Assembly method of glass-plastic hybrid all-metal lens

Abstract

The present invention discloses a glass-plastic hybrid all-metal lens, belonging to the field of optical imaging technology, and provides a one-end assembled glass-plastic hybrid all-metal lens, comprising a lens barrel, wherein a first glass lens, a first plastic lens, a second glass lens, and a second plastic lens are sequentially arranged in the lens barrel from top to bottom, a first spacer is arranged between the first plastic lens and the second glass lens; a second spacer is arranged between the second glass lens and the first plastic lens; fitting gaps are provided between the first glass lens, the second glass lens, the first plastic lens, and the second plastic lens and the inner circumferential wall of the lens barrel; the present invention also provides an assembling method of the lens; the design of the present invention effectively improves the problem of high and low temperature defocusing caused by different expansion coefficients of glass, plastic, metal, etc., and has high commercial value and promotion value.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and more particularly to an assembling method of a glass-plastic hybrid all-metal lens. Background Art

[0002] With the rapid development of science and technology, the usage rate of optical lenses has gradually increased, and people's requirements for optical lenses have become higher and higher.

[0003] To ensure a wide field of view, most surround-view lenses currently utilize a hybrid glass-plastic optical architecture. However, due to the different expansion coefficients of glass, plastic, and metal, this architecture often leads to numerous issues during reliability testing. These include lens defocus within high temperature ranges, film cracking of plastic lenses, whitening of ink-coated glass lenses, and chipping of glass lenses. Furthermore, these issues fail to meet the required wide field of view image plane, and fogging dissipates quickly. Defocus is maintained within the temperature range of -40°C to 105°C, and focusing performance varies significantly with temperature. Due to the all-metal exterior structure, reliability cannot be guaranteed over time, and the cost of the lens itself is high. During optical design, to mitigate temperature drift in the optical system, lens optimization often takes a long time. While theoretical values ​​often meet the requirements, defocus and peripheral blurring may still occur during actual production. To mitigate internal lens expansion, most utilize a two-head assembly method, increasing manufacturing costs and production cycles. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a glass-plastic hybrid all-metal lens to overcome the current problem of high and low temperature defocus caused by the different expansion coefficients of glass, plastic, and metal, as well as the problem of plastic lens film cracking and glass lens whitening and chipping during reliability testing.

[0005] In order to solve the above problems, the present invention provides a glass-plastic hybrid all-metal lens, including a lens barrel and a pressure ring. The lens barrel is provided with a first glass lens, a first plastic lens, a second glass lens and a second plastic lens from top to bottom. The pressure ring is arranged on the lens barrel and presses the first glass lens. A first spacer is arranged between the first plastic lens and the second glass lens; a second spacer is arranged between the second glass lens and the first plastic lens; and a fitting gap is provided between the first glass lens, the second glass lens, the first plastic lens and the second plastic lens and the inner circumferential wall of the lens barrel.

[0006] The glass-plastic all-metal lens of the present invention has the following technical advantages:

[0007] When designing the structure of the glass-plastic lens of the present invention, a fitting gap is designed for the fit between the lens barrel and the lens, so that the imaging effect of the glass-plastic hybrid all-metal lens is less affected by high temperature at high temperatures, and the first glass lens, the first plastic lens, the second glass lens, and the second plastic lens are separated by the first spacer and the second spacer to prevent the problem of high and low temperature defocus caused by the internal heat expansion of the lens, as well as the problem of plastic lens film cracking and glass lens ink whitening and chipping during the reliability test.

[0008] As a preferred solution, the first glass lens is fixed to the lens barrel via a pressure ring on the outside, and the first glass lens is provided with a first inclined surface, and the pressure ring is provided with a second inclined surface, the first inclined surface is in contact with the second inclined surface and there is an angle between them; the glass-plastic hybrid all-metal lens of the present invention has an angle-differentiated design in the fixed position between the pressure ring and the first glass lens. In the current existing structure, the pressure position between the pressure ring and the first glass lens is designed with the same angle. When the first glass lens and the pressure ring are at the same height, this design cannot release more space to meet the vertical expansion needs of the lens. Therefore, this design has a differentiated design here, and an angle is set between the first glass lens and the pressure ring. The angle can be adjusted according to different lenses. Such an angle-differentiated design ensures that when the lens is at high temperature, the pressure ring leaves a part of the expansion space inside the lens barrel. Combined with the above-mentioned fitting gap design, the overall anti-expansion performance of the lens is better.

[0009] As a preferred solution, the material of the pressure ring is zinc, and the expansion coefficient of the pressure ring is 36.0*E-6 / °C.

[0010] As a preferred solution, the angle is 1°-10°.

[0011] As a preferred solution, the first spacer and the second spacer are both made of Invar, and the expansion coefficients of the first spacer and the second spacer are both 1.3912*E-6 / °C; the lens barrel is made of aluminum, and the expansion coefficient of the lens barrel is 23.8*E-6 / °C; when designing the glass-plastic lens structure of the present invention, in order to reduce the expansion height of the lens barrel components, Invar with a smaller expansion coefficient is used when selecting the material of the spacers between the lenses. This material has a lower thermal expansion coefficient; the pressure ring needs to ensure that it can release a larger amount of expansion at high temperatures to minimize the vertical extrusion of all components inside the lens barrel, so zinc, a metal material with a larger expansion coefficient, is selected.

[0012] As a preferred solution, the pressure ring is connected to the lens barrel via a threaded connection, and the threaded connection is a multi-start thread. The connection thread between the pressure ring and the lens barrel of the present invention is designed. Currently, some connections on the market are single-start threaded connections, which cannot solve the expansion problem inside the lens barrel. The present invention replaces the single-start thread with a multi-start thread. The lead of the multi-start thread is larger. The lead of the double-start thread with the same pitch is many times that of the single-start thread, and the self-locking ability is slightly reduced. The force perpendicular to the normal direction of the thread and acting on the surface of the thread is decomposed into axial and radial components. The multi-start thread is less subjected to axial force, so the multi-start thread design is adopted.

[0013] As a preferred solution, the size of the fitting gap is 0.003-0.012 mm.

[0014] Another technical problem to be solved by the present invention is: the present invention provides an assembly method of the glass-plastic hybrid all-metal lens to solve the problem that the current lens assembly requires multiple heads and is complicated to assemble.

[0015] The assembly method of the present invention comprises the following steps:

[0016] 1) Preparation of component materials: Prepare the lens barrel, first glass lens, first plastic lens, second glass lens, second plastic lens, first spacer, and second spacer, and bake and cool the above materials;

[0017] 2) installing the first glass lens, the first plastic lens, the second glass lens, the second plastic lens, the first spacer, and the second spacer after being cooled in step 1) onto the lens barrel;

[0018] 3) Pre-lock the pressure ring onto the lens barrel processed in step 2) by threading, leaving a certain thread gap;

[0019] 4) baking the lens barrel treated in step 3) again, and locking the pressure ring and the lens barrel after baking;

[0020] 5) After the lens barrel cools down, perform glue application between the pressure ring and the lens barrel to complete the assembly.

[0021] As a preferred solution, the baking conditions in step 1) and step 4) are: baking at 100°C-110°C for two hours, and the cooling conditions in step 1) and step 5) are: cooling at room temperature for 2 hours.

[0022] As a preferred solution, in step 4), the pressure ring and the lens barrel are locked by a locking machine, and the locking time is less than 40 seconds.

[0023] The glass-plastic all-metal lens assembly method of the present invention has the following advantages:

[0024] 1. The locking of the pressure ring and the lens barrel structure currently on the market is performed at room temperature. As a result, when the temperature is high, the internal lens and the spacer are heated, expanded, squeezed and deformed. The method of the present invention is to bake all the components at high temperature to remove the internal stress of the components when assembling the lens. After cooling, the components are assembled. After the assembly is completed, the pressure ring is pre-locked first, and the assembled lens is placed in the oven for baking again. While the lens is still in a high temperature state, the lens is immediately placed in the locking machine to lock the pressure ring, and the baking time of the lens is reasonably controlled to achieve better imaging effects.

[0025] 2. Due to the full optimization and improvement in the locking and assembly steps, the structure of the present invention adopts a one-head assembly method. All lenses are installed through the lens barrel from the side of the pressure ring, and finally the pressure ring is covered to complete the assembly, which saves the production cost of the lens barrel and improves production efficiency. It saves assembly time in the entire lens production process, improves work efficiency, and shortens the production cycle. The integrated assembly also saves productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the front structure of Example 1 of the present invention;

[0027] Figure 2 Schematic diagram of the fitting clearance structure of Example 1 of the present invention;

[0028] Figure 3 Schematic diagram of the angle structure of Example 1 of the present invention;

[0029] Figure 4-6 This is the MTF test chart of the product in the embodiment of the present invention at 25°C;

[0030] Figure 7-9 This is the MTF test chart of the product in the embodiment of the present invention at 105°C;

[0031] Description of the numbers in the figure:

[0032] Among them: 1. First glass lens; 2. First plastic lens; 3. First spacer; 4. Second glass lens; 5. Second spacer; 6. Second plastic lens; 7. Lens barrel; 8. Pressing ring; 9. Fitting clearance; 10. Angle. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] The glass-plastic hybrid all-metal lens of the present invention has undergone many reliability tests, and ANSYS software has been used to perform simulation verification under different conditions. It was found that the ultimate cause is that glass, plastic and metal are different materials in high and low temperature environments, and they have different expansion coefficients, which causes the plastic lens to be squeezed and deformed after being subjected to high temperature, and the plastic lens to produce film cracks. Due to the extrusion and deformation of the plastic, the surface shape of the aspheric surface in the plastic lens changes, resulting in defocus at high and low temperatures. At high temperatures, since the outer structure of the lens barrel is made of metal material, its expansion coefficient is smaller than that of the plastic lens. When the plastic lens expands, the lens is always in a compressed state. Due to the thermal expansion, the ink on the glass lens is completely stuck and bonded to the plastic lens. When the high temperature turns to low temperature, the plastic lens shrinks back. This repeated process causes the ink coating strength on the glass lens to weaken, causing the ink layer on the glass to fall off and adhere to the plastic lens. From the appearance, it can be seen that the lens is whitening. During the initial optical design phase, detailed simulations were conducted to verify the sensitivity of plastic lenses. This approach minimized the impact of changes in the plastic lens's surface profile on the lens' back focus at high temperatures. This is because the fit between the lens and the lens barrel directly impacts the lens's production yield. High temperatures also create a need for clearance between the lens and the lens barrel, creating a conflicting situation. Therefore, when designing lens tolerances, the present invention minimized the decentering tolerance, ensuring that the hybrid glass-plastic lens maintains its yield even with clearance between the lens barrel and the lens.

[0035] From a structural design perspective, in a conventional lens assembly, the glass lens is the first element, with the plastic lens below it. The plastic lens rests directly on the metal lens barrel, and the internal air gap ring is made of metal. The thermal expansion coefficients of the three materials are as follows: aluminum (using the aluminum in the lens barrel as an example): 23.8*E-6 / °C; glass (glass lens):

[0036] 6.0*E-6 / ℃; Plastic (plastic lenses): 70*E-6 / ℃.

[0037] The above expansion coefficients show that plastic lenses have a greater expansion coefficient than metal and glass. The following theoretical calculation, based on a 10mm length, uses the formula: (length) * (temperature) * (expansion coefficient). The typical temperature range is from 25°C (normal) to 105°C (high). As can be seen, when the component's temperature rises from 25°C to 105°C, the linear expansion of the metal is 0.02023mm, the linear expansion of the glass is 0.0051mm, and the linear expansion of the plastic is 0.0595mm. These calculations indicate that improperly controlling the component assembly structure can significantly impact the lens's high and low temperature performance and reliability.

[0038] From an assembly structural perspective, all internal components rest on a supporting surface within the lens barrel. A pressure ring presses all internal components (including lenses and spacers), and a threaded connection is used between the pressure ring and the lens barrel. At high temperatures, all internal components are heated and expand. Because the supporting surface of the lens barrel is fixed and cannot move, this causes the overall height to shift toward the pressure ring. The pressure ring, which is threaded and connected to the lens barrel, cannot move at high temperatures. This severely squeezes the internal components of the lens barrel, especially plastic lenses, which are subject to significant stress, affecting the lens's surface shape. When assembled at room temperature, the plastic parts inside the lens barrel have an interference fit of 0.005mm per side with the inner diameter of the lens barrel. At high temperatures, the outer diameter of the plastic parts will also squeeze against the inner diameter of the lens barrel.

[0039] Example 1

[0040] like Figure 1-Figure 3 As shown, Figure 1 This is a schematic diagram of the front structure of this embodiment, which can be seen from Figure 1 As can be seen from the figure, the lens of this embodiment includes a first glass lens 1, a first plastic lens 2, a second glass lens 4, and a second plastic lens 6, which are arranged in sequence from top to bottom inside the lens barrel 7, and a first spacer 3 is provided between the first plastic lens 2 and the second glass lens 4, and a second spacer 5 is provided between the second glass lens 4 and the second plastic lens 6; the outside of the first glass lens 1 is connected and fixed to the lens barrel 7 through a pressure ring 8. Specifically, the pressure ring 8 is connected to the upper end of the lens barrel 7, and the bottom of the pressure ring 8 is pressed tightly against the upper part of the first glass lens 1, thereby completing the fixation of the entire lens, thereby completing the one-head assembly of the glass-plastic hybrid all-metal lens of this embodiment, and better fixing all the lenses inside the lens barrel 7. A step is provided at the bottom of the lens barrel 7 for securing the second plastic lens 6. When the pressure ring 8 is tightened, the second plastic lens 6 is secured by the step and the second spacer 5. The second glass lens 4 is secured to the second spacer 5 via the first spacer 3. One end of the first plastic lens 2 contacts the first spacer 3, and the other end contacts the first glass lens 1. The upper portion of the first glass lens 1 is secured by the pressure ring 8, thereby completing a one-end assembly and securing the entire lens.

[0041] like Figure 2 As shown, Figure 2 Schematic diagram of the structure of the fitting gap 9 of the present invention. The first glass lens 1, the first plastic lens 2, the second glass lens 4, and the second plastic lens 6 of the present invention are all provided with the same fitting gap 9 between both sides and the inner wall of the lens barrel 7; Figure 3 As shown, Figure 3This is a schematic diagram of the angle 10 structure of the present invention. An angle 10 is set on the contact surface between the first glass lens 1 and the pressure ring 8. Specifically, the contact surface between the first glass lens 1 and the pressure ring 8 is a first inclined surface 1a, and the contact surface between the pressure ring 8 and the first glass lens 1 is a second inclined surface 8a. There is an angle 10 between the two inclined surfaces.

[0042] In this embodiment, the first glass lens 1 is designed with a bevel at the contact portion with the pressure ring 8, and the angle is 45° (compared to the lens barrel wall). The angle of the pressing position of the pressure ring 8 (and the base portion of the first glass lens 1) is designed to be 35° (compared to the lens barrel wall). There is an angle difference between the two, that is, the included angle 10, which is 10° in this embodiment. In other embodiments, the angle can also be adjusted according to different lenses (specific range is 1-10°). Such an angle differentiation design ensures that when the lens is at high temperature, the pressure ring 8 leaves a part of the expansion space inside the lens barrel 7.

[0043] Example 2

[0044] The structure of Example 2 is similar to that of Example 1, except that, in Example 2, the pressure ring 8 is a zinc material pressure ring 8, and the expansion coefficient of the zinc material pressure ring 8 is 36.0*E-6 / °C; the first spacer 3 and the second spacer 5 are Invar material spacers, and the expansion coefficient is 1.3912*E-6 / °C; the lens barrel 7 is an aluminum lens barrel 7, and the expansion coefficient is 23.8*E-6 / °C.

[0045] In Example 2, the pressure ring 8 is connected to the lens barrel 7 by a thread, and the thread is a multi-start thread. Generally, a 2-start or 3-start thread can be selected according to actual needs to strengthen the fixation. After the pressure ring 8 is threadedly connected to the lens barrel 7, it is also strengthened by gluing.

[0046] Example 3

[0047] This embodiment provides a method for assembling a glass-plastic hybrid all-metal lens, comprising the following steps:

[0048] 1) Prepare the components and materials: prepare the lens barrel 7, the first glass lens 1, the first plastic lens 2, the second glass lens 4, the second plastic lens 6, the first spacer 3, and the second spacer 5. Bake them at 100-110°C for two hours and cool them at room temperature for two hours.

[0049] 2) Installing the baked and cooled first glass lens 1, first plastic lens 2, second glass lens 4, second plastic lens 6, first spacer 3, and second spacer 5 onto the lens barrel 7;

[0050] 3) Pre-lock the pressure ring 8 onto the lens barrel 7 processed in step 2) by threading, leaving a certain thread gap (usually 1-3 threads, preferably 1 circle);

[0051] 4) baking the lens after the pre-locking treatment in step 3) at 100-110° C. for two hours. After the baking, directly locking the pressing ring 8 and the lens barrel 7 with a locking machine to obtain a lens locked with the pressing ring 8, and controlling the locking time to be less than 40 seconds;

[0052] 5) After the lens treated in step 4) is cooled at room temperature for 2 hours, glue is applied between the pressure ring 8 and the lens barrel 7 to complete the assembly.

[0053] In this embodiment, the outer diameters of the first and second plastic lenses 2, 6 are 10 mm. During actual testing, the squeeze between the two plastic lenses and the lens barrel 7 during baking in step 4) was controlled to be 0.005 mm per side. After two hours of baking in step 4), the outer diameter of the lens barrel 7 was 10.02023 mm. Actual measurements revealed that during high-temperature baking, the squeeze between the lenses was 0.03927 mm on both sides. Therefore, during structural design, the diameter of the lens barrel 7 was designed to be 10.03 mm. This ensures that the squeeze between the lenses and the lens barrel 7 remains within 0.005 mm when the lens is heated.

[0054] Under different outer diameters, different fitting clearances 9 can also be designed according to different situations. When the outer diameter of the plastic lens is 7.5mm, the outer diameter of the lens barrel 7 needs to be designed to be 7.525mm. After high-temperature baking, the diameter of the plastic lens is 7.535mm, and the diameter of the lens barrel 7 is 7.545mm. The extrusion amount on one side is 0.005mm.

[0055] When the outer diameter of the plastic lens is 5.0mm, the outer diameter of the lens barrel 7 needs to be designed to be 5.01mm. After high-temperature baking, the diameter of the plastic lens is 5.021mm, the diameter of the lens barrel 7 is 5.03mm, and the extrusion amount on one side is 0.0045mm.

[0056] In the actual design of the fitting clearance 9, the unilateral fitting clearance 9 is generally controlled at 0.003-0.012 mm. When the outer diameter of the lens barrel 7 is small, the relative expansion amount is also small, so the design margin of the lens barrel 7 is also small during design. On the contrary, when the outer diameter of the lens barrel 7 is large, the relative expansion amount is large, so a relatively larger outer diameter is generally designed during design.

[0057] Determination of MTF value of assembled lens at high and low temperature:

[0058] The MTF test was carried out at normal (25℃) and high temperature (105℃) conditions, as shown in the following example: Figure 4-Figure 6 , Figure 7-Figure 9As shown in the MTF test chart, the MTF side view Figure 1 For comparison, Figure 6 as well as Figure 9 In the example, the corresponding unified curves have the same initial ordinates; Figure 5 as well as Figure 8 When the final horizontal axis is 60.0, the two curves correspond exactly. The figure also shows that the MTF test results of the present invention fluctuate little at high and low temperatures. This further verifies that the design of the present invention, including the lens combination, the design of the clearance 9, and the angle 10, has successfully solved the problem of lens performance degradation caused by high temperatures. In the reliability process, the lenses of the present invention have performed well.

[0059] The above description is based on the preferred embodiments of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be varied. All variations made within the scope of protection of the independent claims of the present invention are within the scope of protection of the present invention.

Claims

1. A method for assembling a glass-plastic hybrid all-metal lens, characterized in that: The glass-plastic hybrid all-metal lens comprises a lens barrel (7) and a pressure ring (8). The glass-plastic hybrid all-metal lens is assembled in a one-head style. The lens barrel (7) is provided with a first glass lens (1), a first plastic lens (2), a second glass lens (4) and a second plastic lens (6) in sequence from top to bottom. The pressure ring (8) is provided on the lens barrel (7) and presses the first glass lens (1). A first spacer (3) is provided between the first plastic lens (2) and the second glass lens (4). A second spacer (5) is provided between the second glass lens (4) and the first plastic lens (2). Fitting gaps (9) are provided between the first glass lens (1), the second glass lens (4), the first plastic lens (2) and the second plastic lens (6) and the inner peripheral wall of the lens barrel. The assembly method of the glass-plastic hybrid all-metal lens comprises the following steps: 1) Preparation of component materials: prepare the lens barrel (7), the first glass lens (1), the first plastic lens (2), the second glass lens (4), the second plastic lens (6), the first spacer (3) and the second spacer (5), and bake and cool the above materials; 2) installing the first glass lens (1), the first plastic lens (2), the second glass lens (4), the second plastic lens (6), the first spacer (3), and the second spacer (5) cooled in step 1) onto the lens barrel (7); 3) Pre-locking the pressure ring (8) onto the lens barrel (7) processed in step 2) through threaded connection, leaving a certain thread gap; 4) baking the lens barrel (7) processed in step 3) again, and directly locking the pressure ring (8) and the lens barrel (7) after baking; 5) After the lens barrel (7) cools down, glue is applied between the pressure ring (8) and the lens barrel (7) to complete the assembly.

2. The method for assembling the glass-plastic hybrid all-metal lens according to claim 1, characterized in that: The baking conditions in step 1) and step 4) are: baking at 100° C.-110° C. for two hours, and the cooling conditions in step 1) and step 5) are: cooling at room temperature for 2 hours.

3. The method for assembling the glass-plastic hybrid all-metal lens according to claim 1, characterized in that: In step 4), the pressing ring (8) and the lens barrel (7) are locked by a locking machine, and the locking time is less than 40 seconds.

4. The method for assembling a glass-plastic hybrid all-metal lens according to claim 1, characterized in that: The size of the fitting gap (9) is 0.003-0.012 mm.

5. The method for assembling a glass-plastic hybrid all-metal lens according to claim 1, characterized in that: The first glass lens (1) is provided with a first inclined surface (1a), the pressure ring (8) is provided with a second inclined surface (8a), and the first inclined surface (1a) and the second inclined surface (8a) are in contact with each other and have an included angle (10).

6. The method for assembling a glass-plastic hybrid all-metal lens according to claim 5, characterized in that: The angle (10) is 1°-10°.

7. The method for assembling a glass-plastic hybrid all-metal lens according to claim 1, characterized in that: The material of the pressure ring (8) is zinc, and the expansion coefficient of the pressure ring (8) is 36.0*E-6 / °C.

8. The method for assembling a glass-plastic hybrid all-metal lens according to claim 7, characterized in that: The material of the first spacer (3) and the second spacer (5) are both Invar steel, and the expansion coefficients of the first spacer (3) and the second spacer (5) are both 1.3912*E-6 / °C; the material of the lens barrel (7) is aluminum, and the expansion coefficient of the lens barrel (7) is 23.8*E-6 / °C.

9. The method for assembling a glass-plastic hybrid all-metal lens according to claim 1, characterized in that: The pressure ring (8) and the lens barrel (7) are connected via multiple threads.

Images