The present invention relates to an auxiliary lighting device of a camera, and specifically relates to an auxiliary lighting device, which can be preferably incorporated in such a camera that is capable of capturing a close-up image.
Conventionally, a camera has generally incorporated an auxiliary lighting device, so that a good captured image can be obtained by employing the auxiliary lighting device for the image capturing operation, even when the image is captured in a dark environment or under a backlight condition.
A light irradiating section of the auxiliary lighting device incorporated in the camera is constituted by a light emitting member formed in substantially a cylindrical shape, such as a Xenon tube, etc., and a reflector on which light emitted from the light emitting member are reflected toward the subject. Further, the reflector is constituted by a circumferential wall section formed around the cylinder axis of the light emitting member and two sidewall sections, which intersect the cylinder axis of the light emitting member and oppose to each other. In the conventional auxiliary lighting device for general purpose, cross sectional shapes of the reflector, being orthogonal to the axis direction of the Xenon tube, have been the same at any positions on the axis direction of the Xenon tube, and the angle of one of the two sidewall sections versus the surface orthogonal to the Xenon tube has been the same as that of another one of the two sidewall sections.
Departing from such the light irradiating section in the conventional auxiliary lighting device for general purpose as mentioned in the above, for instance, Patent Document 1 sets forth an auxiliary lighting device, in which the shape of the reflector is formed in such a manner that at least a cross sectional shape of the reflector at a specific position, being orthogonal to the axis direction of the Xenon tube, is different from those at any positions other than the specific position, or the cross sectional shape of the reflector continuously changes along the axis direction of the Xenon tube, or the cross sectional shape of the reflector is established as a series of discontinuous shapes in the axis direction of the Xenon tube.
[Patent Document 1]
Subject to be solved by the Invention
When incorporating the light irradiating section of the auxiliary lighting device in conventional cameras, although the auxiliary lighting device is disposed just above the optical axis of the photographic lens in a state of the horizontal position photography in some conventional cameras, the auxiliary lighting device is generally disposed at such a position that is apart from the optical axis of the photographic lens by shifting it toward an inclined upper-left direction or toward an inclined upper-right direction from the optical axis in most of the conventional cameras.
On the other hand, the photographic lens, to be incorporated in an electric camera in which analogue signals, acquired by photo-electronically converting the captured image of the subject, is further converted into digital image data, and then, predetermined image-processing operations are applied to the digital image data, so as to store the processed digital image data into the recording medium, is generally capable of conducting a close-up photography to such an extent that some electric camera can capture an image of the subject close to the front surface of the lens at a position separating from the subject only by several centimeters.
However, when the camera approaches the subject such the extent as mentioned in the above, there has been a problem that, due to the positional deviation between the light irradiating section of the aforementioned auxiliary lighting device and the optical axis of the photographic lens, an amount of light irradiated onto one side potion of the subject, to which the auxiliary lighting device does not oppose directly, becomes short, resulting in unevenness of exposure amount on the captured image.
Further, in recent years, well known is the bended optical system in which the optical axis is bended in a direction substantially parallel to the front surface of the camera by disposing reflecting member within the photographic lens. In the camera equipped with the abovementioned photographic lens, since the front surface of the lens is substantially equivalent to the front surface of the camera, the aforementioned problem of the unevenness of exposure amount when conducting the close-up photography is getting into more serious situation.
The light irradiating section of the auxiliary lighting device described in the aforementioned Patent Document 1 relates to the shape of the reflector when employing such a camera design concept that the aperture section of the reflector, normally shaped in a rectangular, is not protruded outside from the camera. Accordingly, the irradiating section described in the aforementioned Patent Document 1 cannot be a countermeasure for solving the problem of the unevenness of exposure amount.
In view of the abovementioned problem, an object of the present invention is to provide an auxiliary lighting device, which makes it possible to reduce the unevenness of exposure amount on the image captured in the close-up photographing mode, even if the auxiliary lighting device is disposed at such a position that is apart from the optical axis of the photographic lens by shifting it toward an inclined upper-left direction or toward an inclined upper-right direction from the optical axis.
Means for Solving the Subject
The abovementioned object is attained by the following structures.
(1) An auxiliary lighting device that is incorporated in a camera and is disposed at a position being apart from an optical axis of a photographic lens for capturing a subject, and that comprises a light irradiating section constituted by a reflector to reflect light emitted from a light emitting member, which is shaped in substantially a shaft, toward the subject, the auxiliary lighting device characterized in that the reflector includes a circumferential wall section formed around the shaft of the light emitting member and two sidewall sections, which intersect the shaft of the light emitting member and oppose to each other, and angles, formed between the two sidewall sections included in the reflector and surfaces orthogonal to the light emitting section, are set at values being different from each other.
(2) The auxiliary lighting device, recited in item 1, characterized in that one of the angles, formed between one of the two sidewall sections, located at a position far from the optical axis of the photographic lens, and one of the surfaces orthogonal to the light emitting section, is smaller than another one of the angles, formed between another one of the two sidewall sections, located at a position near to the optical axis of the photographic lens, and another one of the surfaces orthogonal to the light emitting section.
(3) The auxiliary lighting device, recited in item 1 or 2, characterized in that, when angle a represents one of the angles, formed between one of the two sidewall sections, located at a position far from the optical axis of the photographic lens, the angle a fulfills the equation of,
(tan−1(a/b)−tan−1((D−a+c)/(r+b−D tan θ)))/2≦α≦(tan−1(a/b)−tan−1((D−a+c)/(r+b+D tan θ)))/2,
where a: a distance between a position of the light emitting section and a leading edge of one of the two sidewall sections in a direction of the optical axis of the photographic lens;
b: a distance between a center of the light emitting section and the leading edge of one of the two sidewall sections in a direction orthogonal to the optical axis of the photographic lens,
c: a distance between the position of the light emitting section and an intersect of long side light bundles in the direction of the optical axis of the photographic lens,
r: a distance between the optical axis of the photographic lens and the center of the light emitting section in the direction orthogonal to the optical axis of the photographic lens,
D: a distance between a photographic position in a most close-up distance photographing mode and the intersect of the long side light bundles in the direction of the optical axis of the photographic lens, and
θ: a half angle of view in a long side direction.
(4) An auxiliary lighting device that is incorporated in a camera and is disposed at a position being apart from an optical axis of a photographic lens for capturing a subject, and that comprises a light irradiating section constituted by a reflector to reflect light emitted from a light emitting member, which is shaped in substantially a shaft, toward the subject, the auxiliary lighting device characterized in that the reflector includes a circumferential wall section formed around the shaft of the light emitting member and two sidewall sections, which intersect the shaft of the light emitting member and oppose to each other, and the light irradiating section is so constituted that an intersecting angle of one of the two sidewall sections included in the reflector, located at a position at which a distance from the optical axis of the photographic lens is greater than that for another one of the sidewall sections, and the light emitting member, is changeable.
(5) The auxiliary lighting device, recited in item 4, characterized in that the intersecting angle of one of the two sidewall sections included in the reflector, located at the position at which the distance from the optical axis of the photographic lens is greater than that for the other one of the sidewall sections, and the light emitting member, is changed corresponding to a subject distance.
(6) The auxiliary lighting device, recited in item 1 or 2, characterized in that, when angle α represents one of the angles, formed between one of the two sidewall sections, located at a position far from the optical axis of the photographic lens, the angle α is changed so as to fulfill the equation of,
(tan−1(a/b)−tan−1((D−a+c)/(r+b−D tan θ)))/2≦α≦(tan−1(a/b)−tan−1((D−a+c)/(r+b+D tan θ)))/2,
where a: a distance between a position of the light emitting section and a leading edge of one of the two sidewall sections in a direction of the optical axis of the photographic lens;
b: a distance between a center of the light emitting section and the leading edge of one of the two sidewall sections in a direction orthogonal to the optical axis of the photographic lens,
c: a distance between the position of the light emitting section and an intersect of long side light bundles in the direction of the optical axis of the photographic lens,
r: a distance between the optical axis of the photographic lens and the center of the light emitting section in the direction orthogonal to the optical axis of the photographic lens,
D: the subject distance, and
θ: a half angle of view in a long side direction.
According to the invention recited in any one of items 1-3, it becomes possible to provide an auxiliary lighting device to be incorporated in a camera, which makes it possible to reduce unevenness of exposure amount on a captured image when conducting the close-up photographing operation, even if the light irradiating section of the auxiliary lighting device is disposed at a position shifted from the optical axis of the photographic lens.
According to the invention recited in any one of items 4-6, it becomes possible to provide an auxiliary lighting device, which has such an appropriate light distribution characteristic that makes it possible to reduce unevenness of exposure amount caused by the parallax over a range of far to near distance (or Tele to Wide photographing mode), even if the light irradiating section of the auxiliary lighting device incorporated in the camera is disposed at such a position that is shifted from the optical axis of the photographic lens.
Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which:
The embodiments of the present invention will be detailed in the following. However, the scope of the present invention is not limited to the embodiments described in the following.
As shown in
Numeral 52 indicates a cover panel for covering a front surface of a light irradiating section being a part of the auxiliary lighting device, while numeral 53 indicates the auxiliary lighting device constituted by a reflector and a Xenon tube, both of which are disposed at a backside space of the cover panel 52 so as to constitute the light irradiating section, and other electronic parts, printed circuit boards, etc. As shown in
Numeral 54 indicates a card-type image recording memory, while numeral 55 indicates a buttery for supplying electric power to each of the sections included in the camera 100. The card-type image recording memory 54 and the buttery 55 are detachable from a cover section (not shown in the drawings).
A release button 56 is disposed on the upper surface of the camera 100. When pushing the release button 56 down to a first step stroke, photographic preparing operations, namely, a focusing operation and a photometry operation, are implemented, and successively, when further pushing the release button 56 down to a second step stroke, an photographic exposing operation is conducted so as to store digital image data of the photographed image into the card-type image recording memory 54. Numeral 57 indicates a main switch for switching the camera 100 between an operating state and a non-operating state. When the camera 100 is switched into the operating state by operating the main switch 57, the operation of each of the main units, etc. is commenced so as to enable the photographic exposing operation, etc. Further, when the camera 100 is switched into the non-operating state by operating the main switch 57, the operation of each of the main units, etc. is deactivated and finalized.
An image display section 58, which is constituted by display elements, such as a LCD (Liquid Crystal Display), an organic EL (Electric Luminescence), etc., so as to display images and other character information, is mounted into the backside space of the camera 100. Further, operating members, such as a zooming button for activating a zooming up or a zooming down operation, a playback button for reproducing the photographed image on the image display section 58, a menu button for displaying various kinds of menus on the image display section 58, a selecting button for selecting a desired function from various functions displayed in a list, etc., are disposed on the camera 100, though those are not shown in the drawings.
The printed circuit boards, through which the abovementioned main units are coupled to each other and on which various kinds of electronic parts are mounted, are disposed in the spaces between the main units, so as to conducts the driving and controlling operations of each of the main units constituting the camera 100, though those are not shown in the drawings. Further, the camera 100 may be provided with an external input/output terminal, a strap binding section, a tripod seating section, etc., though those are not shown in the drawings as well.
Referring to
In the first embodiment, the light irradiating section in which the angles, formed between the two sidewalls constituting the reflector and the surface orthogonal to the light emitting section, are set at values being different from each other.
In
As shown in
Next, a preferable range of the angle α, formed between the sidewall 12 and the surface orthogonal to the light emitting section 10, will be detailed in the following.
In
Concretely speaking, in
(tan−1(a/b)−tan−1((D−a+c)/(r+b−D tan θ)))/2≦α≦(tan−1(a/b)−tan−1((D−a+c)/(r+b+D tan θ)))/2
where α: angle formed between the sidewall 12 located at the position far from the optical axis O and the surface orthogonal to the light emitting section 10,
θ: half angle of view in the long side direction,
D: distance in the optical axis direction of the photographic lens between the photographic position in the most close-up distance photographing mode and the intersect of light bundles in the long side direction,
c: distance in the optical axis direction of the photographic lens between the position of the light emitting section 10 and the intersect of light bundles in the long side direction,
a: distance in the optical axis direction of the photographic lens between the position of the light emitting section 10 and the leading edge of the sidewall 12,
b: distance in the direction orthogonal to the optical axis O of the photographic lens between the center position Q of the light emitting section 10 and the leading edge P of the sidewall 12,
r: distance in the direction orthogonal to the optical axis O of the photographic lens between the optical axis O of the photographic lens and the center position Q of the light emitting section 10.
For instance, when D=60 mm, O=30°, r=40 mm, a=10 mm, b=12 mm and c=10 mm, the range of −2.55°≦α≦17.03° can be found from the above equation. Further, when D=30 mm and other coefficients are the same as those in the above, since the range of −8.20°≦α≦0.53° can be found from the above equation, it is preferable that the sidewall 12 is positioned so that the angle α is established at a value within the above range, corresponding to the layout of the light emitting section in the camera and the specifications of the camera concerned. Incidentally, in the layout shown in
Further, when the photographic lens is a zoom lens, it is preferable that a half angle of view in the long side direction of the wide image is employed as value θ, and it is applicable that the most close-up photographing distance from the first surface of the photographic lens may be substituted for value D.
As mentioned in the foregoing, by setting the angles, formed between the two sidewalls constituting the reflector and the surface orthogonal to the light emitting section, at values being different from each other, and further, by establishing the angle formed between the sidewall located at the position far from the optical axis of the photographic lens and the surface orthogonal to the light emitting section, so that a light, emitted from the center position of the light emitting section and reflected by the leading edge of the sidewall, is irradiated onto such a position that is located within the photographic range in the long side direction in the most close-up distance photographing mode, it becomes possible to provide an auxiliary lighting device, which makes it possible to reduce the unevenness of the exposure amount when conducting the close-up photographing operation, even if the light irradiating section of the auxiliary lighting device is disposed at a position shifted from the optical axis of the photographic lens.
Further, by disposing the sidewall, located at the position far from the optical axis of the photographic lens, at a position in the vicinity of the outside cover of the camera as shown in
As the second embodiment, the light irradiating section of the auxiliary lighting device, which makes it possible to vary the angle formed between one of the two sidewalls constituting the reflector, located at a position at which a distance from the optical axis of the photographic lens is greater than that for the other sidewall, and the surface orthogonal to the light emitting section, will be detailed in the following.
In
In
Further, based on the concept same as that for the first embodiment, with respect to the subject distance (or the photographing distance) and the operation for setting the angle between the sidewall 12 and the surface orthogonal to the light emitting section 10, it is preferable that the angle of the sidewall 12 is changed according to the rotation of the cam plate 16 coupled to the stepping motor 18, which is driven by a controlling section (not shown in the drawings) corresponding to the subject distance, so that a light, emitted from the center position of the light emitting section 10 and reflected by the leading edge of the sidewall 12, is irradiated onto such a position that is located within the photographic range in the long side direction in regard to the subject distance at the time of the photographing operation.
Concretely speaking, it is preferable that the angle of intersection of the sidewall 12 and the surface orthogonal to the light emitting section 10 is changed, so that the angle α, formed between the sidewall 12 and the surface orthogonal to the light emitting section 10, fulfills the following equation.
(tan−1(a/b)−tan−1((D−a+c)/(r+b−D tan θ)))/2≦α≦(tan−1(a/b)−tan−1((D−a+c)/(r+b+D tan θ)))/2
where the definitions for a, b, c, r, θ are the same as those in the equation for the aforementioned first embodiment.
Incidentally, in regard to the method for finding the subject distance D, when the photographic lens has a focusing function, the subject distance D can be found from, for instance, the stop position of the focusing lens, while when the photographic lens has a photometry function, the subject distance D can be found from an output value with respect to the subject distance measured by the photometry device.
Further, in
Concretely speaking, in the second embodiment, the angle α, formed between the sidewall 12 and the surface orthogonal to the light emitting section 10, is changed by rotating the cam plate 16 (shown in
It is applicable that the intersecting angle of the sidewall 12 and the surface orthogonal to the light emitting section 10 is changed either continuously or stepwise corresponding to the subject distance. Further, it is also applicable that the camera is so constituted that the above intersecting angle is changeable only in the close-up image capturing mode.
As mentioned in the foregoing, according to the auxiliary lighting device, which is so constituted that the intersecting angle of one of the two sidewalls constituting the reflector, located at a position at which a distance from the optical axis of the photographic lens is greater than that for the other sidewall, and the surface orthogonal to the light emitting section, is changeable, by changing this intersecting angle corresponding to the subject distance, it becomes possible to provide an auxiliary lighting device, which has such an appropriate light distribution characteristic that makes it possible to reduce the unevenness of the exposure amount caused by the parallax over a range of far to near distance (or Tele to Wide photographing mode), even if the light irradiating section of the auxiliary lighting device incorporated in the camera is disposed at such a position that is shifted from the optical axis of the photographic lens.
Incidentally, although the camera having the photographic lens of the bended optical system is exemplified in the foregoing descriptions, the scope of the present invention is not limited to the above. It is needless to say that the present invention can be applied to such a type of camera that protrudes the photographic lens from its front surface when conducting an image capturing operation. Further, although the camera on which the auxiliary lighting device is disposed at the right side position of the photographic lens is exemplified in the foregoing descriptions, it is also needless to say that the present invention can be applied to such a type of camera on which the auxiliary lighting device is disposed at the left side position of the photographic lens.
Number | Date | Country | Kind |
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2004-334402 | Nov 2004 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP05/19995 | 10/31/2005 | WO | 5/15/2007 |