap D of the fly-eye lens 4 is suppressed to a much smaller level than in the comparative example. This makes it possible to make the drop in illuminance at the outermost periphery of the light emitted by the portable lighting device 1 steeper.
In this way, scattered light is unlikely to occur and the contour of the illumination range is clear, so there is no need to provide an aperture or a focus lens to image the contour. This makes it possible to reduce the weight and cost of the portable illumination device 1. Furthermore, the contour of the illumination range can be clearly seen , making it possible to use the device as illumination with high energy efficiency.

By taking advantage of the steep drop in illuminance at the outermost periphery of the illumination range, it is possible to illuminate only the face and below of oncoming people, providing an anti-glare effect that does not dazzle on oncoming people while allowing them to clearly see their presence.

When used to illuminate signs or billboards, this not only improves the visibility of the illuminated object, but also contributes to reducing light pollution by reducing light leakage and improving energy efficiency, as almost no light is distributed outside the illuminated object.

Furthermore, by expanding the range of use to infrared rays, it will be possible to achieve a uniform light distribution within the field of view of an infrared camera, for example, and to obtain high-resolution images without halation even with a camera with a small dynamic range.
By expanding the scope of use to ultraviolet light, it will be possible to achieve uniform sterilization and uniform UV irradiance in exposure and bonding processes for industrial applications with a simple optical system. In particular, ultraviolet light deteriorates what is irradiated, so a clear irradiated area can prevent deterioration around the irradiated area.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these. FIG. 11 is a diagram for explaining lens cells 40 in modified form C of the embodiment, showing the arrangement of lens cells 40 in a uniform hexagonal close-packed arrangement. As shown in the figure, by arranging lens cells 40 in a hexagonal close-packed arrangement, the irradiation range can be made hexagonal.

Second Embodiment
12 is a schematic diagram showing a basic optical system of a portable illumination device 201 according to the second embodiment. The portable illumination device 201 is a small portable illumination device 201 such as a flashlight, for example, similar to the first embodiment.
The portable lighting device 201 includes, in that order in the optical axis direction, a light source 2, a collimator 3, a fly-eye lens 4, and a cover plate 5, which are held in a housing 10. Also, a battery holder 6 that supplies power to the light source 2 is provided in the housing 10.
The second embodiment differs from the first embodiment in that the portable lighting device 201 further includes a zoom lens 210 on the inner side in the optical axis direction of the cover plate 5. Other than that, the second embodiment is similar to the first embodiment, and therefore a description of the same parts as the first embodiment will be omitted.

The zoom lens 210 is, for example, a single-sided concave lens made of optical glass BK7 with a radius of curvature R = -25 mm. The zoom lens 210 can move in the optical axis direction, and the relative distance in the optical axis direction to the fly-eye lens 4 can be changed.

As described in the first embodiment, a divergence angle of the irradiated light in the range of 30° to 45° horizontally and 20° to 30° vertically is a preferable range for detecting stationary anomalies, such as detecting anomalies in a structure where there is no movement.
On the other hand, when the object to be confirmed is one that is moving relative to its surroundings, a wider illumination range is required, and the divergence angle is preferably in the range of 40° to 90°.

In the second embodiment, the zoom lens 210 can be moved in the optical axis direction, and by moving it in the optical axis direction to change the relative distance to the fly-eye lens 4, it is possible to change the divergence angle in the range of 40° to 90°.

Figures 13(b) to (d) show the simulation results of the irradiation pattern on a screen 4 meters away when the distance L between the outer surface of the fly-eye lens 4 and the inner surface of the zoom lens 210 on the center of the optical axis shown in Figure 12 is changed in the range of 5 to 50 mm.
FIG. 13A shows, for comparison, the simulation results of the irradiation pattern in the first embodiment that does not include the zoom lens 210.

When the irradiation range is set to 20% or more of the maximum light amount in the irradiation pattern, the horizontal size of the irradiation range on the screen 4 meters away is 3200 mm in the first embodiment without a zoom lens shown in Figure 13 (a). Note that 20% of the maximum light amount was set based on the 5 times light amount difference that is required for the adaptation reaction.

In the portable lighting device 201 of the second embodiment, when the distance L between the fly-eye lens 4 and the zoom lens 210 is changed to 5 mm, 20 mm, and 50 mm, the horizontal size of the illumination range is expanded to 400 mm, 5200 mm, and 7500 mm.
When converted to a viewing angle, in the case of the portable lighting device 1 without a zoom lens of the first embodiment, the divergence angle is 40°, and when the distance L in the portable lighting device 201 of the second embodiment is changed to 5 mm, 20 mm, and 50 mm, the divergence angle is expanded to 53°, 66°, and 86°, respectively.

According to the second embodiment, the divergence angle can be increased in this way, so that the light irradiation range can be expanded when the object to be confirmed is moving relative to its surroundings. Therefore, it is possible to obtain an irradiation range that suits the situation.

REFERENCE SIGNS LIST 1 Portable lighting device 2 Light source 3 Collimator 4 Fly-eye lens 40 Lens cell 40a Incident lens cell 40b Exit lens cell

Claims (11)

A light source;
a collimator into which light from the light source is incident;
a fly-eye lens into which light that has passed through the collimator is incident, the fly-eye lens comprising a plurality of lens cells that are two-dimensionally arranged on a light incident side, and a plurality of exit side lens cells that are two-dimensionally arranged opposite to each of the light incident side lens cells,
The gap between the lens cells in one row and the lens cells in the row adjacent to the row is
The variation in position in a direction perpendicular to the direction in which the rows are arranged is 3 μm or less;
A portable lighting device in which each lens cell is rectangular or hexagonal, and the illumination shape is rectangular or hexagonal. Each of the lens cells on the entrance side and the exit side has a side size of 500 μm or less, and between adjacent lens cells, the distance between the lens effective portion of one lens cell and the lens effective portion of the other lens cell is 10 μm or less.
2. The portable lighting device of claim 1. At a position where light emitted from the portable lighting device is irradiated,
When the range where the illuminance is 75% or more of the maximum value is the main irradiation range,
The width from 5% of the maximum illuminance to the main illumination range is
Within 20% of the width of the main irradiation range,
3. A portable lighting device according to claim 1 or 2 . The main illumination area is rectangular,
The divergence angle in one side direction of the rectangle is 30° to 45°,
The divergence angle in the other side direction is 20° to 30°.
4. The portable lighting device of claim 3 . The light output side of the fly-eye lens does not include an optical member that applies an optical effect to the light shaped by the fly-eye lens.
5. A portable lighting device according to any one of claims 1 to 4 . The light output side of the fly-eye lens does not include an optical member for shaping or homogenizing light.
5. A portable lighting device according to any one of claims 1 to 4 . No focus lens is provided on the light exit side of the fly-eye lens.
5. A portable lighting device according to any one of claims 1 to 4. the light source, the collimator, and the fly's eye lens are held in a housing;
A dust cover is disposed on the light emission side of the fly-eye lens in the housing.
8. A portable lighting device according to any one of claims 1 to 7. a lens, the distance of which from the light source is variable, provided on the light emission side of the fly-eye lens;
a zoom function capable of enlarging the divergence angle by changing the distance between the lens and the light source;
5. A portable lighting device according to any one of claims 1 to 4 . The illumination changes with the operation of the zoom function.
10. The portable lighting device of claim 9. The light source is a light source that generates visible light, infrared light, or ultraviolet light;
11. A portable lighting device according to any one of claims 1 to 10.

Images