JPH01239540A - Zoom type stroboscopic flashing device - Google Patents

Abstract

PURPOSE:To improve a condensing efficiency in the case of tele and to accomplish the reduction in size and in cost by providing an auxiliary reflector which refracts light to an optical axis side integrally with the guiding member of a stroboscopic unit housing on a tele side where a convex Fresnel lens is separated from a reflection unit having a strobe flash tube. CONSTITUTION:The reflection unit 23 and the flash tube 27 are housed in the housing 20 of the stroboscopic unit, which is fitted to a guiding cylinder 36 so that it can be movably supported in an optical axis direction. The auxiliary reflector 32 whose reflecting surface is gradually extended from the guiding cylinder is integrally provided on the leading edge of the guiding cylinder 36. The convex Fresnel lens 25 is fixed to the front opening part of the auxiliary reflector 32 and an interlocking driving mechanism which moves the housing 20 of the stroboscopic unit in the guiding cylinder 36 by interlocking with the alteration of the focal distance of a photographing optical system is also provided. Thus, the condensing efficiency in the case of tele is improved and a zoom type stroboscopic flashing device having a simple inexpensive structure can be obtained. Then the title device can be thoroughly equipped in a miniaturized camera.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a strobe flash device used in cameras and the like, and more specifically to a zoom type strobe flash device that has good light collection efficiency, is compact and inexpensive.

"Prior Art and its Problems" Figures 8a and 8b are vertical cross-sections showing the outline of a conventional zoom type strobe flash device with the irradiation angle at its largest (wide angle) and smallest (tele angle), respectively. It is a diagram. In this flash device, a strobe flash tube (for example, a xenon tube) 17 is arranged inside a reflector 13 having a substantially semi-cylindrical shape so that its longitudinal direction coincides with the reflector 13, and on the front opening side of the reflector 13. A convex Fresnel lens 15, which is a condensing lens, is arranged. The convex Fresnel lens 15 is fixed to the camera body, and the reflector 13 and flash tube 17 can be moved and adjusted integrally with respect to the lens 15. By adjusting the movement of the lever 9, the illumination can be adjusted between wide-angle mode (when reflector 13 is closest to lens 15) and telephoto mode (when reflector 13 is farthest from lens 15), as shown in both figures. It is possible to change the angle.

The conventional structure described above has a problem in that, as shown in FIG. 8b, the light deviates from the reflector 13 and spreads during telephoto mode, making it difficult to obtain a very good condensed state. In order to improve the light collection efficiency in this structure, it is necessary to increase the distance between the reflector 13 and the convex Fresnel lens 15 during telephoto mode, and to increase the size of the convex Fresnel lens 15.

However, such a change has the problem of increasing the size of the entire strobe flash device.

``Object of the Invention'' The present invention has been made to improve the drawbacks of the conventional technology, and is capable of achieving high light collection efficiency during telephoto mode.
Moreover, the object is to provide a zoom type strobe flash device that is small and inexpensive.

"Summary of the Invention" The present invention aims to improve the light collection efficiency particularly on the telephoto side, in order to improve the light collection efficiency on the telephoto side, the light emitted from the reflector is directed toward the optical axis side on the telephoto side where the convex Fresnel lens and the reflector including the strobe flash tube are separated. A small zoom type strobe device is provided with an auxiliary reflector that can be bent, and this auxiliary reflector is provided in association with a guide member of a strobe unit housing having a strobe flash tube and a reflector. That's what I got.

That is, in the present invention, a reflector and a flash tube are housed in a strobe unit housing, and this strobe unit housing is fitted into a guide tube to support the strobe unit so as to be movable in the optical axis direction. 2) An auxiliary reflector that gradually expands from this guide tube is integrated, a convex Fresnel lens is fixed to the front opening of this auxiliary reflector, and the strobe unit housing is used to change the focal length of the photographic optical system. It is characterized by comprising an interlocking drive mechanism that moves the guide cylinder in conjunction with the guide cylinder.

"Embodiment of the Invention" Fig. 1 is an exploded perspective view showing the main parts of an embodiment of the zoom type strobe flash device according to the invention, and Fig. 2 is a front view showing the main parts of the same device without the convex Fresnel lens. It is a diagram.

A reflector 23 is disposed inside the rectangular box-shaped strobe unit housing 20 so as to expand toward the opening side of the housing 20. The reflector 23 has a substantially semi-cylindrical shape in a cross section including the optical axis of the illumination optical system (see FIGS. 4a to 6b). A strobe flash tube (cannon tube) 27 is arranged at the bottom of the reflector 23 so that its longitudinal direction coincides with the reflector 23 .

A guide projection 21 is attached to the upper surface of the strobe unit housing 20, and a driven pin 22 is installed to the lower surface thereof.

Each cylindrical guide tube 36 is provided on the outside of the strobe unit housing 20, and an auxiliary reflecting plate 32 is integrally provided at the tip of each guide tube 36. The inner dimensions of the guide tube 36 match the rear opening of the unit housing, so that the unit housing 32 can slide in the guide tube 36 in close contact. A guide groove 37 is formed on the upper surface of the guide 36 along its longitudinal centerline over approximately the entire length, and the guide protrusion 21 of the unit housing 20 fits into this guide groove 37. On the other hand, an interlocking groove 38 is also formed on the lower surface of the guide tube 36 along its longitudinal center line over almost its entire length, and the driven pin 22 on the lower surface of the unit housing 20 projects from this interlocking groove 38.

The auxiliary reflection plate 32 provided integrally at the tip of the guide tube 36 is
It has a truncated pyramid shape that gradually expands from the guide tube 36, and the convex Fresnel lens 25 is fixed in a sealed state to the front opening thereof. This lens 25 has a concentric Fresnel groove 26 shown in FIGS. 3 to 5b formed on its front surface, that is, the surface opposite to the unit housing 20. As shown in FIGS. This arrangement is preferable in that "vignetting" caused by the grooves 26 is reduced compared to the case where the Fresnel grooves 26 are located on the housing 20 side. Here, "r vignetting" refers to the fact that light no longer contributes to the light-condensing effect due to some kind of obstruction, and details regarding this point can be found in Japanese Patent Application No. 61-55742 (Japanese Unexamined Patent Publication No. 62-2116).
27) can be referred to.

Further, flanges 34 are provided on the four sides of the front opening of the auxiliary reflector 32 in the needle release direction, and these flanges 34 fix the reflector 32 etc. to the casing 50 (see Figure 743) of the strobe flash device. used for

As shown in FIG. 3, which schematically shows the entire strobe flash device, a drive mechanism 40 is disposed inside the device casing 50 alongside the strobe unit housing 20, auxiliary reflector 32, and the like. The drive mechanism 40 uses a cam barrel 42 that changes the focal length of the photographic zoom lens system as a drive source, and the cam W
A cam groove 44 is formed in J42, and the turning lever 4 is inserted here.
6 is engaged. On the other hand, a long groove 48 is bored in the other end of the pivot lever 46, and the unit housing 2 is inserted into the long groove 48.
The driven pin 22 on the lower surface of the lower surface engages.

Figures 4a, 4b; Figures 5a, 5b; and 6
Figures a and 6b are diagrams showing the operation of the zoom type strobe flash device according to the present invention.

As shown in FIGS. 4a, 5a, and 6a, when the reflector 23 is at its widest position, the opening edge of the reflector 23 is connected to the lens 2.
It is used in close proximity to this until it touches 5. At this time, the auxiliary reflector 32 is essentially useless, and therefore, as can be seen from the comparison of the ray diagrams in FIG. 6a and FIG. 8a, the light distribution characteristics obtained here are different from those obtained with the conventional structure. Same as optical characteristics.

On the other hand, as shown in FIGS. 4b, 5b and 6b,
At the maximum telephoto position, the reflector 23 is moved away from the lens 25 until its opening edge is aligned with the rear opening of the auxiliary reflector 32 (the front end of the guide cylinder 36). At this time, the light that leaves the reflector 23 and tries to spread is reflected by the auxiliary reflector 32 and is prevented from spreading, and passes through the lens 25, as shown in the ray diagram in FIG. 6b. Therefore, the light distribution characteristics obtained here have higher light collection efficiency than conventional devices. That is, even if the diameter of the lens 25 is smaller than that of the conventional product and the distance between the reflector 23 and the lens 25 is not large, the light collection efficiency is higher than that obtained with the conventional structure.

Also, between the widest and most telephoto positions, reflector 2
Depending on the position of the reflector 3 with respect to the auxiliary reflector 23, a portion of the light exiting the reflector 23 is reflected by the auxiliary reflector 23, increasing light collection efficiency.

The strobe unit housing 20 is moved by the power transmitted from the cam barrel 42 via the turning lever 46. For example, in the plan views shown in FIGS. 4a and 4b, the strobe unit housing 20 is moved by turning the lever 46 counterclockwise. , the unit housing 20 moves from the wide side to the telephoto side. Of course, the shape of the cam groove 44 of the cam barrel 42 is determined so that the strobe irradiation angle determined by the position of the strobe unit housing 20 corresponds to the focal length of the photographing optical system.

FIG. 7 is an exploded perspective view showing the main parts of another embodiment of the zoom type strobe flash device according to the present invention.

In this embodiment, a cam plate 52 is used instead of the lever 44.
is used so that the driven pin 22 on the lower surface of the strobe unit housing 20 engages with a cam groove 54 formed in the cam plate 52. The cam plate 52 moves in conjunction with changes in the focal length of the photographic optical system, and the shape of the cam groove 54 corresponds to the strobe irradiation angle determined by the position of the strobe unit housing 20 and the focal length of the photographic optical system. It is determined as follows. Since the other parts are the same as those in the first embodiment, the same parts are given the same reference numerals and the explanation will be omitted.

Incidentally, in both of the above embodiments, the strobe unit housing 20
Although the guide protrusion 21 and the driven pin 22 are provided on the upper and lower surfaces of the guide tube 36, they may be arranged on the left and right surfaces, and corresponding grooves may be provided in the guide tube 36.

Effects of the Invention According to the zoom strobe flash device of the present invention, by providing an auxiliary reflector on the outside of the reflector, the light collection efficiency during telephoto mode is increased. Moreover, although the light collection efficiency is increased, the diameter of the convex Fresnel lens can be made smaller than that of conventional products, and there is no need to take a large distance between the reflector and the lens during telephoto mode, so strobe flash It becomes possible to downsize the entire device.

Kira: "The present invention provides a zoom lens with a simple and inexpensive structure because the auxiliary reflector is integrally provided at the tip of the guide tube, and the strobe unit housing having the reflector and flash tube is movably supported within the guide tube. A type strobe flash device can be obtained, and it can be fully mounted on a miniaturized camera.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the main parts of an embodiment of a zoom type strobe flash device according to the present invention, FIG. 2 is a front view showing the main parts of the same device without the convex Fresnel lens, and FIG. FIGS. 4a and 4b are plan views showing the state of the main parts of the device at the widest and most telescopic positions, and FIGS. 5a and 5b are perspective views showing the outline of the entire device. FIGS. 6a and 6b are side views showing the state of the main parts of the device at the widest and maximum telephoto positions, and schematic vertical cross-sectional views showing the states of the main parts of the device at the widest and maximum telephoto positions together with light rays. ,
FIG. 7 is an exploded view showing the main parts of another embodiment of the zoom type strobe flash device according to the present invention, and FIGS. 8a and 8b show the main parts of the conventional zoom type strobe flash device. FIG. 3 is a schematic vertical cross-sectional view showing the camera in a wide-angle mode and a full-telephoto mode. 13--Reflector, 15--Convex Fresnel lens, 17
... Strobe flash tube, 20 - Strobe unit housing, 21 - Guide projection, 22 - Driven bin, 23 -
...Reflector, 25-...Convex Fresnel lens, 26...
Fresnel groove, 27--Strobe flash tube, 32--Auxiliary reflector, 34--Flange, 36--Guide tube, 3
7.38- Rail groove, 40... Drive mechanism, 42-...
・Cam tube, 44・-cam groove, 46・-lever, 48-・
・Groove, 50--Casing, 52...Cam plate, 5
4 ... Cam groove patent applicant Asahi Optical Industry Co., Ltd. Agent Kunio Miura Yoshimi Sasayama Figure 5a Figure 5b

Claims (1)

[Claims] It consists of a reflector whose cross section including the optical axis of the illumination optical system is approximately semi-cylindrical, a strobe flash tube placed at the bottom of the reflector, and a convex Fresnel lens placed on the opening side of the reflector.
A zoom type strobe flash device in which the reflector and the flash tube are movable relative to the lens, including a strobe unit housing that houses the reflector and the flash tube; the strobe unit housing is movable in the optical axis direction. a supporting guide tube; an auxiliary reflecting plate that is integrally provided at the tip of the guide tube and whose reflecting surface gradually expands from the guide tube;
The convex Fresnel lens fixed to the front opening of the auxiliary reflector; and an interlocking drive mechanism that moves the strobe unit housing within the guide cylinder in conjunction with changes in the focal length of the photographic optical system. Features a zoom type strobe flash device.