JP2002148687A - Illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more efficiently condense light toward an object, as for an illuminating device where a comparatively narrow light distribution is required. SOLUTION: As for a prism unit 23, transmissive/total reflection surfaces αand β crossing each other are formed by using at least one prism (four prisms 23a to 23d in figure), the light emitted from a light source 22 is made incident on the prism unit 23, and the light is transmitted or totally reflected by the transmissive/total reflection surfaces α and β in accordance with an incident angle θ, then, the transmitted light is emitted ahead, and the totally reflected light goes toward the side part. A reflecting member 21 is arranged on the side part so as to surround the prism unit 23, and the light totally reflected to the side part by the prism unit 23 is reflected ahead by the reflecting member 21, then, the light emitted from the light source 22 is efficiently condensed ahead in a narrow effective area with the combination of the prism unit 23 and the reflecting member 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device, and more particularly to an illuminating device that illuminates a subject with illuminating light (flash light) when photographing with a camera.

[0002]

2. Description of the Related Art Conventionally, when photographing with a camera,
2. Description of the Related Art An illumination device that irradiates illumination light (flash light) to a subject side is used in nighttime shooting, indoor shooting, or shooting in backlight.

[0003] Such an illuminating device is mounted on a part of a camera body, and illuminating light (flash light) is radiated to a subject side in conjunction with a photographing operation of the camera to perform photographing.

FIGS. 14 and 15 are sectional views of a conventional lighting device. In the illumination device 10 shown in these figures, a cylindrical flash arc tube 12 such as a xenon (Xe) tube is disposed inside a back side 11a of a reflector 11 having a radial cross section, and the longitudinal direction of the reflector 11 is the center of the reflector 11. It is arranged so as to be orthogonal to the axis 13. What regulates the direction of light rays from the light emitting portion of the flash arc tube 12
Only the reflector 11 including the back side 11a is included. The light from the light emitting portion of the flash tube 12 is emitted directly to the outside of the reflector 11 without being reflected by the inner wall of the reflector 11, and is also emitted to the outside of the reflector 11 by being reflected by the inner wall of the reflector 11. There is something. Also,
Some leak to the outside through the gap between the reflector 11 and the flash arc tube 12 (indicated by a cross).

FIG. 14 shows a number of light beams emitted from the center point O of the light emitting portion of the flash arc tube 12 at different angles. FIG. 15 shows the center point O of the light emitting portion of the flash arc tube 12.
The figure shows a number of light rays emitted at different angles from a light emitting point A shifted from the light emitting point A. While there is a light beam emitted from each light emitting point directly to the outside through the interior of the reflector 11, there is a light beam reflected on the inner surface of the reflector 11 and emitted to the outside, and from each light emitting point to the reflector back side 11a. There are rays. Light rays traveling from each light emitting point toward the reflector back side 11a are reflected by the inner surface of the reflector back side 11a, and then pass through the inside of the reflector 11 as they are to form the aperture 11a.
b, the light reflected from the inner surface of the reflector 11 and then emitted from the opening 11b, and the light reflected from the inner surface of the reflector 11 from both sides of the flash tube 12 or without being reflected from the inner surface of the reflector 11. And a light beam emitted to the outside through a gap between the light emitting tube 12 and the flash arc tube 12 (this light beam does not effectively act on the subject side).

Regarding any ray passing through the reflector 11, the angle shown in the figure attached to each ray is the ray emitted from the radially opened opening 11 b of the reflector 11 toward the subject (not shown) (upward in the figure). Irradiation angle (irradiation center axis 1
(Angle to 3). Here, assuming that the irradiation angle required for a relatively narrow light distribution corresponding to the angle of view of the photographing lens to be used is, for example, 16 °, a ray indicated by a number larger than 16 ° among a plurality of angles shown in FIG. This is a light ray that is out of the desired photographing range with respect to the subject side and does not effectively act on the subject side at the time of photographing. In the conventional illuminating device shown in FIGS. 14 and 15, there were many light beams having an irradiation angle exceeding the effective range of 0 ° to 16 °, and the irradiation efficiency was poor.

Therefore, proposals have been made to improve the irradiation efficiency or the irradiation characteristics. For example, Japanese Patent Laid-Open No. 4-1
Japanese Patent No. 38440 discloses an illumination device that radiates divergent light from a cylindrically long discharge tube forward, in which prisms are arranged on both front sides of the discharge tube to collect light directed in the longitudinal direction of the discharge tube forward. A configuration for lighting is described.

In Japanese Patent Application Laid-Open No. 10-115585, a plurality of light guide prisms are arranged in front of a light emitting portion, or a single prism is provided with a groove to obtain a plurality of light guide effects. The configuration is described.

On the other hand, a lighting device for a camera requires a lighting device having an irradiation angle corresponding to the angle of view of a photographing lens (wide-angle, standard, telephoto, etc.) used for the camera.

[0010]

However, in Japanese Patent Application Laid-Open No. 4-138440, in a configuration in which only prisms are arranged on both front sides of a discharge tube, as shown in FIG. When the light beam emitted forward without passing through the prism from the prism goes straight without refracting or reflecting the space between the prisms on both sides, the irradiation range is wide, and when light distribution in a narrow range is required Cannot collect light efficiently. Also, rather than the arc length of the discharge tube,
Since it is necessary to set the distance between the prisms arranged on both sides of the discharge tube to be wide, there is a problem that when trying to obtain a narrow light distribution with a large-energy arc tube having a long arc length, the irradiation efficiency is poor.

Further, in this publication, as shown in FIG. 3A, a type in which a reflecting member is further provided inside the prism is disclosed, but a reflecting surface having a complicated shape must be formed. There is a problem. Furthermore, this type also has a problem that it is not always possible to efficiently collect light in order to obtain a narrow light distribution.

In Japanese Patent Application Laid-Open No. 10-115853, a light beam is only emitted using the total reflection of a light guide, and light is emitted radially as a whole from an exit surface facing the entrance surface of the light guide. Since the light is emitted, there is a problem that it is difficult to efficiently collect light in a narrow range.

In view of the above problems, it is an object of the present invention to provide an illumination device that requires a relatively narrow light distribution and that can more efficiently condense light on the subject side. .

[0014]

According to a first aspect of the present invention, there is provided an illuminating device for radiating divergent light from a light source forward, comprising: an incident surface on which the light from the light source is incident; and a light passing through the incident surface. A prism having a transmission / total reflection surface capable of transmitting or totally reflecting according to an incident angle, emitting transmitted light forward and directing the totally reflected light to the side; And a reflecting member for reflecting light totally reflected laterally by the reflecting surface to the front.

According to the first aspect of the present invention, in the prism,
Light from the light source is incident, transmitted or totally reflected by the transmission / total reflection surface according to the incident angle, and the transmitted light is emitted forward,
The light that is totally reflected is directed to the side, and the reflecting member reflects the light that is totally reflected sideways by the prism forward, so the combination of the prism and the reflecting member identifies the light from the light source ahead. Can be efficiently ejected into the range.

According to a second aspect of the present invention, there is provided an illuminating device for radiating divergent light from a flash lamp having a long cylindrical shape forward, wherein the illuminating device is disposed in front of the flash lamp and radiates from the flash lamp. Light can be transmitted or totally reflected in accordance with the incident angle, and the transmitted light is emitted forward and substantially the entire region in the longitudinal direction of the flash arc tube so that the totally reflected light is directed to the side. And a prism having a transmission / total reflection surface provided over the entire surface.

According to the second aspect of the present invention, a prism having a transmission / total reflection surface is disposed in front of a flash tube having a long cylindrical shape over substantially the entire area in the longitudinal direction of the flash tube. Of the light is transmitted or totally reflected by the transmission / total reflection surface according to the incident angle, the light transmitted by the prism is emitted forward, and the light totally reflected is directed to the side. I made an orientation. This allows the light that is totally reflected by the prism and directed to the side to be directed forward using other means, so that the light can be efficiently condensed to a specific area in front. Becomes possible.

According to a third aspect of the present invention, in the illumination device according to the second aspect, the transmission / total reflection surface is substantially line-symmetric with respect to a central axis of the illumination device in a longitudinal direction of the flash arc tube. A first transmission / total reflection surface and a second transmission / total reflection surface are formed, and the first and second transmission / total reflection surfaces intersect each other near the irradiation center axis. I do.

According to the third aspect of the present invention, the transmission / total reflection surface existing over substantially the entire area in the longitudinal direction of the flash arc tube in front of the flash arc tube having a cylindrical shape is formed in the longitudinal direction of the flash arc tube. The first transmission / total reflection surface and the second transmission /
While the first and second transmission / total reflection surfaces are formed so as to intersect with each other in the vicinity of the irradiation center axis, light is emitted on both the left and right sides with respect to the irradiation center axis of the flash tube. The incident light enters the prism,
The light is transmitted or totally reflected by the second transmission / total reflection surface, and the transmitted light and the total reflection light form symmetrical light rays about the irradiation center axis on both the left and right sides. Light that has been totally reflected by the transmission / total reflection surface and directed to the side can be efficiently condensed to a narrow area in front by using other means to direct the light forward. Becomes possible.

[0020]

Embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a prism unit including a plurality of prisms is disposed inside the reflector, and a narrow air layer is arranged in a cross shape in the prism unit so that light can be efficiently collected. It was done.

Before describing the lighting apparatus according to an embodiment of the present invention with reference to FIGS. 1 and 2, the basic principle of the present invention will be described with reference to FIGS.

In the embodiment shown in FIGS. 1 and 2, the prism unit 23 composed of four separate prisms (23a, 23b, 23c, 23d) is disposed inside the reflector 21. 6, half of the prism unit 2
31 (this is a 1 that is located close to the flash arc tube 22)
A description will be given of a configuration in which a wedge-shaped prism composed of two prisms and another prism arranged to face one surface of the prism, and an air layer of two prism surfaces is omitted here, is combined with a reflector 21. I do.

FIGS. 14 and 15 show the configurations of FIGS.
A major difference from the conventional example is that a wedge-shaped prism 231 is provided in the reflector. The wedge-shaped prism 231 is disposed substantially in parallel so that one surface (incident surface) μ is close to the flash arc tube 22 in the longitudinal direction of the flash arc tube 22, and the other surface γ is the inner surface of the reflector 21. (Right side in the figure). That is, the incident surface μ of the wedge-shaped prism 231 is arranged along the longitudinal direction (tube axis direction) of the light emitting portion 22a of the flash light emitting tube 22 and beyond the light emitting range of the light emitting portion 22a. The other surface α connecting one end of the incident surface μ and one end of the surface γ in the wedge-shaped prism 231 extends from the inner surface of the reflector 21 on the side of the flash arc tube (lower left side in the drawing) to the inner surface of the opening of the reflector 21 ( A certain angle ε with respect to the tube axis direction (longitudinal direction) of the flash tube 22 (upper right side in the figure).
It is an inclined surface.

FIG. 3 is a cross-sectional view showing a light ray path when a light ray emitted from the light emitting point O at the center of the light emitting part 22a of the flash light emitting tube 22 to the right side of the irradiation center axis 24 enters the prism 231. FIG. 4 shows a light emitting section 22a of the flash tube 22.
From the light emitting points A and B at positions off the center of
26 is a cross-sectional view showing a light path when a light beam emitted to the right side of FIG. 26 enters a prism 231. FIG.

3 and 4, the flash tube 22 is a back side 2 of a reflector 21 having a radially open cross section.
The prism 21 is disposed inside the reflector 21 so as to be in contact with the inner surface of the reflector 1a. The prism 231 is the wedge-shaped prism described above (however, two separate prisms 23a and 23b corresponding to half of the prism unit in FIG. 1 described later are combined). θ
1 and θ2 are incident angles at which light is emitted from the light emitting points O, A and B of the light emitting portion 22a of the flash tube 22 to the surface μ of the prism 231. θ1 is a value when the incident light passes through the surface α of the prism 231. The angle of incidence, θ2, is
The angle of incidence when the light is totally reflected by the surface α of No. 1. Therefore,
The critical angle of total reflection exists between θ1 and θ2.

3 and 4, the light beam emitted from the light emitting portion 22a of the flash tube 22 to the right side of the irradiation axes 24, 25 and 26 in the drawing is incident on the incident surface μ of the prism 231 at an incident angle θ.
Is small (for example, a ray having an incident angle θ1), the light passes through the entrance surface μ of the wedge-shaped prism 231 and finally passes through the exit surface α which is the transmission / total reflection surface of the prism 231.
In the case of a light beam having a large incident angle on the incident surface μ of the prism 231 (for example, a light beam having an incident angle θ2), a phenomenon that a total reflection occurs on the transmission / total reflection surface α of the prism 231 newly occurs.

The light totally reflected by the one surface α of the prism 231 is reflected by the reflection surface of the inner surface of the reflector 21, and the reflected light is emitted at a certain angle in the direction of the opening center of the reflector 21 (ie, forward) and is emitted to the outside. Will be irradiated.
That is, even if the irradiation angle corresponding to the incident angle θ to the prism 231 is a light beam larger than a certain angle, FIGS.
In the conventional example of No. 5 (when there is no wedge-shaped prism), the light beam passes through the inside of the reflector and is radiated to the outside while maintaining the irradiation angle, or the light beam in the case of a larger irradiation angle is reflected by the inner surface of the reflector. 3 and FIG. 4, while the irradiation angle corresponding to the incident angle θ to the prism 231 is larger than a certain angle, the light is applied to the prism surface α. There is a ray that is totally reflected, and the ray that has been totally reflected is reflected and changes its direction, and is then reflected by the inner surface of the reflector, and has a function of changing its direction again and pointing toward the center of the reflector. Become.

In other words, in the case of FIG. 3 and FIG. 4, the irradiation axes 24, 25, 26
The light rays irradiated on the right side of the drawing are irradiation axes 24, 25, 2
6 is within a predetermined range (eg, θ1
), The light passes through the surface μ and the surface α of the prism 231 and is radiated from the opening of the reflector 21 to the outside. This is the same as the case where the light from the flash tube light emitting unit in FIGS. 14 and 15 (conventional example) travels through the reflector and is radiated to the outside from the reflector opening except that the light is refracted by the prism. Almost the same. However, as shown in FIGS. 3 and 4, the light beam emitted from the light emitting part 22 a of the flash arc tube 22 to the right side of the irradiation axes 24, 25, 26 in the drawing has a large incident angle θ with respect to the irradiation axes 24, 25, 26. If the distance slightly exceeds the predetermined range (for example, θ2), the light passes through the surface μ of the prism 231 and is totally reflected by the surface α and is reflected toward the inner surface of the reflector 21 to be reflected from the inner surface of the reflector 21 to the outside. Will be irradiated.

Therefore, when only one wedge-shaped prism 231 is provided, the light beam emitted from the light emitting point to the right side of the irradiation axis as shown in FIGS.
If the inclination of 1 is taken into consideration, it is possible to condense light in a narrow range in front of the reflector 21.

FIG. 5 is a sectional view showing a light ray path when a light ray emitted from the light emitting point O at the center of the light emitting portion 22a of the flash light emitting tube 22 to the left side of the irradiation center axis 24 enters the prism 231.

FIG. 5 shows the light beam emitted to the left of the irradiation center axis 24 in the drawing. In this case, the incident light beam I at the angle of incidence θ1 on the incident surface μ is
Similarly to the light beam of the incident angle θ1 (see FIGS. 3 and 4) emitted to the right of
Transmit through the total reflection surface α. The incident angle θ shown in FIG.
2 (where θ2 is the same size as the incident angle θ2 emitted to the right of the irradiation center axis 24)
Does not satisfy the condition of total reflection because the angle at which the light reaches the transmission / total reflection surface α after transmitting
And is emitted through. Therefore, the ray J of the incident angle θ2 emitted to the left of the irradiation center axis 24 is not guided to the inner surface of the reflector 21 after passing through the prism 231 (thus, is not reflected), and is not reflected outside the reflector. Emitted to Therefore, the wedge-shaped prism 231
When only one is provided, the light beam emitted from the light emitting point to the left side of the irradiation axis as shown in FIG.
Even when the irradiation angle from a (that is, the angle of incidence on the surface μ) is large, the light is not totally reflected by the emission surface α, so that the emitted light is emitted in a substantially specific direction (upper left direction in the drawing). Thus, the entire light beam is not necessarily converged in a narrow range. (Note that as a method of solving this poor light-collecting property, a prism 23c (shown by a two-dot chain line in FIG. 5) is disposed so that one surface is in contact with the reflector 21 on the left side in the drawing and the other surface is in contact with the prism 231. For example, the prism 231
Can be totally reflected on the surface β 'of the prism 23c and directed toward the inner surface of the reflector, and can be reflected on the inner surface of the reflector and directed toward the center of the reflector. This will be described later with reference to FIGS. FIG. 5 illustrates the case where the light is emitted from the emission point O at the center of the light emitting portion 22a of the flash tube 22 to the left side of the irradiation center axis 24 in the drawing, but the position is shifted from the center of the light emitting portion 22a. In the case where the light is emitted from the light-emitting point to the left side of the irradiation axis at the light-emitting point in FIG.
The light beam having the incident angle θ2 is also transmitted through the transmission / total reflection surface α. However, the closer the light emitting point of the flash tube 22 is to the left electrode in the drawing of the light emitting portion 22a, the more the light beam of the incident angle θ2
After being transmitted through the reflector, some light is not emitted to the outside of the reflector as it is, but is once reflected by the inner surface of the reflector and directed toward the center of the reflector.

FIG. 6 shows the inclination ε of the reflecting surface α of the prism 231.
FIG. 6 is a diagram showing the relationship between the angle of light and the angle θ of light rays. In this figure, when a light beam emitted from the light emitting point O of the light source to the right side in the drawing of the irradiation center axis 24 enters the prism 231, the light distribution corresponding to the inclination angle ε of the wedge-shaped prism 231 and the shooting angle of view. Is obtained with respect to the incident angle θ of the light beam necessary to obtain

In the configuration of the wedge-shaped prism 231 corresponding to half of the prism unit 23 described in FIGS. 1 and 2 (FIG. 6), the illumination light incident on the wedge-shaped prism 231 from the light emitting portion 22a of the flash tube 22. (Flash) is transmitted or totally reflected on the surface α of the wedge-shaped prism 231 according to the incident angle θ. The action of the illumination light (flash) is achieved by combining the wedge-shaped prism 231 with a wedge-shaped prism 232 (shown by a two-dot chain line in FIG. 6) corresponding to the other half of the prism unit 23. The same applies to a state where a parallel plate prism is formed. In a state where the wedge-shaped prism 231 and the wedge-shaped prism 232 are combined, when the illumination light (flash light) passes through the combined parallel plate-shaped prism, the wedge-shaped prism 232 is set at the same angle θ as the incident angle θ. (FIG. 6)
(See the transmitted light indicated by the two-dot chain line). Therefore, by calculating the relationship between the incident angle θ and the prism inclination angle ε in the state of the half 231 of the prism unit 23 shown by the solid line in FIG. 6, the incident angle θ of light that can pass through the prism unit 23 is calculated. By setting the irradiation angle (the angle required for the light distribution at the time of photographing) corresponding to the angle of view of the photographing lens of the camera using the lighting device, the prism unit half 231 corresponding to the required light distribution angle θ is set. Can be obtained.

In FIG. 6, the refractive index of the prism is n ',
Assuming that the refractive index of the atmosphere is n, n sin θ = n ′ sin θ ′ i is a critical angle at which total reflection occurs. I = sin−1 (n / n ′) Therefore, from FIG. 6, ε = i−θ ′ = sin−1 ( n / n ')-sin-1 (nsinθ /
n ′) For example, when a prism with n ′ = 1.5 is used, ε = 41.8−sin−1 (sin θ / 1.5) When θ (the angle required for light distribution) is 16 °, ε = 31.2 ° That is, the inclination angle ε of the wedge-shaped prism 231 is set to 31.2 °.
In this case, all light rays having an incident angle smaller than 16 ° pass through the surface α of the prism 231, and all light rays having an incident angle of 16 ° or more are totally reflected by the surface α of the prism 231.

In consideration of application to a wide-angle lens, the light distribution angle θ required in the longitudinal direction is, for example, f =
About 36 ° for 28 mm lens, 4 for f = 24 mm
Since θ is about 0 °, ε = 18.7 ° when θ = 36 ° ε = 16.4 ° when θ = 40 ° Therefore, the inclination angle ε in the case of using a wedge-shaped prism for the camera illumination device It is considered that the values (when n '= 1.5) are generally in the range of ε ≧ 15 ° and ε ≦ 40 °.

FIGS. 1 and 2 are cross-sectional views of a lighting device according to an embodiment of the present invention. FIG. 1 is a cross-sectional view showing a light ray path when light rays emitted from a light emitting point O at the center of the light emitting portion 22a of the flash light emitting tube 22 to the left and right of the irradiation center axis 24 enter the prism 23. FIG. FIG. 4 is a cross-sectional view showing a light ray path when light rays emitted from a light emitting point A at a position off the center of a light emitting portion 22a of the light emitting tube 22 to the right and left of an irradiation axis 25 enter a prism 23.

In FIGS. 1 and 2, the lighting device 20 comprises:
A reflector 21 whose inner surface is formed as a reflecting surface as a reflecting member, a flash light emitting tube 22 as a light source disposed on the inner surface on the back side 21a of the reflector 21, and at least one prism (4 in FIG. And a prism unit 23 composed of two prisms.

The reflector 21 is formed of a reflective material such as brilliant aluminum, and has an umbrella-like shape that opens radially from the back side 21a to the opening side. The reflector opening through which light is emitted has a substantially rectangular shape. Is formed. Further, a through hole 21b is formed in the reflector back side 21a, and the flash luminous tube 22 is made to penetrate through the through hole 21b so that the flash luminous tube 22 can be arranged on the inner surface of the back side 21a of the reflector 21. Arc tube 22 of reflector 21
The diameter of the side opening is formed larger than the length (light emission range) of the light emitting portion 22a of the flash arc tube 22.

The flash light emitting tube 22 has a light emitting portion 22a in which a gas such as xenon is sealed in a cylindrically long transparent glass tube.
And electrode lead portions 22 provided at both ends of the light emitting portion 22a.
and a discharge tube such as a xenon tube having b and 22c.

The prism unit 23 has four prisms 23a to 23d close to each other across an air layer (this air layer forms transmission / total reflection surfaces α and β) as shown in FIGS. Placed and parallel plate-like (plane μ
And the surface ρ are parallel), and these four prisms 23 a to 23 d are arranged so as to fit inside the reflector 21. Each prism is formed of a translucent material such as glass or synthetic resin.

The prism unit 23 includes a flash arc tube 22
And an incident surface μ on which light diverging from the flash tube 22 is incident, and first and first light transmitting and totally reflecting light passing through the incident surface μ according to the incident angle θ. Second
And the exit surface ρ for finally emitting light transmitted and totally reflected by the first and second transmission / total reflection surfaces α and β to the front. ing.

The first and second transmission / total reflection surfaces α and β can transmit or totally reflect the light passing through the incident surface μ in accordance with the incident angle θ, and transmit the transmitted light forward. The flash light emission tube 22 is provided over substantially the entire area in the longitudinal direction so that the light that is totally reflected is directed laterally. The first and second transmission / total reflection surfaces α and β are formed substantially line-symmetrically in the longitudinal direction of the flash arc tube 22 with respect to the irradiation center axis 24 of the illumination device 20, and the first and second transmission / total reflection surfaces α and β are formed. The total reflection surfaces α and β intersect each other near the irradiation center axis 24.

Next, the operation of the present embodiment will be described with reference to FIGS. As shown in FIG. 1, a light beam emitted at a small angle of not more than .theta.1 with respect to the irradiation center axis 24 enters the prism unit 23, passes through the surfaces .alpha.
The light is emitted from the prism unit 23 at the following small angle. Here, θ1 is an incident angle that is slightly smaller than the incident angle corresponding to the critical angle of total reflection on the surface α and the surface β, and when the lighting device is mounted on a camera, θ1 corresponds to the shooting angle of view. This is the light distribution angle required to illuminate the shooting range.

An angle larger than θ1 with respect to the irradiation center axis 24 (for example, θ2 larger than the critical angle of total reflection in FIG. 1)
The light rays emitted to the left and right sides are totally reflected by the surface α in a range rightward from the center. In the range on the left side with respect to the irradiation center axis 24, the light is totally reflected on the surface β. Light rays totally reflected by the surfaces α and β are further reflected by the inner surface of the reflector 21. (Note that, depending on the angle of the light beam, the light may be totally reflected by the side surfaces γ and δ of the prism.) The reflector reflected light passes through the prisms 23b, 23c and 23d and is smaller than the above-mentioned angle θ1 to the outside from the exit surface ρ. It is also possible to emit at an angle (that is, within the shooting light distribution angle).

As shown in FIG. 2, even at the light emitting point A shifted from the center of the flash light emitting tube 22, the exit angle of the light beam having a small angle of not more than θ1 is the same as that in FIG.

The light beams emitted at angles θ2 and θ3 larger than θ1 are totally reflected on the surfaces α and β, guided to the reflector 21 side, and further reflected on the inner surface of the reflector 21.
(However, there are some rays such as θ2 emitted to the right of the irradiation axis 25 at the point A in FIG. 2 that are totally reflected twice from the surface β and the surface α and are not guided to the reflector 21 side.) The reflected light from the reflector can be transmitted through the prism 23b or 23c and the prism 23d and emitted outside from the exit surface ρ at a small angle of θ1 or less.

FIG. 7 is an exploded perspective view of the four prisms 23a to 23d constituting the prism unit 23. FIG. 8 shows the prisms 23a to 23 shown in FIG.
FIG. 9 is a cross-sectional view illustrating an actual combination state of prisms 23a to 23d in a case where the illumination device 20 is configured by combining d with a reflector 21.

In FIG. 8, the prisms 23a to 23a shown in FIG.
A prism unit 23 having a generally parallel plate shape is formed by arranging 23d close to each other across the first and second air layers 27 and 28, and combining the prism unit 23 with the reflector 21 and the flash tube 22. , Lighting device 20
Is composed.

The first air layer 27 is formed with a substantially uniform width l1 so as to form a first transmission / total reflection surface α. The second air layer 28 extends in the longitudinal direction of the flash tube 22 with respect to the irradiation center axis 24 of the illumination device 20 so as to form a second transmission / total reflection surface β.
And a substantially uniform width l2 at a position substantially symmetrical with the line. The width l1 and the width l2 are usually set to be equal. The first air layer 27 and the second air layer 28 are
They intersect near the irradiation center axis 24.

The prism unit 2 composed of the prisms 23a to 23d shown in FIGS. 1, 2, 7, and 8 is used.
In No. 3, a parallel plate prism unit is formed by further combining the prism 23d with the combination of the three prisms 23a to 23c. When the irradiation angle (incident angle) θ does not cause total reflection at β, the light can be emitted from the emission surface ρ at the same emission angle θ.

In this embodiment, three prisms 23a
23c form a line of a cross that can be transmitted / totally reflected by the surfaces α and β, so that basically, the existence of the surfaces α and β that can transmit and / or totally reflect the cross efficiently collects. The concept of light is established, and if the transmission / total reflection surfaces α and β exist, the prism 23d may be omitted. Actually, among the prisms 23a to 23d in the prism unit 23, the configuration in which the prism 23d is omitted only slightly changes the emission angle emitted to the outside of the reflector 21. Therefore, the configuration in which the prism 23d is omitted may be employed. it can. Alternatively, even if the configuration is such that the prism 23d is omitted, it is possible to efficiently collect light in a target range by setting the inclination angles of the surfaces α and β.

A prism unit 2 composed of the prisms 23a to 23d shown in FIGS. 1, 2, 7 and 8.
In FIG. 8, among the prisms 23a to 23d constituting the prism unit 23, the prisms 23a to 23c are
Without combining the air layers as shown in
The three prisms 23a to 23c are closely attached to each other or 3
1, 2, 7, and 8 are substantially the same as those shown in FIGS. 1, 2, 7, and 8 when the prism 23d is combined with the integrated one with the air layer interposed therebetween. Function can be obtained. As described above, light rays totally reflected twice on the plane β and the plane α, such as the incident angle θ2 emitted to the right of the irradiation axis 25 at the point A in FIG. 2, are wasted without being guided to the reflector 21 side. However, since the three prisms 23a to 23c are in close contact or integrated with each other, the surfaces α and β from the arc tube side from the cross point are eliminated, so that there is a light beam that is totally reflected twice from the surface β and the surface α. Instead, the light is emitted forward, so that the light rays can be used effectively.

FIGS. 9 and 10 show ray tracing diagrams corresponding to the lighting apparatus of the embodiment shown in FIGS. 1 and 2. FIG. However, FIGS. 9 and 10 show an example in which the emission side of the prisms 23b, 23c, and 23d in FIGS. 1 and 2 is partially cut in order to reduce the depth of the illumination device and reduce the size. I have. Thus, even when the emission side is cut by the same cut surface, the overall configuration of the prism unit 23 maintains the parallel plate shape.

FIG. 9 shows a light ray path when light rays emitted from the light emitting point O at the center of the light emitting portion of the flash light emitting tube 22 to the left and right of the irradiation center axis 24 enter the prism unit 23.

As shown in FIG. 9, the light distribution angle required to irradiate the photographing range corresponding to the photographing angle of view is, for example, 16 °, and this 16 ° is the transmission / total reflection surface α, in the prisms 23b and 23c. It is assumed that the angle is slightly smaller than the incident angle corresponding to the critical angle of β. (Note that the transmission / total reflection surface α,
The relationship between the incident angle θ of the light beam that causes total reflection (critical angle) at β and the inclination angle ε of the surfaces α and β of the wedge-shaped prism is as described with reference to FIG. However, a light beam incident on the prism unit 23 at an irradiation angle of 16 ° or less forward from the light emitting point O, or the back plate 21 of the reflector 21 from the light emitting point O
a, the light beam which is reflected forward and enters the prism unit 23 at an irradiation angle of 16 ° or less is L, L shown in FIG.
The light is illuminated all the way forward within the range of light rays denoted by L and M, M. These are rays that work effectively.

On the other hand, most of the light rays which enter the prism unit 23 at an angle equal to or larger than the angle of incidence of the light rays which are emitted forward from the light emitting point O and which cause total reflection (critical angle) at the surfaces α and β, or light emission From the point O to the back plate 21a of the reflector 21
Most of the light rays that enter the prism unit 23 at an angle equal to or larger than the angle of incidence of the light rays that are totally reflected (critical angle) on the surfaces α and β when the light beams are reflected forward on the surfaces α and β as shown in FIG. , And is guided to the inner surface (reflecting surface) of the reflector 21, reflected again by the reflecting surface, and
3a, 23b, 23c, 23d
The light exits from the surface ρ of d and the exit surfaces ρ1 ′ and ρ2 ′ of the prisms 23b and 23c flush with the surface ρ. At this time, the emission angles emitted forward from the surfaces ρ, ρ1 ′, ρ2 ′ are 3.5 °, 4.5 °, 10.4 °, 15.4 ° as shown in the figure.
The light distribution angle required to irradiate the photographing range is smaller than 16 °. These are rays that work effectively.

Further, among the light rays incident on the prism unit 23 at an angle equal to or larger than the angle of incidence of the light rays irradiated forward from the light emitting point O at the planes α and β, the rays causing total reflection (critical angle). Reflector 2 from a part or emission point O
Only a part of the light rays that enter the prism unit 23 at an angle equal to or greater than the angle of incidence of the light rays that are reflected forward on the back plate 21a of the first unit 21 and that cause total reflection (critical angle) at the surfaces α and β are shown in the figure. The prism 23 b and 23 c pass through the prisms 23 b and 23 c without being totally reflected on the surfaces α and β as shown in FIG.
b, 23c, the outgoing surfaces ρ1 ′, ρ2 ′ flush with the outgoing surface ρ.
The light is emitted at a considerably large angle such as 50 ° or 70 ° (a large emission angle that does not effectively work to illuminate the photographing range).

FIG. 10 shows the same illuminating device as that shown in FIG. The light ray path when entering is shown.

As shown in FIG. 10, a light beam which enters the prism unit 23 at an irradiation angle of 16 ° or less from the light emitting point A forward, or is reflected forward from the light emitting point A upon hitting the back plate 21a of the reflector 21. Light rays incident on the prism unit 23 at an irradiation angle of 16 ° or less are all irradiated forward within the range of light rays indicated by L, L and M, M in the drawing. These are rays that work effectively.

On the other hand, most of the light rays which enter the prism unit 23 at an angle equal to or larger than the angle of incidence of the light rays which irradiate forward from the light emitting point A at angles α or more that cause total reflection (critical angle) at the surfaces α and β, From the point A to the back plate 21a of the reflector 21
Most of the light rays that enter the prism unit 23 at an angle equal to or larger than the angle of incidence of the light rays that are totally reflected (critical angle) on the surfaces α and β when the light beams are reflected forward on the surfaces α and β as shown in FIG. , And is guided to the inner surface (reflecting surface) of the reflector 21, reflected again by the reflecting surface, and
3a, 23b, 23c, 23d
The light exits from the surface ρ of d and the exit surfaces ρ1 ′ and ρ2 ′ of the prisms 23b and 23c flush with the surface ρ. At this time, the emission angles emitted forward from the surfaces ρ, ρ1 ′, ρ2 ′ are 3.5 °, 4.5 °, 10.4 °, 15.4 as shown in the figure.
The angle is smaller than the light distribution angle of 16 ° necessary for irradiating the photographing range, such as ° and 15.7 °. These are rays that work effectively.

Furthermore, among the light rays that enter the prism unit 23 at an angle equal to or greater than the angle of incidence of the light rays that irradiate forward from the light emitting point A and that cause total reflection (critical angle) at the surfaces α and β, Reflector 2 from a part or emission point A
Only a part of the light rays that enter the prism unit 23 at an angle equal to or greater than the angle of incidence of the light rays that are reflected forward on the back plate 21a of the first unit 21 and that cause total reflection (critical angle) at the surfaces α and β are shown in the figure. The prism 23 b and 23 c pass through the prisms 23 b and 23 c without being totally reflected on the surfaces α and β as shown in FIG.
b, 23c, the outgoing surfaces ρ1 ′, ρ2 ′ flush with the outgoing surface ρ.
At an angle in the range considerably larger than 50 ° (a large emission angle that does not work effectively). In the figure, the crosses indicate that the rays are out of the imaging range (16 °) and cannot be used effectively.

As is apparent from the above description of FIGS. 9 and 10, the cross-shaped prism unit 23 in which the transmission / total reflection surfaces α and β intersect is disposed in the reflector 21. Conventional configuration (FIGS. 14 and 15)
In this case, light that has been wasted beyond the shooting range can be collected in an effective range. Therefore, when the flash tube 22 has the same constant light emission amount, more light can be collected in the effective photographing range, and light can be used effectively (efficiently). If the light emission amount for the photographing range is the same as the conventional one, a flash tube with a small emission light emission amount may be used, which is advantageous in cost.

FIG. 11 is a view for explaining a method for further downsizing the above-mentioned illumination device of the present invention. The illumination device shown in FIG. 11A is the same as that shown in FIGS. 1 and 2, and the four prisms constituting the prism unit 23 disposed in the reflector 21 have a transmission / total reflection surface α. ,
has a structure in which β intersects planarly, that is, linearly, in the vicinity of the irradiation center axis. As a method for reducing the thickness, ie, the size, of such an illuminating device, as shown in FIG.
The transmission / total reflection surfaces α and β in contact with the prism 23d in 3b and 23c remain flat, that is, linear portions α1 and β1,
Of the surfaces α and β, the surface in contact with the prism 23a is formed as a curved surface, that is, a curved portion α2, β2, so that the prism 23
The width (depth) of a is changed from d2 to d2 '(d
2 '<d2).

FIGS. 12 and 13 are sectional views showing a lighting device according to another embodiment of the present invention. 12 and 13
FIG. 11B shows an illumination device in which the method of FIG. 11B is combined with the method described in FIGS. 9 and 10 (the method of cutting the prism surface ρ) to further reduce the thickness, that is, to reduce the size. 9 and 10 are denoted by the same reference numerals.

FIG. 12 shows a light ray path when light rays emitted from the light emitting point O at the center of the light emitting portion of the flash light emitting tube 22 to the left and right of the irradiation center axis 24 enter the prism 23.

FIG. 13 shows the same illuminating device as that shown in FIG. 12, and light rays emitted from the light emitting point A at a position deviated from the center of the light emitting portion of the flash light emitting tube 22 to the right and left of the irradiation axis 25 enter the prism 23. This shows the ray path in the case of the above. Also in this case, the effective light emission angle is within 16 °.

In the embodiment shown in FIGS. 12 and 13, as in the case of FIGS. 9 and 10, a prism unit 23 having a shape where transmission / total reflection surfaces α and β intersect is disposed in a reflector 21. With this configuration, light that has been wasted beyond the shooting range in the conventional configuration (FIGS. 14 and 15) can be collected in an effective range. Therefore, when the flash tube 22 has the same constant light emission amount, more light can be collected in the effective photographing range, and light can be used effectively (efficiently). If the light emission amount for the photographing range is the same as the conventional one, a flash tube with a small emission light emission amount may be used, which is advantageous in cost. However, in the configurations of FIGS. 12 and 13, the light-collecting properties are slightly inferior to those of FIGS. 9 and 10. For example, as shown in FIG. 13, the number of invalid light beams (indicated by crosses) having an emission angle exceeding the effective range of 16 ° slightly increases as compared with the case of FIG.

In the above-described embodiment, the inclination angle ε of the transmission / total reflection surfaces α, β is determined by the angle of view of the flash tube 22 according to the angle of view of the photographing lens used in the camera as described with reference to FIG. It is preferable that the angle is set in the range of 15 ° to 40 ° with respect to the longitudinal direction.

[Appendix] (Appendix 1) In an illuminating device for irradiating forward the divergent light from a flash tube having a long cylindrical shape, it is disposed in front of the flash tube and extends in the longitudinal direction of the flash tube. The light emitted from the flash arc tube is transmitted at an angle smaller than a predetermined angle with respect to the irradiation center axis of the illumination device and is emitted forward, and the light emitted from the flash arc tube is emitted at a predetermined upper angle with respect to the irradiation center axis of the illumination device. A first light emitting tube is provided over substantially the entire area in the longitudinal direction of the flash arc tube so that light emitted from the flash arc tube is totally reflected and directed to the side at an angle larger than the angle.
A first prism having a transmissive / total reflective surface, and a first prism disposed in front of the flash arc tube at a predetermined angle above an irradiation center axis of the illumination device in a longitudinal direction of the flash arc tube. The light emitted from the flash arc tube is transmitted at a small angle and emitted forward, and the light emitted from the flash arc tube at an angle larger than an upper predetermined angle with respect to the irradiation center axis of the illumination device. And a second prism having a second transmission / total reflection surface provided over substantially the entire area in the longitudinal direction of the flash tube so that the light is totally reflected and directed to the side. Lighting equipment.

(Additional Item 2) In the additional item 1, it is characterized in that a reflecting member is provided for reflecting the light totally reflected sideways by the transmission / total reflection surface to the front.

(Additional Item 3) In the additional item 1, the first item
And the second prism is formed such that the predetermined angle is substantially equal to an angle of an irradiation range required in the lighting device.

(Additional Item 4) In a lighting device for irradiating forward the divergent light from a flash lamp having a long cylindrical shape, light radiated from the flash tube is disposed in front of the flash tube. Incident surface to be incident, light that has passed through the incident surface can be transmitted or totally reflected according to the incident angle,
The transmission / total reflection surface and the transmission / total reflection surface provided over substantially the entire area in the longitudinal direction of the flash arc tube so that the transmitted light is emitted forward and the totally reflected light is directed to the side. A prism unit having an exit surface through which the transmitted and totally reflected light finally exits forward, and forwardly directing the light, which has been totally reflected laterally by the transmission / total reflection surface, toward the exit surface. A lighting device, comprising: a reflecting member that reflects light.

(Additional Item 5) In the additional item 4, the incident surface and the exit surface of the prism unit are formed substantially parallel to a longitudinal direction of the flash tube.

(Additional Item 6) In the additional item 5, the first transmission / total reflection surface of the prism unit is substantially line-symmetric with respect to the irradiation center axis of the illumination device in the longitudinal direction of the flash arc tube. The transmission / total reflection surface and the second transmission / total reflection surface are formed, and the first transmission / total reflection surface and the second transmission / total reflection surface intersect in the vicinity of the irradiation center axis. It is characterized by the following.

(Additional Item 7) In the additional item 6, the prism unit may include a first air layer formed with a substantially uniform width so as to form the first transmission / total reflection surface; In the longitudinal direction of the flash arc tube with respect to the illumination center axis of the illumination device, so as to constitute a second transmission / total reflection surface,
A second air layer formed with a substantially uniform width at a position substantially symmetrical with the first air layer, wherein the first air layer and the second air layer are illuminated by the irradiation; It intersects near the central axis.

(Supplementary Item 8) In an illumination device for irradiating forward the divergent light from a flash lamp having a long cylindrical shape, the luminous device is disposed in front of the flash tube and emits light diverged from the flash tube. It can be transmitted or totally reflected according to the incident angle, emits the transmitted light forward, and directs the totally reflected light to the side so as to have a predetermined inclination with respect to the longitudinal direction of the flash arc tube. And a prism having the transmission / total reflection surface provided over substantially the entire area in the longitudinal direction of the flash arc tube.

(Additional Item 9) In the additional item 8, the predetermined inclination of the transmission / total reflection surface is not less than 15 degrees and not more than 40 degrees with respect to the longitudinal direction of the flash arc tube.

(Supplementary note 10) In Supplementary note 8, the transmission / total reflection surface is a first transmission / total reflection that is substantially line-symmetric with respect to an irradiation center axis of the illumination device in a longitudinal direction of the flash arc tube. Surface, and a second transmission / total reflection surface. The first transmission / total reflection surface and the second transmission / total reflection surface intersect in the vicinity of the irradiation center axis, and the first and the second transmission / total reflection surfaces intersect with each other. The second predetermined inclination of the transmission / total reflection surface is not less than 15 degrees and not more than 40 degrees with respect to the longitudinal direction of the flash tube.

[0079]

As described above, according to the lighting device of the present invention, in a lighting device requiring a relatively narrow light distribution,
It is possible to converge light more efficiently on the subject side.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a lighting device according to an embodiment of the present invention, in which a light emitting point is located at the center of a flash arc tube.

FIG. 2 is a cross-sectional view showing the lighting device according to the embodiment of FIG. 1, in which a light emitting point is other than the center of a flash arc tube.

FIG. 3 is a cross-sectional view showing a concept of guiding a light beam to a reflector using total reflection of a prism, and showing a case of a light beam emitted from a central light emitting point of a flash tube.

FIG. 4 is a cross-sectional view showing a concept of guiding a light beam to a reflector using total reflection of a prism and showing a case of a light beam emitted from a light emitting point other than the center of a flash arc tube.

FIG. 5 is a cross-sectional view showing a concept of guiding a light beam to a reflector using total reflection of a prism, and showing a case of a light beam emitted in a direction opposite to that of FIG. 3 from a light emitting point at the center of a flash tube.

FIG. 6 is an explanatory diagram showing a relationship between a reflection surface ε of a prism and an angle θ of a light source.

FIG. 7 is an exploded perspective view of a cross prism unit according to the embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a schematic configuration in a use state in which the disassembled prisms of FIG. 7 are combined in a cross shape.

FIG. 9 is a diagram showing ray tracing corresponding to the lighting apparatus of the embodiment shown in FIGS. 1 and 2, wherein the ray tracing is in the case where the light emitting point is at the center of the flash arc tube.

FIG. 10 is a diagram showing ray tracing when the light emitting point is other than the center of the flash tube in the lighting device of FIG. 9;

FIG. 11 is a cross-sectional view illustrating a method for reducing the size of a lighting device.

FIG. 12 is a ray tracing diagram in the case of a lighting device according to another embodiment of the present invention, in which a light emitting point is located at the center of a flash arc tube.

FIG. 13 is a ray tracing diagram in the lighting device according to the embodiment of FIG. 12, in which the light emitting point is other than the center of the flash arc tube.

FIG. 14 is a ray tracing diagram of a conventional illumination device for a narrow light distribution angle, in which a light emitting point is located at the center of a flash arc tube.

FIG. 15 is a ray tracing diagram of the lighting device according to the embodiment of FIG. 14, in a case where the light emitting point is other than the center of the flash arc tube.

[Explanation of symbols]

 Reference Signs List 20 lighting device 21 reflector (reflecting member) 21a back side of reflector 22 flash tube 23 prism unit 23a, 23b, 23c, 23d prism α, β transmission / total reflection surface

[Procedure amendment]

[Submission Date] September 18, 2001 (2001.9.1)
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

FIG. 14 shows a number of light beams emitted from the center point O of the light emitting portion of the flash arc tube 12 at different angles. FIG. 15 shows the center point O of the light emitting portion of the flash arc tube 12.
The figure shows a number of light rays emitted at different angles from a light emitting point A deviated from the above. While there is a light beam emitted from each light emitting point directly to the outside through the inside of the reflector 11, there is a light beam reflected on the inner surface of the reflector 11 and emitted to the outside. There are rays. Light rays traveling from each light emitting point toward the reflector back side 11a are reflected by the inner surface of the reflector back side 11a, and then pass through the inside of the reflector 11 as they are to form the aperture 11a.
and the light emitted from the b, and the light emitted from the opening 11b after being further reflected by the inner surface of the reflector 11, the reflector 11 and the flash light emitting tube 12 without reflection by the inner surface of the re off <br/> reflector 11 There is a light ray that is emitted to the outside from the gap between the two sides (the light ray does not effectively act on the subject side).

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

In FIG. 6, the refractive index of the prism is n ',
Assuming that the refractive index of the atmosphere is n, n sin θ = n ′ sin θ ′ i is a critical angle at which total reflection occurs, and i = sin ⁻¹ (n / n ′). Therefore, from FIG. 6, ε = i−θ ′ = sin ⁻¹ ( n / n ′) − sin ⁻¹ (nsin θ /
n ′) For example, when a prism with n ′ = 1.5 is used, ε = 41.8− sin ⁻¹ (sin θ / 1.5) When θ (the angle required for light distribution) is 16 °, ε = 31.2. ° That is, the inclination angle ε of the wedge-shaped prism 231 is set to 31.2 °.
In this case, all light rays having an incident angle smaller than 16 ° pass through the surface α of the prism 231, and all light rays having an incident angle of 16 ° or more are totally reflected by the surface α of the prism 231.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

The reflector 21 is formed of a reflective material such as brilliant aluminum, and has an umbrella shape that opens radially from the back side 21a to the opening side. The reflector opening from which light is emitted has a substantially rectangular shape. Is formed. Further, a through hole 21b is formed in the reflector back side 21a, and the flash luminous tube 22 is made to penetrate the through hole 21b so that the flash luminous tube 22 can be arranged on the inner surface of the back side 21a of the reflector 21. Arc tube 22 of reflector 21
Diameter size of the side openings, the length of the light emitting portion 22a of the flash light emitting tube 22 is formed larger than the (emission range).

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction contents]

In FIG. 8, the prisms 23a to 23a shown in FIG.
23d is disposed close to the first and second minute air layers 27 and 28 to form a parallel plate prism unit 23 as a whole. The prism unit 23 is formed by the reflector 21 and the flash tube 22. To form the lighting device 20.

Claims (3)

[Claims] An illumination device for irradiating divergent light from a light source forward, wherein an incident surface on which the light from the light source is incident, and light passing through the incident surface can be transmitted or totally reflected according to an incident angle. A prism having a transmission / total reflection surface that emits transmitted light forward and directs the totally reflected light to the side; and light that is totally reflected laterally by the transmission / total reflection surface. And a reflecting member for reflecting light forward. 2. An illuminating device for irradiating divergent light from a flash lamp having a long cylindrical shape to the front, wherein the illuminating device is disposed in front of the flash luminous tube and emits light diverging from the flash luminous tube at an angle of incidence. The flashlight can be transmitted or totally reflected in response to the transmitted light, and the transmitted light is emitted forward, and the totally reflected light is directed to the side. / The total reflection surface
A lighting device, comprising: a prism having the same. 3. The transmission / total reflection surface includes a first transmission / total reflection surface and a second transmission / total reflection surface which are substantially line-symmetric with respect to an irradiation center axis of the illumination device in a longitudinal direction of the flash arc tube. 3. The lighting device according to claim 2, wherein the illumination device is formed by a reflection surface, and the first and second transmission / total reflection surfaces intersect each other near the irradiation center axis.