GB2089522A - Cameras - Google Patents

Abstract

A single reflecting element 3 (e.g. a mirror) is arranged to reflect light received from the field of view through a substantial angle into the lens 2 of a camera 1. The reflecting element is controlled by stabilizing means so that the image in the camera remains substantially steady when angular vibration or tremor is imparted to the camera. In one embodiment, the combination of the camera 1 and the reflecting element 3 is attachable to an operator by means of a harness 5, with the lens of the camera pointing upwardly. <IMAGE>

Description

SPECIFICATION Cameras This invention relates to improvements in or relating to Cameras.

Television, cinematograph and still cameras are often carried by the cameraman instead of being supported on a stand or tripod, in order to allow freedom of movement of the cameraman or of the viewpoint.

In such circumstances any inadvertent movement applied to the camera from hand tremor or body movement results in unsteadiness or blur of the picture. Frequently the cameraman travels in a vehicle and the consequent vibration and buffeting add to the unsteadiness. The unsteadiness or blur of the picture is accentuated by the use of a long focal length lens which provides a narrow field of view. If the camera is fixed to the vehicle the picture degradation is not alleviated.

Devices are available which reduces the unsteadiness of the picture. One such device is the "Steadycam" manufactured by Cinema Products Corporation of Los Angeles which makes use of the natural inertia of the camera by introducing springs between the camera and a harness worn by the cameraman. In this way, movements of the cameraman's body are attenuated so that the camera remains relatively steady in space.

This device has the disadvantage of substantial bulk.

Another such device is the "Arriflex Stabiliser" manufactured by Arnold a Richter of Munich which employs a pair of mirrors in front of the camera lens, one which is controlled by a Gyroscope.

In this second device, the field of view obtainable may be limited by the mirror arrangement.

It is an object of the present invention to provide improved means for stabilising the picture obtained with televison, cinematograph or still cameras and the like when they are subjected to vibration and buffeting. In particular, the invention provides for a compact device which introduces negligible optical degradation but retains the wide field of view normally provided on most portable cameras.

It is a further object of the invention to provide an advantageously elevated viewpoint when required in news gathering and similar roles.

According to this invention, there is provided the combination of a camera and a single reflecting element in which combination the reflecting element reflects light received from the field of view through a substantial angle, preferably about 900, into the camera lens, and is controlled by stabilizing means so that the image in the camera remains substantially steady when angular vibration or tremor is imparted to the combination.

In this arrangement which employs a single reflecting element, the size of element required for a given angle of field of view can be smaller than that required with a system which employs a pair of reflecting elements. It is thus possible to obtain a wide field of view using this arrangement. In addition this arrangement is especially beneficial from the point of view of stabilization, for since the size of the reflecting element is reduced compared to those arrangements having a pair of deflecting elements, the weight of the reflecting element can be reduced, which allows greater stabilization of the image due to the reduction of the inertia.

The stabilizing means may include a gyroscope or an inertial mass. Examples of suitable stabilizing arrangements which may be used to stabilize the image are described in our co-pending published U.K. Application No. 2,036,998A.

The combination preferably includes a viewfinder adapted to display the image received by the camera, and the reflecting element advantageously is a mirror.

For most purposes, the most convenient orientation of the camera will be with its lens pointing upward. In this arrangement, the camera together with its lens and mirror may be carried in front of the cameraman by means of a harness adapted to fit around the body of the cameraman or a shoulder support, the arrangement being such that light from the field of view is collected by the mirror at about shoulder height of the cameraman.

In an alternative arrangement, particular suitable when gathering news in the vicinity of crowds or in hazardous situations, the camera may be carried on the shoulder, still with the lens pointing upward, so that light from the field of view is collected by the mirror from an elevated position above the heads of the cameraman and any surrounding crowd, and possibly above protective cover.

In other special circumstances, such as when a "worm's eye" view is required, or when taking underwater views from a giass-bottomed boat or when taking aerial photographs from an aircraft, the camera may be pointed downward with the mirror disposed below the lens. In other circumstances, it may be more convenient to point the camera horizontally but at right-angles to the axis of the field of view.

When a shoulder support is used, a steadying handle may be provided which extends forwardly and/or downwardly to be gripped by the cameraman and housing one or more controls for the combination.

Naturally, because a single mirror is used to reflect the field of view into the camera lens, a reversal of the scene viewed will take place.

Where the camera is a television camera or film camera, this may be compensated by reversing either the line or frame scan normally employed within the camera.

By way of example only, two specific embodiments of apparatus constructed in accordance with this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of a first embodiment of this invention, and Figure 2 is a diagrammatic representation of a second embodiment of this invention, and Figure 3 is a diagrammatic representation of a suitable form of stabilizing arrangement for use in the embodiments of Figures 1 or 2.

Referring initially to Figure 1, a camera 1 and its associated lens 2 are pointed upward to receive light from a scene viewed after reflection by a stabilizing mirror 3. The stabilizing mirror 3 is housed in a casing 3' and mounted in gimbals to be controlled by a gyroscope or an inertial mass to stabilize the image seen by the camera 1. The mirror mounting may include a steering device to cause the mirror 3 to react to slow steering actions applied to the camera, yet not to tremor and vibration motion, so that intentional movements of the camera allow the viewed scene to the changed. Examples of suitable stabilizing devices of this kind are described in our copending U.K. published Patent Application No.

2,036,998A. If a gyroscope is used, its motor may be driven by electricity drawn from the camera supply or from a battery housed in the mirror unit's casing 3'.

Camera 1, lens 2, and casing 3' are attached to the front portion of a body harness 5, so that the casing 3' is at approximately shoulder height of the cameraman and supports on its rear portion ancillary equipment 6 such as a video tape recorder and/or batteries. The ancillary equipment 6 helps to balance the weight of the equipment attached to the front portion of the harness.

A video viewfinder 4 is attached to the outside of casing 3' and oriented in a convenient position before the cameraman's eye. The equipment is operated by controls located on the camera 1, lens 2, and casing 3'. Cables 7 interconnect the camera 1, viewfinder 4 and ancillary equipment 6.

The casing 3' preferably includes a window through which the scene is viewed to prevent contamination of the mirror 3 and lens 2. The casing 3' may be detached from the lens 2 and the camera and view finder 4 may then be removed from the harness 5 and casing 3' respectively to allow conventional use of the camera.

Referring to the embodiment of Figure 2, certain parts are similar to those of the embodiment of Figure 1; such parts are given like reference numerals and will not be described in detail again. In this second embodiment, the camera 1, and associated lens 2, are pointed upward to receive light from a scene viewed after reflection by a stabilizing mirror 3. The barrel for the lens 2 supports a casing 3' for the stabilizing mirror 3, and the camera is attached to a harness 5 which passes over the shoulders of a cameraman, the arrangment being such that the stabilizing mirror 3 is positioned above the head of the cameraman. A control arm 8 extends forwardly and downwardly from the harness 5 to a convenient position for gripping by the cameraman.Either a single arm 8, or a pair of arms 8, one for gripping by each hand of the cameraman respectively, may be provided, as the particular arrangement dictates. A video view finder 4 is attached by an arm to the camera 1 and is positioned before one of the cameraman's eyes.

The various controls for the camera 1, lens 2, and stabilizing mirror 3 may be mounted on the control arm 8. Such controls may include lens focus, aperture and zoom controls, video tape recorder start/stop, stabilizing mirror caging control etc. A battery may be incorporated in the harness 5 or incorporated in the camera 1. The video tape recorder may be attached to the rear portion of the harness or be remotely located.

In both embodiments, a single mirror is used to reflect the field of view into the camera lens. A reversal of the scene thus take place about one axis and it may therefore be necessary to reverse the picture to compensate for this before presenting it to an observer. If the camera is a normal television camera, this may be done by reversing the direction of scanning about the appropriate axis. Alternatively, the direction of scanning on the display tubes may be reversed.

Such reversal can simply be carried out by reversing the connections to the camera or display tube scanning coils or deflection plates, by means of a switch especially provided for the purpose.

If the camera is a cinematograph or still photographic camera, the reversal of the pictures may be carried out be reversing the film in the viewing device or projector or, if a negative/positive system is used, by reversing the negative when printing the positive film.

If the camera is a television camera, the viewfinder includes a television display tube is positioned so that the display is before the cameraman's eye. If the camera is a cinematograph or still photographic camera the optical viewfinder normally fitted may be ignored and a television camera, adapted to receive its view through the cinematograph or still photographic camera lens, and a television viewfinder may be used, with the display tube conveniently positioned before the cameraman's eye. Such television systems are available for use with professional type cinematograph cameras, (e.g. CINEVID obtainable from Cinema Products Corporation, Los Angeles, California, U.S.A.).

Alternatively, a separate optical viewfinder may be attached to the camera.

In either embodiment, the video signal may be transmitted to a receiving station by cable or radio as an alternative to local recording.

While the invention is specifically described with reference to the use of portable cameras, it may also be used with cameras mounted on moving vehicles in which case the harness or shoulder support would be replaced by a fixed or steerable mount.

Referring now to Figure 3, there is shown a form of stabilizing arrangement suitable for use with either of the above embodiments.

The stabilizing arrangement comprises a gyroscope rotor 10 fixed to a shaft 11 one end of which is coupled by way of two universal joints 12 to the output shaft of an electric motor 13.

The motor 13 is fixed to a frame 9 and is energized by a battery (not shown). The other end of the shaft 11 is supported via bearings (not shown) within a mounting block 14. The block 14 is mounted between the arms of forked gimbal member 1 5 such that the block 14, along with the gyroscope rotor 10, can turn about the axis X with respect to the gimbal member 1 5. The member 1 5 has two stub-shafts 1 6 fixed thereto, which stubshafts are supported by bearing blocks 1 7 fixed to the frame 9 such that the member 1 5 along with the block 1 4 and the gyroscope rotor 10, can turn about the axis Y with respect to the housing 9.The ends of the arms of the forked gimbal member 1 5 support the mirror 3 between them such that the mirror can turn about an axis Z parallel to axis X. A link member 1 8 is pivotably coupled to the mirror 3 and the mounting block 14 so as to control movements of the mirror about axis Z in dependence upon the angular movement of the block 14 relative to the member 1 5. If the stabilizing arrangement moves, the gyroscope rotor 10 tends to maintain its position in space, i.e.

it moves about axes Y and X in relation to the housing 9. This relative movement is transmitted to the mirror 3 such that the light ray portion A remains fixed relative to the housing 9.

The shaft 11 projects from the forward end of block 14 and carries a disc 11 a. A leaf spring member 1 9 is fixed to the frame of and extends in front of the disc 1 a and carries there a friction pad 20. When the case is rotated intentionally in order to steer the sightline, i.e. to change the direction in which the camera is pointing, the friction pad 20, which in its central position is just clear of the rotating disc 11 a rotates about the axes X and/or Y and touches the disc. For example, if the case and pad are tilted downward relative to the disc, the disc will touch the pad at a position below the disc's centre. Because the disc is rotating, the pad will apply a frictional force to the surface of the disc.This force results in a torque being applied to the rotor about the axis X which begins to precess the rotor downward about the axis Y to follow the movement of the case, according to the known rules of gyroscope motion.

Because of the angular momentum of the rotor and the characteristics of the pad and spring, the system forms a low-pass frequency filter which reacts to slow steering actions but not to tremor and vibration and only if the case's movement is sustained will there be time for the rotor to catch up with the case.

Thus, the pad 20 and disc 1 a form a steering device which allows movements of the camera and stabilizing device greater than those associated with vibration and tremor, i.e.

intentional movements of the camera to change the scene viewed. Alternative steering means may be employed instead of the disc and pad. For example, a steering device is known which operates magnetically to apply a precessing torque to the rotor.

Claims (14)

1. The combination of a camera and a single reflecting element in which combination the reflecting element reflects light received from the field of view through a substantial angle into the lens of the camera and is controlled by stabilizing means so that the image in the camera remains substantially steady when angular vibration or tremor is imparted to the combination.

2. The combination as claimed in Claim 1, wherein the reflecting element reflects light received from the field of view through an angle of approximately 900.

3. The combination as claimed in Claim 1 or Claim 2, wherein the stabilizing means include a gyroscope.

4. The combination as claimed in Claim 1 or Claim 2, wherein the stabilizing means include an inertial mass.

5. The combination as claimed in any of the preceding Claims, wherein the reflecting element is a mirror.

6. The combination as claimed in any of the preceding Claims, which further includes a viewfinder arranged to display the image.

7. The combination as claimed in any of the preceding Claims, wherein the camera is of the television type and the direction of either the line or the frame scan is reversed to that conventionally employed.

8. Camera apparatus for carriage by an operator said apparatus including the combination of a camera, and a single reflecting element, the reflecting element reflecting light received from the field of view through a substantial angle into the lens of the camera and being controlled by stabilizing means so that the image in the camera remains substantially steady when angular vibration or tremor is imparted to the combination, and carrying means secured to the combination so that in use, the camera lens points generally upwardly.

9. Camera apparatus as claimed in Claim 8, wherein the carrying means comprise support means attachable to the operator's body.

10. Camera apparatus as claimed in Claim 9 which further includes viewfinder means arranged to display the image received by the camera at a location readily viewable by the operator.

11. Camera apparatus as claimed in Claim 9 or Claim 10, wherein the reflecting element receives 'ight from the field of view from a level higher than that of the operator's eye level.

12. Camera apparatus as claimed in any of Claims 9 to 11, wherein the support means pass over the shoulder of a user.

13. Camera apparatus as claimed in any of Claims 8 to 12 wherein the stabilizing means includes means for applying a force to the reflecting element to cause it to follow an intended change in the direction of the field of view.

14. The combination of a camera and a single reflecting element, substantially as hereinbefore described, with reference to, and as illustrated in, the accompanying drawings.

1 5. Camera apparatus substantially as hereinbefore described with reference to, and as illustrated in, any of the accompanying drawings.