Led lens and light emitting device using the same

An LED lens having an axis of rotational symmetry, comprising:

• a light emitting surface being an aspheric surface including a first recession portion disposed at the center of the light emitting surface, and a convex portion connected to the outer periphery of the first recession portion;
• a light incident surface constituting a cavity having an opening, wherein a center of the baseline of the opening represents an incident origin, the light incident surface including:
• a first optically active area being disposed at a center of the light incident surface, wherein the first optically active area comprises a second recession portion;
• a second optically active area connected with the first optically active area, wherein the second optically active area forms a concave surface facing toward the incident origin;
• and
• an optical path conversion point disposed at a junction between the first optically active area and the second optically active area;
• and
• a bottom surface extended from the light incident surface and connected to the light emitting surface;
• wherein the LED lens satisfies the following conditions:
• L
• t
• /
• R
• e
• ≦
• 0.4
• ;
• R
• ir
• /
• R
• i
• ≦
• 0.3
• ;
• and
• 0.6
• ≤
• OI
• _
• 0
• ×
• tan
• 
• 
• θ
• 0
• S
• ir
• <
• 1
• ;
• wherein, Lt represents a maximum distance from an arbitrary point on the light emitting surface to the light incident surface or the bottom surface along the direction parallel with the axis of rotational symmetry;
• Re represents a diameter of the light emitting surface;
• Rir represents a diameter of the light incident surface at the optical path conversion point;
• Ri represents a diameter of the light incident surface;
• OR0 represents a distance from the incident origin to the point of intersection between the light incident surface and the axis of rotational symmetry;
• θ0 represents an included angle between the axis of rotational symmetry and a connecting line from the incident origin to the optical path conversion point;
• and Sir represents a distance from the optical path conversion point to the point of intersection between the light incident surface and the axis of rotational symmetry along the optical surface of first optically active area;
• wherein, θ represents an included angle between the axis of rotational symmetry and a connecting line from the incident origin to the arbitrary point on the light incident surface;
• wherein, in the range of θ<θ0, a distance from the incident origin to the light incident surface increases as 0 increases;
• wherein, in the range of θ0≦θ≦45°, the distance from the incident origin to the light incident surface decreases as the angle θ increases.