Plastic rod lens, rod lens array, rod lens plate, image sensor and printer
View Patent ↗A plastic rod lens having a cylindrical shape with a radius R including a central axis; and an outer peripheral portion, wherein a refractive index n D decreases from the central axis to the outer peripheral portion, and the following requirements (1) to (3) are met: 43≦ν 1 ≦60 (1) |{ n A ×ν A /( n A −1)}−{ n B ×ν B /( n B −1)}|<5 (2) n 0 −n 1 ≧0.01 (3) wherein n 1 , n 0 , n A , and n B represent refraction index n D in the outer peripheral portion, at the center, and at arbitrary points A and B, respectively, and ν 1 , ν A , and ν B represent Abbe number ν in the outer peripheral portion, and at the arbitrary points A and B, respectively.
1. A plastic rod lens having a cylindrical shape with a radius R comprising:
a central axis; and
an outer peripheral portion,
wherein a refractive index n D decreases from the central axis to the outer peripheral portion, and the following requirements (1) to (3) are met:
43≦ν 1 ≦60 (1)
|{ n A ×ν A /( n A −1)}−{ n B ×ν B /( n B −1)}|<5 (2)
n 0 −n 1 ≧0.01 (3)
wherein n 1 , n 0 , n A , and n B represent the refractive index n D in the outer peripheral portion, at the center, and at arbitrary points A and B, respectively, and ν 1 , ν A , and ν B represent Abbe number v in the outer peripheral portion, and at the arbitrary points A and B, respectively,
wherein a polymer constituting the plastic rod lens contains the following building blocks (A) to (C):
(A) a (meth)acrylate unit containing an alicyclic ring and/or a heterocyclic ring,
(B) a monomer unit containing an aromatic ring, and
(C) a fluorinated alkyl(meth)acrylate unit, and
wherein a content of the building block (B) in the polymer increases continuously towards the outer peripheral portion at least within a distance range of 0.8 R to R from the central axis.
2. The plastic rod lens according to claim 1 , wherein the polymer further contains a building block (D) which is a methyl(meth)acrylate unit.
3. The plastic rod lens according to claim 2 , wherein a polymer containing the building block (A) is contained at least within a distance range of 0 to 0.5 R from the central axis;
a polymer containing the building block (D) is contained at least within a distance range of 0 to R from the central axis; and
a polymer containing the building blocks (B) and (C) is contained at least within a distance range of 0.5 R to R from the central axis.
4. The plastic rod lens according to claim 2 , wherein a content of the building block (B) in the polymer increases continuously towards the outer peripheral portion at least within a distance range of 0.8 R to R from the central axis.
5. A rod lens array comprising one or more lines of plastic rod lenses of claim 1 arranged in parallel.
6. The rod lens array according to claim 5 satisfying the following requirements:
Tc (630)− Tc (470)≦0.3 mm, and
Tc (525)≦12 mm,
wherein Tc(λ) represents a conjugation length of the rod lens array when light wavelength is λ nm.
7. A printer comprising the rod lens array of claim 5 .
8. An image sensor comprising the rod lens array of claim 5 .
9. A rod lens plate comprising plastic rod lenses of claim 1 arranged two-dimensionally.
10. An image sensor comprising the rod lens plate of claim 9 .
11. A printer comprising the rod lens plate of claim 9 .