JP2001337372A - Strobe light emitting part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strobe light emitting part capable of reducing an irregular flux distribution of strobe light with a a simple constitution. SOLUTION: Plural cylindrical lens surfaces in concave shape 16 extended like belts are arranged in parallel and formed on a protector 15. The curvature of the lens surface 16 is continuously changed in its length direction so that the top position 16a of the concave surface may draw a sine waveform on a plane including an optical axis and parallel with a discharge tube. Light transmitted through the lens surface 16 is diverged in the width direction and the length direction of the lens surface 16, and condensed light quantity on a specified spot gets small. A formed bright part or dark part becomes a spot state, and the irregular flux distribution gets inconspicuous. Then, post- processing need not be performed when the protector 15 is produced, and the production cost thereof does not rise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic flash unit having a protector.

[0002]

2. Description of the Related Art Strobe devices incorporated in cameras are:
It is composed of a strobe substrate on which a strobe circuit for controlling charging and discharging is formed, and a strobe light emitting section for emitting strobe light. The flash unit is basically
A rod-shaped discharge tube that emits light when a trigger signal is received,
It is composed of three parts: a reflector that reflects the light emitted from the discharge tube forward, and a protector that diverges the light emitted forward toward the subject.
In such a strobe light emitting portion, since light distribution unevenness easily occurs due to a molding error of the reflector and a positional deviation between the discharge tube and the reflector, the strobe light is diverged.
Light distribution unevenness is reduced.

[0003] The protector is provided so as to cover the front side of the reflector, and is made of a resin or a glass material having optical transparency. As shown in FIG. 8, the protector 5 includes
A plurality of concave cylindrical lens surfaces 6 extending in a predetermined direction are formed in parallel on an inner surface 5a on which light emitted from the discharge tube is incident. Generally, the cylindrical lens surface 6 is formed long in a direction parallel to the rod-shaped discharge tube. As shown in FIG. 9, each cylindrical lens surface 6
Are formed in the same surface shape with a curvature radius r and a width w.

[0004]

As described above, the use of the protector alleviates the uneven light distribution caused by the positional shift between the discharge tube and the reflector. However, a protector having a cylindrical lens surface is required to maintain a high degree of positional accuracy with respect to a discharge tube and a reflector, and if not arranged at an appropriate position, conversely condenses transmitted light. Since the cylindrical lens surface strongly diverges light in the width direction, the protector 5 provided with the long cylindrical lens surfaces 6 arranged in parallel with each other, as shown in the light distribution diagram of FIG. Band-like bright portions 7 and dark portions 8 extending in parallel directions are likely to occur.

Therefore, a light diffusing substance is added to the surface of the protector formed on the flat surface, or the surface of the protector is subjected to embossing to prevent the light from condensing and to uniformly irradiate the strobe light. However, in these methods, the amount of divergence of light becomes too large, so that not only the amount of strobe light projected into the photographing range decreases, but also the number of manufacturing steps of the protector increases, leading to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a strobe light emitting section which can reduce the uneven light distribution of strobe light with a simple configuration.

[0007]

In order to achieve the above object, the present invention provides a strobe light-emitting section, comprising a concave surface extending parallel to a discharge tube on a surface of a protector on which light emitted forward is incident. A plurality of cylindrical lens surfaces are formed in parallel, and the curvature of each cylindrical lens surface is changed depending on the position in the longitudinal direction of the cylindrical lens surface.

Further, the strobe light emitting section according to the second aspect of the present invention includes an optical axis of the cylindrical lens surface, and on the plane parallel to the discharge tube, the apex position of the concave surface draws a sinusoidal waveform. The curvature is changed continuously along the length direction of the lens surface.

Further, in the strobe light emitting portion according to the third aspect, the cylindrical lens surface is constituted by arranging a plurality of concave basic cylindrical lens surfaces having a constant curvature in the longitudinal direction, and adjacent basic cylindrical lens surfaces. So that the vertex position of each concave surface is stepped,
It is formed by shifting the position in the width direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a strobe light emitting section 10 has a rod-shaped discharge tube 11 which emits light upon receiving a trigger signal, and directs light projected from the discharge tube 11 forward. And a protector 15 for diverging light emitted forward toward the object side
It is composed of The protector 15 is made of a resin or glass molded product having optical transparency, and is arranged so as to cover the open front surface of the reflector 12. The protector 15 not only controls the optical path of the strobe light, but also prevents foreign substances such as dust from entering the inside of the strobe light emitting unit 10 and makes the inside of the strobe light emitting unit 10 difficult to see to enhance the design. Have.

As shown in FIG. 2, the protector 15 includes
Inner surface 15a on which light emitted from discharge tube 11 is incident
Further, a plurality of cylindrical lens surfaces 16 extending in a belt shape are formed in parallel. As shown in FIG. 3 in a partially enlarged manner, each cylindrical lens surface 16 is formed in a concave shape, and the curvature of the concave surface differs depending on the position in the length direction of the cylindrical lens surface 16.

FIG. 4 is a cross-sectional view of a main part of the protector 15, which is a cross-sectional view including a plane parallel to the discharge tube 11 and including the optical axis of the cylindrical lens surface 16. As shown in the figure, the cylindrical lens surface 16 is located at the vertex position 1 of the concave surface.
The curvature continuously changes along the length direction of the cylindrical lens surface 16 so that 6a (see FIG. 3) draws a sine waveform.

By changing the curvature of the cylindrical lens surface 16 in accordance with the position in the length direction, light transmitted through the cylindrical lens surface 16 is diffused not only in the width direction of the lens surface 16 but also in the length direction. Become like Thereby, the strobe light emitting unit using the protector 15
Compared to the case where the conventional protector 5 in which the curvature of the lens surface is constant is used, the amount of light condensed on a specific portion is reduced, and the brightness difference within the photographing range is reduced. Further, on a plane including the optical axis of the cylindrical lens surface 16 and parallel to the discharge tube 11, the curvature of the lens surface 16 is continuously changed along the length direction such that the apex position 16a of the concave surface draws a sine waveform. By changing the distribution, as shown in the light distribution diagram of FIG. 5, the protector 15 has a bright portion 17 and a dark portion 18 caused by uneven light distribution, and has a spot-like shape. 5, light distribution unevenness is less noticeable.

Further, since the protector 15 merely devises the lens surface shape of the cylindrical lens surface formed on its surface, it is not necessary to perform post-processing on the protector 15 and the manufacturing cost does not increase.

FIG. 6 shows another configuration example of a protector embodying the present invention. The protector 20 has a surface 20a on which light emitted from a discharge tube (not shown) is incident.
, A plurality of concave cylindrical lens surfaces 21 are formed. Each cylindrical lens surface 21 is formed by forming a plurality of concave basic cylindrical lens surfaces 22 having a constant curvature in the longitudinal direction, as indicated by hatching in the figure. The basic cylindrical lens surfaces 22 arranged in the length direction have the apex positions 22a of the respective concave surfaces (FIG. 7).
(See FIG. 2) is shifted in the width direction so as to be stepped with respect to the adjacent basic cylindrical lens surface 22.

In the protector 20, the conventional protector 5
Similarly, the light transmitted through each basic cylindrical lens surface 22 is strongly diverged in the width direction of the lens surface 22.
Due to uneven light distribution, a strip-shaped bright portion or dark portion extending in a direction parallel to the lens surface 22 is generated. However, since the length of each basic cylindrical lens surface 22 is short, the positions are shifted in the width direction so that the center positions 22a of the adjacent lens surfaces 22 do not line up in the length direction. In the case where the protector 20 is not arranged at an appropriate position and light distribution unevenness occurs, a strip-shaped bright portion or dark portion is generated stepwise. Therefore, light distribution unevenness is less noticeable than a conventional protector in which a long band-shaped bright portion or dark portion occurs.

[0017]

As described above, according to the strobe light emitting portion of the present invention, the concave cylindrical lens surface extending parallel to the discharge tube is provided on the surface of the protector where the light emitted forward is incident. Are formed in parallel with each other, and the curvature of each cylindrical lens surface is changed depending on its position in the length direction, so that light transmitted through the cylindrical lens surface is diverged not only in the width direction but also in the length direction. Become like As a result, compared to the case of using a conventional protector having a constant curvature of the lens surface, the stroboscopic light emitting portion using this protector has a smaller amount of light condensed to a certain location, and the The brightness difference becomes smaller.

Further, the curvature of the cylindrical lens surface is
Containing the optical axis, the vertex position of the concave surface on a plane parallel to the discharge tube draws a sinusoidal waveform, and is continuously changed along the length direction of the lens surface, so that a bright portion caused by uneven light distribution and The dark part becomes spot-like, and the occurrence of light distribution unevenness becomes inconspicuous.

Further, the cylindrical lens surface is constituted by arranging a plurality of concave basic cylindrical lens surfaces having a constant curvature in the longitudinal direction, and the adjacent basic cylindrical lens surfaces are arranged such that the apex position of each concave surface is stepped. By shifting the position in the width direction as described above, a bright portion or a dark portion caused by uneven light distribution becomes a strip shape. Therefore, as compared with a conventional protector in which a long band-shaped bright portion or dark portion occurs, the occurrence of uneven light distribution is less noticeable.

Further, since the strobe light emitting portion of the present invention merely devises the lens surface shape of the cylindrical lens surface formed on the protector, it is not necessary to perform post-processing on the molded protector, thereby increasing the manufacturing cost. There is no.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a strobe light emitting unit.

FIG. 2 is a schematic diagram showing a configuration of a protector embodying the present invention.

FIG. 3 is an enlarged view of a main part of the protector of FIG. 2;

FIG. 4 is a sectional view of a main part showing a surface shape of a cylindrical lens surface of FIG. 3;

FIG. 5 is a light distribution diagram by the protector of FIG. 2;

FIG. 6 is a schematic diagram showing another configuration example of a protector embodying the present invention.

FIG. 7 is an enlarged view of a main part of the protector of FIG. 6;

FIG. 8 is a schematic diagram showing a configuration of a conventional protector.

9 is a cross-sectional view of a principal part showing a surface shape of a cylindrical lens surface of FIG. 8;

FIG. 10 is a light distribution diagram by the protector of FIG.

[Explanation of symbols]

 5, 15, 20 Protector 6, 16, 21 Cylindrical lens surface 16a, 21a Apex position 7, 17 Light portion 8, 18 Dark portion 10 Strobe light emitting portion 11 Discharge tube 12 Reflector 22 Basic cylindrical lens surface

Claims (3)

[Claims] 1. A rod-shaped discharge tube that emits light in response to a trigger signal, a reflector that reflects light projected from the discharge tube toward the front, and diverges and transmits light emitted toward the front. In the stroboscopic light emitting portion comprising a protector, the protector is formed with a plurality of concave cylindrical lens surfaces extending in parallel with the discharge tube on a surface on which the light emitted forward is incident. And
A stroboscopic light emitting section characterized in that each cylindrical lens surface has a different curvature depending on its position in the length direction. 2. The cylindrical lens surface has a curvature that is continuous along a length direction of the lens surface on a plane parallel to the discharge tube including an optical axis such that a vertex position of the concave surface has a sinusoidal waveform. 2. The strobe light emitting section according to claim 1, wherein: 3. The cylindrical lens surface is configured by arranging a plurality of concave basic cylindrical lens surfaces having a constant curvature in the longitudinal direction, and the adjacent basic cylindrical lens surfaces have stepped vertices at respective concave surfaces. The strobe light emitting section according to claim 1, wherein the strobe light emitting section is formed so as to be shifted in a width direction.