Endoscopic imaging device and endoscope

Abstract

To provide an endoscope imaging apparatus and an endoscope in each of which breakage of a circuit board and disconnection of the circuit board are prevented.SOLUTION: An endoscope imaging apparatus acquiring an image of an observation object is provided, including; a lens barrel inside which an imaging lens is arranged; an imaging device which receives light passing through the imaging lens and performs photoelectric conversion on the received light; a circuit board to which the imaging device is electrically connected; and a signal cable electrically connected to the circuit board. A connection pad to which the signal cable is electrically connected is arranged on one of the surfaces of the circuit board, and a metal layer is arranged on the other surface that is the opposite side of the one surface of the circuit board. In viewing the circuit board from one surface side or the other surface side, the metal layer is overlapped with the connection pad and is arranged in a region larger than the connection pad.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to an endoscope imaging device and an endoscope for acquiring an image of an observation target, and particularly to an endoscope imaging device and an endoscope in which an imaging element is electrically connected to a circuit board and a signal cable is electrically connected to the circuit board.

Background Art

[0002] In recent years, diagnosis and the like using an endoscope system including an endoscope light source device, an endoscope (endoscope scope), and a processor device have been widely performed. It has an insertion portion that is inserted into the body of a subject, and illumination light from an endoscope light source device is irradiated onto an observation target through the insertion portion. The endoscope images the observation target irradiated with the illumination light by an imaging element to generate an image signal. The processor device performs image processing on the image signal generated by the endoscope to generate an observation image for display on a monitor. The imaging element is electrically connected to a signal cable via a circuit board composed of a flexible wiring board or the like, and the signal cable is electrically connected to the processor device.

[0003] For example, Patent Document 1 describes an endoscope having an imaging module. The imaging module includes an electric cable, an imaging element, and a flexible wiring board. The flexible wiring board has an element mounting portion for mounting the imaging element, and a rear piece portion that is bent at a bending portion only at one end of both ends in the length direction of the element mounting portion and extends to the side opposite to the imaging element. The element mounting portion has a mounting surface that is a surface intersecting the axial direction of the tip of the electric cable and on which the imaging element is mounted. The wiring of the flexible wiring board is connected to the electric cable at the rear piece portion through the bending portion from the mounting surface. A conductor connection portion is formed on the rear piece portion. The conductor connection portion is formed by soldering an internal conductor to a conductor terminal portion.

[0004] Further, for example, Patent Document 2 describes an endoscope having a scope in which a rigid portion is provided at the tip of a long flexible soft portion, and an imaging unit housed in the rigid portion and having an image sensor. A flexible substrate is conductively connected to the back surface of the image sensor via pads. The flexible substrate is disposed between the image sensor and the transmission cable and relays between them. For example, a circuit pattern in which a plurality of linear conductors are pattern-printed is formed on the flexible substrate. The flexible substrate conductively connects each electric wire provided on the transmission cable to this circuit pattern. Thereby, the image sensor is connected to the transmission cable via the flexible substrate. Further, the flexible substrate is bent and formed in an L shape by a sensor connection portion parallel to the back surface of the image sensor and a cable connection portion perpendicular to the back surface. The front surface of the sensor connection portion of the flexible substrate is conductively connected to a pad provided on the back surface of the image sensor. The cable connection portion has a plurality of terminal portions exposed on the upper surface, which are conductively connected to each electric wire of the transmission cable.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a signal cable is connected to a circuit board using solder or the like, the circuit board may become partially rigid at the connection point by the solder. In the endoscopes of Patent Document 1 and Patent Document 2 described above, an electric cable or a transmission cable is connected to a flexible wiring board or a flexible substrate by solder. In this case, since the connection point by solder becomes partially rigid, the flexible wiring board or the flexible substrate may be broken, such as being folded, at the connection point by solder. As a result, the wiring such as the signal lines of the flexible wiring board and the flexible substrate may be disconnected. An object of the present invention is to provide an endoscope imaging device and an endoscope that prevent damage to a circuit board and disconnection of the circuit board.

Means for Solving the Problems

[0007] To achieve the above object, an aspect of the present invention is an endoscope imaging device that acquires an image of an observation target, including a lens barrel provided with an imaging lens inside, an imaging element that receives light that has passed through the imaging lens and performs photoelectric conversion, a circuit board to which the imaging element is electrically connected, and a signal cable electrically connected to the circuit board. A connection pad is provided on one surface of the circuit board to which the signal cable is electrically connected, and a metal layer is provided on the other surface opposite to one surface of the circuit board. When the circuit board is viewed from one surface side or the other surface side, the metal layer overlaps the connection pad and is provided in a range wider than the connection pad. The present invention provides an endoscope imaging device.

[0008] Signal lines are provided on one surface of the circuit board, connection members are provided on the other surface of the circuit board, the imaging element is electrically connected to the connection members and is provided on the other surface, and it is preferable that the connection members are electrically connected to the signal lines in a region of one surface on the opposite side of the surface where the imaging element is provided. The circuit board is provided with a recess connected by a connecting portion on a side surface in the width direction orthogonal to the extending direction of the circuit board, and it is preferable that the connecting portion is inside the circuit board rather than on the side surface. The circuit board has a front end portion where the imaging element is provided, a curved portion, an inclined portion, and a rear end portion where the connection pad is provided in this order, and it is preferable that electronic components for driving the imaging element are provided on one surface of the inclined portion of the circuit board. The optical axis of the imaging lens is preferably perpendicular to the light receiving surface of the imaging element. The optical axis of the imaging lens is preferably parallel to the light receiving surface of the imaging element. The metal layer is preferably electrically connected to the ground. Another aspect of the present invention provides an endoscope having the endoscope imaging device of the present invention.

Advantages of the Invention

[0009] According to the present invention, an endoscope imaging device and an endoscope that prevent damage to the circuit board and disconnection of the circuit board can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0011] Hereinafter, based on the preferred embodiments shown in the accompanying drawings, the endoscope imaging apparatus and endoscope of the present invention will be described in detail. Note that the drawings described below are illustrative for explaining the present invention, and the present invention is not limited to the drawings shown below. In the following description, “parallel”, “perpendicular”, “orthogonal”, etc. include the error ranges generally acceptable in the corresponding technical field.

[0012] 〔Endoscope System〕 The endoscope system irradiates illumination light (not shown) to an observation site such as inside the body of a subject to be observed, images the observation site, generates a display image of the observation site based on the image signal obtained by imaging, and displays the display image. FIG. 1 is a schematic diagram showing an example of an endoscope system according to an embodiment of the present invention. The endoscope system 10 includes an endoscope 12, a light source device 14, and a processor device 16. The endoscope system 10 has a configuration similar to that of a general endoscope except for the part of the endoscope imaging device 20 (see FIG. 2) of the endoscope 12 described later.

[0013] The endoscope 12 has an endoscope imaging device 20 (see FIG. 2). Further, although not shown in detail, the endoscope 12 has an insertion portion inserted into the subject, an operation portion connected to the insertion portion, and a universal cord extending from the operation portion. The insertion portion is composed of a distal end portion, a bending portion connected to the distal end portion, and a flexible portion connecting the bending portion and the operation portion. The endoscope imaging device 20 (see FIG. 2) will be described later.

[0014] At the distal end portion of the endoscope 12, there is provided an endoscope imaging device 20 (see FIG. 2) having an illumination optical system for emitting illumination light for illuminating the observation site, or an imaging element and an imaging optical system for imaging the observation site. The bending portion is configured to be bendable in a direction orthogonal to the longitudinal axis of the insertion portion, and the bending operation of the bending portion is operated at the operation portion. Further, the flexible portion is configured to be relatively flexible so as to be deformable following the shape of the insertion path of the insertion portion.

[0015] The operation unit is provided with buttons for operating the imaging operation of the endoscope imaging device 20 (see Fig. 2) at the tip, or knobs for operating the bending operation of the bending section. Further, the operation unit is provided with an introduction port into which a treatment tool such as an electric scalpel is introduced, and inside the insertion section, there is provided a treatment tool channel that reaches from the introduction port to the tip and through which a treatment tool such as forceps is inserted.

[0016] A connector is provided at the end of the universal cord, and the endoscope 12 is connected via the connector to a light source device 14 that generates illumination light emitted from the illumination optical system at the tip, and a processor device 16 that processes the video signal acquired by the endoscope imaging device 20 (see Fig. 2) at the tip.

[0017] The processor device 16 processes the input video signal to generate video data of the observation site, and displays the generated video data on a monitor (not shown) or records it on a storage medium such as a hard disk. Note that the processor device 16 may be constituted by a processor such as a personal computer.

[0018] The light source device 14 generates illumination light such as white light composed of three primary colors of light, red light (R), green light (G), and blue light (B), or specific wavelength light, etc., in order to image the observation target site in the body cavity by the endoscope imaging device 20 (see Fig. 2) of the endoscope 12 and acquire an image signal of the observation target, supplies it to the endoscope 12, propagates it through a light guide or the like inside the endoscope 12, and emits it from the illumination optical system at the tip of the insertion section of the endoscope 12 to illuminate the observation target site in the body cavity.

[0019] A light guide or a group of electric wires (signal cables) is accommodated inside the insertion section, the operation unit, and the universal cord. The illumination light generated by the light source device 14 is guided to the illumination optical system at the tip through the light guide, and at least one of the signal and power is transmitted between the endoscope imaging device 20 (see Fig. 2) at the tip and the processor device 16 through the group of electric wires. In addition, a treatment tool channel (not shown) tip and an illumination optical system (not shown) that emits illumination light guided from the light source device 14 via a light guide are accommodated and fixed in an accommodation hole (not shown) formed at the tip of the endoscope system 10. For example, at the tip of the endoscope system 10, the endoscope imaging device 20 is fixed with the light receiving surface 29a (see FIG. 4) of the imaging element 29 (see FIG. 4) being substantially perpendicular to the longitudinal axis of the insertion portion.

[0020] In addition, the endoscope system 10 may further include a water supply tank that stores cleaning water or the like, a suction pump that suctions aspirated matter in the body cavity (including supplied cleaning water or the like), and the like. Furthermore, it may include a supply pump or the like that supplies cleaning water in the water supply tank or gas such as external air to a pipeline (not shown) inside the endoscope.

[0021] 〔Endoscope Imaging Device〕 FIG. 2 is a schematic perspective view showing an endoscope imaging device according to an embodiment of the present invention, FIG. 3 is a schematic partial cross-sectional perspective view showing an endoscope imaging device according to an embodiment of the present invention, FIG. 4 is a schematic plan view showing an endoscope imaging device according to an embodiment of the present invention, and FIG. 5 is a schematic side view showing an endoscope imaging device according to an embodiment of the present invention. The endoscope imaging device 20 shown in FIG. 2 is mounted at the tip of the endoscope 12 of the endoscope system 10 shown in FIG. 1. The endoscope imaging device 20 is also referred to as a camera head.

[0022] The endoscope imaging device 20 shown in FIGS. 2 to 5 acquires an image of an observation target. The endoscope imaging device 20 includes an imaging lens 23 (see FIG. 3), a lens barrel 22 that holds the imaging lens 23, a holder 24, a filter 26, a mask 27, a cover glass 28, an imaging element 29, a circuit board 30, and a signal cable 32. In addition, the endoscope imaging device 20 has an anchor 34.

[0023] The lens barrel 22 is a cylindrical member, and although not shown in the figure, it holds one or more imaging lenses 23 inside (see Fig. 3, reference numeral 22a). The lens barrel 22 holds the imaging lens 23 such that the optical axis C of the imaging lens 23 is perpendicular to the light receiving surface 29a of the image sensor 29. The endoscope imaging device 20 has, for example, four imaging lenses 23, although not shown in detail here. Here, as shown in Fig. 2, the direction parallel to the optical axis C is defined as the X direction. Of the two directions orthogonal to the optical axis C, one is defined as the Y direction and the other as the Z direction. The Y direction corresponds to the width direction of the endoscope imaging device 20. The Z direction corresponds to the height direction of the endoscope imaging device 20 and corresponds to the vertical direction described later.

[0024] The imaging lens 23 is an optical element that forms an image of the light incident on the imaging lens 23 on the light receiving surface 29a of the image sensor 29 (see Fig. 4). The imaging lens 23 is held by the lens barrel 22. The configurations of the imaging lens 23 and the lens barrel 22 are not particularly limited. For example, the configuration may have one imaging lens 23, or may have two, three, or five or more imaging lenses 23. Also, each imaging lens 23 may be a convex lens or a concave lens.

[0025] The image sensor 29 is an image sensor that performs imaging by converting the light formed into an image by the imaging lens 23 into an electrical signal by photoelectric conversion. The image sensor 29 is a conventionally known image sensor, and a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor can be used. A cover glass 28 is disposed on the light receiving surface 29a of the image sensor 29, and the cover glass 28 protects the light receiving surface 29a. The image sensor 29 and the cover glass 28 are, for example, integrated, and the cover glass 28 constitutes a part of the image sensor 29. Note that, unless otherwise specified, the positioning of the image sensor 29 also includes the case where the image sensor 29 is positioned using the cover glass 28. Also, the image sensor 29 may have a configuration without the cover glass 28.

[0026] The imaging element 29 is held by the holder 24. The imaging element 29 is electrically connected to the circuit board 30 via, for example, conductive bumps 33 (see FIG. 4). Further, as shown in FIG. 4, the imaging element 29 is mounted on the circuit board 30 such that the light receiving surface 29a is orthogonal to the optical axis C of the imaging lens 23. That is, the optical axis C of the imaging lens is perpendicular to the light receiving surface 29a of the imaging element 29. Note that "mounted" means being electrically connected. An underfill layer (not shown) can be provided between the imaging element 29 and the circuit board 30 to firmly connect the imaging element 29 and the circuit board 30.

[0027] The bump 33 is made of a metal or an alloy. More specifically, the bump 33 is made of solder. The bump 33 formed of solder is also referred to as a solder ball. Note that the bump 33 is not limited to solder or the like as long as it can electrically connect the imaging element 29 and the circuit board 30. Further, the imaging element 29 and the circuit board 30 may be electrically connected using an anisotropic conductive film or may be directly electrically connected. In addition, due to the difference in the coefficient of thermal expansion between the imaging element 29 and the circuit board 30, stress is generated in the joint between the imaging element 29 and the circuit board 30, for example, the bump 33, but this stress is relaxed by the underfill layer. The underfill layer firmly connects the imaging element 29 and the circuit board 30, increasing the reliability of the electrical connection and obtaining an endoscope imaging device 20 with high reliability. The underfill agent constituting the underfill layer is not particularly limited, and those used as a sealing resin between the imaging element 29 and the circuit board 30 can be appropriately used. For example, a one-component heat-curable epoxy resin is used as the underfill agent. In this case, after supplying the underfill agent, it is heated and held at a predetermined temperature to form the underfill layer.

[0028] The circuit board 30 is a board on which the imaging element 29 is mounted. In addition to the imaging element 29, for example, electronic components 31 are mounted on the circuit board 30. The electronic components 31 are for driving the imaging element 29 and are not particularly limited, and examples include a voltage regulator, a resistor, and a capacitor. The voltage regulator is a device that stabilizes the voltage to the imaging element 29 and outputs a constant voltage to the imaging element 29. Also, on the surface 30a of the circuit board 30, a plurality of connection terminals 40 for inputting and outputting signals or power to the imaging element 29 and the electronic components 31 are provided. The signal line 32a of the signal cable 32 is electrically connected to the connection terminal 40. In addition to the connection terminal 40, it has a signal line 41, a connection portion 42, etc. as will be described later. Note that the surface 30a of the circuit board 30 corresponds to, for example, one surface of the circuit board 30. Also, the back surface 30g of the circuit board 30 (see FIG. 8) to be described later corresponds to, for example, the other surface. The surface on the opposite side of one surface is the other surface. That is, for example, the surface on the opposite side of the surface 30a of the circuit board 30 is the back surface 30g.

[0029] In the illustrated example, the circuit board 30 has a shape in which, for example, a plate-like member is curved at one location and has a curved portion 30c (see FIGS. 2 and 5). Specifically, the circuit board 30 is bent with respect to an axis extending in the Y direction, which is a direction orthogonal to the optical axis C direction of the imaging lens 23. The tip portion 30b (see FIG. 3) of the circuit board 30 on the tip side of the curved portion 30c extends in the Z direction, and the tip portion 30b is electrically connected to the imaging element 29. The rear end side of the curved portion 30c extends in the optical axis C direction, and the electronic components 31 are mounted on the surface 30a on the rear end 30p side (see FIGS. 7 to 9 to be described later) of the circuit board 30, and connection terminals for electrically connecting to the signal cable 32 are provided. Also, connection pads 30d are provided on the surface 30a of the circuit board 30, and the connection pads 30d are electrically connected to a metal layer 30h (see FIG. 8). The configuration of the circuit board 30 will be described later. The shield conductor 32c of the signal cable 32 is electrically connected to the connection pad 30d by soldering or the like, and the potential of the shield conductor 32c is set to the ground potential. Thereby, the endoscope imaging device 20 has higher noise resistance and can reduce the influence of noise on the imaging element 29. Note that the signal cable 32 is electrically connected to the imaging element 29 as will be described later, and will be described later.

[0030] The circuit board 30 is preferably a flexible board, and is constituted by, for example, a flexible printed board. Further, the circuit board 30 is not limited to curving at one location, and the number of curved locations is appropriately determined according to the configuration of the endoscope imaging device 20. Also, the arrangement of the imaging element 29, electronic components 31, connection terminals, etc. on the circuit board 30 is not particularly limited. Further, as shown in FIG. 5, for example, in the Z direction of the endoscope imaging device 20, that is, in the vertical direction, the curved portion 30c of the circuit board 30 may protrude from the lower end surface 34g of the anchor 34. By protruding the curved portion 30c from the lower end surface 34g of the anchor 34 in this way, the curvature of the curved portion 30c of the circuit board 30 can be increased. That is, the radius of curvature of the curved portion 30c of the circuit board 30 can be decreased. Also, in the circuit board 30, by protruding the curved portion 30c from the lower end surface 34g of the anchor 34, the space below the anchor 34 can be effectively utilized. Note that the lower end surface 34g of the anchor 34 is the lower surface of the bottom portion 34a of the anchor 34.

[0031] The signal cable 32 is connected to the connection terminal 40 on the surface 30a of the circuit board 30, and the imaging element 29 and the signal cable 32 are electrically connected. Light is converted into an electrical signal by the imaging element 29, and this electrical signal is transmitted via the signal cable 32. The signal cable 32 is inserted through the insertion portion, operation portion, universal cord, etc. of the endoscope and is electrically connected to the processor device 16 (see FIG. 1). Note that the signal cable 32 is not particularly limited as long as it has an outer skin 32d that constitutes the outer periphery.

[0032] As shown in FIGS. 2 and 4, for example, the signal cable 32 has a plurality of signal lines 32a, a coating layer 32b that coats each signal line 32a, a shield conductor 32c provided around the entire plurality of signal lines 32a coated with the coating layer 32b, and an outer sheath 32d that coats the shield conductor 32c. As described above, the outer sheath 32d constitutes the outer periphery of the signal cable 32. The coating layer 32b, the shield conductor 32c, and the outer sheath 32d are, for example, cylindrical. Also, the shield conductor 32c of the signal cable 32 is referred to as a shield. The signal cable 32 has, for example, four signal lines 32a. The number of signal lines 32a depends on the configuration of the endoscopic imaging device 20 and is not particularly limited, and may be two, three, or five or more. The signal cable 32 is a multi-core cable in which a plurality of signal lines 32a are bundled, a shield conductor 32c is provided around them, and they are housed in a cylindrical outer sheath 32d.

[0033] FIG. 6 is a schematic perspective view showing an example of a holder of the endoscopic imaging device according to an embodiment of the present invention. The holder 24 shown in FIG. 6 is a member that is connected to the lens barrel 22 and holds the imaging element 29. The holder 24 is a substantially cylindrical member and has a mounting cylinder portion 24a provided with a through hole 24d into which the lens barrel 22 is to be mounted. The lens barrel 22 (see FIG. 2) is fitted into the inside of the through hole 24d to hold the lens barrel 22. The inner surface of the holder 24 and the outer peripheral surface of the lens barrel 22 are, for example, adhesively fixed. As the adhesive for bonding the holder 24 and the lens barrel 22, various known adhesives used in conventional endoscopes can be used. As the adhesive, for example, an epoxy-based adhesive, a silicone-based adhesive, or an acrylic-based adhesive can be used, and the same applies to adhesives for bonding other members together. The lens barrel 22 is adjusted so that the relative position of the lens barrel 22 with respect to the holder 24 in the optical axis C direction of the imaging lens 23 (see FIG. 3) is in focus on the light receiving surface 29a of the imaging element 29, and is adhesively fixed to the holder 24.

[0034] The holder 24 has a polygonal flange portion 24b on the side opposite to the side where the lens barrel 22 of the mounting cylinder portion 24a is attached. On the side of the flange portion 24b opposite to the mounting cylinder portion 24a, there are a pair of regulating members 25. The pair of regulating members 25 are provided opposite to each other. The pair of regulating members 25 have the same shape and size, and are, for example, composed of square flat plates. In the holder 24, a pair of the above-described regulating members 25 are provided opposite to each other on the surface 24c of the flange portion 24b on the side opposite to the mounting cylinder portion 24a. For example, the opposing direction in which the pair of regulating members 25 oppose each other is orthogonal to the optical axis direction of the optical axis C of the imaging lens 23. The opposing direction is, for example, a direction parallel to the Y direction. Note that the optical axis direction of the optical axis C is the extending direction of the optical axis C. Here, the above-described vertical direction is a direction orthogonal to the opposing direction in which the pair of regulating members 25 oppose each other and the optical axis direction.

[0035] The imaging element 29 is held by, for example, a pair of regulating members 25 of the holder 24. Between the surface 24c of the flange portion 24b of the holder 24 and the imaging element 29, as shown in FIGS. 2 and 3, from the side of the flange portion 24b of the holder 24, a filter 26, a mask 27, and a cover glass 28 are arranged in this order. The filter 26, the mask 27, the cover glass 28, and the imaging element 29 have substantially the same shape and substantially the same size in plan view, and are, for example, quadrangular in plan view. The filter 26, the mask 27, and the cover glass 28 are also held by the pair of regulating members 25.

[0036] The filter 26 shown in FIG. 2 suppresses the incidence of flare or the like on the light receiving surface 29a of the imaging element 29. The filter 26 is composed of, for example, glass. The mask 27 regulates a part of the light that has passed through the imaging lens 23, preventing stray light and the like from entering the image sensor 29. The mask 27 is, for example, a plate-like member provided with a circular hole 27a (see FIG. 3) in a region corresponding to the through-hole 24d. When viewing the through-hole 24d from the optical axis direction of the optical axis C of the imaging lens 23, the outer edge of the through-hole 24d is blocked by the mask 27 over the entire circumference. The mask 27 is made of, for example, stainless steel, synthetic resin, brass alloy, or aluminum alloy.

[0037] The filter 26 and the cover glass 28 are in contact with both sides of the mask 27 in the optical axis direction. The mask 27, the filter 26, and the cover glass 28 are adhered using, for example, a photocurable adhesive. When adhering using a photocurable adhesive, it is preferable that the filter 26 and the cover glass 28 in contact with both sides of the mask 27 in the optical axis direction transmit light of the wavelength at which the photocurable adhesive cures. Also, even when the filter 26 or the cover glass 28 is not provided on both sides of the mask 27 in the optical axis direction, it is preferable that the members in contact with both sides of the mask 27 in the optical axis direction transmit light of the wavelength at which the photocurable adhesive cures. Note that transmitting light of the wavelength at which the photocurable adhesive cures means having a transmittance sufficient to allow the photocurable adhesive to be adhered. The photocurable adhesive is, for example, an adhesive that cures by ultraviolet light with a wavelength of about 100 to 400 nm, visible light wavelengths greater than 400 and less than 780 nm, or infrared light with a wavelength of about 780 nm to 1 mm. The photocurable adhesive is, for example, an epoxy resin-based photocurable adhesive, an acrylic resin-based photocurable adhesive, or a silicone-based photocurable adhesive. Also, an adhesive that combines photocuring and thermosetting may be used.

[0038] The anchor 34 shown in FIGS. 2 to 5 holds the signal cable 32 with respect to the holder 24. Also, the mechanical strength of the endoscope imaging device 20 is maintained by the anchor 34. The anchor 34 has, for example, as shown in FIG. 2, a flat bottom portion 34a formed by bending a single plate material, and a holding portion 34d having a flat base material portion 34c continuous with the bottom portion 34a. The holding portion 34d is provided to face in the Y direction and holds the signal cable 32 as will be described later. In the anchor 34, the side of the holding portion 34d is taken as the base end 35a. The base material portion 34c is bent, for example, by caulking so as to follow the outer skin 32d of the signal cable 32. As a result, the signal cable 32 is fixed and held in the holding portion 34d. When the base end 35a of the anchor 34 is viewed in the optical axis direction in a state where the signal cable 32 is fixed to the holding portion 34d, for example, a substantially triangular shape is formed by a pair of holding portions 34d and the bottom portion 34a. This suppresses a load from being applied to the circuit board 30 and suppresses deformation of the circuit board 30.

[0039] Further, the anchor 34 is provided with arm portions 34b extending linearly on the bottom portion 34a. The pair of arm portions 34b face each other. The arm portions 34b are physically separated from the base material portion 34c with a gap 34e on the base end 35a side. This prevents deformation of the arm portion 34b from being transmitted to the holding portion 34d and deformation of the holding portion 34d from being transmitted to the arm portion 34b.

[0040] The facing direction in which the pair of arm portions 34b face each other is the same direction as the facing direction in which the pair of regulating members 25 face each other, and is orthogonal to the optical axis direction of the optical axis C of the imaging lens 23. The facing direction in which the pair of arm portions 34b face each other is, for example, parallel to the Y direction. The interval between the pair of arm portions 34b is appropriately determined according to the arrangement of the regulating members 25 of the holder 24. The pair of arm portions 34b on the tip 35b side of the anchor 34 are fixed with the regulating members 25 of the holder 24 interposed therebetween. The arm portion 34b is fixed to the outer surface 25c (see FIGS. 2 and 6) outside the regulating member 25. The outer surface 25c outside the regulating member 25 is the surface on the opposite side of the inner surface 25f provided with the concave portion 25d (see FIG. 6). By fixing the arm portion 34b to the outer surface 25c on the outside of the restricting member 25, interference of the arm portion 34b is suppressed during positioning of the holder 24 and the imaging element 29, and further, interference with the circuit board 30 is also suppressed. Further, with the configuration in which the arm portion 34b is fixed to the outer surface 25c on the outside of the restricting member 25, the restricting member 25 can be used for positioning the imaging element 29, and the positional accuracy between the imaging element 29 and the imaging lens 23 of the lens barrel 22 can be increased.

[0041] Also, as shown in FIGS. 2 and 5, each arm portion 34b is provided with, for example, a groove 34f at the end on the tip 35b side. For example, solder 37 is supplied to the groove 34f, and the arm portion 34b is fixed to the restricting member 25 of the holder 24. The shape of the groove 34f is not particularly limited. For example, the bottom of the groove 34f is formed of a curve. In this case, the groove 34f is called a U-shaped groove. Also, for example, the bottom of the groove 34f may be formed of a polygon. In this case, the groove 34f is, for example, called a V-shaped groove. Further, it is not limited to the above-described groove 34f, and a configuration in which a through hole (not shown) is provided in the arm portion 34b may be used. The shape of the through hole is not particularly limited, and is, for example, a circle, an ellipse, or a polygon. Note that if the arm portion 34b has a groove 34f or a through hole in the region fixed to the holder 24, specifically, the portion in contact with the outer surface 25c of the restricting member 25, when joining and fixing the arm portion 34b to the holder 24 using solder 37, it is preferable because the joining area can be increased.

[0042] The anchor 34 is formed of, for example, a metal material. The metal material forming the anchor 34 is not particularly limited, but considering workability, availability, strength, etc., stainless steel and copper alloy are preferable as the anchor 34. When fixing the anchor 34 using solder 37, it is preferable to perform a plating process so that the solder 37 easily adheres to the anchor 34.

[0043] By connecting the anchor 34 to the holder 24 and the signal cable 32 respectively, when the signal cable 32 is pulled, etc., the connection point between the connection terminal 40 on the circuit board 30 and the signal line 32a of the signal cable 32 is pulled, preventing the connection between the connection terminal 40 and the signal line 32a from being disconnected.

[0044] The signal cable 32 is fixed to the anchor 34 using, for example, an adhesive or solder (not shown). It is preferable to join the holding portion 34d of the anchor 34 and the shield conductor 32c of the signal cable 32 using solder. By using solder, the potential can be set to the ground potential including the anchor 34, and moreover, the electrical resistance at the joint can be reduced. As a result, the noise resistance becomes higher, and the influence of noise on the imaging element 29 can be made smaller. Also, by using solder, the mechanical strength at the joint can be increased. After joining the circuit board 30 and the signal cable 32 using solder, the endoscope imaging device 20 joins the holding portion 34d of the anchor 34 and the signal cable 32 using solder.

[0045] Here, FIG. 7 is a schematic plan view showing the surface of an example of the circuit board of the endoscope imaging device according to an embodiment of the present invention, and FIG. 8 is a schematic plan view showing the back surface of an example of the circuit board of the endoscope imaging device according to an embodiment of the present invention. FIG. 9 is a schematic side view showing an example of the circuit board of the endoscope imaging device according to an embodiment of the present invention. As shown in FIG. 7, a connection terminal 40, a signal line 41, and a connection portion 42 are provided on the surface 30a of the circuit board 30. The connection terminal 40, the signal line 41, and the connection portion 42 are electrically connected. The connection terminal 40 is electrically connected by the signal cable 32 (see FIG. 2) using solder or the like. For example, the connection terminal 40 to which the signal cable 32 (see FIG. 2) is connected becomes the hardness change point. The signal line 41 is composed of a conductor and relays the connection terminal 40 and the connection portion 42. The electrical signal from the imaging element 29 is transmitted from the connection portion 42 to the connection terminal 40 and then transmitted to the signal cable 32. The connection part 42 is provided in a region 43 on the front surface 30a of the circuit board 30 on the side opposite to the back surface 30g where the imaging element 29 is provided. Further, the connection part 42 extends in the thickness direction of the circuit board 30. The above-mentioned region 43 is at the tip part 30b of the circuit board 30. Also, the connection part 42 is electrically connected to a connection member 44 on the back surface 30g of the circuit board 30. The signal line 41 and the connection member 44 are electrically connected by the connection part 42.

[0046] The connection member 44 electrically connects the imaging element 29 and the circuit board 30. The connection member 44 is provided on the back surface 30g of the circuit board 30. Note that the number of connection terminals 40, the number of signal lines 41, and the number of connection parts 42 are the same as the number of output terminals (not shown) of the imaging element 29 (see FIG. 2).

[0047] The configuration of the connection part 42 is not particularly limited as long as it can electrically connect the signal line 41 and the connection member 44. The connection part 42 is composed of a conductor arranged in the thickness direction of the circuit board 30 and is generally called a via. Examples of the via include a plated through hole, a via hole, or a filled via. The connection member 44 electrically connects to the imaging element 29, and its configuration is not particularly limited. Examples include a connection terminal or a solder ball. When the imaging element 29 is connected to the connection member 44, the connection location of the imaging element 29 becomes a hardness change point.

[0048] As shown in FIG. 7, on the front surface 30a of the circuit board 30, the above-mentioned connection pad 30d is provided on the side opposite to the connection part 42 with respect to the connection terminal 40. As shown in FIG. 8, a metal layer 30h is provided on the back surface 30g of the circuit board 30. The connection pad 30d (see FIG. 7) is electrically connected to the metal layer 30h. Both the connection pad 30d and the metal layer 30h are conductive films. When the circuit board 30 is viewed from the surface 30a (see FIG. 7) side or the back surface 30g (see FIG. 8) side, the metal layer 30h overlaps with the connection pad 30d and is provided in a range wider than the connection pad 30d. The metal layer 30h also has a function of reinforcing the circuit board 30 in terms of strength. By the metal layer 30h, local breakage at the hardness change point can be prevented, and disconnection of wirings such as the signal line 41 of the circuit board 30 can be prevented. Even when the circuit board 30 has a configuration having a curved portion 30c (see FIG. 2), local breakage at the hardness change point can be prevented, and disconnection of wirings such as the signal line 41 of the circuit board 30 can be prevented. Also, when the circuit board 30 is small and thin due to miniaturization of the endoscope imaging device 20, the signal line 41 etc. also need to be thin. In this case, when the circuit board 30 is bent, the circuit board 30 may break or the wiring such as the signal line 41 may be disconnected. However, by providing the metal layer 30h as described above to overlap with the connection pad 30d and in a range wider than the connection pad 30d, breakage such as the circuit board 30 being broken and disconnection of the wiring such as the signal line 41 of the circuit board 30 can be prevented.

[0049] Also, since the metal layer 30h also serves as a noise shield layer, the high-frequency signals input to and output from the imaging element 29 or the electronic component 31 are less likely to be disturbed. Also, the connection pad 30d is also an electrical resistance change point. For example, noise is generated when the imaging element 29 is driven. Even when such noise is generated, the metal layer 30h can prevent leakage of noise generated from the imaging element 29 etc., and can shield noise from the outside of the endoscope imaging device 20. The metal layer 30h is preferably electrically connected to the ground. Thereby, the metal layer 30h becomes the ground potential, the function as a noise shield layer is further enhanced, and the high-frequency signals input to and output from the imaging element 29 or the electronic component 31 are even less likely to be disturbed.

[0050] Here, the ground of the insertion portion (including the sensor) of the endoscope is generally as follows. The ground is a metal part that is connected to the ground alternately via a capacitor or the like. High-frequency currents (noise in the MHz to GHz range) are released to the ground, while leakage currents such as those from an electric scalpel (about several hundred kHz) and direct current are insulated from the ground to prevent electric shock (preventing the formation of a closed circuit between the human body and the ground). Also, this part serves as the potential reference for various locations in the device. By passing the signal line through a location surrounded by the reference potential as much as possible, it can be protected from the influence of other potentials (noise).

[0051] Note that the range where the metal layer 30h is provided is wider than the connection pad 30d. That the metal layer 30h is provided in a range wider than the connection pad 30d means that the area of the metal layer 30h is larger than the area of the connection pad 30d. In this case, it is preferable that the metal layer 30h is about three times the thickness of the circuit board 30 larger than the connection pad 30d. Here, the curved portion 30c of the circuit board 30 is formed by bending the circuit board 30. However, it is easier to bend the circuit board 30 and form the curved portion 30c when there is no metal layer 30h. Therefore, as the upper limit of the range where the metal layer 30h is provided, it is preferable that it is from the rear end 30p of the circuit board 30 (see FIGS. 7 to 9) to the front of the curved portion 30c.

[0052] Here, that the metal layer 30h overlaps the connection pad 30d means that all of the connection pad 30d is within the metal layer 30h. The connection pad 30d, the metal layer 30h, the connection terminal 40, the signal line 41, the connection portion 42, and the connection member 44 of the circuit board 30 are made of, for example, copper, similar to the wiring layer of a flexible printed circuit board. In addition to the above-mentioned copper, the metal layer 30h can also be made of a copper alloy, aluminum, an aluminum alloy, stainless steel, or the like.

[0053] The imaging element 29 is electrically connected to the connection member 44 and is also electrically connected to the circuit board 30, and is provided on the back surface 30g of the circuit board 30. In the region 43 of the front surface 30a, which is on the side opposite to the back surface 30g of the circuit board 30 where the imaging element 29 is provided, the connection member 44 on the back surface 30g of the circuit board 30 is electrically connected to the signal line 41 via the connection portion 42. In this way, the imaging element 29 is electrically connected to the signal line 41. Note that the signal line 41 is provided on the front surface 30a of the circuit board 30 as described above. The connection portion 42 causes a hardness change point to occur in the region 43 of the tip portion 30b described above, but since the curved portion 30c can be avoided, breakage of the circuit board 30 can be prevented. Also, since the signal line 41 and the connection portion 42 can be arranged on the front surface 30a side of the circuit board 30, that is, on the same surface side, two-sided wiring between the front surface 30a and the back surface 30g of the circuit board 30 becomes unnecessary, and the wiring structure of the circuit board 30 can be simplified. In addition, there is no need to provide signal lines or the like on the back surface 30g side of the circuit board 30, mechanical contact of the signal lines or the like of the circuit board 30 can be suppressed, and disconnection of the signal lines of the circuit board 30 can also be prevented. Furthermore, as described above, since two-sided wiring of the circuit board 30 becomes unnecessary, the thickness of the circuit board 30 can be reduced, and the outer diameter of the endoscope imaging device 20 can be decreased.

[0054] The connection pads 30d are provided on the front surface 30a of the circuit board 30, and the metal layer 30h is provided on the back surface 30g of the circuit board 30. However, the metal layer 30h is not limited to being provided on the back surface 30g of the circuit board 30. When the circuit board 30 has a multilayer wiring structure, for example, connection pads 30d are provided on the front surface 30a of the circuit board 30. The metal layer 30h may be provided on the back surface of the circuit board having a multilayer wiring structure, or may be provided on the surface of another layer among the multilayer wiring layers of the circuit board having a multilayer wiring structure where the connection pads 30d are not provided. The other layer is a layer inside the circuit board. The surface of the other layer is any one of the surfaces facing in the stacking direction of the circuit board having a multilayer wiring structure in the other layer. Further, the metal layer 30h may be provided on the surfaces of a plurality of layers including the other above-described layers in which the connection pads 30d are not provided among the multilayer wiring layers. That is, the metal layer 30h may be provided on a plurality of layers among the multilayer wiring layers. The surfaces of the plurality of layers correspond to the surfaces on the opposite side of the surface of the circuit board having the above-described multilayer wiring structure. Similar to the other layers, the surfaces of the plurality of layers are any of the surfaces facing each other in the stacking direction of the circuit board having the multilayer wiring structure. Note that the surface of the other layer of the multilayer wiring layer provided with the metal layer 30h is included in the other surface on the opposite side of one surface, and further, the surfaces of the above-described plurality of layers are also included.

[0055] Depending on the configuration of the imaging element 29, many wirings may be required. In the case of such an imaging element 29, it is necessary to provide wirings on the back surface of the circuit board, and the metal layer 30h may not be provided on the back surface of the circuit board. In this case, it can be provided on the surface of the other above-described layer or the surfaces of a plurality of layers including the other layer. Note that, as described above, in the circuit board having the multilayer wiring structure, by providing the metal layer 30h on the surface of the other layer of the multilayer wiring layer, the effect of preventing the circuit board from breaking, such as local breakage at the above-described hardness change point, can also be obtained. Further, when the metal layer 30h is provided on the surfaces of a plurality of layers including the other above-described layers in which the connection pads 30d are not provided among the multilayer wiring layers, the strength of the circuit board is further increased, and the circuit board is more difficult to break. In addition, when the metal layer 30h is provided on the surfaces of a plurality of layers, since the cross-sectional area increases, the electrical resistance of the metal layer 30h becomes lower, and it becomes easier to further escape noise from the shield conductor 32c of the signal cable 32.

[0056] The circuit board 30 is provided with a recess 45 connected by a connecting portion 46 to a side surface 30e in the width direction Dw orthogonal to the extending direction Ds of the circuit board 30. For example, the recesses 45 are arranged at intervals along the extending direction Ds of the circuit board 30, and the two recesses 45 are connected by the connecting portion 46. The connecting portion 46 between the recesses 45 is inside the circuit board 30 rather than the side surface 30e. Thereby, when the circuit board 30 is separated into individual pieces as described later, the runner portion 48a (see FIG. 10) in the recess 45 can be easily removed. Furthermore, when the circuit board 30 is separated into individual pieces as described later, breakage of the circuit board 30 can be prevented. Also, by placing the connecting portion 46 inside the circuit board 30 rather than the side surface 30e, the width of the circuit board 30 can be narrowed, and interference with other members can be prevented. Note that the shape of the recess 45 is not particularly limited, but from the viewpoint of efficiently separating the circuit board 30 into individual pieces, when viewed from the surface 30a side of the circuit board 30, it is preferable that the bottom is an arc. Also, the connecting portion 46 is formed by cutting a cutting line 49 (see FIG. 10) as described later. The shape of the connecting portion 46 reflects machining marks, machining accuracy, etc. of the machining tool that cuts the cutting line 49. For this reason, in FIGS. 7 and 8, the connecting portion 46 is parallel to the side surface 30e of the circuit board 30, but is not limited thereto and can have various shapes.

[0057] As shown in FIG. 9, the circuit board 30 has a front end portion 30b where the imaging element 29 is provided, a curved portion 30c, an inclined portion 30j, and a rear end portion 30k where connection pads 30d are provided in this order. The first bending axis Lb1 and the second bending axis Lb2 shown in FIGS. 7 and 8 are axes extending in the width direction Dw orthogonal to the extending direction Ds of the circuit board 30. For the circuit board 30 in the state shown in FIGS. 7 and 8, the portion ahead of the first bending axis Lb1 is raised so as to approach the surface 30a of the circuit board 30 to form the front end portion 30b and the curved portion 30c. Next, by lowering the portion behind the second bending axis Lb2 downward, the inclined portion 30j and the rear end portion 30k are formed. In this way, the front end portion 30b, the curved portion 30c, the inclined portion 30j, and the rear end portion 30k shown in FIG. 9 are formed.

[0058] An electronic component 31 for driving the imaging element 29 is provided on the surface 30a side of the circuit board 30 of the inclined portion 30j shown in FIG. 9. The inclined portion 30j is inclined but flat. By providing the electronic component 31 on the inclined portion 30j between the curved portion 30c and the rear end portion 30k instead of the rear end portion 30k, the space of the circuit board 30 can be effectively utilized, there is no need to prepare a space for mounting the electronic component 31, and the endoscope imaging apparatus 20 can be miniaturized. The inclined portion 30j can be formed, for example, by applying an adhesive and fixing it with a jig (not shown). As the above-mentioned adhesive, various known adhesives used in conventional endoscopes can be used. As the adhesive, for example, an epoxy-based adhesive, a silicone-based adhesive, or an acrylic-based adhesive can be used. Further, by providing a metal layer 30h and making the connecting portion 46 between the recesses 45 inside the circuit board 30 rather than on the side surface 30e, the inclined portion 30j can be formed. In the circuit board 30, since the portion with the metal layer 30h is difficult to bend, the inclined portion 30j (plane) is easily formed, and since the portion without the metal layer 30h is easy to bend, the curved portion 30c is easily formed. Therefore, by providing the metal layer 30h, the inclined portion 30j can be easily formed continuously with the curved portion 30c.

[0059] Here, FIG. 10 is a schematic plan view showing an example of a method for manufacturing a circuit board of an endoscope imaging apparatus according to an embodiment of the present invention. FIG. 10 shows a state in which one circuit board 30 is attached to a flexible board 47. Although not shown, a plurality of circuit boards 30 are surface-mounted on the flexible board 47. As shown in FIG. 10, cut lines 48 are provided around the circuit board 30. The cut lines 48 are, for example, those in which line portions penetrating the flexible board 47 are arranged with spaces therebetween. In addition, a runner portion 48a fitted in the recess 45 (see FIG. 7) is provided. Similar to the cut line 48, the runner portion 48a is, for example, formed by arranging line portions penetrating the flexible substrate 47 with a gap therebetween. By removing the runner portion 48a, the recess 45 (see FIG. 7) is formed.

[0060] On the flexible substrate 47, a cutting line 49 for separating the circuit board 30 from the flexible substrate 47 is provided in contact with the two runner portions 48a. The portion connected by the cutting line 49 becomes the connecting portion 46 of the above-mentioned circuit board 30. The cutting line 49 is provided parallel to the portion that becomes the side surface 30e of the circuit board 30 and inside the portion that becomes the side surface 30e (see FIG. 7) of the circuit board 30. The flexible substrate 47 is basically the same substrate as the circuit board 30 although the circuit pattern and the like are different. For example, it is composed of a flexible printed circuit board.

[0061] With the flexible substrate 47 attached, the imaging element 29 is electrically connected to the circuit board 30. After connecting the imaging element 29, the flexible substrate 47 is cut along the cutting line 49, and the flexible substrate 47 is removed with the cut line 48 and the runner portion 48a as boundaries, and the circuit board 30 is separated into individual pieces. When the circuit board 30 is small, it may be difficult to connect the imaging element 29 after separation. However, by connecting the imaging element 29 to the circuit board 30 before separating the circuit board 30, it is easy to connect the imaging element 29 even if the circuit board 30 is small. After separating the circuit board 30, the circuit board 30 is bent as described above at the first bending axis Lb1 and the second bending axis Lb2 shown in FIG. 7 to form the tip portion 30b, the curved portion 30c, the inclined portion 30j, and the rear end portion 30k.

[0062] In the endoscopic imaging apparatus 20, the observation image captured from the imaging lens 23 and taken into the imaging element 29 is formed on the light-receiving surface 29a of the imaging element 29 and converted into an electrical signal. This electrical signal is output to the processor device 16 (see FIG. 1) via the signal cable 32, converted into a video signal, and the observation image is displayed on a monitor connected to the processor device 16. In this case, in the endoscopic imaging apparatus 20, the optical image is accurately formed on the image-receiving surface of the imaging element, and a high-quality observation image can be obtained without image defects, defocus, etc.

[0063] In addition, in the holder 24 shown in FIG. 6, the arm portion 34b (see FIG. 4) is fixed to the outer outer surface 25c of the regulating member 25. For example, since the arm portion 34b is fixed using solder 37 (see FIGS. 2 and 5), it is preferable to perform a plating process on the region where the arm portion 34b is fixed, for example, the outer outer surface 25c of the regulating member 25, in order to facilitate the application of the solder 37. In the holder 24, for example, since the filter 26 is disposed on the surface 24c of the flange portion 24b, it is not desired to apply solder. Also, the holder 24 does not desire to apply solder to the joint surface with the lens barrel 22, that is, the inner surface of the through hole 24d. In the holder 24, it is preferable not to perform a plating process on the portion where it is not desired to apply solder. Also, in the holder 24, a portion without a plating portion serving as a solder barrier may be provided between the portion where it is not desired to apply solder and the portion where solder is to be applied. In the holder 24, the portion where it is not desired to apply solder is, for example, the attachment cylinder portion 24a and the front surface 24e on the attachment cylinder portion 24a side of the flange portion 24b.

[0064] Also, in the holder 24 shown in FIG. 4, it is preferable that the end portions 25a in the optical axis direction of the pair of regulating members 25 are located closer to the holder 24 side than the circuit board 30. Thereby, interference between the regulating member 25 and the circuit board 30 is suppressed when positioning the imaging element 29. Further, it is more preferable that the end portions 25a in the optical axis direction of the pair of regulating members 25 are located closer to the holder 24 side than the end portion on the signal cable 32 side of the imaging element 29. Thereby, after holding the imaging element 29, interference with the circuit board 30 can be further suppressed.

[0065] The imaging element 29 is preferably positioned using the flange portion 24b of the holder 24 shown in FIG. 6, at least one of the pair of regulating members 25, and the end surface 25b of the regulating member 25 in the vertical direction. That is, the imaging element 29 is positioned with respect to the optical axis C direction (X-axis direction) by abutting against the surface 24c of the flange portion 24b of the holder 24, and is positioned with respect to the width direction (Y direction) by abutting against the inner surface 25f (see FIGS. 4 and 6) of at least one of the pair of regulating members 25, and is positioned with respect to the vertical direction (Z direction) by abutting against a jig (not shown) in contact with the end surface 25b of the regulating member 25. Thereby, when positioning the imaging element 29, by using the end surface 25b of the regulating member 25, it becomes unnecessary to provide a positioning portion, and an increase in the size of the endoscope imaging apparatus 20 can be suppressed. Note that, for the above-described positioning between the imaging element 29 and the holder 24, the upper end surface in the vertical direction of the regulating member 25 may be used.

[0066] Here, the arm portion 34b is long, and a slight inclination results in a large deviation, and interference with other components occurs. On the other hand, providing a large number of positioning portions causes the endoscope imaging apparatus 20 to increase in size. Therefore, in the endoscope imaging apparatus 20, it is preferable that the holder 24 and the anchor 34 are positioned using the flange portion 24b of the holder 24, the pair of regulating members 25, and the end surface of the regulating member 25 in the vertical direction for the arm portion 34b of the anchor 34. Thereby, positioning between the arm portion 34b and the holder 24 becomes easy. In addition, since the lens barrel 22, the imaging element 29, and the anchor 34 can be positioned with respect to the 24 holders, positioning with less cumulative tolerance becomes possible. As a result, the number of positioning parts can be reduced, and an increase in the size of the endoscope imaging apparatus 20 can be suppressed. In addition, for the above-described positioning between the arm portion 34b and the holder 24, the upper end surface in the vertical direction of the regulating member 25 may be used, or the lower end surface 25b in the vertical direction may be used. When positioning is performed using the end surface 25b of the regulating member 25, for example, a jig (not shown) that contacts the end surface 25b of the regulating member 25 is used.

[0067] Note that, as shown in FIG. 4 described above, the optical axis C of the imaging lens 23 is not limited to the endoscope imaging apparatus 20 in which the optical axis C is perpendicular to the light receiving surface 29a of the imaging element 29. For example, the optical axis C of the imaging lens 23 may be parallel to the light receiving surface 29a of the imaging element 29. In this case, for example, a prism (not shown) is used to guide the light that has passed through the imaging lens 23 to the light receiving surface 29a of the imaging element 29. Note that, for example, a right-angle prism is used as the prism. By using a right-angle prism, the light that has passed through the imaging lens 23 is bent at a right angle.

[0068] FIG. 11 is a schematic side view showing an example of a connection form of a signal cable to a circuit board of the endoscope imaging apparatus according to an embodiment of the present invention, and FIG. 12 is a schematic plan view showing an example of a connection form of a signal cable to a circuit board of the endoscope imaging apparatus according to an embodiment of the present invention. In FIGS. 11 and 12, the same components as those of the endoscope imaging apparatus 20 shown in FIGS. 1 to 5 and the circuit board 30 shown in FIGS. 7 to 9 are denoted by the same reference numerals, and detailed description thereof is omitted. The endoscope imaging apparatus 20a shown in FIG. 11 is different from the endoscope imaging apparatus 20 shown in FIGS. 1 to 5 in that the anchor 34 (see FIG. 2) is not provided, the optical axis C of the imaging lens 23 is parallel to the light receiving surface 29a of the imaging element 29, the number of signal lines (not shown) of the signal cable 32 is 8, the prism 50 is provided, and the circuit board 52 is a straight board without a curved portion. Other configurations are the same as those of the endoscope imaging apparatus 20 shown in FIGS. 1 to 5 and the circuit board 30 shown in FIGS. 7 to 9. In FIGS. 11 and 12, the signal line 32a and the signal line 54 are emphasized, and the coating layer 32b is simplified. Also, the illustration of the imaging lens 23 is omitted.

[0069] In the endoscope imaging device 20a, a cover glass 28 is provided on the light receiving surface 29a of the imaging element 29. The prism 50 is, for example, a right-angled prism in which the incident surface 50a and the exit surface 50b are orthogonal. The prism 50 is disposed between the lens barrel 22 and the imaging element 29. The prism 50 is disposed with the incident surface 50a facing the surface on the proximal end side of the lens barrel 22. Also, the prism 50 is disposed with the exit surface 50b facing the light receiving surface 29a of the imaging element 29. Note that the prism 50 is an example of an optical member disposed between the lens barrel 22 and the imaging element 29. The optical member is not limited to the prism 50 as long as it can bend the optical axis C of the imaging lens 23 and guide the light that has passed through the imaging lens 23 to the light receiving surface 29a of the imaging element 29. Note that the prism 50 is not necessarily required depending on the arrangement position of the imaging element 29, and a configuration in which another optical member is disposed may be employed.

[0070] The circuit board 52 has basically the same configuration as the above-described circuit board 30 (see FIG. 2). The imaging element 29 is electrically connected to the surface 52a of the circuit board 52 from the distal end side. As shown in FIG. 12, a plurality of, for example, eight metal terminals 53 are provided on the rear end 52e side of the imaging element 29. The metal terminals 53 are arranged in two rows with four in each row. The metal terminal 53 is an end portion of a signal line (not shown) that is electrically connected to the imaging element 29. A connection pad 52c is provided on the rear end 52e side of the metal terminal 53. A metal layer 52d is provided on the back surface 52b of the circuit board 52 as shown in FIG. 11. The connection pads 52c shown in FIGS. 11 and 12 have the same configuration as the connection pads 30d (see FIG. 7) of the circuit board 30 described above. The metal layer 52d shown in FIG. 11 has the same configuration as the metal layer 30h (see FIG. 8) of the circuit board 30 described above. Both the connection pad 52c and the metal layer 52d are conductive films. The connection pad 52c is electrically connected to the metal layer 52d.

[0071] The metal terminal 53 shown in FIG. 12 is a terminal to which the signal lines 32a and 54 of the signal cable 32 are electrically connected, for example, by solder. The signal cable 32 has the same number of signal lines 32a, 54 as the metal terminal 53. The metal terminal 53 is such that when the signal lines 32a, 54 of the signal cable 32 are connected by solder or the like, the metal terminal 53 becomes a hardness change point.

[0072] In the circuit board 52, the connection pad 52c and the metal layer 52d are, similar to the connection pad 30d and the metal layer 30h of the circuit board 30 described above, when the circuit board 52 is viewed from the surface 52a side, the metal layer 52d overlaps the connection pad 52c and is provided in a wider range than the connection pad 52c. Thereby, similar to the endoscope imaging apparatus 20 described above, the metal layer 52d reinforces the circuit board 52, prevents local breakage at the hardness change point, and can prevent disconnection of wirings such as signal lines (not shown) of the circuit board 52. Note that even in a configuration where the circuit board 52 is a linear substrate without a curved portion, local breakage at the hardness change point can be prevented, and disconnection of signal lines (not shown) of the circuit board 52 can be prevented. Also, since the metal layer 52d also serves as a noise shield layer, high-frequency signals input to and output from the imaging element 29 or the electronic component 31 are less likely to be disturbed. Also, the connection pad 52c is also an electrical resistance change point. For example, noise is generated when the imaging element 29 is driven. Even when such noise is generated, the metal layer 52d can prevent leakage of noise generated from the imaging element 29 or the like, and can shield noise from the outside of the endoscope imaging apparatus 20.

[0073] Here, when the metal layer 52d overlaps with the connection pad 52c, it means that, similar to the metal layer 30h and the connection pad 30d, the entire connection pad 52c is within the metal layer 52d. Also, when the metal layer 52d is provided in a wider range than the connection pad 52c, it means that the area of the metal layer 52d is larger than the area of the connection pad 52c. Also in this case, similar to the above-described metal layer 30h, it is preferable that the metal layer 52d is about three times as large as the connection pad 52c in terms of the thickness of the circuit board 52. The connection pad 52c, the metal layer 52d, the metal terminal 53, and the signal line (not shown) of the circuit board 52 are made of copper, for example, in the same way as the wiring layer of a flexible printed circuit board.

[0074] In the endoscopic imaging device 20a, the signal line 32a of the signal cable 32 is electrically connected to the metal terminal 53. For example, when the signal cable 32 is pulled due to the bending operation of the endoscope, among the plurality of signal lines 32a, the signal line 32a with the shortest slack length and the largest tension applied first is likely to be disconnected. When the signal line 32a with the shortest slack length is thinner than the other lines, it is more likely to be disconnected. Therefore, as shown in FIG. 12, among the plurality of signal lines 32a, the slack length of the thickest and strongest signal line 54 is made the shortest. As a result, the tension is first applied to the signal line 54 with the shortest slack length, but since the signal line 54 has high strength, it is not likely to be disconnected even when tension is applied. In this way, the occurrence of disconnection of the signal lines of the signal cable 32 can be suppressed. When manufacturing the signal cable 32, among the plurality of signal lines, one signal line is made thicker than the other signal lines. The slack length of the thick signal line is made the shortest among the plurality of signal lines and is connected to the metal terminal 53 using, for example, solder. Note that the configuration is not limited to making one signal line of the signal cable 32 thick, and a plurality of signal lines with different thicknesses may be prepared, and the slack length of the thickest signal line may be made the shortest among the plurality of signal lines. Note that, also in the circuit board 52, when the circuit board 52 has a multilayer wiring structure as in the above-described circuit board 30, the metal layer 52d may be provided on the surface of another layer in which the connection pad 52c is not provided among the multilayer wiring layers of the circuit board having the multilayer wiring structure, or on the surface of a plurality of layers including another layer.

[0075] The present invention is basically configured as described above. As described in detail above, the endoscopic imaging apparatus and the endoscope of the present invention are not limited to the above-described embodiments, and various improvements or modifications may of course be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0076] 10 Endoscope system 12 Endoscope 14 Light source device 16 Processor device 20, 20a Endoscopic imaging device 22 Lens barrel 22a Inside 23 Imaging lens 24 Holder 24a Mounting cylinder portion 24b Flange portion 24c Surface 24d Through hole 24e Front surface 25 Regulation member 25a End portion 25b End face 25c Outer surface 25d Recess 25f Inner surface 26 Filter 27 Mask 27a Hole 28 Cover glass 29 Image sensor 29a Light receiving surface 30, 52 Circuit board 30a, 52a Surface 30b Tip portion 30c Curved portion 30d, 52c Connection pad 30e Side surface Inner surfaces of 30g and 52b Metal layers of 30h and 52d Inclined portion of 30j Rear end portion of 30k Rear end of 30p Electronic component 31 Signal cable 32 Signal lines 32a and 54 Coating layer of 32b Shield conductor of 32c Outer sheath of 32d Bump 33 Anchor 34 Bottom portion of 34a Arm portion of 34b Base material portion of 34c Retention portion of 34d Gap of 34e Groove of 34f End face of 34g Base end of 35a Tip end of 35b Solder 37 Connection terminal 40 Signal line 41 Connection portion 42 Region 43 Connection member 44 Recessed portion 45 Connection portion 46 Flexible substrate 47 Score line 48 Runner portion of 48a Cutting line 49 Prism 50 Incident surface of 50a Exit surface of 50b Metal terminal 53 Optical axis C Extension direction Ds Width direction Dw First bending axis Lb1 Second bending axis Lb2

Claims

1. An endoscope imaging device for acquiring an image of an object to be observed, comprising: a lens barrel having an imaging lens provided therein; an imaging element that receives light that has passed through the imaging lens and performs photoelectric conversion; a circuit board to which the imaging element is electrically connected; a signal cable electrically connected to the circuit board, wherein a connection pad to which the signal cable is electrically connected is provided on one surface of the circuit board, and a metal layer is provided on the other surface opposite to the one surface of the circuit board, and when the circuit board is viewed from the one surface side or the other surface side, the metal layer overlaps the connection pad and is provided in a range wider than the connection pad. The endoscope imaging device.

2. A signal line is provided on the one surface of the circuit board, and a connection member is provided on the other surface of the circuit board. The imaging element is electrically connected to the connection member and is provided on the other surface. The endoscope imaging device according to claim 1, wherein the connection member is electrically connected to the signal line in a region of the one surface on the opposite side of the surface where the imaging element is provided.

3. The circuit board is provided with a recess connected by a connecting portion on a side surface in a width direction orthogonal to an extending direction of the circuit board. The endoscope imaging device according to claim 1 or 2, wherein the connecting portion is inside the circuit board with respect to the side surface.

4. The circuit board has, in this order, a tip portion where the imaging element is provided, a curved portion, an inclined portion, and a rear end portion where the connection pad is provided. The endoscope imaging device according to any one of claims 1 to 3, wherein an electronic component for driving the imaging element is provided on the one surface of the circuit board at the inclined portion.

5. The endoscope imaging device according to any one of claims 1 to 4, wherein an optical axis of the imaging lens is perpendicular to a light receiving surface of the imaging element.

6. The endoscope imaging device according to any one of claims 1 to 4, wherein an optical axis of the imaging lens is parallel to a light receiving surface of the imaging element.

7. The endoscope imaging device according to any one of claims 1 to 6, wherein the metal layer is electrically connected to a ground.

8. An endoscope having the endoscope imaging device according to any one of claims 1 to 7.

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