Optical: systems and elements – Lens – Panoramic
Reexamination Certificate
2003-04-01
2004-07-27
Spector, David N. (Department: 2873)
Optical: systems and elements
Lens
Panoramic
C359S403000
Reexamination Certificate
active
06768598
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image pickup system capable of picking up a wide range such as an omnidirectional or full-circumferential image.
As is generally known, a variety of cameras for simultaneously shooting omnidirectional or full-circumferential images, which comprise a multiplicity of video cameras contained in a casing, have been developed.
As one of the methods for the simultaneous image pickup, for example, a method has been proposed in which the parallax which may be generated among a plurality of cameras is dissolved by ensuring that image pickup view points virtually coincide with each other by use of mirrors arranged in the form of a polygonal pyramid (see U.S. Pat. No. 6,115,176).
A general constitution of one example of the above-mentioned image pickup system using the mirrors arranged in the form of a polygonal pyramid is shown in FIG.
6
. The image pickup system comprises eight plane mirrors
44
arranged in a polygonal pyramid, in this case, an octagonal pyramid, and cameras
41
arranged opposite the plane mirrors
44
in one-to-one correspondence respectively. In
FIG. 6
, two plane mirrors
44
and two cameras
41
disposed on a vertical plane containing the centerline of the image pickup system are shown. Each camera
41
comprises a lens
42
and an image pickup device
43
, and the camera
41
is assembled by attaching the lens
42
to a camera main body (not shown) in which the image pickup device
43
and other component parts are contained.
In the image pickup system, angle-of-view end rays
46
A passing through the uppermost portion of the angle of view, angle-of-view end rays
46
B passing through the lowermost portion of the angle of view, and a ray passing along the optical axis
47
of the lens
42
and reflected by the mirror
44
, are incident on the lens
42
, and are focused to form an image on the image pickup device
43
.
In the plurality of cameras
41
, the virtual view centers
45
generated by the plane mirrors
44
are caused to substantially coincide with each other, whereby parallax can be restrained. As a result, by splicing the images picked up by the plurality of cameras
41
, wide-range images such as an omnidirectional or full-circumferential image can be obtained.
In the case of
FIG. 6
, the angle of incidence of the ray passing along the lens optical axis
47
on the plane mirror
44
is 45 degrees. Therefore, the ray passing along the lens optical axis
47
is horizontally incident on the plane mirror
44
, is reflected by the plane mirror
44
, and is vertically incident on the lens
42
.
In the image pickup system shown in
FIG. 6
, the distance between the angle-of-view end rays
46
A passing through the lowermost portion of the angle of view and a tip corner of the lens
42
is CL. So that the tip of the lens
42
is not mirrored, i.e., to pick up an image free of “eclipse” (shading), it is necessary that CL>0.
As shown in
FIG. 6
, the factors dominantly determining the size of the image pickup system are the height HL from the upper end of the mirror
44
to the lower end of the camera
41
(in
FIG. 6
, to the image pickup device
43
), and the extent LL between the upper end portion of the octagonal pyramid form mirrors
44
. Then, in order to reduce the image pickup system in size, it is required to reduce the height HL and the extent LL.
In order to reduce the height HL and the extent LL, it suffices to set the cameras
41
(the lenses
42
and the image pickup devices
43
) closer to the plane mirrors, as shown in FIG.
7
. As a result, the plane mirrors
44
S can be made to be smaller than the plane mirrors
44
in
FIG. 6
, and the height HS from the upper end of the mirror
44
S to the lower end of the camera
41
and the extent LS of the upper end portion of the octagonal pyramid form mirror
44
S satisfy HS<HL and LS<LL.
In the case of
FIG. 7
, however, the distance between the angle-of-view end rays passing through the lowermost portion of the angle of view and the tip corner of the lens
42
is “negative”, and “eclipse” (shading) occurs, which is inconvenient for image pickup. Therefore, it is necessary that the distance C (best shown in
FIG. 8
) between the angle-of-view end rays passing through the lowermost portion of the angle of view and the tip corner of the lens
42
be positive and as small as possible. In this instance, the diameter D of the tip end of the lens
42
of the camera
41
constitutes a restriction on the reduction of the size of the image pickup system.
From the foregoing, the camera
41
cannot be set closer to the plane mirror than the position where the distance C=0. Besides, in the case where the size (particularly the width) of the camera main body
41
A in which the image pickup device
43
and the like are contained is much larger as compared with the lens
42
, as indicated by broken line in
FIG. 6
, the camera main bodies
41
A of the plurality of cameras
41
will interfere with each other as the cameras
41
are brought closer to the plane mirrors. For example, where each camera is composed by use of three CCD image pickup devices, the camera main body is considerably large.
Due to these restrictions, it has been difficult to achieve a further reduction in the size of the image pickup system. In addition, in the constitution of the image pickup system shown in
FIG. 6
, the plane mirror
44
and the optical axis
47
of the lens
42
of the camera
41
are in the positional relationship of the incidence angle of 45 degrees, and this positional relationship determines the size of the plane mirrors
44
; as a result, the size of the polygonal pyramid form mirror and the overall size of the image pickup system become large.
Particularly, the factors dominantly determining the size of the image pickup device are the height HL from the upper end of the plane mirror
44
to the lower end of the camera
41
and the extent LL of the upper end portion of the pyramid form mirror
44
. Furthermore, the values of the height HL and the extent LL are influenced also by the distance C (CL in
FIG. 6
) between the angle-of-view end rays passing through the lowermost portion of the angle of view and the tip corner of the lens
42
, and, therefore, it is necessary to appropriately set the distance C.
However, the virtual view centers
45
of the plurality of cameras
41
can be caused to substantially coincide with each other, independently from the value of the distance C, so that the distance C can take an arbitrary value. Hitherto, the distance C has not been set to an appropriate value, and, accordingly, the image pickup device has been large in overall size.
SUMMARY OF THE INVENTION
In order to solve the above-mentioned problems, it is an object of the present invention to provide an image pickup system having a smaller size, by reducing the sizes of the mirrors and the image pickup device as a whole.
In accordance with one aspect of the present invention, there is provided an image pickup system comprising a plurality of plane mirrors arranged in the form of a polygonal pyramid, and a plurality of cameras disposed opposite the mirrors respectively, wherein the angle of incidence of the ray passing along the optical axis of a lens of each camera on the plane mirror is less than 45 degrees.
According to the above constitution of the image pickup system according to the present invention, since the angle of incidence of the ray passing along the optical axis of the lens of the camera on the plane mirror is less than 45 degrees, the height from the upper end of the plane mirror to the lower end of the camera can be reduced, and the area of the base surface of the polygonal pyramid constituted of the plane mirrors can be reduced. As a result, it is possible to reduce the overall size of the image pickup system.
In accordance with another aspect of the present invention, there is provided an image pickup system comprising a plurality of plane mirrors arranged in the form of a polygonal pyramid and a plurality of cameras disposed oppo
Bell Boyd & Lloyd LLC
Sony Corporation
Spector David N.
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