GB2026720A

GB2026720A - Electronic Flash Device

Info

Publication number: GB2026720A
Application number: GB7923968A
Authority: GB
Original assignee: Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
Current assignee: Osram GmbH
Priority date: 1978-07-10
Filing date: 1979-07-10
Publication date: 1980-02-06
Also published as: IT7953403V0; GB2026720B; IT7968422A0; FR2431090B1; FR2431090A1; IT1119019B

Abstract

An electronic flash device comprises a casing (1, 2, 3), a manually pivotable reflector (6) in the casing (1, 2, 3) pivotable abouts its focal axis (A) and divided into at least two parts (6'', 6', 6''') transverse to its axis (A) without the provision of dividing walls, a linear light source (5) lying on the focal axis (A) of the reflector (6), at least one part (6', 6''') being selectively pivotable about its focal axis (A) relative to the other part (6'') such that the light from the light source (5) can be transmitted in two different directions separately or at the same time, electrical operating equipment for the light source (5) in the casing and mechanical and electrical connection means (8) for connection to a camera. The device provides direct, indirect, or direct and indirect illumination simultaneously. <IMAGE>

Description

SPECIFICATION An Electronic Flash Device The invention relates to an electronic flash device. One such device comprises a casing, a linear light source in the casing and a reflector associated with the light source and manually pivotable, the light source lying on the focal axis of the reflector, electrical operating devicds in the casing and a conventional attachment device for attachment to a camera. Electronic flash devices of this type known up till now and commercially available are designed so the user has only the choice of either direct scene illumination exclusively or indirect scene illumination. On the other hand however it is not possible for the user to achieve, with such a device, the sort of image quality which is particularly noticeable for the absence of sharply defined shawdows because of direct and simultaneously indirect illumination of the subject.

Consequently, the invention seeks to create an electronic flash device which offers the ability to provide direct and indirect illumination of the subject simultaneously.

This is a facility which has normally only been available to professional photographic studios owing to the high cost of equipment-more particularly because it has required studio facilities. Thus the non-professional user will even in his own pictures in future be able to avoid sharply defined shadows in favour of soft shading or shade transitions.

According to the invention there is provided an electronic flash device comprising a casing, a manually pivotable reflector in the casing pivotable about its focal axis, a linear light source lying on the focal axis of the reflector, electrical operating equipment for the light source in the casing, and mechanical and electrical connection means for connection to a camera wherein the reflector is divided into at least two parts transverse to its axis without the provision of dividing walls, at least one part being selectively pivotable about its focal axis relative to the other parts, the arrangement being such that the light from the light source can be transmitted in two different directions separately or at the same time.

Preferably the light source and reflector are contained in a cylindrical sleeve casing closely surrounding the reflector, the cylindrical sleeve casing being connected to a generally rectangular casing part containing the electrical operating equipment for the light source.

The linear light source is preferably horizontal in the position of use of the device. The reflector associated with the light source or its reflector parts may be trough-shaped. The trough-shaped reflector parts lying adjacent each other and following on directly from each other are preferably not separated from each other by means of intermediate walls. Only side parts limiting the reflector as a whole may be provided.

All of the reflector parts may be pivoted about the longitudinal axis of the light source. A mechanism may be provided which makes it possible for either only a first reflector part or a first group of reflector parts respectively to be pivoted or for all of the reflector parts to be pivoted jointly.

The rectangular casing may comprise two rectangular parts which continue the cylindrical sleeve casing containing the reflector on opposite sides thereof and may be pivotable with respect to each other about an axis which coincides with the axis of the light source and of the cylindrical sleeve casing and of the focal line of the reflector.

One casing part may be connected to a first reflector part or a first group of reflector parts so that it pivots this part or group with respect to the second reflector part or the second group of reflector parts when both casing parts are pivoted with respect to each other, while the second reflector part or the second group of reflector parts may remain in its position with respect to the second casing part.

A control device may be provided which is able to take up two positions, in one position the second reflector part or the second group of reflector parts may be connected to the second (and in use lower) casing part and in a second position of the control device the second reflector part or the second group of reflector parts may be isolated from the lower casing part and connected to the first (or in use upper) casing part. The longitudinal axes of the lower and upper casing parts may be aligned in the postion in which all reflector parts have their reflecting surfaces in alignment This is the case when there is exclusively direct illumination of the subject. The common main direction of radiation of all of the reflector parts is perpendicular to the longitudinal axes of the two casing parts in this postion.After the casing parts have been pivoted with respect to each other the main direction of radiation of the first reflector part or the first group of reflector parts may always include a right angle with the longitudinal axis of the upper casing part, while the main direction of radiation of the second reflector part or the second group of reflector parts may include a right angle, either with the longitudinal axis of the lower casing part or with that of ther upper casing part. In the first case this corresponds to direct and simultaneously indirect illumination. In the later case it relates exclusively to indirect illumination of the subject.

Preferably the reflector of the device is divided into three parts by two sections perpendicular to the focal line of the reflector. The two outer parts which are of equal length axially may be jointly pivotable while the middle part either remains in its non moving position when the two outer parts are pivoted or is also pivoted jointly with the outer reflector parts. The two rectangular parts may be kept approximately equal in their outer dimensions so that the cylindrical sleeve casing gives the entire device the optical impression in its outward appearance that it has taken up a centred position.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which Figure 1 shows, in perspective view, one form of flash device in accordance with the invention in a position for providing both direct and indirect illumination; Figure 2 is a front view of the device of figure 1 showing the device set for direct illumination only; Figure 3 is a view similar to figure 1 but with the device set up for indirect illumination only; Figure 4 shows, in Catesian co-ordinates, the region in which the curvature of the reflection surface of the reflector parts of the reflector of the device in accordance with Figures 1 and 2, 3, 5, 6 lines as well as the preferred path of curvature; Figure 5 is a rear view of the device of figures 1 to 3, and Figure 6 shows a further embodiment of the flash device.

Two rectangular casing parts are designated 1 and 2 and contain electrical operating devices for the flash device. These casing parts comprise plastics material as does a cylindrical sleeve casing 3. The casing parts 1 and 2 are dimensioned so as to be substantially the same.

They are pivotable about an axis A. This axis A is the central axis of the cylindrical sleeve casing 3 and the central axis of the single light source of the device, a linear flash tube 5, and identical to the focal axis of a reflector 6 associated with this flash tube 5. This reflector 6 is subdivided into two or more parts, here preferably into three trough-shaped reflector parts 6', 6", 6"', which reflector parts lie adjacent each other along the longitudinal extent of the flash tube 5 and follow on directly from each other, whereby intermediate walls physically separating them are not present as their presence would have a disadvantageous effect on the desired light distribution characteristics. Only side walls 7 limiting the subdivided trough-shaped reflector 6 as a whole are provided. The side walls 7 are arranged pointing obliquely outwardly.The reflector parts 6', 6", 6"' may be pivoted about the axis of flash tube 5, i.e. axis A. The mechanism for pivoting is substantially housed in the cylindrical sleeve casing 3. By moving the casing part 1, relative to the casing part 2 about the common axis, the mechanism is actuated, the casing part 1 then acting as the pivot handle. According to the position of the reflector parts it is possible to illuminate (a scene) either directly, indirectly or simultaneously indirectly and directly. If solely direct illumination is desired,, all of the reflector parts are arranged in the starting position (Figure 2) and point their reflector openings and thus their directions of main radiation straight forwards on to the subject to be photographed.If solely indirect illumination of a subject is required all of the reflector parts are pivoted about an angle of 600 such that their reflector opening point obliquely upwards as shown in Figure 3. In order that the middle reflector part 6" comes into this position a stop knob or lever arranged on the rear side of the device is displaced sideways before pivoting, the knob or lever releasing this reflector part for pivoting. On the other hand if simultaneously direct and indirect illumination of the subject is sought after, a reflector position as shown in Figure 1 is taken up.Only the two outer reflector parts 6' and 6"' are rotated with respect to their starting position while the middie reflector part 6" on the other hand, point unchanged towards the front. in the pivoted position the longitudinal axes L1 of the casing part 1 and L2 of the casing part 2 are at an angle to each other. In the case of exclusively direct illumination these two axes form a straight line. In order to bring about the individual reflector positions, the two outer reflector parts 6' and 6"' are connected to the casing part 1. The reflector part 6" may be connected optionally to casing part 1 or associated with casing part 2.

The overall dimensions of the whole of the reflector 6 amount to approximately 24.1 2x54.2 mm in the plane of its outlet opening. The angle of its light beams for half maximum intensity is thus 2 a=650 horizontally and 2 a=500 vertically. The width a bf the reflector part 6" is constant at approximately 10 mm. The width b of tthe reflector parts 6', 6"' on the other hand increases from the trough bottom of the reflector towards the light outlet opening because of the inclined angle of the side walls 7. While the width b of the two reflector parts 6', 6tn is approximately 1 5 mm at the trough bottom of the reflector, in the plane of the light outiet opening of the reflector it is approximately 22 mm.The ratio of the width a of a reflector part 6" to the sum of the widths b of the reflector parts 6' 6tn is 1:3 at the trough bottom of the reflector. A portion of approximately 40 mm in length of the illumination' coiumn produced by the light source 5 is utilized, approximately three-quarters of this column being used for the indirect portion in each case where there is simultaneously direct and indirect illumination of the subject. The ratio of the width a of the reflector 68 to the sum of the widths b of the reflectors parts 6'. 6"' is 1:4.4 in the plane of the light outlet opening.The curvature of the reflection surface of the reflector parts 6' 6", 6xn lies in a region R (hatched) (Figure 4) limited by two curves A, B, in which range the following is true: A: y2-1 3 4x-0.3722x2 where O < y < 12.3 and B: y2-1 8x-0.5233x2 where O < y < l 1 shown in Cartesian co-ordinates in Figure 4.

The curve of the reflection surface of the reflector parts preferably comprises three curved portions I, II, III which are successive, provide a continuous curve and lie in this range whereby portion I corresponds to the y2=1 5.4x-0.0675x2 where O < y < 4, portion II corresponds to the equation y2=14.6x--0.4148x2 where 4 < y < 9, and section III corresponds to equation Y+ 1 2.6x-0.268 1 x2 where 9 < y < 12.06.

A curved light outlet window 4, which permits the passage of radiation screens the lamp reflector area from its surrounding. This window has light-scattering elements, for example axial corrugations. A base 8 moulded on to the device serves for electrical and mechanical connection to a camera.

The stop means which retains the middle reflector part 6" as required or frees it for pivoting by means of its lateral displacement is shown in Figure 5 and designated 9, Figure 5 showing the rear of the electronic flash device in accordance with the invention. The part 6n remains in its starting position in the knob position associated with the symbols while the outer reflectors parts 6' and 6n may be pivoted. If the knob is pushed towards the right to stop below the symbol t then the reflector part 6" may at the same time also be pivoted with the parts 6' and 6'n. Symbol indicates direct and silmultaneously indirect illumination and b indicates solely indirect illumination. An aperture table is indicated at 10.

As an alternative, the casing part 1 may be omitted (Figure 6.) A handle for actuating the mechanism in the cylindrical sleeve casing 3 for the purpose of pivoting the reflector parts 6', 6", 618 with respect to casing part 2 would then be a slightly convex disc 11. If the casing is black, then the disc may be coloured green for example.

Claims

1. An electronic flash device comprising a casing, a manually pivotable reflector in the casing pivotable about its focal axis, a linear light source lying on the focal axis of the reflector, electrical operating equipment for the light source in the casing, and mechanical and electrical connection means for connection to a camera wherein the reflector is divided into at least two parts transverse to its axis without the provision of dividing walls, at least one part being selectively pivotable about its focal axis relative to the other part, the arrangement being such that the light from the light source can be transmitted in two different directions separately or at the same time.

2. An electronic flash device according to claim 1, wherein the light source and reflector are contained in a cylindrical sleeve casing closely surrounding the reflector, the cylindrical sleeve casing being connected to a generally rectangular casing part containing the electrical operating equipment for the light source.

3. An electronic flash device according to claim 2, wherein, in use, the linear light source is horizontal, the reflector associated therewith is trough-shaped with no subdividing walls but with end walls which serve to delimit the reflector as a whole.

4. An electronic flash device according to claim 2 or 3, wherein all reflector parts may be pivoted about the longitudinal axis of the light sources as a pivot axis and a mechanism is provided for enabling selective pivotting of only a first reflector part or a first group of reflector parts or to pivot all of the reflector parts together.

5. An electronic flash device according to claim 2, 3 or 4, wherein the rectangular casing comprises two rectangular parts which extend from the cylindrical sleeve casing containing the reflector on opposite sides thereof and which are pivotable with respect to each other about an axis which coincides with the axis of the light source, the axis of the cylindrical sleeve casing and the focal axis of the reflector; and wherein one casing part has a first reflector part or a first group of reflector parts connected to it so that it or they pivot with respect to the second reflector part or second group of reflector parts when both casing parts are pivoted with respect to each other while the second reflector part or second group of reflector parts is selectively retainable in its position with respect to the second casing part.

6. An electronic flash device according to claim 5, wherein a control device which can take up two positions is provided on one casing part, in a first position of the control device, the second reflector part or second group of reflector parts is connected to the second casing part; and in a second position of the control device the second reflector part or the second group of reflector parts is released from the lower casing part and is connected to the upper casing part.

7. An electronic flash device according to claim 5 or 6, wherein, when the longitudinal axes of the two casing parts coincide, all the reflector parts are in alignment for light radiation perpendicular to the longitudinal axes of both casing parts in order to provide direct illumination of the subject while after the casing parts have been pivoted with respect to each other, the main direction of radiation of the first reflector part or the first group of reflector parts always includes a right angle with the longitudinal axis of its associated casing part, while the main direction of radiation of the second reflector part or the second group of reflector parts selectively includes a right angle, with the longitudinal axis of either casing part.

8. An electronic flash device according to any one of claims 1 to 6, wherein the reflector is divided into three parts by two sections perpendicular to its focal axis and the two parts which are of equal length and are the outer parts in an axial direction can be pivoted together while the middle part is retainable in a non-moving position if desired during pivoting of the two outer reflector parts or can be pivoted jointly with the outer reflector parts.

9. An electronic flash device according to claim 8, wherein the reflector or its reflector parts lying adjacent each other and attached directly to each other have a curvature of their reflecting surface which lies in a range which is limited by the curves: A: y2- 1 3.4x-0.3722x2 where O < y < 12.3 and B: y2=1 8x -0.5233x2 where O < y < 1 1.

10. An electronic flash device according to claim 9, wherein the path of curvature comprises three curved portions which are successive portions and lie in the said range whereby the first portion corresponds to the equation y2=1 5.4x-0.0675x2 where O < y < 4, the second portion corresponds to the equation y=146x-0.4148x where 4 < y < 9, and the third portion corresponds to the equation y2=12.6x--0.2681x2 where 9 < y < 12.06.

11. An electronic flash device according to any one of claims 1 to 9, wherein the cylindrical sleeve casing has a window provided with lightscattering elements.

12. An electronic flash device according to claim 10, wherein the light-scattering elements are axial corrugations.

13. An electronic flash device according to claim 8, 9, or 10, wherein the ratio of the width of the middle reflector part to the sum of the widths of the end reflector parts is 1:3 at the base or trough bottom of the reflector and 1:4.4 in the plane of the light outlet opening.

14. An electronics flash device substantially as described herein with reference to the drawings.