MICROLENS ARRAY LAMINATE, OPTICAL DEVICE AND LiDAR SENSOR UNIT

Abstract

To provide an improved microlens array laminate that does not relay on a spot bonding system, an optical device, and a LiDAR sensor unit.SOLUTION: Provided is a microlens array laminate 140 that is formed by bonding a plurality of microlens arrays 130, in which microlenses are developed in a planar manner. An adhesive sheet 150 is arranged between the microlens arrays to be bonded. The microlens arrays to be bonded are bonded in a planar manner via the adhesive sheet. The adhesive sheet has openings formed to ensure an optical path for the microlenses. The adhesive sheet is made of a light-absorptive material (such as a black material).SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a microlens array laminate, an optical device, and a LiDAR sensor unit, and in particular to a microlens array laminate, an optical device, and a LiDAR sensor unit manufactured based on WLO (wafer level optics) technology or the like. [Background technology]

[0002] In the manufacture of this type of microlens optical device, there is a process of bonding microlens arrays together to form a microlens array laminate. In this laminate formation process, a number of microlens arrays, each of which has a microlens developed on a plane, are prepared, and these multiple microlens arrays are bonded together. Conventionally, adhesive is applied in spots (dots) to each microlens on the plane of each microlens array, and the microlens arrays are bonded together by the adhesive force of the adhesive.

[0003] In addition, in the manufacture of this type of microlens optical device, a camera-type optical device may be produced as a final product. Conventionally, in this type of camera-type optical device, a spacer is provided between the lens stack (microlens array stack) and the image sensor. The spacer adjusts the cell gap to a constant value and functions to improve the image formation on the image sensor surface. Conventionally, an adhesive is applied to the spots of the spacer corresponding to each cell of the image sensor, and the spacer is bonded to the adjacent optical component by the adhesive force of the adhesive.

[0004] In addition, conventional photolithography methods were unable to process micro-holes and therefore were unable to produce high light-blocking properties, making it impossible to manufacture thin optical components with high light-blocking properties. In particular, distance sensors used in LiDAR sensor units and the like are required to have high light-blocking properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2014-089230 [Patent Document 2] WO2020 / 145091 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have found that there is room for improvement in conventional microlens array laminates that rely on spot bonding. The present inventors have also found that there is room for improvement in conventional optical devices that rely on spot bonding.

[0007] It is therefore an object of the present invention to provide an improved microlens array laminate that does not rely on spot bonding. It is also an object of the present invention to provide an improved optical device that does not rely on spot bonding. [Means for solving the problem]

[0008] According to a first aspect of the present invention, A microlens array laminate in which a plurality of microlens arrays, each having a microlens developed in a planar shape, are bonded together, An adhesive sheet is disposed between the microlens arrays to be bonded together. The microlens array to be bonded is adhered by the adhesive sheet. A microlens array stack is provided.

[0009] In one embodiment, the adhesive sheet is arranged to cover, as an adhesive area, the areas other than the areas corresponding to the individual microlenses of the microlens array to be bonded.

[0010] In one embodiment, the adhesive sheet is made of a light absorbing material, for example a black material, which acts to reduce ghosting and flare in the image.

[0011] According to a second aspect of the present invention, An optical device in which a lens laminate is formed by bonding a plurality of types of microlenses, A first adhesive sheet is disposed between the microlens in the bottom layer of the lens stack and the adjacent optical component, the first adhesive sheet forming a planar adhesive area; the first adhesive sheet is made of a light absorbing material; the first adhesive sheet is adhered to the adjacent optical components in a planar manner; The first adhesive sheet has a spacer function for adjusting the cell gap. An optical device is provided.

[0012] In one embodiment, an image sensor is located at the bottom of the lens stack; The first adhesive sheet has an opening formed therein so as to ensure an optical path between the bottom microlens and the image sensor.

[0013] In one embodiment, an image sensor is located at the bottom of the lens stack; One of the adjacent optical components is a bottom microlens, and the other of the adjacent optical components is a glass cover adjacent to the first adhesive sheet and disposed over the image sensor.

[0014] In one embodiment, the adhesive sheet is constructed of a black material.

[0015] In one embodiment, a second adhesive sheet is disposed between a microlens in a top layer of the lens laminate and an adjacent microlens, the second adhesive sheet forming a planar adhesive area between the microlens in the top layer and an adjacent microlens; the second adhesive sheet is made of a light absorbing material; the second adhesive sheet adheres the uppermost microlens and the microlens adjacent to the uppermost microlens onto a surface thereof; The second adhesive sheet functions as a diaphragm for diaphragming light in an optical device.

[0016] In one embodiment, the first adhesive sheet and the second adhesive sheet are black.

[0017] In one embodiment, a LiDAR sensor unit is provided that includes the optical device described above.

[0018] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. [Brief description of the drawings]

[0019] [Figure 1] 1A to 1C are diagrams illustrating a lens molding process for a microlens optical device. [Diagram 2] 1A to 1C are diagrams illustrating a curing process of a microlens optical device. [Diagram 3] 1A to 1C are diagrams illustrating a demolding process of a microlens optical device. [Figure 4] 1A to 1C are diagrams illustrating a lens bonding process of a microlens optical device. [Diagram 5] 5A to 5C are diagrams illustrating a dicing process performed on a microlens array laminate produced by the lens bonding process shown in FIG. 4. [Figure 6] 6 is a diagram illustrating a microlens laminate produced by the dicing process shown in FIG. 5. FIG. [Figure 7] FIG. 1 is a diagram illustrating a conventional spot (dot) bonding method. [Figure 8] FIG. 1 is a plan view illustrating each adhesive spot in a conventional spot (dot) adhesive method. [Figure 9] FIG. 13 is a plan view illustrating one microlens along with a clear and black adhesive sheet disposed against the microlens. [Figure 10] FIG. 2 is a plan view illustrating a black or light absorbing adhesive sheet having openings formed therein for application to a microlens array. [Figure 11] 1 illustrates a camera-type optical device in which a spacer is disposed between the lens stack and the image sensor. [Figure 12] 11A and 11B are diagrams illustrating an embodiment of a camera-type optical device in which an adhesive sheet having a spacer function is disposed instead of a spacer. [Figure 13] FIG. 1 illustrates a conventional optical device. [Figure 14] 1A and 1B are diagrams illustrating an optical device in which an aperture portion is disposed between microlenses. [Figure 15] FIG. [Figure 16] 1A and 1B are diagrams illustrating an embodiment of an optical device in which a diaphragm is disposed between an adhesive sheet functioning as a spacer and a microlens. [Figure 17] 1 is an exploded view of an optical device in which a diaphragm is disposed between an adhesive sheet functioning as a spacer and a microlens. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The various steps of WLO (wafer level optics) will be described with reference to FIGS. First, a resin 120 is placed between upper and lower molds (microlens array molds) 110 by a lens molding process (FIG. 1).

[0021] Next, a curing process (FIG. 2) hardens the resin 120 by thermal curing or UV curing.

[0022] Next, the mold 110 is removed by a demolding process (FIG. 3) to take out the hardened resin microlens array 130. Here, the microlens array 130 constitutes a planar micro-optical element in which microlenses are developed on a plane or in two dimensions.

[0023] Next, a bonding process (FIG. 4) is used to bond multiple (two or more) microlens arrays 130-1, 130-2, 130-3, ... together with an adhesive to produce a microlens array laminate 140 (see FIG. 5). In this bonding process, bonding has conventionally been performed by spot bonding, but in the present invention, bonding is performed by surface bonding using an adhesive sheet 150.

[0024] Next, a dicing process (FIG. 5) is performed on the microlens array laminate 140 by a dicing device 160 to cut it into chip-like lens modules for each lens. As the dicing device 160, a device that performs dicing with a laser or a device that performs dicing with a blade is used. A lens laminate is formed by bonding multiple types of lens modules, and a camera-type optical device 500 is manufactured in which an image sensor is disposed at the bottom of the lens laminate (see FIG. 6).

[0025] Adhesive sheet bonding technology...Microlens array laminate First, the present invention relates to a microlens array laminate 140 that is fabricated through a lamination process (FIG. 4) of microlens arrays (130-1, 130-2, 130-3, . . . ).

[0026] Conventionally, when bonding a plurality of microlens arrays, as shown in Figs. 7 and 8, adhesive is applied in spots (dots) to the four corners S of each microlens section. In Fig. 7, one microlens section is illustrated, and adhesive is applied in spots (dots) to the four corners S of the section. In reality, adhesive is applied in spots (dots) to each corner of each microlens section in the microlens array laminate (each of four adjacent sections is shown as a 90-degree sector x 4 circle) as shown in Fig. 8. In the case of this spot-like bonding method, since the area of ​​the spot-like bonding area is small relative to the area of ​​the microlens section, it is difficult to ensure sufficient adhesive strength. In addition, in an application in which 20,000 microlenses are deployed in an array on a 200 mm wafer, the number of spot bonds reaches 80,000, making the bonding work time-consuming. In addition, there is a problem that the adhesive overflows to areas outside the intended spot bonding area, resulting in a decrease in yield.

[0027] In contrast to spot bonding, the present invention uses an adhesive sheet 150 (see FIG. 4) that provides a surface area of ​​adhesive between the microlens arrays to be bonded.

[0028] FIG. 9 is an explanatory diagram showing how an adhesive sheet is arranged for one microlens. The leftmost part of FIG. 9 shows a simplified view of one microlens 240 itself. The center part of FIG. 9 shows an adhesive sheet 250A arranged on the surface surrounding one microlens. The adhesive sheet 250A may be a transparent material, but is preferably a light-absorbing material. In addition, the microlenses may be bonded under a heated state, and the adhesive sheet 250A is preferably a material that exhibits the required adhesiveness under this heated state.

[0029] Shown on the right side of FIG. 9 is a light-absorbing adhesive sheet, such as a black adhesive sheet 250B, that is placed on the surface surrounding one of the microlenses.

[0030] Preferably, openings are formed in the adhesive sheets 250A and 250B so that the adhesive sheets 250A and 250B are not present in the area corresponding to the microlens 240. The openings in the adhesive sheets 250A and 250B provide an optical path for the microlens. In particular, when the adhesive sheets are made of a light-absorbing material such as black (for example, a black material), the transmitted light of the lens substantially passes through the openings, so that it is possible to provide the transmitted light of the lens with less ghost and flare.

[0031] Compared with the spot bonding method (FIGS. 7 and 8), the bonding area of ​​the microlens arrays bonded using the adhesive sheet method (FIG. 9) is larger, so that the microlens arrays can be bonded more reliably to each other.

[0032] Fig. 10 shows a specific example of an adhesive sheet 350 used for a microlens array. Openings are formed at locations corresponding to the individual microlenses of the microlens array. In the example of Fig. 10, it is assumed that the outer periphery of the microlens array is rectangular, but if the outer periphery of the microlens array is circular, an adhesive sheet with a circular outer periphery can be used to match the shape of the microlens array. The openings in the adhesive sheet 350 can be formed, for example, by a laser.

[0033] Spacer mounting using adhesive sheet...Optical device Secondly, the present invention relates to an optical device, particularly a camera-type optical device (see FIG. 6), in which a lens stack is formed by bonding a plurality of types of microlenses and an image sensor is disposed at the bottom of the lens stack. Various applications are known for this type of camera-type optical device, and the present invention can be applied to various applications. Examples of applications include a 3D camera application for face recognition, an AR (augmented reality) application that can be applied even in the dark using an infrared sensor, a VR (virtual reality) application, an endoscope application, and a distance measurement application for adjusting the distance between vehicles.

[0034] Camera-type optical devices of this type are shown in Figures 11 and 12 with reference numerals 600 and 700. In this type of camera-type optical device, a spacer is provided between the lens stack and the image sensor.

[0035] 11, the lens stack is configured by bonding together microlenses 602, 604, 606, and 608, and an image sensor 618 is disposed at the bottom of the camera-type optical device 600. Between the image sensor 618 and the bottommost microlens 608 of the lens stack, and preferably between a cover glass 616 disposed on the image sensor 618 and the microlens 608, a spacer 614 is disposed to adjust the cell gap to a constant value. Conventionally, the spacer 614 and adjacent optical components (the cover glass 616, the microlens 608) have been bonded together with an adhesive.

[0036] In the camera-type optical device 700 of FIG. 12, the lens stack is configured by bonding microlenses 702, 704, and 706 together, and an image sensor 718 is disposed at the bottom of the camera-type optical device 700. Between the image sensor 718 and the microlens 706 at the bottom (lowest layer of the lens stack), preferably between the cover glass 716 disposed on the image sensor 718 and the microlens 706, a spacer 714 is disposed to adjust the cell gap to a constant value. Conventionally, the spacer 714 and the adjacent optical components (cover glass 716, microlens 706) are bonded by an adhesive. In contrast, in the present invention, instead of the combination of the spacer and the adhesive, an adhesive sheet 720 is used as a first adhesive sheet (see FIG. 12).

[0037] The adhesive sheet 720 has both a spacer function and an adhesive function, which increases the productivity of the camera-type optical device. In addition, the adhesive sheet 720 secures an optical path from the microlens 706 to the image sensor 718 through the opening, and by forming the adhesive sheet 720 from a light-absorbing material, for example, a black material, an image with reduced ghosts and flares can be obtained through the image sensor 718.

[0038] The structure of the adhesive sheet described in the above-mentioned embodiment can also be applied to optical devices such as LiDAR sensor units.

[0039] 13 is a diagram showing an optical device such as a conventional LiDAR sensor unit. Light 810 that has passed through a lens 802 passes through an opening 806 of an aperture section 804 that narrows down the light, and is collected on a light receiving section 808. In a conventional optical device such as a LiDAR sensor unit, the lens 802, the aperture section 804, and the light receiving section 808 are configured separately. Therefore, the structure of the adhesive sheet described in the above-mentioned embodiment is also applied to the aperture section.

[0040] Fig. 14 is a diagram showing an optical device of the present invention. The difference from Fig. 11 is that an aperture section 902 for narrowing down light is provided between the microlenses 602 and 604, and that there is no image sensor 618. However, since the other configuration is the same as that of Fig. 11, a description thereof will be omitted. As shown in Fig. 15, an aperture section 904 is formed in the aperture section 902. The aperture section 904 provides an optical path for the microlens. Moreover, the aperture section 902 is made of a light-absorbing material such as black.

[0041] 14, the aperture portion 902 can bond the microlenses 602 and 604 together. That is, the aperture portion 902 can be disposed between the microlens 602 in the uppermost layer of the lens stack and the microlens 604 adjacent to the uppermost microlens 602, thereby bonding the microlenses 602 and 604 together.

[0042] In addition, the diaphragm portion 902 is made of a light absorbing material such as black, and therefore has a function of blocking light.

[0043] Therefore, by adopting such a configuration, it is possible to provide a diaphragm portion that has both a light blocking function and an adhesive function.

[0044] Fig. 16 is a diagram showing an optical device of the present invention. The difference from Fig. 12 is that an aperture section 902 for narrowing down the light is provided between the microlenses 702 and 704, and that there is no image sensor 718. However, since the other configuration is the same as that of Fig. 12, a description thereof will be omitted. The aperture section 902 is made of a light-absorbing material such as black. The above-mentioned adhesive sheet 250B is used as the aperture section 902.

[0045] Fig. 17 is a top-bottom exploded view of the optical device of Fig. 16. The aperture section 902 is provided between the microlens 702 in the uppermost layer of the lens stack and the microlens 704 adjacent to the microlens 702. The aperture section 902 can bond the microlenses 702 and 704 together. Also, instead of the combination of a spacer and an adhesive, an adhesive sheet 720 is used. That is, the cover glass 716 and the microlens 706 are bonded by the adhesive sheet 720.

[0046] 16 and 17, adhesive sheet 720 is used as the first adhesive sheet, and constriction portion 902 is used as the second adhesive sheet.

[0047] Therefore, in a conventional optical device, the lens 802, the aperture section 804, and the light receiving section 808 are separate components (see FIG. 13), but by adopting the configuration shown in FIG. 17, the lens, the aperture section, and the light receiving section can be integrated. Also, it is possible to provide an aperture section that has both a light blocking function and an adhesive function.

[0048] The optical devices shown in Fig. 14 to Fig. 17 can be used in distance sensors used in LiDAR sensor units and the like. Therefore, the distance sensor used in LiDAR sensor units and the like equipped with the optical device of the present invention can have high light blocking properties. In addition, the distance sensor used in LiDAR sensor units and the like equipped with the optical device of the present invention can integrate a lens, an aperture section, and a light receiving section.

[0049] In addition, it is preferable that the distance sensor used in the LiDAR sensor unit etc. equipped with the optical device of the present invention has 40 μm holes drilled at a pitch of about 6000. In the conventional photolithography method, the optical density (OD value) was about 2, but by forming the adhesive sheet from a light-absorbing material such as black and drilling 40 μm holes at a pitch of about 6000, the OD value can be made 3 or more.

[0050] Although the detailed description is now complete, various modifications and improvements within the scope of the present invention will be apparent to those skilled in the art.

Claims

1. A microlens array laminate in which a plurality of microlens arrays, each having a microlens developed in a planar shape, are bonded together, An adhesive sheet is disposed between the microlens arrays to be bonded together. The microlens array to be bonded is bonded in a planar manner via the adhesive sheet. Microlens array stack.

2. The microlens array laminate according to claim 1 , wherein the adhesive sheet is arranged so as to cover, as an adhesive area, areas other than areas corresponding to individual microlenses of the microlens array to be laminated.

3. The microlens array laminate of claim 1 , wherein the adhesive sheet is made of a light absorbing material.

4. The microlens array laminate of claim 3 , wherein the adhesive sheet is black.

5. An optical device in which a lens laminate is formed by bonding a plurality of types of microlenses, a first adhesive sheet is disposed between the microlens in the bottom layer of the lens stack and an adjacent optical component, the first adhesive sheet forming a planar adhesive area; the first adhesive sheet is made of a light-absorbing material; the first adhesive sheet is adhered to the adjacent optical components in a planar manner; the first adhesive sheet has a spacer function for adjusting a cell gap; Optical devices.

6. an image sensor is disposed at the bottom of the lens stack; The optical device according to claim 5 , wherein an opening is formed in the first adhesive sheet so as to ensure an optical path between the bottom microlens and the image sensor.

7. an image sensor disposed at the bottom of the lens stack; 6. The optical device of claim 5, wherein one of the adjacent optical components is the bottom microlens and the other of the adjacent optical components is a glass cover adjacent to the first adhesive sheet and positioned over the image sensor.

8. a second adhesive sheet is disposed between the microlens in the uppermost layer of the lens laminate and a microlens adjacent to the uppermost microlens, the second adhesive sheet forming a planar adhesive area between the microlens in the uppermost layer and an adjacent microlens; the second adhesive sheet is made of a light absorbing material; the second adhesive sheet adheres the microlens of the uppermost layer and a microlens adjacent to the microlens of the uppermost layer onto a surface thereof; The optical device according to claim 5 , wherein the second adhesive sheet functions as an aperture for narrowing down light in the optical device.

9. The optical device of claim 8 , wherein the first adhesive sheet and the second adhesive sheet are black.

10. A LiDAR sensor unit equipped with the optical device according to claim 8.

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