Abstract:
An omnidirectional camera device is able to restrict a range in which images of objects are picked up. This omnidirectional camera device comprises a rotationally-symmetric convex mirror ( 24 ) fixedly attached to one end of a transparent tube assembly ( 20 ), an image pickup means ( 32 ) disposed on the other end of the tube assembly in an opposing relation to this convex mirror and a cover assembly ( 60 ) disposed on the tube assembly for restricting the range in which light becomes incident on the convex mirror. The cover assembly is mounted on one end side of the tube assembly. The cover assembly is a shielding cover assembly and includes a cover member ( 60 B). The cover assembly is attached to the tube assembly so as to become freely rotatable. The direction and the range in which images of objects should be picked up may be adjusted by the attachment position of the cover assembly and a shielding angle α of the cover assembly. Thus, since undesired video information may be eliminated, only pictures of objects in the desired ranges may be picked up, which becomes effective in analyzing information.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an omnidirectional camera device for use with a surveillance camera or the like. More particularly, this invention relates to an omnidirectional camera device which is able to pickup not only images of objects in all directions but also only an image of an object in a specified range, thereby hindering the camera device from picking up useless images of extra objects. 
     2. Description of the Related Art 
     Heretofore, there is known an omnidirectional camera device capable of picking up images of objects existing in all directions. 
     FIG. 1 of the accompanying drawings shows such an omnidirectional camera device  10  capable of picking up images of objects in all directions. As shown in FIG. 1, this camera device  10  uses a rotationally-symmetric convex mirror  12 , and is able to pick up images of objects in all directions (360°) incident on the convex mirror  12  by an image pickup means, e.g. a video camera  14 . 
     If such omnidirectional camera device which is able to pick up images of objects in all directions is installed at a specified position in the room, we can almost catch all situations within the room as if we were at the actual room. Therefore, since a large number of image pickup means need not be installed at different positions within the same room, this camera device is very suitable for watching the inside of the room and the like. 
     The direction of objects to be picked up should be restricted, otherwise light incident on the convex mirror  12  will not be introduced into the video camera  14  efficiently. Moreover, when the omnidirectonal camera device  10  is installed near the window in the proximity of the ceiling as shown in FIG. 2, only images of objects in the front directions shown at least by an angular extent  74   are necessary video information, but images of objects in the directions shown by an angular extent −θ are useless video information for a user. On the contrary, it is frequently observed that such useless video information might disturb the user. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an omnidirectonal camera device in which the aforementioned defects encountered with the prior art can be obviated. 
     It is another object of the present invention to provide an omnidirectional camera device capable of choosing necessary information and useless information by restricting a range in which light becomes incident on a convex mirror. 
     According to an aspect of the present invention, there is provided an omnidirectional camera device which is comprised of a rotationally-symmetric convex mirror fixedly attached to one end of a transparent tube assembly, an image pickup device disposed on the other end of the tube assembly in an opposing relation to the convex mirror and a cover assembly being disposed on the tube assembly so as to restrict an extent in which light becomes incident on the convex mirror. 
     According to the present invention, a shielding cover assembly is rotationally attached to the outside of the tube assembly, whereby an angular extent in which light becomes incident on the convex mirror can be restricted. The extent in which incident light should be shielded and the direction of incident light that should be shielded may be determined by adjusting the attachment position of the cover assembly. 
     Further, since incident light is shielded by the cover assembly, all undesired information may be eliminated. Hence, the omnidirectional camera system is able to reliably pick up images of objects existing in the necessary directions and necessary ranges. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a conceptual diagram of an omnidirectional camera device according to the related art; 
     FIG. 2 is a diagram used to explain the necessity of restricting the directions in which images of objects are picked up; 
     FIG. 3 is a cross-sectional view showing a main potion of an omnidirectional camera device according to an embodiment of the present invention; 
     FIG. 4 is a perspective view showing a convex mirror used in the omnidirectional camera device according to the embodiment of the present invention; 
     FIG. 5 is a perspective view showing an example of a cover assembly of the omnidirectional camera device according to the present invention; 
     FIG. 6 is a diagram showing an angle at which a cover member is opened; 
     FIG. 7 is a perspective view showing other example of a cover assembly of the omnidirectional camera device according to the embodiment of the present invention; 
     FIG. 8 is a cross-sectional view of FIG. 7; 
     FIG. 9 is a diagram showing an angle at which the cover assembly of other example is opened; 
     FIG. 10 is a cross-sectional view taken along the line I—I in FIG. 9; 
     FIG. 11 is a cross-sectional view similar to FIG. 3, and illustrates a convex mirror according to other embodiment of the present invention; 
     FIG. 12 is a cross-sectional view similar to FIG. 3, and illustrates a convex mirror according to a further embodiment of the present invention; 
     FIG. 13 is a perspective view showing a cover assembly according to a further embodiment of the present invention; and 
     FIG. 14 is a cross-sectional view showing a cover assembly according to yet a further embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An omnidirectional camera device according to the embodiments of the present invention will be described below in detail with reference to the drawings. 
     FIG. 3 is a cross-sectional view showing a main portion of an omnidirectional camera device  10  according to an embodiment of the present invention. As shown in FIG. 3, the omnidirectional camera device  10  comprises a transparent tube assembly  20  whose respective ends are opened, a convex mirror  24  fixedly attached to one end, e.g. an upper end of the transparent tube assembly  20  and an image pickup means, e.g. a very small video camera  32  fixedly fitted into a lower end side which is the other end of the transparent tube assembly  20 . 
     The tube assembly  20  is made of a transparent material and produced by glass or transparent plastics. Since the dimensions of the tube assembly  20  are determined in accordance with a use of the omnidirectional camera device  10 , when the omnidirectional camera device  10  is applied to a surveillance camera and the like, the tube assembly  20  has an outer diameter ranging from approximately one centimeter to several centimeters and a length of several centimeters. The outer and inner peripheral surfaces of the tube assembly  20  are produced by mirror finishing more than a certain extent. 
     The convex mirror  24  fixedly attached to the upper end of the tube assembly  20  comprises a disk-like base  24 A and a hemispherical convex portion  24 B formed as one body with this base  24 A as shown in FIG.  4 . As shown in FIG. 4, the convex mirror  24  is generally attached to the omnidirectional camera device  10  in such a manner that its convex portion  24 B is directed downward. The convex mirror  24  is produced by molding of a suitable material such as brass. The convex portion  24 B is produced by mirror finishing. 
     As shown in FIG. 3, a center needle  23  is fixedly fitted into the convex mirror  24  at its top along the optical axis of the concave portion  24 B in such a manner that it may be projected to the outside from the mirror-finished surface of the concave portion  24 B by a predetermined length. The center needle  23  having predetermined length and thickness is such one that is used to hinder undesired reflected light from being introduced into the side of the video camera  32 . 
     As shown in FIG. 3, the base  24 A has an outer diameter which is substantially the same as that of the tube assembly  20 . The convex portion  24 B has an outer diameter which is substantially the same as an inner diameter of the tube assembly  20  in such a manner that it may be fixedly fitted into the inner surface of the tube assembly  20 . The convex portion  24 B has a concave groove  25  formed at a boundary between it and the base  24 A. This concave groove  25  is used to prevent an adhesive from being leaked into the mirror-finished surface side when the convex mirror  24  is bonded to the upper end surface of the tube assembly  20  by a suitable means such as an adhesive. 
     An annular flange  26  which is fitted into the above-mentioned concave groove  25  is formed as one body with the inner surface of the tip end of the tube assembly  20 . The convex mirror  24  is fixedly inserted into the inside of the tube assembly  20  from the upper end as in the illustrated state. The convex mirror  24  may be fixed to the upper end of the tube assembly  20  by a suitable means such as an adhesive if necessary A cap  28  is fixedly mounted on the side of the base  24 A of the convex mirror  24 . If necessary, the cap  28  maybe strongly fixed to the convex mirror  24  and the tube assembly  20  by a suitable means such as an adhesive. 
     The video camera  32  is fixedly mounted on the lower end side of the tube assembly  20  through an optical system  30 . The optical system  30  comprises a cylindrical lens-barrel  34  and one or a plurality of optical lenses  36  secured within the lens-barrel  34 . A thread groove  38  is formed on the inner surface of the lower end of the tube assembly  20 . The thread groove  38  is meshed with a thread groove  40  formed around the outer peripheral portion of the tip end of a housing  50  through a rubber ring  37  mounted on the inside of the tube assembly  20 , thereby resulting in the optical system  30  being formed as one body with the housing  50 . By changing the depth in which the optical system  30  is meshed with the housing  50 , it is possible to adjust an optical distance between the optical system  30  and an image pickup element, e.g. a two-dimensional sensor (CCD (charge-coupled device) sensor)  42  fixed to the inside of the housing  50 . 
     The housing  50  is secured to the tube assembly  20  by a connection ring  44 . The connection ring  44  is a cylindrical member having an annular flange  48  formed on the lower end thereof. The connection ring  44  has a screw thread  46  formed around the inner periphery of the tip end thereof. The flange  48  also has a screw thread  49  formed in the inside portion thereof. Then, the screw thread  46  of the connection ring  44  is engaged into the lower end of the tube assembly  20 , and the housing  50  is engaged into the connection ring  44 . Thus, the housing  50  of the video camera  32  can be fixedly attached to the tube assembly  20  through the connection ring  44 . 
     The video camera  32  is attached to the tube assembly  20  in such a manner that the optical axis of the video camera  32  may agree with that of the convex mirror  24 . With this arrangement, the tube assembly  20 , the convex mirror  24  and the video camera  32  may be formed as one body under the condition that an optical axis Lb of the convex mirror  24  and an optical axis Lc of the video camera  32  are arrayed on substantially the same line. 
     With this arrangement, since images of objects in the angular extent of 360 degrees about the tube assembly  20  may be displayed on the convex mirrors  24 , if such images of objects are focused on the two-dimensional sensor  42  of the video camera  32 , then the video camera  32  is able to pick up images of objects in all directions of 360 degrees. 
     According to the present invention, in addition to the above-mentioned arrangement, a cover assembly  60  for restricting the range in which an image of an object is picked up is detachably attached to this tube assembly  20 . The cover assembly  60  is the shielding assembly for shielding the introduction of external light from a part of the outer peripheral surface of the tube assembly  20 . The cover assembly  60  comprises a mount head (attachment head)  60 A to be attached to the tube assembly  20  and a cover member (fan-like fin)  60 B unitarily communicated with the mount head  60 A. 
     The cover member  60 B forms apart of the tube assembly, and is formed in a predetermined angular extent α as shown in FIG.  6 . The angular extent α in which incident light should be shielded is set in accordance with a use of the camera device. The cover member  60 B may be made long enough to cover the cover assembly  60  approximately up to the position at which the rubber ring  37  is attached. In response to the shielding angle α of the cover member  60 B, as shown in FIG. 5, the mount head  60 A also is recessed by an angle (360°−α) where α&gt;180°. 
     As shown in FIG. 3, the mount head  60 A is mounted on the cover assembly  60  so as to close the cap  28  attached to the upper end of the tube assembly  20 . At that very time, in order to protect the cover assembly  60  from being disengaged from the tube assembly  20 , the cover member  60 B includes an engagement step portion  64  formed on the inner surface thereof at its portion in which the engagement step portion  64  may contact with the end of the flange  28   a  of the cap  28 . 
     When the cover assembly  60  is attached to the tube assembly  20 , the cover assembly  60  is attached to the tube assembly  20  under the condition that the cover member  60 B thereof is nearly closely contacted with the outer peripheral surface of the tube assembly  20  with the result that external light from the side of the cover member  60 B may be prevented from entering the inside of the tube assembly  20 . That is, external light existing in the angular extent a may be shielded completely. 
     In the case of the cover assembly  60  in which the shielded angular extent α exceeds 180 degrees as shown in FIG. 6, the cover assembly  60  may be nearly reliably attached to the tube assembly  20  by the engagement step portion  64  formed on the side of the mount head  60 A. Also, since the band-like engagement step portion  64  formed on the inner surface of the cover member  60 B functions as a rotation step portion for rotating the cover assembly  60  relative to the tube assembly  20 , the opening direction relative to the tube assembly  20 , i.e. the shielding region may be adjusted by rotating the cover assembly  60 . As the cover assembly  60 , it is possible to use such a cover assembly which is produced by molding a suitable material such as plastics. 
     Although there still remains a risk that light incident on the inner surface of the cover member  60 B will be reflected on the cover assembly  60  and again introduced into the convex mirror  24 , light that was again introduced into the convex mirror  24  may be interrupted by the center needle  23  and thereby can be prevented from becoming incident on the video camera  32 . By way of precaution, the inner surface of the cover member  60 B may be coated with an optical absorption film. 
     Although the mount head  60 A shown in FIG. 5 is recessed in response to the shielding angle α, such recessed portion is not always required but instead the mount head  60 A maybe modified as amount head  60 A by which the cap  28  is completely closed as shown in FIG.  7 . In this case, as shown in FIG. 8, a circumferential engagement step portion  64  is formed on the inner surface of the cover assembly  60 B and the mount head  60 A. By this circumferential engagement step portion  64 , the cover assembly  60  may be fixed to the tube assembly  20  more reliably. 
     When the shielding angle α of the cover member  60 B is less than 180 degrees as shown in FIG. 9, in order that the mount head  60 A may completely cover the cap  28  similarly to FIG. 7, the mount head  60 A may be shaped in such a way as to completely close the cap  28  as shown in FIG.  10 . 
     FIGS. 11 and 12 are cross-sectional views showing modified examples of the convex mirror  24  shown in FIGS.  3  and  4 . While the example shown in FIGS. 3 and 4 uses a part of a hemisphere as the convex portion  24 B, the modified example shown in FIG. 11 uses an approximately truncate circular cone surface as a convex portion  24 C, and the modified example shown in FIG. 12 uses a circular cone surface forming approximately a surface of parabolic type as a convex portion  24 D. In either case, it is possible to obtain image information of a predetermined angular extent by image processing. 
     FIG. 13 shows a further modified example of FIG.  5 . While the annular engagement step portion is formed by making the thickness of the cover member  60 B communicating with the step portion  64  the same in FIG. 5, according to the further modified example of FIG. 13, the step portion  64  might be replaced with an annular protrusion  70  formed on the inside of the cover member  60 B. According to this annular protrusion  70 , the thickness of the cover member  60 B can be reduced. Further, since the annular protrusion  70  prevents the inner surface of the cover member  60 B from contacting with the outer peripheral surface of the tube assembly  20 , there are then the advantages that the rotation of the cover assembly  60  can be adjusted easier and that the outer peripheral surface of the tube assembly  20  can be made difficult to damage. 
     FIG. 14 shows a still further modified example of FIG.  11 . Also in this case, the step portion  64  is replaced with the annular protrusion  70  formed on the inside of the cover member  60 B. With this arrangement, there can be achieved the effects that the thickness of the cover member  60 B maybe reduced without degrading the engagement effect. 
     As set forth above, according to the present invention, the omnidirectional camera device includes the cover assembly which can shield undesired incident light. 
     According to the present invention, since incident light is shielded by the cover assembly, undesired information can be completely eliminated, and images of objects existing only in the necessary directions and in the necessary angular extent can be picked up reliably. Since the extent in which incident light should be shielded and the direction of incident light that should be shielded may be determined by adjusting the attachment position of the cover assembly, the shielding range can be set in accordance with the use of the camera device. Furthermore, since the direction in which incident light should be shielded may be adjusted extremely easily, the omnidirectional camera device according to the present invention can cope with the change of the use of the camera device freely. 
     Therefore, the omnidirectional camera device according to the present invention is extremely suitable as a surveillance camera installed within the shop or the room and also suitable as a camera device for effecting a demonstration in an exhibition hall. 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments and that various changes and modifications could be effected therein by one skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims.