JPH01298328A - Stroboscopic device - Google Patents

Abstract

PURPOSE:To obtain excellent light condensing efficiency and light distribution characteristics from a compact device by forming a flat part which is almost vertical to the light irradiating front direction on the innermost part of a reflector and positioning a discharge tube on the flat part by allowing the tube to be brought into contact with the flat part inside or allowing it to be adjacent to the flat part. CONSTITUTION:The title device is composed of the cylinder shaped discharge tube 4, the reflector 5 which reflects the light from the discharge tube 4 in the forward direction and a condensing lens 6 provided on the front plane of the reflector 5. In this case, the discharge tube 4 is brought into contact with the inside of the reflector 5 at the innermost of the reflector, and a plane 5a which is almost vertical to the light irradiating direction is formed at the inside contacted part or the opposing part of the reflector 5. Therefore, the light generated from the part close to an object on the discharge tube 4 and proceeds to the innermost part does not have a large inclination against an optical axis after the reflection and is efficiently condensed in the vertical direction. Thus, the excellent light condensing efficiency and the light distribution characteristics are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a strobe device for a camera, and more particularly to a strobe device with improved light collection efficiency and light distribution characteristics.

(Prior Art) Conventionally, in a strobe device for a camera, as shown in FIG. It focuses the light evenly in the front.

However, in recent years, as cameras have become more compact, strobe mounts have been required to be smaller, and design requirements have also led to the use of elongated reflectors with small openings. However, in this case, the diameter of the discharge tube becomes larger than the reflector, and it becomes impossible to arrange it near the focal point as in the conventional method. In other words, when the cross-sectional shape is an ellipse, even if the discharge tube is placed at the deepest part of the reflector, the focal point of the 5-reflector will be far away from the center of the discharge tube, and will be located closer to the object than the center of the discharge tube. The part can no longer be considered near the focal point. For this reason, among the rays of light that exit from near the center of the discharge tube and head forward, most of the rays that are reflected by the reflector end up having a large angle to the optical axis after one reflection, and end up heading out of the field of view. . The closer the light emitting position is from the tube center to the object side, the larger this angle becomes.

For this reason, a condensing lens 3 placed in front of the reflector l as shown in Fig. 7 has been used in the past, but even this does not improve the light distribution characteristics much, as shown in Fig. 1. In this case, the light rays exiting from the part of the discharge tube 2 near the object and heading in the same direction have a large angle with the optical axis after being reflected twice, and are directed outside the angle of view. 3, it is conversely diverged and further radiated out of the field of view.

Figure 8 shows the combination of a conventional elliptical reflector and lens (
As mentioned above, since the light ray has a large angle with respect to the optical axis, a second peak is formed outside the angle of view, resulting in poor light collection efficiency.

As described above, in a small strobe device, the conventional umbrella shape having an elliptical cross section is inefficient and requires special consideration.

(Objects and Structure of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to provide a strobe device that is compact and has excellent light collection efficiency and light distribution characteristics. In order to achieve such an object, in the present invention, a part of the discharge tube is inscribed or opposed to the inner part of the reflector, and a surface substantially perpendicular to the light irradiation direction is formed in the inner part or the opposing part of one reflector. It was configured to do so.

(Embodiment) Fig. 1 is a cross-sectional view of an embodiment of a strobe device according to the present invention, where 4 is a cylindrical discharge tube with a radius of a and a length of about 20 mm, and 5 is a light emitted from the discharge tube 4. A reflector 6 is a condenser lens provided on the front surface of the reflector 5 to reflect the light forward.

Now, if we take the XY coordinate axes as shown in FIG. 1 and express the cross-sectional shape of the reflector 5 using these xY coordinates, the maximum value IX1 in the vertical direction of the reflector 5 will be obtained. ．． ．． is 1.5a<lX1. ,,
<3a...(1) Maximum value in the depth direction IY1. ．． ．． is 1.51 xllllllml < Y malI <
31 xl−w”” (2). In addition, a discharge tube 4 is inscribed in the inner part of the reflective umbrella 5.
When the cross-sectional shape of is expressed as the function @Y=F (X) and the differential coefficient of -E-(7) is expressed as F' (X), 1F'(±a/2)I<0.3a= (3) F (X) is determined so that That is, the reflective umbrella 5
A surface 5a substantially perpendicular to the light irradiation direction (Y-axis direction) is formed in a portion where -a/2 < x < a/2.

Equations (1) and (2) limit the size of the strobe device. Among them, equation (1) relates to the opening direction of the reflector 5, and when the upper limit is exceeded, the compactness is lost, and when the lower limit is exceeded and the size becomes smaller, the light collecting function is significantly deteriorated. Similarly, equation (2) relates to the depth of the reflector 5, and the upper and lower limits are determined in consideration of compactness and light gathering function, respectively.

Equation (3) relates to the inclination of the surface 5a of the reflector 5, and by making it almost perpendicular to the light irradiation direction (Y-axis direction) than the conventional elliptical shape, the object of the discharge tube 4 can be Even when the light is emitted from the closer part and goes towards the inner part, the light does not have a large inclination angle with respect to the optical axis after one reflection, making it possible to effectively collect the light in the right angle direction.

In this example, the radius of the discharge tube is a = 1.5 [mml, 1XL
a*= 2 a = 3 [mal, y
saw = 2 1X1. ,,=6[mml
It is set to . In addition, the cross-sectional shape of the reflective umbrella 5 is expressed as follows, where 1F'(±a/2)140.150<0.3a, and the first surface 5a is approximately perpendicular to the light irradiation direction (Y-axis direction). There is.

With conventional elliptical reflectors, among the rays of light that are emitted from the part of the discharge tube near the subject and head toward the rear, only those that travel in the direction of the angle of view after one reflection are reflected in a very narrow range near the apex of the reflector. However, in this embodiment, the reflected light beam can be directed in the direction perpendicular to the image over a fairly wide area around the apex. As a result, as shown in FIG. 2, the light distribution characteristic has become appropriate, with the peak in the first periphery disappearing.

FIG. 3 shows another embodiment of the strobe device according to the present invention, and this embodiment also has a discharge tube 4 similar to the first embodiment.
radius a=1.5 [am], lXl5ax"2a=3
[am] , Y, , =21Xl, am=6[, +
m], and the cross-sectional shape of the reflector 5 is expressed as 1F'(±a/2)l"; 0.016. In this embodiment, compared to the first embodiment, the surface 5a is further widened. Therefore, when using the same condensing lens as in the first embodiment, the light distribution diagram shows that the light is more concentrated in the center as shown in Fig. 4, and the angle of view is slightly reduced. This makes it suitable for small cameras.

Isn't the condensing lens 6 an essential component of the present invention? If the condensing lens 6 is placed in front of the reflective umbrella 5 as in the embodiment, the light condensing efficiency and light distribution characteristics can be further improved. . The refractive surface of this condensing lens may be a single curved surface or a Fresnel surface. When using a Fresnel surface, if a ring-shaped one is used, the refraction effect in the short side direction becomes smaller when a long and slender reflector is used as in the example, so the refraction effect is reduced on the inside and outside of the lens. It is preferable to arrange the refractive powers so that the directions are perpendicular to each other.

In the above embodiment, the outer surface of the condenser lens 6 has a refractive power in the short side direction (X-axis direction), but the inner surface of the condenser lens has a straight Fresnel having a refractive effect in the long side direction. It can also be used as a mask. A sectional view in the long side direction at this time is shown in FIG. In the figure, 7 is a condensing lens whose inner surface 7a is a linear Fresnel, 4 is a discharge tube, and 5 is a reflective umbrella.

Further, in the above embodiment, the discharge tube 4 and the surface 5a are in contact with each other, but the discharge tube 4 may be placed a little apart from the surface 5a.

(Effects of the Invention) As explained above, according to the present invention, a part of the discharge tube is inscribed or opposed to the inner part of one reflective umbrella, and the inscribed part or the opposite part of one reflective umbrella is approximately parallel to the light irradiation direction. Since it is configured to form a right-angled surface, it is possible to provide a compact strobe device with excellent light collection efficiency and light distribution characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of a strobe device according to the present invention, FIG. 2 is a light distribution characteristic diagram of the device of FIG. 1, FIGS. 3 to 5 are diagrams showing other embodiments, and FIG. 7 and 7 are schematic diagrams showing a conventional strobe device, and FIG. 8 is a light distribution characteristic diagram of the device shown in FIG. 7. 1.5...Reflector, 2,4...Discharge tube, 3,6゜7
···Condenser lens

Claims (1)

[Claims] In a strobe device that has a cylindrical discharge tube and a reflective umbrella that surrounds the discharge tube with an opening left behind, and that irradiates light from the discharge tube through the opening, the light irradiation front direction is set at the deepest part of the reflective umbrella. What is claimed is: 1. A strobe device characterized in that a flat surface is formed substantially perpendicular to the flat surface, and a discharge tube is disposed inscribed in or adjacent to the flat surface.