Electronic device
An electronic device includes an optical lens assembly. The optical lens assembly includes four lens elements which are, in order from an outer side to an inner side: a first lens element, a second lens element, a third lens element and a fourth lens element. The first lens element has negative refractive power. An outer-side surface of the first lens element is concave in a paraxial region thereof and has at least one convex critical point in an off-axis region thereof. The third lens element has positive refractive power. The fourth lens element has an inner-side surface being convex in a paraxial region thereof and having at least one concave critical point in an off-axis region thereof. The optical lens assembly has a total of four lens elements.
1 . An electronic device being a smartphone comprising an image capturing unit and a display unit, and the image capturing unit comprising:
an optical lens assembly comprising a total of four lens elements, the four lens elements being, in order from an outer side to an inner side, a first lens element, a second lens element, a third lens element and a fourth lens element; and
an image sensor disposed on an image surface of the optical lens assembly;
wherein the second lens element has positive refractive power, a curvature radius of an outer-side surface of the second lens element and a curvature radius of an inner-side surface of the second lens element have a same sign, a curvature radius of an outer-side surface of the fourth lens element and a curvature radius of an inner-side surface of the fourth lens element have a same sign, an axial distance between the third lens element and the fourth lens element is larger than an axial distance between the second lens element and the third lens element, the axial distance between the third lens element and the fourth lens element is smaller than a central thickness of the first lens element, and a central thickness of the second lens element is larger than a central thickness of the fourth lens element;
wherein the electronic device further comprises a projection unit, the image capturing unit, the projection unit and the display unit are disposed on a same side of the electronic device, and the projection unit comprises a light source configured for emitting visible light having a wavelength range of 400 nm to 750 nm or infrared light having a wavelength range of 750 nm to 1600 nm;
wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, an Abbe number of the i-th lens element is Vi, a refractive index of the first lens element is N1, a refractive index of the second lens element is N2, a refractive index of the third lens element is N3, a refractive index of the fourth lens element is N4, a refractive index of the i-th lens element is N1, and at least one lens element of the optical lens assembly satisfies the following condition:
8.0< Vi/Ni< 12.0, wherein i= 1, 2, 3 or 4.
2 . The electronic device of claim 1 , wherein the first lens element has an inner-side surface being concave in a paraxial region thereof.
3 . The electronic device of claim 1 , wherein the third lens element has an outer-side surface being convex in a paraxial region thereof.
4 . The electronic device of claim 1 , wherein the optical lens assembly further comprises an aperture stop disposed on the outer side of the second lens element.
5 . The electronic device of claim 1 , wherein outer-side surfaces and inner-side surfaces of the second lens element, the third lens element and the fourth lens element are aspheric.
6 . The electronic device of claim 1 , wherein the second lens element, the third lens element and the fourth lens element are made of plastic material.
7 . The electronic device of claim 1 , wherein at least one of an outer-side surface and an inner-side surface of at least one lens element of the optical lens assembly has at least one inflection point.
8 . The electronic device of claim 1 , wherein a curvature radius of an outer-side surface of the first lens element is R1, a curvature radius of an inner-side surface of the first lens element is R2, and the following condition is satisfied:
( R 1+ R 2)/( R 1− R 2)<0.70.
9 . The electronic device of claim 8 , wherein the curvature radius of the outer-side surface of the first lens element is R1, the curvature radius of the inner-side surface of the first lens element is R2, and the following condition is satisfied:
( R 1+ R 2)/( R 1− R 2)<0.40.
10 . The electronic device of claim 1 , wherein an absolute value of a curvature radius of an outer-side surface of the first lens element is smaller than an absolute value of a curvature radius of an inner-side surface of the first lens element.
11 . The electronic device of claim 1 , wherein a curvature radius of an inner-side surface of the third lens element and a curvature radius of the outer-side surface of the fourth lens element have a same sign.
12 . The electronic device of claim 1 , wherein a focal length of the third lens element and a focal length of the fourth lens element have different signs.
13 . The electronic device of claim 1 , wherein a focal length of the first lens element and a focal length of the fourth lens element have a same sign.
14 . An electronic device comprising:
an optical lens assembly comprising a total of four lens elements, the four lens elements being, in order from an outer side to an inner side, a first lens element, a second lens element, a third lens element and a fourth lens element;
wherein the second lens element has positive refractive power, a curvature radius of an outer-side surface of the second lens element and a curvature radius of an inner-side surface of the second lens element have a same sign, a curvature radius of an outer-side surface of the fourth lens element and a curvature radius of an inner-side surface of the fourth lens element have a same sign, an axial distance between the third lens element and the fourth lens element is larger than an axial distance between the second lens element and the third lens element, the axial distance between the third lens element and the fourth lens element is smaller than a central thickness of the first lens element, and a central thickness of the second lens element is larger than a central thickness of the fourth lens element;
wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, an Abbe number of the i-th lens element is Vi, a refractive index of the first lens element is N1, a refractive index of the second lens element is N2, a refractive index of the third lens element is N3, a refractive index of the fourth lens element is N4, a refractive index of the i-th lens element is Ni, and at least one lens element of the optical lens assembly satisfies the following condition:
8.0< Vi/Ni< 12.0, wherein i= 1, 2, 3 or 4;
wherein the refractive index of the fourth lens element is within the range of 1.669 to 1.700.
15 . The electronic device of claim 14 , wherein the first lens element has an inner-side surface being concave in a paraxial region thereof.
16 . The electronic device of claim 14 , wherein a curvature radius of an outer-side surface of the first lens element is R1, a curvature radius of an inner-side surface of the first lens element is R2, and the following condition is satisfied:
( R 1+ R 2)/( R 1− R 2)<0.70.
17 . The electronic device of claim 16 , wherein the curvature radius of the outer-side surface of the first lens element is R1, the curvature radius of the inner-side surface of the first lens element is R2, and the following condition is satisfied:
( R 1+ R 2)/( R 1− R 2)≤−0.36.
18 . The electronic device of claim 14 , wherein the Abbe number of the first lens element is V1, the Abbe number of the second lens element is V2, the Abbe number of the third lens element is V3, the Abbe number of the fourth lens element is V4, the Abbe number of the i-th lens element is Vi, the refractive index of the first lens element is N1, the refractive index of the second lens element is N2, the refractive index of the third lens element is N3, the refractive index of the fourth lens element is N4, the refractive index of the i-th lens element is Ni, and at least one lens element of the optical lens assembly satisfies the following condition:
8.0< Vi/Ni≤ 11.65, wherein i= 1, 2, 3 or 4.
19 . The electronic device of claim 14 , wherein an absolute value of a curvature radius of an outer-side surface of the first lens element is smaller than an absolute value of a curvature radius of an inner-side surface of the first lens element.
20 . The electronic device of claim 14 , wherein the second lens element, the third lens element and the fourth lens element are made of plastic material.