WO1994008270A2

WO1994008270A2 - Camera flash unit

Info

Publication number: WO1994008270A2
Application number: PCT/GB1993/002010
Authority: WO
Inventors: Stewart Graham Spinks
Original assignee: Stewart Graham Spinks
Priority date: 1992-09-26
Filing date: 1993-09-27
Publication date: 1994-04-14
Also published as: GB9220383D0; AU4829393A; WO1994008270A3

Abstract

A camera flash unit for use in association with a camera of the type having an integral flash, the unit comprising: a photo sensitive cell (24) having a mounting (25) to mount the cell over said integral flash (12) of said camera (10) to enable activation of the photo sensitive cell (24) by light emitted from the flash (12); and a flash gun (18) positionable at a point remote from the camera, the flash gun (18) being operatively linked to the photo sensitive cell (24) such that activation of the photo sensitive cell (24) by said emitted light will trigger the flash gun (18) to fire.

Description

CAMERA FLASH UNIT

Field of the Invention

The invention relates to a camera flash unit for use in association with cameras having in-built flashes and is primarily, though not exclusively applicable to the problem of so-called red eye.

Background to the Invention

The problem of red eye is one of which all portrait photographers are aware and most notably afflicts the ubiquitous modern day compact cameras having in-built flashes. This phenomenon occurs where the flash is sited too close to the focal axis of the camera lens. Light from the flash passes through the pupil and lens in the eye of the photographic subject to his or her retina. Some of the light is absorbed by the red blood cells and brown pigment behind the retina, whereas the rest is reflected back through the camera lens and recorded on film as a red eye effect.

Conventional cameras lacking in-built flashes tend to be less susceptible to the red eye effect since when they are coupled to an independent electronic flash via a "hot shoe", or similar coupling, the flash generally projects from the camera body by a substantial distance. The problem is even less prevalent where the independent flash is separately hand-held and electronically coupled to the shutter operating system of the camera by a cable. It is, however, unknown or impractical to provide a hot shoe or similar coupling facility on a compact camera of the type having an integral flash since such cameras are designed to minimise the basic size of the camera by excluding peripheral accessories.

The extent of the red eye problem with respect to compact cameras having in-built flashes is particularly well illustrated by a review carried out in the Practical Photography magazine of September 1992. Of 40 compact cameras on test none satisfactorily overcame the problem of red eye because in each case the flash gun was too close to the focal axis of the lens.

Examples of prior patent applications directed toward reducing the red eye effect are given in DE 3 940 654-A (Olympus Optical KK) and DE 2 947 300- A (Agfa-Gevaert AG). The former discloses a flash unit having a pre-flash circuit which provides multiple small flashes to narrow the subjects pupils just before the shutter opens; and the latter discloses an electronic flash fitting for a camera, which fitting pivots on one corner of the camera allowing the flash gun to lie on the top edge or along one side of the camera. In the latter case the spacing from the lens is deemed to be sufficient to at least partially reduce the red eve effect.

Summary of the Invention

According to the invention in its broadest aspect, there is provided a camera flash unit for use in association with a camera of the type having an integral flash, the unit comprising:

a photo sensitive cell having a mounting to mount the cell over a said integral flash of a said camera to enable activation of the photo sensitive cell by light emitted from the integral flash; and a flash gun positionable at a point remote from the camera, the flash gun being operatively linked to the photo sensitive cell such that activation of the photo sensitive cell by said emitted light will trigger the flash gun to fire.

Preferably the photo sensitive cell mounting comprises a cap adapted to fit over the flash unit of a said camera to at least obstruct sufficient of the light emitted from the integral flash to prevent substantially any reflection of the light from the retina of the photographic subject giving rise to red eye effect. Preferably the flash gun is detachably mountable to a said camera by an arm which is suitably articulated.

Advantageously the unit further comprises a body to which the photo sensitive cell is indirectly mounted and from which the arm extends and by means of which the flash gun is mounted to a said camera, the joint between the arm and the body being articulated to allow the arm and flash gun to be collapsed to be stowed in or alongside the body.

Preferably the body of the unit has a storage space for storage of a power supply for the flash gun.

Suitably the flash is secured to a said camera by attachment to a tripod connector of the camera.

The flash unit may incorporate a second arm. in use coupled to the tripod connector and extending along the base of the camera, said second arm being pivotally attached to the flash unit body such that the second arm may be folded against or within the body of the unit when the unit is detached from the camera.

Suitably the flash gun may be folded into a cavity in the body of the unit to protect it from damage when not in use.

This flash unit provides a considerable reduction of the red-eye effect when used with cameras having in-built flashes. The unit folds up to give a small easily portable item which is unobtrusive.

Brief Description of the Drawings

A preferred embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, wherein;

Figure 1 Is a diagrammatic representation of the flash unit when attached to a camera body and extended; and

Figure 2 Is a perspective view of the camera flash unit when detached from the camera body and folded up.

Description of the Preferred Embodiment

Referring to figure 1, there is shown a flash unit of the present invention mounted to a camera body 10 of the type having an integral flash 12. The camera flash unit comprises a body 16 which is detachably mounted to the base of the camera body 10, and extends upwards alongside the flash 1Z, by an arm 15 of the flash unit which is articulated to the body 16 by pivot pins 21. At its uppermost, in use, end the body 16 has a second arm 14 extending therefrom which supports a flash gun 18 at its remote end. The second arm 14 is pivotally mounted by pivot pins 22 to the body 16 and the flash gun 18 is, in turn, pivotally mounted by pivot pins 23 to the remote end of the second arm 14.

The respective pivotal connections between the respective arms 15 and 14 and the body 16 allow the arms 14, 15 to be collapsed into or alongside the units body 16 when the unit is detached from the camera. The articulation of the flash gun 18 to the arm 14 enables it to be stowed within a cavity in the body 16 for greater compactness and protection.

Attachment and detachment of the unit from the camera body 10 is effected by screwing and unscrewing the tripod connector 13 through a socket 2D provided in the arm 15 of the unit.

The unit further comprises a cap 25 adapted to fit over the built-in flash 12 of the camera to substantially obstruct any light that would be emitted from the built-in flash 12 when the built-in flash 12 is fired. This disenables the flash

12 from contributing to production of the red eye effect.

Within the cap 25 there is mounted a photo sensitive cell 24 which is positioned to sense light emitted from the integral flash 12 and is electronically coupled to the flash gun 18 via a cable 17 extending from the cap 25 into the body 16 and up through the arm 14 to the flash gun 18. Power for the flash gun 18 is provided by batteries housed within the body 16.

As illustrated, the cap 25 is joined to the body 16 of the unit simply by the cable 17 and will be held in place, in use, by fastening to the camera body 10 surrounding the integral flash 12. However, by way of alternative, the cap 25 may be held over the integral flash 12 by a further rigid arm extending from the body 16 of the flash unit and which may also be articulated to the body 16 to allow the cap and associated arm to be retracted in toward the body 16.

In operation, the photographer will fit the unit to the camera body 10 as described above, mounting the cap 12 over the in-built flash of the camera 10. Once the photographer has focused upon the photographic subject he will activate the camera as normal with the in-built flash 12 set to operate. The light then emitted from the flash 12 triggers the photo sensitive cell 24 and this, in turn, fires the flash gun 18. By virtue of the substantial separation achievable between the flash gun 18 and the focal axis of the lens of the camera 11 the red eye effect is greatly reduced and may even be wholly avoided.

It will be appreciated by the man skilled in the art that the present invention has benefits which extend beyond solving the problem of red eye in compact cameras having in-built flashes. Wherever it is desired to use an add-on second flash to replace or supplement an in-built flash for more powerful illumination, or for any other reason, the present invention provides a quick and simple way of coupling operation of the second flash to operation of the cameras shutter to obtain the necessary svnchronv.

Claims

1. A camera flash unit for use in association with a camera of the type having an integral flash, the unit comprising:

2. A camera flash unit as claimed in Claim 1, wherein the photo sensitive cell mounting comprises a cap adapted to fit over the flash unit of a said camera to at least obstruct sufficient of the light emitted from the integral flash to prevent substantially any reflection of the light from the retina of the photographic subject giving rise to the red eye effect.

3. A camera flash unit as claimed in Claim 1 or Claim 2, wherein the flash gun is detachably mountable to a said camera by an arm.

4. A camera flash unit as claimed in Claim 3, wherein the arm is articulated.

5. A camera flash unit as claimed in Claim 4, wherein the unit further comprises a body to which the cap is mounted and from which the arm extends and by means of which the flash gun is mounted to a said camera, the joint between the arm and the body being articulated to allow the arm and flash gun to be collapsed to be stowed in or alongside the body.

6. A camera flash unit as claimed in Claim 5, wherein the body has a storage space for storage of a power supply for the flash gun.

7. A camera flash unit as claimed in any of Claims 1-6, wherein the flash unit is secured to a said camera by attachment to a tripod connector of the camera.

8. A camera flash unit as claimed in Claim 7, wherein the flash unit incorporates a second arm, in use coupled to the tripod connector and extending along the base of the camera, said second arm being pivotally attached to the flash unit body such that the second arm may be folded against or within the body of the unit when the unit is detached from the camera.

9. A camera flash unit as claimed in any of Claims 4-8, wherein the flash gun may be folded into a cavity in the body of the unit to protect it from damage when not in use.

10. A camera flash unit as described herein with reference to and as illustrated in the accompanying drawings.