JP3661798B2 - Lighting device - Google Patents

Description

[0001]
It relates illumination device used the present invention is to the camera, especially in particular, to a lighting apparatus capable of changing the irradiation angle.
[0002]
[Prior art]
A strobe lighting device used for a camera or the like basically includes a light source and optical members such as a reflecting mirror and a prism that guide diverging light emitted from the light source to the front side.
[0003]
In such an illuminating device, if the illumination angle is far from the angle of view of the camera, the amount of illumination at the peripheral edge within the angle of view is insufficient, or conversely, a lot of light is outside the angle of view. There arises a problem that the light utilization efficiency is lowered by irradiation.
[0004]
Therefore, various lighting devices that can change the irradiation angle have been proposed in the past.
(1) As disclosed in Japanese Patent Laid-Open No. 4-138439, a prism having a total reflection surface that reflects light emitted from a light source laterally or rearward toward the front side, and a reflecting member disposed outside the prism In contrast, the one that relatively moves the light source in the direction of the irradiation optical axis,
(2) As shown in JP-A-6-160947, a condensing Fresnel lens having an aperture through which a reflecting mirror equipped with a light source can pass, and another condensing Fresnel lens arranged on the front side thereof, And moving the light source and the reflecting mirror in the axial direction of the opening, that is, the irradiation optical axis direction,
(3) As shown in Japanese Patent Publication No. 5-29895, Japanese Patent Laid-Open No. 6-138522, and Japanese Examined Patent Publication No. 62-51453,
Etc.
[0005]
[Problems to be solved by the invention]
However, in the configuration of (1), since the reflecting member is provided outside the prism, there is a problem that the apparatus becomes large and the cost increases.
[0006]
In the configuration (2), the light source and the reflecting mirror must be moved greatly in order to make the irradiation angle variable, and two condensing Fresnel lenses having a large diameter are required. There was a problem that the enlargement of the size was inevitable.
[0007]
Further, the configuration (3) has a problem that the degree of freedom in setting the light distribution characteristics is low because there is no means for independently controlling the light directly directed from the light source to the subject.
[0008]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an illuminating device that can be formed in a small size and that can obtain a high zoom effect (an irradiation angle change effect) with a small amount of movement. Is.
[0009]
[Means for Solving the Problems]
Ru good to the present invention lighting apparatus, the lighting device for a camera for irradiating a divergent light emitted from the light source as described above to the front,
A lens that focuses light emitted mainly from the light source forward,
Each of the incident surface on which light emitted obliquely forward from the light source is incident, a total reflection surface that totally reflects light that has passed through the incident surface to the front side, and light that is totally reflected by the total reflection surface A pair of emission surfaces that are formed so as to be rotatable about a predetermined rotation axis so as to make the inclination with respect to the irradiation optical axis variable, and arranged so as to sandwich the lens from the outside. Prism ,
A reflector that mainly reflects light emitted from the light source almost backwards to the front ,
A drive member that changes the inclination of the pair of prisms in conjunction with a zoom mechanism of a camera taking lens;
A translucent cover formed integrally with the lens and covering the front side of each exit surface of the pair of prisms;
A holding member holding the light source and the reflecting mirror, and
A lens frame for holding the translucent cover and the lens;
The lens frame and the holding member are combined and integrated with each other, and the lens frame and the holding member have a shape that forms a portion that supports the rotating shaft in an integrated state .
[0010]
In the illumination device according to the present invention, the light source is a straight tubular arc tube having a longitudinal direction, the lens is a cylindrical lens extending in the longitudinal direction of the light source, and the prism extends in the longitudinal direction of the light source. It is preferable that
[0011]
The pair of prisms are preferably arranged such that light emitted from the exit surface irradiates the opposite side across the irradiation optical axis. On the other hand, it is desirable that the lens be movable in the irradiation optical axis direction.
[0012]
[Operation and effect of the invention]
In each lighting device of the present invention having the above-described configuration, light mainly emitted forward from the light source is collected by the lens and always irradiates the central portion of the irradiation angle range. On the other hand, the light emitted obliquely forward from the light source passes through the pair of prisms and exits forward. When the inclination of the prism with respect to the irradiation optical axis is changed, the direction of the light emitted therefrom is changed. Can be changed.
[0013]
Therefore, if the inclination of the prism is set so that the light emitted from the prism irradiates the same position as or close to the light emitted from the lens, it is suitable for the case where the photographing lens of the camera is on the telephoto side. If the angle of the prism is set so that the light emitted from the prism illuminates the outside of the light emitted from the lens, a wide illumination angle suitable for the case where the camera lens is on the wide angle side Become.
[0014]
Note that light emitted almost rearward from the light source is reflected by the reflecting mirror and is incident on the lens or prism, so that the light collection efficiency is kept high. Further, since the total reflection at the prism has a higher reflection efficiency than the reflection at the reflection mirror, the illumination device of the present invention increases the utilization efficiency of the light emitted from the light source as compared with the illumination device using the conventional reflection mirror. be able to.
[0015]
As described above, the illumination device of the present invention can change the irradiation angle by changing the inclination of the prism with respect to the irradiation optical axis, so that it can be compared with a device that greatly moves the light source and the reflecting mirror in the irradiation optical axis direction. Thus, a high zoom effect can be obtained with a small amount of movement, and a small size can be formed.
[0016]
In the illumination device of the present invention, the light emitted mainly forward from the light source and the light emitted obliquely forward are directed in a desired direction by the lens and the prism, respectively, so that the irradiation angle can be changed efficiently. it can.
[0017]
The lighting device that by the present invention, when the light reflecting member is not disposed on the outside of the flop rhythm, particularly remarkable miniaturization is achieved.
[0018]
In lighting device Ru good in the present invention is also the driving member to vary the inclination of the prism in conjunction with the zoom mechanism of the camera taking lens is provided, by performing the zooming operation of the photographing lens, accordingly An optimum irradiation angle can be automatically obtained.
[0019]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. Prior to that, a reference example for explaining the present invention will be described. 1, 2 and 3 show the side shape of a strobe lighting device which is a first reference example for the present invention. The devices shown in these figures are the same as each other. FIG. 1 shows a state at a wide irradiation angle, FIG. 2 shows a state at a narrow irradiation angle, and FIG. Shows the trajectory.
[0020]
This strobe illuminating device is a pair of straight tubular light sources 10 such as Xe (xenon) tubes, for example, and a pair disposed in front of the center of the light source 10 and extending along the longitudinal direction of the light source 10 (direction perpendicular to the paper surface). The transparent material prisms 11 and 12, the reflecting mirror 13 disposed from the rear to the side of the light source 10, and extending along the longitudinal direction of the light source 10 and sandwiched between the prisms 11 and 12 in front of the light source 10 And a dust-proof cover 15 disposed in front of the cylindrical lens 14 and the prisms 11 and 12. In the figure, 16 is a light emission control trigger.
[0021]
The upper prism 11 has an incident surface 11a, a total reflection surface 11b, an exit surface 11c, and a rotation shaft 11d extending in the prism longitudinal direction. As the cross-sectional shape of the total reflection surface 11b, an ellipse, an arc, a combination of a plurality of arcs, a plane, or a combination of these can be employed. Similarly to the upper prism 11, the lower prism 12 has an entrance surface 12a, a total reflection surface 12b, an exit surface 12c, and a rotating shaft 12d extending in the prism longitudinal direction. The reflecting mirror 13 can be formed of an aluminum plate or a molded component obtained by vapor-depositing aluminum. As the cross-sectional shape, an ellipse, a hyperbola, an arc, a combination of a plurality of arcs, or a combination of these can be adopted. The cylindrical lens 14 has an entrance surface 14a that is a positive refracting surface and an exit surface 14b.
[0022]
As shown in FIGS. 1 and 2, light mainly emitted forward from the light source 10 is incident on a cylindrical lens 14, and is condensed in a plane parallel to the paper surface by the cylindrical lens 14 and emitted forward. The object is irradiated through the dust cover 15. Further, light emitted obliquely forward and upward from the light source 10 is incident on the incident surface 11a of the prism 11, and after passing there, is totally reflected by the total reflection surface 11b. The light totally reflected by the total reflection surface 11b is emitted forward from the emission surface 11c, and irradiates the object on the opposite side, that is, the lower side with the irradiation optical axis O in between. On the other hand, although not shown, the light emitted obliquely forward and downward from the light source 10 is incident on the incident surface 12a of the prism 12, and after passing there, is totally reflected by the total reflection surface 12b. The light totally reflected by the total reflection surface 12b is emitted forward from the emission surface 12c, and irradiates the subject on the opposite side, that is, the upper side with the irradiation optical axis O in between.
[0023]
The prisms 11 and 12 can be rotated about the rotation axes 11d and 12d, respectively. For example, the prisms 11 and 12 are rotated in conjunction with the zoom lens of the camera or manually, and the zoom lens is set to the wide angle side. When the zoom lens is set to the telephoto side, the rotation position shown in FIG. 2 is set.
[0024]
FIG. 4 shows the relationship between the light irradiation range on the object plane P by the strobe lighting device and the field angle of view by the zoom lens of the camera. In the figure, W represents a shooting field angle when the zoom lens is set to the wide angle side (hereinafter referred to as a wide field angle), and T represents a shooting field angle when the zoom lens is set to the telephoto side ( This is hereinafter referred to as a tele angle of view).
[0025]
In the state of FIG. 1, the light emitted from the cylindrical lens 14 is slightly larger than the tele angle of view T in the region 1 in FIG. 4, that is, the direction in which the irradiation angle is changed (Y direction). An area slightly larger than the wide field angle W is irradiated in a direction (X direction) perpendicular to the direction to be generated. In the state of FIG. 1, the light emitted from the upper prism 11 deviates to the lower side of the area 2 in FIG. 4, that is, the tele view angle T in the Y direction, and the wide view angle W in the X direction. Irradiate a slightly larger area. On the other hand, in the state of FIG. 1, the light emitted from the lower prism 12 deviates from the area 3 in FIG. 4, that is, the tele angle of view T in the Y direction, and the wide angle of view W in the X direction. Irradiate a slightly larger area.
[0026]
As described above, when the zoom lens of the camera is set to the wide angle side, the light emitted from the prisms 11 and 12 and the cylindrical lens 14 is irradiated onto a region that substantially matches the wide field angle W. . FIG. 5 shows an outline of the illuminance distribution in the Y direction at this time. Curves 1, 2, and 3 in FIG. 5 show the illuminance distribution in regions 1, 2, and 3 in FIG. 4, respectively, and the entire illuminance distribution is shown by a broken line that combines them.
[0027]
When the zoom lens of the camera is set to the telephoto side, the upper prism 11 is rotated clockwise in FIG. 1 about the rotation axis 11d, and the lower prism 12 is rotated counterclockwise about the rotation axis 12d. It is rotated and set to the rotation position of FIG.
[0028]
In the state of FIG. 2, the light emitted from the cylindrical lens 14 irradiates the region 1 in FIG. 4 without changing from the state of FIG. Further, the light emitted from the upper prism 11 is gradually changed in the direction in which the angle formed with the irradiation optical axis O becomes smaller as the prism 11 rotates, and in the state of FIG. Irradiate almost the same area. Similarly, the light emitted from the lower prism 12 irradiates a region substantially the same as the region 1 in FIG.
[0029]
As described above, when the zoom lens of the camera is set to the telephoto side, the light emitted from the prisms 11 and 12 and the cylindrical lens 14 substantially coincides with the tele angle of view T in the Y direction, and in the X direction. Is irradiated to an area substantially coincident with the wide field angle W, and the illuminance of the irradiation range becomes higher. FIG. 6 shows an outline of the illuminance distribution in the Y direction at this time. Curves 1, 2, and 3 in FIG. 6 indicate the illuminance distribution in regions 1, 2, and 3 in FIG. 4, respectively, and the entire illuminance distribution is displayed in a broken line that combines them.
[0030]
In the reference example described above, the exit surfaces 11c and 12c of the prisms 11 and 12 and the exit surface 14b of the cylindrical lens 14 are flat. However, as shown in FIG. , 12c and 14b can be made into vertical Fresnel lens shapes to collect light in a direction perpendicular to the direction in which the irradiation angle is changed.
[0031]
Also, each end face of the prisms 11 and 12 facing the cylindrical lens 14 and the end face of the cylindrical lens 14 facing the prisms 11 and 12 are mirror-finished so that the light passing through them is totally reflected. It is preferable to do this.
[0032]
In this reference example, as shown in FIG. 3, the light emitted substantially rearward from the light source 10 is reflected by the reflecting mirror 13 and is mainly incident on the cylindrical lens 14, so that the light collection efficiency is kept high. However, the present invention is not limited to this, and the light reflected by the reflecting mirror 13 may be mainly incident on the prisms 11 and 12.
[0033]
Furthermore, it is also possible to change the irradiation angle in the X direction of FIG. 4 by arranging the light source 10 in the direction in which the longitudinal direction extends vertically.
[0034]
Next, a second reference example for the present invention will be described with reference to FIGS. In these figures, the devices themselves are the same as each other. FIG. 8 shows a state at a wide irradiation angle, FIG. 9 shows a state at a narrow irradiation angle, and FIG. The locus of the emitted light is shown. In these drawings, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted unless necessary (the same applies hereinafter).
[0035]
The strobe lighting device of the second reference example uses prisms 21 and 22 different from those of the first reference example device. In this case as well, the upper prism 21 has an incident surface 21a, a total reflection surface 21b, and an exit surface 21c. However, the rotating shaft 21d is different from the first reference example in that the cylindrical lens 14 and It is provided in the vicinity of the front edge of the opposing surface. Similarly to the upper prism 21, the lower prism 22 has an entrance surface 22a, a total reflection surface 22b, an exit surface 22c, and a rotating shaft 22d.
[0036]
These prisms 21 and 22, the total reflection surface 21b, respectively, 22b slope of is set to be relatively small, it is to allow a smaller vertical dimension y _p of the prism front surface. However, since the irradiation angle becomes too wide as it is, in order to correct this, the exit surfaces 21c and 22c are inclined to refract the emitted light so that the angle formed with the optical axis becomes small. Such prisms 21 and 22 are advantageous in reducing the size of the apparatus.
[0037]
Next, the actual施例of the present invention. FIG. 11 shows a side shape of a strobe lighting device according to an embodiment of the present invention. In real施例device this, the upper prism 31 has an input surface 31a, and the total reflection surface 31b, and an exit surface 31c, and a rotation shaft 31d. Similarly to the upper prism 31, the lower prism 32 has an incident surface 32a, a total reflection surface 32b, an exit surface 32c, and a rotation shaft 32d.
[0038]
On the other hand, the cylindrical lens 34 is extended greatly up and down so that the front end is located on the front side of the exit surfaces 31c and 32c of the prisms 31 and 32, respectively. In the first reference example device described above, there is a gap between the cylindrical lens 14 and the prisms 11 and 12, and therefore it is necessary to provide a dustproof cover 15 in order to prevent entry of dust into the gap ( Similarly in the second reference example device), since the cylindrical lens 34 in the shape in the present embodiment also functions as a dustproof cover, there is no need to separately provide a dust-proof cover. If so, the light emitted from the cylindrical lens 34 does not have to pass through a separate dustproof cover, so that the transmission efficiency is improved.
[0039]
Indeed a state incorporated in the camera strobe lighting device above you施例shown in FIGS. 12 and 13. FIG. 12 shows a state at a wide irradiation angle, and FIG. 13 shows a state at a narrow irradiation angle. FIG. 14 is an exploded view showing a mechanism for incorporating the strobe lighting device.
[0040]
As shown in these drawings, the cylindrical lens 34 is attached to a lens frame 35, and the lens frame 35 is fixed to the camera body 30. Alternatively, the cylindrical lens 34 and the lens frame 35 may be integrally formed. 12 and 13, the side plate on the front side of the lens frame 35 is omitted. A pair of recesses 35a, 35a is provided on the upper back of the lens frame 35, and the upper prism 31 is disposed in the lens frame 35 with the rotation shafts 31d, 31d being housed in these recesses 35a, 35a. A pair of recesses 35b, 35b is also provided at the lower back of the lens frame 35, and the lower prism 32 is disposed in the lens frame 35 with the rotation shafts 32d, 32d being housed in these recesses 35b, 35b. A case 40 is attached to the rear side of the lens frame 35, and shaft pressing portions 40a provided on the left and right sides of the case 40 close the open ends of the recesses 35a, 35a, 35b, and 35b. As a result, the upper prism 31 and the lower prism 32 are held so as to be rotatable about the rotation shafts 31d and 32d, respectively.
[0041]
An arm 36 is fixed to one rotating shaft 31d of the upper prism 31, and a prism driving lever 37 engaging with the arm 36 is fixed to one rotating shaft 32d of the lower prism 32. A torsion spring 38 is fitted on the one rotation shaft 31d. One end of the torsion spring 38 is locked to the projection 35c of the lens frame 35, and the other end is locked to the projection 36a of the arm 36, so that the upper prism 31 rotates counterclockwise in the figure around the rotation shaft 31d. It is energized. The prism drive lever 37 is urged to rotate clockwise in the figure around the rotation axis 32d together with the lower prism 32 by receiving the urging force of the arm 36.
[0042]
A light source 10 and a reflecting mirror 13 are attached to the case 40 using a silicon band 39, and a trigger 16 is attached. Two pins 40b and 40c are projected from the back surface of the case 40. The cam plate 41 is disposed so as to be movable in the longitudinal direction of the long holes 41b and 41c by accommodating these pins 40b and 40c in the long holes 41b and 41c, respectively.
[0043]
The cam plate 41 has an inclined cam surface 41a at the upper part of one end, and a rack 41d at the lower part of the other end. The lower end portion of the prism drive lever 37 that is urged to rotate as described above is in elastic contact with the cam surface 41a. The rack 41d is engaged with a gear 43 that is rotated by a lens barrel drive ring 42 that operates a zoom lens of the camera.
[0044]
In the above configuration, when the lens barrel drive ring 42 is in the rotation position for setting the zoom lens of the camera to the wide angle side, the cam plate 41 is positioned relatively on the rear side in FIG. Therefore, the tip of the prism drive lever 37 that is in contact with the cam surface 41a of the cam plate 41 is lowered to a relatively low position, and the prisms 31 and 32 are set to the rotational positions shown in FIG. In this case, a wide irradiation angle can be obtained.
[0045]
On the other hand, when the lens barrel drive ring 42 is rotated so as to set the zoom lens of the camera to the telephoto side, the cam plate 41 moves to the near side in FIG. Therefore, the tip of the prism drive lever 37 that is in contact with the cam surface 41a of the cam plate 41 is pushed up to a relatively high position, and the prisms 31 and 32 are set to the rotational positions shown in FIG. In this case, a narrow irradiation angle can be obtained.
[0046]
Next, a third reference example for the present invention will be described with reference to FIGS. The strobe lighting device of the third reference example is different from the first reference example device described above in that the cylindrical lens 14 is movable in the direction of the irradiation optical axis O. FIG. 15A shows a state where the third reference example apparatus obtains a wide irradiation angle, and FIG. 16 shows a state where the third reference example apparatus obtains a narrow irradiation angle. For comparison, FIG. 15B shows a state in which the first reference example apparatus obtains a wide irradiation angle.
[0047]
When obtaining a particularly wide irradiation angle, as shown in FIG. 15A, the upper prism 11 and the lower prism 12 are operated to a wider irradiation angle side than the state of FIG. That is, the upper prism 11 is further rotated counterclockwise about the rotation axis 11d, and the lower prism 12 is further rotated clockwise about the rotation axis 12d. Then, the illumination area by the upper prism 11 (area 2 in FIG. 4) and the illumination area by the lower prism 12 (area 3 in FIG. 4) move away from the center of the angle of view, that is, in a direction to further enlarge the irradiation angle. .
[0048]
However, the regions 2 and 3 in FIG. 4 are separated from the region 1 as it is, and dark portions with low illuminance are generated between the regions. Therefore, when the cylindrical lens 14 is moved in the direction approaching the light source 10, the region 1 expands in the Y direction in FIG. 4 and the dark portion disappears.
[0049]
As shown in FIG. 16, when the upper prism 11 and the lower prism 12 are in a state of obtaining a particularly narrow irradiation angle and the cylindrical lens 14 is moved in a direction away from the light source 10, the region 1 becomes as shown in FIG. 4. In the Y direction, and a narrower irradiation angle can be obtained.
[0050]
In general, when the lens is moved away from the light source, the light rays incident on the lens are reduced, and unnecessary light is increased. However, in this reference example device, light that does not enter the cylindrical lens 14 (FIG. 16). Since the light beam a) enters the prisms 11 and 12, the light utilization efficiency does not deteriorate.
[0051]
Next, a fourth reference example for the present invention will be described with reference to FIG. The strobe lighting device of the fourth reference example is different from the first reference example device described above in that another function is added to the rotating mechanism of the upper prism 11 and the lower prism 12. is there. In other words, the rotating mechanism of the upper prism 11 and the lower prism 12 is mechanically connected to, for example, a parallax correction lever of a camera operated during close-up shooting, and the prisms 11 and 12 are identical to each other during close-up shooting. It is rotated in the direction. For example, during wide-angle shooting, if the prisms 11 and 12 are rotated counterclockwise in the figure around the rotation axes 11d and 12d, respectively, the irradiation range moves downward.
[Brief description of the drawings]
FIG. 1 is a side view showing a state at a wide irradiation angle of a lighting device as a first reference example according to the present invention. FIG. 2 is a side view showing a state at a narrow irradiation angle of the first reference example device. FIG. 4 is a side view showing the state of the first reference example device at a wide irradiation angle together with a ray trajectory different from that in FIG. 1. FIG. 4 explains the relationship between the field of view on the subject surface and the light irradiation range. FIG. 5 is a schematic diagram showing the illuminance distribution on the subject surface at a wide illumination angle. FIG. 6 is a schematic diagram showing the illuminance distribution on the subject surface at a narrow illumination angle. FIG. 7 is a prism used in the present invention. narrow irradiation angle of the side view and FIG. 9 the second reference example device showing a state during wide illumination angle of the second is a reference example lighting device for a lens another perspective view showing an example [8] the present invention state during wide irradiation angle of a side view and FIG. 10 the second reference example device showing a state when, shown together different beam trajectories and 8 Surface view [11] You施例device on incorporated in the side view [12] camera showing a main part of an illumination device according to an embodiment of the present invention, partially cut away showing a state when a wide irradiation angle side view 13 of you施例device on incorporated in the camera, exploded perspective view of a cutaway side view and FIG. 14 on you施例device portion showing a state when a narrow illumination angle [15] state during wide illumination angle of the illumination apparatus as a third reference example relative to the present invention, a state when a narrow illumination angle of the first side view in comparison with the reference example device [16] the third reference example device FIG. 17 is a side view of a lighting apparatus according to a fourth reference example of the present invention.
10 Light source
11, 21, 31 Upper prism
11a, 21a, 31a Incident surface of upper prism
11b, 21b, 31b Total reflection surface of upper prism
11c, 21c, 31c Emitting surface of upper prism
11d, 21d, 31d Upper prism rotation axis
12, 22, 32 Lower prism
12a, 22a, 32a Entrance surface of lower prism
12b, 22b, 32b Total reflection surface of lower prism
12c, 22c, 32c Lower prism exit surface
12d, 22d, 32d Lower prism rotation axis
13 Reflector
14, 34 Cylindrical lens
15 Dust cover
16 trigger
30 Camera body
35 Lens frame
36 arms
37 Prism drive lever
38 Torsion spring
39 Silicon band
40 cases
41 Cam plate
42 Lens barrel drive ring

Claims (4)

In the camera illumination device that irradiates the divergent light emitted from the light source forward,
A lens that mainly collects light emitted forward from the light source;
Each is an incident surface on which light emitted obliquely forward from the light source is incident, a total reflection surface that totally reflects light that has passed through the incident surface to the front side, and light that is totally reflected by the total reflection surface And a pair of surfaces arranged so as to be rotatable about a predetermined rotation axis so as to make the inclination with respect to the irradiation optical axis variable and sandwich the lens from the outside. Prism ,
A reflecting mirror that mainly reflects light emitted substantially backward from the light source forward ;
A drive member that changes the inclination of the pair of prisms in conjunction with a zoom mechanism of a camera taking lens;
A translucent cover formed integrally with the lens and covering the front side of each exit surface of the pair of prisms;
A holding member holding the light source and the reflecting mirror, and
Comprising a lens frame for holding the translucent cover and the lens;
An illumination device , wherein the lens frame and the holding member are combined and integrated with each other, and have a shape that constitutes a portion that supports the rotating shaft in an integrated state . The light source is a straight tubular arc tube having a longitudinal direction, the lens is a cylindrical lens extending in the longitudinal direction of the light source, and the prism extends in the longitudinal direction of the light source. The lighting device according to 1 . 3. The illumination device according to claim 1, wherein each of the pair of prisms is arranged such that light emitted from the emission surface irradiates the opposite side across an irradiation optical axis. The illumination device according to any one of claims 1 to 3 , wherein the lens is movable in an irradiation optical axis direction.

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