CN107765351A - Lens and lens assembly - Google Patents

Abstract

The present invention relates to a lens, comprising a refractive portion and an edge portion. The refractive portion has a negative refractive power, and the edge portion surrounds the refractive portion and is located outside the effective refractive area of the lens. The edge portion has a plurality of recesses, and the recesses are arranged in a mirror-symmetrical manner relative to a symmetry plane containing the optical axis of the lens. The maximum thickness ratio of the lens is greater than 2.5. When a fluid is injected into a mold cavity from a gate, the wavefront of the fluid can reach the opposite side of the gate more evenly, and will not collide before reaching the opposite side of the gate, so as to reduce the chance of a bonding line being generated in the refractive portion of the lens, thereby ensuring the optical quality of the lens.

Description

lens

technical field

The present invention relates to an optical element, and in particular to a lens with a plurality of concave structures on its surface.

Background technique

The lens is a basic and indispensable optical element in the optical system, and it plays an extremely critical and important role in the optical imaging lens. The imaging quality of an optical imaging lens is directly related to the quality of the lens it uses, so how to manufacture a lens with good quality has become one of the important issues in manufacturing an optical system.

In order to cope with the continuous improvement of the performance requirements of today's optical imaging lenses, it is necessary to use a lens with a large thickness ratio in the lens, which can be understood as the ratio of the maximum thickness to the minimum thickness of the lens in the direction parallel to the optical axis is relatively large. However, when the injection molding process is used to manufacture a lens with a large thickness ratio, and when the fluid is injected from the gate on the side of the lens into the mold cavity used to form the lens, it is easy to cause the fluid flow rate in each area of the cavity to be uneven. Instead, the wavefronts of the fluid impinge to create weld lines in the finished lens. This is because the flow velocity of the fluid in the cavity corresponding to the thicker lens is greater than the flow velocity of the fluid in the cavity corresponding to the thinner lens, so that the wave fronts of the fluid collide before reaching the opposite side of the gate. When this combination line extends into the effective refractive zone of the lens, it will have a bad influence on the imaging quality of the lens.

Contents of the invention

The invention provides a lens with good optical quality.

An embodiment of the invention provides a lens, including a refractive portion and an edge portion. The diopter has a negative diopter, and the edge surrounds the diopter and is located outside the effective diopter area of the lens. The edge portion has a plurality of depressions which are arranged mirror-symmetrically with respect to a plane of symmetry containing the optical axis of the lens. The ratio of the maximum thickness of the lens in the direction parallel to the optical axis divided by the minimum thickness of the lens in the direction parallel to the optical axis or the thickness at the optical axis is optionally greater than 2.5.

In the lens of the embodiment of the present invention, the diopter has a negative diopter, the maximum thickness ratio of the lens in a direction parallel to the optical axis is greater than 2.5, and the lens has a plurality of depressions around the edge of the diopter. In this way, when the lens is produced by the injection molding process, the convex land on the mold that is complementary to the concave shape of the lens can block the flow rate of the fluid, so that the fluid injected into the mold cavity corresponds to the thicker edge in the mold cavity The flow velocity in the region of the refraction portion is not too much greater than the flow velocity in the region of the mold cavity corresponding to the thinner refractive portion. Accordingly, when the fluid is injected into the mold cavity from the gate, the wave front of the fluid can reach the opposite side of the gate evenly, and will not collide before reaching the opposite side of the gate, so as to reduce the flexure in the lens. Opportunities for the optical part to generate bonding lines, whereby the optical quality of the lens can be ensured.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with reference to the accompanying drawings.

Description of drawings

1A is a schematic cross-sectional view of a lens according to an embodiment of the present invention;

FIG. 1B is a schematic perspective view of the lens of FIG. 1A;

Fig. 1C is a schematic top view of the lens of Fig. 1A;

2 is a schematic cross-sectional view of a mold for manufacturing the lens of FIG. 1A;

Figure 3 is a wavefront distribution diagram of the material of a control group of lenses at different time points in the injection molding process;

Figure 4 shows the bonding lines produced when the lens of Figure 3 is formed;

FIG. 5 is a diagram showing the wavefront distribution of the material of the lens in FIG. 1A at different time points during the injection molding process.

Explanation of reference signs:

100: lens;

110, 110': Refractive part;

112: first surface;

114: second surface;

200: edge;

210: depression;

211: chamfering;

212: Centrifugal surface;

213: plane;

214: proximal surface;

215: bottom;

216: bottom surface;

300: mould;

310: the first mold;

320: the second mold;

322: Boss;

330: mold cavity;

340: gate;

A: optical axis;

C: bonding line;

F1, F2, F3, F4: wave front;

F1', F2', F3', F4': wave front;

H3: minimum distance;

L: connect;

P: symmetrical plane;

R: distance;

T1: maximum thickness;

T2: thickness;

T3: minimum thickness;

W1, W2: width;

Z: sector area;

θ1: first inclination angle;

θ2: second inclination angle;

φ: expansion angle.

Detailed ways

Fig. 1A is a schematic cross-sectional view of a lens according to an embodiment of the present invention, Fig. 1B is a schematic perspective view of the lens in Fig. 1A, and Fig. 1C is a schematic top view of the lens in Fig. 1A, wherein the cross-section of Fig. 1A is along Fig. 1B and Fig. 1A The cross section of line I-I in Fig. 1C. Please refer to FIG. 1A to FIG. 1C , the lens 100 of this embodiment includes a diopter 110 and an edge portion 200 . The diopter 110 has a negative diopter, so that light rays passing through the diopter 110 are more deflected toward the direction of divergence. The edge portion 200 surrounds the refraction portion 110 and is located outside the effective refraction zone of the lens 100 . The effective refractive area means that when the light passes through this area, it can be effectively focused or astigmatized by the curved surface of the lens 100 (such as the first surface 112 and the second surface 114 of the refractive part 110), such as with the lens 100 The optical axis A is symmetrically focused or astigmatic. The effective refractive area is, for example, the area enclosed by the first surface 112 , the second surface 114 and two dashed lines shown in FIG. 1A . In addition, when the lens 100 is applied in an imaging lens, the clear aperture (clear aperture, CA) of the first surface 112 can be exactly the range defined by the intersection of the first surface 112 and two dashed lines, or be smaller than the range defined by the first surface 112 and the range defined by the intersection of the two dashed lines; and the clear aperture of the second surface 114 may be exactly the range defined by the second surface 114 and the intersection of the two dashed lines, or smaller than the range defined by the intersection of the second surface 114 and the two dashed lines. That is to say, as long as the clear aperture is within the range of the effective refractive zone, the imaging lens can normally display the imaging effect. In addition, the diopter 110 is the part of the lens 100 located in the effective refraction zone.

In this example, the edge portion 200 includes six concentrically designed concentrically shaped concavities 210 that are approximately the same in shape, equidistant around the optical axis, and each of the plurality of concavities 210 is approximately truncated quadrangular pyramid. In addition, as shown in FIG. 1A and FIG. 1C , the distribution of the depressions 210 is mirror-symmetric along the symmetry plane P of the optical axis A of the lens 100 . The aforesaid symmetry refers especially to the distribution of the depressions 210 on the lens surface, and although the entire lens may be mirror symmetric, it is not limited to mirror symmetry. Due to the symmetry, the number of the recesses 210 can be even. In addition, as shown in the figure, the plane of symmetry P must simultaneously penetrate the center line of the width direction of the feed port and the optical axis of the lens; moreover, the plane of symmetry P must also be divided into two equal parts along the width direction of the lens 100, as mentioned above The width direction is roughly perpendicular to the initial feeding direction.

In this embodiment, each depression 210 is a polyhedral depression, such as a frustum of pyramid, more specifically, the depression of the frustum of pyramid is, for example, a depression of a truncated quadrangular pyramid. However, in other embodiments, each depression 210 may also be a triangular pyramid depression, a polygonal pyramid depression, a cube depression, a cuboid depression or other polyhedron depressions. In addition, the depression 210 is not only a polyhedral depression, but also a hemispherical depression or a semi-ellipsoid. However, considering the material flow factor during the manufacturing process, its design is relatively difficult, and its principle will be described later.

In this embodiment, as shown in FIG. 1B , there is a chamfer 211 between at least two adjacent planes 213 of the polyhedral depression. In addition, in this embodiment, the bottom 215 of the truncated pyramid depression is substantially rectangular.

Furthermore, in this embodiment, the maximum thickness ratio of the lens 100 is greater than 2.5. In this example, the maximum thickness ratio refers to the ratio obtained by dividing the maximum thickness T1 of the lens 100 in a direction parallel to the optical axis A by the minimum thickness of the lens 100 in the same direction. In addition, the maximum thickness ratio also refers to the ratio obtained by dividing the maximum thickness T1 of the lens 100 in a direction parallel to the optical axis A by the thickness T2 on the optical axis A. Referring to FIG.

In this embodiment, the material of the lens 100 is plastic and is produced by an injection molding process, but the material and process are not limited thereto.

FIG. 2 is a schematic cross-sectional view of an example of a mold for manufacturing the lens of FIG. 1A . Referring to FIG. 1A to FIG. 1C and FIG. 2 , when the mold 300 is closed, the shape of the mold cavity 330 generated between the first mold 310 and the second mold 320 of the mold 300 is the shape of the lens 100 . In this embodiment, when the plastic is injected into the mold 300 and cured, the plastic will form the lens 100 . The second mold 320 has a plurality of protrusions 322 , the shapes of the protrusions 322 are complementary to those of the recesses 210 of the lens 100 , so that after the injection molding, the positions of the protrusions 322 will form the corresponding recesses 210 .

FIG. 3 is a graph showing the wavefront distribution of a control group of lenses at different time points during the injection molding process. It can be seen from the figure that it does not have the depression 210 as shown in FIG. 1A (that is, its mold does not have the boss 322 as shown in FIG. 2 ). At 0.781, 0.794, 0.802 and 0.810 seconds after the material is injected in the injection molding process, the wavefront distribution of the material is shown as wavefront F1, wavefront F2, wavefront F3 and wavefront F4. And FIG. 4 shows a schematic diagram of the bonding line generated when the lens of FIG. 3 is formed. FIG. 5 is a graph showing the wavefront distribution of the material of the lens 100 in FIG. 1A at different time points during the injection molding process. The wavefront distribution of the material at 0.02414, 0.03152, 0.03803 and 0.04116 seconds after the injection molding process is shown as wavefronts F1' to F4'. One way to interpret the term top-opening front is the outline of the leading edge of the material as it advances.

Please refer to FIG. 3 first. When the lens without the concave 210 as shown in FIG. 1A is injection molded, since the thickness of the edge portion is greater than the thickness of the refractive portion, the thickness corresponding to the edge portion in the mold cavity is greater than the corresponding thickness in the mold cavity. In the thickness of the refractive part. This causes the material injected into the cavity to flow at a higher velocity at the edges than in the center. Among them, it can be clearly seen from wavefront F3 and wavefront F4 that wavefront F3 has been divided into left and right sub-wavefronts, and these two sub-wavefronts will collide with each other, and from wavefront F4, two colliding sub-wavefronts can also be seen. subwavefront. The two sub-wavefronts colliding with each other in this way will cause the lens to form a bonding line C as shown in FIG. 4 after the lens is manufactured. The joint line C has extended into the refractive portion 110' of the lens, thus affecting the optical quality of the lens.

In contrast, as shown in FIG. 5, since the lens 100 of this embodiment (ie, the lens 100 of FIGS. 1A to 1C) has a depression 210 at the edge portion 200, that is, a boss 322 is provided on the mold 300, the boss 322 has a blocking effect, so it can slow down the flow velocity of the material at the edge of the cavity 330 , so that the flow velocity of the material at the center of the cavity 330 is relatively consistent with that at the edge of the cavity 330 . From the wave fronts F1' to F4', it can be seen that since the flow velocity of the material at the edge of the mold cavity 330 is relatively consistent with that in the center of the mold cavity 330, the collision of the two sub-wavefronts has been improved. Therefore, the lens 100 of this embodiment is manufactured , the chance of generating the bonding line C is low, thereby reducing the chance of generating the bonding line C at the refracting portion 110 , so the lens 100 has good optical quality.

As mentioned above, the function of the bosses 322 is to slow down the flow velocity of the material at the edge of the mold cavity 330 , and the shape, quantity and distribution of the bosses 322 will affect the effect of slowing down. For example, since the sides of the polygonal three-dimensional boss 322 have a turning relationship, the relief effect provided by it is better than that of the non-turning semi-spherical or elliptical-spherical boss.

In addition, the mold for injection molding usually has a movable side and a fixed side, and ejector pins/ejector pins or mold cores for assisting demoulding are mostly disposed on the movable side. Please refer to Fig. 1A to Fig. 1C and Fig. 2 again, in the present embodiment, the first mold 310 is positioned at the movable side, and the second mold 320 is positioned at the fixed side, that is to say, when demolding, the first mold 310 can eject the lens 100 through its mold core (not shown in the figure). However, when the mold is opened, the lens is occasionally fixed on the surface of the second mold 320 and cannot be separated, and the design of the draft slope on the boss 322 can make the mold release more smooth when the mold is opened.

More specifically, in this embodiment, each depression 210 has a proximal surface 214 facing away from and closer to the optical axis A, a centrifugal surface 212 facing and farther away from the optical axis A, and connecting the proximal surface 214 and the centrifugal surface. The bottom surface 216 of 212, wherein the proximal surface 214 is located between the optical axis A and the centrifugal surface 212, and both the proximal surface 214 and the centrifugal surface 212 are inclined relative to the bottom surface 216, and such a design is conducive to the mold release process during mold opening .

Moreover, in order to further improve the release ability of the lens, the angles of the proximal surface 214 and the centrifugal surface 212 relative to the bottom surface 216 are selectively different. In this embodiment, as shown in FIG. 1A , the first inclination angle θ1 of the centrifugal surface 212 relative to the bottom surface 216 in the material of the lens 100 is greater than the second inclination angle θ1 of the proximal surface 214 relative to the bottom surface 216 in the material of the lens 100 . Tilt angle θ2. When designing, in this embodiment, the ratio obtained by dividing the first inclination angle θ1 by the second inclination angle θ2 has a basic positive effect when it is 1.01 to 2, and its benefit is better when it is in the range of 1.05 to 1.3. And at 1.2-1.3, its benefit is the best. For example, in this example, the first inclination angle θ1 is, for example, 65 degrees, and the second inclination angle θ2 is, for example, 52 degrees, so the ratio thereof is about 1.25. In this example, the direction of the normal vector of the bottom surface 216 and the optical axis A are substantially horizontal.

In addition, it should be emphasized that the above-mentioned ratio of the inclination angle of the recess 210 is not limited to be greater than 1, it must also be less than 1, and it can also be set in reverse according to the ratio of opening up. In addition, in other embodiments, it is also possible that the first mold 310 is located on the fixed side, and the second mold 320 is located on the movable side.

In this embodiment, as shown in FIG. 1C , the distances R from the recesses 210 to the optical axis A are substantially the same. For example, the distances R from the centers of the recesses 210 to the optical axis A are substantially the same. In addition, in this embodiment, the line L connecting these depressions 210 and the optical axis A in the direction perpendicular to the optical axis A and the symmetry plane P divide the lens 100 into a plurality of fan-shaped regions Z with substantially equal angles, that is, The expansion angles φ of these fan-shaped regions Z are substantially equal to each other.

In this embodiment, the minimum thickness T3 of the edge portion 200 in the direction parallel to the optical axis A at each recess 210 is smaller than the thickness T2 of the diopter 110 on the optical axis A. In other words, the minimum distance H3 (as shown in FIG. 2 ) from the top of the boss 322 to the first mold 310 is slightly smaller than the thickness T2 of the diopter 110 on the optical axis A, so that the resistance of the material flow can be adjusted. . The above-mentioned difference in size between the two is, for example, within 30% of the thickness T2 of the optical diopter 110 on the optical axis A. And when the difference is 10 percent, the effect is better; and when the difference is 5 percent, the effect is the best.

In this embodiment, the ratio obtained by dividing the width W1 of each recess 210 in the radial direction perpendicular to the optical axis A by the width W2 of the edge portion 200 in the radial direction falls within a range of 0.7 to 0.99. In one embodiment, the ratio may fall within a range of 0.85 to 0.9. In this way, the above-mentioned design of the width W1 helps the mold 300 not interfere with the machining of the tool during machining.

In addition, in an injection molding simulation, regarding the volume shrinkage distribution after injection molding is completed, compared with the lens in FIG. There is less difference in volume shrinkage on opposite sides of the gate. In addition, compared with the lens of FIG. 3 without the recess 210 as shown in FIG. 1A , the difference in shrinkage ratio of each part of the lens 100 of this embodiment is smaller. Therefore, the error amount and uniformity of the surface shape of the lens 100 of this embodiment are better.

To sum up, in the lens of the embodiment of the present invention, the diopter has a negative diopter, the ratio of the maximum thickness ratio of the lens in the direction parallel to the optical axis is greater than 2.5, and the edge of the lens surrounding the diopter Has multiple depressions. In this way, when the lens is produced by the injection molding process, the convex land on the mold that is complementary to the concave shape of the lens can block the flow rate of the fluid, so that the fluid injected into the mold cavity corresponds to the thicker edge in the mold cavity The flow velocity in the region of the refraction portion is not too much greater than the flow velocity in the region of the mold cavity corresponding to the thinner refractive portion. In this way, when the fluid is injected from the gate into the mold cavity, the wavefront of the fluid can reach the opposite side of the gate more evenly, and will not collide before reaching the opposite side of the gate, thereby reducing the loss of the lens There is a chance of combining lines in the refractive department. Since the refractive portion of the lens of the embodiment of the present invention may not have a joint line, the lens has good optical quality.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Anyone skilled in the art can still design the lens, such as the protrusion, without departing from the spirit and scope of the present invention. The shape and layout, etc., are modified or changed, and the scope of protection of the present invention is still subject to the claims.

Claims (10)

1. A kind of 1. lens, it is characterised in that including：

   Dioptric portion, there is negative diopter；And

   Edge part, around the dioptric portion, and outside effective dioptric area of the lens, the edge part has multiple recessed Falling into, the multiple depression is set relative to the plane of symmetry for specular, and the plane of symmetry includes the optical axis of the lens, wherein Maximum thickness of the lens on the direction parallel to the optical axis than ratio be more than 2.5.
2. 2. lens according to claim 1, it is characterised in that each depression is recessed for polyhedron, the polyhedron depression At least two adjacent planes between there is chamfering.
3. 3. lens according to claim 1, it is characterised in that the maximum thickness ratio is the lens parallel to described The ratio of thickness described in maximum gauge divided by the lens on the direction of optical axis on optical axis.
4. 4. lens according to claim 2, it is characterised in that each depression has close to the nearly heart face of the optical axis, far The bottom surface in nearly heart face described from the centrifugation face in the direction of the optical axis and connection and the centrifugation face, the nearly heart face is positioned at described Between optical axis and the centrifugation face, and the centrifugation face and the nearly heart face are all relative to the inclined bottom surface.
5. 5. lens according to claim 4, it is characterised in that the centrifugation face is relative to the bottom surface in the lens The first inclination angle in material is more than nearly second inclination angle of the heart face relative to the bottom surface in the material of the lens.
6. 6. lens according to claim 5, it is characterised in that obtained by first inclination angle divided by second inclination angle To ratio be to fall in the range of 1.05 to 1.3.
7. 7. lens according to claim 1, it is characterised in that the multiple distance for being recessed to optical axis phase each other Together.
8. 8. lens according to claim 1, it is characterised in that the multiple depression is with the optical axis perpendicular to the light The lens are divided into multiple equal angular sector regions by line and the plane of symmetry on the direction of axle.
9. 9. lens according to claim 1, it is characterised in that the edge part is in each recess parallel to the light Minimum thickness on the direction of axle is less than thickness of the dioptric portion on the optical axis.
10. 10. lens according to claim 1, it is characterised in that each depression perpendicular to the optical axis radially The ratio of width divided by the edge part obtained by the width radially is fallen in the range of 0.7 to 0.99.