TWI453490B - Imaging lens - Google Patents

Description

Image capture lens

The present invention relates to imaging technology, and more particularly to an imaging lens.

With the continuous development of technology, electronic products are constantly moving towards light, short, and versatile. In electronic products, such as digital cameras and computers, there are already imaging devices, and even mobile phones and personal digital assistants (PDAs). The device also has the requirement of the image capturing device; for the convenience of carrying and the user-friendly requirements, the image capturing device not only needs to have good image quality, but also requires low cost, so as to effectively improve the application of the image capturing device. Sex.

In order to improve the image capturing effect of the image capturing device, correcting the aberration of the lens, the lens is usually designed to have a recurve shape, and the distance between the lens having the recurve shape and the adjacent lens is relatively long, so in order to ensure the lens There is no interference between them. It is necessary to provide spacers between adjacent lenses. Since the spacers must fill the gap between the edges of adjacent lenses, the spacers are thicker and some stray light is easy to avoid. The spacer enters the effective optical area of the lens, which affects the imaging of the lens.

In view of this, it is necessary to provide an image taking lens which can effectively reduce stray light.

An image taking lens comprising, in order from the object side to the image side, a first lens having a positive power, a second lens having a negative power, a third lens having a positive power, and a fourth lens having a positive power And an aperture disposed between the third lens and the fourth lens, the image taking lens satisfies the conditional formula: d ₂₃ < 1.1 × d ₃₄ and d ₃₄ <0.1×ψ 4; wherein d ₂₃ is the third lens a distance from a surface of the edge of the second lens to a surface of the second lens near the edge of the effective optical region of the third lens, d ₃₄ being the surface of the edge of the effective optical region of the fourth lens near the side of the third lens The distance from the surface of the third lens adjacent to the edge of the fourth lens, and ψ 4 is the edge diameter of the fourth lens.

An image taking lens comprising, in order from the object side to the image side, a first lens having a positive power, a second lens having a negative power, a third lens having a positive power, and a fourth having a negative power a lens, and a pupil disposed between the third lens and the fourth lens, the image capturing lens satisfying a conditional formula: d ₂₃ < 1.1 × d ₃₄ and d ₃₄ <0.1×ψ 4; wherein d ₂₃ is a third lens The distance from the surface of the edge of the second lens to the surface of the edge of the effective optical region of the second lens adjacent to the third lens, d ₃₄ is the edge of the effective optical region of the fourth lens near the side of the third lens The distance between the surface and the surface of the third lens adjacent to the edge of the fourth lens, and ψ 4 is the edge diameter of the fourth lens.

Compared with the prior art, the image taking lens of the present invention blocks the distance between the third lens and the adjacent second lens and the fourth lens, and blocks the aperture between the third lens and the fourth lens. Stray light, which effectively suppresses the miscellaneous in the image capturing lens astigmatism.

100‧‧‧Image lens

110‧‧‧ first lens

120‧‧‧second lens

130‧‧‧ third lens

140‧‧‧Fourth lens

150‧‧‧Light

S1‧‧‧ first surface

S2‧‧‧ second surface

S3‧‧‧ third surface

S4‧‧‧ fourth surface

S5‧‧‧ fifth surface

S6‧‧‧ sixth surface

S7‧‧‧ seventh surface

S8‧‧‧ eighth surface

1 is a schematic view showing the optical structure of the image taking lens of the present invention; and FIG. 2 is a light path diagram of the image taking lens of FIG.

Please refer to FIG. 1 , which is a schematic structural diagram of an image taking lens 100 according to a preferred embodiment of the present invention. The image taking lens 100 includes, in order from the object side to the image side, a first lens 110 having positive power, a second lens 120 having negative power, a third lens 130 having positive power, and having positive power or The fourth lens 140 of negative power.

The first lens 110 includes a first surface S1 facing the object side and a second surface S2 facing the image side. The first surface S1 has a spherical crown shape convex with respect to the object side, and the second surface S2 has a drum surface shape slightly convex with respect to the image side. The first surface S1 and the second surface S2 are both aspherical.

The second lens 120 includes a third surface S3 facing the object side and a fourth surface S4 facing the image side. The third surface S3 has a crescent shape concave with respect to the object side, and the fourth surface S4 has a crescent shape concave with respect to the image side. The third and fourth surfaces S3 and S4 are all aspherical.

The third lens 130 includes a fifth surface S5 facing the object side and a sixth surface S6 facing the image side. The fifth surface S5 has a crescent shape concave with respect to the object side, and the sixth surface S6 has a spherical crown shape convex with respect to the image side. The fifth and sixth surfaces S5 and S6 are all aspherical.

The fourth lens 140 includes a seventh surface S7 facing the object side and an eighth surface S8 facing the image side. The seventh surface S7 is in the shape of a crescent that is concave with respect to the object side, and the eighth surface S8 has an arcuate shape with respect to the concave side of the image side with respect to the concave side of the image side. The seventh and eighth surfaces S7 and S8 are all aspherical.

It can be understood that the surface of the first, second, third, and fourth lenses 110, 120, 130, and 140 near the object side may be referred to as an object side surface, and the surface near the image side is referred to as an image side surface.

In addition, the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 in the above embodiment may all be made of a plastic material to reduce the manufacturing cost of the image taking lens 100.

In addition, the image taking lens 100 further includes an aperture stop 150 disposed before the sixth surface S6 of the third lens 130 and the seventh surface S3 of the fourth lens 140.

When the image capturing lens 100 is imaged, the light is incident from the object side, and is sequentially imaged on the image forming surface 160 through the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140.

In order to prevent stray light from entering the optical path of the image taking lens 100, the distance between the effective optical area of the fourth lens 140 and the edge of the third lens 130 is shortened as much as possible, and the image taking lens 100 satisfies the conditional expression: (1) d ₂₃ < 1.1 × d ₃₄ ; wherein d ₂₃ is the distance between the surface of the third lens 130 near the edge of the second lens 120 to the surface of the second lens 120 near the edge of the effective optical region on the side of the third lens 130. d ₃₄ is the distance between the surface of the fourth lens 140 near the edge of the effective optical region on the side of the third lens 130 and the surface of the third lens 130 adjacent to the edge of the fourth lens 140.

The conditional expression (1) limits the distance of the edge of the third lens 130 to the effective optical area of the fourth lens 140 such that the edge of the third lens 130 is as close as possible to the fourth lens 140 so that the third lens 130 is disposed. The aperture 150 between the fourth lens 140 and the fourth lens 140 can effectively block light from the edge of the third lens 130.

Preferably, the image taking lens 100 satisfies the conditional expression: (2) d ₃₄ < 0.1 × φ 4

Where φ 4 is the edge diameter of the fourth lens 140.

The conditional expression (2) is based on the condition (1) to further ensure that the outer diameter of the fourth lens 140 is not excessively large.

In addition, the image taking lens 100 satisfies the conditional expression: (3); d ₃₄ < d _{34 c}

Wherein d _{34 c} is the distance between the center point of the seventh surface S7 of the fourth lens 140 to the plane of the edge of the third lens 130 on the side close to the fourth lens 140.

The conditional expression (3) ensures that the fourth surface S7 of the fourth lens 140 has a concave shape on the opposite object side, thereby ensuring that the thickness of the entire image taking lens 100 is small.

The image taking lens 100 will be further described below in accordance with the above conditions (1) to (3) in conjunction with the attached table. Where R is the radius of curvature of the corresponding surface, D is the distance along the optical axis from the corresponding surface to the latter surface (image side) (the length of the optical axis of the two surfaces), and Conic is the conical number of the surface of the lens.

Embodiment 1

The image taking lens 100 of the first embodiment satisfies the conditions listed in Table 1, and has an aperture value of 2.0, and the total length of the image taking lens 100 is 2.4 mm.

Among them, the aspherical surface can be expressed by the following formula:

Where z is the displacement value of the surface apex as the reference distance from the optical axis along the optical axis direction, c is the radius of curvature, h is the lens height, K is the conical constant (Coin Constant), and A4 is four times. The 4 th order Aspherical Coefficient A6 is a 6 th order Aspherical Coefficient, A8 is an 8 th order Aspherical Coefficient, and A10 is a ten-order aspherical Coefficient. 10 th order Aspherical Coefficient, A12 is a 12 th order Aspherical Coefficient.

The aspherical coefficients of the lenses in this embodiment are listed below: Table 2

Referring to FIG. 2, in the optical path diagram of the image taking lens 100 of the present invention, the stray light L is incident from the first lens 110, and is totally reflected by the fourth surface S4 of the second lens 120, and then by the second lens 120. The three surfaces S3 are reflected to the side of the second lens 120, and then reflected by the side of the second lens 120 into the third lens 130. Since the aperture 150 is disposed between the third lens 130 and the fourth lens 140, The stray light interception effectively avoids the influence of stray light on the imaging effect of the lens.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiments, and equivalent modifications or variations made by those skilled in the art in light of the spirit of the present invention are It should be covered by the following patent application.

100‧‧‧Image lens

110‧‧‧ first lens

120‧‧‧second lens

130‧‧‧ third lens

140‧‧‧Fourth lens

150‧‧‧Light

S1‧‧‧ first surface

S2‧‧‧ second surface

S3‧‧‧ third surface

S4‧‧‧ fourth surface

S5‧‧‧ fifth surface

S6‧‧‧ sixth surface

S7‧‧‧ seventh surface

S8‧‧‧ eighth surface

Claims (8)

An image taking lens comprising, in order from the object side to the image side, a first lens having a positive power, a second lens having a negative power, a third lens having a positive power, and a fourth lens having a positive power And an aperture disposed between the third lens and the fourth lens, the image taking lens satisfying the conditional expression: d ₂₃ <1.1×d ₃₄ and d ₃₄ <0.1×ψ 4; wherein d ₂₃ is the third lens a distance from a surface of the edge of the second lens to a surface of the second lens adjacent to the edge of the effective optical region on the side of the third lens, d ₃₄ being the surface of the edge of the effective optical region of the fourth lens near the side of the third lens The distance from the surface of the third lens adjacent to the edge of the fourth lens, and ψ 4 is the edge diameter of the fourth lens. The image taking lens of claim 1, wherein the image taking lens further satisfies a conditional expression: d ₃₄ <d _34c ; wherein d _34c is a center point of the object side surface of the fourth lens to the third lens The distance between the planes of the edges near one side of the fourth lens. The image taking lens according to any one of claims 1 to 2, wherein the first, second, third, and fourth lenses are aspherical lenses. The image taking lens of claim 3, wherein the first, second, third, and fourth lenses are made of a plastic material. An image taking lens comprising, in order from the object side to the image side, a first lens having a positive power, a second lens having a negative power, a third lens having a positive power, and a fourth having a negative power a lens, and a pupil disposed between the third lens and the fourth lens, the image capturing lens satisfying a conditional formula: d ₂₃ <1.1×d ₃₄ and d ₃₄ <0.1×ψ 4; wherein d ₂₃ is a third lens The distance from the surface of the edge of the second lens to the surface of the edge of the effective optical region of the second lens adjacent to the third lens, d ₃₄ is the edge of the effective optical region of the fourth lens near the side of the third lens The distance between the surface and the surface of the third lens adjacent to the edge of the fourth lens, and ψ 4 is the edge diameter of the fourth lens. The image taking lens of claim 5, wherein the image taking lens further satisfies a conditional expression: d ₃₄ <d _34c ; wherein d _34c is a center point of the object side surface of the fourth lens to the third lens The distance between the planes of the edges near one side of the fourth lens. The image taking lens according to any one of claims 5 to 6, wherein the first, second, third, and fourth lenses are aspherical lenses. The image taking lens of claim 7, wherein the first, second, third, and fourth lenses are made of a plastic material.