CN114754301A

CN114754301A - Portable lighting device

Info

Publication number: CN114754301A
Application number: CN202111535957.2A
Authority: CN
Inventors: 成田博和; 铃木昭典
Original assignee: Ricoh Industrial Solutions Inc
Current assignee: Ricoh Industrial Solutions Inc
Priority date: 2020-12-25
Filing date: 2021-12-15
Publication date: 2022-07-15
Also published as: JP2022102292A

Abstract

The invention provides a portable lighting device, which makes an irradiation range into a specific shape, makes the illumination intensity in the irradiation range approximately uniform, and does not need focusing adjustment from a short distance to a long distance. The portable lighting device (1) of the present invention comprises a light source (2); a collimator (3) into which light from the light source (2) enters; and a fly-eye lens (4) on which light passing through the collimator (3) enters, the fly-eye lens including a plurality of lens cells (40a) arranged two-dimensionally on the light entrance side and a plurality of lens cells (40b) on the light exit side arranged two-dimensionally so as to face the respective lens cells (40a) on the light entrance side, the respective lens cells (40) being rectangular or hexagonal, and the irradiation shape being rectangular or hexagonal.

Description

Portable lighting device

Technical Field

The present invention relates to a portable lighting device.

Background

Conventionally, there has been proposed a portable lighting device in which a mask (mask) having a specific shape is used to make a light irradiation range have a specific shape, and the illuminance of light in the light irradiation range is made substantially uniform by using a lens array (see patent document 1).

< Prior Art document >

< patent document >

Patent document 1: japanese patent No. 4625837

Disclosure of Invention

< problems to be solved by the present invention >

However, in order to shape the irradiation field into a specific shape, the conventional portable illumination device uses a mask disposed on the optical path and an imaging lens for imaging the image of the mask. Therefore, when light of a specific shape is irradiated from an irradiation position having a different distance from the portable illumination device, the position of the imaging lens needs to be moved.

The present invention provides a portable lighting device which makes an irradiation range a specific shape, makes illuminance in the irradiation range substantially uniform, and does not require focus adjustment from a short distance to a long distance.

< means for solving the problems >

In order to solve the above problems, the present invention provides a portable lighting device including a light source; a collimator on which light from the light source is incident; and a fly-eye lens on which light passing through the collimator is incident, the fly-eye lens including a plurality of lens cells two-dimensionally arranged on an incident side of the light and a plurality of lens cells on an exit side two-dimensionally arranged so as to face the respective lens cells on the incident side, the respective lens cells being rectangular or hexagonal, and an irradiation shape being rectangular or hexagonal.

Preferably, one side of each of the lens units on the incident side and the emission side has a size of 500 μm or less, and a distance between the lens effective portion of one lens unit and the lens effective portion of the other lens unit between the adjacent lens units is 10 μm or less.

It is preferable that a positional deviation of a gap between the lens cells arranged in one row and the lens cells arranged in a row adjacent to the one row in a direction orthogonal to the row arrangement direction is 3 μm or less.

Preferably, when a range in which illuminance is 75% or more of a maximum value in a position irradiated with light emitted from the portable lighting device is set as the main irradiation range, the illuminance is 5% of the maximum value and the width of the main irradiation range is within 20% of the width of the main irradiation range.

Preferably, the main irradiation range is a rectangle, and the divergence angle of the rectangle in one direction is 30 ° to 45 °, and the divergence angle of the rectangle in the other direction is 20 ° to 30 °.

Preferably, the fly-eye lens does not include an optical member for optically acting on the light formed on the fly-eye lens on the light emission side.

Preferably, the fly-eye lens does not include an optical member for shaping or homogenizing light on the light emission side. Without including an optical component for shaping or homogenizing the light, a more miniaturized portable lighting device can be provided.

Preferably, the light source, the collimator, and the fly-eye lens are held in a housing, and a dust cover is disposed on a light emission side of the fly-eye lens in the housing.

The fly-eye lens may include a lens whose distance from the light source is variable on the light emission side, and may have a zoom function capable of enlarging a divergence angle by changing the distance between the lens and the light source. By having the zoom function, the irradiation range can be changed, and a portable lighting device further suitable for use can be provided.

Preferably, the illuminance changes in accordance with the operation of the zoom function.

Preferably, the light source is a light source generating visible light, infrared light or ultraviolet light.

< effects of the invention >

According to the present invention, it is possible to provide a portable lighting device that has an irradiation range of a specific shape, has substantially uniform illuminance within the irradiation range, and does not require focus adjustment from a short distance to a long distance.

Drawings

Fig. 1 is a schematic diagram showing a basic optical system of a portable lighting device 1 of the first embodiment.

Fig. 2 is a diagram illustrating the fly-eye lens 4, where (a) is a front view, (b) is a side view, and (c) is an enlarged view of a portion a of (b).

Fig. 3 is an enlarged photograph of the fly-eye lens 4, where (a) is an embodiment and (b) is a comparative embodiment.

Fig. 4 is a table showing on-axis thicknesses, radii of curvature of the lens unit 40, and rising angles in the case where the fly-eye lens 4 is designed from various materials having different refractive indices.

Fig. 5 is an enlarged view of part B in fig. 2 (c), in which the solid line represents an embodiment and the dotted line represents a comparative embodiment.

Fig. 6 is a graph in which the straightness of the gap between adjacent lens units 40 is measured.

Fig. 7 is a photograph showing an illuminance pattern of light applied to a screen when the screen is disposed at a distance of 2m from the portable lighting device 1, where (a) is a case where the portable lighting device 1 according to the embodiment is used, and (b) is a case where the portable lighting device according to the comparative method is used.

Fig. 8 is a table showing the radius of curvature R, lens size, on-axis thickness of the lens unit of the portable lighting device 1 of different sizes.

Fig. 9 is a diagram showing a simulation result of an irradiation pattern of light irradiated on a screen 4m forward from the portable illumination device 1 of the embodiment.

Fig. 10 is a graph showing the illuminance in the X direction of fig. 9.

Fig. 11 is a diagram illustrating a lens unit 40 of a modified form.

Fig. 12 is a schematic diagram showing a basic optical system of the portable lighting device 201 of the second embodiment.

Fig. 13 (a) shows simulation results of the irradiation pattern in the first embodiment, and (b) to (d) show simulation results of the irradiation pattern over the screen in the case where 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.

Description of the reference numerals

1 Portable lighting device

2 light source

3 collimator

4 fly's eye lens

40 lens unit

40a incident side lens unit

40b exit side lens unit

Detailed Description

(first embodiment)

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

The portable lighting device 1 is a so-called flashlight including, in 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. In addition, a battery housing 6 for supplying power to the light source 2 is provided in the case 10.

(light source 2)

The light source 2 is, for example, a light source generating visible light, infrared light, ultraviolet light, or the like, a solid-state light source such as a light emitting diode, a lamp, or the like.

(collimator 3)

The collimator 3 is a lens or a mirror, and converts the light emitted from the light source 2 into substantially parallel light. In the embodiment, the collimator 3 is a mirror-and-lens having a cup-shaped mirror surface, and uses reflection and condensation to make the light emitted from the light source 2 substantially parallel light in a constant range.

(cover plate 5)

The cover 5 is made of transparent resin and is provided in an opening on the light emission side of the case 10. By the cover plate 5, dust and water are prevented from entering the housing, and the durability and environmental resistance of the portable lighting device 1 are ensured.

(fly-eye lens 4)

Fig. 2 is a diagram for explaining the fly-eye lens 4, in which 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 of 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 the fly-eye lens 4' of the comparative method.

(constitution of fly-eye lens 4)

As shown in fig. 2 (c), the fly-eye lens 4 includes a plurality of lens units 40a two-dimensionally arranged on the incident side of the light from the collimator 3, and a plurality of lens units 40b two-dimensionally arranged on the emission side so as to face the respective lens units 40 on the incident side. The lens unit 40a and the lens unit 40b are disposed on both surfaces of a 1-piece plate-shaped member, and have the same shape, and when it is not necessary to describe them separately, the description will be given as the lens unit 40.

The fly eye lens 4 divides the light beams by the lens unit 40a on the incident side, and guides the respective light beams to the irradiation region by the lens unit 40b on the exit side. The shape of the light beam in the irradiation region is a rectangular shape corresponding to the shape of the lens unit 40.

By using the fly-eye lens 4, the luminance unevenness of the light source can be dispersed, and therefore, a uniform illuminance distribution can be obtained on the illumination surface.

(Material for fly-eye lens 4)

Fig. 4 is a table showing an on-axis thickness (μm), a radius of curvature R of the lens unit 40, and a rising angle (θ °) of the edge portion of the lens unit 40 having a convex shape (japanese portrait り angle) in the case where the fly-eye lens 4 is designed from various materials having different refractive indices.

As shown in fig. 4, if the refractive index is different, the shape of the lens unit 40 changes, and the lower the refractive index is, the larger the rising angle θ is. In the embodiment, VC82, which is a low melting glass having a small rising angle θ, is used as the material of the lens unit 40 (fly's eye lens 4) in consideration of easiness of mold production in glass molding, mold releasability at the time of molding, and mold durability.

(size of fly-eye lens 4)

As shown in fig. 3 (a), the fly-eye lens 4 of the embodiment is configured such that a plurality of rectangular lens cells 40 having an aspect ratio of 6:4 are arranged in a two-dimensional vertical and horizontal manner. The fly-eye lens 4 of the embodiment is a small-sized, so-called micro fly-eye lens, which has a substantially rectangular overall shape as shown in fig. 2 (a), and has a side size of 10mm to 30mm, in the embodiment 20 mm.

(size of lens unit 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 the embodiment 330 μm × 220 μm. When the lens unit 40 is set to have an aspect ratio of 6:4 of 330 μm in width and 220 μm in length, 7300 lens units are arranged in a beam of Φ 26. In the embodiment, the size of one side of the lens unit 40 is 1/50 to 1/100 of the size of one side of the fly-eye lens 4.

(on-axis thickness of fly-eye lens 4)

As shown in fig. 2 c, the distance (on-axis thickness) between the apex of the convex portion of the incident-side lens unit 40a and the apex of the convex portion of the exit-side lens unit 40b facing the incident-side lens unit 40a is preferably 1000 μm or less.

In the embodiment, VC82 was used as the material, and as shown in FIG. 4, the thickness on the axis was 800 μm, and the radius of curvature R of the lens was 344 μm.

(size of fly-eye lens 4 of comparative example)

Hereinafter, a conventional general fly-eye lens will be described as a comparative method.

As shown in fig. 3 (b), the fly-eye lens 4 'of the comparative system is configured such that a plurality of rectangular lens cells 40' having an aspect ratio of 6:4 are arranged two-dimensionally in a vertical and horizontal direction, for example, as in the embodiment.

However, the lens unit 40 'of each fly-eye lens 4' of the comparative example is larger in size than that of the embodiment, and at least one side thereof is 700 μm or more, for example, 1200 μm × 800 μm.

The distance (on-axis thickness) between the apex of the convex portion of the lens unit on the incident side and the apex of the convex portion of the lens unit on the emission side opposite to the lens unit on the incident side in the comparative example was about 5mm (5,000 μm).

The lens unit 40' of the comparative method is conventionally manufactured for use as a light source of a projector, and when used, a diffuser plate or a light guide is used in combination in an optical system to improve uniformity of light, or a ridge of an aperture is formed by imaging to form an edge of a rectangular outer periphery. Therefore, even if the size of the lens unit 40' is not particularly small, it is sufficient in function.

(with many)

However, in a small illumination device such as the portable illumination device 1, the fly eye lens 4 is small in size, for example, in a 20mm quadrangle. The number of fly-eye lenses that can be arranged in the 20mm quadrangle is 448 in the comparative method. In contrast, 6600 cells can be arranged in the embodiment.

The number of lens units 40 also affects the illuminance uniformity of the illumination light, and the more the illuminance uniformity is facilitated. According to the embodiment, even if the fly-eye lens 4 has the same size, the lens unit 40 can be arranged 10 times or more as compared with the comparative method. In addition, the size of the lens unit 40 is also small. Therefore, the light weight and the size can be reduced, and the illuminance uniformity and the edge definition of the irradiation light can be realized.

(Width d10 μm or less)

Fig. 5 is an enlarged view of part B in fig. 2 (c), in which the solid line represents an embodiment and the broken line represents a comparative embodiment. In the embodiment, between the lens units 40 adjacent in each plane on the incident side or the emission side, the width d between the lens effective portion of one lens unit 40 and the lens effective portion of the other lens unit 40, that is, the width d of the lens ineffective portion is 10 μm or less.

The lens effective portion is a portion contributing to light collection in the lens unit 40, and the lens ineffective portion is a portion which does not contribute to light collection in the lens unit 40 at the outer peripheral portion of the lens effective portion and in which light is diffused and scattered.

For example, in the comparative method, in the cross section passing through the apex of each lens cell 40 ' shown in fig. 5, the width d ' is the width d ' (distance) between the inflection point P of the line formed by the contour of one lens cell 40 ' and the inflection point P of the line formed by the contour of the adjacent lens cell 40 ', but in the embodiment, the presence of the inflection point P is not confirmed, and the width of the portion where light is scattered is 10 μm or less.

(effect of width d10 μm or less: straightness)

Fig. 6 is a graph in which, when the direction in which the lens units 40 are arranged is set to the XY direction as shown in fig. 3, for example, the deviation (linearity) of the position in the Y direction of the gap extending in the X direction between the lens unit 40 and the lens unit 40 adjacent to each other in the Y direction is measured.

In the drawing of fig. 6, black dots indicate the linearity of the line C, which is the gap D between the lens cells 40 of the fly-eye lens 4 of the embodiment shown in fig. 3 (a), and cross marks indicate the linearity of the line C, which is the gap between the lens cells 40 'of the fly-eye lens 4' of the comparative method shown in fig. 3 (b). The position of the gap at the left end of fig. 6 is set to zero in the Y coordinate, and the position of the gap D in the Y direction when the X direction is oriented to the right of about 1200 μm in the drawing is plotted.

As shown in the graph, in the comparative method, the position of the gap D' is in the range of about minus 1.0 μm to + 5.5. mu.m. That is, the amplitude m' of the position in the Y direction is about 6.5. mu.m.

In contrast, in the embodiment, the position of the gap D is in the range of approximately minus 1.0 to +0.5 μm. That is, the amplitude m at the position in the Y direction is 1.5. mu.m. In the embodiment, the thickness is not limited to 1.5 μm, but may be 3 μm or less, and more preferably 2 μm or less.

Fig. 7 is a photograph showing an illuminance pattern of light irradiated on a screen when the screen is disposed at a position 2m away from the lighting apparatus 1, where (a) is a case where the lighting apparatus 1 according to the embodiment is used, and (b) is a case where the lighting apparatus according to the comparative method is used.

As shown in the photograph of fig. 7, in the comparative method of fig. 7 (b), the surrounding contour is blurred. However, in the case of the embodiment of fig. 7 (a), the surrounding outline is clear as compared with the comparative method.

As described above, in the comparative method, the outline of the illumination range is blurred compared with the embodiment. This is considered to be because the gap between adjacent lens cells 40 is wide and low in straightness, and therefore scattered light is likely to be generated. Thus, in such a comparison system, when it is desired to clarify the outline of the illumination range, a diaphragm or the like is arranged.

(Focus-free)

However, in the embodiment, since the gap D between the adjacent lens units 40 is narrow and the straightness is high, the ridge line of each lens of the fly-eye lens is clear.

Therefore, scattered light is less likely to be generated, and the outline of the illumination range is clear. This eliminates the need for a diaphragm and a focusing lens for imaging the contour. This makes it possible to reduce the weight of the portable lighting device 1 and reduce the cost.

(divergence angle)

In the embodiment, the irradiation light of the portable lighting device 1 is rectangular, and the divergence angle of the irradiation light is preferably 30 ° to 45 ° in the horizontal direction and 20 ° to 30 ° in the vertical direction.

An effective visual field with excellent human information acceptance is horizontal 30 ° and vertical 20 °. However, considering that there is an individual difference and the field of view is confirmed while scanning, the divergence angle design value is set to 40 ° horizontally and 27 ° vertically in the embodiment based on 30 ° horizontally and 20 ° vertically, and is wider than this value.

In the embodiment, since the irradiation light has a rectangular pattern of 40 ° horizontal and 27 ° vertical as described above, the effective visual field and the irradiation range, which can be collectively handled by a human being in the brain as the visual field range, substantially coincide with each other. This enables efficient illumination in alert traffic and search activities.

Note that the horizontal 30 ° to 45 ° and vertical 20 ° to 30 °, which are preferable ranges of the divergence angle of the irradiation light in the embodiment, are preferable ranges in the case where there is no movement, for example, a stationary state such as abnormality detection of a structure.

On the other hand, when the object to be confirmed moves relative to the surroundings, a wider irradiation range, i.e., 40 ° to 90 ° is preferable. The mode for this case will be described later.

(production of fly-eye lens 4)

In the case of manufacturing the fly-eye lens 4, first, the refractive index is determined by a desired divergence angle and a material used at first. After the refractive index is determined, a desirable combination of the curvature radius R, the lens size, and the on-axis thickness of the fly-eye lens 4 is determined, and the shape of the fly-eye lens 4 can be determined while maintaining the proportional relationship.

Then, a mold having an inter-lens gap of 10 μm or less in the lens unit 40 is prepared, and the fly-eye lens 4 is molded by a glass molding apparatus.

Fig. 8 is a table showing examples of the radius of curvature R, the lens size, and the on-axis thickness of the lens unit of portable lighting devices of different sizes when manufactured from the same material as the portable lighting device 1 of the embodiment. The center of the table is the embodiment, and the top and bottom are the modification a and the modification B.

(test results)

Fig. 9 is a diagram showing a simulation result of the irradiation range of light irradiated on the screen 4m forward 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 in fig. 9.

As shown in fig. 9, the irradiation range of light irradiated on the screen 4m forward from the portable illumination device 1 of the embodiment is 3200mm in width and 2.1m in length, and has a substantially rectangular shape of 6 × 4 similar to the lens unit 40.

As shown in fig. 10, the intensity of light irradiated on a screen 4m forward from the portable lighting device 1 starts to decrease at a position about 1600mm from the center in the X direction, and a value corresponding to a design value, which is half the transverse 3200m of the simulation result shown in fig. 9, can be obtained.

According to the embodiment, as shown in fig. 10, when the range of about 70% or more when the maximum value of the illuminance is 100% is set as the main irradiation range P, the width X1 from about 5% of the maximum value of the illuminance to the main irradiation range P is about 300 mm. Since half of the width of the main irradiation range P is 1600mm in the embodiment, the width X1 from 5% where the illuminance is the maximum to the main irradiation range P is about 19% of the width of the main irradiation range P and is within 20%.

(effects of the embodiment)

(effect based on the smaller size of the lens unit 40)

As described above, in the portable lighting device 1 of the embodiment, the size of the lens unit 40 is 330 μm × 220 μm. The smaller the size of the lens unit 40, the more the homogenizing (homogenizing) effect is improved. Thus, according to the embodiment, since the size of 1 lens unit 40 is small as described above, even if the device is mounted in a small size such as the portable illumination device 1, the emitted light can be sufficiently uniformized.

Further, since the size of the lens unit 40 is small, a large number of lens units 40 can be arranged within a limited range, and the illuminance of the irradiation light can be made uniform even by a large number of lens units 40.

(visibility enhancement)

In this way, the uniformity of illuminance of the portable lighting device 1 in the irradiation range is high. Here, in order to cope with the brightness and darkness in the visual field, so-called "adaptation" is performed to cope with a change in brightness while switching the pupil size and the cells that receive light. The response from adapting to darker to brighter places is a bright adaptation. The response from a brighter site to a darker site is a dark adaptation. When the bright adaptation is required, the image is dazzled and cannot be seen until the adaptation is completed. When dark adaptation is required, the image is dark until the end of adaptation and cannot be seen in the field of view.

While light adaptation can react faster, dark adaptation takes 0.1 to 1 second to adapt to 5 times different darkness levels. And is uncomfortable in the case where demand changes more rapidly. That is, if the luminance distribution is 5 times or more in the visual field range, if the user wants to confirm each corner, the user needs to perform the adaptive reaction in the visual field to be confirmed, and thus the user may feel uncomfortable while unconsciously performing the task. In particular, since dark adaptation is slow, adaptation of a bright portion is prioritized in the same field of view, and as a result, a portion with low illuminance is not visible. Considering this situation when the confirmation behavior such as alert traffic or search activity is related to human life and profit or loss, it is desirable to perform confirmation without overlooking in a shorter time.

Since the illumination is uniform in the embodiment, there is no need to adapt the eye. This improves the visibility of the user. In this way, by avoiding the need for dark adaptation within the field of view, more reliable and easier confirmation activities can be performed.

Further, if the illuminance in the irradiation range is uniform, the illuminance at the central portion is not particularly high compared to other regions in the irradiation range, and the central portion does not feel particularly dazzling. Thus, when a person is irradiated, the presence of the person can be clearly confirmed while ensuring that the irradiated person does not feel dazzled.

(without pressure)

In addition, if all the fields of view have the same brightness, all the fields can be observed with adaptive response. Therefore, no stress is felt.

In addition, when the visual work in the state of completing the dark adaptation is possible, the appearance in the visual field can be reliably confirmed even under the low illuminance as a whole.

(the width d of the gap is small)

In the embodiment, the width d between the lens effective portion of one lens unit 40 and the lens effective portion of the other lens unit 40, that is, the width d of the lens ineffective portion is 10 μ or less, and is very small compared to 50 μm in the comparative method.

(straight traveling)

In the embodiment, as shown in fig. 3, when the direction in which the lens units 40 are arranged is set to the XY direction, for example, the position of the gap D extending in the X direction between the lens unit 40 and the lens unit 40 adjacent in the Y direction is in the range of about minus 1.0 to +0.5 μm. That is, the amplitude m at the position in the Y direction is 1.5 μm. That is, the straightness of the gap D between adjacent lens units 40 is high.

(Focus-free)

In this manner, in the embodiment, since the gap D between the adjacent lens units 40 is narrow and the straightness is high, the ridge line of each lens of the fly-eye lens is clear.

Therefore, the generation of scattered light due to the influence of the gap D of the fly-eye lens 4 is suppressed to be extremely small as compared with the comparative method. This can drastically reduce the illuminance of the outermost periphery of the irradiation light of the portable lighting device 1.

In this way, since scattered light is less likely to be generated and the outline of the illumination range is clear, it is not necessary to provide a diaphragm and a focusing lens for imaging the outline. This makes it possible to reduce the weight of the portable lighting device 1 and reduce the cost. Further, the outline of the illumination range can be visually confirmed clearly, and the illumination device can be used as illumination with high energy utilization efficiency.

The illumination intensity at the outermost periphery of the irradiation range is sharply reduced, and only the face of the facing person is irradiated downward, so that the presence of the facing person can be clearly confirmed while the facing person is not dazzled.

In addition, in the case of illumination for signs and billboards, since the visibility of an object to be irradiated is improved and light other than the object to be irradiated is substantially not present, it contributes to reduction of light damage by reduction of light leakage and improvement of energy utilization efficiency.

Further, by enlarging the use range of infrared rays, for example, the light quantity distribution in the field of view of an infrared camera is made uniform, and a high-resolution image can be obtained without causing halation even in a camera having a small dynamic range.

By expanding the range of use of ultraviolet rays, uniform sterilization, uniform UV illuminance in exposure and bonding processes in industrial applications, for example, can be achieved with a simple optical system. In particular, since the ultraviolet rays deteriorate the irradiation target, deterioration around the irradiation site in a clear irradiation target region can be prevented.

The preferred embodiments of the present invention have been described above, but the present invention is not limited thereto. Fig. 11 is a diagram for explaining the lens unit 40 of modification C of the embodiment, and is a diagram showing a case where the arrangement of the lens units 40 is set to a uniform 6-side dense arrangement shape. As shown in the figure, the irradiation range can be set to 6-sided polygon by setting the arrangement of the lens cells 40 to 6-sided dense arrangement.

(second embodiment)

Fig. 12 is a schematic diagram showing a basic optical system of the portable lighting device 201 of the second embodiment. The portable lighting device 201 is a small portable lighting device 201 such as a flashlight as in the first embodiment.

The portable lighting device 201 includes a light source 2, a collimator 3, a fly-eye lens 4, and a cover plate 5 in this order in the optical axis direction, which are held in a housing 10. In addition, a battery housing portion 6 for supplying power to the light source 2 is provided in the case 10.

The second embodiment is different from the first embodiment in that the portable lighting device 201 further includes a zoom lens 210 on the inner side of the cover 5 in the optical axis direction. Otherwise, the same portions as those of the first embodiment are not described.

As the zoom lens 210, a one-sided concave lens in which BK7 is made of optical glass and the radius of curvature R is-25 mm is used as an example. The zoom lens 210 is movable in the optical axis direction, so that the relative distance with respect to the optical axis direction of the fly-eye lens 4 can be changed.

As described in the first embodiment, the range of the divergence angle of the irradiation light of 30 ° to 45 ° horizontally and 20 ° to 30 ° vertically is a preferable range for stationary abnormality detection such as abnormality detection of a structure, which does not move.

On the other hand, when the object to be confirmed moves with respect to the surroundings, a wider irradiation range is required, and a range of the divergence angle of 40 ° to 90 ° is preferable.

In the second embodiment, the zoom lens 210 is movable in the optical axis direction, and the relative distance from the fly-eye lens 4 is changed by moving in the optical axis direction, so that the divergence angle can be changed in the range of 40 ° to 90 °.

Fig. 13 (b) to (d) show simulation results of the irradiation pattern over the screen 4 meters ahead with the distance L between the outer surface of the fly-eye lens 4 above the optical axis center shown in fig. 12 and the inner surface of the zoom lens 210 being changed in the range of 5 to 50 mm.

Note that (a) of fig. 13 shows, as a comparison, a simulation result of the irradiation pattern in the first embodiment not including the zoom lens 210.

In the case where a range of 20% or more of the maximum light amount in the irradiation mode is set as the irradiation range, the lateral size of the irradiation range over the screen 4 meters ahead is 3200mm in the case of the first embodiment without the zoom lens shown in (a) of fig. 13. Note that 20% of the maximum light amount is set by a difference of 5 times the light amount required for the reaction.

In the portable illumination device 201 of the second embodiment, when the distance L between the fly eye lens 4 and the zoom lens 210 is changed to 5mm, 20mm, or 50mm, the lateral size of the irradiation range is enlarged to 400mm, 5200mm, or 7500 mm.

When converted to the viewing angle, the divergence angle is 40 ° in the case of the portable illumination device 1 without the zoom lens of the first embodiment, and the divergence angles are expanded to 53 °, 66 °, and 86 °, respectively, when the distance L is changed to 5mm, 20mm, and 50mm in the portable illumination device 201 of the second embodiment.

According to the second embodiment, since the divergence angle can be enlarged in this manner, the irradiation range of light can be enlarged when the object to be confirmed moves relative to the surroundings. This makes it possible to obtain an irradiation range suitable for the situation.

Claims

1. A portable lighting device, comprising:

a light source;

a collimator for receiving the light from the light source; and

a fly-eye lens on which light passing through the collimator enters, the fly-eye lens including a plurality of lens units two-dimensionally arranged on an entrance side of the light and a plurality of lens units on an exit side two-dimensionally arranged to face the respective lens units on the entrance side,

each lens cell is rectangular or hexagonal, and the illumination shape is rectangular or hexagonal.

2. The portable lighting device of claim 1,

one side of each of the lens units on the incident side and the emission side has a dimension of 500 μm or less, and the distance between the lens effective portion of one lens unit and the lens effective portion of the other lens unit between the adjacent lens units is 10 μm or less.

3. The portable lighting device of claim 1 or 2,

the positional deviation of the gaps between the lens units arranged in one row and the lens units arranged in a row adjacent to the one row in the direction orthogonal to the row arrangement direction is 3 [ mu ] m or less.

4. The portable lighting device of any one of claims 1-3,

when a range in which illuminance is 75% or more of a maximum value is set as a main irradiation range in a position irradiated with light emitted from the portable lighting device, the illuminance is 5% of the maximum value to within 20% of the width of the main irradiation range.

5. The portable lighting device of claim 4,

the main irradiation range is a rectangle, and the divergence angle of the rectangle in one side direction is 30-45 degrees, and the divergence angle of the rectangle in the other side direction is 20-30 degrees.

6. The portable lighting device of any one of claims 1-5,

the fly-eye lens does not include an optical member for optically acting on the light formed on the fly-eye lens on the light emission side.

7. The portable lighting device of any one of claims 1-5,

the fly-eye lens does not include an optical member for shaping or homogenizing light on the light exit side.

8. The portable lighting device of any one of claims 1 to 7,

the light source, the collimator, and the fly-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.

9. The portable lighting device of any one of claims 1-5,

a lens whose distance from the light source is variable is provided on the light exit side of the fly-eye lens,

the zoom lens has a zoom function capable of enlarging a divergence angle by changing a distance between the lens and the light source.

10. The portable lighting device of claim 9,

the illuminance changes with the operation of the zoom function described above.

11. The portable lighting device of any one of claims 1-10,

the light source is a light source generating visible light, infrared light or ultraviolet light.