Camera unit, endoscope, and method for manufacturing camera unit

Abstract

[Problem] To provide a camera unit 1 having high performance and excellent yield. [Solution] A camera unit 1 comprises: an imaging unit 10 including an imaging element 11 and a cover glass 12 that has a light-receiving surface 10SB; an optical unit 20 having an optical axis, the optical unit 20 having an emission surface 20SB that is larger than the light-receiving surface 10SB; and a transparent resin bonding the light-receiving surface 10SB and the emission surface 20SB. The transparent resin forms a filet reaching the emission surface 20SB from a side surface 10SS of the cover glass 12. An outer side surface 30SS of the filet is positioned on the same plane as a side surface 20SS of the optical unit 20.

Description

Camera unit, endoscope, and method for manufacturing camera unit

[0001] The present invention relates to a camera unit in which an imaging unit is bonded to an optical unit with a transparent resin, an endoscope having a camera unit in which an imaging unit is bonded to an optical unit with a transparent resin, and a method for manufacturing a camera unit in which an imaging unit is bonded to an optical unit with a transparent resin.

[0002] Development of small camera units is progressing. In particular, it is important for the camera unit disposed at the tip of the endoscope to have a small diameter in order to make it less invasive.

[0003] WO 2023 / 218633 discloses a camera unit in which a transparent resin that bonds an imaging unit to an optical unit spreads over the light exit surface of the optical unit to form a fillet.

[0004] In order to fill holes in the corners where chipping is likely to occur when cutting a laminated wafer including multiple camera units, the transparent resin is extended further from the fillet and spreads over the entire light-emitting surface of the optical unit, so that the cut surfaces of the transparent resin extended from the fillet are exposed on the side surfaces (especially the corners) of the camera units.

[0005] In the camera unit, the transparent resin is set to spread over the entire light-emitting surface of the optical unit. The transparent resin to be cut is not a portion of the fillet whose thickness varies, but an extended portion with a uniform thickness. Therefore, the transparent resin on the imaging element side is cut in a substantially straight line.

[0006] When the transparent resin made of soft resin is cut together with the optical unit, chips may occur in the optical unit, which may degrade the optical performance of the camera unit or reduce the manufacturing yield of the camera unit.

[0007] An object of the embodiments of the present invention is to provide a high-performance camera unit with a high yield, an endoscope having a high-performance camera unit with a high yield, and a method for manufacturing a high-performance camera unit with a high yield.

[0008] A camera unit according to an embodiment of the present invention comprises an imaging unit including an imaging element and a cover glass having a light-receiving surface, an optical unit having an optical axis and an exit surface larger than the light-receiving surface, and a transparent resin bonding the light-receiving surface and the exit surface together, the transparent resin forming a fillet extending from the side surface of the cover glass to the exit surface, and the outer surface of the fillet being located on the same plane as the side surface of the optical unit.

[0009] An endoscope according to an embodiment of the present invention has a camera unit in its insertion section, the camera unit comprising: an imaging unit including an imaging element and a cover glass having a light-receiving surface; an optical unit having an optical axis and an exit surface larger than the light-receiving surface; and a transparent resin bonding the light-receiving surface and the exit surface together, the transparent resin forming a fillet extending from the side surface of the cover glass to the exit surface, the outer surface of the fillet being located on the same plane as the side surface of the optical unit.

[0010] A method for manufacturing a camera unit according to an embodiment of the present invention includes the steps of: fabricating a laminated lens wafer including a plurality of optical units each having an incident surface and an exit surface opposite the incident surface, the optical units each having an optical axis; fabricating a camera wafer by bonding an imaging unit including an imaging element and a cover glass having a light-receiving surface to the exit surface using a transparent resin; and cutting the camera wafer into a grid pattern along cutting lines that cut fillets formed by the transparent resin.

[0011] According to the embodiments of the present invention, it is possible to provide a high-performance camera unit with a high yield, an endoscope having a high-performance camera unit with a high yield, and a method for manufacturing a high-performance camera unit with a high yield.

[0012] FIG. 1 is a perspective view of a camera unit according to an embodiment of the present invention. FIG. 2 is a side view of the camera unit according to an embodiment of the present invention. FIG. 3 is a partially enlarged view of FIG. 2. FIG. 4 is a flowchart of a method for manufacturing a camera unit according to an embodiment of the present invention. FIG. 5 is a cross-sectional view for explaining a method for manufacturing a camera unit according to an embodiment of the present invention. FIG. 6 is a cross-sectional view for explaining a method for manufacturing a camera unit according to an embodiment of the present invention. FIG. 7 is a top view for explaining a method for manufacturing a camera unit according to an embodiment of the present invention. FIG. 8 is a cross-sectional view for explaining a method for manufacturing a camera unit according to an embodiment of the present invention. FIG. 9 is a perspective view of an endoscope system including a camera unit according to an embodiment of the present invention.

[0013] 1 to 3, a camera unit 1 according to an embodiment includes an imaging unit 10, an optical unit 20, and a transparent resin 30 made of transparent resin that forms a fillet 32. The symbol O indicates the optical axis of the optical unit 20. The imaging unit 10 receives a subject image focused by the optical unit 20 and converts the received image into an imaging signal.

[0014] In the following description, the drawings based on each embodiment are schematic. The relationship between the thickness and width of each part, the thickness ratio of each part, and the relative angle are different from the actual configuration. The drawings also include parts with different dimensional relationships and ratios. Some components are not shown.

[0015] The optical unit 20 has an optical axis and includes an incident surface 20SA and an exit surface 20SB opposite the incident surface 20SA. The incident surface 20SA and the exit surface 20SB are substantially square with a side length of L20. A substantially square shape means a square or a square with chamfered corners. In the ultra-compact camera unit 1, the length L20 is only 0.5 mm.

[0016] The optical unit 20 is a laminated optical system in which a plurality of optical elements 21-24 are stacked. The optical elements 21-24 are hybrid lens elements having a glass plate as a base and lenses made of resin, filter elements that remove unnecessary infrared rays, spacer elements, or the like. The laminated lens wafer has a glass wafer. As will be described later, the optical unit 20 is a wafer-level optical system (WLO) that is fabricated by cutting a laminated lens wafer including a plurality of optical units 20 using a dicing blade. The main surfaces of the plurality of optical elements 21-24 of the optical unit 20 have the same size.

[0017] In the imaging unit 10, the imaging element 11 and the cover glass 12 are bonded together by an adhesive layer (not shown). The optical unit 20 forms a subject image on the imaging element 11. The imaging element 11 is a CMOS (Complementary Metal Oxide Semiconductor) light-receiving element or a CCD (Charge Coupled Device). The imaging unit 10 is a chip-size package (CSP) fabricated by cutting a glass substrate on which multiple imaging elements 11 are arranged. The length L10 of one side of the approximately square light-receiving surface 10SA of the imaging unit 10 (cover glass 12) is 0.4 mm, which is even shorter than the length L20 of one side of the light-emitting surface 20SB of the optical unit 20.

[0018] Transparent resin 30 made of transparent resin bonds light receiving surface 10SA of imaging unit 10 (cover glass 12) and exit surface 20SB of optical unit 20. Transparent resin 30 includes an adhesive region 31 disposed between light receiving surface 10SA and exit surface 20SB, and a fillet 32 ​​disposed between exit surface 20SB and side surface 10SS of cover glass 12 (imaging unit 10).

[0019] That is, a little excess transparent resin 30 is provided to fill the gap between light-receiving surface 10SA and light-emitting surface 20SB without any gaps and to adjust the distance between light-receiving surface 10SA and light-emitting surface 20SB. As a result, transparent resin 30 overflows from between light-receiving surface 10SA and light-emitting surface 20SB, forming fillet 32.

[0020] The fillet 32 ​​extending from the side surface 10SS of the cover glass 12 to the outer periphery of the light-emitting surface 20SB is a transparent resin that fills the corners and edges that form at the joining point of two adherends. The fillet 32 ​​is often intentionally formed to improve adhesion. However, in the case of an ultra-compact camera unit 1, the specified outer dimension (L20) cannot be achieved unless the fillet 32 ​​that has spread to the light-emitting surface 20SB is cut off.

[0021] That is, when the camera wafer 1W (see FIG. 6 ) including the optical unit 20 to which the imaging unit 10 is bonded via the transparent resin 30 is cut using a dicing blade to separate the wafer, a portion of the fillet 32 ​​is also cut. Therefore, the outer side surface 30SS, which is the cut surface of the fillet 32, is located on the same plane as the side surface 20SS of the optical unit 20. The imaging element side (upper side in FIG. 3 etc.) of the outer side surface 30SS of the fillet 32 ​​forms a convex curve toward the imaging element 11.

[0022] Here, the elastic modulus E30 (e.g., 4 GPa) of the transparent resin 30 is much smaller than the elastic modulus E20 (e.g., 8000 GPa) of the glass constituting the exit surface 20SB of the optical unit 20. The elastic modulus was measured in accordance with standards (ISO 527 and JIS K7161). For this reason, when the fillet 32 ​​made of soft resin is cut together with the glass wafer using a dicing blade 40 for cutting a laminated lens wafer including a glass wafer, there is a risk of chipping the glass. If chipping occurs in the glass, the optical performance of the camera unit 1 will deteriorate and the manufacturing yield of the camera unit 1 will decrease.

[0023] 3, in camera unit 1, the cutting position and the type or amount of transparent resin 30 applied are set so that the maximum dimension L2 of outer surface 30SS of fillet 32 ​​in the optical axis direction is less than two-thirds of the maximum dimension L1 of fillet 32 ​​in the optical axis direction at side surface 10SS of cover glass 12. For example, the maximum dimension L2 of outer surface 30SS, which is the cut surface of fillet 32, is 30 μm, and the maximum dimension L1 of fillet 32 ​​at side surface 10SS is 100 μm.

[0024] A camera unit 1 having a shape that satisfies the above conditions and a fillet 32 ​​on the outer surface 30SS does not chip when cut, so optical performance is not deteriorated and manufacturing yield is high.

[0025] The thickness L12 of the cover glass is, for example, 350 μm. The thickness L3 of the transparent resin 30 between the light receiving surface 10SA and the light emitting surface 20SB is, for example, 12 μm.

[0026] When the dimension L20 of the optical unit 20 exceeds 3 mm, the camera unit can be manufactured without cutting the fillet 32. The effect of the present invention is remarkable in ultra-compact camera units that require cutting the fillet 32, for example, when the dimension L20 of the optical unit 20 is 3 mm or less, particularly 1.5 mm or less, because the fillet 32 ​​must be cut.

[0027] The effects of the present invention are particularly pronounced when the maximum dimension L2 in the optical axis direction of the outer surface 30SS, which is the cut surface of the fillet 32, is less than 100 μm and the maximum dimension L1 in the optical axis direction at the side surface 10SS of the fillet 32 ​​is less than 300 μm. Furthermore, the effects of the present invention are particularly pronounced when the elastic modulus E30 of the transparent resin 30 is 300 MPa or less and the elastic modulus E20 of the glass constituting the exit surface 20SB of the optical unit 20 is more than 100 times the elastic modulus E30 of the transparent resin 30.

[0028] <Method of Manufacturing Camera Unit> A method of manufacturing a camera unit will be described with reference to the flowchart shown in FIG.

[0029] <Step S10> Fabrication of Laminated Lens Wafer As shown in FIG. 5, a laminated lens wafer 20W is fabricated, which has an incident surface 20SA and an exit surface 20SB opposite to the incident surface 20SA and includes a plurality of optical units 20.

[0030] The laminated lens wafer 20W is formed by laminating element wafers 21W-24W, each including a plurality of optical elements.

[0031] For example, the element wafers 21W, 22W, and 23W are fabricated by providing a plurality of resin lenses 21R, 22R, and 23R on glass wafers 21GW, 22GW, and 23GW. It is preferable to use an energy-curable resin as the resin for the resin lenses 21R to 23R.

[0032] Since the resin is uncured, liquid or gel resin is placed on the glass wafer 21GW-23GW, and then a mold with a recess of a predetermined inner surface shape is pressed against it. Then, ultraviolet light is applied to harden the resin, and the resin lenses 21R-23R are produced by a molding method.

[0033] The outer surface shape of a resin lens manufactured using a molding method is a copy of the inner surface shape of the mold, so that a structure having an outer periphery that also serves as a spacer and an aspherical lens can be easily produced.

[0034] A metal film that becomes the aperture 45 is patterned on the glass wafer 21GW of the element wafer 21W. The element wafer 24W is a filter wafer that cuts off infrared rays.

[0035] The adhesive layer 50 is provided on each of the element wafers 21W-24W by using a transfer method. The adhesive layer 50 may be provided by using an inkjet method. The element wafers 21W-24W are stacked and bonded together to produce the laminated lens wafer 20W.

[0036] <Step S20> Fabricating a Camera Wafer The imaging unit 10 having the imaging element 11 and the cover glass 12 is bonded to the exit surface 20SB of the laminated lens wafer 20W using a transparent resin 30, thereby fabricating a camera wafer 1W.

[0037] Although not shown, the imaging unit 10 is manufactured by cutting an imaging wafer in which a glass wafer that becomes the cover glass 12 is bonded to an imaging element wafer including a plurality of imaging elements 11 using a transparent resin.

[0038] The imaging element 11 may be a stacked semiconductor element in which semiconductor elements that perform primary processing of the signal output from the imaging element 11 are stacked.

[0039] 6, a predetermined amount of transparent resin 30 made of liquid uncured transparent resin is applied to the emission surface 20SB. When the imaging unit 10 is placed on the emission surface 20SB, the transparent resin 30 overflows from between the emission surface 20SB and the imaging unit 10 to form a fillet 32. The transparent resin 30 is cured to produce the camera wafer 1W.

[0040] 3 (side view), the upper outer edge of the fillet 32 ​​that extends onto the side surface 10SS of the cover glass 12 (imaging unit 10) is a curve that convexly extends toward the imaging element 11. Therefore, the maximum dimension L1 of the fillet 32 ​​in the optical axis direction on the side surface 10SS of the cover glass 12 is the dimension at the center in the direction perpendicular to the optical axis.

[0041] It is preferable that, in the state of the laminated lens wafer 20W, the focal length of at least one of the plurality of optical units 20 is measured, and the thickness L3 of the transparent resin 30 is adjusted according to the focal length. For example, using a three-dimensional (XYZ) measuring device, the position and height of the region on the exit surface 20SB of the laminated lens wafer 20W mounted on a stage, where the imaging unit 10 is to be bonded, are measured. Then, the thickness of the uncured transparent resin 30, i.e., the distance between the light receiving surface 10SA and the exit surface 20SB, is adjusted based on the focal length of the optical unit 20, and in this state, the transparent resin 30 is cured (e.g., irradiated with ultraviolet light).

[0042] By using the above method, the optical performance of the camera unit 1 can be ensured even if the focal length of the optical unit 20 of the laminated lens wafer 20W changes.

[0043] 7 and 8, the camera units 1 are manufactured by cutting the camera wafer 1W into a lattice shape using a dicing blade 40. A wire saw or the like may be used for cutting instead of the dicing blade 40.

[0044] If the periphery of the fillet 32 ​​is cut while avoiding the fillet 32 ​​extending to the light exit surface 20SB, the dimension L20 in the direction perpendicular to the optical axis of the camera unit 1 increases. Therefore, when the camera wafer 1W is cut along the cutting line CL having a gap of dimension L20, the fillet 32 ​​is cut together with the laminated lens wafer 20W.

[0045] By cutting along a cutting line CL such that the maximum dimension L2 in the optical axis direction of the outer surface 30SS of the fillet 32 ​​formed by cutting is less than 2 / 3 of the maximum dimension L1 in the optical axis direction of the fillet 32 ​​on the side surface 10SS of the cover glass 12, chipping of the optical unit 20 can be prevented.

[0046] The maximum dimension L30 of the fillet 32 ​​at the exit surface 20SB in the direction orthogonal to the optical axis is often approximately the same as L1. Therefore, by cutting the camera wafer 1W along a cutting line that is less than two-thirds of the maximum dimension L30 of the fillet 32 ​​at the exit surface 20SB in the direction orthogonal to the optical axis, the maximum dimension L2 becomes less than two-thirds of the maximum dimension L1.

[0047] 9 , an endoscope 9 of this embodiment includes an insertion section 3, a grip section 4 disposed at the base end of the insertion section 3, a universal cord 4B extending from the grip section 4, and a connector 4C disposed at the base end of the universal cord 4B. The insertion section 3 includes a tip section 3A, a bending section 3B extending from the tip section 3A that is bendable and used to change the direction of the tip section 3A, and a flexible section 3C extending from the bending section 3B. A camera unit 1 is disposed at the tip section 3A. A rotatable angle knob 4A, which is an operation section that allows the surgeon to operate the bending section 3B, is disposed at the grip section 4.

[0048] The universal cord 4B is connected to the processor 5A via a connector 4C. The processor 5A controls the entire endoscope system 6, processes the image signal, and outputs an image signal. The monitor 5B displays the image signal output by the processor 5A as an endoscopic image. Note that the endoscope 9 is a flexible endoscope, but a rigid endoscope may also be used. The endoscope 9 may also be for medical or industrial use.

[0049] As described above, according to the embodiments of the present invention, it is possible to provide a high-performance, high-yield camera unit, an endoscope having a high-performance, high-yield camera unit, and a method for manufacturing a high-performance, high-yield camera unit.

[0050] The ranges of the numerical values ​​described above are not limited to the above ranges and can be increased or decreased as appropriate. The endoscope 9 may also be a rigid endoscope having a rigid insertion section 3. The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention.

Claims

1. A camera unit comprising: an imaging unit including an imaging element and a cover glass having a light receiving surface; an optical unit having an optical axis and an exit surface larger than the light receiving surface; and a transparent resin bonding the light receiving surface and the exit surface, wherein the transparent resin forms a fillet extending from the side of the cover glass to the exit surface, and the outer surface of the fillet is located on the same plane as the side of the optical unit.

2. The camera unit according to claim 1, characterized in that the maximum dimension of the outer surface of the fillet in the optical axis direction is less than two-thirds of the maximum dimension of the side surface of the cover glass in the optical axis direction.

3. The camera unit according to claim 1, wherein the outer surface of the fillet on the imaging element side is a convex curve facing the imaging element.

4. The camera unit described in claim 1, characterized in that the light receiving surface and the light emitting surface are approximately square, the length of a side of the light emitting surface is less than 3 mm, and the maximum dimension in the optical axis direction of the outer surface of the fillet is less than 0.2 mm.

5. The camera unit according to claim 1, wherein the transparent resin has an elastic modulus of 300 MPa or less.

6. The camera unit according to claim 1, wherein the light exit surface of the optical unit is made of glass having an elastic modulus that is more than 100 times that of the transparent resin.

7. The camera unit according to claim 1, which has a plurality of stacked optical elements.

8. An endoscope having a camera unit in an insertion section, wherein the camera unit comprises: an imaging unit including an image sensor and a cover glass having a light-receiving surface; an optical unit having an optical axis and an exit surface larger than the light-receiving surface; and a transparent resin bonding the light-receiving surface and the exit surface, wherein the transparent resin forms a fillet extending from the side surface of the cover glass to the exit surface, and the outer surface of the fillet is located on the same plane as the side surface of the optical unit.

9. A method for manufacturing a camera unit, comprising the steps of: fabricating a laminated lens wafer including a plurality of optical units each having an incident surface and an exit surface opposite the incident surface, and each having an optical axis; fabricating a camera wafer by bonding an imaging unit including an imaging element and a cover glass having a light-receiving surface to the exit surface using a transparent resin; and cutting the camera wafer into a grid pattern along cutting lines that cut fillets formed by the transparent resin.

10. A method for manufacturing a camera unit as described in claim 9, characterized in that the camera wafer is cut so that the maximum dimension of the outer surface of the fillet in the optical axis direction is less than 2 / 3 of the maximum dimension of the fillet on the side of the cover glass in the optical axis direction.

11. A method for manufacturing a camera unit as described in claim 9, characterized in that in the process of manufacturing the camera wafer, the focal length of at least one of the plurality of optical units is measured, uncured transparent resin is disposed between the light exit surface and the light receiving surface, and the transparent resin is cured while the distance between the light exit surface and the light receiving surface is adjusted to a value based on the focal length and maintained.

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