1. Field of the Invention
The present invention relates to a camera arranged to be capable of driving a flash device to move to protruded and stowed positions and to vary the illuminating angle of the falsh device.
2. Description of Related Art
Cameras having built-in flash devices have been variously developed. Meanwhile, efforts to reduce the size of cameras have advanced during recent years. The reduction in size of a camera shortens a distance between the optical axis of a photo-taking lens and the optical axis of a flash device. In addition, the zoom ratio of the photo-taking lens has increased. The increase in zoom ratio tends to cause an increase of a distance between the camera and an object of shooting (such as a person of the like), i.e., the so-called photo-taking distance.
Under the above-stated condition, the reflection of illumination light of the flash device is apt to be made incident on the pupil of a person who is the object of shooting and to be reflected by the retina of the person, thereby causing the so-called red-eye phenomenon. It has become important to suppress the red-eye phenomenon.
To suppress the red-eye phenomenon, some of known cameras are arranged to have a flash device preliminarily emit light or some light source (lamp) other than a flash device emit light in such a way as to contract the pupil of the object (person) immediately before taking a shot.
According to another known method, a camera is provided with the so-called pop-up flash device which is arranged to move its light emitting part away from the optical axis of a photo-taking lens in using the flash device. The flash device is arranged to be stowed inside of the camera body when the camera is not used for photo-taking. Therefore, this method not only effectively suppresses the red-eye phenomenon but also enhances the portability of the camera.
Meanwhile, some of known cameras are arranged to vary the illuminating angle of a flash device according to changes taking place in focal length of a photo-taking lens (the variation of magnification), for efficient use of the light energy of the flash device.
Generally, the illuminating angle of a flash device is considered to be sufficient if it covers the angle-of-view range of the camera. In the case of a camera in which the illuminating angle of a flash device is not variable from one angle to another, the illuminating angle is set to cover an angle of view obtained at the focal length of the wide-angle end position of a photo-taking lens having variable focal lengths. Therefore, in such a case, the illuminating angle of the flash device remains at the angle covering the angle of view of the wide-angle end position even when the focal length of the photo-taking lens is shifted to a telephoto position. Further, the guide number of a flash device is fixed irrespective of the focal length of the photo-taking lens in general. Therefore, the guide number of a flash device is determined by a shootable distance at a telephoto end position where a photo-taking lens generally has a large F-number. As a result, the flash device is allowed to emit light at the illuminating angle covering the photo-taking angle of view obtained at the wide-angle end even in a case where a shot is to be taken at the telephoto end position. In such a case, a portion of the light energy emitted to the outside of the range of the photo-taking angle of view is not used and is thus wasted.
In the case of such a camera that is incapable of varying the illuminating angle of a flash device while the focal length of a photo-taking lens is variable, the flash device must be arranged to have the illuminating angle required on the side of the wide-angle end position and also to meet the requirement for the shootable distance on the side of the telephoto end position of the photo-taking lens. In a case where the zoom ratio of the photo-taking lens is large and the photo-taking lens has a large F-number, the flash device must be arranged to have a large guide number accordingly.
However, a larger guide number requires a larger amount of electric energy. Therefore, the sizes of parts of the flash device such as a charging capacitor, a flash tube, etc., become larger to eventually cause an increase in size of the camera. Besides, when the size of the charging capacitor becomes larger, the length of charging time also increases. Then, in continuously taking shots by using the flash device, the length of time of waiting for completion of charging becomes too long, thereby impairing the quick shooting.
To solve this problem, the illuminating angle of a flash device is arranged to be variable according to the focal length of the photo-taking lens as mentioned above. This method permits efficient use of the light energy for taking a shot at a telephoto position without increasing the size of the camera and without necessitating a long period of time for waiting completion of a charging action.
Further, some of known cameras have a flash device arranged by combining the pop-up type and the type having a variable illuminating angle. However, according to this arrangement, the flash device is arranged in most cases to be manually popped up. For stowing the flash device, a light emitting part which is under an urging force of a spring urging the light emitting part to move in the direction of protruding is held at a stowed position by a lock means. In using the flash device, the user of the camera is required to cause the light emitting part to pop up by unlocking the lock means. The flash device is, therefore, not so good in operability.
Another known camera has a cam arranged to be driven by a gear train provided for driving a photo-taking lens barrel and is arranged to protrude a flash device outward from a camera body by means of the cam and a cam follower. The camera is further arranged to have a light emitting part to be movable back and forth within the casing of the flash device in such a way as to vary an illuminating angle by varying a distance between the light emitting part and a convex lens disposed in front of the light emitting part.
The camera which is thus arranged to protrude the flash device outward from the camera body is provided with a cam plate which is arranged to move along with the movement of the photo-taking lens barrel in the direction of an optical axis. The cam plate is arranged to be used for driving a viewfinder and the light emitting part of the flash device to move together.
In the camera of this kind, however, the moving cam plate and the light emitting part must be arranged to reliably engage each other. This requirement imposes some limitation on the protrudable extent of the flash device and also necessitates the cam plate to be large in size. The arrangement of the camera of this kind thus does not permit efficient space utilization.
Further, the arrangement for driving the viewfinder and the light emitting part by means of a common member imposes some restriction in allocating them. Besides, since the action of moving the flash device between its stowed position and its protruded position and the action of varying the illuminating angle of the flash device necessitate use of interlocking members arranged separately from each other. The arrangement, therefore, increases the number of parts and thus causes an increase in cost.
As regards a mechanism for moving a flash device from its stowed position in the upper part of a camera to the external side of the camera, it is conceivable to connect the flash device to the upper part of a lever member which vertically extends within the body of the camera. The lever member is arranged to be swingable on its lower part, i.e., on an axis extending in parallel with the direction of an optical axis. The flash device is thus arranged to be slidingly driven by swinging the lever member.
However, such a flash-device driving mechanism necessitates a large space within the camera body and thus hinders efforts to reduce the size of the camera.
Another known camera disclosed in Japanese Laid-Open Patent Application No. Hei 10-104696 is arranged to move a flash device between a protruded position and a stowed position in association with the movement of a photo-taking lens barrel in the direction of an optical axis and to vary the illuminating angle of the flash device by moving a flash discharge tube in association with a zooming action of the photo-taking lens barrel.
According to that arrangement, with a driving gear train arranged to move the photo-taking lens barrel in the direction of the optical axis, the photo-taking lens barrel and the flash device are caused to make interlocked motions by distributing a driving force at an intermediate part of the gear train to a cam member which is provided for moving the flash device between the protruded and stowed positions and for moving the flash discharge tube.
However, the cam member is a rotating cam which has a protruded/stowed position driving area and a flash-discharge-tube driving area continuously formed on a cam surface on its periphery to be used according to rotation angles. Therefore, the arrangement is such that the cam member is allowed to make approximately only one turn for a cam follower. Thus, the arrangement imposes a severe restriction on design work in respect of a driving force and a space.
Further, according to that arrangement, power is transmitted to interlocked parts provided for the flash-device protruding and stowing actions even when the position of the cam member is within the flash-discharge-tube driving area. Such power transmission increases a load caused by a spring which is provided for position restriction. Besides, it is difficult to move the flash discharge tube to a sufficient extent. The illuminating angle is, therefore, not sufficiently variable. The guide number is also not sufficiently variable. Therefore, according to that arrangement, it has been hardly possible to obtain an adequate guide number when the photo-taking lens is at a telephoto position.
Meanwhile, in a case where a photo-taking lens barrel is arranged to be driven with a motor and a gear train, gears which are normally in mesh with each other might slip due to deformation or the like when an excessive load is imposed on the photo-taking lens barrel.
Particularly in a case where a worm gear is used at an intermediate point in a reduction gear train, if the photo-taking lens barrel is pushed or pulled in the direction of its optical axis while a motor is at rest, an excessive load is imposed on intermeshing gears with the worm gear in a state of being unable to rotate.
To prevent such an excessive load from being imposed on gears, some of known cameras are provided with a slip mechanism which is arranged to make a slip when an excessive load greater than a predetermined amount of load is imposed on a part of a gear train.
When this slip mechanism works, a gear train from a motor to the slip mechanism and another gear train from the slip mechanism to a photo-taking lens barrel come to deviate from an initial phase relation. With a camera provided with such a slip mechanism, in moving the light emitting part of a flash device or in varying the illuminating angle of a flash device by using a gear train which branches from a photo-taking-lens-barrel driving gear train at an intermediate point of the gear train, the phase of the protruded or stowed position of the light emitting part or that of an illuminating angle of the flash device must be adjusted to the phase of the position in the direction of an optical axis or that of the focal length of a photo-taking lens.
If the above-stated phase deviation takes place while the camera is in operation, there would arise such a problem that the flash device fails to be at the protruded position despite the photo-taking lens barrel being at a photo-taking position, or fails to be not completely set at the stowed position despite the photo-taking lens barrel being at its stowed position.
Further, if a deviation of phase takes place between the focal length position of the photo-taking lens and the illuminating angle of the flash device, either the angle of view of the photo-taking lens cannot be covered by the illuminating angle of the flash device or light of the flash device cannot be completely converged over the whole illuminating angle with the focal length of the photo-taking lens at a telephoto position and thus a prescribed guide number cannot be fulfilled. An under-exposure state tends to result from such a condition.
In accordance with one aspect of the invention, there is provided a camera, comprising a flash light emitting part arranged to be movable between a stowed position and a usage position, a first lever member arranged to swing in such a way as to cause the flash light emitting part to move from the stowed position to the usage position and from the usage position to the stowed position, a second lever member arranged to swing in such a way as to vary an illuminating angle of the flash light emitting part by moving a part of the flash light emitting part, when the flash light emitting part is in the usage position, and a rotating member arranged to rotate according to movement of a lens barrel, wherein a first engaging part arranged to engage the first lever member and a second engaging part arranged to engage the second lever member are formed at the rotating member, so that the size of the camera can be reduced.
The above and other aspects of the invention will become apparent from the following detailed description thereof taken in connection with the accompanying drawings.