JPH10146312A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shield an incidence of the external light on a peripheral part of an image pickup surface of a solid image pickup element, and obtain an endoscope image having an excellent image quality by arranging an opening part of a light shielding mask so as to be eccentric in the desired direction to the optical axis of an observing optical system. SOLUTION: An image pickup device 20 arranged in an inserting part tip part of an electronic endoscope is composed of an objective lens unit 21 being an observing optical system, an SID 22 where an image pickup surface 22a is arranged in its focal position, a light shielding mask 27 adhered and fixed to a front face of cover glass 23 or the like, In this case, an opening part 27a of the light shielding mask 27 is formed by being positionally dislocated to the image pickup surface 22a so that the image pickup surface 22a becomes narrow only on the side positioned on the opposite side of the side where a clamp channel is arranged in order to prevent its reflected light from being made incident on the image pickup surface 22a by being reflected by a side surface of the cover glass 23 when the illuminating light irradiated toward an object is reflected to a gripping clamp projecting from a tip surface of the endoscope. Therefore, the harmful reflected light incident on the image pickup surface 22a can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device provided at a distal end of an insertion portion of an endoscope.

[0002]

2. Description of the Related Art In recent years, with the development of electronic technology, computerization has advanced in the field of endoscopes, and charge-coupled devices (CCDs) have been developed.
Various types of electronic endoscopes in which an image pickup device using a solid-state image pickup device (hereinafter referred to as SID) as an image pickup means and arranged at the distal end of an insertion section are used.

[0003] An imaging device provided at a distal end hard portion at the distal end of an insertion portion of the electronic endoscope includes an observation optical system composed of a plurality of lens systems in order from the distal end side, and an optical image captured by the observation optical system is converted into an electric signal. And a circuit board on which components for amplifying the output of the SID are mounted. A cable connected to a video processor is electrically connected to the circuit board, and an electrical signal photoelectrically converted by the SID is supplied to the video processor via the cable.

Generally, metal members such as gold, silver, and copper are used for wiring lands and wires provided around the light receiving surface of the SID to improve electrical conductivity. ing. These metal members strongly reflect light because their surfaces are smooth. For this reason, a part of the incident light that has entered the observation optical system causes irregular reflection on these metal members disposed around the light receiving surface of the SID other than the light receiving surface, and the reflected light enters the light receiving surface of the SID. In some cases, the quality of the observed image was impaired due to flare or ghost.

In order to solve the above problem, Japanese Patent Publication No. 6-60
No. 972 discloses that the SI
A light-shielding mask that has been subjected to anti-reflection processing is provided to block light incident on portions other than the light receiving surface of D, and light incident on portions other than the light receiving surface of the SID enters the light receiving surface and causes flare and ghost. The figure shows an imaging device that prevents this.

[0006]

However, in recent years, as endoscopes have become smaller and smaller in diameter, the mounting method of SID chips has been replaced by the conventional wire bonding method, and TA
B, face-down bonding such as flip chip bonding has become mainstream. Therefore, FIG.
As shown in FIG.
The distance between the light receiving area 101a of the ID chip 101 and the cover glass 103 is smaller than before. Further, the distance a1 from the light receiving surface 101a of the SID chip 101 to the package end surface 102 shown in FIG.
Since the outer dimensions of the SID chip 101 and the dimensions after packaging are substantially the same,
From the light receiving surface 101a of the chip 101 to the package end surface 1
The distance a2 to 02 has been greatly reduced.

As a result, as shown in FIG. 16A, the grasping forceps 1 protruding from the distal end surface 105a of the endoscope 105.
When high-intensity light, which has not been a problem until now and is generated by reflecting illumination light emitted from the illumination window 105b at 06 or the like, enters the observation window 105c, as shown in FIG. The high-intensity light beam reflected by the grasping forceps 106 is reflected on the side surface of the cover glass 108b, and
It is impossible to prevent the light from entering the light receiving surface 101a of the chip 101. As a result, the flare 1 is displayed on the endoscope image 111 displayed on the monitor 110 as shown in FIG.
12 and ghosts, etc., had an adverse effect on the endoscope image.

[0008] As shown in FIG.
01 from the light receiving surface 101a to the bonding pad 109a.
Between the light receiving surface 101a and the distance b2 from the light receiving surface 101a to the bonding pad 109b, for example, b1> b2
Opening 107a of the light-shielding mask 107
When the size of the light receiving surface 101a is set to be the same as the size of the light receiving surface 101a, the bonding pad 109a disposed on the side of the distance b1 which is relatively far from the light receiving surface 101a.
While the incident light as shown by the broken line that has entered the observation optical system 113 does not arrive, the incident light as shown by the solid line arrives at the bonding pad 109b disposed on the distance b2 side close to the light receiving surface 101a. Resulting in.

That is, since the distance from the light receiving surface of the SID chip to the bonding pad is reduced, incident light impinges on the bonding pad 109b, and irregular reflection occurs on the surface of the bonding pad 109ba and the thin metal wire 114, and the reflected light Are incident on the light receiving surface 101a of the SID chip 101 and cause flare, ghost, and the like generated in the endoscope image.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image pickup apparatus in which external light is prevented from entering around a light receiving surface of a solid-state image pickup device.

[0011]

According to the present invention, there is provided an imaging apparatus comprising: an observation optical system including a plurality of optical lenses; a solid-state imaging device having an imaging surface disposed at a focal position of the observation optical system; A light-transmissive covering member for covering an imaging surface of the element, a circuit wiring board connected to the solid-state imaging element, the solid-state imaging element, or a signal transmission cable connected to the circuit wiring board; and the solid-state imaging element And a light shielding mask having an opening eccentric in a predetermined direction with respect to the optical axis of the observation optical system.

According to this structure, the opening of the light-shielding mask is disposed eccentrically in a desired direction with respect to the optical axis of the observation optical system, so that external light to the periphery of the imaging surface of the solid-state imaging device can be obtained. Is blocked. As a result, an endoscope image with good image quality is obtained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to a first embodiment of the present invention, FIG. 1 is an explanatory diagram showing a schematic configuration of an endoscope device, FIG. 2 is a front view for explaining a configuration of an imaging device, and FIG. FIG. 4 is a side view for explaining the configuration, FIG. 4 is an explanatory diagram showing the positional relationship between the light shielding mask and the light receiving surface, and FIG. 5 is a diagram for explaining the operation of the light shielding mask of the imaging device.

As shown in FIG. 1, an electronic endoscope 1 equipped with an imaging device according to a first embodiment of the present invention has an elongated insertion portion 2 that can be inserted into a body cavity or the like, for example. A rigid tip portion 3, a bending portion 4 that connects a plurality of bending pieces and can be bent in the vertical and horizontal directions, and a flexible tube portion 5 having flexibility are connected to each other.

An operation portion 6 serving also as a grip portion is provided at the proximal end of the insertion portion 2. A universal cord 7 in which a signal cable, a light guide fiber, and the like are inserted from the side of the operation portion 6 is provided. Is extended. At the end of the universal cord 7, a connector 8 is provided.
A unit (hereinafter referred to as CCU) 9 and the electronic endoscope 1 are detachably connected.

Although not shown, the CCU 9 has a built-in light source device for supplying illumination light to the electronic endoscope 1. The illumination light output from the light source device is connected to the connector 8, the universal cord 7, and the The light is transmitted to the distal end portion 3 by a light guide fiber bundle (not shown) inserted through the insertion section 2 to irradiate the subject.

The CCU 9 has a signal cable 10
Is connected to the monitor 11 via a CCD. The electrical signal of the subject, which is provided in the distal end portion 3 and photoelectrically converted by a solid-state imaging device (hereinafter abbreviated as SID) provided in an imaging device described later, is subjected to signal processing. Then, the image is displayed on the screen of the monitor 11 as an endoscope image.

As shown in FIGS. 2 and 3, the image pickup device 20 disposed in the distal end portion 3 is an objective lens serving as an observation optical system in which a plurality of optical lenses are disposed on a lens frame 21a. Unit 21 and the objective lens unit 21
In which an imaging surface 22a serving as a light receiving surface is arranged at the focal position of
D22, and cover glasses 23 and 24 which are light-transmitting covering members disposed on the front surface of the imaging surface 22a of the SID 22.
And a circuit wiring board 25 connected to the SID 22;
A plurality of signal lines 26a are interpolated and these signal lines 26a are connected to the SID 22 or the circuit wiring board 25, respectively, and a signal transmission cable 26, for example, a cover on the side of the objective lens unit 21 from the imaging surface 22a of the SID 22 A light-shielding mask 2 made of a metal plate which is bonded and fixed to the fixing frame 30 with an adhesive such as epoxy resin so that the opening 27a is positioned on the front surface of the glass 23, and whose surface has been subjected to an antireflection treatment.
7 mainly.

The SID 22 and the cover glasses 23, 24
Is integrally formed as an assembly with a transparent adhesive, and this assembly is integrally fixed to the fixed frame 30 via an adhesive 31. The lead 22b protruding from the side opposite to the imaging surface of the SID 22 is used to connect the assembly to the fixed frame 3.
After fixing to 0, it is cut to a predetermined length.

As shown in FIG. 4, the opening 27a of the light-shielding mask 27 is provided on the side of the cover glass where the illumination light emitted toward the subject is reflected by the grasping forceps projecting from the end surface of the endoscope. In order to prevent the light from being reflected on the imaging surface and entering the imaging surface, only the imaging surface 22 on the part B side opposite to the side where the forceps channels are arranged as shown in the figure.
The SID 22 is formed so as to be misaligned with respect to the imaging surface 22a of the SID 22 so that a becomes narrow. For this reason, when the assembly is integrated into the fixed frame 30, the opening 27 a of the light shielding mask 27 is arranged in a positional relationship eccentric with respect to the optical axis center of the objective lens unit 21. It should be noted that there is no harmful reflected light that passes through the region on the opposite side (forceps channel side) from the part B side and enters the imaging surface 22a.

On the circuit wiring board 25, for example, a signal processing IC connected by face-down bonding
Peripheral circuit components 29 such as a signal processing unit 28 and a capacitor (not shown) sealed with an insulating resin are mounted.

The signal line 26a branched from the signal transmission cable 26 is stripped to a required length and then connected to a connection land 25a provided on the circuit wiring board 25 or a lead 22b projecting from the SID 22. Each is connected. The shielded wires of the signal line 26a are bundled together near the cable branch portion of the signal transmission cable 26 to form a shielded wire binding portion 26b.

On the side surface of the assembly in which the SID 22, the fixed frame 30, the cover glasses 23, 24, and the like are integrally assembled, YAG laser light is shielded from light such as aluminum or stainless steel. The tape 32 is stuck. Further, while the protective tube 33 is placed on the outer peripheral side of the YAG light shielding tape 32, an adhesive 34 is filled in the inside of the YAG light shielding tape 32 and cured to form an imaging unit unit 35. The imaging unit 35 and the objective lens unit 21 are integrally fixed with an adhesive 36 to constitute the imaging device 20.

The operation of the imaging device 20 configured as described above will be described. As shown in FIG. 4, the position of the opening 27a of the light-shielding mask 27 and the position of the imaging surface 22a of the SID 22 are displaced, so that the illumination light emitted toward the subject projects from the distal end surface of the endoscope. Figure 5 reflected by grasping forceps
Is reflected by the light-shielding mask 27, and is reflected by the side surfaces of the cover glasses 23 and 24 and does not enter the imaging surface 22a.

As described above, the opening of the light-shielding mask is positioned so that the imaging surface on the side opposite to the side on which the forceps channel provided on the endoscope is arranged becomes narrower. Due to the misalignment, the central axis of the objective lens unit and the opening of the light-shielding mask have an eccentric positional relationship, and illumination reflected on a treatment tool such as forceps protruding from the distal end surface of the endoscope. Light can be prevented from being reflected on the side surface of the cover glass and incident on the imaging surface of the SID. As a result, an easy-to-view endoscope image free of flare and ghost due to light reflected on the treatment tool can be obtained.

In addition, since the opening of the light-shielding mask is simply formed so that the opening on the imaging surface side on which flare and ghost occur is narrowed, a new method is required to eliminate flare and ghost. In addition, since there is no need to review the lens system design or the electrical processing, the design man-hours can be minimized and flare ghost countermeasures can be achieved at low cost.

When an assembly having a solid-state image sensor is attached to a fixed frame to which a light-shielding mask is attached,
Since the alignment can be performed while checking the position of the side, the conventional operation can be performed without hindering the assembling operation and without using any special jigs and tools.

FIG. 6 is an explanatory diagram showing the configuration near the SID of the imaging apparatus according to the second embodiment of the present invention. As shown in the figure, when the distance A2 from the bonding pad 41b side to the imaging surface 22a is shorter than the distance A1 from the bonding pad 41a side to the imaging surface 22a, the imaging surface 22
bonding pad 41b arranged in the peripheral portion of a
In addition, the incident light reaches the thin metal wire 42 connected to the bonding pad 41b, and the light irregularly reflected by the bonding pad 41b and the thin metal wire 42 easily enters the imaging surface 22a of the SID 22. In order to prevent this, in this embodiment, the opening 2 of the light shielding mask 27 on the distance A2 side is used.
7a is eccentrically formed so as to be located inside the imaging surface 22a of the SID 22. Reference numeral 43 denotes a sealing resin, and reference numeral 44 denotes a ceramic base.

As described above, when the distance from the bonding pad to the light receiving surface is short, the opening of the light-shielding mask on the side where the distance to the light receiving surface is short is formed so as to be located inside the imaging surface of the SID. By reducing the width, light incident on the bonding pads and the fine metal wires arranged in the peripheral portion of the imaging surface can be blocked. This eliminates the problem of the endoscope image caused by flare or ghost generated when light reflected on the bonding pad or the thin metal wire is incident on the light receiving surface.

In order to secure the maximum image height on the light-shielding mask 27, the chamfered portion 27b of the opening of the light-shielded mask provided inside the imaging surface of the SID is formed smaller than the normal chamfered portion 27c. As a result, it is possible to prevent blurring of the subject image.

Hereinafter, the same members as those of the above embodiment are denoted by the same reference numerals, and description thereof will be omitted. Incidentally, as shown in FIG. 7 which is a cross-sectional view taken along the line CC of FIG. 2, in the present embodiment, the protective coat 51 made of an insulating resin such as epoxy or phenol.
Is applied so as to cover the shield wire binding portion 26b and the conductor portion 52 that may be short-circuited.

The protective solder resist 5 made of ink, ceramic, or the like, which is generally applied to protect the conductor 52 provided on the circuit wiring board 25, is used.
If the conductor portion 52 is exposed or the proper coating thickness of the solder resist 53 is not ensured due to the displacement of the conductor 3 or the printing displacement of the conductor portion 52, the circuit wiring board 25 and the signal transmission cable 26 After the connection, the conductor 5
This is to prevent a short circuit between the wire 2 and the shield wire binding portion 26b.

As described above, by providing a protective coat on the conductor portion on the circuit wiring board that may be short-circuited with the shield wire binding portion, for example, when the curved portion of the endoscope is bent, the shield wire binding portion is provided. And the conductor part is suppressed from being exposed by the stress generated in the circuit wiring board,
It is possible to reliably prevent a malfunction of the image pickup apparatus caused by a short circuit between the conductor portion and the shield wire binding portion.

As shown in FIGS. 8 and 9, in the present embodiment, the YAG light shielding tape 32 shown in FIG. 3 is provided so as to extend to the distal end surface 26c of the signal transmission cable 26. However, at this time, in order to avoid a short circuit between the YAG light shielding tape 32 and another metal member,
The YA between the SID 22 portion and the tip end surface 26c
An insulating tape 55 is arranged on the inner layer of the G light shielding tape 32.

As described above, by providing the YAG light-shielding tape so as to extend to the distal end surface of the signal transmission cable, a good image can be obtained by shielding the YAG laser light incident from other than the optical path of the objective lens unit. .

In the present embodiment, the YAG light shielding tape 32 is extended to the front end surface 26c. However, if it is possible to shield the YAG laser light from other than the optical path of the objective lens unit 21, the SID 22 It is sufficient that the insulating tape 55 extends from the end to an arbitrary position between the tip surface 26c and the tip surface 26c.
It goes without saying that the AG light-shielding tape 32 is provided so as to extend to the tip end surface 26c side longer than the AG light shielding tape 32.

As shown in FIG. 10, in the present embodiment, the circuit wiring board 25 is provided with a channel tube and an illumination window 62 communicating with the opening 61 of the treatment instrument insertion channel provided in the electronic endoscope 1. It is arranged on the empty space side behind the observation window 63 in which no built-in component such as a light guide fiber bundle for illumination facing the camera is provided.

Further, as shown in FIG. 11B, the width of the circuit wiring board 25 is formed larger than the outer dimensions of the fixed frame 30. That is, as shown in FIG. 11B, instead of forming the fixed frame 30 to have substantially the same external dimensions as shown in FIG. 11A, the fixed frame 30 can be arranged in the empty space shown in FIG. The width dimension is formed large. As a result, the longitudinal dimension of the circuit wiring board 25 is reduced to B1.
Only short.

By arranging the circuit wiring board on the free space side of the endoscope in such a manner that the outer dimensions thereof are formed as large as possible with respect to the free space, as shown in FIG. Unnecessary space such as a portion D surrounded by an ellipse on the circuit wiring board can be omitted, and the length of the circuit wiring board in the longitudinal direction can be shortened to shorten the rigid length of the imaging device.

By the way, as shown in FIG. 12, in the present embodiment, it is specified that the sagging surface 66 of the diaphragm member 65 arranged in the objective lens unit 21 is arranged to face the subject.

Thus, the objective lens unit 21
Can be prevented from being generated due to interference caused by the light incident on the surface being reflected by the sagging surface. In addition,
An identification mark may be provided on the sagging surface 66 side of the aperture member 65 so that the sagging surface 66 can be easily recognized.

By the way, as shown by the solid line in FIG. 13, the conventional cover glass 71 has a substantially perfect circular shape. For this reason, at the time of assembling the imaging unit, the cover glass 71 was bonded while confirming the center position using a device such as a measuring microscope. For this reason, the operation requires skill, and the dimensional accuracy varies depending on the operator.

In this embodiment, the cover glass 72 is formed in a substantially octagonal shape as shown by a two-dot chain line in FIG.
A linear portion was provided around the cover glass 72.

As described above, since the linear portion is formed around the cover glass, the center position is confirmed with a measuring microscope or the like by making the linear portion correspond to the jig and tool so that the linear portion becomes the reference plane. As a result, the assembling can be easily performed without performing the above operation, so that the operation time can be greatly reduced, and the accuracy can be improved and stabilized.

As shown in the figure, the substantially octagonal cover glass 72 has a larger bonding area than the perfect circular cover glass 71, so the bonding strength is increased and the reliability of the fixing strength is improved. Can be done.

It should be noted that the present invention is not limited to only the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

[Appendix] According to the above-described embodiment of the present invention, the following configuration can be obtained.

(1) An observation optical system, a solid-state imaging device having an imaging surface arranged at a focal position of the observation optical system, a light-transmissive covering member for covering the imaging surface of the solid-state imaging device, and the solid-state imaging device A circuit wiring board connected to the element, the solid-state imaging device, or a signal transmission cable connected to the circuit wiring board; and the observation optical system disposed on the observation optical system side from an imaging surface of the solid-state imaging device. A light-shielding mask having an opening eccentric in a predetermined direction with respect to the optical axis of the imaging device.

(2) An image pickup device provided at the distal end of an endoscope having a treatment instrument channel, comprising: an observation optical system;
A solid-state imaging device having an imaging surface arranged at a focal position of the observation optical system; a light-transmissive covering member for covering the imaging surface of the solid-state imaging device; a circuit wiring board connected to the solid-state imaging device; An image sensor, or a signal transmission cable connected to a circuit wiring board, and disposed on the observation optical system side from an imaging surface of the solid-state image sensor, and an optical axis of the endoscope with respect to an optical axis of the observation optical system. A light-shielding mask having an opening eccentric to the treatment instrument channel side.

Since the opening of the light-shielding mask is eccentrically provided in consideration of the treatment tool insertion channel provided in the endoscope, high-brightness light reflected by forceps or the like is solid-state imaging. The light can be blocked from entering the imaging surface of the element.

(3) An image pickup device provided at the distal end of an endoscope having a treatment instrument channel, comprising: an observation optical system;
A solid-state imaging device having an imaging surface arranged at a focal position of the observation optical system; a light-transmissive covering member for covering the imaging surface of the solid-state imaging device; a circuit wiring board connected to the solid-state imaging device; An image pickup element, or a signal transmission cable connected to a circuit wiring board, and a base end side of the observation optical system, and a tip end side of an imaging surface of the solid-state image pickup element, and An imaging device comprising: a light-shielding mask having an opening eccentric to the treatment instrument channel side of the endoscope with respect to the optical axis.

(4) An imaging device provided at the distal end of an endoscope having a treatment instrument channel, wherein an observation optical system;
A solid-state imaging device having an imaging surface arranged at a focal position of the observation optical system; a light-transmissive covering member for covering the imaging surface of the solid-state imaging device; a circuit wiring board connected to the solid-state imaging device; An image pickup device, or a signal transmission cable connected to a circuit wiring board, and disposed on the observation optical system side from an image pickup surface of the solid-state image pickup device, and eccentric with respect to an optical axis of the observation optical system; An imaging device comprising: a light-shielding mask formed such that an opening end on a bonding pad side close to an imaging surface of an imaging element is positioned inside the imaging surface.

Thus, even if the bonding pad disposed on the outer peripheral portion of the imaging surface is close to the imaging surface, the light of the observation optical system is set so that the opening end of the light shielding mask is located inside the imaging surface. Since it is eccentric with respect to the axis, it is possible to prevent light from being incident on a bonding pad or the like arranged around the imaging surface.

(5) The imaging apparatus according to any one of supplementary notes 1 to 4, wherein the light-shielding mask is a metal plate subjected to an antireflection treatment.

[0055]

As described above, according to the present invention, it is possible to provide an image pickup apparatus in which external light is prevented from entering around the light receiving surface of the solid-state image pickup device.

[Brief description of the drawings]

FIGS. 1 to 5 relate to a first embodiment of the present invention, and FIG. 1 is an explanatory diagram showing a schematic configuration of an endoscope apparatus.

FIG. 2 is a front view illustrating a configuration of an imaging device.

FIG. 3 is a side view illustrating a configuration of an imaging device.

FIG. 4 is an explanatory diagram showing a positional relationship between a light shielding mask and a light receiving surface.

FIG. 5 is a diagram illustrating an operation of a light-shielding mask of the imaging apparatus.

FIG. 6 is an explanatory diagram showing a configuration near an SID of an imaging device according to a second embodiment of the present invention;

FIG. 7 is a view for explaining a protective coat covering a conductor provided on a circuit wiring board;

8 and 9 are diagrams illustrating an example of arrangement of a YAG light-shielding tape, and FIG. 8 is a side view illustrating a configuration of an imaging device in which the light-shielding tape is arranged.

FIG. 9 is a front view illustrating the configuration of an imaging device in which a light shielding tape is arranged.

FIGS. 10 and 11 are diagrams illustrating a configuration example of a circuit wiring board, and FIG. 10 is an explanatory diagram illustrating an arrangement position of the circuit wiring board;

FIG. 11 is a diagram comparing the sizes of circuit wiring boards;

FIG. 12 is a diagram illustrating an arrangement position of a diaphragm member arranged in the objective lens unit.

FIG. 13 is an explanatory diagram showing an example of the shape of a cover glass.

14 to 17 relate to a conventional example, and FIG.
Is an explanatory diagram showing an SID package by a wire bonding method

FIG. 15: SI by face-down bonding method
Explanatory drawing showing D package

FIG. 16 is an explanatory diagram showing a use state of the endoscope and a failure example.

FIG. 17 is an explanatory diagram showing a relationship between a distance from a light receiving surface of an SID chip to a bonding pad and an incident light beam.

[Explanation of symbols]

 Reference Signs List 20 imaging device 21 objective lens unit 22 SID 23, 24 cover glass 25 circuit wiring board 26 signal transmission cable 27 light-shielding mask

Claims (1)

[Claims] 1. An observation optical system including a plurality of optical lenses, a solid-state imaging device having an imaging surface disposed at a focal position of the observation optical system, and a light-transmitting material covering the imaging surface of the solid-state imaging device. A covering member; a circuit wiring board connected to the solid-state imaging device; a signal transmission cable connected to the solid-state imaging device or the circuit wiring substrate; and a signal transmission cable connected to the observation optical system side from an imaging surface of the solid-state imaging device. And a light-shielding mask having an opening decentered in a predetermined direction with respect to the optical axis of the observation optical system.