Imaging apparatus, endoscopic system, and imaging apparatus manufacturing method

An imaging apparatus includes: an optical system configured to collect incident light; an imaging element including a light receiver configured to receive light input from the optical system and perform photoelectric conversion to generate an electrical signal; and an optical system adhesive layer configured to bond the optical system to a principal surface of the imaging element where the light receiver is provided. The optical system adhesive layer is a photosensitive transparent adhesive for which patterning is performed through a photolithography process and which has a function of determining a position of the optical system relative to the light receiver.

BACKGROUND

1. Technical Field

The disclosure relates to an imaging apparatus that is provided at a distal end of an insertion portion of an endoscope to be inserted in a subject and captures an image of an inside of the subject, an endoscopic system including the imaging apparatus, and an imaging apparatus manufacturing method.

2. Related Art

In the related art, endoscopic systems have been widely used for various examinations, in a medical field and an industrial field. Among them, endoscopic systems for medical use enable observations or the like of a suspected region by inserting, into a subject such as a patient, an elongated flexible insertion portion having a distal end portion in which a built-in imaging apparatus is provided. In this kind of endoscopic system, it is desired to miniaturize the insertion portion in consideration of ease of introduction into the subject.

In general, an imaging apparatus used in an endoscopic system is configured such that an outer peripheral portion of an objective lens serving as an objective optical system is held by a frame member (lens barrel) made of metal, so that positions of the objective lens in a radial direction and an optical axis direction are determined. As a technique for miniaturizing an insertion portion provided with a built-in imaging apparatus, there has been disclosed an endoscope imaging apparatus configured such that an interval in an optical path direction is provided on a member (lens barrel holding member) that holds a frame member (lens barrel) of an objective optical system, an outer peripheral surface of the interval portion is cut, and then the lens barrel holding member is arranged close to an upper surface side of a solid state image sensor so that the height dimension of the endoscope imaging apparatus is reduced (for example, see JP 2000-271066 A and JP 2002-45333 A).

SUMMARY

In some embodiments, an imaging apparatus includes: an optical system configured to collect incident light; an imaging element including a light receiver configured to receive light input from the optical system and perform photoelectric conversion to generate an electrical signal; and an optical system adhesive layer configured to bond the optical system to a principal surface of the imaging element where the light receiver is provided. The optical system adhesive layer is a photosensitive transparent adhesive for which patterning is performed through a photolithography process and which has a function of determining a position of the optical system relative to the light receiver.

In some embodiments, an endoscopic system configured to be inserted in a living body and capture an image of an inside of the living body is provided. The endoscopic system includes: an endoscope including the imaging apparatus at a distal end portion of the endoscope.

In some embodiments, an imaging apparatus manufacturing method according to the disclosure includes: forming a layer of an optical system adhesive layer made of a photosensitive transparent adhesive on a wafer where a plurality of light receivers are provided; performing patterning on a portion of the optical system adhesive layer through a photolithography process, the portion being a portion on which an optical system that collects incident light is arranged; performing dicing on the wafer to obtain individual pieces of imaging elements; determining a position of the optical system on an imaging element by using the optical system adhesive layer as a position determination unit; and then connecting the optical system onto the imaging element.

DETAILED DESCRIPTION

Reference will be made below to an endoscopic system including an imaging apparatus as modes for carrying out the disclosure (hereinafter, referred to as “embodiment(s)”). The disclosure is not limited by the embodiments. The same reference signs are used to designate the same elements throughout the drawings. Note that the drawings are only schematic, and a relationship between a thickness and a width of each member, a ratio of each member, or the like are different from actual ones. Different drawings may include parts with dimensions or ratios being different from one another.

First Embodiment

FIG. 1is a schematic view of an overall configuration of an endoscopic system according to an embodiment of the disclosure. As illustrated inFIG. 1, an endoscopic system1includes an endoscope2, a universal code6, a connector7, a light source device9, a processor (control device)10, and a display device13.

The endoscope2captures an in-vivo image of a subject and outputs an imaging signal by inserting an insertion portion4into the subject. An electric cable bundle inside the universal code6is extended to a distal end of the insertion portion4of the endoscope2and connected to an imaging apparatus provided at a distal end portion31of the insertion portion4.

The connector7is provided at a proximal end of the universal code6, is connected to the light source device9and the processor10, performs predetermined signal processing on an imaging signal output from the imaging apparatus at the distal end portion31connected to the universal code6, and performs analog-to-digital conversion (A/D conversion) on the imaging signal to output an image signal.

The light source device9is configured by using, for example, a white LED. Pulsed white light emitted by the light source device9passes through the connector7and the universal code6to serve as illumination light to irradiate an object from the distal end of the insertion portion4of the endoscope2.

The processor10performs predetermined image processing on the image signal output from the connector7, and controls the entire endoscopic system1. The display device13displays the image signal processed by the processor10.

An operating unit5, on which various buttons or knobs for operating an endoscope function are provided, is connected to a proximal end side of the insertion portion4of the endoscope2. A treatment tool insertion opening17for inserting a treatment tool such as a biopsy forceps, an electric scalpel, or an inspection probe into a body cavity of a subject is provided in the operating unit5.

The insertion portion4includes the distal end portion31at which the imaging apparatus is provided, a bendable portion32that is continuously provided at a proximal end side of the distal end portion31and that is bendable in a plurality of directions, and a flexible tube portion33that is continuously provided at the proximal end side of the bendable portion32. A bending tube34provided inside the bendable portion32(seeFIG. 2) is bent by an operation on a bending operation knob provided on the operating unit5, and is bendable in, for example, four directions including upward, downward, leftward, and rightward directions in accordance with pulling and loosening of a bending wire inserted in the insertion portion4.

A light guide (not illustrated) that delivers illumination light from the light source device9is arranged on the endoscope2, and an illumination lens (not illustrated) is arranged at an emission end at which the illumination light is emitted through the light guide. The illumination lens is provided at the distal end portion31of the insertion portion4, and the illumination light is emitted toward a subject.

Next, a configuration of the distal end portion31of the endoscope2will be described in detail.FIG. 2is a partial cross-sectional view on a vertical plane parallel to an optical axis direction of the distal end of the endoscope2illustrated inFIG. 1. InFIG. 2, the distal end portion31of the insertion portion4of the endoscope2and a part of the bendable portion32are illustrated.

As illustrated inFIG. 2, the bendable portion32is bendable in the four directions such as the upward, downward, leftward, and rightward directions in accordance with pulling and loosening of the bending wire inserted in the bending tube34. An imaging apparatus100is provided in the upper part of the inside of the distal end portion31that is provided in an extending manner at a distal end side of the bendable portion32, and a treatment tool channel36through which various treatment tools are extended is provided in the lower part.

The imaging apparatus100includes a lens unit40and an imaging unit50arranged at a proximal end side of the lens unit40. An edge side of an imaging element, which will be described later, is bonded to the inside of the distal end portion31with an adhesive. The distal end portion31is made of a rigid member for forming an internal space in which the imaging apparatus100is housed. An outer peripheral portion of a proximal end of the distal end portion31is covered with a pliable covering tube (not illustrated). A member on a proximal end side of the distal end portion31is made of a flexible member such that the bendable portion32can be bent.

The lens unit40includes a plurality of objective lenses40a-1to40a-3, spacers40b-1and40b-2arranged between the plurality of objective lenses40a-1to40a-3, a diaphragm member (not illustrated), and a lens frame41that supports the plurality of objective lenses40a-1to40a-3or the like. The lens unit40is fixed to the distal end portion31by being inserted and fitted to be fixed to a distal end fixing portion35inside the distal end portion31.

The imaging unit50includes a prism51that reflects light output through the objective lenses40a-1to40a-3of the lens unit40, and an imaging element53including a light receiver52that receives the light reflected by the prism51and that performs photoelectric conversion to generate an electrical signal. The imaging element53is a transverse-mount type in which a principal surface, on which the light receiver52is provided, is arranged parallel (horizontally) to the optical axes of the objective lenses40a-1to40a-3, and the prism51is arranged on the light receiver52. A flexible printed board54, to which a signal cable55is connected, is connected to a proximal end of the imaging element53. An electronic component57for driving the imaging element53, or the like is mounted on the flexible printed board54. The imaging element53in the first embodiment of the disclosure is a charge coupled device (CCD) type or complementary metal oxide semiconductor (CMOS) type semiconductor imaging element.

A proximal end of the signal cable55extends in a proximal end direction of the insertion portion4. The signal cable55is arranged by being inserted in the insertion portion4, and is extended to the connector7through the operating unit5and the universal code6illustrated inFIG. 1.

Light incident on the distal end portion31is collected by the objective lenses40a-1to40a-3, and is incident on the prism51. The light receiver52receives light emitted from the prism51, and converts the received light to an imaging signal. The imaging signal passes through the signal cable55connected to the flexible printed board54and the connector7, and is output to the processor10. In the descriptions of the present application, a side of the distal end portion31on which the light is incident, that is, a side on which the objective lenses40a-1to40a-3are arranged, will be described as a front end portion, and a side on which the prism51is provided will be described as a rear end portion.

A side surface of the imaging element53that is in contact with an inner wall surface of the distal end fixing portion35is bonded to the inner wall surface of the distal end fixing portion35with an adhesive, and a rear end side of an assembly position of the prism51on the imaging element53is sealed with sealing resin67.

Next, the imaging apparatus100according to the first embodiment of the disclosure will be described.FIG. 3Ais a perspective view of the imaging apparatus100illustrated inFIG. 2.FIG. 3Bis a cross-sectional view taken along a line A-A inFIG. 3A.

As illustrated inFIG. 3AandFIG. 3B, in the imaging apparatus100according to the first embodiment of the disclosure, the lens unit40is connected onto a mounting region of the objective lenses40a-1to40a-3on the imaging element53via a lens adhesive42, and the prism51is connected onto the light receiver52via a prism adhesive43. A lens frame41of the lens unit40for holding the objective lenses40a-1to40a-3is directly mounted on a surface of the imaging element53. An imaging element electrode56for connecting the flexible printed board54is provided on a rear end side of the imaging element53.

The objective lenses40a-1to40a-3, the spacers40b-1and40b-2, and the diaphragm member (not illustrated) are inserted in the lens frame41to form the lens unit40, and then the lens unit40is connected such that positions of the objective lenses40a-1to40a-3are determined by using the lens adhesive42provided on the principal surface of the imaging element53as a position determination unit. The lens unit40is moved to above the corresponding lens adhesive42while an upper side surface thereof is sucked by a jig or the like, the position of the lens unit40is then passively adjusted while the positions of the lens unit40and the lens adhesive42serving as a lens position determination unit are checked by a camera or the like from above, and thereafter the lens unit40is fixed to the imaging element53. Similarly, the prism51is moved to above the corresponding prism adhesive43while an upper side surface thereof is sucked by a jig or the like, the position of the prism51is then adjusted while the positions of the prism51and the prism adhesive43serving as a prism position determination unit are checked by a camera or the like from above, and thereafter the prism51is fixed to the imaging element53. To accurately perform positioning of the lens unit40and the prism51, it is preferable to set the sizes of the lens adhesive42and the prism adhesive43to be approximately equal to or slightly greater than projection planes of the lens unit40and the prism51in the direction from above.

It may be possible to use the lens unit40in which the objective lenses40a-1to40a-3and the spacers40b-1and40b-2are integrated without using the lens frame41. As the integration of the lens unit, the integration may be performed by applying an adhesive to connection surfaces of the objective lenses40a-1to40a-3or the spacers40b-1and40b-2in advance, putting the objective lens40a-3, the spacer40b-2, the objective lens40a-2, the spacer40b-1, and the objective lens40a-1in this order or the like in a frame member used for the integration, curing the adhesive, and taking the lens unit out of the frame member. When the lens frame41is not used as described above, the objective lenses40a-1to40a-3and the spacers40b-1and40b-2in circular external shapes may be cut at portions that are not used as optical paths for imaging, that is, what is called a D-cut may be performed. By performing the D-cut, a bonding area to be bonded to the imaging element53is increased, so that the objective lens can be fixed stably. Meanwhile, as a timing to perform the D-cut, it may be possible to perform the D-cut on each of the components before the components are put in place or it may be possible to collectively perform the D cut after the components are integrated, in the above-described generation steps. Furthermore, it is preferable to fill a periphery of a bonding portion between the lens unit40and the lens adhesive42with sealing resin (not illustrated) within a range in which the optical path is not obstructed, to thereby protect the bonding portion.

Next, a method for manufacturing the imaging apparatus100according to the first embodiment of the disclosure will be described.FIG. 4AtoFIG. 4Dare diagrams for explaining a process for manufacturing the imaging apparatus100illustrated inFIG. 2.

An optical system adhesive layer44made with a photosensitive transparent adhesive is provided as illustrated inFIG. 4Bon a wafer53pon which the plurality of light receivers52are provided as illustrated inFIG. 4A. A plurality of imaging elements53are manufactured by dividing the wafer53pinto individual pieces through dicing such that the light receiver52and a lens mounting region are provided in a region of each of the imaging elements53. The lens mounting region is a region in which the lens adhesive42is arranged, and the lens unit40is mounted in this region. A peripheral circuit for driving and controlling the imaging element53may be provided in the lens mounting region.

When an optical system adhesive layer44is made with a liquid photosensitive adhesive, the photosensitive adhesive is applied onto the wafer53pby spin coating. After providing the photosensitive adhesive by spin coating, pre-baking is performed, so that the optical system adhesive layer44in a semi-cured state is obtained. This enables exposure and development, which makes it possible to perform patterning on the lens adhesive42and the prism adhesive43. As the liquid photosensitive adhesive, for example, U-100 series of Taiyo Ink Mfg. Co., Ltd. may preferably be used.

When the optical system adhesive layer44is made with a film-shaped photosensitive adhesive, the film-shaped photosensitive adhesive is laminated on the wafer53p.If the film-shaped photosensitive adhesive is used, it becomes possible to easily increase a thickness of the optical system adhesive layer44. As the film-shaped photosensitive adhesive, for example, PerMX series of DuPont MRC Dry Film Ltd. and IBF series of Sumitomo Bakelite Co., Ltd. may preferably be used.

After the optical system adhesive layer44is formed, patterning is performed on the optical system adhesive layer44through a photolithography process to form the lens adhesive42and the prism adhesive43as illustrated inFIG. 4C, and dicing is performed at positions indicated by dotted lines inFIG. 4Cto obtain the divided individual imaging elements53.

Thereafter, positions of the lens unit40and the prism51are determined by using the lens adhesive42and the prism adhesive43as the position determination unit, and the lens unit40and the prism51are respectively connected to the lens adhesive42and the prism adhesive43through application of heat and pressure. The lens unit40and the prism51are temporarily fixed, and thereafter, the lens unit40and the prism51may be connected simultaneously or separately depending on adhesiveness of the adhesives. When the lens unit40and the prism51are connected separately, it may be possible to first connect the prism51with the prism adhesive43, and then adjust a connection position of the lens unit40with monitoring of an image output by the imaging element53.

The imaging apparatus100can be miniaturized by directly connecting, to the imaging element53, the lens frame41of the lens unit40or an integrated lens unit in which a lens frame is not used. However, to accurately perform positioning while adjusting the optical axes of the lens unit40and the prism51to match each other, it is necessary to accurately control an application amount or an application position of an adhesive to be used, and, it has not been easy to manufacture an imaging apparatus in which the lens unit40is directly connected to the imaging element53with high accuracy. The imaging element53used in the imaging apparatus100according to the first embodiment of the disclosure is obtained such that a photosensitive transparent adhesive is applied at a wafer level on which the plurality of light receivers52are provided, patterning is performed on the photosensitive adhesive through a photolithography process to form the lens adhesive42and the prism adhesive43, and then the wafer is divided into individual pieces. In the first embodiment of the disclosure, the lens adhesive42and the prism adhesive43are formed through the photolithography process, that is, through exposure and development using a photomask; therefore, it is possible to control relative arrangement positions of the lens adhesive42and the prism adhesive43in a planar direction with high accuracy.

Furthermore, when a liquid adhesive is used as the photosensitive adhesive, it is possible to control a thickness of the adhesive with high accuracy by spin coating, and, even when the film-shaped photosensitive adhesive is used, it is possible to control a thickness of the film with high accuracy in a film manufacturing process; therefore, it is possible to adjust the optical axis of the lens unit40and the optical axis of the prism51to match each other with high accuracy by controlling thicknesses of the lens adhesive42and the prism adhesive43with high accuracy. In the first embodiment of the disclosure, the thickness of the lens adhesive42and the thickness of the prism adhesive43become approximately equal to each other both when the liquid photosensitive adhesive is used and when the film-shaped photosensitive adhesive is used.

In the first embodiment of the disclosure, the connection positions of the lens unit40and the prism51are determined by using the lens adhesive42and the prism adhesive43, which are formed as described above, as position determination members; therefore, it is possible to obtain the imaging apparatus100in which positioning can be performed with high accuracy and which can be miniaturized.

Meanwhile, in the first embodiment of the disclosure, the imaging element is a transverse-mount type in which the principal surface, on which the light receiver is provided, is arranged parallel (horizontally) to the optical axis of the objective lens; however, it may be possible to use an imaging element of a vertical-mount type in which light is directly input from an objective lens to a light receiver without using a prism. When an imaging element of a transverse-mount type is used, it is possible to obtain a miniaturized high-precision imaging apparatus by forming a lens adhesive on the light receiver through a photolithography process and connecting the lens unit while determining a position of the lens unit by using the formed lens adhesive as a position determination unit.

Second Embodiment

FIG. 5Ais a perspective view for explaining an imaging element used in an imaging apparatus according to a second embodiment of the disclosure.FIG. 5Bis a perspective view for explaining the imaging apparatus according to the second embodiment of the disclosure. InFIG. 5AandFIG. 5B, illustration of an imaging element electrode is omitted.

Lens adhesives42aare provided in two rows parallel to the optical axes of the objective lenses40a-1to40a-3, on a principal surface of an imaging element53A used in the imaging apparatus according to the second embodiment of the disclosure. The lens adhesives42ain the two rows and the principal surface of the imaging element53A constitute a groove46a,and a connection position of the lens unit40is determined by arranging the lens unit40in the groove46a.A position of the lens unit40in a direction perpendicular to an optical axis direction is automatically determined by arranging the lens adhesives42awith high accuracy, and it is sufficient to perform adjustment in the optical axis direction and in a rotation direction. To determine the position of the lens unit40in the optical axis direction with high accuracy, it is preferable to set lengths of the lens adhesives42ain the optical axis direction and a length of the lens unit40in the optical axis direction to be approximately equal to each other.

In the second embodiment of the disclosure, it is possible to simplify adjustment in positioning of the lens unit40, and simplify adjustment of a height of the lens unit40due to contraction at the time of curing the lens adhesives42abecause the lens adhesive42ais not provided between the lens unit40and the principal surface of the imaging element53A in the groove46a.Furthermore, it is preferable to fill a periphery of a bonding portion between the lens unit40and the lens adhesives42awith sealing resin (not illustrated) within a range in which the optical path is not obstructed, to thereby protect the bonding portion.

Moreover, it may be possible to provide a plurality of lens adhesives on the principal surface of the imaging element in a plurality of directions perpendicular to the optical axes of the objective lenses40a-1to40a-3.FIG. 6Ais a perspective view for explaining an imaging element used in an imaging apparatus according to a first modification of the second embodiment of the disclosure.FIG. 6Bis a perspective view for explaining the imaging apparatus according to the first modification of the second embodiment of the disclosure. InFIG. 6AandFIG. 6B, illustration of an imaging element electrode is omitted.

Lens adhesives42bare provided in four rows in a direction perpendicular to the optical axes of the objective lenses40a-1to40a-3on a principal surface of an imaging element53B used in the imaging apparatus according to the first modification of the second embodiment of the disclosure. The lens adhesives42bin the four rows and the principal surface of the imaging element53B constitute grooves46b,and positions of the objective lenses40a-1to40a-3are determined by arranging each of the objective lenses40a-1to40a-3in the respective grooves46b.It is preferable to adjust arrangement intervals of the lens adhesives42bin accordance with the maximum length of the objective lenses40a-1to40a-3in the optical axis direction. Positions of the objective lenses40a-1to40a-3in the optical axis direction are automatically determined by arranging the lens adhesives42bwith high accuracy, and it is sufficient to perform adjustment in the direction perpendicular to the optical axis direction and in a rotation direction. To determine the positions of the objective lenses40a-1to40a-3in the direction perpendicular to the optical axis with high accuracy, it is preferable to set lengths of the lens adhesives42bin the direction perpendicular to the optical axis direction and the lengths of the objective lenses40a-1to40a-3in the direction perpendicular to the optical axis direction to be approximately equal to each other. Furthermore, it is preferable to fill a periphery of a bonding portion between the objective lenses40a-1to40a-3and the lens adhesives42bwith sealing resin (not illustrated) within a range in which the optical path is not obstructed, to thereby protect the bonding portion.

Moreover, it may be possible to provide grooves for arranging the respective objective lenses40a-1to40a-3on lens adhesives provided on the principal surface of the imaging element.FIG. 7Ais a perspective view for explaining an imaging element used in an imaging apparatus according to a second modification of the second embodiment of the disclosure.FIG. 7Bis a perspective view for explaining the imaging apparatus according to the second modification of the second embodiment of the disclosure. InFIG. 7AandFIG. 7B, illustration of an imaging element electrode is omitted.

A lens adhesive42cis provided on a principal surface of an imaging element53C used in the imaging apparatus according to the second modification of the second embodiment of the disclosure, and grooves46care provided in three rows on the lens adhesive42cin a direction perpendicular to the optical axes of the objective lenses40a-1to40a-3. The grooves46care formed by removing the lens adhesive42cthrough exposure and development, and positions of the objective lenses40a-1to40a-3are determined by arranging each of the objective lenses40a-1to40a-3in the respective grooves46c.It is preferable to adjust arrangement intervals of the grooves46cin accordance with thicknesses of the objective lenses40a-1to40a-3. Furthermore, it is preferable to set lengths and widths of the grooves46csuch that end portions of the grooves46con the principal surface side come in contact with the objective lenses40a-1to40a-3to allow for positioning when the objective lenses40a-1to40a-3are arranged. Positions of the objective lenses40a-1to40a-3in the optical axis direction and in the direction perpendicular to the optical axis are automatically determined by arranging the lens adhesive42cthrough the photolithography process with high accuracy, and it is sufficient to perform adjustment in a rotation direction. Moreover, it is preferable to fill a periphery of a bonding portion between the objective lenses40a-1to40a-3and the lens adhesive42cwith sealing resin (not illustrated) within a range in which the optical path is not obstructed, to thereby protect the bonding portion.

Third Embodiment

FIG. 8Ais a perspective view for explaining an imaging element used in an imaging apparatus according to a third embodiment of the disclosure.FIG. 8Bis a perspective view for explaining the imaging apparatus according to the third embodiment of the disclosure.FIG. 8Cis a diagram of the imaging apparatus illustrated in FIG.8B, viewed from a front end portion. InFIG. 8AandFIG. 8B, illustration of an imaging element electrode is omitted.

Lens adhesives42dare provided in two rows parallel to an optical axis of a lens unit40D, on a principal surface of an imaging element53D used in the imaging apparatus according to the third embodiment of the disclosure. Furthermore, a groove46dfor arranging the lens unit40D is provided between the lens adhesives42din the two rows.

To miniaturize the imaging apparatus, a diameter of an objective lens to be used is limited; however, in the third embodiment of the disclosure, the groove46dis formed on the imaging element53D and the lens unit40D is arranged so as to be put in the groove46d,so that it becomes possible to use the lens unit40D with a large-diameter objective lens while miniaturizing the imaging apparatus. With this configuration, it becomes possible to acquire a bright image.

The groove46dmay be formed by performing crystal anisotropic wet etching, deep reactive-ion etching, or processing using a dicing blade on the imaging element53D made of silicon. It is preferable to set a length of the groove46din the optical axis direction to be approximately equal to a length of the lens unit40D, and it is preferable to determine a length of the groove46din a direction perpendicular to the optical axis direction by taking into account the diameter of the lens unit40D and a position of the optical axis. Positions of the lens unit40D in the optical axis direction and in the direction perpendicular to the optical axis direction are automatically determined by arranging the lens unit40D so as to be put in the groove46d,and it is sufficient to perform adjustment in a rotation direction.

An outer circumference of the lens unit40D may come in contact with the groove46d;however, it is preferable to hold the lens unit40D only by the lens adhesives42dwithout contact with the groove46das illustrated inFIG. 8C. A position of the lens unit40D can be determined with high accuracy by holding the lens unit40D only by contact with the lens adhesives42dbecause position accuracy of the lens adhesives42dis higher than position accuracy of the groove46d.Furthermore, it is preferable to fill a periphery of a bonding portion between the lens unit40D and the lens adhesives42dwith sealing resin47within a range in which the optical path is not obstructed, to thereby protect the bonding portion.

A groove may include an opening on one side thereof, or may not include an opening.FIG. 9Ais a perspective view for explaining an imaging element used in an imaging apparatus according to a first modification of the third embodiment of the disclosure. InFIG. 9A, illustration of an imaging element electrode is omitted. On a principal surface of an imaging element53E, lens adhesives42eare provided in two rows parallel to an optical axis of a lens unit, and a groove46ewithout an opening on a front end side of the imaging element53E is provided between the lens adhesives42ein the two rows. By putting the lens unit in the groove46eto facilitate positioning, it becomes possible to obtain a miniaturized high-precision imaging apparatus.

Furthermore, a groove may include a closed-bottom.FIG. 9Bis a perspective view for explaining an imaging element used in an imaging apparatus according to a second modification of the third embodiment of the disclosure. InFIG. 9B, illustration of an imaging element electrode is omitted. On a principal surface of an imaging element53F, lens adhesives42fare provided in two rows parallel to an optical axis of a lens unit, and a groove46fwith a closed-bottom is provided between the lens adhesives42fin the two rows. By putting the lens unit in the groove46fto facilitate positioning, it becomes possible to obtain a miniaturized high-precision imaging apparatus.

Moreover, it may be possible to provide a plurality of grooves in accordance with objective lenses.FIG. 9Cis a perspective view for explaining an imaging element used in an imaging apparatus according to a third modification of the third embodiment of the disclosure. InFIG. 9C, illustration of an imaging element electrode is omitted. On a principal surface of an imaging element53G, lens adhesives42gare provided in two rows parallel to an optical axis of a lens unit, and three grooves46gfor arranging the objective lenses40a-1to40a-3are provided between the lens adhesives42gin the two rows. By putting each of the objective lenses40a-1to40a-3in the respective grooves46gto facilitate positioning, it is possible to obtain a miniaturized high-precision imaging apparatus.

According to some embodiments, an objective lens is directly mounted on a surface of an imaging element; therefore, it is possible to miniaturize an imaging apparatus.