Optical lens assembly

A projection lens, comprising a first lens element, a second lens element, a third lens element, a fourth lens element, and a fifth lens element sequentially along an optical axis from a first side to a second side, wherein the first side is a light exit side, the second side is a light incident side, and each of the first lens element to the fifth lens element comprises a first side surface facing the first side and allowing imaging rays to pass through, and a second side surface facing the second side and allowing the imaging rays to pass through, wherein

• an optical axis region of the second side surface of the first lens element is convex;
• an optical axis region of the second side surface of the second lens element is concave;
• the projection lens satisfies a following conditional expression:
• TL/BFL≥4.400, where TL is a distance on the optical axis from the first side surface of the first lens element to the second side surface of the fifth lens element, BFL is a distance on the optical axis from the second side surface of the fifth lens element to a reference surface, and the reference surface is a light-emitting surface;
• the first lens element has positive refracting power;
• the second lens element has negative refracting power;
• the third lens element has positive refracting power;
• the fourth lens element has positive refracting power;
• the fifth lens element has negative refracting power;
• lens elements of the projection lens are only the first lens element to the fifth lens element described above;
• wherein the periphery region of the second side surface of the first lens element is defined as a region located radially outside of a farthest transition point from the optical axis to an optical boundary of the second side surface of the first lens element, the transition point is an intersection point where the second side surface of the first lens element meets a tangent to the second side surface of the first lens element that is perpendicular to the optical axis, and the optical boundary of the second side surface of the first lens element is defined as a point at which a radially outermost marginal ray passing through the second side surface of the first lens element intersects the second side surface of the first lens element;
• wherein when the second side surface of the first lens element has no transition point, the optical axis region of the second side surface of the first lens element is defined as a region of 0%-50% of a distance between the optical axis and the optical boundary of the second side surface of the first lens element, and the periphery region of the second side surface of the first lens element is defined as a region of 50%-100% of the distance between the optical axis and the optical boundary of the second side surface of the first lens element.

A projection lens, comprising a first lens element, a second lens element, a third lens element, a fourth lens element, and a fifth lens element sequentially along an optical axis from a first side to a second side, wherein the first side is a light exit side, the second side is a light incident side, and each of the first lens element to the fifth lens element comprises a first side surface facing the first side and allowing imaging rays to pass through, and a second side surface facing the second side and allowing the imaging rays to pass through, wherein

• the first lens element has positive refracting power;
• a periphery region of the first side surface of the fourth lens element is convex;
• the projection lens satisfies a following conditional expression:
• TL/BFL≥4.400, where TL is a distance on the optical axis from the first side surface of the first lens element to the second side surface of the fifth lens element, BFL is a distance on the optical axis from the second side surface of the fifth lens element to a reference surface, and the reference surface is a light-emitting surface;
• the second lens element has negative refracting power;
• the third lens element has positive refracting power;
• the fourth lens element has positive refracting power;
• the fifth lens element has negative refracting power;
• lens elements of the projection lens are only the first lens element to the fifth lens element described above;
• wherein the periphery region of the first side surface of the fourth lens element is defined as a region located radially outside of a farthest transition point from the optical axis to an optical boundary of the first side surface of the fourth lens element, the transition point is an intersection point where the first side surface of the fourth lens element meets a tangent to the first side surface of the fourth lens element that is perpendicular to the optical axis, and the optical boundary of the first side surface of the fourth lens element is defined as a point at which a radially outermost marginal ray passing through the first side surface of the fourth lens element intersects the first side surface of the fourth lens element;
• wherein when the first side surface of the fourth lens element has no transition point, the optical axis region of the first side surface of the fourth lens element is defined as a region of 0%-50% of a distance between the optical axis and the optical boundary of the first side surface of the fourth lens element, and the periphery region of the first side surface of the fourth lens element is defined as a region of 50%-100% of the distance between the optical axis and the optical boundary of the first side surface of the fourth lens element surface.