JP3151252B2 - Reflection member of projection optical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflecting member of a light projecting optical system,
More specifically, the present invention relates to a reflecting member of a light projecting optical system capable of obtaining desired light distribution characteristics.

[0002]

2. Description of the Related Art As is well known, in a light projecting optical system such as a strobe used for flash photography, for example, a reflecting member for reflecting the strobe light is usually used in order to efficiently irradiate the projection light toward a subject. . A conventional example of this reflecting member will be described with reference to FIG.
1, the cross-sectional shape of the reflecting surface 11a is elliptical, and many light emitting elements 1 such as strobes are arranged near the focal position of the ellipse. The light distribution characteristic diagram simulating the light emission amount with respect to the light distribution angle in this case is as follows.
As shown in FIG.

In addition, as shown in FIG. 14, the cross-sectional shape of the reflecting surface 12a of the reflecting member 12 of the light projecting optical system is
The central portion 12a2 has an elliptical shape and a peripheral portion 1 close to the subject.
Also used are those formed linearly at 2a1 and having a light-emitting body 1 such as a strobe disposed near the focal point of the ellipse. The light distribution characteristic diagram in this case is as shown in FIGS. 15 (simulation diagram) and 16 (actually measured values), and no significant difference from that in FIG.

[0004]

However, in the light distribution characteristic diagrams shown in FIG. 13 or FIGS. 15 and 16 respectively, as is apparent from each of the figures, the range that should be flat originally has a peak. , The peripheral light intensity starts to drop from about 20 °. If an attempt is made to shoot an image with, for example, a still video camera (hereinafter, referred to as an SV camera) while irradiating with a light projecting optical system having such light distribution characteristics, the above-mentioned decrease in the amount of peripheral light becomes a particular problem.

[0005] Further, since the mounting position of the luminous body 1 with respect to the reflecting members 11 and 12 corresponds to the elliptical curved surface, the positioning of the luminous body 1 becomes difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reflecting member of a light projecting optical system which solves the above-mentioned problems, has a wide flat light distribution range, and can easily position the luminous body with respect to the reflecting member.

[0007]

In order to achieve the above object, a reflecting member of a light projecting optical system according to the present invention includes a plurality of straight lines having a continuous cross-sectional shape of a reflecting surface or a curved line having a bending point. A reflecting member of the light projecting optical system, which is configured so that the difference between the angle (X) formed by the reflecting surface side of the straight line adjacent to the straight line or the straight line connecting both ends of the curved line is constant. The end points of each of the plurality of continuous straight lines or curves are radiation extending from a point on the center line in a plane orthogonal to the center line of the light source having a cylindrical shape, and the radiation points of the radiation sequentially adjacent to each other. The angle formed is set so as to intersect with one of the plurality of radiations extending at an equal angle (Y), and the angle (Y) is defined by the reflection surface side of the straight line or a straight line connecting both ends of the curve. Twice the angle difference (X) Characterized in that it is set to be properly.

[0008]

The reflecting member of the light projecting optical system reflects, for example, light from a light emitter and distributes the light so as to be flat over a wide range.

[0009]

Embodiments of the present invention will be described below. First, prior to describing an embodiment of the present invention, its basic concept will be described.
A case where the cross-sectional shape of the reflecting surface is constituted by a plurality of continuous straight lines will be described. In this case, the difference between the angles formed by the plurality of straight lines adjacent to each other on the reflection surface side is set to be constant, and any one of the plurality of straight lines is extracted, and the luminous body is set to a point light source. The light reflection by the above-mentioned straight line when it is considered as described above will be described below with reference to FIG.

In FIG. 2, a point inclined from the straight line GF parallel to the optical axis O by an angle θ2 toward a reflecting surface whose cross section is indicated by a straight line DE is directed from the point light source A to the optical axis O at an angle θ1. When light is projected, the projected light is reflected at a point B on the straight line DE and travels in a direction extending the straight line BC. in this case,
The angle of intersection of the reflected light with the optical axis O is θ3, and the intersection is C.

If the point at which the perpendicular of the straight line DE at the point B intersects the optical axis O is H, the angle (ABH) = angle (HBC) from the reflection of light. Therefore, angle (ABD) = angle (CBE) (1). In this case, the angle (ABD) is obtained by subtracting the angle (DBG) from the angle (ABG). Since the angle (ABG) is equal to θ1 and the angle (DBG) is equal to θ2, the angle (ABD) = θ1 −θ2. ... (2) On the other hand, the angle (CBE) is obtained by adding the angle (FBE) to the angle (CBF). The angle (CBF) is equal to θ3, and the angle (FBE) is θ2, so that the angle (CBE) = θ3 + θ2 ( 3) By substituting the above equations (2) and (3) into the above equation (1), θ1−θ2 = θ3 + θ2. Therefore, the following equation (4) is obtained.

Θ3 = θ1−2θ2 (4) The above assumes a single straight line in the reflecting member composed of a plurality of straight lines having a continuous cross-sectional shape of the reflecting surface. The reflection angle θ3 indicating the light distribution range when the light is projected at the projection angle θ1 is shown as a function of the angle θ2 formed with the optical axis O of the certain straight line DE.

In this case, if the angle .theta.3 between the one straight line DE and the optical axis of the reflected light at the end D close to the photographer is a predetermined light distribution angle, the above points D are closer to the subject than the point D. Since the light distribution angle is smaller than a predetermined light distribution angle, that is, closer to the optical axis, the reflection at the end closer to the photographer will be discussed in the following description.

Now, a case where the light distribution range from the light emitter 1 is set to ± 30 ° up and down around the light projecting optical axis O as shown in FIG. 4 as a first embodiment of the present invention. Figure 1
This will be described below using Nos. 3 and 4.

In FIG. 3, the light is projected on the basis of the projection optical axis O of the luminous body 1, that is, the subject side (opening side), a = b =... F = 30 °. L1a, L1b,...
L1f. In this case, since the reflecting member of the light projecting optical system is symmetrical in the vertical direction of the light projecting optical axis O, the distribution line naturally extends downward but is not shown.

FIG. 1 shows a reflecting surface 2a according to the first embodiment in which the reflecting surface is constituted by a plurality of continuous straight lines.
L1f, L1a, L1b,..., L1f of the luminous body 1 in a case where the difference between the angles of the adjacent straight lines on the reflection surface side is set to a constant value of 15 °. is there. Since the angle difference is set to 15 °, the distribution lines are set at equal intervals over the entire circumference. However, the present embodiment is not limited to this. May be set as 11.5 °, for example.
This will be described later as a modification of the present embodiment.

First, Lf, which intersects the light projecting optical axis O at 75 ° and is in direct contact with the luminous body 1, is drawn.
The intersection with 1e is P5. Next, from this point P5, the optical axis O
Then, a straight line Le having an angle of 60 ° is drawn, and the intersection with the distribution line L1d is defined as P4. Hereinafter, similarly, straight lines Ld, Lc, L with angles of 45 °, 30 °, and 15 ° respectively with the optical axis O are formed.
b are drawn respectively, and points that intersect the distribution lines L1c, L1b, and L1a are P3, P2, and P1, respectively. Although the above description is for the upper half of the optical axis O, a plurality of continuous straight lines Lb 'to Lf' (not shown) are drawn in the same manner for the lower half, whereby the continuous straight lines Lb 'to Lf' in the reflecting member 2 of the light projecting optical system are drawn. The reflecting surface 2a composed of a plurality of straight lines is configured as shown in FIG.

The light distribution characteristics of the first embodiment thus configured will be described with reference to Table 1.

[0019]

[Table 1]

[Category 1] The projection angle θ 1 from the luminous body 1 is 0
In the projection range of ° to + 30 °, direct light is projected toward the subject.

[Category 2] Projection angle θ1 is + 30 ° to +60
The angle of reflection θ3 is θ3 = 60 ° −2 × 15 ° = 30 ° according to the above equation (4) per θ2b = 15 ° in the point P2 in FIG. It is reflected at 0-30 degrees below O.

[Category 3] Projection angle θ1 is + 60 ° to +90
Θ1 in the projection range of 90 ° is 90 °, that is, at the point P3, θ2c
Is 30 °, θ3 = 90 ° −2 × 30 ° = 30 ° from the above equation (4), and the light is reflected in the range of 0 to −30 ° as in the case of the section 2.

[Sections 4, 5, and 6] Similarly, the reflected light from each reflecting surface whose cross-sectional shape is represented by straight lines Ld, Le, and Lf, respectively, will Similarly, it is reflected in the range of 0-30 degrees.

Next, considering the projection range below the optical axis O, that is, the projection angle of 180 ° to 360 °, (a) When the projection angle θ 1 from the luminous body 1 is in the range of 330 ° to 0 °, Light is projected toward the subject.

(B) In the projection range where the projection angle θ 1 is 300 ° to 330 °, the light is reflected in the symmetrical direction with respect to the optical axis O of the section 2, that is, in the range of 0 to + 30 ° above the optical axis O.

(C) Similarly, straight lines Lc ', Ld
The reflected lights respectively reflected by ', Le' and Lf 'are projected toward a region of 0 to + 30 ° above the optical axis O.

In this case, the light distribution range projected from the light emitter 1 as direct light or reflected light to the subject is ±
Strictly speaking, the emission point varies from point A to point P1o in FIG. 4 even though it is 30 °, but since the distance between these points is considered to be negligible compared to the object distance, the first The light distribution range of the embodiment is −30 ° to +30.
°.

The following is a summary of the first embodiment. That is, when it is desired to set the light distribution range to a range from −N ° to + N °, first, the light is distributed to each N °, and then, in each distribution range, the angle θnR formed with the optical axis O is k as a positive integer. Then, by continuing a plurality of straight lines given by θnR = kN ° / 2 (5), the sectional shape of the reflecting surface of the reflecting member according to the first embodiment may be determined. . The light distribution characteristics according to the first embodiment are as shown in FIGS. 5 (simulation diagram) and 6 (actually measured values), respectively.
It can be seen that it is significantly improved as compared with 5,16.

Further, as shown in FIG. 7, the position of the luminous body 1 with respect to the reflecting member is set at a position in contact with the straight lines Lf and Lf ', so that the luminous body 1 can be accurately fixed. In the above embodiment, the light distribution range was ± 30 °, and the difference between the angles formed by the reflection surfaces of the successive straight lines was fixed at 15 °, so that the distribution could be equally performed. However, the present invention can be applied to a light distribution angle at which the distribution cannot be performed equally, and a case where the light distribution range is set to, for example, ± 23 ° is shown as a modification of the first embodiment. 2 will be described.

[0030]

[Table 2]

That is, since the distribution angle is set to 23 °, the difference between the angles of the adjacent straight lines on the reflection surface side is reduced by one.
Keep it constant at 1.5 °. Table 2 corresponds to Table 1 above.
The upper half from the optical axis O is described in the same manner as described above. In the section 11, direct light is transmitted from the upper region 0 to + 23 ° of the optical axis O.
In the sections 12 to 17, the reflected light is distributed to the areas 0 to -23 below the optical axis O. In this case, since the distribution angle is set to 23 °, which cannot be equally divided, the light distribution range is 0 ° to -19 ° in the section 18, but such a deviation is an allowable error range.

FIG. 8 is a sectional view of a reflecting surface 2Aa of a reflecting member 2A of a light projecting optical system according to a second embodiment of the present invention.
FIG. 9 is a perspective view of the second embodiment. The second embodiment is largely different from the first embodiment in that the size is reduced, and specifically, the straight lines Lb and Lb in FIGS.
Lb 'is abolished, and the straight lines Lc to Lf and the straight lines Lc' to Lf 'form the sectional shape of the reflection surface 2Aa. Accordingly, the light distribution range of the direct light is -60 ° to + 60 °, but the reflected light is the same as in the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

According to the second embodiment, as shown in FIGS. 10 and 11, the direct light irradiation range is ± 60.
°, the efficiency will slightly decrease,
In the required light distribution range ± 30 °, a sufficiently flat characteristic can be obtained and the size can be reduced.

In the above description, it has been described that the cross-sectional shape of the reflecting surface is constituted by a plurality of continuous straight lines.
As described in the basic concept of the above, when the cross-sectional shape of the reflecting surface is composed of a plurality of continuous straight lines, the angle between the optical axis of the reflected light at the end D near the photographer of one straight line DE If θ3 is a predetermined light distribution angle, even if the point D and the point E are not a straight line but a curve, the reflected light from the reflecting surface between the points D and E only needs to be within the light distribution range. Needless to say, it is not necessary to limit the cross-sectional shape to a plurality of straight lines, and it may be a plurality of continuous straight lines or curves.

Further, as the light projecting optical system, in addition to the case where a subject emits flash light during flash photography, for example, the A
Needless to say, the present invention can be applied to F (autofocus) auxiliary light and the like.

Further, even if the position where the luminous body is fixed is slightly displaced, there is no hindrance. In short, the angle formed by the adjacent straight lines or curved lines on the reflecting surface side which forms the cross section of the reflecting surface is as described in the above (5). The angle difference is set as shown in the equation, and the angle difference may be constant.

According to each of the above-described embodiments, << 1 >> the cross-sectional shape of the reflecting surface of the reflecting member of the light projecting optical system is constituted by a plurality of continuous straight lines or curved lines having bending points, thereby achieving a desired distribution. Since a flat light distribution characteristic is obtained in the light range, the peripheral light amount is likely to be a problem. For example, it is suitable as a reflecting member of a light projecting optical system for an SV camera, and is efficient.

<2> Since the cross-sectional shape of the reflecting member to which the luminous body contacts is V-shaped, accurate positioning is possible.

<3> Since the cross-sectional shape is simpler than that of a conventional ellipse or a combination of an ellipse and a straight line, mold processing is facilitated.

[0040]

As described above, according to the present invention, there is a remarkable effect that a flat light distribution range can be widened and that the positioning of the luminous body with respect to the reflection member becomes easy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a relationship between a cross-sectional shape of a reflecting surface and a distribution line in a reflecting member of a light projecting optical system according to a first embodiment of the present invention.

FIG. 2 is a view for explaining light reflection from a reflection surface indicated by a certain straight line in FIG. 1;

FIG. 3 is a view for explaining the distribution lines in FIG. 1;

FIG. 4 is a schematic view of a reflection member according to the first embodiment.

FIG. 5 is a diagram showing light distribution characteristics on rectangular coordinates in the first embodiment.

FIG. 6 is a diagram showing light distribution characteristics on polar coordinates in the first embodiment.

FIG. 7 is an enlarged view of a portion where the reflection member in FIG.

FIG. 8 is a schematic diagram showing a relationship between a cross-sectional shape of a reflecting surface and a luminous body in a reflecting member of a light projecting optical system according to a second embodiment of the present invention.

FIG. 9 is a perspective view of the second embodiment.

FIG. 10 is a diagram showing light distribution characteristics on rectangular coordinates in the second embodiment.

FIG. 11 is a diagram showing light distribution characteristics on polar coordinates in the second embodiment.

FIG. 12 is a schematic view of a reflection member of a conventional light projecting optical system.

FIG. 13 is a diagram showing light distribution characteristics in FIG. 12;

FIG. 14 is a schematic view showing another example of the reflection member of the conventional light projecting optical system.

FIG. 15 is a diagram showing light distribution characteristics on rectangular coordinates in FIG. 14;

FIG. 16 is a diagram showing light distribution characteristics on polar coordinates in FIG. 14;

[Explanation of symbols]

 2a ... Reflective surface

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03B 15/05 F21S 2/00 F21V 7/00 G02B 5/10

Claims (1)

(57) [Claims] 1. A configuration in which a cross-sectional shape of a reflecting surface includes a plurality of continuous straight lines or a curve having a bending point,
A reflecting member of a light projecting optical system which is set so that a difference between an angle (X) formed by a reflecting surface of a straight line connecting both ends of the curved line or the straight line which is sequentially adjacent is constant. Each end point of the straight line or the curved line is a ray extending from a point on the center line in a plane orthogonal to the center line of the light source having a cylindrical shape, and the angles formed by the successively adjacent rays are equiangular. The angle (Y) is set so as to intersect one of the plurality of radiations extending in (Y), and the angle (Y) is the angle (X) formed by the reflection surface side of the straight line or a straight line connecting both ends of the curve. A reflecting member of a light projecting optical system, wherein the reflecting member is set to be equal to twice the difference.