WO2001055787A1

WO2001055787A1 - A device and an arrangement method of sector lens for panorama image

Info

Publication number: WO2001055787A1
Application number: PCT/KR2000/000719
Authority: WO
Inventors: Bae-Hun Kim
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-01-27
Filing date: 2000-07-05
Publication date: 2001-08-02
Anticipated expiration: 2002-07-27
Also published as: AU5578500A

Abstract

A sector lens for photographing a limited region of a certain angle and method for arranging sector lenses for panoramic photographing are disclosed. The sector lens and sector lenses arranging method for panoramic photographing are capable of carrying out four-directional panoramic photographing with high resolution. In the sector lens, an eyepiece and an objective lens consisting of a plurality of concave and convex lenses are aligned at their centers, and an image is photographed by a charge-coupled device. The sector lens comprises a focal point formed in front of the objective lens of the lenses; a plurality of boundary plates situated along incidence lines formed through the focal point for holding and protecting the eyepiece and the objective lens; and engaging means formed on the boundary plates and comprised of a plurality of depressions and protrusions so as to allow multiple sector lenses to be engaged with one another.

Description

A DEVICE AND A ARRANGEMENT METHOD OF SECTOR LENS FOR PANORAMA IMAGE

TECHNICAL FIELD

The present invention relates generally to a sector lens for photographing a limited region of a certain angle and sector lenses arranging method for panoramic photographing, and more particularly to a sector lens and sector lenses arranging method for panoramic photographing, which is capable of carrying out four-directional panoramic photographing with high resolution without using a mechanical drive unit.

BACKGROUND ART

A device for photographing and magnifying a subject, in which a plurality of convex and concave lenses are regularly arranged in a straight line, is generally referred to as a lens or zoom lens. A device for exposing a film with the image of a subject formed by light having passed through the lens is generally called a camera. Apparatuses for photographing and processing the image with electric signals by means of a Charge Coupled Device (CCD) include a camcorder, an electronic still camera, a Closed Circuit TV (CCTV) camera, a recording camera for TV stations, and a variety of monitoring cameras.

Each of the image photographing devices and cameras can photograph and monitor the image of a subject situated within the range of the maximum incidence angle of its lens. In order for each of the devices and cameras to monitor the image of a subject situated out of the range of the maximum incident angle of its lens, it should photograph the subject after being rotated at a predetermined angle.

In order to photograph a four-directional panoramic image, there are employed two methods: one method in which an image is continuously photographed while a camera lens is rotated around a focal point or aperture stop, and the other method in which an image formed on a half cylindrical shell- shaped special minor is photographed.

Hereinafter, a conventional panoramic photographing device is described with reference to accompanying drawings.

Figs. 1 to 4 are views showing a prior art. In the drawing, Fig. 1 is a schematic diagram showing the structure of a conventional monitoring camera system. Fig. 2 is a view of an image photographed by a conventional panoramic camera. Fig. 3 is a perspective view showing the structure of another conventional panoramic camera, and Fig. 4 is a view showing an image photographed and processed by another panoramic camera.

Referring to Fig. 1 , the conventional monitoring camera system comprises a camera unit 1 including a zoom lens for enabling long-distance photographing and a CCD for converting the image of a subject into electric signals; a pan and tilt unit 2 integrated with the camera unit 1 to horizontally and vertically rotate the camera unit 1 ; a support 3 for supporting the pan and tilt unit 2 to allow the camera unit 2 to be horizontally and vertically rotated without vibration; an electric cable 4 for transmitting image signals taken by the camera unit 1 and transmitting and receiving control signals from a distance; a monitor unit 5 connected to the electric cable 4 for processing the image signals transmitted from the camera unit 1 and displaying the image to allow a user to see it; and a control unit connected to the electric cable 4 for controlling both the pan and tilt of the pan and tilt unit 2 and the zoom lens of the camera unit 1.

The conventional monitoring camera is described in detail with reference to the above-described drawings. The support 3 is positioned in the vicinity of a subject desired to be photographed or monitored, the pan and tilt unit 2 is attached to the support 3, and the camera unit 1 is fixedly attached to the top of the pan and tilt unit 2. The conventional monitoring camera system is referred to as "a local system", and has not been technologically innovated prominently for a long time. A user positioned in a control or monitor room transmits control signals through the electric cable 4 by the manipulation of the control unit 6 to photograph a subject and magnify a desired portion by rotating the pan and tilt unit 2 and controlling the zoom lens of the camera unit.

The image signals of the subject photographed by the camera unit 1 operated in the above-described manner are transmitted to the monitor unit 5 through the electric cable 4, processed by the image processing function of the monitor unit 5 and displayed on a display by the monitor unit 5, thereby allowing the image of the subject to be recognized and monitored from a remote location. With the rapid development of computer hardware and software technology, high technology, such as Digital Signal Processing (DSP), can be applied to the monitor and control units 5 and 6.

When continuous plane images, that is, a panorama image, are played back using the conventional monitoring camera system, the image captured by the camera unit 1 is recorded or stored on a videotape recorder or computer hardware and is displayed on the monitor unit 5 by rotating the lens of the camera unit 1 around a focal point or an aperture stop and rotating the pan and tilt unit 2 by a certain angle or continuously, as shown in Fig. 2.

For example, as depicted in Fig. 2, first, second and third cuts 7. 8 and 9 photographed one by one in serial order can be displayed as a panoramic image. The above-described panoramic or monitoring camera system cannot monitor the image of the first or third cut 7 or 9 when it monitors the image of the second cut 8, so the image of each cut is a still image.

The conventional monitoring camera system is problematic in that the variations of multiple cuts cannot be monitored at the same time. When the images of multiple cuts are photographed while the camera unit 1 is rotated and timing is controlled, it is difficult to connect the connected portions of the images of the cuts to one another because the precision of the mechanically operated pan and tilt unit 2 is deteriorated by continual use. Additionally, the life span of the mechanically operated pan and tilt unit 2 is limited, so the images of the required portions cannot be photographed and the maintenance of the system is relatively difficult when twenty four-hour continuous photographing is necessary and a mechanical failure occurs.

As illustrated in Fig. 3, an improved panoramic camera system, which has solved some of the above-described problems, comprises a fixed special mirror 1 1 having a circular cross-section, and a camera unit 1 fixed at a position under the special mirror 1 1 and comprised of a lens and a Charge Coupled

Device (CCD).

In the above-described improved panoramic camera system, the image of a four-directional subject formed on the special mirror 1 1 is monitored and photographed by the camera unit 1 as a first frame 12 shown in Fig. 4 and inputted as image signals, and a panoramic image is displayed as a second frame 13 by the monitor unit 5 using a digital signal processing technique.

The conventional improved panoramic camera system is advantageous in that a four-directional image is photographed in real time at the same time, but problematic in that resolution cannot be sufficiently improved while a particular portion, desired to be intensively monitored, is magnified. Accordingly, the conventional improved panoramic camera system has shortcomings that the quality of an image is low for industrial purposes such as monitoring purposes, and a distortion phenomenon such as the distortion of an image is difficult to completely eliminate.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a sector lens and sector lenses arranging method for panoramic photographing, which is capable of photographing a four-directional panoramic image in real time at the same time without a pan and tilt unit and, thus, without the movement of its camera, improving its resolution by the employment of multiple lenses, and photographing the image of a subject without distortion.

Another object of the present invention is to provide a sector lens and sector lenses arranging method for panoramic photographing, in which as occasions demand, lenses are combined in various manners, thereby allowing an indoor or outdoor subject to be intensively monitored with high resolution.

In order to accomplish the above object, the present invention provides a sector lens for panoramic photographing, in which an eyepiece and an objective lens consisting of a plurality of concave and convex lenses are aligned at their centers, and an image is photographed by a charge coupled device, comprises: a focal point formed in front of the objective lens of the lenses; a plurality of boundary plates situated along incidence lines formed through the focal point for holding and protecting the eyepiece and the objective lens; and engaging means formed on the boundary plates and comprised of a plurality of depressions and protrusions so as to allow multiple sector lenses to be engaged with one another.

In addition, a sector lenses arranging method for panoramic photographing, comprises: dividing 180 degrees by a vertical or horizontal incidence angle formed though the focal point of a sector lens, and continuously attaching the corresponding number of sector lenses to one another on the same vertical or horizontal plane.

In addition, a sector lenses arranging method for panoramic photographing, comprises: a first step of providing sector lenses the number of which is identical with a quotient obtained by dividing 360 degrees by a horizontal incidence angle formed through the focal point of a sector lens; a second step of forming a first group of sector lenses by alternately arranging sector lenses in the plurality of sectors formed in the first step; a third step of forming a second group of sector lenses in parallel with the first group of sector lenses by arranging sector lenses in the remaining sectors; and a fourth step of spacing the first group of sector lenses and the second group of sector lenses so that the arrangement line of the vertical incidence angle of the first group of sector lenses does not overlap with the lower portions of the second group of sector lenses, or the arrangement line of the vertical incidence angle of the second group of sector lenses does not overlap with the upper portions of the first groups of sector lenses. BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a schematic diagram showing the structure of a conventional monitoring camera system;

Fig. 2 is a view of an image photographed by a conventional panoramic camera;

Fig. 3 is a perspective view showing the structure of another conventional panoramic camera;

Fig. 4 is a view showing an image photographed and processed by another conventional panoramic camera;

Fig. 5 is a diagram showing the basic principle of a sector lens applied to the present invention; Fig. 6 is a schematic diagram showing the structure of a sector lens in accordance with one embodiment of the present invention;

Fig. 7 is a perspective view showing the sector lens of the embodiment of the present invention;

Fig. 8 is a view showing the arrangement of sector lenses on a vertical or horizontal plane for panoramic photographing;

Fig. 9 is a view showing the improvement of resolution by sectional photographing;

Fig. 10 is a view showing the arrangement of a first group of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention;

Fig. 1 1 is a view showing the arrangement of a second group of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention; Fig. 12 is a sectional view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention;

Fig. 13 is a perspective view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention;

Fig. 14 is a sectional view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with another embodiment of the present invention;

Fig. 15 is a perspective view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with another embodiment of the present invention;

Fig. 16 is a view showing the use of sector lenses arranged in accordance with an embodiment of the present invention; and

Fig. 17 is a flowchart showing a sector lenses arranging method in accordance with an embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a sector lens and sector lenses arranging method for panoramic photographing in accordance with the present invention is described with reference to accompanying drawings. Among the accompanying drawings, Fig. 5 is a diagram showing the basic principle of a sector lens applied to the present invention, Fig. 6 is a schematic diagram showing the structure of a sector lens in accordance with one embodiment of the present invention, Fig. 7 is a perspective view showing the sector lens of the embodiment of the present invention, Fig. 8 is a view showing the arrangement of sector lenses on a vertical or horizontal plane for panoramic photographing, Fig. 9 is a view showing the improvement of resolution by sectional photographing, Fig. 10 is a view showing the arrangement of a first group of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention, Fig. 1 1 is a view showing the arrangement of a second group of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention, Fig. 12 is a sectional view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention. Fig. 13 is a perspective view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with an embodiment of the present invention, Fig. 14 is a sectional view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with another embodiment of the present invention, Fig. 15 is a perspective view showing the arrangement of first and second groups of sector lenses for four-directional panoramic photographing in accordance with another embodiment of the present invention, Fig. 16 is a view showing the use of sector lenses arranged in accordance with an embodiment of the present invention, and Fig. 17 is a flowchart showing a sector lenses arranging method in accordance with an embodiment of the present invention. With reference to accompanying drawings, a sector lens 50 for panoramic photographing, in which an eyepiece 88 and an objective lens 89 consisting of a plurality of concave and convex lenses are aligned at their centers, and an image is photographed by a charge coupled device 60, comprises: a focal point 20 formed in front of an objective lens of the lenses; a plurality of boundary plates 82 and 84 situated along incidence lines 23 formed through the focal point 20 for holding and protecting the eyepiece 88 and the objective lens 89; and engaging means formed on the boundary plates 82 and 84 and comprised of a plurality of depressions 86 and protrusions 87 so as to allow multiple sector lenses to be engaged with one another.

The objective lens 89 is provided along its peripheral edge with an engaging groove 52 to be situated outside of lines formed by refraction of the outermost incidence lines 23; and wherein the objective lens 89 is secured to the boundary plates 82 and 84 by means of the groove 52.

A sector lenses arranging method for panoramic photographing, comprises: dividing 180 degrees by a horizontal incidence angle 26 formed through the focal point 20 of a sector lens 50, and continuously attaching the corresponding number of sector lenses 50 to one another on the same horizontal plane, or dividing 180 degrees by a vertical incidence angle 27 formed through the focal point 20 of a sector lens 50, and continuously attaching the corresponding number of sector lenses 50 to one another on the same vertical plane.

The present invention provides a sector lenses arranging method for panoramic photographing, comprises: a first step S10 of providing sector lenses 50 the number of which is identical with a quotient obtained by dividing 360 degrees by a horizontal incidence angle formed through the focal point 20 of a sector lens 50; a second step S20 of forming a first group of sector lenses 80 by alternately arranging sector lenses 50 in the plurality of sectors 26 formed in the first step S 10; a third step S30 of forming a second group of sector lenses 90 in parallel with the first group of sector lenses 80 by arranging sector lenses 50 in the remaining sectors 26; and a fourth step S40 of spacing the first group of sector lenses 80 and the second group of sector lenses 90 so that the arrangement line of the vertical incidence angle 27 of the first group of sector lenses 80 does not overlap with the lower portions of the second group of sector lenses 90, or the arrangement line of the vertical incidence angle 27 of the second group of sector lenses 90 does not overlap with the upper portions of the first groups of sector lenses 80.

Hereinafter, one embodiment of the present invention is described in detail with reference to accompanying drawings.

In relation to the principle of a sector lens, a hexahedron-shaped frame 30 is provided, a pinhole is formed on one side surface of the frame to form a focal point or aperture stop, and a screen 45 is situated on the opposite side.

When the focal point 20 of the frame 30 is directed toward a subject or an actual object 10. the inverted image 40 is formed on the screen 45.

Such a structure is a so-called pinhole camera. The sector lens 50, which is applied to the present invention, is described in detail with reference to Figs. 6 and 7. The sector lens 50 includes first boundary plates 82 on its upper and lower sides and second boundary plates 84 on its left and right sides, which form planes and are situated to pass through incidence lines 23 having an incidence angle α, or 25. thus forming the sector lens 50 in the shape of a truncated pyramid. A square-shaped object lens 89 is situated on the top surface of the truncated pyramid.

A groove 52 is formed along the peripheral edge of the object lens 89 to be situated outside of the lines formed by the refraction of the outermost incidence lines 23. The object lens 89 is fixedly engaged with the upper, lower, left and right boundary plates 82 and 84 by means of the groove 52. The object lens 89 and an eyepiece 88. comprised of a plurality of convex and concave lenses, are aligned to allow their centers to be situated in a straight line passing through the focal point 20. As a result, chromatism caused by the lenses is eliminated, the image 40 of a subject is formed on the charge coupled device 60, and a distance to the charge coupled device on which the image 40 is formed is adjustable.

The image 40 formed by the sector lens 50 is converted into electric signals and inputted by the charge coupled device 60.

In the sector lens 50. the position of the object lens 89 and the size of the incidence angle 25 are appropriately determined by a designer. A plurality of sector lenses 50 can be rapidly, precisely and easily assembled together side by side without a bonding agent or screws, since the incidence angles 25 of the sector lens 50 are fixed, for example, at 36 degrees. one or more engaging depressions 86 are formed on the first boundary plates 82. one or more engaging protrusions 87 engaged with the engaging depressions 86 are formed on the second boundary plates 84. and the engaging depressions and protrusions 86 and 87 are formed in the shape of a dovetail or "T" letter. By way of example, referring to Fig. 8, when three sector lenses 50 are attached to one another by means of the engaging depressions and protrusions 86 and 87 on the same vertical plane to have the same focal point, there can be photographed and monitored a subject that exists within a range of 108 degrees in a vertical direction and 36 degrees in a horizontal direction.

On the other hand, when three sector lenses 50 are continuously attached to one another on the same horizontal plane, there can be photographed and monitored a subject that exists within a range of 108 degrees in a horizontal direction and 36 degrees in a vertical direction. One to five sector lenses can be continuously arranged as occasions demand, so there can be photographed and monitored a subject that exists within a range of 36 to 180 degrees in vertical and horizontal directions without a distortion phenomenon. Electric signals, outputted from the charge coupled devices 60 of the continuously arranged sector lenses 50, are received and processed using a digital signal processing technique, and, thus, displayed with high resolution.

A method for improving resolution made by a plurality of sector lenses 50 is described in detail with reference to Fig. 9.

By way of example, the resolution of the image 40 monitored by a single sector lens 50 is 760:490 pixels. The left view of Fig. 9 shows an image formed by photographing a subject with a single sector lens 50. and the resolution of the image is a total of 372.400 pixels. The central view of Fig. 9 shows an image formed by photographing the same subject as that of the left view by sectors with four sector lenses continuously arranged in horizontal and vertical directions. A single image 40 is monitored in a total of 1 ,489,600 pixels, and the resolution is increased by four times. The right view of Fig. 9 shows an image formed by photographing the same subject as that of the left view with nine sector lenses continuously arranged in horizontal and vertical directions.

The resolution of a total of 3, 351, 600 pixels increased by nine times can be obtained, so a particular portion can be intensively magnified and monitored. In more detail, the signals of the image 40 photographed as described above are can be processed by a digital signal processing technique.

Accordingly, while the entire region is monitored, a particular portion desired to be intensively monitored is can be magnified, thereby allowing the sector lens

50 to be utilized for industrial or manufacturing purposes. The sector lens for four-directional photographing and monitoring is described with reference to Figs. 10 to 17 as a different embodiment of the present invention.

The sector lens 50 has an incidence angle of 36 degree each in the vertical and horizontal directions. Accordingly, when horizontal 360 degrees are divided by 36 degrees, ten sectors are formed.

The ten photographing sectors, as shown in Figs. 10 and 1 1 , are designated by "A" to "J", and ten, corresponding to the number of the divided sectors, sector lenses 50 are provided (S10).

In a second step, the sector lenses 50, as shown in Fig. 10, are disposed in the "B", "D", "F", "H^" and "J" sectors of "A" to "J" sectors, respectively, to allow their focal points to coincide with one another on the same plane, thereby forming a first group of sector lenses (80; S20).

Referring to Fig. 9, a plurality of sector lenses 50 are disposed on the same plane in the "A". "C", "E", "G" and "I^" sectors, in which the sector lenses 50 have not been disposed in the second step S20. to allow their focal points to coincide with one another. Additionally, these sector lenses 50 are arranged on a plane, parallel with the plane on which the first group of sector lenses 80 are arranged, to allow their focal point to lie on the same straight line on which the focal point of the first group of sector lenses 80 lie. As a result, a second group of sector lenses 50 are formed (S30). Referring to Fig. 12, there is illustrated in cross-section a state in which the first and second groups of sector lenses 50 are arranged in accordance with the above-described steps. In the drawing, the second group of sector lenses 90 are arranged for their lower portions not to invade the boundary lines of the vertical incidence angle 27 formed by the first group of sector lenses 80, or the first group of sector lenses 90 are arranged for their upper portions not to invade the boundary lines of the vertical incidence angle 27 formed by the second group of sector lenses 90 (S40).

A plurality of the sector lenses 50 arranged in accordance with the present invention photograph or monitor a four-directional region in a horizontal direction and the region of 36 degrees in a vertical direction using the first and second groups of sector lenses 80 and 90.

The three-dimensional construction of the first and second groups of sector lenses 80 and 90 is illustrated in Fig. 13.

The above-described sector lenses arranging method for panoramic photographing is to photograph or monitor the range of 360 degrees in a horizontal direction and 36 degrees in a vertical direction. A sector lenses arranging method for photographing or monitoring the range of 360 degrees in a horizontal direction and 72 degrees in a vertical direction in accordance with a different embodiment is shown in Fig. 14. With reference to Fig. 14, a plurality of sector lenses 50 are attached to the upper surfaces of the sector lenses 50 constituting the first group of sector lenses 50 so as to allow their focal points to coincide with one another, thereby forming a first additional group of sector lenses 85. At the same time, a plurality of sector lenses 50 are attached to the upper surfaces of the sector lenses 50 constituting the second group of sector lenses 50 so as to allow their focal points to coincide with one another, thereby forming a second additional group of sector lenses 95.

The uppermost arrangement line 83 formed by the uppermost vertical incidence angle 27 of the first groups of sector lenses 80 and 85 does not overlap with the lower portions of the lowermost sector lenses 90 of the second groups of sector lenses 90 and 95, or the lowermost arrangement line 93 formed by the lowermost vertical incidence angle 27 of the second groups of sector lenses 90 and 95 does not overlap with the upper portions of the uppermost sector lenses 85 of the first groups of sector lenses 80 and 85. Additionally, two focal points of the first and second groups of sector lenses lie on a single vertical line. Additionally, the first groups of sector lenses 80 and 85 are situated near to the second groups of sector lenses 90 and 95.

Fig. 15 is a three-dimensional view showing the first and second groups of sector lenses 80, 85, 90 and 95.

In more detail, sector lenses are additionally attached to the sector lenses 50 of the first and second groups 80. 85, 90 and 95. so the photographed or monitored vertical region or angle can be extended.

Fig. 16 is a view showing a completed sector lens in accordance with the present invention.

INDUSTRIAL APPLICABILITY A sector lenses arranging method for panoramic photographing has an effect in which a four-directional subject is panoramically photographed and monitored in real time.

Additionally, a particular portion of a photographed subject can be magnified in high resolution by a digital signal processing technique, so the particular portion can be monitored for industrial and manufacturing effects.

Additionally, an expensive mechanical drive unit and a corresponding control unit are not utilized, so the costs of the apparatus is low, the costs of maintenance is low. and a four-directional subject can be easily panoramically photographed or monitored.

Claims

1. A sector lens for panoramic photographing, in which an eyepiece and an objective lens consisting of a plurality of concave and convex lenses are aligned at their centers, and an image is photographed by a charge coupled device, comprising: a focal point formed in front of said objective lens of said lenses; a plurality of boundary plates situated along incidence lines formed in accordance with said focal point for holding and protecting said eyepiece and said objective lens; and engaging means formed on said boundary plates and comprised of a plurality of depressions and protrusions so as to allow multiple sector lenses to be engaged with one another.

2. The sector lens according to claim 1 , wherein said objective lens is provided along its peripheral edge with an engaging groove to be situated outside of lines formed by refraction of the outermost incidence lines; and wherein said objective lens is secured to said boundary plates by means of said groove.

3. A sector lenses arranging method for panoramic photographing, comprising: dividing 180 degrees by a vertical or horizontal incidence angle formed through a focal point of a sector lens, and continuously attaching the corresponding number of sector lenses to one another on the same vertical or horizontal plane.

4. A sector lenses arranging method for panoramic photographing, comprising: a first step of providing sector lenses the number of which is identical with a quotient obtained by dividing 360 degrees by a horizontal incidence angle formed through a focal point of a sector lens; a second step of forming a first group of sector lenses by alternately arranging sector lenses in the plurality of sectors formed in said first step; a third step of forming a second group of sector lenses in parallel with said first group of sector lenses by arranging sector lenses in the remaining sectors; and a fourth step of spacing said first group of sector lenses and said second group of sector lenses so that an arrangement line of a vertical incidence angle of said first group of sector lenses does not overlap with lower portions of said second group of sector lenses, or an arrangement line of a vertical incidence angle of said second group of sector lenses does not overlap with upper portions of said first groups of sector lenses.

5. The sector lenses arranging method according to claim 3 or 4, wherein said focal points of said sector lenses are positioned at a point on a single plane.

6. The sector lenses ananging method according to claim 4, wherein said first group of sector lenses are each provided with one or more sector lenses to be continuously arranged in a vertical direction and to allow their focal points to coincide with one another; and wherein said second group of sector lenses are each provided with one or more sector lenses to be continuously arranged in a vertical direction and to allow their focal points to coincide with one another.

7. The sector lenses arranging method according to claim 6, wherein said first groups of sector lenses are situated near to said second groups of sector lenses so that an uppermost arrangement line of said first groups of sector lenses does not overlap with lower portions of lowermost sector lenses of said second groups of sector lenses, or a lowermost arrangement line of said second groups of sector lenses does not overlap with upper portions of uppermost sector lenses of said first groups of sector lenses.

8. The sector lenses arranging method according to 4. 6 or 7. wherein said first and second groups of sector lenses are arranged to allow two focal points of said first and second groups of sector lenses to lie on a single vertical line.