TWI837745B - Laser welding method for combining lenses and lens set - Google Patents

Abstract

A laser welding method for combining lenses, comprising: placing a first lens on a second lens, so that a first peripheral edge of the first lens and a second peripheral edge of the second lens are in contact with each other and form an interface ring a slit; a laser is emitted along an annular track on the first lens adjacent to the first peripheral edge, so that a material located in the annular track is melted, wherein the annular track is along the distance between the first lens and the second lens The projection of the contact direction is the same as the projection of the first peripheral edge along the contact direction; when the material flows down and covers the interface annular slit, stop the laser; and wait for a predetermined time after stopping the laser The cooling time allows the material to form multiple fusion bonds.

Description

Lens laser bonding method and lens assembly

The present invention relates to a lens bonding method, and in particular to a lens laser bonding method.

At present, car lenses have been gradually used in a large number of devices on cars, such as reversing displays, driving recorders or self-driving cars. The primary consideration for car lenses is safety and durability, so the general lens material is glass, because it can withstand higher temperatures and is not easy to deform than plastic, and the lens material is mostly metal aluminum, because aluminum can withstand greater pressure and higher temperatures than plastic. At present, most car lenses first lock the upper cover on the lens shaft and then apply UV glue to fix it. The combined fixing method uses UV glue to fix it without loosening. The upper and lower lens barrels need to be screwed and processed, which is also more troublesome. After locking, the upper cover will also have a slight tilt instead of being evenly downward.

In view of the above, the present invention provides a lens laser bonding method and a lens assembly.

According to an embodiment of the present invention, a lens laser bonding method comprises: placing a first lens on a second lens so that a first periphery of the first lens and a second periphery of the second lens contact each other and form an intervening annular slit; emitting a laser along an annular track adjacent to the first periphery on the first lens so that the material located at the annular track melts, wherein the projection of the annular track along the contact direction of the first lens and the second lens is the same as the projection of the first periphery along the contact direction; stopping the laser when the material flows downward and covers the intervening annular slit; and waiting for a predetermined cooling time after stopping the laser so that the material forms a plurality of molten bonding parts.

According to an embodiment of the present invention, a lens assembly includes a first lens, a second lens, and a plurality of fusion bonding portions. The second lens is connected to the first lens, wherein an intervening annular slit is provided between the first lens and the second lens. The fusion bonding portion is located in the intervening annular slit and is adjacent to the outer peripheral side walls of the first lens and the second lens.

Through the above structure, the lens laser bonding method disclosed in this case is to place two lenses up and down, and shoot the laser to the annular track near the seam to melt the material, so that when the molten material flows and covers the seam, the material will form multiple molten bonding parts after a predetermined cooling time. In this way, the two lenses will be able to form a lens assembly that is more stable than the lens assembly bonded with glue. The lens assembly disclosed in this case does not use the adhesion of external materials such as glue, but uses the melting-solidification reshaping method of the lens material itself, so that the strength of the entire lens assembly at the joint can be close to the strength of the lens itself, thereby effectively improving the safety and durability of the lens, and also reducing the deviation and misalignment between the two lenses caused by collision or vibration during use of the lens assembly.

The above description of the disclosed content and the following description of the implementation method are used to demonstrate and explain the spirit and principle of the present invention, and provide a further explanation of the scope of the patent application of the present invention.

S1~S7: Steps

1: Lens set

10: First shot

101: First Week

103: Circular track

12: Second shot

121: Second week

123: Peripheral wall

14: Interconnecting annular slits

16: Melt bonding section

18: Mirror axis

3: Laser

FIG1 is a schematic cross-sectional view of a lens assembly according to an embodiment of the present invention.

Figure 2 is a flow chart of a lens laser bonding method according to an embodiment of the present invention.

FIG3 is another flow chart of a portion of the lens laser bonding method according to an embodiment of the present invention.

FIG4 is a schematic cross-sectional diagram of a state of the laser bonding process of a lens assembly according to an embodiment of the present invention.

FIG5 is a cross-sectional schematic diagram of another state of the laser bonding process of the lens assembly according to an embodiment of the present invention.

The detailed features and advantages of the present invention are described in detail in the following implementation method. The content is sufficient for anyone familiar with the relevant technology to understand the technical content of the present invention and implement it accordingly. According to the content disclosed in this specification, the scope of the patent application and the drawings, anyone familiar with the relevant technology can easily understand the relevant purposes and advantages of the present invention. The following embodiments are to further illustrate the viewpoints of the present invention, but do not limit the scope of the present invention by any viewpoint.

The lens assembly and lens laser bonding method mentioned in the embodiments of the present invention can be applied to various lenses such as cameras, video recorders, dashcams, mobile phones or computers, etc. The laser used can be a pulse laser or a continuous wave laser (CW laser), and the wavelength can include infrared light, visible light, ultraviolet light or other electromagnetic waves of other bands sufficient to heat and melt the lens material in this invention. In this invention, two lenses are defined as the first lens and the second lens respectively, and the first lens is placed on the second lens during the bonding process. In addition, there is no limitation on any relationship between the two lenses. Therefore, as long as two lenses can be bonded to produce a lens assembly using the bonding method of this invention, they can become the first and second lenses described in this invention, and this part should not be a limitation of this invention. On the other hand, for the lens laser bonding method and lens assembly with more than three lenses, if the process is based on the lenses bonding two by two to each other, it can be based on the claims of this case and therefore falls within the scope of protection of this case.

Please refer to FIG. 1, which is a schematic diagram of a lens assembly according to an embodiment of the present invention. As shown in FIG. 1, the lens assembly 1 includes a first lens 10 located at the top, a second lens 12 located at the bottom, and a plurality of fusion bonding portions 16 between the two lenses, wherein the two lenses each have a lens and a lens barrel, in particular a lens made of glass and a lens barrel made of metal, and although this example shows that the first lens 10 has a shorter lens barrel than the second lens 12, the implementation of the two lenses is not limited to the examples given herein. In this figure, the lens assembly 1 is a combination of a first lens 10 and a second lens 12. From the cross-sectional view, it can be seen that the first lens 10 is connected to the second lens 12, wherein there is an intervening annular slit 14 between the first lens 10 and the second lens 12. The fusion bond 16 is located in the intervening annular slit 14 and is adjacent to the outer peripheral side wall 123 of the first lens and the second lens. Specifically, the intervening annular slit 14 is formed at the junction of the lens barrels of the first lens 10 and the second lens 12, and the intervening annular slit 14 near the outer peripheral side wall 123 is covered by an annular closed fusion bond 16. Different from the previous technology, the material of the fused joint 16 is not a glue-like material such as UV glue, but is formed by solidification of molten metal such as aluminum alloy. At the same time, the fused joint 16 has a certain degree of penetration into the intermediate annular slit 14 in terms of structure. Therefore, the strength of the fused joint 16 material itself and the large area of contact make the fused joint 16 have a significant effect on the joining of the two lenses, and can effectively resist external force vibration, so that the lens set 1 can maintain the imaging quality for a long time, and is a reliable and durable lens set.

Specifically, the first lens 10 and the second lens 12 can be joined to form the lens set 1 by laser joining, especially by the lens laser joining method of the embodiment described below. Please refer to FIG. 2, which is a flow chart of the lens laser joining method according to an embodiment of the present invention. As shown in FIG2 , the lens laser bonding method includes step S1: placing the first lens on the second lens so that the first periphery of the first lens and the second periphery of the second lens contact each other and form an intermediate annular slit; step S3: emitting laser along the annular track adjacent to the first periphery on the first lens so that the material located at the annular track melts, wherein the projection of the annular track along the contact direction of the first lens and the second lens is the same as the projection of the first periphery along the contact direction; step S5: when the material flows downward and covers the intermediate annular slit, stopping the laser; step S7: waiting for a predetermined cooling time after stopping the laser so that the material forms a plurality of molten bonding parts.

Although the lens laser bonding method of this article clearly states that the first lens is above the second lens, the so-called above does not limit the placement in a manner perpendicular to the horizon. For example, in a specific embodiment, the first lens can be placed on the second lens in an inclined manner, so that due to the local slope change of the material, the heated and melted material can also naturally flow to the lower part to cover the junction of the two lenses. Therefore, it can fall within the scope of protection of this case according to the claims of this case.

In step S1, the first lens can be placed on the second lens so that the two lenses are in direct contact with each other, or the first lens can be temporarily suspended and fixed by a fixture, so that there is a space between the first lens and the second lens instead of direct contact. Similarly, in step S1, the first lens can be fixed on a reference plane first, and then the second lens is slowly approached from below the first lens, that is, this step can also be to place the second lens under the first lens. This simple change should not become a limiting condition of this case.

In addition, step S1 indicates that the first periphery and the second periphery can contact each other to form an intervening annular slit, however, other additional steps may be included before the two peripheries contact each other, which will be described later. In this example, the first periphery and the second periphery are annular planes, and the lens, the lens barrel and the lens may also be circular, but the area size and shape between the first periphery and the second periphery do not need to be completely equal, that is, the area of the first periphery may be larger than the area of the second periphery or the area of the second periphery may be larger than the area of the first periphery, so the first periphery and the second periphery only need to correspond to each other to produce contact and form an intervening annular slit.

In step S3, the laser heats the material along the annular track on the first lens near the first periphery. Specifically, the material in the annular track in this example is an aluminum alloy such as ADC12, which mainly includes aluminum, silicon, copper, iron and other substances, and has a melting point of about 550 degrees Celsius (because it is a mixture, there is no single accurate melting point). Aluminum is lighter than other metals and has a lower melting point, making it very suitable for welding using the laser processing method of this case. However, the lens laser processing method of this case is not limited to the case where the lens material is an aluminum alloy, and can also include other metals, for example; in addition, the first lens and the second lens can be made of different materials respectively, such as the first lens that needs laser processing uses aluminum, and the second lens uses steel, etc. Even the annular track portion of the first lens can use a material different from that of other parts of the first lens. The laser can be properly focused to increase the light intensity per unit area to melt the material. Specifically, the laser intensity used for welding can reach 1MW/ ^cm2 , and the focus size can be about 1mm. The laser intensity is related to the characteristics of the material to be welded. In practice, appropriate materials and laser-related parameters can be selected according to different needs, which will not be elaborated here.

When the material in the annular track on the first lens is heated by the laser and melted into liquid, the molten material will flow toward the second lens along the contact direction between the first lens and the second lens due to gravity, and the projection of the contact direction between the first lens and the second lens is the same as the projection of the first periphery along the contact direction, that is, the molten material will flow along the contact direction and in step S5, when the material flows downward and covers the intermediate annular slit formed by the two peripheries, the laser can be stopped.

Specifically, the above-mentioned stopping of the laser does not necessarily mean turning off the laser, but may be, for example, shifting the laser heating point or the laser focusing point. Specifically, when the material on the first heating point of the annular track has been heated and melted and flows to cover the above-mentioned interfacing annular slit, the laser and the lens group (the first lens and the second lens) can be relatively rotated, so that the laser heats different heating points on the annular track. For the hot spot, it is equivalent to producing the effect of stopping the laser. In addition, this case does not exclude the implementation of multi-process heating. For example, the lens axis of the lens group can be fixed to any direction in space, and the laser is fixed to a certain point on the above-mentioned annular circumference in space, so that when the method of this case proceeds to S5, the lens group begins to rotate with the lens axis as the rotation axis until the laser heats the above-mentioned first heating point again, which can be counted as one circle. Taking into account the differences in materials, laser characteristics and even the time the laser stays at the heating point, the operator can choose the optimized or required number of circles according to the method of this case, so that each heating point on the annular track is properly melted in each round of laser heating. More specifically, for multi-turn laser welding solutions, the laser can make fine adjustments to the mirror axis direction when heating each turn. That is, based on the circular trajectory of each turn, the controllable degree of freedom in the mirror axis direction can be increased to more accurately control laser welding and improve the quality of the molten bond.

In step S7, the molten material will reshape into a solid and form a molten bond after a period of time without receiving laser. Specifically, the molten material in the liquid state can completely cover, fill and slightly penetrate the interfacing annular interface through the plasticity of the liquid, so that a molten bond with a certain strength is formed at the junction between the two lens barrels after cooling. At this point, the lens laser bonding method of using laser bonding to form a lens set is completed.

Please refer to FIG. 3, which is another flow chart of a portion of the lens laser bonding method according to an embodiment of the present invention. In this embodiment, in addition to steps S1, S3, S5 and S7 shown in FIG. 2, a step S2 of adjusting the relative position of the first lens and the second lens is further included. As shown in FIG. 3, before step S3, that is, before emitting laser along the annular track, the relative position of the two lenses can be adjusted to adjust the optical properties of the lens set, that is, step S2: testing and optimizing the modulation transfer function (MTF) of the combination of the first lens and the second lens. In other embodiments, the optical transfer function (OTF) may also be tested and optimized. The relevant parameters and techniques are understandable to those with ordinary knowledge in this field and will not be elaborated here.

In step S2, adjusting the modulation transfer function can ensure the imaging quality of the lens set formed by the two lenses, which means that the two lenses still have some freedom for fine-tuning before welding. Specifically, whether the central axes (optical axes or lens axes) of the two lenses are parallel and coincident and whether the distance between the two lenses is appropriate will affect the imaging quality of the final lens set. Ideally, after ensuring the optimization of the MTF in step S2, the step S3 of using laser welding will no longer change the MTF; however, in other embodiments, the MTF can be fine-tuned again by using the slight plasticity of the molten material before forming a molten bond, that is, before step S7. Even in the case of the above-mentioned multi-circle welding example, the MTF can be fine-tuned after each circle of step S3 to ensure that the optical conditions of the lens assembly meet the expected standards. This multi-step fine-tuning method can help the MTF and improve the process yield.

Please refer to FIG. 4, which is a schematic diagram of a state of the laser bonding process of the lens set according to an embodiment of the present invention. As shown in FIG. 4, before laser welding, the first lens 10 can be placed on the second lens 12, and the modulation transfer function can be adjusted according to step S2 shown in FIG. 2, such as aligning the lens axes 18 of the two lenses, and preparing to make the first periphery 101 and the second periphery 121 correspond to each other to contact and form an intervening annular slit. Next, please refer to FIG. 5, which is another schematic diagram of the laser bonding process of the lens set according to an embodiment of the present invention. When the first periphery 101 of the first lens 10 and the second periphery 121 of the second lens 12 come into contact, an intervening annular slit 14 is generated. The laser 3 heats the annular track 103 of the first lens 10, which is made of aluminum alloy. After being heated and cooled by the laser 3, the molten material forms a molten bonding portion 16 on the outer peripheral side walls 123 of the two lenses to cover and fix the two lenses to form a lens assembly 1 as shown in FIG. 1 .

Although the lens assembly referred to in this case is a combination of a first lens and a second lens, as can be understood by a person skilled in the art, a general lens is composed of a lens barrel and a lens, so a single lens barrel or lens can be regarded as a part of a lens, or as a lens to be completed later. In another embodiment, the first lens is a lens barrel without a lens in part, and after the two lenses are in contact, an intervening annular slit close to the outer peripheral side wall is formed at the junction of the two lens barrels. That is, the intervening annular slit described in this case is not necessarily horizontal or vertical relative to the lens axis, as long as the molten material can cover the intervening annular slit to form a molten bonding portion after the lens laser bonding method of this case is performed.

Through the above structure, the lens laser bonding method and lens assembly disclosed in this case are to place two lenses up and down, and shoot the laser to the annular track near the joint to melt the material, so that when the molten material flows and covers the joint, the material forms multiple molten bonding parts after waiting for a period of time. In this way, the two lenses will be able to form a lens assembly that is more stable than a lens assembly bonded with glue. The lens assembly disclosed in this case does not use the adhesion of external materials such as glue, but uses the melting-solidification reshaping method of the lens material itself, so that the strength of the entire lens assembly at the joint can be close to the strength of the lens itself, thereby effectively improving the safety and durability of the lens, and also reducing the deviation and misalignment between the two lenses caused by collision or vibration during use of the lens assembly.

Although the present invention is disclosed as above by the aforementioned embodiments, it is not intended to limit the present invention. Any changes and modifications made within the spirit and scope of the present invention are within the scope of patent protection of the present invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

S1~S7: Steps

Claims (9)

A lens laser bonding method includes: placing a first lens on a second lens so that a first periphery of the first lens and a second periphery of the second lens contact each other and form an intervening annular slit; emitting a laser along an annular track on the first lens adjacent to the first periphery so that a material located on the annular track melts, wherein the projection of the annular track along the contact direction of the first lens and the second lens is the same as the projection of the first periphery along the contact direction; stopping the laser when the material flows downward and covers the intervening annular slit; and waiting for a predetermined cooling time after stopping the laser so that the material forms a plurality of molten bonding parts. The lens laser bonding method as described in claim 1 further comprises: emitting the laser along the annular track so that before the material located in the annular track melts, adjusting the relative positions of the first lens and the second lens to test and optimize a modulation transfer function of the combination of the first lens and the second lens. The lens laser bonding method as described in claim 1, wherein the material located in the annular track is an aluminum alloy. A lens assembly includes: a first lens; a second lens connected to the first lens, wherein the first lens and the second lens have an interfacing annular slit between them; and a plurality of fused bonding portions located in the interfacing annular slit and adjacent to an outer peripheral side wall of the first lens and the second lens, wherein the fused bonding portions are formed by a lens laser bonding method, the lens laser bonding method comprising: placing the first lens on the second lens so that a first periphery of the first lens and a second periphery of the second lens contact each other to form the interfacing annular slit. shaped slit; emitting a laser along an annular track on the first lens adjacent to the first periphery to melt a material located on the annular track, wherein the projection of the annular track along the contact direction between the first lens and the second lens is the same as the projection of the first periphery along the contact direction; before the material located on the annular track melts, adjusting the relative positions of the first lens and the second lens; when the material flows downward and covers the inter-connecting annular slit, stopping the laser; and waiting for a predetermined cooling time after stopping the laser to allow the material to form the molten bonding portions. The lens assembly as described in claim 4, wherein the lens laser bonding method further comprises: before emitting the laser along the annular track of the first periphery so that the material of the annular track melts, testing and optimizing a modulation transfer function of the combination of the first lens and the second lens. The lens assembly as described in claim 4, wherein the material located in the annular track is an aluminum alloy. The lens set as described in claim 4, wherein the first lens and the second lens each include a lens, and a material of the lens is glass. The lens set as described in claim 4, wherein the first lens and the second lens each include a lens barrel, a material of the lens barrel is metal, and the connecting annular slit is located between the lens barrel of the first lens and the lens barrel of the second lens. The lens assembly as described in claim 8, wherein the material of the lens barrel is an aluminum alloy.