TW201100856A - Fixed focus lens - Google Patents

Abstract

A fixed focus lens includes a first lens group and a second lens group. The first lens group essentially consists of a first lens with a negative refractive power and a second lens with a positive refractive power in order of location from an object side to an image side. The second lens group is disposed between the first lens group and the image side. The second lens group essentially consists of a third lens with a positive refractive power, a fourth lens with a negative refractive power, and a fifth lens with a positive refractive power in order of location from an object side to an image side. The third lens satisfies the following condition: -150x10<SP>-6</SP> < (dn/dt) < 10<SP>-6</SP>, where dn denotes the variance in the index of refraction of the third lens, and dt denotes the variance in the temperature of the third lens.

Description

201100856 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to an optical lens, and more particularly to a fixed focus lens. [Prior Art] At present, digital image taking lenses on the market are designed to be miniature, high-resolution, and heavy (4). The image of the “mother drift” function, in the temperature rise or fall, the focal length of the class will also change, so the back focus must be adjusted to compensate, in order to maintain a certain optical port. Oral quality. However, in many applications of fixed-focus lenses, there is no mechanism to automatically adjust the back focus length. In this way, to ensure the image quality of the lens, the operating temperature will be limited to a narrow interval, resulting in considerable use. convenient. The so-called lens with the function of suppressing thermal drift means that the optical imaging quality of the lens can be maintained at a certain level regardless of the ambient temperature rise or decrease without the need to adjust the Q-back length. Figure 1 is a schematic diagram showing a conventional fixed focus lens design. The fixed focus lens 100 of the US Patent Publication No. US6940662 includes a first lens 1〇2 (negative refracting power), a second lens ι〇4 (positive refracting power), an aperture 112, which are arranged from the object side to the image side. The third lens 1〇6 (negative refracting power), the fourth lens (10) (positive refracting power), and the fifth lens 110 (positive refracting power). However, since the materials of the first to fourth lenses are all glass lenses and only the fifth lens is a plastic aspherical lens 201100856, it is impossible to achieve the purpose of quantification and cost reduction. Furthermore, the second lens 104 is a lenticular lens having a very high refracting power, so that the aperture cannot be further enlarged, and a glass material having a high refractive index must be used for reducing the aberration of the fixed-focus lens, which results in higher cost and tolerance Also more sensitive. Figure 2 is a schematic illustration showing a conventional fixed focus lens design. As shown in FIG. 2, the fixed-focus lens 200 of US Pat. No. 6,417,975 includes a first-peripheral (manufactured by the object side to the image side) 2 (贞 diopter), a second lens (positive flex luminosity), and an aperture 212. The third lens 2〇6 (positive refracting power), the fourth lens 208 (negative refracting power), and the fifth lens 21〇 (positive refracting power), and the fourth lens 2〇8 is glued to the fifth lens 210. However, in addition to the first lens 202 and the third lens 206 being plastic aspherical lenses, the rest are glass spherical lenses, so the number of glass lenses is too large to achieve the purpose of weight reduction and low cost. The one side of the lens 202 facing the object side (the first mirror surface of the fixed focus lens 2〇〇) is a concave surface, which significantly increases the risk of dust adhesion. Similar conventional designs, such as the US Patent Publication No. US Pat. No. 5,251,073, the publication No. US Pat. No. 6,995, 925, the US Patent Publication No. US20030161050, the Publication No. US20070223102, and the publication No. US20080266678, all disclose the design of the fixed-focus lens, however, any of the above In the conventional design, the lens shape and the overall configuration type cannot provide a fixed-focus lens with good image quality, light weight, wide viewing angle, high brightness and suppression of thermal drift. SUMMARY OF THE INVENTION The present invention provides a fixed focus lens point. Further understanding of other objects and advantages of the present invention will be obtained to avoid various disadvantages of the conventional design. The technique disclosed in the present invention provides a fixed focus lens for the above-mentioned or some or all of the embodiments, and the second lens group of the present invention. The first-peripheral, the w-the first lens group and the first lens two; =!=: the diopter of the mirror is positive. The second transmittance _: set = τ a third lens, a fourth lens, and a fifth transmission sequence are the positive, negative, and positive diopter of the 'plane, the fourth lens. The third lens satisfies the following condition: -150 Χ 10.6 &lt; (dn/dt) &lt; 10-6, wherein the 16 & third lens is a temperature change amount of the third lens. In the embodiment, the 'first lens, the second lens, the third lens and the fourth lens are each a plastic aspherical lens' and the fifth lens is a glass spherical lens. In one embodiment, the first lens, the second lens, the fourth lens, and the fifth lens are each a plastic aspherical lens, and the third lens is a glass spherical lens. In one embodiment, the total focal length of the first lens group is Ff, the total focal length of the second lens 201100856 group is Fr, and the fixed focus lens satisfies the following condition: Ff/Fr &lt; 0 ° in one embodiment, fourth The Abbe number of the lens is greater than 20 and less than 31. In one embodiment, the first lens is a convex-concave lens, the second lens is a lenticular lens, the third lens is a lenticular lens, the fourth lens is a double concave lens and the fifth lens is a lenticular lens, and the first lens A mirror surface facing the object side is a convex surface. Another embodiment of the present invention provides a fixed focus lens, which basically consists of a first lens, a second lens, and a third lens, which are sequentially arranged from an object side to an image side. a four-lens lens, the first lens is a convex-concave lens with negative refracting power, the second lens is a lenticular lens with positive refracting power, the second lens is a double concave lens with negative refracting power and the fourth lens is a positive diopter Double convex lens. The second lens satisfies the following condition: -150x10_6 &lt; (dn/dt) &lt; 10-6, where dn is the refractive index change amount of the second lens and dt is the temperature change amount of the second lens. With the design of each of the above embodiments, the fixed focus lens can effectively suppress the thermal drift phenomenon, ensuring that a certain image quality can be maintained in the operating temperature of the TC, and at the same time, having a long back focus, a wide viewing angle, and a lens. The overall weight is light and the manufacturing cost is low. Other objects and advantages of the present invention can be further understood from the technical features disclosed in the present invention. To enable the above and other objects of the present invention, 201100856 features and advantages The above and other technical contents, features and effects of the present invention will be described in detail below with reference to the embodiments of the present invention. In the following detailed description with reference to the drawings, the preferred embodiments will be clearly described. The directional terms mentioned in the following embodiments, such as "upper", "lower", "before", "after", " The left side, the "right", etc. are only referred to the orientation of the additional drawings. Therefore, the directional terminology used is intended to be illustrative and not limiting. FIG. 3 is an embodiment of the invention. A schematic diagram of the lens 1 ,, the fixed focus lens 10 is disposed between an object side and an image side, the image side is provided with an imaging surface 22 ′ and the imaging surface 22 can be, for example, a charge coupled device (CCD) image sense The detector or a complementary metal oxide semiconductor (CMOS) image sensor or the like is formed by a photosensitive element. As shown in FIG. 3, the fixed focus lens 10 includes a first lens group 12 and a second lens group. The first lens group 12 is adjacent to the object side and the second lens group 14 is adjacent to the image side. The first lens group 12 includes a first lens L1 and a second lens L2 arranged in sequence from the object side to the image side. The lens group 14 includes a third lens L3, a fourth lens L4, and a fifth lens L5 which are sequentially arranged from the object side to the image side. The first lens L1, the second lens L2, the third lens L3, and the fourth lens The diopter of L4 and the fifth lens 201100856 mirror L5 are negative, positive, positive, negative, and positive. In this embodiment, the first lens L1 is a convex-concave lens, and the second lens L2 is a meniscus lens, and the second lens L3 is a lenticular lens, and the fourth lens is a double concave lens and The fifth lens L5 is a lenticular lens. Further, the fixed focus lens 1 〇 can include an aperture stop 16 disposed between the first lens group 12 and the second lens group 4 to be separated. The first lens group 12 and the second lens group 14 are disposed, and a back focus element 18 is disposed between the fifth lens and the imaging surface 22. In the embodiment, the first lens L1, the second lens L2, and the third lens The L3 and the fourth lens L4 are both plastic aspherical lenses, and the fifth lens L5 is a glass spherical lens. Since the number of plastic lenses is much larger than the number of glass lenses (1), the weight can be reduced and the cost can be greatly reduced. Furthermore, in the present embodiment, the first lens L1 has a negative refracting power, so that the angle of view can be effectively increased, and a mirror surface facing the object side of the first lens L1 is convex, and dust adhesion can be avoided. In addition, since the second lens L2 is designed as a meniscus lens, the outer shape can effectively converge the light and enlarge the aperture. Furthermore, in order to effectively suppress the influence of the phenomenon of thether drift on the optical performance of the fixed-focus lens 10, in one embodiment, the material properties of the third lens L3 in the second lens group 14 can satisfy the following conditions: 〇χ1〇-6 &lt;(dn/dt)&lt;10_6, where dn is the refractive index change amount of the third lens and is the temperature change amount of the third lens, so dn/dt represents the refractive index under a certain temperature change variation. 201100856 In the practical example, in order to ensure a sufficient back focus length, when the total focal length of the first lens group 12 is Ff and the total focal length of the second lens group 14 is &amp;, the fixed focus lens 10 can be set to satisfy the following conditions: :

Ff / Fr &lt; 〇. In an embodiment, in order to effectively suppress chromatic aberration, the Abbe number of the fourth lens L4 in the second lens group 14 may be set to be greater than 20 and less than 31. Therefore, with the design of the above embodiment, the fixed focus lens has the following advantages, at least one of the following: I effectively suppresses the thermal drift phenomenon, and ensures a certain imaging can be maintained at the operating temperature of 〇t_6〇〇C. quality. 2. Long back focus. For example, if a 1/3" CMOS image sensing element is used, the back focus of the fixed focus lens 10 is greater than 6 mm. 3. Wide viewing angle. The angle of view of the fixed focus lens 10 can be greater than 80 degrees. Q 4 · Overall lens weight of the lens Light and low manufacturing cost. A lens design example of the fixed focus lens 10 of Fig. 3 is explained as follows. It is to be noted that the design values listed in Tables 1 and 2 below are not intended to limit the invention to any familiarity. Those skilled in the art, after referring to the present invention, may make appropriate changes to their parameters or settings, but still fall within the scope of the present invention 201100856.

<Table 1> Surface Curvature Radius (mm) Spacing (mm) Refractive Index Abbe Number S1 216.6444 1.5 1.531 55.9 S2 3.738178 3.391831 S3 -5.610453 2.1 1.632 23.4 S4 -4.664223 2.843906 Stop 〇〇0.9976116 S5 6.738147 2.247728 1.531 55.9 S6 -5.190564 0.408187 S7 -21.04354 0.7 1.632 23.4 S8 3.733374 0.7538742 S9 6.886021 1.906704 1.5891 61.1 S10 -6.886021 4.653 In Table 1, the spacing is the linear distance between two adjacent surfaces on the main axis. For example, the distance between the surfaces S1, ie the surface S1 Straight line distance from the surface S2 to the spindle. Further, in Table 1, the surfaces SI, S2 are the two surfaces of the first lens L1, the surfaces S3, S4 are the two surfaces of the second lens L2, and the surfaces S5, S6 are the two surfaces of the third lens L3, and the surfaces S7, S8 The both surfaces of the fourth lens L4, the surfaces S9, S10 are the two surfaces of the fifth lens 11 201100856 L5. The surface SI, S2, S3, S4, S5, S6, S7, S8 are aspherical, and the formula of the non-spherical surface is as follows: z =-. Cr -= + Α4Γ4 + ΑόΓ6 + ΑδΓ8 + Aior10 l + Vl-(l + k ) c2r2 _ In the above equation, z is the offset (sag) in the direction of the optical axis, and 〇 is the reciprocal of the radius of the osculating sphere, that is, the radius of curvature near the optical axis (such as SI in Table 1) , the reciprocal of the radius of curvature of S2, r is the aspherical height, that is, the height from the center of the lens to the edge of the lens, 〇k is a conic constant, and A4-A1() is the aspherical high-order coefficient (aspheric coefficient). The aspherical coefficients and k values of the surfaces S1-S8 are as shown in Table 2: &lt;Table 2&gt; Surface K 8 4 A6 As S1 0 0.0012781316 -3.2009007e-005 -1.6670962e-007 S2 0 0.0014605249 -3.5709866e-005 2.0372677e-005 S3 0 -0.0013061668 0.00010871437 -1.3706629e-005 S4 0 0.00064100658 5.0885442e-005 -4_2604853e-006 S5 0 -0.00040563668 -3.4804873e-005 4.9598385e-006 S6 0 0.005628683 -0.00053736521 4.2709988e-005 S7 0 0.0036793199 -0.0007029972 5.6226562e-005 S8 0 -0.00056571202 -0.00039502056 2.9394041e-005 12 201100856 Fig. 4 to Fig. 7D are optical data simulation diagrams of the fixed focus mirror of Fig. 3. Figure 4 is a fleld curvature diagram and a distortion diagram. The horizontal axis of the midfield curvature map represents the distance from the focal plane, the vertical axis represents the field from 〇 to the largest; the distortion _ horizontal axis represents the percentage of distortion. The vertical axis represents

biggest%. Figure 5 is an iaterai ray fan diagram, where the loose axis represents the different positions of the light passing through the aperture stop 16, the vertical axis represents the position where the light is incident on the image plane, and Figure 6 shows the relative illumination of the fixed focus lens. It can be clearly seen from FIGS. 4 to 6 that the fixed focus lens 10 of FIG. 3 has good image quality and brightness. Fig. 7A to Fig. 7D respectively show the focal plane shift of the fixed focus ^1 旳 at the 旳, machine, thief and machine temperature = as can be clearly seen from Fig. 7A to Fig. 7D, if it is 2 以 at room temperature. [The lower focal plane is the reference. The fixed-focus lens (7) has a focal plane offset of less than (10) when the temperature changes to (TC, 40t or 60 C), so the fixed-focus lens 10 can maintain good image quality when the temperature changes. FIG. 8 is a schematic diagram of a fixed focus lens 20 according to another embodiment of the present invention. The fixed focus lens 20 includes a - lens group 12 and a second lens group μ, and the first lens group 12 is adjacent to the object side and The second lens group 14 is adjacent to the image side, and the first lens group 12' includes a sixth lens u and a seventh lens L7 'second lens group 14 from the object sensing side, including from the object side to the image side. The sequential lens u, the ninth lens L9 and the tenth lens u〇, and the refractive rays t of the third to tenth ships are sequentially negative, positive, positive, negative, and positive. In this embodiment, the aperture light The barrier 16 is disposed between the first lens group 12 and the second lens group (4), 13 201100856, the sixth lens L6 is a convex-concave lens, the seventh lens L7 is a meniscus lens, and the eighth lens L8 is a lenticular lens 'ninth The lens L9 is a double concave lens and the tenth lens L10 is a lenticular lens. In this embodiment, the sixth lens L6 and the seventh lens are transparent. L7, ninth lens L9 and tenth lens L10 are both plastic aspherical lenses, and the eighth lens L8 is a glass spherical lens. Since the number of plastic lenses (4) is much larger than the number of glass lenses (1), the weight can be reduced and the cost can be greatly reduced. Furthermore, in the present embodiment, the sixth lens L6 has a negative refracting power, so that the angle of view can be effectively increased, and a mirror surface facing the object side of the six-lens L6 is convex, which can prevent dust from adhering. The seventh lens L7 is designed as a meniscus lens, and the outer shape can effectively converge the light to enlarge the aperture. Similarly, in order to effectively suppress the thermal drift phenomenon on the optical performance of the fixed focus lens 20, in an embodiment The material property of the eighth lens L8 in the second lens group 14' may satisfy the following condition: -150x10'6&lt;(dn/dt)&lt;10-6, wherein the refractive index change amount of the eighth lens is dt It is the temperature variation of the eighth lens, so dn/dt represents the refractive index variation under a certain temperature change. In an embodiment, in order to ensure a sufficient back focus length, when the total focal length of the first lens group 12' is Ff, Second lens group 14, total Distance is Fr, the focusing lens 20 may be set to satisfy the following conditions:

Ff/Fr &lt; In an embodiment, in order to effectively suppress chromatic aberration, the Abbe number of the ninth lens L9 in the second lens group 14, may be set to be greater than 2〇14 201100856 and less than 31 . A lens design example of the fixed focus lens 20 of FIG. 8 is shown below. The design values listed in Tables 3 and 4 below are not intended to limit the present invention, and any person skilled in the art can appropriately change its parameters or settings after referring to the present invention, but Still within the scope of the invention. <Table 3> 10.94538 3.562788 -5.257419 6.015508 6.43186 -10.01341 8.329921 5.03044 4.806493 -5.302248

Radius of curvature Surface (mm) S1 S2 S3 S4

Stop S5 S6 S7 S8 S9 S10 15 201100856 In Table 3, the surfaces S1 and S2 are the two surfaces of the sixth lens 269, the surfaces S3 and S4 are the two surfaces of the seventh lens L7, and the surface S5 is the eighth lens 1 The two surfaces of ^, the surfaces S7, S8 are the two surfaces of the ninth lens L9, the table

The surface S9 S10 is the two surfaces of the tenth lens. The surface, s'SlO is aspherical, and the formula of the non-spherical surface is as follows:

Z cr ^

Wl-(l + k)cV +A4r +A6r6+A8r8+A,〇r,0+AnR12...

In the above formula, 'Z is the offset of the optical axis direction (sag), c is the reciprocal of the radius of the osculating sphere, that is, the reciprocal of the radius of curvature near the optical axis, and r is the aspheric height. That is, from the lens's facet at the edge of the lens, k is a quadratic constant, and 八4_8 is an aspherical two-term coefficient. The aspherical coefficients and k values of the surfaces S1-S4 and S7-S10 are as shown in Table 4: &lt;Table IV&gt; Surface K ~·. A4 As Ai〇A12 S1 0 0.0044918997 -0.00019954178 6.9905468e-006 1.5389477e- 008 -1.0136241e-008 S2 0 ——— 0.0086446383 0.0001610428 -6.139348 le-005 5.093515e-006 9.4785248e-007 S3 0 0.00014130668 -6.3271515e-005 2.7970958e-006 1.681656e-007 S4 0 0.00042707896 1.0555399e-005 1.5607791 E-006 -2.2786669e-007 5.1120596e-008 S7 0 -0.00053091052 -3.632092e-005 -1.0084742e-006 2.1545709e-009 16 201100856 S8 0 -0.00059138544 -7.5622536e-005 -4.0807434e-006 2.0575552e-008 S9 0 -0.00088319783 -2.8299181e-005 -6.6890007e-007 1.1068132e-007 S10 0 0.0033763748 -5.9039274e-006 3.8270309e-006 4.357297e-007 -1.3848813e-008 Figure 9 to Figure 12D is the fixed focus of Figure 8. An optical data simulation of the lens 20. Figure 9 is a field curvature diagram and a distortion diagram, in which the horizontal axis of the field curvature map represents the distance from the focal plane, the vertical axis represents the field from the 〇 to the maximum; the horizontal axis of the distortion map represents the percentage of distortion, and the vertical axis represents the 〇 to The biggest field. 1 is a transverse ray sector diagram in which the horizontal axis represents the different positions of the light passing through the aperture stop 16, the vertical axis represents the position where the light is irradiated onto the image plane, and the U shows the contrast of the fixed focus lens 20, as shown in FIG. 1丨 It can be clearly seen that the fixed focus lens 20 of FIG. 8 has good image quality and brightness. Figures i2A to 12〇 respectively show the fixed-focus lens 10 at (TC, 20. (: m60 c temperature focal plane offset. It can be clearly seen from Figure 12A to the coffee, if it is suppressed at room temperature The focal plane is the reference, and the focal plane offset of the fixed-focus lens 10 when the temperature changes to 〇C, 4〇C or 6〇t is smaller than that. 'The temperature correction money (4) fixed focus class 2G is reduced well. According to another aspect of the present invention, the fixed-focus lens 30 of the fixed-focus lens 30 includes a 筮 违 违 T 11 11 11 11 11 透镜 透镜 透镜 L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L L The diopter of the eleventh lens of the eleventh lens is sequentially negative, positive, negative, and positive. In the embodiment, the aperture stop 16 is disposed between the eleventh lens LU and the twelfth lens L12. The eleventh lens L11 is a convex-concave lens, the twelfth lens L12 is a lenticular lens, the thirteenth lens L13 is a double concave lens, and the fourteenth lens L14 is a lenticular lens. In this embodiment, the eleventh lens L11, the thirteenth lens L13 and the fourteenth lens L14 are both plastic aspherical lenses, and the twelfth lens L12 is a glass spherical lens because 0 The number of plastic lenses (3) is much larger than the number of glass lenses (1), which can also reduce the weight and greatly reduce the cost. Similarly, a mirror surface facing the object side of the eleventh lens L11 is convex, which can avoid dust adhesion and is effective. Inhibiting the effect of the thermal drift phenomenon on the optical performance of the fixed-focus lens 30, in one embodiment, the material properties of the twelfth lens L12 can satisfy the following conditions: -15〇xl〇-6&lt;(dn/dt) &lt;l〇-6, where dn is the refractive index change amount of the twelfth lens and dt is the temperature change amount of the twelfth lens, so Θdn/dt represents the refractive index variation under a certain temperature change. In order to ensure a sufficient back focus length, when the focal length of the eleventh lens Li丨 is Ff, and the total focal lengths of the twelfth lens L12, the thirteenth lens L13, and the fourteenth lens L14 are F Γ, Fixed-focus lens 2 〇 can be set to meet the following conditions:

Ff/Fr &lt; 〇 〇 A lens design example of the fixed focus lens 30 of Fig. 13 is explained as follows. It should be noted that the design values listed in Tables 5 and 6 below are not intended to limit the scope of the present invention. The present invention may be adapted to any of its parameters or settings after reference to the present invention. Still belongs to the mouth of the invention. &lt;Table 5&gt; Surface————1. Curvature radius (mm) Spacing (mm) Refractive index Abbe number S1 378.5936 0.80192 1.531 55.9 S2 4.166894 9.234718 —----- Stop 〇〇-0.4417611 ---- --- S3 6.16726 2.017319 1.717 47.93 S4 -17.06603 2.387048 S5 -43.97862 1.098072 1.632 23.4 S6 2.261677 0.1567506 S7 2.867443 3.682692 ~----- 1.531 55.9 S8 -3.468333 2.31853 ---~~~--- In Table 5 The surfaces S1 and S2 are the two surfaces of the eleventh lens L11, the surfaces S3 and S4 are the two surfaces of the twelfth lens L12, and the surfaces S5 and % are the two surfaces of the thirteenth lens L13. The surfaces S7 and S8 are the fourteenth. Both surfaces of the lens L14. The surfaces SI, S5, S6, S7, and S8 are aspherical, and the formula for the 2011 20110856 aspheric surface is as follows: cr2 Z =——======+ Α4Γ4 + Aer6 + Asr8 + Aior10 + Ai2R12 l + Vl-(l + k)cV ... In the above equation, z is the offset (sag) in the direction of the optical axis, and c is the reciprocal of the radius of the osculating sphere, that is, the reciprocal of the radius of curvature near the optical axis, r The aspherical height, which is the south from the lens center to the lens edge, k is the quadratic constant, and A4-Ai2 is the aspheric high-order coefficient. The aspherical coefficients and k values of the surfaces SI, S5, S6, S7, and S8 are as shown in Table 6: &lt;Table VI&gt; Surface K a4 Ai〇A12 S1 -500 0.00071155867 -1.1182923e-005 1.5722926e-007 -3.7364437 E-010 1.355978e-01 S5 128.9989 -0.020191025 0.0026912714 -0.00036917428 2.1660502e-005 6.042275e-01 S6 -3.727476 -0.0077050281 0.001272394 -0.00012656653 9.8322344e-006 -5.283857e-01 S7 -4.541966 -0.0017594023 -8.2751341e-005 6.7080729 E-005 -3.8360612e-006 S8 -5.012382 -0.011487085 0.0014858823 -0.00014996526 7.6769765e-006 FIGS. 14 to 17D are optical data simulation diagrams of the fixed focus lens 3 of FIG. Figure 14 is a field curvature diagram and a distortion diagram, in which the horizontal axis of the field curvature map represents the distance from the focal plane, the vertical axis represents the field from the 〇 to the maximum; the horizontal axis of the distortion map represents the percentage of distortion, and the vertical axis represents the 〇 to The biggest field. Figure 20 201100856 is the transverse ray handle ' 'where the horizontal axis represents the different positions of the light passing through the aperture light i6, the vertical axis represents the position of the light surface to the image plane, and Figure 16 shows the relative contrast of the fixed head 3G, Figure 14 As can be clearly seen from Fig. 16, the fixed focus lens 3G of Fig. 13 has good image quality and brightness. 17A to 17D respectively show the focal plane shift amounts of the fixed focus lens 3 at 叱, 2〇〇c, 4〇 C, and 60 C degrees. It can be clearly seen from Fig. 17A to port d that if the focal plane lens 30 is changed in temperature at room temperature 2 (the focal plane at TC) (rC, 4 (the focal plane offset at rc or 6 均) It is less than 0.02mm, so the fixed focus lens can maintain good image quality when the temperature changes. With the design of each of the above embodiments, the fixed focus lens can effectively suppress the thermal drift phenomenon 'miscing in Gt>6 (TC operating temperature) (4) It can maintain a certain image quality' and at the same time has the advantages of long back focus, wide viewing angle, light weight of the overall structure of the lens and low manufacturing cost. However, the above is only the preferred embodiment of the present invention. It is not possible to use this invention to invent the real red face, that is, to test the patent scope of the present invention and the simple equivalent changes and modifications made by the invention, which are still within the scope of the patent of the present invention. The scope of the invention or the scope of the invention is not intended to limit the scope of the invention, and the scope of the invention is not intended to limit the scope of the invention. 20110 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing a conventional fixed-focus lens design. Figure 2 is a schematic view showing another conventional fixed-focus lens design. Figure 3 is a fixed focus according to an embodiment of the present invention. Fig. 4 to Fig. 7D are optical data simulation diagrams of the fixed focus lens of Fig. 3. Fig. 4 is a field curvature diagram and a distortion diagram, Fig. 5 is a lateral ray sector diagram, and Fig. 6 shows a relative illumination of the fixed focus lens. 7A to 7D respectively show the focal plane shift amount of the fixed focus lens at temperatures of 〇 ° C, 20 ° C, 40 ° C, and 60 ° C. FIG. 8 is another embodiment of the present invention. Fig. 9 to Fig. 12D are optical data simulation diagrams of the fixed focus lens of Fig. 8, wherein Fig. 9 is a field curvature diagram and a distortion diagram, Fig. 10 is a lateral ray sector diagram, and Fig. 11 shows a fixed focus lens. In contrast, FIGS. 12A to 12D respectively show focal plane shift amounts of the fixed focus lens 10 at temperatures of 〇°C, 20° C., 40° C., and 60° C. FIG. 13 is another embodiment of the present invention. Schematic diagram of the fixed focus lens. Fig. 14 to Fig. 17D are optical data simulation diagrams of the fixed focus lens of Fig. 13 Figure 15 is a horizontal ray sector diagram, Figure 16 shows the contrast of the fixed-focus lens, and Figures 17A to 17D show the fixed-focus lens at 〇 °C, 2 (TC, 40 ° C and 60 ° C, respectively). Focal plane offset at temperature. 22 201100856

[Main component symbol description] 10, 20, 30 fixed focus lens 12, 12, first lens group 14, 14, second lens group 16 aperture stop 18 back focus element 22 imaging surface 100 fixed focus lens 102, 104, 106 , 108 , 110 112 aperture 200 fixed focus lens 202 , 204 , 206 , 208 , 210 212 aperture L1 first lens L2 second lens L3 third lens L4 fourth lens L5 fifth lens L6 sixth lens L7 seventh lens L8 Eighth lens L9 Ninth lens lens 23 201100856 L10 Tenth lens L11 Eleventh lens L12 Twelfth lens L13 Thirteen lens L14 Fourteenth lens S1-S10 Lens surface

twenty four

Claims (1)

201100856 VII. Patent application scope: 1. A fixed-focus lens comprising: a first lens group 'the first lens group is basically arranged from the object side to the image side - the first lens and the second lens a lens, the diopter of the first lens is positive for the second lens; and the second lens group 'is disposed between the first lens group and the image side. The third lens, the fourth lens, and the fifth lens are arranged in sequence from the object side to the image side, and the diopter of the third lens, the fourth lens and the fifth Wei are positive in sequence. Negative, positive, and the third lens satisfies the following condition: -15〇xl〇'6&lt;(dn/dt) &lt;1〇'6; wherein the refractive index change amount of the third lens and dt is The amount of temperature change of the third lens. 2. The fixed focus lens of claim 2, wherein the first lens, the second lens, the third lens and the fourth lens are each a plastic aspherical lens and the fifth lens is A glass spherical lens. 3. The fixed focus lens of claim 2, wherein the first lens, the first lens, the fourth lens, and the fifth lens are each a plastic aspherical lens, and the third lens is A glass spherical lens. 4. The fixed focus lens of claim 1, wherein a total focal length of the first lens group is Ff, a total focal length of the second lens group is Fr, and 201100856 the fixed focus lens satisfies the following condition: Ff /Fr &lt; 0. 5. The fixed focus lens of claim 1, wherein the fourth lens has an Abbe number greater than 20 and less than 31. 6. The fixed focus lens of claim 1, wherein the first lens is a convex-concave lens, and the second lens is a meniscus lens, Ο The second lens is a lenticular lens, the fourth lens is a double concave lens and the fifth lens is a lenticular lens. The fixed-focus lens of claim 6, wherein a mirror surface of the first lens facing the object side is a convex surface. 8. The fixed focus lens of claim 1, further comprising: an aperture beam disposed between the first lens group and the second lens group; and a back focus element disposed on the fifth Between the lens and an image forming surface, the fixed-focus lens of claim 8, wherein the image forming surface is composed of a photosensitive member. j two types of fixed-focus lens 'the job lens is basically from the - object side two image side: a first lens arranged in a sequence, a second lens three convex and concave lens, ir, 'mirror is the first transmission with negative diopter - The lens is a lenticular lens with positive refracting power, a double concave lens of 'X=degree and the fourth lens is a convex lens, and the second lens satisfies the following conditions: 26 201100856 -15〇xlO'6&lt;(dn /dt)&lt;l〇·6; wherein dn is the refractive index change amount of the second lens and dt is the temperature change amount of the second lens. 11. The fixed focus lens of claim 10, wherein the first lens, the third lens and the fourth lens are each a plastic aspherical lens, and the second lens is a glass spherical lens. 12. The fixed focus lens of claim 10, wherein a focal length of the first lens is Ff, and a total focal length of the second lens, the third lens, and the fourth lens is Fr, and The fixed focus lens satisfies the following conditions: Ff/Fr&lt;0. 13. The fixed focus lens of claim 10, wherein a mirror surface of the first lens facing the object side is a convex surface. 14. The fixed focus lens of claim 10, further comprising: an aperture stop disposed between the first lens and the second lens; and a back focus element disposed on the fourth lens Between an image plane and an image. 15. The fixed focus lens of claim 14, wherein the imaging surface is formed by a photosensitive element. 27