JP2010097074A - Stroboscope device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stroboscope device that achieve strobe light distribution without irregularity in light even if area of a light emitting part is made small by raising a light condensing rate. <P>SOLUTION: In the stroboscope device 10 including a light source 12 emitting strobe light, and a reflector 11 reflecting the strobe light from the light source 12 to a subject, a composite front reflection surface 13 is provided on an inner surface of the reflector 11. The composite front reflection surface 13 comprises an elliptical reflection surface part 13a, a back reflection surface part 13b, and a connection reflection surface part 13c. The connection reflection surface part 13c smoothly connects the elliptical reflection surface part 13a and the back reflection surface part 13b, and is formed in shape to reflect light emitted from a center axis of the light source to the side of a radiation direction of the stroboscope device from the center axis of the light source. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a strobe device, and more particularly, to a strobe device for irradiating a subject with light emitted from a flash tube as auxiliary light for photographing.

  As is generally known, a conventional strobe device is used at the same time as a camera, a digital photographing device, or the like as an auxiliary light source device when taking a picture at night or the like. For example, a strobe device shown in FIG. 6 is known as a strobe device built in a camera.

  FIG. 6 is a perspective view of a conventional strobe device. A strobe device 101 shown in FIG. 6 is a light source 102 composed of a xenon tube or the like that is long in the width direction (X-axis direction), and a strobe light emitted from the light source 102. A reflector 103 that reflects toward a subject and a rectangular plate-like lens (not shown) that covers the front surface (light emitting surface) of the reflector 103 are provided.

  The reflector 103 is formed by bending a metal material. Specifically, it has a front reflecting surface (vertical wall) 103A having a parabolic curved surface and flat side reflecting surfaces (horizontal walls) 103B formed at both ends thereof, and strobe light emitted from the light source 102 is Mostly, the reflection direction (light quantity distribution) is primarily controlled by the front reflecting surface (vertical wall) 103A and the side reflecting surface (horizontal wall) 103B of the reflector 103. Then, the reflected light primarily controlled by the reflector 103 is secondarily controlled (light distribution) by a lens (not shown) that has been cut and irradiated with a shooting angle of view as shown in FIG. Suitable light quantity and light distribution characteristics can be obtained.

  Patent Document 1 shows this type of strobe device. In this document, an insertion port is provided in a pair of side walls of a reflector made of a metal material, and a rod-shaped discharge tube is inserted and fixed from the insertion port. Further, a part of the reflector is formed with a back part that is concavely formed so as to wrap the discharge tube from the back side, and has a shape that expands toward the front face of the reflector (light emitting surface).

The vertical cross-sectional shape of the reflector is, in most cases, a reflecting surface composed of a linear portion that expands toward the front surface (light emitting surface) of the reflector and a curved portion near the light source. An elliptical back reflecting surface has also been proposed.
JP 2001-228515 A

  By the way, recent strobe devices are required to have a thin depth and a small area of the light exit surface (front opening area). Reducing the depth is directly linked to reducing the light flux captured by the reflector, leading to a decrease in luminous intensity. Reducing the area of the light exit surface reduces the shooting angle of view and makes it difficult to obtain the necessary light distribution.

  FIG. 8 is an explanatory diagram showing the light emission direction in the strobe device. In general, since the strobe device has a horizontally long rectangle like the strobe device 101 shown in FIG. 6, the vertical direction with respect to the light irradiation direction in the light distribution control by the reflector is relatively easy to control, but the left and right The direction (width direction) is difficult, and a Fresnel lens or the like whose lens has been cut is used. However, in reality, the effect is not as good as the light distribution control in the vertical direction. As shown in the explanatory diagram of FIG. 8, the parallel light La of the strobe light emitted from the light source 102 can be directed toward the subject (focal point) by the lens 104, but the lens L is used for the other light Lb. In 104, it is difficult to control and it cannot be directed to the subject (focus). Further, in order to obtain a desired light distribution by reducing the depth of the strobe device and reducing the area of the light emitting surface, a more complicated cut is required for the lens 104, which is preferable from the viewpoint of cost and design. Absent. For example, in order to control the light toward the left and right ends of the strobe reflection surface, it is necessary to increase the cut angle of the lens cut, but the cut surface becomes steep and it is difficult to manufacture the lens. In addition, it is difficult to make a cut for controlling the light toward the upper and lower end portions of the strobe reflection surface to be compatible with the light control in the left-right direction.

In view of this, the present inventor has studied a strobe device in which the longitudinal sectional shape of the reflector is an elliptical reflecting surface.
FIG. 9 is a schematic cross-sectional view for explaining the positional relationship between the elliptical reflecting surface of the reflector and the light source in the strobe device for preliminary examination conducted by the inventor. As shown in FIG. 9, the reflector 203 includes an elliptical reflecting surface 203 a having two focal points and a back reflector 203 b that covers the light source 202. A first focal point of the elliptical reflecting surface 203a is located at the center of the light source 202, and a part of an ellipse having a second focal point at a position 5 m ahead where the subject is located is used. The back reflector 203b is a partial arc of a concentric circle in which the center position of the light source 202 is matched and the diameter is slightly increased, and has a shape combined with the ellipse.

  FIG. 10 is a diagram showing the light distribution of the strobe device in this preliminary study as an intensity distribution in the longitudinal section direction. Regarding the vertical light distribution (vertical cross section light distribution) of the strobe device, it is shown that it is effective to collect light near the center by using the elliptical reflecting surface 203a in order to increase the luminous intensity near the center. Yes. However, as can be seen from FIG. 10, the pattern of the shape in which the position of the central luminous intensity corresponding to the front position C of the strobe device is recessed is shown. This light distribution newly causes unevenness of light.

  The present invention has been made in view of the above problems, and in a strobe device using a tube-shaped light source, the vertical light collection rate of the strobe device is increased to increase the central luminous intensity and the intensity distribution of the light distribution. In the present invention, a strobe device provided with a reflective surface that is less likely to cause unevenness of light in the vertical direction without forming a pattern having a concave center light intensity position is provided.

In order to achieve the above object, the invention described in claim 1 is a strobe device comprising a tubular light source and a reflector having an opening in the irradiation direction of the strobe device, wherein the reflector is orthogonal to the tube central axis of the light source. The cross-sectional shape is composed of the elliptical reflecting surface portion on the opening side and the back reflecting surface portion on the light source side via the connecting reflecting surface, and the back reflecting surface is concentric with the light source central axis and larger than the light source. Radius and the central angle of the arc is greater than 180 degrees,
The ellipsoidal reflecting surface uses the first focal position of the ellipse as a light source, the second focal position serves as the center position in the irradiation direction of the strobe device, and the connecting reflecting surface smoothens the elliptical reflecting surface and the back reflecting surface. The light source is connected and formed in a shape that reflects light emitted from the light source central axis toward the irradiation direction side of the strobe device from the light source central axis.

According to a second aspect of the present invention, in the first aspect of the present invention, the central angle of the arc of the back reflecting surface is greater than 180 degrees and smaller than 260 degrees, and the connection reflecting surface is from the light source central axis. The emitted light is shaped to reflect toward the elliptical reflecting surface.
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  According to the first aspect of the invention, of the strobe light emitted from the light source, the light incident on the elliptical reflecting surface is condensed at the central portion in the vertical direction in the light distribution characteristic of the strobe device, and near the center. This contributes to an increase in the amount of light. The light incident on the connection reflecting surface is reflected toward the irradiation direction of the strobe device or toward the elliptical reflecting surface, re-reflected by the elliptical reflecting surface, and then proceeds toward the irradiation direction. Thereby, the light collection rate in the vertical direction can be increased, and the strobe light distribution in which the uneven light distribution in which the light distribution pattern in the upper limit direction in the central portion is uniform is reduced as compared with the case where there is no connection reflection surface is realized.

  According to the second aspect of the invention, in the vertical direction, in other words, in the direction orthogonal to the light source central axis, most of the light emitted from the light source toward the back side can be extracted forward in the irradiation direction. . Moreover, the utilization efficiency of strobe light can be increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about the same structure as the structure demonstrated by the background art mentioned above, a part of the description is abbreviate | omitted.

  1 and 2 show a strobe device according to the present invention. FIG. 1 is a perspective view and FIG. 2 is a side view. The strobe device 10 includes a light source 12 formed of a xenon tube or the like that is long in the width direction (x direction), and a reflector 11 provided with a reflection surface 13 that reflects the strobe light from the light source 12 toward a subject to be irradiated. And a rectangular plate-shaped lens 14 covering the front surface (light emitting surface) of the reflector 11. In the orthogonal coordinate system when the origin is the center of a rectangular strobe device, the y direction is the light irradiation direction of the strobe device, and the x direction is the width direction of the strobe device (the length direction of the tubular light source 12). , The z direction corresponds to the upward direction. Also, the strobe device is built in, for example, at a position near the finder of the digital camera so that the light source is almost horizontal in use.

  The light source 12 uses a flash light source such as a xenon flash lamp generally called a xenon lamp. Xenon gas is sealed in a cylindrical glass tube 12a having an inner diameter of several millimeters Φ, electrodes are provided at both ends and sealed, and electrode rods 12b such as tungsten are drawn out from both ends, not shown. Connected to external lighting circuit.

  The reflector 11 is provided so as to cover more than half of the outer diameter of the light source 12, and the light irradiation direction side is an opening 11c. A circular light source insertion port 11b is provided on the back side of the side surface 11a of the reflector 11. The tubular light source 12 is inserted from the insertion port 11b and the light emitting part (between both end electrodes) of the light source 12 is stored. The mounting and fixing are performed at a predetermined position. Further, a reflecting surface 13 which will be described in detail later is formed on the inner surface of the reflector 11. The reflective surface 13 can also be made of the material of the reflector 11 itself. When a reflector is formed using a high reflectance member, the manufacturing cost can be reduced. In order to further increase the reflectance, a high reflectance material layer such as silver may be provided on the surface by means of vapor deposition, sputtering, plating, coating, or the like.

  Such a reflector 11 is preferably formed by cutting and bending a metal plate such as an aluminum alloy into a predetermined shape or rolling from a thick plate. When the reflector 11 is made of a conductive material such as a metal material, both ends of the xenon lamp are exposed to the outside of the reflector. This is because a high electric field is applied to the electrode rod 12b to turn on the xenon lamp. When the tubular light source 12 that does not require a high voltage is used, or when the reflector 11 made of a non-conductive resin material is used, it is not necessary to expose both ends of the light source 12 to the outside.

  The lens 14 is made of a translucent resin such as acrylic or polycarbonate, and a lens cut is formed on the surface thereof. The lens cut is, for example, a Fresnel shape, and is formed in a shape that controls light distribution in the left-right direction (x direction). The lens 14 has a short side that is longer than 1 and 3 times longer than the tube diameter of the cylindrical light source 2 so that the area of the front surface is reduced, and a small size that emits light from the front surface with a small area. It is supposed to be.

  FIG. 3 illustrates the front reflecting surface of the reflecting surface 13 described above. In the longitudinal section of the reflector 11, that is, the section cut along the zy plane perpendicular to the central axis of the tubular light source 12, the reflecting surface, the light source, and It is drawing for demonstrating the relationship of these. The reflection surface 13 is expanded toward the light irradiation direction (y direction) side, and includes an elliptical reflection surface portion 13a on the opening 11c side, a back reflection surface portion 13b on the light source 12 side, and the elliptical reflection surface portion 13a. It has the connection reflective surface 13c provided between the back reflective surface parts 13b.

The reflecting surface 13 will be described along the design procedure. First, the back reflection surface portion 13b and the elliptical reflection surface portion 13a are designed.
The back reflecting surface portion 13b defines a concentric circle 32 indicated by a dotted line centered on the center of the concentric circle with the light source 12, that is, the tube axis position O and having a radius r32 larger than the outer peripheral radius r12 of the light source 12. At this time, r32 is in a range from r12 × 1.02 to r12 × 1.5. If the thickness is smaller than this, unevenness of light tends to occur unless the manufacturing and assembly accuracy of the reflector 11 and the light source 12 are increased, and if it is larger than this, the merit of downsizing is reduced.
The elliptical reflection surface portion 13a is designed. The elliptical reflecting surface portion 13a uses a partial region of an ellipse 33 indicated by a dotted line. The ellipse 33 is an ellipse whose first focal point F1 is the tube axis position O and whose other second focal point is the center of the irradiation direction, that is, the center of the field of view shown in FIG.

Next, the positions of the intersections P1 and P2 between the concentric circle 32 and the ellipse 33 are adjusted so that the central angle θ of the concentric fan P1-O-P2 is greater than 180 degrees and smaller than 260 degrees. The arc of this fan becomes the back reflecting surface portion 13b. When the central angle θ is smaller than 180 degrees, the supplemental amount of light directed to the side opposite to the irradiation direction reflected by the back reflecting surface portion 13b, that is, in the −y direction is reduced, and the brightness at the central portion of the photographing field angle is reduced. On the other hand, if the angle is larger than 260 degrees, the amount of light that cannot be extracted to the outside due to the multiple reflection in the back reflecting surface portion 13b increases, and the light quantity of the entire strobe device decreases.

  Next, the connection reflection surface 13c is designed. The connection reflection surface 13c smoothly connects the elliptical reflection surface portion 13a and the back surface reflection surface portion 13b, and emits light from the tube axis position O to the irradiation direction of the strobe device (y direction) from the tube axis position O. ) Design in a shape that reflects to the side. Specifically, the design is based on the ray tracing result shown in FIG. FIG. 4 (a) shows the result of ray tracing on the reflecting surface obtained by connecting the elliptical reflecting surface portion 13a and the back reflecting surface portion 13b via the connecting reflecting surface 13c in the vicinity of the intersections P1 and P2, and FIG. This is a ray tracing result on a reflection surface that is considered, that is, a reflection surface including only an elliptical reflection surface portion 13a ′ and a back surface reflection surface portion 13b ′ at intersections P1 and P2.

  When the connection reflecting surface 13c does not exist, the light beam emitted from the tube axis position O and reflected by the back reflecting surface portion 13b in the vicinity of the intersections P1 and P2 again becomes the tube axis position as shown in FIG. Proceeding toward O, it hits the back side reflection surface part 13b on the opposite side. Therefore, there are few light ray components that are repeatedly reflected along this optical path and directed in the y direction. On the other hand, when the connection reflection surface 13c is provided, as shown in FIG. 4A, the light beam emitted from the tube axis position O and reflected by the connection reflection surface portion 13c in the vicinity of the intersections P1 and P2 Proceed toward the reflecting surface portion 13a or the opening 11c. Thereby, the light quantity which goes to a light irradiation direction increases.

The connection reflecting surface 13c is designed to perform such an action. Specifically, in the region where the central angle θ exceeds 180 degrees, more specifically, in the range exceeding +90 degrees and −90 degrees around the −y axis, the reflection direction of the light beam is on the opening 11c side. And so as to be smoothly connected to the elliptical reflecting surface portion 13a. As a result, the intersections P1 and P2 become slightly larger, and the reflector is not excessively enlarged.
Note that the light beam emitted from the actual xenon lamp cannot be regarded as a point light source at the tube axis position O as shown in FIG. 4, has a finite size, and includes a glass tube 12a. For this reason, there is also light emitted from positions other than the tube axis position O of the light source 12, but these light can also be emitted mainly toward the photographing field angle.

  The respective reflecting surface portions 13a, 13b, and 13c are designed by the above procedure, and the reflecting surface 13 is created in accordance with the design. The reflector 11 is formed so that the front reflection surface has the same cross-section cut along the yz plane, that is, the vertical cross-section. The ellipsoidal reflecting surface is not limited to the ellipse described above, and includes an ellipse-based reflecting surface obtained by substituting a part of the ellipse with another cross-sectional curve.

  Next, the operation of the strobe device 10 having the above configuration will be described.

A strobe device 10 according to the present embodiment is built in a digital camera or the like, and flashes from a light source 12 of the strobe device 10 in synchronization with an operation of a shutter button of a camera (not shown).
Most of the strobe light emitted from the light source 12 is irradiated toward the reflector 11, is reflected by the reflecting surface 13 of the reflector 11, passes through the lens 14, travels toward the subject, and part of the strobe light directly. Passing through the lens 14 toward the subject.

  FIG. 5 is a diagram showing the intensity distribution in the vertical direction of the strobe light distribution according to the present invention in comparison with the strobe light distribution in the case of the strobe device having the reflecting surface in FIG. Standardized. Reference numeral I denotes the light distribution in the case where the reflecting surface in FIG. 4B, that is, the connection reflecting surface 13c is not provided, and reference numeral J denotes the light distribution in the present invention, that is, the connection reflecting surface 13c is provided. At this time, a transparent lens without a lens cut was used as the lens 14.

  As can be seen from this figure, in the strobe device 10 according to the present invention, in the light distribution characteristics in the vertical direction (z direction), the central portion, that is, the central portion is flattened so as not to be recessed compared to the surroundings. . In the evaluation result by actual photography, the light unevenness is eliminated by the difference in the light distribution. In addition, the central luminous intensity can be relatively increased by the combination of the reflecting surfaces according to the present invention, and further, it can be flattened over a wide range of 10 degrees up and down from the center. Therefore, in actual photography, it is possible to obtain high light intensity and uniformity in the most important central portion. In addition, the light distribution characteristic in the left-right direction (x direction) was the same as the conventional one.

  With the configuration as described above, the light from the light source 12 toward the back direction and the side surface direction can also be used effectively, so that the total amount of light increases. Further, it is possible to increase the light amount and improve the uniformity of the central portion in the vertical direction (z direction) of the strobe device 10. Therefore, a strobe device in which the vertical width of the strobe device 10 is narrowed can be realized, and the degree of freedom of the design on the front side of the camera can be increased when incorporated in the camera. Further, the depth of the strobe device itself is not increased.

  The strobe device of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention, such as providing a flat surface on a part of the elliptical reflecting surface. Of course, it can be added.

1 is a perspective view of a strobe device according to the present invention. 1 is a side view of a strobe device according to the present invention. It is a fragmentary longitudinal cross-section explaining the relationship between the reflector and light source of the strobe device according to the present invention. It is a fragmentary longitudinal cross-section which shows the ray trace result with respect to the parallel ray of a strobe device. (A) is a partial vertical cross-sectional view of a strobe device according to the present invention (b) is a partial vertical cross-sectional view of a strobe device of a preliminary study of the present invention It is a figure which compares and compares the intensity distribution of strobe light distribution which concerns on this invention with the intensity distribution of preliminary examination. It is a perspective view of the conventional strobe device. It is a figure explaining the imaging | photography angle of view of a strobe device. It is a partial side sectional view of a conventional strobe device. It is a fragmentary longitudinal cross-section explaining the relationship between the reflector of the strobe device of preliminary examination, and a light source. It is a figure which shows intensity distribution of strobe light distribution of preliminary examination.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Strobe device 11 Reflector 12 Light source 13 Reflecting surface 13a Elliptic reflecting surface portion 13b Back reflecting surface portion 13c Connection reflecting surface portion 14 Lens θ Center angle of arc

Claims (2)

In a strobe device comprising a tubular light source and a reflector having an opening in the irradiation direction of the strobe device,
The reflector has a cross-sectional shape orthogonal to the tube central axis of the light source, the elliptical reflection surface portion on the opening side and the back reflection surface portion on the light source side are combined via a connection reflection surface,
The back reflecting surface is concentric with the light source central axis, has a larger radius than the light source, and a central angle of the arc is larger than 180 degrees,
The elliptical reflecting surface has a first focal position of the ellipse as a light source, a second focal position as a center position in the irradiation direction of the strobe device,
The connection reflective surface smoothly connects the elliptical reflective surface and the back reflective surface, and reflects light emitted from the light source central axis toward the irradiation direction side of the strobe device from the light source central axis. A strobe device characterized by that. The central angle of the arc of the back reflecting surface is an angle greater than 180 degrees and less than 260 degrees;
The strobe device according to claim 1, wherein the connection reflection surface is configured to reflect light emitted from the light source central axis toward the elliptical reflection surface.

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