JP2000267157A - Stroboscopic device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stroboscopic device for a camera capable of simplifying the design of a strobe light emitting part fit to a strobe light emitting tube, improving light condensing efficiency and obtaining light distribution and exposure near to a design value. SOLUTION: A periphery reflection part 34 is made a U-shaped curved reflection surface 34a so that both ends may be opposed from an up-and-down direction, and formed at a linearly symmetric position with a horizontal line passing the center (hereinafter referred to merely as a center) 30a of the strobe light emitting tube as a reference line S1. Assuming that inside diameter tangents from a reflector end point 38 being a joint with a protector 32 covering over the front surface of a reflector 31 to the strobe light emitting tube 30 are S4 and S5, and angles formed by S4 and S5 to the reference line S1 are θ3 and θ4 (θ3>θ4), the reflector end point 38 is positioned so that a difference between θ3 and θ1 may be within the range <=6.2 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash device for a camera.

[0002]

2. Description of the Related Art A lens-equipped film unit, which is a kind of a simple camera, in which an unexposed photographic film is previously loaded in a unit body having a built-in simple photographing mechanism, is manufactured and sold by the present applicant. There are various types of film units with a lens, and some have a built-in strobe device so that they can be used for indoor or nighttime shooting.

A strobe device built in such a film unit with a lens, a compact camera, etc.
It has a simplified structure for inexpensive manufacturing,
In many cases, a strobe light emitting unit, electric components forming a strobe circuit, and the like are mounted on a printed circuit board to form a unit.

The strobe light emitting section includes a strobe light emitting tube into which gas is injected, a reflector for reflecting the light of the strobe light emitting tube forward, a reflector case for housing and holding these, and a front surface of the reflector case. And a transparent protector to be attached. The strobe light tube emits light when the electric charge charged in the main capacitor is discharged inside.

[0005] The reflector is formed by bending an aluminum plate, and has an arc-shaped receiving surface for receiving a flash tube. A trigger terminal is arranged in the reflector case, and the trigger terminal is in contact with the outer surface of the reflector. When the shutter is pressed during shooting, when a trigger voltage generated by the trigger transformer is applied to both poles of the arc tube and the trigger terminal in synchronization with the shutter release operation,
The gas in the strobe light tube is ionized, the electric energy is changed to the energy of light, and discharge is performed momentarily between the two poles, and a strong flash (strobe light) is emitted.

Light-collecting efficiency (light reaching into the image plane / total light from strobe light-emitting tube) is a performance of the strobe device.
In order to improve the light collection efficiency, various strobe devices have been proposed by the present applicant. For example,
On the cross section perpendicular to the axial direction of the stroboscopic arc tube, the reflector is formed as a curved reflection surface having an elliptical arc shape, or a curved anti-slope surface is formed by a function curve such as a hyperbola. Furthermore, it is possible to increase the light-collecting efficiency by giving a lens effect to a transparent protector that covers the front surface of the reflector.

[0007]

The cross-sectional shape perpendicular to the axial direction of the stroboscopic arc tube is a hollow circle. Conventionally, however, the stroboscopic light source is regarded as a point light source at the center of the stroboscopic arc tube on the cross section. Reflectors, protectors and the like have been designed to improve light efficiency. Therefore, the light distribution and exposure coefficient predicted at the time of design may differ from the light distribution and exposure coefficient obtained in an actual product, and there has been a problem of variation in light collection efficiency.

The present invention has been made to solve the above problems, and simplifies the design of a strobe light emitting portion suitable for a strobe light emitting tube, improves light collection efficiency, and obtains light distribution and exposure close to the design values. It is an object of the present invention to provide a strobe device.

[0009]

In order to achieve the above object, according to the present invention, a cylindrical strobe light emitting tube and a U-shaped curved reflecting surface are formed so that both ends thereof are opposed to each other from above and below, In a camera strobe device having a reflector that reflects strobe light emitted from the strobe light tube toward a subject, and a protector that covers a front surface of the reflector, the strobe light device has a cross section perpendicular to a major axis direction of the strobe light tube. The angle between a reference line passing through the center of the strobe light emitting tube and a line connecting the center of the strobe light emitting tube and the end point of the reflector on the protector side is in a range of 40.7 degrees or more and 44.5 degrees or less. At the same time, when the distance from the center of the strobe arc tube to the reflector end point is L, the distance from the reflector end point to the inner diameter of the strobe arc tube extends. That the tangent is obtained by the following angle 39 / L between the line connecting the reflector end points of the center and the protector side of the flash light emitting tube (degrees).

The difference between the reference line, the tangent angle of the curved reflecting surface at the end point of the reflector, and the angle of view of the camera is substantially parallel within ± 5 degrees.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a lens-equipped film unit, which is a simple camera, incorporating a strobe device of the present invention. The lens-fitted film unit includes a front cover 2 and a rear cover 3 forming a front surface and a rear surface, and a main body base 4, an exposure unit 5, and a strobe device 6 covered by these covers. A film roll chamber 8 and a cartridge chamber 9 are formed in the main body base 4, and a film roll 10 and a cartridge 11 are loaded into each of them at the time of manufacture. A film winding knob 12 is mounted above the cartridge chamber 9, and a winding shaft projecting from the lower end thereof is engaged with a spool shaft of the cartridge 11.

The exposure unit 5 is formed as a unit by mounting various mechanisms necessary for photographing, such as a photographing lens 13, a shutter mechanism including shutter blades, a film winding mechanism, a counter mechanism, and a finder optical system, on a base member 12. .

The strobe device 6 is based on a printed circuit board 15 in which a strobe circuit is incorporated, and has a strobe light emitting section 16 including a strobe light emitting tube, a main condenser 17,
A battery 20 is held in addition to circuit components such as a neon tube 18 and a synchro switch 19. When the charging button 24 of the front cover 2 is pressed, the contact piece 21 comes into contact with a predetermined contact to start charging the main capacitor 17. When the charging is performed to a specified level, the neon tube 18 for displaying the completion of charging is turned on. Light.

Then, when the shutter release is performed after confirming that the neon tube 18 is turned on, a current flows through the trigger coil and the voltage is raised to a voltage of several thousands to several tens of thousands volts. Is turned on, and strobe light is emitted from the strobe light emitting section 16 toward the subject.

The front cover 2 has a shutter button 22, a finder objective window 23, and a charge button 24, and also has openings 13a and 16a for exposing the photographing lens 13 and the strobe light emitting section 16. . The front cover 2 is mounted on the front side of the main body base 4 to which the exposure unit 5 and the strobe device 6 are mounted so as to cover them.

A finder eyepiece window 25 is formed on the rear cover 3 at a position facing the finder objective window 23 so that a finder image can be observed through a finder optical system lens mounted on the exposure unit 5. An opening 26 is formed near the finder eyepiece window 25 so that the lighting of the neon tube 18 can be confirmed through the opening 26.

FIG. 2 is an exploded perspective view of a strobe light emitting section 16 which is a part of the strobe device 6. Strobe light emitting unit 1
Reference numeral 6 denotes a strobe light emitting tube 30, a reflector 31, a protector 32, and a reflector case 33. The stroboscopic light emitting tube 30 is a hollow cylindrical discharge tube into which gas is injected. When a charged high-voltage current from the main capacitor 17 is applied to both electrodes of the discharge tube and a trigger terminal, the gas is ionized, and electricity is discharged. The energy is converted into light energy, discharge is performed momentarily between the two poles, and emits a strong flash (hereinafter, referred to as strobe light).

The reflector 31 is formed by press-molding a single thin aluminum plate, and is arranged so as to cover the periphery of the inserted strobe light emitting tube 30, and a peripheral reflecting portion for reflecting the strobe light to the front. 34 and the strobe light emitting tube 30
And a side reflector 35 for reflecting strobe light to the front surface. Further, the reflector 31 is incorporated into the front surface of the reflector case 33, and the openings 3 formed on both side surfaces of the reflector 31 are formed.
A strobe light emitting tube is inserted into 1a and 31b to hold the strobe light emitting tube.

The protector 32 is made of a transparent plastic, and has a strobe light emitting tube 30 and a reflector 31.
Is protected from the front side, and the strobe light is uniformly dispersed. The protector 32 is provided with an engagement plate 32 a protruding therefrom, and is engaged with an engagement claw 33 c formed on an upper surface of the reflector case 33.

The reflector case 33 integrally holds the strobe light emitting tube 30, the reflector 31, and the protector 32 as the strobe light emitting portion 16, and has an engaging claw 33c which engages with an engaging plate 32a of the protector 32 on its upper surface. It is formed. The strobe light emitting section 16 configured as described above
Is assembled on the printed circuit board 15 and constitutes a part of a flash device.

FIG. 3 schematically shows a cross section perpendicular to the long axis direction of the strobe light emitting tube in the strobe light emitting portion and the effective irradiation area EA of the strobe light forming the photographing range.
The peripheral reflecting portion 34 has a U-shaped curved reflecting surface 34a such that both ends thereof are opposed from each other in the vertical direction, and a horizontal line passing through the center (hereinafter simply referred to as the center) 30a of the strobe light emitting tube is defined as a reference line S1. It is formed at a symmetric position.

The effective irradiation area EA is a photographing range of the camera. The shooting range is the shooting lens and aperture,
And a range determined by the screen size of the photo film, and refers to a rectangular range where a subject is exposed on the photo film.
Then, at the time of flash photography, it is necessary that the quantity of flash light capable of sufficiently exposing reaches the end of this photography range, and is referred to as an effective irradiation area for the flash device.

In this cross section, the protector 32 covers the peripheral reflector 34 and the front surface of the reflector 31 from the center 30a.
The line connecting the reflector end point 38, which is the seam with
Assuming that the angle formed by S2 with respect to the reference line S1 is θ1, θ1 is set in a range of 40.7 ° to 44.5 °. And the effective irradiation area E from the center 30a
A line connecting the effective irradiation end 39 of A to S3 is referred to as a reference line S
Assuming that the angle formed by S3 with respect to 1 is θ2, the aforementioned θ1
(40.7 ° to 44.5 °) is 2 to 2.5 compared to θ2.
The position of the reflector end point 38 is determined so that the angle is within the double range.

From the reflector end point 38 to the strobe light emitting tube 3
Assuming that the inner diameter tangents to 0 are S4 and S5, and the length from the center 30a on the S2 line to the reflector end point 38 is LS (mm), the angle between each of the S2 and the inner diameter tangents S4 and S5. θ6 is set to 39 / LS (degrees) or less (see FIG. 4).

The inner diameter tangent S
4 and S5 are defined as θ3 and θ4 (θ3> θ
As 4), the position of the reflector end point 38 is determined so that the difference between θ3 and θ1 is within a range of 6.2 degrees or less.

Further, the tangent of the curved reflecting surface 34a at the reflector end point 38 is S6, and the tangent to the reference line S1 is S6.
6, the inclination of the curved reflecting surface 34a of the reflector 31 is determined so that the difference between θ1 and θ5 is substantially parallel within ± 5 degrees.

Next, the operation of the present embodiment will be described. As shown in FIGS. 4 and 5, at the time of flash shooting, flash light is emitted forward from the flash light emitting tube 30 in synchronization with the shutter release. A part of this strobe light directly irradiates the effective irradiation area EA, and the other part goes to the peripheral reflection part 34 and the side reflection part 35 of the reflector 31 and irradiates the effective irradiation area as reflected light.

The optical path L of the strobe light directly irradiated from the center 30a to the effective irradiation end 39 of the effective irradiation area EA, and is reflected from the center 30a on the curved reflecting surface 34a of the reflector end point 38 before being irradiated onto the effective irradiation area EA. The reflector end point 38 passes through the optical path L1 of the strobe light and on the inner diameter tangent S4.
The effective irradiation area EA after being reflected by the curved reflection surface 34a
Let L2 be the optical path of the strobe light irradiated to the effective illumination area EA after passing through the inner diameter tangent S5 and reflected by the curved reflecting surface 34a of the reflector end point 38.

L1 irradiates substantially the center L1 'of the effective irradiation area EA. In addition, since the angle difference between L2 and L3 with respect to L1 is 6.2 degrees or less, the light is radiated almost parallel to L1 to the same position L2 ′ and L3 ′ as the center L1 ′ of the effective irradiation area EA. . As described above, even when the strobe light source is an actual distributed light source, the light distribution is not dispersed, and light rays can be efficiently collected.

[0030]

FIG. 6 shows the result of actually measuring the relationship between the light-collecting efficiency and the distance "L" from the center of the flash tube to the end point of the reflector. The light-collecting efficiency is a numerical value that represents, as a percentage, how much of the strobe light reaches a subject to be actually photographed when the total amount of strobe light emitted from the strobe light emitting tube is 100.

The light-collecting efficiency varies slightly depending on the focal length of the lens and the film size.
It is around 0%. If the light collection efficiency is lower than this, the loss becomes too large, which is not preferable. In the present invention,
The angle between the tangent line extending from the reflector end point to the inner diameter of the strobe light emitting tube and the line connecting the center of the strobe light emitting tube and the reflector end point is set to “39 / L (degree)”. This is because if the size is increased, the light collection efficiency is sharply reduced.

If the angle is made extremely smaller than the above expression, a stroboscopic luminous tube having a very small aperture must be used, and there is a concern that the amount of emitted light may be insufficient, and the cost of parts may increase. Occurs. Considering these, by setting the angle to "39 / L (degree)", it is possible to design an optimal reflector.

As shown in FIGS. 3 and 4, the reflector 31
The intersection of the reference line S1 with the line connecting both the upper and lower end points is denoted by P, and when designing a reflector having a length LP of 6.5 mm between the point P and the center 30a of the strobe light emitting tube 30, the reference line S1 The angle made by S2 with respect to θ1 is 44.5 which is the maximum.
, The length LS from the center 30a to the reflector end point 38 is about 9.13 mm. And this length LS
The angle θ6 formed between S2 and the inner tangents S4 and S5 is calculated to be about 4.28 °. In the case of a 6.5 mm LP reflector, the angle θ6 should be set to about 4.28 ° or less. .

When the inner diameter of the strobe light emitting tube 30 is determined from the angle θ6 between S2 and the inner diameter tangent lines S4 and S5, the inner diameter needs to be 1.36 mm or less. When the thickness is set to 0.4 mm, the outer diameter of the flash tube 30 becomes 2.16 mm. This indicates that the strobe light emitting tube 30 should have an outer diameter of 2.16 mm or less.

Further, when the focal length of the camera equipped with the strobe device is 32 mm and the width of the photographic film is 24 mm (12 mm on one side), the angle of view is tan ^-1 (12/32) = 20.6 °. And
Tangent line S at reflector end point 38 with respect to reference line S1
The inclination of the curved reflecting surface 34a of the reflector 31 is determined so that the angle between 6 and θ5 is substantially parallel to θ1 within ± 5 degrees.

The reflector 3 created on the basis of these
1 indicates that the reflection efficiency is good, and the result of the predicted value at the time of design and the result of the actual measurement value of the actual product are almost equal.

In the above embodiment, the reflector 31 is formed by press-molding an aluminum plate. However, the metal plate used is not limited to the aluminum plate, but may be made of a material having conductivity and high reflectance. If so, another metal plate may be used. Instead of press-molding a metal plate, a reflector may be formed of a synthetic resin molded product, and a metal film may be deposited on the reflection surface of the reflector.

Further, in the above-described embodiment, an example of a film unit with a lens has been described as a camera on which the strobe device of the present invention is mounted, but it is needless to say that the present invention can be applied to other general cameras in the same manner. is there.

[0039]

As described above, according to the present invention,
A cylindrical strobe light emitting tube, and a reflector having a U-shaped curved reflecting surface formed so that both ends thereof face each other from above and below, and reflecting the strobe light emitted from the strobe light emitting tube toward a subject, A strobe device for a camera having a protector for covering a front surface of the reflector, a reference line passing through the center of the strobe arc tube in a cross section perpendicular to a long axis direction of the strobe arc tube; When the angle between the line connecting the reflector end point on the protector side is in the range of 40.7 degrees or more and 44.5 degrees or less, and the distance from the center of the strobe light emitting tube to the reflector end point is L A tangent line extending from the end point of the reflector to the inner diameter of the strobe light emitting tube, and a reflector at the center of the strobe light emitting tube and at the protector side. The angle between the line connecting the point 3
9 / L (degrees) or less, the light distribution prediction at the time of designing the strobe device is accurately reflected, the design of the strobe light emitting portion suitable for the strobe light tube is simplified, the light collection efficiency is improved, and the design value is improved. It is possible to provide a strobe device for a camera which can obtain a light distribution and an exposure close to the above.

Further, an angle between the reference line and a line extending from the center of the strobe light emitting tube toward the end of the photographing range of the camera, an angle between the reference line and a tangent of the curved reflecting surface at an end point of the reflector. Is substantially parallel within ± 5 degrees, it is possible to minimize the useless strobe light that goes out of the shooting range, and it is possible to efficiently illuminate the subject.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a film unit with a lens loaded with a strobe device of the present invention.

FIG. 2 is an exploded perspective view of a strobe light emitting unit.

FIG. 3 is a schematic sectional view of a strobe light emitting unit.

FIG. 4 is an explanatory diagram of an irradiation area of strobe light.

FIG. 5 is an explanatory diagram of an irradiation area of strobe light.

FIG. 6 is a graph showing the relationship between the light collection efficiency and the distance from the center of the strobe light emitting tube to the end point of the reflector.

[Explanation of symbols]

 Reference Signs List 30 Strobe arc tube 30a Strobe arc tube center 31 Reflector 32 Protector 38 Reflector end point 39 Effective irradiation end

Claims (2)

[Claims] 1. A strobe light tube having a cylindrical shape and a U-shaped curved reflecting surface formed so that both ends thereof are opposed to each other from above and below, and strobe light emitted from the strobe light tube is directed toward a subject. In a camera strobe device having a reflecting reflector and a protector covering a front surface of the reflector, in a cross section perpendicular to a major axis direction of the strobe light emitting tube,
An angle between a reference line passing through the center of the flash tube and a line connecting the center of the flash tube and the end point of the reflector on the protector side is set to a range of 40.7 degrees or more and 44.5 degrees or less. When a distance from the center of the strobe light emitting tube to the reflector end point is L, a tangent line extending from the reflector end point to the inner diameter of the strobe light emitting tube, a center of the strobe light emitting tube and a reflector end point on the protector side. Is 39 / L between the line connecting
(D) An electronic flash device for a camera, characterized in that: 2. The system according to claim 1, wherein a difference between the reference line, a tangent angle of the curved reflecting surface at the end point of the reflector, and an angle of view of a camera is substantially parallel within ± 5 degrees. Strobe device for camera.