JP2000299806A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device where even thin cover glass has a similar effect to that of thick cover glass and an unnecessary surrounding light does not enter an output picture area even without the need for a light shield mask and for an increased outer diameter. SOLUTION: This image pickup device comprises an image pickup optical system and an image pickup element, and an optical member 19 whose outer size is larger than a cover glass 11 in at least one diagonal direction of an output picture area of a light receiving face is placed adjacently to an object side of the cover glass 11 of the image pickup element. A thickness TA of the optical member 19 is selected equal to or less than a thickness TB of the cover glass 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus having an image pickup optical system and an image pickup device, and more particularly to a very small image pickup apparatus such as an electronic endoscope.

[0002]

2. Description of the Related Art Generally, in an image pickup apparatus, as a light shielding means for shielding unnecessary peripheral light incident from outside the visual field range,
It is known to arrange a light-shielding mask near an image sensor. FIG. 8 shows a general configuration of an imaging device. Fig. 8 (a)
As shown in FIG. 1, an imaging device 1 includes an imaging optical system 2 and an imaging device 3.
And the imaging optical system 2 is in a frame 4 and the imaging device 3 is in a frame 5
Each is stored in. In FIG. 8A, light 6 from an object is imaged on the image output area 8 of the light receiving surface 7 of the image sensor 3 via the image pickup optical system 2. The image output area 8 is a range on the light receiving surface 7 that is actually output as an image on the monitor, and becomes the maximum when the same as the maximum range (effective imaging area) of the light receiving surface 7. Further, the range of the image output area 8 is electrically adjusted by signal processing of the image sensor 3 and thereafter by a control unit (not shown). The image output area 8 of the image sensor 3 is generally rectangular as shown in FIG. 8B, and the image pickup optical system 2 has a circular image forming area whose diameter is larger than the diagonal line of the image output area 8. 9 is configured to image light. In the case of such an optical configuration, the unnecessary peripheral light 16 becomes the largest in the range 10 particularly in the opposite side direction (up, down, left and right directions) of the image output area 8, and the unnecessary peripheral light 1 is increased.
The light 6 is reflected on the side surface 12 of the cover glass 11 having a rectangular shape disposed in front of the light receiving surface 7, and adversely affects the image as a flare. Therefore, unnecessary ambient light 1
Normally, a light-shielding mask 13 whose hole shape matches the shape of the image output area 8 is arranged near the cover glass 11 in order to shield the light 6 from light.

On the other hand, in the case of a very small image pickup device, for example, the inner diameter of a frame is about 2 mm or 1.5 mm or less,
If a light-shielding mask is provided to shield unnecessary peripheral light, high precision is required for position adjustment between the light-shielding mask and the imaging area, and it takes time and effort to assemble. Therefore, recently, without arranging a special light shielding mask near the image sensor,
Light shielding means for shielding unnecessary ambient light has been proposed. For example, the image pickup apparatus described in Japanese Patent Application Laid-Open No. 8-160339 discloses a method of increasing the area of the entrance surface of the cover glass or preventing the unnecessary peripheral light reflected on the side surface of the cover glass from entering the image output area. And the thickness is reduced.

[0004]

However, if there is dust or a flaw on the surface through which light passes, it is undesirably projected on the light receiving surface. The projected dust and flaws near the light receiving surface become denser and have a clearer contour, and become an annoying presence in the observed image. This is related to the beam diameter,
The smaller the beam diameter, the more conspicuous dust and scratches become. As shown in FIG. 9, in particular, the object-side surface 14 of the cover glass 11 is close to the light receiving surface 7 and has a small luminous flux diameter φ. In addition, dust remaining in the frame easily adheres. Therefore, it is necessary to increase the thickness t of the cover glass 11 to t ′, to separate the position of the object-side surface 14 of the cover glass 11 from the light receiving surface to some extent, and to increase the luminous flux diameter φ to φ ′. is there. In recent years, in order to improve the image quality of an imaging device, the number of pixels of the imaging device has been increased, while the pixel pitch has been reduced in order to keep the size of the outer shape of the imaging device unchanged. Since the depth of field becomes shallower as the pixel pitch becomes smaller, it is necessary to further increase the F-number of the imaging optical system, that is, to stop down the diaphragm 15 in order to maintain the same depth of field. Then, the luminous flux diameter becomes smaller, so the cover glass 1
1 needs to be made even thicker. However, the ordinary image sensor, its light receiving surface and the image output area have a rectangular shape, and the cover glass generally has a rectangular shape. At this time, if the cover glass 11 is made thicker as t 'in order to prevent the above dust and scratches, unnecessary peripheral light reflected on the side surface 12 of the cover glass 11 which is not a problem when the thickness is t, especially unnecessary in the opposite side direction. It is not preferable because the ambient light 16 'enters the image output area 8.

Therefore, the present invention has the same effect as increasing the thickness of the cover glass without increasing the thickness of the cover glass. Unnecessary peripheral light can be output without increasing the outer diameter and without using a light-shielding mask. It is an object of the present invention to provide an imaging device capable of preventing the imaging device from entering.

[0006]

In order to achieve the above object, an image pickup apparatus according to the present invention comprises: an image pickup apparatus having an image pickup optical system and an image pickup element; An optical member having an outer dimension larger than that of the cover glass is disposed adjacent to at least one opposite side of the image output area of the light receiving surface of the element.

[0007] Further, the imaging apparatus of the present invention preferably comprises:
The thickness of the optical member is equal to or less than the thickness of the cover glass.

[0008] Further, the imaging apparatus of the present invention preferably comprises:
The outer diameter of the optical member is equal to or less than the outer diameter of a circumscribed circle of the cover glass or the outer diameter of the circumscribed circle of the imaging element.

[0009] The imaging apparatus of the present invention preferably comprises:
It is characterized by satisfying the following expression (3) or expression (4). T ≧ 0.0002 · n / (2 · P · tan (1 / 2Fno)) (3) T ≧ 0.001 / P (4) where T is the above optical member and the above The total thickness of the cover glass, n is the refractive index of the optical member, Fno is the F number of the imaging optical system, and P is the pixel pitch of the imaging device.

[0010] Further, the imaging apparatus of the present invention preferably comprises:
It is characterized by satisfying the following expression (6) in a direction in which the numerical value obtained by the following expression (5) is minimum. LAS-IH (5) sin θ ≦ n (LAS-IH) / √ (T ² + (LAS-IH) ² ) (6) where LAS is measured from the optical axis of the imaging optical system. The distance to the side surface of the optical member, IH is the distance from the optical axis of the imaging optical system to the corner of the image output area, and θ is the distance between the principal axis traveling toward the corner of the image output area and the optical axis incident on the optical member. The angle, n indicates the refractive index of the optical member, and T indicates the total length of the optical member and the cover glass.

[0011] The imaging apparatus of the present invention preferably comprises:
The optical member and the cover glass are adhered,
The center of the optical member substantially coincides with the center of the image output area of the imaging device, and the adhesive is an ultraviolet curing type or a combination type of ultraviolet curing and heat curing, and the following formula (7), ( 8)
Is satisfied. Ng <1.6 ... (7) | Ng-Nc | <0.1 ... (8) where Ng is the refractive index of the optical member or the cover glass, and Nc is the adhesive. Indicates the refractive index.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the operation of the imaging apparatus according to the present invention will be described with reference to FIG. FIGS. 1A and 1B are explanatory views of a main part of an imaging apparatus according to the present invention. FIG. 1A is a side view, and FIG. In FIG. 1A, unnecessary ambient light 1
6 is reflected by the side surface 12 of the cover glass 11 and then goes to the light receiving surface 7 side. Here, if the thickness of the cover glass 11 is increased in order to prevent dust from being seen, the unnecessary ambient light 16 is placed on the side surface 12 of the cover glass 11 at a position further away from the light receiving surface 7.
And it easily enters the image output area 8.
The image pickup apparatus of the present embodiment does not increase the thickness of the cover glass 11 but has a larger outer dimension than the cover glass 11 in the opposite side direction (up, down, left and right directions) of the cover glass 11, for example, as shown in FIG. Such a circular optical member 17 is arranged adjacent to or bonded to the object side of the cover glass 11. For this reason, the unnecessary ambient light 16 ′ is further separated from the optical axis 18 of the imaging optical system, is reflected on the side surface 19 of the optical member 17, and then is blocked by the surface portion 22 not in contact with the cover glass 11. Therefore, according to the imaging apparatus of the present invention, the image output area 8 is smaller than when the cover glass is simply thickened.
Unnecessary ambient light can be prevented from entering. In addition, since the outer diameter of the imaging device cannot be originally made smaller than the outer diameter of the circumcircle 20 of the imaging device,
It is preferable that the outer diameter of the image pickup device be equal to or smaller than the outer diameter of the circumcircle of the cover glass 11 or equal to or smaller than the outer diameter of the circumscribed circle 20 of the image sensor because the outer diameter of the image pickup apparatus does not increase.

Further, the optical member 17 and the cover glass 11
When bonding is performed, dust and scratches are not formed on the bonding surface 21 after bonding, but may be slightly scratched before bonding. It is good if the scratch is filled with the adhesive, but if the bubble is slightly filled and not filled, the bubble is undesirably formed as a shadow on the image. In the imaging device of the present invention, the influence of the flaw of the bonding surface 21 is reduced by making the bonding surface 21 as far as possible from the light receiving surface 7 of the image sensor. In order to make the joining surface 21 as far as possible from the light receiving surface 7 of the image sensor, the thickness TA of the optical member 17 is set to be equal to or less than the thickness TB of the cover glass 11, and the position of the joining surface 21 This is preferable because the light flux at the lens becomes large, and as a result, the shadow due to the scratch can be reduced.

Here, the dimensional relationship between the optical member 17 of the present invention and the cover glass 11 can be expressed as follows. In at least one opposite side direction of the image display area, LA> LB ... (1) where LA is the distance from the optical axis of the imaging optical system to one side surface of the optical member 17, and LB is the light of the imaging optical system. The distance from the axis to one side surface of the cover glass 11 is shown. TA ≦ TB (2) where TA indicates the thickness of the optical member 17 and TB indicates the thickness of the cover glass 11.

Here, the thickness TB of the cover glass 11 preferably satisfies the following conditions. The light beam diameter Φ _B (mm) on the object-side surface of the cover glass 11 preferably satisfies Φ _B ≧ 0.00008 / P. Here, P indicates the pixel pitch (mm) of the image sensor. Therefore, TB ≧ 0.00008 · n _B / (2 · P · tan
(1 / 2Fno)) is preferably satisfied. However, n _B is the refractive index of the cover glass 11, Fno denotes the F-number of the imaging optical system. In the case of an endoscope imaging apparatus, it is preferable that TB ≧ 0.0004 / P is satisfied in consideration of n _B and Fno. If this is not satisfied, for example, if there is a flaw in the joint surface, the shadow of the flaw will be reflected in the image, especially in an endoscope, since the diagnosis is performed from the image, such a shadow becomes very obstructive, This will hinder accurate diagnosis. More preferably, TB ≧ 0.00016 · n _B / (2 · P · tan
(1 / 2Fno)) It is preferable that TB ≧ 0.0008 / P is satisfied.

The luminous flux diameter Φ (mm) on the object-side surface of the optical member 17 can be expressed as follows: Φ = 2 · (T / n) · tan (1 / 2Fno) Here, T indicates the total thickness of the optical member 17 and the cover glass 11, and n indicates the refractive index of the optical member 17. When the pixel pitch is reduced, the shadow becomes more conspicuous even if the diameter of the light beam and the size of the dust are the same as when the pixel pitch is not reduced. Therefore, assuming that the pixel pitch of the image sensor is P (mm), it is preferable that the following expression be satisfied in practical use. Φ ≧ 0.0002 / P Therefore, it is preferable to satisfy the following conditional expression (3). T ≧ 0.0002 · n / (2 · P · tan (1 / 2Fno)) (3) In the case of an imaging device for an endoscope, the following conditional expression is used in consideration of n and Fno. It is preferable to satisfy (4). T ≧ 0.001 / P (4) If this is not satisfied, the shadow of dust is reflected on the image, and it is difficult to perform an accurate diagnosis with an endoscope. More preferably, it is preferable to satisfy the following conditional expressions (3 ′) and (4 ′). T ≧ 0.0004 · n / (2 · P · tan (１ ／ Fno)) (3 ′) T ≧ 0.002 / P (4 ′)

Furthermore, it is preferable that the imaging apparatus of the present invention satisfies the expression (6) in the direction S where the numerical value obtained by the following expression (5) is minimum. LAS-IH (5) where LAS is the distance from the optical axis of the imaging optical system to the side surface of the optical member 17, and IH is the distance from the optical axis of the imaging optical system to the corner of the image output area 8. Show. sin θ ≦ n (LAS-IH) / √ (T ² + (LAS-IH) ² ) (6) where θ is the optical axis of the principal ray incident on the optical member 17 toward the corner of the image output area 8. And the angle between them. Expression (6) is a conditional expression for preventing unnecessary ambient light from the imaging optical system from entering the image output area 8 after being reflected by the side surface of the optical member 17.

FIG. 2 is a partial sectional view taken in the direction S in FIG.
Shown in The S direction is a direction in which the numerical value obtained by the equation (5) becomes the minimum, and
Therefore, unnecessary peripheral light reflected on the side surface of the optical member 17 is most likely to enter the image output area 8 in the S direction. Consider a principal ray emitted from the exit pupil 23 of the imaging optical system. The light ray 16 is unnecessary ambient light, is reflected at a position closest to the object on the side surface 19 of the optical member 17, and reaches the corner 25 of the image output area 8. 2 is a state just before the unnecessary peripheral light 16 does not enter the image output area 8, and if the incident angle of the unnecessary peripheral light 16 to the optical member 17 is equal to or smaller than θ, the unnecessary ambient light 16 reaches the image output area 8. Not preferred. For that purpose, it is essential that at least the incident angle of the most peripheral chief ray 24 in the visual field be equal to or smaller than θ.

According to Snell's law, sinθ = n · sinθ ′, while (LAS-IH) / √ (T ² + (LAS-IH) ² ) =
sin θ ′. From the above, it is essential to satisfy the following conditional expression (6). sin θ ≦ n (LAS-IH) / √ (T ² + (LAS-IH) ² ) (6)

Next, an imaging optical system satisfying conditional expression (6) will be described. From the object side, as shown in FIG.
Aperture stop, in the positive imaging optical system composed of the group after the angle theta "is, theta" positive rear group of the exit light ^{= θ'-tan -1 (h /} f p) = tan -1 ( h / l) -tan can be expressed as ^-1 (h / f _p). Here, h is the ray height of the most peripheral chief ray, l is the distance from the aperture stop to the rear group positive lens, f _P
Indicates the focal length of the rear group. Therefore, from θ ″ = θ, sin (tan ⁻¹ (h / l) −tan ⁻¹ (h / f _P )) ≦ the right side of the conditional expression (6)... (A) What is necessary is just to put a lens in a rear group.

When the lens immediately before the image pickup device in the rear group is a plano-convex lens convex on the image side as shown in FIG. 3B, sin θ ₁ = n _L sin θ ₁ 'θ ₁ ' = sin ^-1 (Sin θ ₁ / n _L ) θ ₂ = β−θ ₁ ′ = β−sin ⁻¹ (sin θ ₁ / n _L ) β = sin ⁻¹ (h ₂ / R) Where θ ₁ is the angle of incidence on the plano-convex lens, θ ₁ ′ is the refraction angle, n _L is the refractive index of the plano-convex lens, and R
The radius of curvature of the plano-convex lens, h ₂ is the height of light rays emitted from the plano-convex lens, theta ₂ is the incident angle of the second surface, theta ₂ 'represents an exit angle from the second surface. Also, n _L sin θ ₂ = sin
From (β−θ ₂ ′), θ ₂ ′ = β−sin ⁻¹ (n _L sin θ ₂ ). Thus, from θ ₂ ′ = θ, β−sin ⁻¹ (n _L sin θ ₂ ) ≦ conditional expression (6) (B) n _L and R may be determined so as to satisfy this.

When the lens immediately before the image pickup device in the rear group is a convex-convex lens having a convex surface on the object side as shown in FIG. 3C, n _L sin θ ₂ = sin θ ₂ 'θ ₂ = θ ₁ ' −β θ ₂ ′ = sin ⁻¹ (n _L sin (θ ₁ ′ −β)). Where sin (θ ₁ + β) =
From n _L sin θ ₁ ′, θ ₁ ′ = sin ⁻¹ (sin (θ ₁ + β) / n _L ) β = sin ⁻¹ (h ₁ / R) Further, θ ₁ is an incident angle to the convex-planar lens, θ ₁ 'is the angle of refraction,
n _L is the refractive index of the convex / planar lens, R is the radius of curvature of the convex / planar lens, h ₁ is the height of incident light on the convex / planar lens, θ ₂ is the angle of incidence on the second surface, and θ ₂ ′ is the angle from the second surface. Indicates the exit angle. Therefore, from θ ₂ ′ = θ, sin ⁻¹ (n _L sin (θ ₁ ′ −β)) ≦ the right side of the conditional expression (6)... (C) n _L and R are set so as to satisfy this. You just have to decide.

Hereinafter, the present invention will be described with reference to examples. Embodiment 1 FIG. 4 shows a first embodiment of the present invention, in which (a) is a sectional view and (b)
FIG. 3A is a diagram of a main part of FIG. The imaging device 1 is an imaging device for an endoscope, and includes an imaging optical system 2 and a CCD 44 as shown in FIG. The imaging optical system 2 includes a first lens 3 arranged on a lens frame 38 in order from the object side.
1. Laser cut interference filter 32, second lens 3
3, optical components such as a color correction absorption filter 34 and a third lens 35, a spacing ring 41, and flare stops 40 and 43 and a brightness stop 42 of a phosphor bronze plate, respectively. On the object side of the cover glass 37 of the CCD 44, a circular optical member 36 is joined in a state where the center thereof is aligned with the center of the image output area 8 as shown in FIG. After being joined to the optical member 36, the CCD 44 is combined with the CCD frame 39 as shown in FIG. That is, the optical member 36 having an adhesive on the side surface is inserted into the CCD frame 39 from the right side of the figure, and
The image-side surface 45 of the frame 39 is fixed so as to abut against the object-side surfaces 46 at the four corners of the cover glass 37, and further contains, for example, carbon from the side surface of the cover glass 37 to the image-side surface 45 of the CCD frame 39. A black adhesive 47 is provided. In addition, if there is a chip 48 on the ridgeline portion on the object side of the cover glass 37, it causes flare. Therefore, the chip 47 is filled with the adhesive 47. In this case, the cover glass 37
When the difference between the refractive index of the adhesive and the adhesive is 0.1 or less, it is preferable because the reflection at the boundary between the cover glass 37 and the adhesive can be suppressed. Note that, as described above, any black adhesive mixed with carbon (soot) or the like is preferable because it can absorb flare. On the other hand, if the chip is too large, air bubbles may enter the pad when the pad is filled with the adhesive, and the chip may not be filled properly. Therefore, it is preferable that the size of the cover glass 37 is 100 μm or less, and preferably 50 μm or less, even if a chip is generated.

In the image pickup apparatus of this embodiment, the image pickup optical system and the optical members are as follows: LA = 0.65, LB = 0.6, TA = 0.4, TB =
0.4, IH = 0.5, LAS = 0.65, P = 0.0
04. The lens data is shown below. Object distance = 20, Fno = 3.6 r ₁ = ∞ d ₁ = 0.2000 n ₁ = 1.88300 ν ₁ = 40.76 r ₂ = 0.4910 d ₂ = 0.2160 r ₃ = ∞ d ₃ = 0.4000 n ₃ = 1.52287 v ₃ = 59.89 r ₄ = ∞d ₄ = 0.1000 r ₅ = 2.4060 d ₅ = 0.8000 n ₅ = 1.90135 v ₅ = 31.55 r ₆ = −1.0090 d ₆ = 0.0200 r ₇ = ∞ (brightness stop) d ₇ = 0.0300 r ₈ = ∞ d ₈ = 0.4000 n ₈ = 1.51400 ν ₈ = 75.00 _{r 9 = ∞ d 9 = 0.0300} r 10 = ∞ d 10 = 0.8800 n 10 = 1.88300 ν 10 = 40.76 r 11 = -2.4610 d 11 = 0.3000 r 12 = ∞ d _{12 = 0.4000 n 12 = 1.51633 ν} 12 = 64.15 r 13 = ∞ d 13 _{0.0100 n 13 = 1.54500 ν 13 =} 63.00 r 14 = ∞ d 14 = 0.4000 n 14 = 1.50600 ν 14 = 63.00 r 15 = ∞ d 15 = 0.0100 n 15 = 1.54500 ν ₁₅ = 63.00 r ₁₆ = ∞ where r ₁ , r ₂ , _... Are the radii of curvature of the respective surfaces of the lens,
.., d ₁ , d ₂ , _...
n ₁ , n ₂ , _... are the refractive indexes of the respective lenses, ν ₁ , ν ₂ ,
_... is the number of Abpe of each lens. Also, the radius of curvature,
Wall thickness, air gap, LA, LB, TA, TB, IH, LA
The unit of S, P, and the object distance is mm.

Embodiment 2 FIGS. 5A and 5B show a second embodiment of the present invention, wherein FIG.
FIG. 3A is a diagram of a main part of FIG. In this embodiment, the optical member 51 is formed by joining the optical members 49 and 50 having the same shape to each other, and is joined to the cover glass 37. The optical members 49 and 50 are both infrared absorbing glasses, but have different materials and spectral characteristics. In the image pickup apparatus according to the present embodiment, the image pickup element and the optical member have LA = 1.5, LB = 1, TA = 1.6, and TB = 0.
4, IH = 1.2, LAS = 1.2, P = 0,002. The lens data is as follows. Object distance = 15, Fno = 5.76 r ₁ = ∞ d ₁ = 0.51 n ₁ = 1.51633 ν ₁ = 64.1 r ₂ = 1.014 d ₂ = 0.19 r ₃ = -3. _{072 d 3 = 1.14 n 3 =} 1.69680 ν 3 = 55.5 r 4 = -0.900 d 4 = 0.05 r 5 = 3.440 d 5 = 0.71 n 5 = 1.69680 ν ₅ = 55.5 r ₆ = -1.654 d ₆ = 0.30 n ₆ = 1.92286 ν ₆ = 21.3 r ₇ = -11.860 d ₇ = 0.39 r ₈ = ∞ d _{8 = 1.00 n 8 = 1.52400 ν 8} = 65.6 r 9 = ∞ d 9 = 0.60 n 9 = 1.53000 ν 9 = 60.0 r 10 = ∞ d 10 = 0.40 n 10 = 1.54000 ν ₁₀ = 40.0 r ₁₁ = ∞ where r ₁ , r ₂ , _... Are the radii of curvature of the respective surfaces of the lens,
.., d ₁ , d ₂ , _...
n ₁ , n ₂ , _... are the refractive indexes of the respective lenses, ν ₁ , ν ₂ ,
_... is the number of Abpe of each lens. Also, the radius of curvature,
Wall thickness, air gap, LA, LB, TA, TB, IH, LA
The unit of S, P, and the object distance is mm.

Embodiment 3 FIG. 6 is a sectional view showing a third embodiment of the present invention. In the present embodiment, the optical member 49 is not bonded to the cover glass 37, and the gap 52 is open. The periphery of the gap 52 is sealed with an adhesive 53 so that dust does not enter later. The optical member 49 is an infrared absorbing glass, and an interference film for cutting laser light for endoscopic treatment is deposited on both surfaces thereof. In addition, even if the gap is vacuum, air,
It may be filled with an adhesive or a transparent gel material.

In addition, in the image pickup apparatus of the present invention, as shown in FIG. 7 (a), the optical member 36 may have a curvature on the object side surface. As shown in b4), the outer shape of the optical member 36 may be a polygon. Here, the outer diameter of the optical member 36 in FIG. 7 (b1) is an octagon, and the outer diameter of the optical member 36 in FIGS. 7 (b2) to 7 (b4) is a shape obtained by cutting a part of a circle. . FIG. 7 (b2) is a view cut along one side of the cover glass, FIG. 7 (b3) is a view cut along two opposite sides of the cover glass,
FIG. 7 (b4) shows the cover glass cut along each side. Further, the optical member and the cover glass may be made of the same glass, or may be made of different glasses having different refractive indexes. However, the smaller the refractive index is, the larger the air-equivalent length can be made with the same thickness, which is effective in reducing the size of the imaging device. For example, the expression
It is preferable to satisfy (7). Ng <1.6 (7) where Ng indicates the refractive index of the optical member or the cover glass. Further, the refractive index of the adhesive for joining the optical member and the cover glass is preferably about the same as those of the members, and for example, preferably satisfies the following expression (8). | Ng−Nc | <0.1 (8) where Nc indicates the refractive index of the adhesive. As the adhesive used for bonding, it is preferable from the viewpoint of resistance to use a type that is cured by ultraviolet rays or a type that uses both curing by ultraviolet rays and curing by heat. According to these types of adhesives, when the center of the optical member is aligned with the center of the image output area, the position of the optical member can be quickly cured with ultraviolet light after adjusting the bonding position, and the position can be fixed. This is convenient in that no problem occurs.

As described above, in addition to the features described in the claims, the imaging device according to the present invention has the following (1)
It also has features as shown in (11).

(1) An image pickup optical system and an image pickup element are provided, and there is no light-blocking mask having a rectangular hole near the image pickup element. At least one of the image output areas of the light receiving surface is provided on the object side of the cover glass of the image pickup element. An imaging device, wherein an optical member having an outer dimension larger than a cover glass is arranged adjacent to two opposite sides.

(2) An image pickup optical system and an image pickup element are provided, and an optical member is disposed adjacent to the object side of the cover glass of the image pickup element.
An imaging device that satisfies (1). LA> LB (1) where LA is the distance from the optical axis of the imaging optical system to the side surface of the optical member, and LB is the distance from the optical axis of the imaging optical system to the side surface of the cover glass.

(3) The imaging device according to (1) or (2), wherein the optical member and a cover glass are joined.

(4) The imaging device according to any one of the above (1) to (3), wherein the following expression (2) is satisfied. TA ≦ TB (2) where TA is the thickness of the optical member and TB is the thickness of the cover glass.

(5) The optical member according to any one of (1) to (4), wherein the outer diameter of the optical member is equal to or less than the outer diameter of the circumcircle of the cover glass or equal to or less than the outer diameter of the circumcircle of the imaging element. An imaging device according to claim 1.

(6) The imaging device according to any one of the above (1) to (4), wherein the following expression (3) or (4) is satisfied. T ≧ 0.0002 · n / (2 · P · tan (1 / 2Fno)) (3) T ≧ 0.001 / P (4) where T is an optical member and a cover glass. Total thickness,
n is the refractive index of the optical member, Fno is the F number of the imaging optical system, and P is the pixel pitch of the imaging device.

(7) The imaging apparatus according to any one of the above (1) to (4), wherein the following expression (3 ′) or expression (4 ′) is satisfied. T ≧ 0.0004 · n / (2 · P · tan (1 / 2Fno)) (3 ′) T ≧ 0.002 / P (4 ′) where T is an optical member. The total thickness of the cover glass,
n is the refractive index of the optical member, Fno is the F number of the imaging optical system, and P is the pixel pitch of the imaging device.

(8) The imaging apparatus according to the above (6) or (7), wherein the following expression (6) is satisfied in the direction in which the numerical value obtained by the following expression (5) is minimum. LAS-IH (5) sinθ ≦ n (LAS-IH) / √ (T ² + (LAS-IH) ² ) (6) where LAS is optical from the optical axis of the imaging optical system. The distance to the side surface of the member, IH is the distance from the optical axis of the imaging optical system to the corner of the image output area, θ is the angle of the principal ray going to the corner of the image output area with the optical axis incident on the optical member, and n is The refractive index of the optical member,
T indicates the total length of the optical member and the cover glass.

(9) The imaging apparatus according to any one of the above (1) to (4), wherein the following conditional expressions (7) and (8) are satisfied. Ng <1.6 · · · · (7) | Ng-Nc | <0.1 · · · (8) where Ng is the refractive index of the optical member or the cover glass, and N
c indicates the refractive index of the adhesive.

(10) The center of the optical member substantially coincides with the center of the image display area, and an ultraviolet-curing adhesive or a combination of ultraviolet-curing and heat-curing adhesive is used for bonding the optical member to the cover glass. The imaging device according to the above (9), which is used in combination.

(11) The size of the chip of the cover glass is 100
(9) The imaging device according to the above (9), which is not more than 50 μm.

[0040]

As described above, according to the present invention,
Even if the thickness of the cover glass is increased, it is possible to provide an imaging device in which unnecessary ambient light does not enter the image output area without increasing the outer diameter.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory views of a main part for explaining an operation of an imaging apparatus according to the present invention, wherein FIG. 1A is a side view and FIG.

FIG. 2 is a partial cross-sectional view as seen in the direction of arrow S in FIG. 1 (b).

FIG. 3 is a diagram for explaining conditions in the imaging optical system of the present invention; FIG. 3A is a diagram for explaining conditions for satisfying the imaging optical system of the present invention in a general imaging optical system; (b) is a diagram for explaining conditions for satisfying the imaging optical system of the present invention in a case where the lens immediately before the imaging element in the rear group is a plano-convex lens, and (c) is a diagram illustrating the lens immediately before the imaging element in the rear group. FIG. 3 is a diagram for explaining conditions for satisfying the imaging optical system of the present invention when the lens is a convex flat lens.

FIG. 4 shows a first embodiment of the present invention, in which (a) is a sectional view,
(b) is a diagram of the main part of (a) viewed from the object side.

FIG. 5 shows a second embodiment of the present invention, wherein (a) is a sectional view,
(b) is a diagram of the main part of (a) viewed from the object side.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

FIG. 7A is a sectional view of a main part showing a fourth embodiment of the present invention;
(b1) is a diagram showing the shape of the optical member when the fifth embodiment of the present invention is viewed from the object side, and (b2) to (b4) are diagrams showing other shapes of the optical member.

8A and 8B show a conventional imaging device, wherein FIG. 8A is a cross-sectional view, and FIG.
FIG. 3A is a diagram of a main part viewed from the object side.

FIG. 9 is a cross-sectional view illustrating a conventional imaging device.

[Explanation of symbols]

REFERENCE SIGNS LIST 11 cover glass 12 side surface of cover glass 13 light-shielding mask 14 surface of cover glass on object side 15 aperture 16 unnecessary ambient light 17 optical member 18 optical axis of imaging optical system 19 side surface of optical member 20 circumscribed circle 21 of imaging element 21 joining surface 22 Portion of the light-receiving surface that is not in contact with the cover glass 23 Exit pupil of the imaging optical system 24 Most peripheral chief ray in the field of view 25 Angle of the image output area 31 First lens 32 Laser cut interference filter 33 Second lens 34 Color correction Absorption filter 35 Third lens 36 Optical member 37 Cover glass 38 Lens frame 39 CCD frame 41 Spacing ring 40, 43 Flare stop 42 Brightness stop 44 CCD 45 Image side surface of CCD frame 46 Object side surface of four corners 47 Adhesive 48 chip 49, 50, 51 optical member 52 gap 53 adhesive

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C061 AA00 BB00 CC06 DD00 FF40 JJ06 JJ11 LL02 NN01 5C022 AA09 AC42 AC54 AC55 AC56 AC63 5C024 BA03 CA02 FA01 GA11

Claims (6)

[Claims] 1. An image pickup apparatus comprising an image pickup optical system and an image pickup device, wherein an image side of an object side of a cover glass of the image pickup device is provided.
An imaging apparatus, wherein an optical member having an outer dimension larger than that of the cover glass is arranged adjacent to at least one opposite side of an image display area of a light receiving surface of the imaging element. 2. The imaging apparatus according to claim 1, wherein the thickness of the optical member is equal to or less than the thickness of the cover glass. 3. The imaging apparatus according to claim 1, wherein an outer diameter of the optical member is equal to or less than an outer diameter of a circumcircle of the cover glass or equal to or less than an outer diameter of a circumcircle of the imaging element. 4. The imaging apparatus according to claim 1, wherein the following expression (3) or (4) is satisfied. T ≧ 0.0002 · n / (2 · P · tan (1 / 2Fno)) (3) T ≧ 0.001 / P (4) where T is the optical member and the optical member. The total thickness of the cover glass, n is the refractive index of the optical member, Fno is the F number of the imaging optical system, and P is the pixel pitch of the imaging device. 5. The imaging apparatus according to claim 4, wherein the following expression (6) is satisfied in a direction in which the numerical value obtained by the following expression (5) is minimum. LAS-IH (5) sinθ ≦ n (LAS-IH) / √ (T ² + (LAS-IH) ² ) (6) where LAS is measured from the optical axis of the imaging optical system. The distance to the side surface of the optical member, IH is the distance from the optical axis of the imaging optical system to the corner of the image output area, and θ is the optical axis of the principal ray going to the corner of the image output area and entering the optical member. The angle, n indicates the refractive index of the optical member, and T indicates the total length of the optical member and the cover glass. 6. The optical member and the cover glass are bonded to each other, a center of the optical member substantially coincides with a center of an image output area of the image sensor, and the adhesive is an ultraviolet-curing type or an ultraviolet-curing adhesive. The imaging apparatus according to claim 1, wherein the imaging apparatus is a combination type of a thermosetting and a thermosetting, and satisfies the following expressions (7) and (8). Ng <1.6 .. (7) | Ng-Nc | <0.1 .. (8) where Ng is the refractive index of the optical member or the cover glass, and Nc is the adhesive. Indicates the refractive index.