JP2023148121A - Lens positioning structure - Google Patents

Abstract

To propose a lens unit with which it is possible to easily and precisely position lenses with respect to each other and suppress thermal deformation under high temperature.SOLUTION: Provided is a lens unit having resin lenses PL1 and PL2 on an upper face side SP1 and a lower face side SP2 of a hollow cylindrical positioning spacer SP, respectively. The lens unit is constructed such that the outer diameter parts of the upper face side SP1 and lower face side SP2 of the positioning spacer SP are approximately the same; a flange part on the outside of the beam passage diameter of the resin lenses PL1 and PL2 has vertical wall parts PL11, PL21 that are used for positioning with respect to the positioning spacer SP in the radial direction and straight parts PL12, PL22 that are used for positioning with respect to the positioning spacer SP in the optical axis direction; and the coefficient of linear expansion of the positioning spacer SP is smaller than those of the resin lenses PL1 and PL2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a lens positioning structure that suppresses deformation of a lens made of resin even under high temperatures.

The operating temperature of camera modules used in vehicles and surveillance applications has been rising, and in recent years, camera modules are required to operate in environments of 120 degrees or higher.

Most of the lenses used in camera modules that require operating temperatures of 120 degrees or higher are made of glass. Lenses made of glass have little change due to temperature and are difficult to deform even at high temperatures, but lenses made of resin deteriorate at high temperatures, resulting in decreased transmittance, changes in refractive index, and shape and dimensions due to thermal deformation. It is known that there are large changes.

In recent years, lens resins that suppress changes in transmittance and refractive index even under high temperatures have begun to be available on the market, and from the standpoint of productivity and cost, resin lenses are being used in camera modules for automotive and surveillance applications. It is beginning to be actively considered.

When using resin lenses, a lens positioning structure that can accommodate changes in performance due to temperature changes is required. In addition to suppressing changes in the angle of view and resolution due to changes in the refractive index and shape of the resin material due to temperature, the resin lens It is necessary to prevent thermal deformation of the material itself.

Patent Document 1 discloses a resin lens positioning structure that suppresses deterioration of optical performance due to temperature changes.

JP2021-12337

Patent Document 1 proposes a method of fixing a resin lens to a metal lens barrel, and by providing an appropriate clearance between the resin lens and each member that fixes the lens, it can be used in both low-temperature and high-temperature environments. It has a structure that prevents deformation.

The structure of Patent Document 1 proposes a structure that can suppress thermal deformation of a single resin lens, but many camera lenses use multiple lenses, and two resin lenses are used. It must be assumed that it will be used more than that. For this reason, the proposed structure is required for the number of resin lenses, making the lens unit structure complicated, which is disadvantageous in terms of accuracy and cost.

In particular, resin materials soften at high temperatures of 120 degrees or higher and become more deformable than at low temperatures or at room temperature, so a structure that is not subject to stress due to thermal expansion at high temperatures is required.

The present invention has been made to solve these problems, and even when a resin lens is used, there is little change in performance or performance deterioration depending on the usage environment, and it is possible to easily and precisely fix the lens position. The purpose is to provide a positioning spacer.

A lens unit having resin lenses on the upper and lower sides of a hollow cylindrical positioning spacer, wherein the outer diameters of the upper and lower sides of the positioning spacer are approximately the same diameter, and the resin lens has a light beam passing through the lens unit. The radially outer flange portion has a vertical wall portion used for positioning in the radial direction with the positioning spacer, and a straight portion used for positioning in the optical axis direction with the positioning spacer. A lens unit is provided that has a linear expansion coefficient smaller than that of the resin lens.

With this configuration, with a simple cylindrical positioning spacer, it is possible to precisely position the resin lens on the positioning spacer with the vertical wall part in the radial direction, and with the straight part in the optical axis direction. It may also be configured such that it can be precisely fixed to the positioning spacer via the spacer.

The cylindrical positioning spacer has approximately the same outer diameter on the upper and lower sides, and because of its simple structure, it can be used with parts such as cylindrical pipes, and is advantageous in terms of cost.

Further, since the resin lenses are simply inserted into the upper and lower surfaces of the positioning spacer, positioning can be performed easily.

Furthermore, with regard to thermal expansion at high temperatures, the vertical wall portion used for positioning the resin lens moves toward a larger diameter due to thermal expansion due to high temperatures. On the other hand, since the positioning spacer is formed of a material having a linear expansion coefficient smaller than that of the resin lens, its thermal expansion is smaller than that of the resin lens. Therefore, a space (clearance) is generated between the vertical wall portion of each resin lens and the positioning spacer. By intentionally creating this space, it is possible to prevent stress from being applied to the resin lens at high temperatures. As a result, lens deformation does not occur under high temperatures, so deterioration of optical performance can be suppressed.

Further, it is desirable that the positioning spacer is formed of a metal material having a coefficient of linear expansion of 30×E-6 or less.

By using a metal material with a small coefficient of linear expansion for the positioning spacer, it is possible to suppress changes in the lens spacing of the resin lens due to changes in the temperature of the usage environment, and it is possible to suppress changes in optical performance.

Furthermore, since the positioning spacer structure of the present application has a simple cylindrical structure, it can be used as a spacer by processing aluminum, stainless steel, etc. with high precision using an inexpensive process such as cylindrical grinding. Since the pipe can also be used as a positioning spacer, parts can be supplied in large quantities at low cost.

Alternatively, a chamfer may be formed on at least one of the upper and lower surfaces of the positioning spacer.

By forming the chamfer, it becomes easier to insert the resin lens into the positioning spacer.

Furthermore, a configuration may be adopted in which a continuous step shape is formed on the inner diameter portion of the positioning spacer.

Providing such continuous steps makes it difficult for reflected light generated at the inner diameter portion to enter the next lens. As a result, it is possible to suppress the occurrence of flare and ghost that degrade image quality.

The outer diameter part of the positioning spacer can be used to fix the positioning spacer to the inner diameter part of the holder.

Although the resin lens is positioned via a positioning spacer, it needs to be further fixed to another member such as a lens holder. Since the positioning spacer has a cylindrical outer diameter, it can be easily press-fitted into the inner diameter of the holder. Further, by setting the difference in linear expansion coefficient between the positioning spacer and the holder to 10×E-6 or less, it is possible to suppress misalignment due to thermal expansion in a high-temperature environment.

Positioning to the holder in the radial direction is done via a positioning spacer and not directly via the resin lens, so the resin lens is not subjected to stress due to thermal expansion at high temperatures.

According to the resin lens fixing structure using the positioning spacer of the present invention, the lens can be precisely positioned and stress is not applied to the resin lens during thermal expansion, so the resin lens does not deform and can be used at high temperatures. It is possible to provide a lens unit at a low cost that suppresses deterioration in performance even when

Cross-sectional view of lens positioning structure using positioning spacer Exploded sectional view of positioning structure diagram Cross-sectional view of positioning part during thermal expansion Structural sectional view of Example 1 Structural sectional view of Example 2 Structural sectional view of Example 3

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that each figure illustrates one configuration example according to the present invention, and only schematically shows the cross-sectional shape and arrangement relationship of each component to an extent that the present invention can be understood. is not limited to the illustrated example. Further, in the following description, specific conditions and the like may be used, but these materials and conditions are only one of preferred examples, and therefore, the present invention is not limited to these in any way.

FIG. 1 is a block diagram of a lens unit structure using the positioning spacer of the present invention. FIG. 2 shows the state before assembly in order to make it easier to understand the positional relationship of each surface. A resin lens PL1 formed of resin is arranged on the upper surface side SP1 of the positioning spacer SP having a hollow cylindrical structure, and a resin lens PL2 is arranged on the lower surface side SP2. The resin lens PL2 has a vertical wall part PL11 for radial alignment with the part SP4, and a straight part PL12 for alignment with the optical axis CL. It has a vertical wall part PL21 for radial alignment with the external part SP4 of the spacer SP, and a straight part PL22 for alignment with the optical axis CL, and is positioned via the positioning spacer SP. .

The outer diameter portion SP4 of the positioning spacer SP has a cylindrical shape in which the upper surface side SP1 and the lower surface side SP2 have approximately the same diameter, and the inner diameter portion SP3 is set to a shape that does not block the effective light rays of the lens.

Here, the lens effective diameter refers to a curved surface portion through which light rays necessary for lens design pass. However, even if it is a curved surface, if it is outside the area through which the necessary light rays pass according to the lens design, it will be outside the effective diameter of the lens. In this application, the outside of the lens effective diameter is referred to as a flange portion for convenience. The optical axis direction is a direction from the upper surface side SP1 of the positioning spacer SP to the lower surface side SP2 with respect to the optical axis CL shown in FIG.

The change in the lens unit positioning portion after thermal expansion will be explained with reference to FIG. 3. As the temperature rises, the resin lenses PL1 and PL2 thermally expand by the linear expansion coefficient and the increased temperature. After thermal expansion, the vertical wall portions PL11 and PL21, which are responsible for positioning the resin lenses PL1 and PL2 in the radial direction, move in a direction in which the diameter increases. On the other hand, since the positioning spacer SP has a smaller coefficient of linear expansion than the resin lenses PL1 and PL2, its thermal expansion is smaller than that of the resin lenses PL1 and PL2. As a result, there is a gap between the positioning spacer SP and the resin lenses PL1 and PL2. , spaces A1 and A2 arise. The spaces A1 and A2 become larger as the temperature increases. When the temperature decreases and returns to room temperature, the spaces A1 and A2 disappear, the positioning spacer SP and the resin lenses PL1 and PL2 come into contact again, and each member is positioned again.

With this configuration, even if the resin lenses PL1 and PL2 thermally expand at high temperatures, spaces A1 and A2 are generated in the positioning portion, so stress is not applied to the resin lenses PL1 and PL2 at high temperatures. It is possible to suppress thermal deformation.

FIG. 4 is a configuration diagram of the lens unit in the first example. The resin lenses PL1 and PL2 are positioned by the positioning spacer SP via the vertical wall parts PL11 and PL21 formed on the lens flange part and the straight parts PL12 and PL22, and the holder H has the vertical wall parts PL11 and PL21 formed on the flange part of the resin lens PL1. By positioning via the taper TP1 and press-fitting the stopper ST1 into the holder H, the resin lenses PL1 and PL2 and the positioning stopper SP are fixed inside the holder H via the resin lens PL2. The holder H, the positioning spacer SP, and the stopper ST1 are made of elastic members whose coefficient of linear expansion is smaller than that of the resin lenses PL1 and PL2.

The holder H is provided with an aperture AP that determines the angle of view and F value of the lens. Further, the resin lens PL1 and the holder H are positioned by a taper TP1, and when thermally expanded, the resin lens PL1 expands in the radial direction, so that the taper TP1 moves in the radial direction. Since the linear expansion coefficient of the holder H is smaller, a space is generated between the holder H and the taper TP1 of the resin lens PL1. After the space is generated, the resin lens PL1 also expands slightly in the optical axis direction, but since there is a space generated between the taper TP1 and the holder H, the expansion in the optical axis direction can be absorbed.

As described above, a space (clearance) is generated between the resin lenses PL1, PL2 and the positioning spacer SP due to thermal expansion, so it is difficult to suppress the influence of stress due to thermal expansion. can. Resin lenses PL1 and PL2 are not subjected to external stress during thermal expansion, so only elastic deformation occurs, and plastic deformation due to thermal expansion does not occur, so even after returning to room temperature, accuracy is maintained and there is no deformation, so the lenses Deterioration of optical performance can be prevented.

In order to maintain performance, it is desirable that the coaxiality between lenses be precisely controlled in design. In this application, in order to position the lenses with high precision, a cylindrical positioning spacer SP whose outer diameters on the upper surface side SP1 and the lower surface side SP2 are approximately the same is installed at the flange portions of the resin lenses PL1 and PL2. By fixing via the vertical wall portions PL11 and PL21 formed in and the straight portions PL12 and PL22, the interlens positions in the radial direction and the optical axis direction can be precisely controlled. The vertical wall portions PL11 and PL21 and the straight portions PL12 and PL22 formed on the flange portions of the resin lenses PL1 and PL2 can be integrally processed with the lens curved surface portion during mold processing. It becomes possible to form the above-mentioned positioning portion without error.

It is widely known that lenses are positioned with a taper formed on the flange of the lens, but in the case of a design where the distance between the lenses is large, extending the flange in the optical axis direction will increase the lens size. In addition to being large, the thickness is uneven, making it difficult to mold. In this embodiment, by effectively using the positioning spacer, it is possible to form a lens unit with a wide lens interval into a shape that allows lens molding and to precisely position the lens unit.

With this configuration, it is possible to ensure the performance of the lens unit without causing deformation of the resin lens due to thermal expansion of each component of the lens unit while ensuring positioning accuracy.

FIG. 5 is a diagram showing a second embodiment. Three lenses are used, and in order from the top side, a glass lens GL1 made of glass, resin lenses PL1 and PL2 made of resin are arranged, and the resin lenses PL1 and PL2 are made of stainless steel. Positioning is performed using the same method as in the first embodiment via positioning spacers SP. A chamfered portion is formed on both the upper and lower surfaces of the outer diameter portion of the positioning spacer SP. By forming the chamfered portion, ease of assembly is improved when inserting the resin lenses PL1 and PL2. A filter plate F that cuts light of a specific wavelength is fixed to the holder H by adhesive.

By inserting the outer diameter GL11 of the glass lens GL1 into the vertical wall portion PL13 formed in the resin lens PL1, the radial position of the glass lens GL1 is accurately positioned.

The taper formed on the flange portion of the resin lens PL2 is positioned in contact with the taper formed on the holder H. A stopper ST1 is press-fitted into the holder H, and a glass lens GL1 is fixed via the holder H.

Between the glass lens GL1 and the resin lens PL1, a light shielding plate CA1 having a circular hole in the center in the radial direction and blocking unnecessary light is installed, and between the positioning spacer SP and the resin lens PL2, a screen A light shielding plate CA2 having an opening AP that determines the corner and F value is installed. The light shielding plate CA2 is positioned in the radial direction and the optical axis direction by the vertical wall portion PL21 and the straight portion PL22 of the resin lens PL2 together with the positioning spacer SP.

With this configuration, it is possible to ensure the performance of the lens unit without causing deformation of the resin lens due to thermal expansion of each component of the lens unit while ensuring positioning accuracy.

A third embodiment will be explained with reference to FIG. In the third embodiment, four lenses are used. All four lenses are made of resin, and the resin lenses PL3, PL4, PL1, and PL2 are arranged in order from the top side. The resin lenses PL1 and PL2 are positioned in the radial direction and the optical axis direction by a method similar to that described in the first and second embodiments via a positioning spacer SP made of aluminum.

A recess PL23 formed circumferentially in the flange portion of the resin lens PL2 is inserted into a circumferentially formed portion H3 in a holder H made of stainless steel, and its radial position is determined. The concave portion formed in the resin lens PL2 and the convex portion formed in the holder H are in contact with each other on the outside of the convex portion, and are set so that there is a space on the inside. With this configuration, even if the resin lens PL2 expands due to thermal expansion, no load is applied to the positioning section.

A stopper ST1 made of aluminum is press-fitted into the holder H, and the resin lens PL3 is fixed by pressing the taper formed on the flange portion of the resin lens PL3 via the taper formed on the stopper ST1. The resin lenses PL3 and PL4 are positioned by tapers formed on their respective lenses, and the resin lenses PL4 and PL1 are similarly positioned by tapers formed at the flange portions of their respective resin lenses. When the distance between lenses is narrow, positioning using a taper like this is effective. If the difference in the linear expansion coefficients of the resins used in the lenses is 20 x E-6 or less, the difference in radial expansion of the taper used for positioning formed on each lens will be small even when thermal expansion is caused by high temperatures, and In the case of a tapered shape, the tapered surface allows slight vertical movement, so stress can be prevented from being applied to the lens.

A filter F that cuts specific wavelengths is fixed to the holder H by adhesive.

The inner diameter part SP3 of the positioning spacer SP formed of aluminum has a step-like shape in which the diameter decreases from the upper surface side to the lower surface side. By adopting such a structure, it is possible to prevent reflected light from the inner surface of the spacer from entering the resin lens PL2, and to prevent problems such as flare and ghost that degrade image quality.

Light shielding plates CA1 and CA2 having circular holes and blocking unnecessary light rays are arranged between resin lenses PL3 and PL4, and light shielding plate CA3 is arranged between resin lenses PL4 and PL1. A light-shielding plate CA4 that determines the angle of view and F value is arranged between the positioning spacer SP and the resin lens PL2. By effectively arranging a light shielding plate that can appropriately cut off unnecessary light rays, it is possible to prevent unnecessary light rays from entering the next lens, thereby preventing a decrease in contrast.

With this configuration, it is possible to ensure the performance of the lens unit without causing deformation of the resin lens due to thermal expansion of each component of the lens unit while ensuring positioning accuracy.

F Filter H that cuts specific wavelengths Holder A1 Space A2 generated between resin lens PL1 and positioning spacer SP during thermal expansion Space AP generated between resin lens PL2 and positioning spacer SP during thermal expansion F value and angle of view Opening CL that determines optical axis H3 Convex part SP formed circumferentially on holder H Positioning spacer CA1 Light shielding plate with cylindrical hole CA2 Light shielding plate with cylindrical hole CA3 Light shielding plate with cylindrical hole CA4 Cylindrical hole Open light shielding plate GL1 Glass lens PL1 Resin lens PL2 Resin lens PL3 Resin lens PL4 Resin lens SP1 Top side of positioning spacer SP2 Bottom side of positioning spacer SP3 Bottom side of positioning spacer SP3 Inner diameter of positioning spacer SP4 Outer diameter of positioning spacer SP TP1 Resin lens Taper GL11 formed on the flange portion of PL1 Outer diameter PL11 of glass lens GL1 Vertical wall portion PL12 formed on the flange portion of PL1 Straight portion PL21 formed on the flange portion of PL1 Vertical wall formed on the flange portion of PL2 Part PL22 Straight part PL23 formed on the flange part of PL2 Concave part formed in a circumferential shape on the flange part of PL1

Claims (4)

A lens unit having resin lenses on the upper surface side and the lower surface side of a hollow cylindrical positioning spacer,
The outer diameter portions of the upper surface side and the lower surface side of the positioning spacer are approximately the same diameter,
The flange portion outside the light beam passing diameter of the resin lens has a
a vertical wall portion used for radial positioning with the positioning spacer;
a straight part used for positioning in the optical axis direction with the positioning spacer,
A lens unit characterized in that the positioning spacer has a linear expansion coefficient smaller than that of the resin lens. 2. The lens unit according to claim 1, wherein the positioning spacer is made of a metal material having a linear expansion coefficient of 30×E-6 or less. 3. The lens unit according to claim 1, wherein at least one of an upper surface and a lower surface of the positioning spacer is chamfered. 4. The lens unit according to claim 1, wherein the inner diameter hollow portion of the positioning spacer has a continuous stepped shape.

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