JP2014054312A - Electronic endoscope device and imaging module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce flare light attributable to an optical member bonded to a front surface of an imaging device and improve quality of a picked-up image.SOLUTION: In an imaging module that includes an imaging device 58, an optical member 55 bonded to a light receiving surface of the imaging device 58 for guiding incident light to an effective area of the imaging device 58, and a translucent light absorbing layer 55a laminated on a side end face perpendicular to the effective area of the optical member 55, a refraction index n2 of the light absorbing layer 55a to the optical member 55 formed of a material of a refraction index n1 is n2≒n1.

Description

  The present invention relates to an electronic endoscope apparatus and an imaging module, and more particularly, to an electronic endoscope apparatus and an imaging module with a countermeasure against flare.

  In an electronic endoscope apparatus that has a built-in imaging module at the distal end of an endoscope scope and displays a body cavity observation image of a subject imaged by the imaging module on a monitor screen, a flare is used to improve the quality of the captured image. Some measures have been taken.

  For example, in the electronic endoscope apparatus described in Patent Document 1 below, a flare stop is provided in front of a prism that changes the optical path of incident light to a substantially right angle on the light receiving surface side of the image sensor, and flare light reflected in the incident optical path is The light is not incident on the image sensor.

  However, even incident light that has passed through the flare stop described above may be reflected by, for example, the side end surface of a cover glass attached to the front surface of the image sensor to protect the light receiving surface of the image sensor. When the light enters the image sensor, the image quality of the image is deteriorated.

  In order to suppress reflection at the side end surface of the cover glass, for example, in Patent Document 2 below, a multilayer film or a single layer film made of a low refractive material is provided on the side end surface of the cover glass as an antireflection member, It is designed to absorb the light that has penetrated the water.

JP 2009-288682 A JP-A-5-75934

  In the prior art described in Patent Document 2, light that has entered the antireflection member from the side end face of the cover glass is absorbed in the antireflection member, and this intrusion light becomes stray light and leaks to the image sensor side. Can be prevented. However, of the light traveling toward the side end face of the cover glass, the light reflected at the boundary surface between the cover glass side end face and the antireflection member is reflected to the image sensor side without entering the antireflection member. . When the reflected light is received by the image sensor, the image quality of the captured image is degraded.

  Although the cover glass has been described as an example, the same applies to the case where the imaging element is directly attached to another optical member such as a prism described in Patent Document 1, for example, and it is necessary to suppress reflection on the side end surface of the optical member. There is.

  An object of the present invention is to mount an imaging module capable of suppressing the light reflected by the side end surface of an optical member such as a cover glass from entering the imaging element and improving the image quality of the captured image, and the imaging module. An electronic endoscope apparatus is provided.

  The imaging module of the present invention includes an imaging element, an optical member that is bonded to the light receiving surface of the imaging element and guides incident light to an effective area of the imaging element, and a side end surface that is perpendicular to the effective area of the optical member. An imaging module including a laminated translucent light absorption layer, wherein the refractive index n2 of the light absorption layer is set to n2≈n1 with respect to the optical member formed of a material having a refractive index n1. And

  An electronic endoscope apparatus according to the present invention is characterized in that the imaging module described above is built in a distal end portion of an endoscope scope.

  According to the present invention, since the light reflected by the side end surface of the optical member can be reduced as much as possible, flare light caused by the side end surface of the optical member can be suppressed, a high-quality image can be taken, and the size of the apparatus can be reduced. Can be achieved.

1 is an overall configuration diagram of an electronic endoscope apparatus according to an embodiment of the present invention. It is a front end surface front view of the front-end | tip part of the electronic endoscope shown in FIG. It is a longitudinal cross-sectional view of the front-end | tip part of the electronic endoscope shown in FIG. FIG. 4 is an enlarged schematic cross-sectional view of an image sensor portion of FIG. It is a disassembled perspective view of the prism of the embodiment shown in FIG. 3, a flare stop, and an image sensor. It is explanatory drawing of the incident light and reflected light in an interface with the light absorption film (light absorption layer) of a cover glass end surface. It is explanatory drawing of the specific example in incident light with an image height of 1.4 mm and an image height of 1.6 mm. It is a table figure which shows the conditions of FIG. It is an enlarged view of the interface part of the cover glass of FIG. 7, and a light absorption film.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram showing the entire system of an electronic endoscope apparatus according to an embodiment of the present invention. An electronic endoscope apparatus (endoscope system) 10 according to the present embodiment includes an endoscope scope 12, a processor device 14 and a light source device 16 that constitute a main body device. The endoscope scope 12 includes a flexible insertion portion 20 that is inserted into a body cavity of a patient (subject), an operation portion 22 that is connected to a proximal end portion of the insertion portion 20, a processor device 14, and a light source. And a universal cord 24 connected to the device 16.

  A distal end portion 26 is connected to the distal end of the insertion portion 20, and an imaging chip (imaging device) 54 (see FIG. 3) for intra-body cavity imaging is built in the distal end portion 26. Behind the distal end portion 26 is provided a bending portion 28 in which a plurality of bending pieces are connected. When the angle knob 30 provided in the operation section 22 is operated, the bending section 28 is bent / moved in the vertical and horizontal directions by pushing / pulling the wire inserted in the insertion section 20. Thereby, the front-end | tip part 26 is orientated in the desired direction within a body cavity.

  A connector 36 is provided at the base end of the universal cord 24. The connector 36 is of a composite type and is connected to the light source device 16 in addition to being connected to the processor device 14.

  The processor device 14 supplies power to the endoscope scope 12 via a cable 68 (see FIG. 3) inserted into the universal cord 24, controls the driving of the imaging chip 54, and connects the cable 68 from the imaging chip 54. The received image signal is received, and various signal processing is performed on the received image signal to convert it into image data.

  The image data converted by the processor device 14 is displayed as an endoscopic image (observation image) on a monitor 38 connected to the processor device 14 by a cable. The processor device 14 is also electrically connected to the light source device 16 via the connector 36, and comprehensively controls the operation of the electronic endoscope device 10 including the light source device 16.

  FIG. 2 is a front view showing the distal end surface 26 a of the distal end portion 26 of the endoscope scope 12. As shown in FIG. 2, an observation window 40, an illumination window 42, a forceps outlet 44, and an air / water supply nozzle 46 are provided on the distal end surface 26 a of the distal end portion 26.

  The observation window 40 is arranged eccentric to the center and one side of the distal end surface 26a. Two illumination windows 42 are arranged at symmetrical positions with respect to the observation window 40, and irradiate illumination light from the light source device 16 to a site to be observed in the body cavity.

  The forceps outlet 44 is connected to a forceps channel 70 (see FIG. 3) disposed in the insertion portion 20 and communicates with a forceps port 34 (see FIG. 1) provided in the operation portion 22. Various treatment tools having an injection needle, a high-frequency knife or the like disposed at the distal end are inserted into the forceps port 34, and the distal ends of the various treatment instruments are ejected from the forceps outlet 44 into the body cavity.

  The air supply / water supply nozzle 46 is cleaned from the air supply / water supply device built in the light source device 16 in accordance with the operation of the air supply / water supply button 32 (see FIG. 1) provided in the operation unit 22. Water or air is jetted toward the observation window 40 or the body cavity.

  FIG. 3 is a longitudinal sectional view of the distal end portion 26 of the endoscope scope 12. As shown in FIG. 3, an imaging module 50 is disposed in the back of the observation window 40. The imaging module 50 of this embodiment includes an objective lens optical system 51, a prism 56, a cover glass 55, and an imaging chip 54.

  The imaging module 50 has a lens barrel 52 that holds an objective lens optical system 51 for capturing image light from a site to be observed in a body cavity. The lens barrel 52 is attached so that the optical axis of the objective lens optical system 51 is parallel to the central axis of the insertion portion 20. Connected to the rear end of the lens barrel 52 is a prism 56 that guides the image light of the site to be observed via the objective lens optical system 51 toward the imaging chip 54 by bending it at a substantially right angle.

  The imaging chip 54 includes a single-chip color image imaging device 58 in which a signal reading circuit is formed on a semiconductor chip and a photoelectric conversion layer made of an organic layer formed thereon, and driving of the imaging device 58 and input / output of signals. The peripheral circuit 60 for performing the imaging is an imaging chip formed on a semiconductor chip, and is mounted on a support substrate 62.

  The lower surface side of the protective cover glass 55 made of a transparent glass parallel plate is affixed and fixed to the imaging surface (light receiving surface) 58 a of the image sensor 58 with an adhesive, and the upper surface of the cover glass 55 is the light of the prism 56. Affixed to the exit surface with an adhesive. That is, the imaging surface 58a and the light exit surface of the prism 56 are arranged to face each other in parallel.

  A plurality of input / output terminals 62 a are arranged in the width direction of the support substrate 62 at the rear end portion of the support substrate 62 extending toward the rear end of the insertion portion 20. A signal line 66 for mediating the exchange of various signals with the processor device 14 through the universal cord 24 is joined to the input / output terminal 62a. The input / output terminal 62a is electrically connected to the peripheral circuit 60 in the imaging chip 54 via wiring, bonding pads, etc. (not shown) formed on the support substrate 62.

  The signal lines 66 are collectively inserted into a flexible tubular cable 68. The cable 68 is inserted through each of the insertion unit 20, the operation unit 22, and the universal cord 24 and is connected to the connector 36.

  Although not shown in FIGS. 2 and 3, an illumination unit is provided in the back of the illumination window 42. The illumination unit is provided with a light guide end of a light guide that guides illumination light from the light source device 16, and the light exit end is provided facing the illumination window 42. Like the cable 68, the light guide is inserted through each of the insertion unit 20, the operation unit 22, and the universal cord 24, and the incident end is connected to the connector 36.

  The image sensor 58 used in this embodiment is a photoelectric conversion layer stacked type, but may be a known CCD image sensor or CMOS image sensor in which a plurality of photodiodes are two-dimensionally arranged on the surface of a semiconductor chip.

  FIG. 4 is an enlarged schematic cross-sectional view of the image sensor 58 portion shown in FIG. The photoelectric conversion layer stacked type imaging device 58 is formed on the semiconductor substrate 110. On the surface of the semiconductor substrate 110, a MOS circuit 71 such as a CMOS circuit as a signal readout circuit is formed for each pixel. The signal readout circuit may be a CCD type. JP-A-2011-243945, which was previously filed by the applicant of the present application and has already been disclosed, is known as a photoelectric conversion layer stacked type imaging device.

  An insulating layer 111 is laminated on the surface of the semiconductor substrate 110, and a wiring layer 112 is embedded in the insulating layer 111. The wiring layer 112 also functions as a shielding plate that prevents incident light that has leaked through the upper layer from entering the signal readout circuit 71 and the like.

  On the surface of the insulating layer 111, a plurality of pixel electrode films 113 are formed which are divided for each pixel and are arranged in a square lattice when viewed from above (light incident direction). Each pixel electrode film 113 is provided with a vertical wiring 114 extending up to the surface of the semiconductor substrate 110, and each vertical wiring 114 is connected to a signal charge storage unit (not shown) formed on the surface of the semiconductor substrate 110. .

  The signal readout circuit 71 provided for each pixel reads out a signal corresponding to the signal charge amount stored in the corresponding signal charge storage unit to the outside as a subject image signal. In the present embodiment, the pixel electrode film 113 is provided in the effective pixel region (imaging region).

  On the plurality of pixel electrode films 113 arranged in a square lattice pattern, a light receiving layer 103 having a photoelectric conversion function is laminated in a single configuration in common with each pixel electrode film. The upper electrode film (also referred to as a counter electrode film or a common electrode film) 104 is stacked on the pixel electrode film 113 as an upper layer on the light incident side. The light receiving surface 58a described in FIG. 3 corresponds to the light receiving layer 103, and a photoelectric conversion portion is formed by the light receiving layer 103, the lower electrode film (pixel electrode film) 113 and the upper electrode film 104 sandwiching the light receiving layer 103 vertically. .

  The upper electrode film 104 is electrically connected to the counter voltage supply electrode film 115 exposed on the surface of the insulating layer 111 through the wiring 116, and a required voltage is applied from the outside of the imaging device through the wiring 116. Is done.

  A protective layer 117 is laminated on the upper electrode film 104, and a color filter 120 corresponding to each pixel electrode film 113 is laminated thereon. For example, three primary color red (R), green (G), and blue (B) color filters are arranged in a Bayer array, or complementary color color filters are stacked. An overcoat layer (protective layer) 118 is laminated on the color filter layer 120.

  On the overcoat layer 118, a protective cover glass 55 made of a glass parallel plate is attached and fixed with an adhesive. In the present embodiment, the cover glass 55 has a rectangular shape, and a translucent light absorption film (light absorption layer) 55a is applied to the side end faces of the four circumferences. The cover glass 55 is formed slightly larger than the effective pixel area so as to completely cover the entire rectangular effective pixel area (effective area: imaging area) of the image sensor 58.

  The imaging device 58 of the present embodiment is not provided with a microlens (top lens) that is stacked for each pixel by a normal image sensor, and is a non-microlens mounting type. Therefore, the color filter layer 120 and the overcoat layer 118 are in close contact with no gap, and the surface of the overcoat layer 118 is flat.

  For this reason, the cover glass 55 can be directly attached to the surface of the overcoat layer 118 of the image sensor 58. In addition, since there is no gap formed between the light emitting surface of the prism 56 and the light receiving layer 103, it is not necessary to prevent moisture in the gap, and there is no need to worry about deterioration in image quality of a captured image due to moisture.

  Since the upper electrode film 104 described above needs to make light incident on the light receiving layer 103, it is made of a conductive material transparent to the incident light. As a material of the upper electrode film 104, a transparent conductive oxide (TCO) having a high transmittance for visible light and a small resistance value can be used.

  A metal thin film such as Au (gold) can also be used. However, if the film thickness is reduced in order to obtain a transmittance of 90% or more, the resistance value increases drastically, so TCO is preferable. As TCO, indium tin oxide (ITO), indium oxide, tin oxide, fluorine-doped tin oxide (FTO), zinc oxide, aluminum-doped zinc oxide (AZO), titanium oxide, and the like can be preferably used. ITO is most preferable from the viewpoints of process simplicity, low resistance, and transparency. Note that the upper electrode film 104 is configured to be common to all pixels in the embodiment, but may be configured to be divided for each pixel and connected to a power source.

  The lower electrode film (pixel electrode film) 113 is a thin film divided for each pixel, and is made of a transparent or opaque conductive material. As a material of the lower electrode film 113, a metal such as Cr, In, Al, Ag, W, TiN (titanium nitride), or TCO can be used.

The protective layer 117 and the overcoat layer 118 are made of a transparent insulating material, silicon oxide film, silicon nitride film, zirconium oxide, tantalum oxide, titanium oxide, hafnium oxide, magnesium oxide, alumina (Al ₂ O ₃ ), polyparaxylene series Resin, acrylic resin, all-fluorine transparent resin (Cytop), etc.

  The protective layer 117 and the overcoat layer 118 are formed by a known technique such as a chemical vapor deposition method (CVD method) or an atomic layer deposition method (ALD ALCVD), and are deposited by a CVD method, an atomic layer deposition method, or the like as necessary. It may be a multilayer film combined with a plurality of insulating films. The smoothing layer and the overcoat layer are formed and then smoothed and flattened by removing the convex portions by chemical mechanical polishing (CMP).

  The thickness of the protective layer 117 and the overcoat layer 118 fulfills their respective functions and is desirably as thin as possible, preferably 0.1 μm to 10 μm.

  FIG. 5 is an exploded perspective view of the imaging chip 54, the cover glass 55, and the prism 56. The illustration of the objective lens optical system 51 to which the prism 56 is attached is omitted. A cover glass 55 is attached and fixed to the surface of the image pickup device 58 of the image pickup chip 54 with an adhesive, and the surface of the cover glass 55 is attached to the light emitting surface of the prism 56 with an adhesive, whereby the image pickup module is mounted. Manufactured.

  FIG. 6 is an end cross-sectional view of the cover glass 55. The cover glass 55 is formed by forming a transparent material having a refractive index n1 into a parallel plate shape, and a light absorption film 55a made of a semi-transparent film having a refractive index n2 is formed on a side end surface of the four circumferences thereof.

  In the present embodiment, two countermeasures (a) and (b) described below are used in combination as a countermeasure against flare light.

  Countermeasure (a): The relationship between the refractive indexes of both is set to n1≈n2 so that the light is not reflected at the boundary surface between the cover glass 55 and the light absorption film 55a.

  Countermeasure (b): In an effective area of the imaging chip 54, the light (flare light) reflected by the boundary surface between the cover glass 55 and the light absorption film 55a does not enter the effective imaging area (effective area) of the imaging chip 54. On the other hand, the size of the cover glass 55 is determined.

  First, the countermeasure (a) will be described. The light 80 incident on the boundary surface between the side end surface of the cover glass 55 and the light absorption film 55a is reflected light 81 reflected by the boundary surface and transmitted light 82 entering the light absorption film 55a through the boundary surface. Divided. The reflected light 81 is incident on the image sensor 58 side when the incident light 80 is obliquely incident light.

  The reflectivity R of how much of the incident light 80 becomes the reflected light 81 is determined by the refractive indexes n1 and n2 and the incident angle to the boundary surface. As is well known, the reflectance R of light perpendicularly incident on the boundary surface is represented by the square of {(n1-n2) / (n1 + n2)}. For this reason, the reflected light 81 can be eliminated in principle by setting the refractive index n2 of the light absorption film 55a to the refractive index n1 of the cover glass 55. That is, n1 = n2 means that there is no optical interface between the cover glass 55 and the light absorption film 55a, and this is also true for obliquely incident light.

However, since it is difficult to actually select a material that satisfies n1 = n2 with another material, the refractive index n2 of the light absorption film 55a is set to 0.9 × n1 ≦ n2 ≦ 1.1 × n1.
The degree value is also good. With such a difference, the ratio of the reflected light at the boundary surface can be reduced to a practically no problem level.

  Or it is good also considering the base material of the cover glass 55, and the base material of the light absorption film 55a as the same material. For example, in the end face portion of the cover glass 55, for absorption of light, pigment particles or pigment particles, which are filter materials having high absorptance with respect to a specific wavelength, or ND (darkening) filter materials such as carbon black particles are mixed. Alternatively, a translucent light absorbing film 55a may be formed. The specific wavelength is preferably 400 nm to 700 nm used in white light photography, and may be, for example, a central green wavelength of 550 nm.

  In this case, even if light absorption fine particles are mixed and the refractive index of the light absorption film 55a is different from the refractive index of the base material of the cover glass 55, 0.9 × n1 ≦ n2 ≦ 1.1 × n1. Within the range, it is possible to suppress the influence of flare light. By setting the refractive index to n1≈n2, the thickness of the light absorption film 55a can be reduced, the cover glass can be downsized, and the entire imaging module can be downsized.

  The refractive index varies depending on the color, that is, the wavelength of light. For this reason, it is desirable that the wavelength n1 = n2 (or n1≈n2) be green (wavelength near 550 nm) in consideration of a wavelength band of 400 nm to 700 nm often used in endoscopes.

  Next, countermeasure (b) will be described. FIG. 7 is a diagram showing the relationship between the incident light incident on the cover glass 55 and the image height. Of the light incident on the cover glass 55 from the optical system exit pupil having an F value of “8”, incident light having an image height of 1.4 mm and incident light having an image height of 1.6 mm are specifically calculated. The calculation conditions are as shown in FIGS. 8 (a) and 8 (b).

  Now, it is assumed that the cover glass 55 is bonded to the image sensor chip 58 so that the position of the image height of 1.4 mm is the end of the effective area of the image sensor 58. The position of the boundary surface between the light absorption film 55a and the cover glass 55 is 1.45 mm from the center of the optical axis. Since the light absorption film 55a may be thin, the size up to the end of the cover glass 55 is substantially 1.45 mm.

  Since incident light with an image height of 1.4 mm does not reach the end face of the cover glass 55, stray light is not generated. On the other hand, as shown in FIG. 9 which is a partially enlarged view of FIG. 7, incident light having an image height of 1.6 mm is reflected by the end face of the cover glass 55 to become stray light, and is positioned 1.3 mm from the optical axis center. It falls to (inside the effective area).

  That is, the optical system and the imaging system may be designed so that this stray light does not fall within the effective area. In this example, an imaging element having an effective area in a range up to an image height of 1.4 mm is used, and the distance to the end of the cover glass 55 is 1.45 mm. Then, an optical system in which light having an incident angle of the principal ray of 15.0 degrees (see FIG. 8A) with an F value “8” is not incident on the image sensor may be used.

  In the above description, with respect to incident light with an image height of 1.6 mm, if the distance to the end of the cover glass 55 is 1.6 mm, the incident light with an image height of 1.6 mm is reflected at the end of the cover glass 55. Disappears. That is, no stray light is generated. However, in this case, the size of the cover glass 55 is increased.

  The diameter of endoscope scopes in recent years has been reduced in diameter, and a diameter of 9 mm has become common, but further reduction in diameter has been achieved. For this reason, various parts used as members of the optical system and the imaging system also need to be miniaturized. The optical system of the present embodiment uses a prism 56 as shown in FIG.

  However, in the case of an endoscope scope that receives incident light that has passed through an optical lens at the light receiving surface of the image sensor without using a prism, the size of the cover glass directly affects the diameter of the endoscope scope. Therefore, the smaller the cover glass, the better.

  In the present embodiment, the cover glass can be made small because the photoelectric conversion layer stacked solid-state imaging device 58 is used. The reason for this is that, as shown in FIG. 4, there is no top lens (non-microlens mounting type), and the light receiving layer 103 is disposed above the semiconductor substrate 110, so that the cover glass 55, the light receiving layer 103, This is because the distance between the two can be reduced. That is, since this distance is narrow, the distance that the reflected light 81 in FIG. 6 travels to the effective area side is shortened, and the distance from the end position of the effective area in FIG. 9 to the end position of the cover glass 55 can be shortened. .

  Although the countermeasures (a) and (b) have been described above, in the present embodiment, both countermeasures are used together to take the countermeasure against flare. The countermeasure (a) alone or the countermeasure (b) alone is effective.

  However, for example, if a material in which the countermeasure (a) is n1 = n2 and the cover glass 55 is transparent and the light absorption film 55a is a translucent film is obtained, some reflected light is generated at the interface, Flare light is generated. Although the image quality deterioration due to the flare light is very small, when it is desired to reduce the influence of the flare light, the countermeasure (b) is used together.

  On the contrary, when the size of the cover glass 55 is reduced to be slightly larger than the effective area, there is a possibility that the light reflected by the end surface (interface with the light absorption film) of the cover glass 55 enters the effective area. Since this reflected light (flare light) is very small, there is no problem. However, when it is desired to reduce the influence of this flare light, countermeasure (a) may be used in combination.

  In the above-described embodiment, the cover glass has been described as an example. However, the present invention is not limited to the cover glass, but an optical member such as a prism having an end surface (interface with the light absorption film) perpendicular to the light receiving surface of the image sensor. But the same is true. Although described as an imaging module for an endoscope, the present invention can also be applied to an imaging module mounted on a small electronic device such as a mobile phone.

  The imaging module of the embodiment described above is an imaging device, an optical member that is bonded to the light receiving surface of the imaging device and guides incident light to the effective area of the imaging device, and is perpendicular to the effective area of the optical member. An imaging module including a translucent light absorption layer laminated on a side end surface, wherein the refractive index n2 of the light absorption layer is set to n2≈n1 with respect to the optical member formed of a material having a refractive index n1 It is characterized by that.

  In the imaging module of the embodiment, the light absorption layer is formed by mixing fine particles of an ND material or a filter material having a high absorption rate with respect to a specific wavelength into the material having the refractive index n1. .

  In the imaging module of the embodiment, n2≈n1 is 0.9 × n1 ≦ n2 ≦ 1.1 × n1.

  In addition, the imaging element of the imaging module according to the embodiment is a microlens non-mounting type and a photoelectric conversion layer stacking type.

  Moreover, the values of the refractive indexes n1 and n2 of the imaging module according to the embodiment are refractive indexes at the wavelength of green light.

  In the imaging module according to the embodiment, the position of the side end surface of the optical member overlapping the effective area is larger by 0.05 mm than the position of the end of the effective area. The value is not limited to 0.05 mm, and may be a value in the range of 0.03 mm to 0.07 mm, for example.

  In addition, an electronic endoscope apparatus according to the embodiment is characterized in that the imaging module according to any one of the above is built in a distal end portion of an endoscope scope.

  According to the embodiment described above, flare light caused by the optical member can be suppressed to a minimum, a high-quality captured image can be obtained, and the apparatus can be downsized.

  By using the optical member (cover glass in the embodiment) and the light absorption film according to the present invention, the imaging module can be reduced in size, and generation of flare light by the optical member can be suppressed. For this reason, when applied to an electronic endoscope apparatus, it is possible to achieve downsizing and to improve the quality of a captured image.

DESCRIPTION OF SYMBOLS 10 Electronic endoscope apparatus 12 Endoscope scope 14 Processor apparatus 16 Light source apparatus 38 Monitor 40 Observation window 50 Imaging module 51 Objective lens optical system 54 Imaging chip 55 Cover glass 55a Light absorption film 56 Prism 58 Imaging element

Claims (7)

  An image sensor, an optical member that is bonded to the light receiving surface of the image sensor and guides incident light to the effective area of the image sensor, and translucent light that is stacked on a side end surface that is perpendicular to the effective area of the optical member An imaging module comprising an absorption layer, wherein the refractive index n2 of the light absorption layer is n2≈n1 with respect to the optical member formed of a material having a refractive index n1.   2. The imaging module according to claim 1, wherein the light absorption layer is formed by mixing fine particles of an ND material or a filter material having a high absorption rate with respect to a specific wavelength into the material having the refractive index n <b> 1. .   3. The imaging module according to claim 1, wherein the n2≈n1 is 0.9 × n1 ≦ n2 ≦ 1.1 × n1.   4. The imaging module according to claim 1, wherein the imaging element is a microlens non-mounting type and a photoelectric conversion layer stacking type. 5.   5. The imaging module according to claim 1, wherein the values of the refractive indexes n <b> 1 and n <b> 2 are refractive indexes at a wavelength of green light.   6. The imaging module according to claim 1, wherein the position of the side end surface of the optical member overlapping the effective area is 0.05 mm from the position of the end of the effective area. Large imaging module.   The electronic endoscope apparatus which incorporated the imaging module of any one of Claim 1 thru | or 6 in the endoscope scope front-end | tip part.

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