CN114543007A

CN114543007A - Lighting device

Info

Publication number: CN114543007A
Application number: CN202111317960.7A
Authority: CN
Inventors: 成田博和
Original assignee: Ricoh Industrial Solutions Inc
Current assignee: Ricoh Industrial Solutions Inc
Priority date: 2020-11-10
Filing date: 2021-11-09
Publication date: 2022-05-27
Also published as: JP2022076885A

Abstract

The invention provides a lighting device which can clearly distinguish an irradiation region and a non-irradiation region to uniformly irradiate, and is light and small. The 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 that has passed through the collimator (3) enters, the fly-eye lens including a plurality of lens units (40a) that are two-dimensionally arranged on the light entrance side and a plurality of lens units (40b) that are two-dimensionally arranged on the light exit side so as to face the respective lens units on the light entrance side, one side of each of the lens units (40) on the light entrance side and the light exit side being 500 [ mu ] m or less in size, and the distance between the lens effective portion of one lens unit (40) and the lens effective portion of the other lens unit (40) between adjacent lens units (40) being 10 [ mu ] m or less.

Description

Lighting device

Technical Field

The present invention relates to a lighting device.

Background

Conventionally, an illumination device has been disclosed (see patent document 1) which includes a light source, a collimator optical system for making a parallel light beam, an integrator optical system for making a light intensity distribution of the light beam uniform, an aperture (aperture), and an optical system having a positive power.

The illumination device is an illumination device capable of illuminating an illumination region corresponding to the shape of an illuminated surface such as a relatively large rectangular shape such as a poster, a billboard, a painting, or a board. In the illumination device, the integrator optical system has a fly-eye lens and a condenser lens. The divergent light flux from the light source is collimated by the collimator optical system, enters the fly-eye lens, and passes through each fly-eye lens to become an independent small-diameter light flux. These small-diameter light fluxes are superposed on each other by a condenser lens, and combined at the position of the aperture of the diaphragm into a light flux having uniform light intensity. According to the above illumination device, the illumination region and the non-illumination region can be distinguished from each other and can be uniformly illuminated.

< Prior Art document >

< patent document >

Patent document 1: japanese laid-open patent publication No. 2018-006250

Disclosure of Invention

< problems to be solved by the present invention >

However, in recent years, there has been a demand for a lighting device that can illuminate an illuminated region and a non-illuminated region uniformly while being more clearly distinguished, and that is further lightweight and compact.

< means for solving the problems >

In order to solve the above problem, the present invention provides an illumination 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 so as to face the respective lens units on the entrance side, a dimension of one side of each of the lens units on the entrance side and the exit side being 500 μm or less, and a distance between a lens effective portion of one lens unit and a lens effective portion of another lens unit between adjacent lens units being 10 μm or less.

Preferably, a positional deviation of a gap between the lens unit arranged in one row and the lens unit arranged in a row adjacent to the one row in a direction orthogonal to the row arrangement direction is 3 μm or less.

The arrangement pitch of the lens units may be non-uniform.

Preferably, a dimension of one side of the lens unit is 1/50 to 1/100 of a dimension of one side of the fly-eye lens.

The light source may be a light source generating visible light.

The light source may be a light source generating infrared light.

The light source may be a light source generating ultraviolet light.

< effects of the invention >

According to the present invention, it is possible to provide a light-weighted and compact illumination device that can illuminate an illumination region and a non-illumination region uniformly while clearly distinguishing them from each other.

Drawings

Fig. 1 is a schematic diagram showing a basic optical system of the illumination device 1.

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

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

Fig. 4 is an enlarged view of a portion B of fig. 2 (c), in which a solid line represents an embodiment and a broken line represents a comparative embodiment.

Fig. 5 is a graph for measuring the positional deviation (linearity) of the gap between adjacent lens units 40.

Fig. 6 (a) is a photograph showing the illuminance pattern of light applied to the screen in the case where the illumination device 1 of the embodiment is used, and (b) is a photograph showing the illuminance pattern of light applied to the screen in the case where the illumination device of the comparative method is used.

Fig. 7 is a graph in which the luminance at the center in the longitudinal direction of the photograph in the illuminance mode of fig. 6 is expressed in 256 gradations, and a thick line is an embodiment and a thin line is a comparative embodiment.

Fig. 8 is a diagram for explaining a first modification of the embodiment, where (a) is a diagram showing a case where the shape and the arrangement pitch of the lens cells 40 are rectangular and uniform, and (b) and (c) are diagrams showing a first modification in which the shape and the arrangement pitch of the lens cells 40 are randomly rearranged by ± 10%.

Fig. 9 is a graph showing the respective luminances in the XY directions of the light emitted from the illumination device 1, where fig. 9 (a) is the case of fig. 8 (a), and fig. 9 (b) is the case of fig. 8 (b).

Fig. 10 is a diagram for explaining a second modification of the embodiment, where (a) is a diagram showing a case where the arrangement of the lens cells 40 is set to a uniform hexagonal dense arrangement shape, and (b) is a diagram showing the second modification in which ± 10% of the shape of the lens cells 40 is randomly rearranged.

Fig. 11 is a graph showing the respective luminances in the XY directions of the light emitted from the illumination device 1, where fig. 11 (a) is the case of fig. 10 (a), and fig. 11 (b) is the case of fig. 10 (b).

Description of the reference numerals

1 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

The lighting device 1 according to the embodiment of the present invention will be described below. Fig. 1 is a schematic diagram showing a basic optical system of the illumination device 1. The lighting device 1 is a small lighting device 1 such as a flashlight. However, the lighting device 1 of the present invention is not limited to a flashlight, and may be another lighting device. The illumination device 1 includes a light source 2, a collimator 3, and a fly-eye lens 4. The overall divergence angle of the illumination device 1 of the embodiment is 40 ° in the horizontal direction and 27 ° in the vertical direction.

(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.

(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).

As shown in fig. 2 (c), the fly-eye lens 4 includes a plurality of lens units 40a two-dimensionally arrayed on the incident side of the light from the collimator 3, and a plurality of lens units 40b two-dimensionally arrayed 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 have the same shape, and the lens unit 40 will be described as the lens unit 40 unless otherwise described.

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. By using the fly-eye lens 4, the luminance unevenness of the light source can be dispersed, and the same illuminance distribution can be obtained on the irradiation surface. The shape of the light beam in the irradiation region is a rectangular shape corresponding to the shape of the lens unit 40.

The fly-eye lens 4 is made of, for example, K-VC82 of low melting point glass. In the embodiment, the fly-eye lens 4 is molded by a glass molding apparatus by forming a mold having an inter-lens gap of a concave lens of 10 μm or less.

(size of fly-eye lens 4)

As shown in fig. 2 (a), the fly-eye lens 4 of the embodiment has a substantially rectangular shape as a whole, and has a side size of 10mm to 30mm, and 20mm in the embodiment.

Hereinafter, a conventional general fly-eye lens 4 will be described as a comparative method.

One side of the fly-eye lens 4 of the comparative example was also about 20 mm. However, the cell size of the comparative system is 1.2mm × 0.7mm, whereas the fly-eye lens 4 of the embodiment is smaller than the comparative system by 0.3mm × 0.2 mm. Therefore, when the cells are arranged in a 20mm square, 448 cells can be arranged in the comparative method, and 6600 cells can be arranged in the embodiment. In this way, since the cells can be arranged in the same size by a factor of 10 or more, the fly-eye lens 4 of the embodiment can achieve sufficient illuminance equalization even when used in a small-sized lighting device 1 such as a flashlight. In this case, the cell size can be 1/15 to 1/30 for the comparison method with respect to the size of one side, and 1/50 to 1/100 for the embodiment with respect to the size of one side.

Conventionally, although a product such as the fly-eye lens 4 of the comparative system is manufactured for use as a light source of a projector, the light uniformity is improved by using a diffuser plate and an optical channel in combination in an optical system, or the edge of the rectangular outer periphery is formed by imaging the ridge line of the aperture. Therefore, even if the cell size of the fly-eye lens 4 is not particularly small, it is sufficient in function. In contrast, in the illumination device 1 of the embodiment, the fly-eye lens 4 having a small cell size is applied, and the illuminance of the irradiation light is made uniform and the edge is made sharp. Thus, the lighting device can realize desired optical performance in a light weight and small size.

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. The fly-eye lens 4 of the embodiment and the fly-eye lens 4 'of the comparative example are configured such that a plurality of rectangular lens cells 40, 40' having an aspect ratio of 6:4 are arranged two-dimensionally in an aspect.

(size of lens unit 40)

The size of each lens cell 40 of the fly-eye lens 4 of the embodiment is 500 μm or less on one side, preferably 400 μm or less, and in the embodiment 300 μm × 200 μm. The size of one side of the lens unit 40 is 1/50-1/100 of the size of one side of the fly-eye lens 4.

On the other hand, in the fly-eye lens 4 'of the comparative system, at least one side of the size of each lens unit 40' is 700mm or more, for example, 1200 μm × 800 μm.

In this way, since the size of each lens unit 40 is 500 μm or less in the embodiment, it is possible to mount a large number of lens units 40 even if the size of the entire fly eye lens 4 is set to be small for use in a compact illumination device 1 such as a flashlight.

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, and in the embodiment 800 μm. The curvature radius R of the lens was 344 μm.

On the other hand, the distance 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 method was about 5mm (5,000 μm).

Fig. 4 is an enlarged view of a portion B of fig. 2 (c), in which a solid line indicates an embodiment and a broken line indicates 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. 4, 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.

(straight traveling)

Fig. 5 is a graph showing measurement of a 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 when the direction in which the lens units 40 are arranged is set to the XY direction as shown in fig. 3.

In the drawing of fig. 5, the 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 the crosses 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 embodiment shown in fig. 3 (b). The position of the gap at the left end of fig. 5 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 μm.

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 μm. 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.

(effects of the embodiment)

In this way, 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 considerably smaller than 50 μm in the comparative method.

The positional deviation of the gap D extending in one direction in the direction orthogonal to the one direction was 1.5 μm, which was considerably smaller than 6.5 μm in the comparative example. That is, the straightness of the gap D between the adjacent lens units 40 is high.

Therefore, in the embodiment, the generation of scattered light due to the influence of the gap D of the fly-eye lens 4 is suppressed to be very small as compared with the comparative method. This makes it possible to sharply reduce the illuminance at the outermost periphery of the illumination light of the illumination device 1.

Fig. 6 is a photograph showing an illuminance pattern of light irradiated on a screen when the screen is disposed at a distance of 2m 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. Fig. 7 is a graph in which the luminance at the center in the longitudinal direction of the photograph in the illuminance mode of fig. 6 is expressed in 256 gradations, and a thick line is an embodiment and a thin line is a comparative embodiment.

As shown in the photograph of fig. 6, in the comparative method of fig. 6 (b), the surrounding contour is blurred. However, in the case of the embodiment of fig. 6 (a), the surrounding outline is clear as compared with the comparative method.

In the graph of fig. 7, in the high luminance region in the central portion, there is a change in luminance in the comparative method, and particularly, luminance unevenness occurs at a position indicated by reference numeral 31. However, in the embodiment, the luminance is less fluctuated and substantially uniform in the high luminance region compared with the comparative method.

In the diagram of fig. 7, at the right end of the high luminance region, there is an edge portion abnormal light condensation portion 32 where the brightness temporarily increases further from the substantially constant high luminance region in the comparative method. However, in the embodiment, the luminance is decreased at a time from the substantially constant high luminance region.

In the graph of fig. 7, in the right graph, the rise in luminance is gradual in the portion where the luminance rises from right to left, and in the comparative method, the portion indicated by reference numeral 33. However, in the embodiment, the luminance rises more sharply than in 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.

However, in the embodiment, the gap D between adjacent lens units 40 is narrow, and the straightness is high. Therefore, scattered light is hardly generated, and the outline of the illumination range is clear. Thus, no diaphragm is required. Therefore, the lighting device 1 can be reduced in weight and can be reduced in cost.

Moreover, the ridge line of each lens of the fly-eye lens is clear, and it is not necessary to image the contour of the diaphragm, so that free focus can be achieved.

Therefore, when the lighting device 1 of the embodiment is used for a flashlight, for example, the visibility of the user can be improved by the uniform illuminance distribution. Further, since the illuminance at the outermost periphery of the irradiation range is sharply reduced, only the face of the person facing the irradiation range can be irradiated downward, and the presence of the person can be clearly confirmed while ensuring a state in which the person facing the irradiation range does not feel dazzling.

Further, by setting the divergence angle of the irradiation light to a rectangle having a horizontal angle of 30 ° to 40 ° and a vertical angle of 20 ° to 30 °, a range in which a person can collectively handle the visual field range in the brain can be matched with the irradiation range. This makes it possible to produce effective lighting in guard business and search activities.

In addition, in the case of illumination for signs and advertising boards, since the visibility of an object to be irradiated is improved and light other than the object to be irradiated is substantially absent, it contributes to reduction of light damage by reduction of light leakage and improvement of energy utilization efficiency.

Since the cell size is 500 μm or less, the present invention can be applied to illumination having a subminiature size with an emission end of several millimeters, such as an endoscope.

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 ray deteriorates the irradiation target, deterioration around the irradiation site in a clear irradiation target region can be prevented.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these. For example, the following modifications are possible.

(first modification)

In the embodiment, the shape of the lens unit 40 is set to a constant shape. However, the shape and the arrangement pitch of the lens units 40 may be set to be non-uniform. Fig. 8 is a diagram for explaining a first modification of the embodiment, in which fig. 8 (a) is a diagram showing a case where the shape and arrangement pitch of the lens cells 40 are rectangular and uniform with 330 μm across and 220 μm across, fig. 8 (b) is a diagram showing a first modification in which ± 10% of the shape and arrangement pitch of the lens cells 40 are randomly rearranged on the basis of 330 μm across and 220 μm across, and fig. 8 (C) is an enlarged view of a portion C of fig. 8 (b). The shape of each lens cell 40 randomly rearranged is 4-8-sided polygon, and the lens cell 40 shown in fig. 8 (c) is 8-sided polygon.

FIG. 9 shows the respective luminances (W/mm) in the XY directions when the longitudinal direction of the light emitted from the illumination device 1 is X and the width direction is Y²) Fig. 9 (a) shows the case of fig. 8 (a), and fig. 9 (b) shows the case of fig. 8 (b).

As shown in fig. 8 (b), the shape and arrangement pitch of the lens cells 40 are made non-uniform and random, whereby the edge of the outer periphery of the irradiation field can be blurred.

(second modification)

Fig. 10 is a diagram for explaining a second modification of the embodiment, in which fig. 10 (a) is a diagram showing a case where the arrangement of the lens cells 40 is set to a shape of a uniform hexagonal dense arrangement, and fig. 10 (b) is a diagram showing a second modification in which the shape of the lens cells 40 is set to a uniform hexagonal dense arrangement as a basis and ± 10% thereof are randomly rearranged.

FIG. 11 shows the respective luminances (W/mm) in the XY directions when the longitudinal direction of the light emitted from the illumination device 1 is X and the width direction is Y²) Fig. 11 (a) shows the case of fig. 10 (a), and fig. 11 (b) shows the case of fig. 10 (b).

As shown in fig. 10 (a), this is a diagram showing an example in which the arrangement of the lens units 40 is set to a hexagonal dense arrangement. By setting the arrangement of the lens cells 40 to a hexagonal dense arrangement in this manner, the irradiation range can be set to a 6-sided polygon. As shown in fig. 10 (b), similarly to the first modification, the shape and arrangement pitch of the lens units 40 are made uneven and random, thereby making it possible to blur the edge of the outer periphery of the irradiation field.

The first modification and the second modification are used when there is an edge in the irradiation range for landscape or viewing purposes, and thus illumination in which the irradiation range and the irradiated range smoothly transition is desired. In this case, as shown in fig. 8 (b) and 10 (b), the shape and arrangement pitch of the lens units 40 are set to be uneven and random, and the degree of blurring in the outer periphery can be adjusted, thereby providing the illumination device 1 suitable for applications such as landscape illumination and viewing.

Claims

1. An illumination device having:

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 is incident, the fly-eye lens including a plurality of lens units two-dimensionally arranged on an incident side of the light and a plurality of lens units on an emission side two-dimensionally arranged so as to face the respective lens units on the incident side,

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.

2. The lighting device of claim 1,

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.

3. The lighting device according to claim 1 or 2,

the arrangement pitch of the lens units is not uniform.

4. The lighting device according to any one of claims 1 to 3,

the size of one side of the lens unit is 1/50-1/100 of the size of one side of the fly-eye lens.

5. The lighting device according to any one of claims 1 to 4,

the light source is a light source generating visible light.

6. The lighting device according to any one of claims 1 to 4,

the light source is a light source generating infrared light.

7. The lighting device according to any one of claims 1 to 4,

the light source is a light source generating ultraviolet light.