JPH0247640A - Built-in lighting device for camera - Google Patents

Abstract

PURPOSE:To prevent a red-eye phenomenon without changing the light distribution characteristic of a light source by specifying the shape of the cross sections of 1st and 2nd reflection parts cut with a plane including the optical axis of a light beam from the light source. CONSTITUTION:A 1st reflecting surface 01 and a 2nd reflecting surface 103 are formed on the inner surface of the 1st reflection part 100 and the outer surface of the 2nd reflection part 102 respectively. The light source 105 is arranged on the position of the focal point F1 of the 1st reflection part 100 and the 1st reflection part 100 and the 2nd reflection part 102 are respectively shown as formulas I and II. In the formulas I and II, Ai>Bi (i=1 and 2). Then, L is allowed to satisfy a formula III or IV so that the position of the light source 105 or the position where light from the light source 105 is condensed may coincide with either of the focal positions of the 1st reflection part 100 and either of the focal positions of the 2nd reflection part 102 may almost coincide with the other focal position of the 1st reflection part 100. Thus, the red-eye phenomenon can be prevented from occurring without changing the light distribution characteristic.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to the built-in lighting device of a camera used when taking pictures in a dark place. Regarding the built-in lighting device of a camera.

[Prior art] Recently, cameras with built-in illumination devices have become popular.

In this type of camera, the distance between the optical axis of the photographing optical system and the light emitting part is usually shorter than in a camera equipped with an external illumination device. When taking pictures with an external camera, the so-called red-eye phenomenon, in which the pupils of a person appear red, is more likely to occur with an external camera than with a camera equipped with a lighting device.

Furthermore, cameras equipped with external lighting devices that are said to be less likely to cause red-eye phenomena require contacts to provide synchronization signals to the lighting devices. Alternatively, it is necessary to provide a device that generates a synchronization signal to be sent to the lighting device.Furthermore, external lighting devices are generally expensive, and as a countermeasure against the red-eye phenomenon, it is not preferable.

Furthermore, Japanese Patent Application Laid-Open No. 74525/1983 discloses a device that uses a built-in lighting device to take measures against the red-eye phenomenon. In this disclosed example, two mirrors are used to reflect a portion of the light to a position farther away than the built-in illumination device, thereby irradiating the subject with light from a further distance.

[Problems to be Solved by the Invention] However, in the disclosed example described above, a part of the light from the light source is reflected and irradiated onto the subject, so there is a problem that the light distribution characteristics originally possessed by the light source change. . Changes in light distribution characteristics can cause problems with uneven illumination. The present invention was made to solve this problem, and it is an object of the present invention to provide a built-in lighting device for a camera that can prevent the red-eye phenomenon without changing the light distribution characteristics of the light source.

[Means for Solving the Problems] A built-in lighting device for a camera according to the present invention includes a light source, a first reflecting section that reflects light from the light source in a direction away from a photographic lens, and a first reflecting section that reflects light from the light source in a direction away from the photographic lens. and a second reflecting section that reflects light from the section toward the subject.

[Function 1] The built-in lighting device of this camera includes a first reflecting section and a second reflecting section, so that the optical axis of the light irradiated from the second reflecting section to the subject is aligned with the optical axis of the photographic lens. 6, the direction of the light irradiated from the second reflecting section is matched with the direction of the light emitted from the light source, so that the light from the second reflecting section is moved away from the second reflecting section without changing the light distribution characteristics of the light source. can be irradiated.

[Example] A first example of a built-in lighting device for a camera according to the present invention is a first example.
As shown in the figure. The built-in illumination device 1 of the camera includes a first reflecting section 4 and a second reflecting section 4, each having a shape obtained by cutting a part of a spheroid.
It is equipped with a reflecting section 10. The first reflecting section 4 has a first reflecting surface 2 formed on its inner surface, and the second reflecting section 10 has a long axis aligned with the long axis of the first reflecting section 4 and a second reflecting surface 2 formed on its inner surface. A surface 8 is formed. The long axes of the first reflecting section 4 and the second reflecting section 10 are aligned with the X axis.

The first reflecting section 4 has a focal point F1, a focal point F, -.

The second reflecting section 10 has a focal point F2 and a focal point F2.

The first reflecting section 4 and the second reflecting section 10 are arranged such that the focal point Fl- and the focal point F2 are aligned. A point light source 6 is arranged at a focal point F1 inside the first reflecting section 4.

First, this invention will be explained in detail. In FIGS. 5 and 6, a cross section passing through the long axis of the spheroid is shown to simplify the explanation. In FIG. 5, focus F1 and focus F
A first reflecting section 100 having a focal point F2 and a second reflecting section 102 having a focal point F2- are shown, and their long axes are aligned with each other. Their long axes are aligned with the X axis. In addition, the first reflecting section 100 and the second reflecting section 100
The reflecting section 102 is arranged such that the focal point Fl- and the focal point F2- are aligned with each other. A first reflective surface 101 is formed on the inner surface of the first reflective section 100, and a first reflective surface 101 is formed on the inner surface of the first reflective section 100.
A second reflective surface 103 is formed on the outer surface of 2. 1st
A light source 105 is arranged at the focal point F1 of the reflecting section 100. First reflecting section 10o and second reflecting section 102
is expressed by the following formula.

1st reflective surface
1 However, the respective focal positions of the first reflecting section 100 and the second reflecting section 102, where AI > B, (+ = t, 2), are expressed as Fl, Fl-1F2. Assuming F2-,
It is shown below.

Fl =-(Al” Fs = (A1 ” F2=L-(A2 F2 − =L+ (A2 Here, Fl − and F2 −B1・)′/″ −Bl・)′/= ・−82・)A・−82・) If K − is matched, then AI ” /Bl ” =A2 ” /B2
” If so, in the light ray M from the light source 105, F
When the light 11M passing through l makes an angle α with the X axis, the light 11M from the second reflecting section 102 #is reflected in a direction making an angle α with the JX axis. In this way, the position from which the light is emitted is moved by the two reflecting parts, and the light from the light source is irradiated to the outside without changing the divergence angle.

Therefore, the light distribution characteristics of the light source can be maintained.

In other words, the light ray M emitted from the light source on the focal point Fl at the angle α is reflected from the first reflection part 100 as shown in the figure.
is reflected by the reflecting surface 101 of the second reflecting section 102.
It is reflected again on the reflective surface 103 of Thereafter, the light fiM from the second reflective surface 103 is irradiated at an angle α in the same direction as the light ray M emitted from the light source 105 at the focal point F1. As a result, it is possible to change the position from which light is emitted to the outside while maintaining the light distribution characteristics of the light source without moving the light source 105. In FIG. 6, a first reflecting section 110 forming a part of a spheroid and a second reflecting section 110 forming a part of a spheroid having a long axis coincident with the long axis of the first reflecting section 110 are shown. A reflecting section 112 is arranged. Their long axes are aligned with the X axis. The first reflective surface 110 has focal points Fl, F, -, and the second reflective surface 112 has focal points P2, F2''. The first reflective section 110 and the second reflective section 112 have focal points F, - and F2 are arranged at the same position. In this case, the first reflecting section 110 has a first reflecting surface 111 on its inner surface, and the second reflecting section 112 also has a first reflecting surface 111 on its inner surface. It has a second reflective surface 113 on its inner surface.A light source 115 is placed at the focal point Fl of the first reflective section 110.In this case, similarly, the focal point F, - and the focal point F2
are matched, so it becomes +(A2・+82・)K. In this case, A, 12/B1 ” =A2 ”
/B22, then the light ray M from the light source 115 of F is
When making an angle α to the axis, the light ray M from the second reflecting surface 113
is also reflected in the direction forming the angle α. Therefore, the light emission position can be moved while maintaining the light distribution characteristics. In other words, the light ray M from the light source 115
After being reflected by the reflective surface 111 of , the focal point Fl-1F2! The light is focused. The focused light beam M passes through the second reflection section 11
The light is reflected by the second reflective surface 113 of No. 2 and condensed at a focal point F2-. The focused light 11M is irradiated in the same direction as the light ray M from Fl. In this case as well, the light emission position to the outside can be moved while maintaining the light distribution characteristics without changing the position of the light source 115.

The lighting device 1 shown in FIG. 1 is of the type shown in FIG. This lighting bag! In the construction, after the light *M emitted from the point light source 6 is reflected by the first reflective surface 2,
The focal point F of the reflecting section 4 of - and the focal point F of the second reflecting section 10
The light is focused at 2. Ray M focused at focal points Fl and F2
is reflected by the second reflecting surface 8 of the second reflecting section. The light beam M reflected by the second reflective surface 8 is condensed at the focal point F2- of the second reflective section 10 and irradiated to the outside in the same direction as the direction in which the light is emitted from the focal point F1. Therefore, light can be emitted from the second reflection section to the outside while maintaining the light distribution characteristics without changing the position of the point light source 6. FIG. 2 shows a point light source 6 at a position of Y=3 m when there is no first reflecting section 4.
Figure 3 shows the light distribution characteristics of direct light from Y=3.
The light distribution characteristics of the light from the second reflecting section 10 at the position m are shown. FIGS. 2 and 3 show 36 points around the same area with equal illuminance. As can be understood from these, light is emitted with almost no change in the light distribution characteristics. By the way, when an elongated light source is used instead of a point light source as the light source of the illumination device l, the elongated light source is the focal position Fl.
If the light beam is placed correctly at the position shown in FIG. 3, good light distribution characteristics as shown in FIG. 3 will be maintained. However, when the elongated light source moves slightly from the focal point F1 in the Smm Z-axis direction, the light distribution characteristics are not maintained and the shape becomes distorted at the position of Y=3 m, as shown in FIG. Therefore, a built-in lighting device for a camera using this elongated light source will be described next.

A second embodiment of the invention is shown in FIG. In this embodiment, an elongated light source is used as the light source. This lighting device 1 includes a first reflecting section 34 and a second reflecting section 40 each having a shape in which a part of an elliptical cylinder is cut off. The tube axis direction of the elliptical cylinder is the Z-axis direction. The first reflecting section 34 and the second reflecting section 34
Both reflecting portions 40 are formed to have a linear shape when cut along a plane parallel to the X-Z plane, and to have an elliptical shape when cut along a plane parallel to the X-Y plane. The first reflecting section 34 has a first reflecting surface 32 formed on its inner surface, and has elliptical focal points F1 and Fl-. The second reflecting section 40 has a second reflecting surface 38 formed on its inner surface, and has focal points F2 and F2-.
It has First reflective surface 34 and second reflective surface 4
0 is arranged such that the focal point F1° and the focal point F2 are aligned. The first reflecting section 34 and the second reflecting section 40 are each expressed by the following equations.

First reflective surface Therefore, each surface is: L= (A, 2+8.2)" + (A2・+82・)'/", and in this case, AI=A2, BIB2=5
2. Set AI /Bl = A2 /B2 = 1.3.

The long axes of the elliptical cross sections of the first reflecting section 34 and the second reflecting section 40 are aligned with each other. At the focal point F1 inside the first reflecting section 34, there is a light emitting tube 36, which is an elongated light source. The direction of the tube axis of the zero arc tube 36 in which the is disposed is oriented in the Z-axis direction. The light beam M emitted from this arc tube 36 is the first
The focal point F1° after being reflected by the reflecting surface 34 of the reflecting section 32
The light ray M that passes through the focal point Fl and the focal point F2 in the two axial directions connects the focal point * m 1 above the focal point F2, and is reflected by the second reflecting surface 38 of the second reflecting section 40, and then returns to the focal point F2- above. A light ray M, which connects a focal point 11 m 2 in the Z-axis direction at , and a focal line m2 connected at a focal point F2°, is irradiated to the outside in the same direction as the light ray M emitted from the arc tube 36 . FIG. 8 shows the light distribution characteristics from the second reflecting section 40 at Y=3 m.

FIG. 8 shows 36 points around the area with equal illuminance. The light distribution characteristics of direct light from the light source 36 at Y=3 m are similar to the light distribution characteristics shown in FIG. Therefore, the emission position of the light irradiated to the outside can be moved without substantially changing the light distribution characteristics from the light source 36. In addition, in FIG. 9, the arc tube 36 is placed 5 m from the focal point F1.
The light distribution characteristics of the light reflected by the second light emitting surface 38 when moved in the mZ-axis direction are shown. FIG. 9 also shows areas with equal illuminance at 36 points around the circumference. It can be seen that even if the light source is shifted from the focal point F1 in this way, by using the first and second reflecting surfaces in the shape of an elliptical cylinder, a light distribution characteristic that is almost the same as that of the light source can be obtained.

As a modification of this embodiment, circular light distribution characteristics can be obtained at a certain distance by slightly curving the first and second reflecting surfaces in the Z-axis direction.

In the first and second embodiments, the light source is placed above the focal point F1 of the first reflecting surface, but another reflecting section having a focal point aligned with the focal point F1 is used. You can also. FIG. 10 shows an embodiment in which a reflector for the light source is provided. This lighting device 1 includes a first reflecting section 52, a second reflecting section 54, and a light source reflecting section 56 having an elliptical cross section and a light source 58 therein. The first reflecting section 52 has a first reflecting surface 53 on its inner surface, and a second reflecting surface 53.
The reflecting section 54 has a second reflecting surface 55, and the light source reflecting section 56 has a reflecting section 57 on its inner surface.

The light source reflecting section 56 has focal points F3 and FB-, and a first
The second reflecting section 52 has focal points F, , F, -, and the second reflecting section 54 has focal points F2, F2-.

The long axes of the first reflecting section 52 and the second reflecting section 54 are the same, and in this case, the long axis of the light source reflecting section 56 is perpendicular to this long axis, and Part 5
2 through the focal point F1. First reflecting section 5
The long axes of the second reflecting section 2 and the second reflecting section 54 are aligned with the X axis. The focal point Fl of the first reflecting section 52 is aligned with the focal point F3 of the light source reflecting section 56, and the focal point F1 of the first reflecting section 52 is aligned with the focal point F3 of the light source reflecting section 56.
- is aligned with the focal point F2 of the second reflecting section 54. The light source 58 is arranged above the focal point F of the light source reflection section 56. In this case as well, after the light M emitted from the light source 58 is reflected by the reflection surface 57 of the light source reflection part 56,
The light is focused on the focal point F3-5F1. This focal point F3-1
The light M focused on Fl is reflected by the first reflecting surface 53 and focused on the focal points F1'' and F2.The focal point Fl-1F
The light M focused at F2 is reflected at the second reflecting surface 55, is focused at a focal point F2-, and is then irradiated to the outside. Therefore, like the other embodiments, the light emission position can be moved without changing the light distribution characteristics.

In this shape, if an attachment having a first reflecting section and a second reflecting section can be attached in front of a strobe, which is a light source built into the camera, a camera with less red-eye phenomenon can be obtained.

[Effect of the invention] Red-eye phenomenon occurs because even when using a lighting device built into a camera, it is possible to take pictures with a wider distance between the optical axis of the lighting device and the optical axis of the photographing optical system without changing the light distribution characteristics. It is possible to take good pictures without using the camera.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a lighting device according to a first embodiment of the present invention, FIG. 2 is a diagram showing light distribution characteristics of a light source of the first embodiment, and FIG. 3 is a diagram showing a lighting device according to a first embodiment. Figure 4 shows the light distribution characteristics of light from the second reflective surface in the example. Figure 4 shows the light distribution characteristics when a long and thin light source is moved 5 mm from the focal point in the Z-axis direction. 6 and 6 are diagrams for explaining the invention in detail, FIG. 7 is a perspective view showing a lighting device according to a second embodiment of the invention, and FIG. 8 is a perspective view showing a lighting device according to a second embodiment of the invention. Figure 9 is a diagram showing the light distribution characteristics of light from the second reflective surface when the elongated light source is moved 5 mm in the Z-axis direction. FIG. 10 is a plan view showing a modification of the first embodiment and the second embodiment. DESCRIPTION OF SYMBOLS 1... Illumination device, 2... 1st reflective surface, 4... 1st reflective part, 6... Point light source, 8... 2nd reflective surface,
10... Second reflecting section, 32... First reflecting surface, 3
4...i first reflecting section, 36... arc tube, 38...
2nd reflective surface, 40... 2nd reflective part, 52... 1st reflective part, 53... 1st reflective surface, 54... 2nd
55... Second reflective surface, 56... Reflective part for light source, 57... Reflective surface for light source, 58... Light source.

Claims (1)

[Scope of Claims] A light source, a first reflecting section that reflects the light from the light source in a direction away from the photographic lens, and a second reflecting section that reflects the light from the first reflecting section toward the subject. In the built-in lighting device for a camera, the cross-sectional shape of the first reflecting section and the second reflecting section cut along a plane including the optical axis of the light from the light source is approximately X^ 2/A_1^2+Y^2/B_1^2=1 (first reflecting part) (XL)^2/A_2^2+Y^2/B_2^2=1
(Second reflecting section) The second reflecting section is formed into an elliptical shape each expressed by the following formula, and the position of the light source or the position where the light from the light source is focused is at the focal position of one of the first reflecting sections. L=(A_1^2-B_1^Z ^1^/^2-
(A_2^2-B_2^2)^1^/^2 or, L=(A_1^2-B_1^2)^1^/^2+(A_
2^2-B_2^2) A built-in lighting device for a camera, characterized in that it is ^1^/^2.