360 degree viewing angle lens unit and optical lens system using same

1. Technical Field

The present disclosure relates to lens systems and, particularly, to a 360° viewing angle lens unit capable of imaging a lateral perspective of 360° circumference along the optical axis thereof, and an optical lens system utilizing the 360° viewing angle lens.

2. Description of Related Art

360° viewing angle lens systems are commonly used in a camera system for capturing images in full-360° angle-of-view. In a general 360° viewing angle lens systems, a 360° viewing angle lens is often arranged in front of a regular lens group along the optical axis of the regular lens group. As such, the regular lens group can collect the lights in front of the 360° viewing angle lens, while the 360° viewing angle lens can collect the image lights around the optical axis in a 360° circumference. However, in such an arrangement, the 360° viewing angle lens system may only capture an image including a front perspective along the optical axis of the regular lens group and another circumference perspective surrounding the optical axis of the regular lens group at the same time at most. It limits some special requirements for capturing images along different directions.

Therefore, it is desirable to provide a 360° viewing angle lens unit and an optical lens system using the 360° viewing angle lens, which can overcome the above-mentioned problems.

Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments.

The FIGURE is a schematic view of an exemplary embodiment of an optical lens system using a 360° viewing angle lens unit.

Embodiments of the present disclosure will now be described in detail below, with reference to the accompanying drawing.

Referring to the FIGURE, an optical lens system 100 , according to an exemplary embodiment, is shown. In this embodiment, the optical lens system 100 is adapted to a digital camera. In other embodiments, the optical lens system 100 may be employed in a video camera, a projector, or a cell phone. The optical lens system 100 includes, from the object side to the image side, a 360° viewing angle lens unit 110 and a regular lens unit 120 . The 360° viewing angle lens unit 110 is detachably connected to the regular lens unit 120 by connectors (not shown). A first optical axis O 1 of the regular lens unit 120 is perpendicular to a second optical axis O 2 of the 360° viewing angle lens unit 110 .

The regular lens unit 120 includes a lens group (not shown) which forms an entrance pupil surface 121 which receives a light incident from the 360° viewing angle lens unit 110 . The regular lens unit 120 further includes an image sensor 123 for sensing the light signals emitted from the lens group, and a number of necessary control components not shown in the figures. The central axis of the lens group forms the first optical axis O 1 . The image sensor 123 , such as a charge coupled device (CCD), or a complementary metal oxide semiconductor (CMOS) is provided at the focus location of the lens group.

The 360° viewing angle lens unit 110 includes, from the object side to the image side, a 360° viewing angle lens 10 , a relay lens 12 , and a reflective element 14 .

The 360° viewing angle lens 10 is made of a light permeable material, such as optical glass, or transparent resin. The 360° viewing angle lens 10 is symmetrically concentric around the second optical axis O 2 and includes an annular incident surface S 1 , an annular first reflective surface S 2 , a circular second reflective surface S 3 , and a circular emitting surface S 4 . The incident surface S 1 is externally symmetrically concentric to the first reflective surface S 2 , while the emitting surface S 4 is externally symmetrically concentric to the second reflective surface S 3 . The incident surface S 1 and the emitting surface S 4 oppositely extend along the second optical axis O 2 .

Correspondingly, the annular incident surface S 1 is symmetrically concentric around the second optical axis O 2 , and includes, from the object side to the image side of the lens unit 110 , a first circular edge 101 and a second circular edge 102 . The annular incident surface S 1 tilts to the second optical axis O 2 at a predetermined angle. The diameter of the first circular edge 101 is smaller than that of the second circular edge 102 . With reference to a direction from the object side to the image side, the radius of the curvature of the annular incident surface S 1 is positive. The annular incident surface S 1 is a convex surface projecting to the object side along the second optical axis O 2 . Thus, image light from 360° around the surface can enter the annular incident surface S 1 before entering the viewing angle lens 10 . In the present embodiment, the image light emitted in an area formed as measured from −10° to 40° relative to a line perpendicular to the second optical axis O 2 , can hit the annular incident surface S 1 .

Note that in other embodiments, the annular incident surface S 1 may be an extended rotation free-form surface that is formed by the rotation of a line segment of any shape about the second optical axis O 2 of rotational symmetry.

The first reflective surface S 2 is symmetrically concentric around the second optical axis O 2 , and includes, from the image side to the object side of the lens unit 110 , a third circular edge 103 and a fourth circular edge 104 . The first reflective surface S 2 tilts to the second optical axis O 2 at a predetermined angle, along a direction substantially opposite to the projecting direction of the incident surface S 1 . The diameter of the third circular edge 103 is smaller than that of the fourth circular edge 104 . The diameter of the fourth circular edge 104 is substantially equal to that of the second circular edge 102 . With reference to a direction from the object side to the image side, the radius of the curvature of the first reflective surface S 2 is positive. The first reflective surface S 2 is a convex surface projecting to the image side along the second optical axis O 2 . The outer surface of the first reflective surface S 2 is coated with a reflective film for efficiently and sufficiently reflecting the image light from the first reflective surface S 2 to the second reflective surface S 3 .

The second reflective surface S 3 is symmetrically concentric around the second optical axis O 2 and coaxial with the incident surface S 1 . The periphery of the second reflective surface S 3 is joined together with the first circular edge 101 of the incident surface S 1 . The second reflective surface S 3 also has a vertex on the second optical axis O 2 of rotational symmetry. With reference to a direction from the object side to the image side, the radius of the curvature of the second reflective surface S 3 is negative. The second reflective surface S 3 is a concave surface which is closed to the image side along the second optical axis O 2 . The outer surface of the second reflective surface S 3 is also coated with a reflective film for efficiently and sufficiently reflecting the image light from the second reflective surface S 3 to the emitting surface S 4 .

The emitting surface S 4 is symmetrically concentric around the second optical axis O 2 and coaxial with the first reflective surface S 2 . The periphery of the emitting surface S 4 is joined together with the third circular edge 103 of the first reflective surface S 2 . With reference to a direction from the object side to the image side, the radius of the curvature of the emitting surface S 4 is positive. The emitting surface S 4 is a convex surface projecting to the image side along the second optical axis O 2 . The emitting surface S 4 is configured for refracting and focusing the image light reflected from the second reflective surface S 3 .

A connecting surface 105 shaped as a substantially plane is defined between the fourth circular edge 104 and the second circular edge 102 . The diameter of the connecting surface 105 is larger than the diameter of the fourth circular edge 104 and the second circular edge 102 .

The relay lens 12 has positive refractive power for condensing the image light output from the emitting surface S 4 . The relay lens 12 includes a first surface S 5 concave toward the object side for light incident from the emitting surface S 4 of the 360° viewing angle lens 10 , and a second surface S 6 also convex to the image side for light emitting to the reflective element 14 . With reference to the direction from the object side to the image side, the radius of the curvature of the first surface S 5 is negative, while the radius of the curvature of the second surface S 6 is positive. Either one of the first surface S 5 or the second surface S 6 is aspheric. In this embodiment, the relay lens 12 is made of plastic, to lower the cost and weight.

The reflective element 14 is a mirror or a reflecting prism, and configured for reflecting the image light emitted from the relay lens 12 to the entrance pupil surface 121 of the regular lens unit 120 . In this embodiment, the reflective element 14 is a mirror. The angle between the first optical axis O 1 and a reflective surface of the reflective element 14 is 45°, the same as that between the second optical axis O 2 and the reflective surface. In other embodiments, the angle between the first optical axis O 1 or the second optical axis O 2 and the reflective surface may not be limited in 45°, but can be alternated as, e.g. 30° or 60°.

The image light is refracted into the interior of the 360° viewing angle lens 10 at a random point on the annular incident surface S 1 and then is reflected on the first reflective surface S 2 . The light reflected from the first reflective surface S 2 is further reflected by the second reflective surface S 3 to the emitting surface S 4 . The relay lens 12 condenses the light emitted from the emitting surface S 4 . Then the light is further reflected by the reflective element 14 . As a result, the image light may enter into the entrance pupil surface 121 of the regular lens unit 120 to form an image on the image sensor 123 . Sequentially, a landscape in full-360° angle-in-view is acquired by the 360° viewing angle lens 10 , once converted to an electric signal by the image sensor 123 of the regular lens unit 120 , and can be displayed on a display device, e.g. a liquid crystal display (LCD), or a cathode-ray tube (CRT).

Detailed examples of the optical lens system 100 using the 360° viewing angle lens 10 are given below with an accompany table 1 and table 2, but it should be noted that the optical lens system 100 is not limited by these examples. Listed below are the symbols used in these detailed examples:

R: radius of curvature;

Nd: refractive index of lens; and

D: displacement between one center of one surface and another center of another surface next to the one surface on the second optical axis O 2 ;

Vd: Abbe number.

In this embodiment, each surface of the 360° viewing angle lens 10 and the relay lens 12 is an aspherical surface. The aspherical surface is shaped according to the formula:

x = ch 2 1 + 1 - ( k + 1 ) ⁢ c 2 ⁢ h 2 + ∑ ⁢ Aih i

where h is a height from the optical axis of the 360° viewing angle lens 10 or the relay lens 12 to the aspherical surface, c is a vertex curvature, k is a conic constant, and Ai are i-th order correction coefficients of the aspherical surfaces. For example, A 4 is the 4th order aspherical coefficient of the aspherical surfaces, A 6 is the 6th order aspherical coefficient of the aspherical surfaces. The aspherical coefficient of the 360° viewing angle lens 10 and the relay lens 12 are shown in table 2:

While various exemplary have been described, it is to be understood that the disclosure is not limited thereto. To the contrary, various modifications and similar arrangements (as would be apparent to those skilled in the art) are intended to also be covered. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.