JP2001208964A - Electronic image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic image pickup device capable of reducing a chromatic flare for a wide natural subject. SOLUTION: This device is provided with an electronic imaging device 1 including plural pixels having three or more different spectroscopic characteristics for obtaining a color image and an image pickup optical system 3 forming a subject image on the image pickup surface 2 of the device 1. The optical system 3 is constituted to satisfy a following conditional expression (1) assuming that a minimum F value is Fmin, and the absolute value of the spherical aberration amount of a marginal light beam on an h-line (404.7 nm) is Lh and the absolute value of the spherical aberration amount of the marginal light beam on a d-line (587.56 nm) is Ld when the F value is Fmin, and satisfy a following conditional expression (2) assuming that the transverse chromatic aberration amount on the h-line to the d-line when the image height ratio of maximum image height is 0.9, 0.7 and 0.5 is Sh. (1) (Lλ-Ld)/Fmin<=0.07 mm and (2) |Sh|<=0.04 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an imaging optical system for forming a subject image on an imaging surface of an electronic imaging device including a plurality of pixels having three or more different spectral characteristics for obtaining a color image such as a CCD. The present invention relates to an electronic imaging device having the same.

[0002]

2. Description of the Related Art In a conventional electronic image pickup apparatus using an electronic image pickup device, sensitivity from a short wavelength of visible light to an ultraviolet wavelength is ensured in order to secure the amount of light received by the electronic image pickup device. Further, when the amount of light received by the electronic image pickup device is weak or the like, the output may be higher than the ratio of the input to the photoelectric conversion device during image reproduction by controlling the gamma characteristic.

[0003]

However, when the energy at the wavelength near the h-line is large, the tint of the reproduced image becomes
There is a problem that the color is perceived as dark blue with respect to the color seen by the actual human eyes. This is because, despite the fact that the sensitivity of the human eye is fairly low on the short wavelength side of the visible range, electronic imaging devices have high sensitivity even in the short wavelength range, so short wavelengths are easily visible to the human eye. This is because it will be played back.

Further, in the design of an optical system, which has been conventionally performed with an emphasis on the intermediate wavelength region of the visible light region, chromatic aberration at both ends of the visible light region, particularly on the short wavelength side, cannot be completely corrected. Therefore, there is a problem that when a subject having a sharp difference in brightness is imaged, a strong blue color flare occurs at the boundary between the brightness and the darkness, in combination with the color enhancement of the short wavelength ahead.

Accordingly, the present invention has been made in view of the above problems,
An object of the present invention is to provide an electronic imaging device in which color flare is reduced for a wide range of natural subjects.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to correct the chromatic aberration of the h-line in the same manner as the chromatic aberration of the d-line. Thus, even if the h-line of the subject is reproduced at a blue wavelength that is easily recognized by the human eye, color flare in which blue is extremely conspicuous is removed by overlapping the reproduction with another wavelength. Specifically, the electronic imaging device according to the present invention forms an electronic imaging device including a plurality of pixels having three or more different spectral characteristics for obtaining a color image, and forms a subject image on an imaging surface of the electronic imaging device. The imaging optical system has a minimum F value of Fmin, the F value is Fmin, and the absolute value of the spherical aberration of the h-line (404.7 nm) marginal ray at the time of focusing on an object point at infinity. Where Lh is the absolute value of the spherical aberration of the marginal ray at the d-line (587.56 nm), Ld is satisfied, and the image height ratio of the maximum image height is 0.9, 0. When the lateral aberration of the magnification of the h-line with respect to the d-line at 0.7 and 0.5 is defined as Sh, the following conditional expression (2) is satisfied. (Lh−Ld) /Fmin≦0.07 mm (1) | Sh | ≦ 0.04 mm (2)

An electronic imaging device according to the present invention includes an electronic imaging device including a plurality of pixels having three or more different spectral characteristics for obtaining a color image, and an object image formed on an imaging surface of the electronic imaging device. An imaging optical system for forming, wherein the imaging optical system sets the minimum pitch of the pixels to P and the minimum F value to
Fmin, F-number is Fmin and h-line (40
The absolute value of the spherical aberration of the marginal ray of 4.7 nm) is Lh,
Assuming that the absolute value of the spherical aberration of the marginal ray at the d-line (587.56 nm) is Ld, the following conditional expression (3) is satisfied, and the image height ratio of the maximum image height is 0.9, 0.7, When the lateral aberration of the h-line magnification color with respect to the d-line at 0.5 is assumed to be Sh, the following conditional expression (4) is satisfied. (Lh−Ld) / Fmin ≦ 6P (3) | Sh | ≦ 5P (4)

Further, the present invention is preferably characterized in that the following conditional expressions (5) and (6) are satisfied in addition to the above configuration. (Lh−Ld) /Fmin≧0.5P (5) | Sh | ≧ 0.03P (6)

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a main part of a digital camera showing an embodiment of an electronic imaging apparatus according to the present invention. The electronic imaging device according to the present embodiment includes an electronic imaging device 1 including a plurality of pixels having three or more different spectral characteristics for obtaining a color image, and an imaging device that forms a subject image on an imaging surface 2 of the electronic imaging device. And an optical system 3.

The state of image formation at the center of the imaging surface 2 can be determined based on the spherical aberration diagram. FIG. 2 is a spherical aberration diagram of the imaging optical system of FIG. 1 when focusing on an object point at infinity. In FIG. 2, the F value when the aperture is fully opened, that is, the absolute value of the difference between the position where the marginal ray of each wavelength of the maximum incident height and the optical axis intersects the optical axis and the paraxial image point at the minimum F value Fmin, that is, the amount of spherical aberration The absolute value of
Lλ. If λ is the d line (587.56 nm), then d
If the absolute value of the spherical aberration of the line is Ld, and if λ is the h-line (404.7 nm), the absolute value of the spherical aberration of the h-line is expressed as Lh.

In the aberration diagram of FIG. 2, Ld and Lh indicate the amount of shift of the focal position at the maximum incident height, which is the center of the image plane of the image pickup optical system 3 in the electronic image pickup apparatus of FIG. FIG. 3 is a sectional view near the center of FIG. In FIG. 3, a solid line indicates a marginal ray having a maximum incident height of the d-line, and a broken line indicates a marginal ray having a maximum incident height of the h-line. The deviation of the image plane of each wavelength from the paraxial image plane 2 is recognized as a color flare on the paraxial image plane. In FIG. 3, the shift amounts (diameters) from the optical axis 4 on the paraxial image plane 2 are represented by Ld / Fmin and Lh / Fmin, respectively.

If the difference between Ld / Fmin and Lh / Fmin is large, color flare tends to occur. However, in order to suppress color flare on the shorter wavelength side than the d-line, the difference between Ld / Fmin and Lh / Fmin is reduced. Is not more than 0.07 mm, that is, the following conditional expression (1) (Lh−Ld) /Fmin≦0.07 mm (1) is satisfied.

According to this structure, the color shift between the light near the h-line and the light near the d-line, which causes color flare, is suppressed, so that the color shift on the short wavelength side can be suppressed and reproduced. Color flare can be suppressed. Ld / Fmi
When the difference between n and Lh / Fmin exceeds the upper limit of the conditional expression (1), the color flare becomes conspicuous.

Although the chromatic aberration on the optical axis has been described above, the same applies to the chromatic aberration of magnification. FIG. 4 is an aberration diagram showing chromatic aberration at the magnification of the h-line with respect to the d-line. FIG.
, The image height ratio of the maximum image height to the maximum image height IH is 0.1.
Arrows indicate the lateral aberration amount Sh of the magnification color of the h line with respect to the d line at 9, 0.7, and 0.5. When this is expressed on the paraxial image plane 2 in FIG. 1, the image height ratio on the image plane is 0.9, 0.7,
The state of the chromatic aberration at 0.5 is as shown in FIG. 5, and the lateral aberration amount S of the magnification color, which is the difference between the principal rays of the d line and the h line.
h is recognized as a color flare, but the color flare can be suppressed by setting the shift amount | Sh | to 0.04 mm or less at each image height ratio, that is, satisfying the following conditional expression (2). | Sh | ≦ 0.04 mm (2) If the shift amount | Sh | exceeds the upper limit of the conditional expression (2), chromatic aberration of magnification occurs, and color flare becomes conspicuous.

In the electronic imaging device according to the present embodiment,
It was configured such that the above conditional expressions (1) and (2) were simultaneously satisfied.
This makes it possible to suppress color misregistration in the entire area on the image plane, and to reproduce a good image with inconspicuous color misregistration even for a subject having a sharp difference in brightness.

In this embodiment, the above conditional expression
When the upper limit of (1) is 0.05 mm, and more preferably 0.03 mm, a better image can be obtained.

The upper limit of condition (2) is set to 0.03
mm, and more preferably 0.02 mm, a better image can be obtained.

In the electronic imaging device 1, a plurality of pixels are arranged in a matrix. When the minimum pitch of each pixel is P, the above conditional expression (1) is replaced by the following conditional expression (3). To
Even if the above conditional expression (2) is replaced with the following conditional expression (4), the color shift can be similarly suppressed in the entire area on the image plane, and the color misregistration is conspicuous even for a subject with a sharp contrast. No good image can be reproduced. (Lh−Ld) / Fmin ≦ 6P (3) | Sh | ≦ 5P (4)

If the difference between Ld / Fmin and Lh / Fmin exceeds the upper limit of conditional expression (3), or if the deviation | Sh | exceeds the upper limit of conditional expression (4), color flare becomes conspicuous. Become like If the upper limit of conditional expression (3) is 4P, more preferably 2P, a better image can be obtained.

Further, when the upper limit of conditional expression (4) is set to 3P, more preferably 2P, a better image can be obtained.

On the other hand, there is an area between the pixels of the electronic image pickup device 1 where light cannot be received. There is also a technique for improving the light reception rate by providing a micro lens corresponding to each pixel, but the area used for light reception with respect to the imaging area is 40%.
~ 80%. Therefore, even if a certain amount of chromatic aberration appears, it does not affect the reproduced image. Also, considering the influence of excessive correction of each chromatic aberration on other aberrations, the following conditional expression (5)
It is preferable to satisfy the condition (6). (Lh−Ld) /Fmin≧0.5P (5) | Sh | ≧ 0.03P (6) Even if the correction exceeds the lower limits of the conditional expressions (5) and (6), While there is no effect of chromatic aberration on the reproduced image, it is rather difficult to correct other aberrations. Sh is the lateral aberration of the magnification color of the h-line with respect to the d-line at any one of the image height ratios of the maximum image height of 0.9, 0.7, and 0.5.

Next, the structure and operation of an image pickup optical system that is preferable for achieving the structure of the electronic image pickup apparatus of the present embodiment will be described. The imaging optical system 3 in FIG. 1 has a stop S, and among the lens configurations on the image side with respect to the stop S, 3
It is good to make a sheet into a negative lens, a positive lens, and a positive lens in order. Further, it is preferable that the negative lens and the image-side positive lens are joined.

The imaging optical system according to the present embodiment comprises a positive lens, a positive lens, and a negative lens in order from the object side among the lenses on the image side of the stop, and further includes an image of the three lenses. The positive lens group may be arranged on the side. Further, it is preferable that the positive lens on the image side of the positive lens and the negative lens are cemented.

The imaging optical system according to the present embodiment includes, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a diaphragm, and a positive refractive power. A third lens unit having a third lens unit and a fourth lens unit having a positive refractive power;
The group may be composed of one or two positive lenses and negative lenses in order from the object side. Further, it is preferable that the third group includes a cemented lens including one positive lens and one negative lens.

Further, some of the positive lenses in the third and subsequent groups have anomalous dispersion ΔθgF> 0.0 for g-line and F-line.
25 glass material was added to the negative lens and the anomalous dispersion ΔθgF <0.
No. 01 glass material may be used. More preferably, the anomalous dispersion ΔθgF of the positive lens is 0.027 or more, or the anomalous dispersion ΔθgF of the negative lens is 0.008 or less.

The imaging optical system of this embodiment includes, in order from the object side, a front group having a negative meniscus lens having a convex surface facing the object side, an aperture, and a rear group having a positive refractive power. It is preferable that the rear group has at least one aspherical surface and at least one positive lens satisfying the following conditional expressions (7) and (8). ΔθgF (r)> 0.025 (7) −0.5 <(R1 + R2) / (R1−R2) <0.5 (8) However, ΔθgF (r) is at least 1 in the rear group. The anomalous dispersion of the media of the positive lenses, R1 and R2, are respectively
The paraxial radius of curvature of the object side and the image side of at least one positive lens in the rear group.

With the positive lens, as the angle of view increases,
While the chromatic aberration of magnification at the g-line rapidly increases to a large positive value, the axial chromatic aberration at the g-line also tends to have a large positive value. In particular, in this type of positive lens, the spherical aberration of the g-line tends to take a positive value toward the outside of the aperture, and flare having a short wavelength equal to or less than the g-line tends to occur. Therefore, in order to suppress both the chromatic aberration of magnification of the g-line and the axial chromatic aberration from becoming large positive values, a positive lens in the rear group, which is located slightly away from the aperture, and has a certain amount of axial ray height. It is preferable to use a medium that satisfies the conditional expression (7). When the anomalous dispersion ΔθgF (r) of the medium of the positive lens exceeds the lower limit of the conditional expression (7), it becomes difficult to correct chromatic aberration.

The positive lens in the rear group, which is located slightly away from the stop, and has a certain axial ray height,
Since the angle of the light beam is generally small, it is preferable to use a biconvex lens that satisfies the conditional expression (8) and that has a curvature radius on both surfaces that is close to each other, in order to correct the chromatic aberration. If the curvature radii R1 and R2 of both surfaces exceed the range of the conditional expression (8), short-wavelength color flare tends to occur, which is not preferable.

Further, in the image pickup optical system of the present embodiment, the positive lens made of a medium having a refractive index higher than the refractive index of the medium of the at least one positive lens in the rear group with respect to d-line by 0.17 or more is provided. It is preferable to have it in a group. Further, it is preferable that the difference in the refractive index between these positive lenses is 0.22 or more.

A medium having a high Abbe number and a large anomalous dispersion that satisfies the conditional expression (7) tends to have a low refractive index, for example, 1.4 to 1.5. is there. In this case, since it is difficult to correct spherical aberration and field curvature, it is necessary to use a medium having a high refractive index as described above for other convex lenses in the rear group. When the refractive index of the convex lens exceeds the lower limit of 0.17, it becomes difficult to correct spherical aberration and field curvature.

In order to correct chromatic aberration with a small number of lenses, it is preferable that the rear unit is composed of a cemented lens component of a negative lens and a positive lens, and a positive lens in order from the object side.

In order to perform correction including various aberrations, it is preferable that the front unit is composed of two lenses, a positive lens and a negative meniscus lens, in order from the object side.

In order to correct chromatic aberration with the four-unit zoom lens, the image pickup optical system is moved from the object side in order from the first group having a positive refractive power to the first group having a negative refractive power during zooming. A second group, a stop, and a third group having a positive refractive power;
4th that has positive refractive power and moves during zooming and focusing
It is preferable that the fourth lens unit includes at least one positive lens that has at least one aspheric surface and satisfies the following conditional expressions (9) and (10). ΔθgF (4)> 0.025 (9) −0.5 <(R14 + R24) / (R14−R24) <0.5 (10) However, ΔθgF (4) is at least one of the fourth group. The anomalous dispersion of the medium of one positive lens, R14 and R24, are the paraxial radius of curvature of the object side and the image side of at least one positive lens in the fourth group, respectively. If the anomalous dispersion ΔθgF (4) of the medium of the positive lens exceeds the lower limit of the conditional expression (9), it becomes difficult to correct chromatic aberration. Also, the radius of curvature R of both surfaces
When R14 and R24 exceed the range of the conditional expression (10), short-wavelength color flare tends to occur, which is not preferable.

Further, the imaging optical system of the present embodiment includes a positive lens made of a medium having a refractive index higher than that of the medium of at least one positive lens in the fourth group by 0.17 or more with respect to the d-line. It is preferable to adopt a configuration provided in the third and subsequent groups. Further, it is preferable that the difference in the refractive index between these positive lenses is 0.22 or more.

In the image pickup optical system of the present embodiment, the lens system on the image side of the stop is composed of a positive lens, a cemented lens component of a positive lens and a negative lens, and a positive lens in order from the object side. However, it is preferable for miniaturizing the imaging optical system and correcting chromatic aberration.

Next, a description will be given of a color filter used for an electronic image pickup device arranged near an object image by the image pickup optical system. In order to obtain a color image, a color filter as shown in FIGS. 6 and 7 is arranged in an electronic imaging device in which a plurality of pixels (photoelectric conversion devices) having three or more different spectral characteristics are arranged at a pixel pitch P.

FIG. 6 is a schematic structural view of a type of color filter called a primary color filter. The primary color filters include red (R), green (G), and blue (B) filters. FIG. 7 shows the wavelength characteristics of each filter. FIG. 8 is a schematic configuration diagram of a type of color filter called a complementary color filter. The complementary color filter is composed of cyan (C), magenta (M), yellow (Ye), and green (G) filters. In addition,
FIG. 9 shows the spectral characteristics of each filter.

Hereinafter, the present invention will be described in detail based on embodiments using numerical data. First Embodiment FIG. 10 is a cross-sectional view along the optical axis showing a lens configuration of a first embodiment of an electronic imaging apparatus according to the present invention.
(b) shows the state at the middle, and (c) shows the state at the telephoto end. FIG. 11 shows the first
It is a figure showing spherical aberration, astigmatism, distortion, and chromatic aberration in an example.

The electronic imaging apparatus of this embodiment includes an electronic imaging device 1 including a plurality of pixels having three or more different spectral characteristics for obtaining a color image, and a subject image on an imaging surface 2 of the electronic imaging device. And an imaging optical system 3 to be formed. The imaging optical system 3 includes, in order from the object side, a first group G1 having a positive refractive power, a second group G2 having a negative refractive power and moving at the time of zooming, a stop S, and a positive refractive power. The zoom lens includes a third lens group G3 that moves during zooming and a fourth lens group G4 that has a positive refractive power and moves during zooming and focusing. The third lens unit G3 located on the image side of the stop S is arranged in order from the object side.
Positive lens G3 _1, the positive lens G3 _2, and a negative lens G3 ₃ Prefecture. Further, the positive lens G3 ₂ and the negative lens G3 ₃
Are joined together. The fourth group G4 includes a biconvex lens having an aspheric surface on the object side. For zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed,
The second lens group G2 to the fourth lens group G4 are respectively moved on the optical axis, and focusing is performed by moving the fourth lens group G4 on the optical axis. In the figure,
L ₁ is an optical low-pass filter, L ₂ is an infrared cut filter, and L ₃ is a cover glass of the electronic imaging device 1.

Next, numerical data of optical members constituting the electronic imaging apparatus according to the present embodiment will be shown. In the numerical data of this embodiment, ω is the half angle of view, r ₁ , r ₂ ,... Are the radii of curvature of the respective lens surfaces, d ₁ , d ₂ ,... Are the thicknesses or air intervals of the lenses, ΔθgF ₁ , ΔθgF. _2, ... it is anomalous dispersion medium of each lens, nd _1, nd _2, ... is the refractive index at the d-line of each lens,
ν ₁ , ν ₂ ,... are Abbe numbers of the lenses, and nh ₁ , nh ₂ ,. The aspheric shape is
The optical axis direction Z, taking the y in a direction orthogonal to the optical axis, the conical coefficient k, aspherical coefficients _{AC 2, AC 4, AC 6} , AC 8, A
When C _{10 and} AC ₁₂ are set, they are expressed by the following equations. Z = (y ² / r) / [1+ ｛1− (1 + k) · (y /
r) ² ｝ ^1/2 ] + AC ₂ y ² + AC ₄ y ⁴ + AC ₆ y ⁶ + AC ₈
y ⁸ + AC ₁₀ y ¹⁰ + AC ₁₂ y ¹² These symbols are common to the numerical data of the embodiments described later.

Numerical data 1 Focal length f = 6.5-10.96-19.5 (mm) F value 2.0-2.3-2.9 Half angle of view ω = 33-21-12 (°) r ₁ = 39.6531 d ₁ = 4.1900 ΔθgF ₁ = 0.0386 nd ₁ = 1.45600 ν ₁ = 90.33 nh ₁ = 1.46441 r ₂ = -753.3169 d ₂ = (variable) r ₃ = 22.5664 d ₃ = 1.2500 ΔθgF ₃ = 0.0174 nd ₃ = 1.84666 ν ₃ = 23.78 nh ₃ = 1.91428 r ₄ = _{7.9565 d 4 = 5.4000 r 5 =} -28.6765 d 5 = 1.0000 ΔθgF 5 = -0.0005 nd 5 = 1.51823 ν 5 = 58.90 nh 5 = 1.53315 r 6 = 10.2176 d 6 = 4.5200 ΔθgF 6 = 0.0174 nd 6 = 1.84666 ν 6 = 23.78 nh ₆ = 1.91428 r ₇ = 52.1549 d ₇ = (variable) r ₈ = ∞ (aperture) d ₈ = (variable) r ₉ = 20.6797 (aspherical surface) d ₉ = 3.3600 ΔθgF ₉ = 0.0023 nd ₉ = 1.58913 ν ₉ = 61.25 nh ₉ = 1.60531 r ₁₀ = -25.0033 d ₁₀ = 0.2000 r ₁₁ = 9.0354 d ₁₁ = 4.5000 ΔθgF ₁₁ = −0.0096 nd ₁₁ = 1.74100 ν ₁₁ = 52.64 nh ₁₁ = 1.76491 r ₁₂ = 215.0441 d ₁₂ = 0.9000 Δθ gF ₁₂ = 0.0075 nd ₁₂ = 1.80518 ν ₁₂ = 25.46 nh ₁₂ = 1.86430 r ₁₃ = 6.3536 d ₁₃ = (variable) r ₁₄ = 15.4926 (aspherical surface) d ₁₄ = 3.2200 ΔθgF ₁₄ = 0.0280 nd ₁₄ = 1.49700 ν ₁₄ = 81.54 nh ₁₄ = 1.50720 r ₁₅ = -23.1797 d ₁₅ = (variable ) R ₁₆ = ∞ d ₁₆ = 0.8000 ΔθgF ₁₆ = -0.0024 nd ₁₆ = 1.51633 ν ₁₆ = 64.14 nh ₁₆ = 1.52977 r ₁₇ = ∞ d ₁₇ = 1.8000 ΔθgF ₁₇ = -0.0045 nd ₁₇ = 1.54771 ν ₁₇ = 62.84 nh ₁₇ = 1.56226 r ₁₈ = ∞ d ₁₈ = 0.8000 r ₁₉ = ∞ d ₁₉ = 0.7500 ΔθgF ₁₉ = -0.0024 nd ₁₉ = 1.51633 ν ₁₉ = 64.14 nh ₁₉ = 1.52977 r ₂₀ = ∞ d ₂₀ = (variable) Electronic imaging device (image plane) ) ∞

Aspheric coefficient ninth surface k = 0 AC ₂ = 0.0000 × 10 ⁰ , AC ₄ = −6.2681 × 10 ⁻⁵ , AC ₆ = 2.5583 × 10 ⁻⁷ AC ₈ = −3.6774 × 10 ⁻⁸ , AC ₁₀ = 1.8093 × 10 ^-9 , AC ₁₂ = -2.8329 × 10 ^-11 Surface 14 k = 0 AC ₂ = 0.0000 × 10 ⁰ , AC ₄ = -7.6728 × 10 ^-5 , AC ₆ = -3.6402 × 10 ^-6 AC ₈ = 6.1375 x 10 ^-7 , AC ₁₀ = -3.5417 x 10 ^-8 , AC ₁₂ = 7.0508 x 10 ^-10

[0043] Zoom data wide-angle end Intermediate Telephoto end _{d 0 = ∞ ∞ ∞ d 2} = 1.00000 10.95361 15.77923 d 7 = 16.29024 6.33662 1.51100 d 8 = 8.57300 6.78687 1.49700 d 13 = 3.56500 3.36931 5.12785 d 15 = 3.16176 5.14358 8.67492 d 20 = 1.11946 1.11936 1.11885

Conditional Expressions (7), (8), (9), (10) ΔθgF (r) = ΔθgF (4) = ΔθgF ₁₄ = 0.0280 (R1 + R2) / (R1−R2) = (R14 + R24) / (R14 −R24) = (r ₁₄ + r ₁₅ ) / (r ₁₄ -r ₁₅ ) = {15.4926 + (-23.1797)} / {15.4926-(-23.1797)}｝-1.9877 The refractive index difference between the positive lenses for the d-line nd ₁₁ -nd ₁₄ = 1.74100-1.49700 = 0.244 (Lh−Ld) / Fmin Wide-angle end Medium Telephoto end 0.060919 0.053495 0.059700 h for d-line at image height ratio of 0.9, 0.7, 0.5 at maximum image height Lateral aberration of line magnification color Sh Image height ratio Wide-angle end Medium Telephoto end 0.9x 0.010516 (mm) 0.010123 (mm) 0.000658 (mm) 0.7x 0.002456 (mm) 0.004998 (mm) 0.000839 (mm) 0.5x 0.001354 ( mm) 0.002167 (mm) 0.000775 (mm) Pixel pitch P 0.033 (mm)

Second Embodiment FIG. 12 is a sectional view taken along the optical axis showing a lens configuration of a second embodiment of the electronic image pickup apparatus according to the present invention. FIG. 13 is a diagram showing spherical aberration, astigmatism, and distortion in the second embodiment. And FIG.

The electronic image pickup apparatus of this embodiment includes an electronic image pickup device 1 including a plurality of pixels having three or more different spectral characteristics for obtaining a color image, and an image of a subject on an image pickup surface 2 of the electronic image pickup device. And an imaging optical system 3 to be formed. The imaging optical system 3 includes, in order from the object side, a first group G1 having a positive refractive power, a second group G2 having a negative refractive power, and a stop S
And a third group G3 having a positive refractive power and a fourth group G4 having a positive refractive power. First group G1
Is composed of one positive lens, and the second group G2 is composed of one negative meniscus lens. A third lens located on the image side of the stop S
Group G3 includes, in order from the object side, a negative lens G3 _1, the positive lens G3 ₂ Prefecture. The negative lens G3 ₁ and the positive lens G3 ₂ are joined together. The fourth group G4 includes a biconvex lens having an aspheric surface on the object side. The focusing is performed by moving the first lens group G1 to the fourth lens group G4 on the optical axis while maintaining the relative positions. In the figure, L ₁ is an optical low-pass filter, L ₂ is an infrared cut filter, and L ₃ is an electronic imaging device 1.
Is a cover glass.

Next, numerical data of optical members constituting the electronic imaging apparatus according to the present embodiment will be shown. Numerical data 2 Focal length f = 5 (mm) F value 2.8 Half angle of view ω = 31 (°) r ₁ = 14.3151 d ₁ = 2.3000 ΔθgF ₁ = 0.0158 nd ₁ = 1.80518 ν ₁ = 25.42 nh ₁ = 1.86494 r ₂ = 89.2153 d ₂ = 0.2500 r ₃ = 9.1137 d ₃ = 0.7500 ΔθgF ₃ = 0.0280 nd ₃ = 1.49700 ν ₃ = 81.54 nh ₃ = 1.50720 r ₄ = 2.6148 d ₄ = 3.7697 r ₅ = ∞ (aperture) d ₅ = 1.1000 r ₆ = -7.9912 d ₆ = 0.8000 ΔθgF ₆ = 0.0075 nd ₆ = 1.80518 ν ₆ = 25.46 nh ₆ = 1.86430 r ₇ = 15.0577 d ₇ = 3.5000 Δθ gF ₇ = -0.0086 nd ₆ = 1.72916 ν ₆ = 54.68 nh ₆ = 1.75173 r _{8 = -5.5506 d 8 = 0.1500 r 9} = 9.6764 ( _{aspherical) d 9 = 3.6000 ΔθgF 9 =} 0.0280 nd 9 = 1.49700 ν 9 = 81.54 nh 9 = 1.50720 r 10 = -8.2960 d 10 = 1.5000 r 11 = ∞ d 11 = 1.6000 ΔθgF ₁₁ = -0.0024 nd ₁₁ = 1.51633 ν ₁₁ = 64.15 nh ₁₁ = 1.52977 r ₁₂ = ∞ d ₁₂ = 2.0200 Δθ gF ₁₂ = -0.0024 nd ₁₂ = 1.51633 ν ₁₂ = 64.15 nh ₁₂ = 1.52977 r ₁₃ = ∞ d ₁₃ = 1.6000 r ₁₄ = ∞ d ₁₄ = 0.7500 ΔθgF _{14 = 0.0022 nd 14 = 1.48749 ν} 14 = 70.21 nh 14 = 1.49898 r 15 = ∞ d 15 = 1.1866 electronic imaging device (image surface) ∞

Aspheric coefficient ninth surface k = 0 AC ₂ = 0.0000 × 10 ⁰ , AC ₄ = −7.1869 × 10 ⁻⁴ , AC ₆ = −1.4974 × 10 ⁻⁵ AC ₈ = 1.8101 × 10 ⁻⁶ , AC ₁₀ = -7.6598 × 10 ^-8

Conditional Expressions (7) and (8) ΔθgF (r) = ΔθgF ₉ = 0.0280 (R1 + R2) / (R1-R2) = (r ₉ + r ₁₀ ) / (r ₉ -r ₁₀ ) = ｛9.6764+ (-8.2960)｝ / ｛9.6764-(-8.2960)｝ ≒ -0.07681 Difference in refractive index between the positive lens and d-line nd ₇ -nd ₉ = 1.72916-1.49700 ≒ 0.232 (Lh-Ld) / Fmin 0.024384 (mm) Maximum The lateral aberration amount of the h-line magnification color with respect to the d-line at the image height ratio of 0.9, 0.7 and 0.5 Sh Image height ratio Sh 0.9x 0.017038 (mm) 0.7x 0.000308 (mm) 0.5x 0.004529 (mm) Pixel pitch P 0.033 (mm)

As described above, the electronic imaging apparatus according to the present invention has the following features in addition to the features described in the claims.

(1) The electronic imaging apparatus according to claim 1, wherein the conditional expression (1) is replaced by the following conditional expression (1 '). (Lh-Ld) / Fmin ≤0.05mm ... (1 ')

(2) The electronic imaging apparatus according to claim 1, wherein the conditional expression (1) is replaced by the following conditional expression (1 ''). (Lh-Ld) / Fmin ≤ 0.03mm ... (1 '')

(3) The electronic imaging apparatus according to claim 1, wherein the conditional expression (2) is replaced by the following conditional expression (2 '). | Sh | ≦ 0.03 mm ...... (2 ')

(4) The electronic imaging apparatus according to claim 1, wherein the conditional expression (2) is replaced by the following conditional expression (2 ''). | Sh | ≦ 0.02mm …… (2 '')

(5) The imaging optical system has a stop, and among the lens arrangement on the image side of the stop, three lenses from the object side are a negative lens, a positive lens, and a positive lens in this order. The electronic imaging device according to claim 1.

(6) The electronic imaging device according to (5), wherein the negative lens and the positive lens on the object side are cemented.

(7) The imaging optical system has a stop, and among the lenses on the image side of the stop, three lenses from the object side are sequentially arranged.
3. The electronic imaging apparatus according to claim 1, wherein a positive lens group is disposed on an image side of the three lenses, the lens group being a positive lens, a positive lens, and a negative lens.

(8) The electronic imaging apparatus according to (7), wherein the positive lens on the image side of the positive lens and the negative lens are cemented.

(9) In order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a stop, a third lens unit having a positive refractive power, and a positive refractive power 3. The fourth group according to claim 1, wherein the third group includes, in order from the object side, two or less positive lenses and negative lenses. 4. Electronic imaging device.

(10) The third group is composed of one positive lens and one
(9) The electronic imaging device according to (9), further including a cemented lens including a negative lens.

(11) A glass material having an anomalous dispersion ΔθgF> 0.027 is used for a part of the positive lenses of the third or fourth group, and a glass material having an anomalous dispersion ΔθgF <0.01 is used for a negative lens. The electronic imaging device according to the above (9), wherein:

(12) The imaging optical system includes, in order from the object side, a front group having a negative meniscus lens having a convex surface facing the object side, a stop, and a rear group having a positive refractive power.
The said rear group has at least one positive lens which has at least one aspheric surface and which satisfies the following conditional expressions (7) and (8). The electronic imaging device according to any one of 4). ΔθgF (r)> 0.025 (7) −0.5 <(R1 + R2) / (R1−R2) <0.5 (8) However, ΔθgF (r) is at least 1 in the rear group. The anomalous dispersion of the media of the positive lenses, R1 and R2, are respectively
The paraxial radius of curvature of the object side and the image side of at least one positive lens in the rear group.

(13) A positive lens made of a medium having a refractive index higher than that of the at least one positive lens medium in the rear group by 0.17 or more with respect to d-line is provided in the rear group. The electronic imaging device according to the above (12).

(14) The electronic imaging apparatus according to the above (12) or (13), wherein the rear group includes, in order from the object side, a cemented lens component of a negative lens and a positive lens, and a positive lens.

(15) The electronic imaging apparatus according to any one of (12) to (14), wherein the front group includes two lenses, a positive lens and a negative meniscus lens, in order from the object side.

(16) The imaging optical system includes, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and moving at the time of zooming, a stop, and a positive lens. The zoom lens includes a third lens unit having a refractive power and a fourth lens unit having a positive refractive power and moving at the time of zooming and focusing. The fourth lens unit has at least one aspherical surface. And the following conditional expressions (9) and (10)
2. At least one positive lens satisfying the following condition:
To 3, and the electronic imaging device according to any one of (1) to (4). ΔθgF (4)> 0.025 (9) −0.5 <(R14 + R24) / (R14−R24) <0.5 (10) However, ΔθgF (4) is at least one of the fourth group. The anomalous dispersion of the medium of one positive lens, R14 and R24, are the paraxial radius of curvature of the object side and the image side of at least one positive lens in the fourth group, respectively.

(17) The at least one of the fourth group
0.17 than the refractive index of the positive lens medium for d-line
The electronic imaging device according to (16), further including a positive lens made of a medium having a high refractive index in the third and subsequent groups.

(19) The lens system on the image side of the stop is
(12) comprising, in order from the object side, a positive lens, a cemented lens component of a positive lens and a negative lens, and a positive lens;
(13) The electronic imaging device according to any one of (16) and (17).

[0069]

As described above, according to the present invention, it is possible to provide an electronic image pickup apparatus capable of reproducing a good image with suppressed color flare for a wide range of natural subjects.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of an imaging optical system showing an embodiment of an electronic imaging device of the present invention.

FIG. 2 is a spherical aberration diagram of the imaging optical system of FIG. 1;

FIG. 3 is a state explanatory diagram showing a shift amount of a focal position at a maximum incident height when viewed in a cross-sectional view at the center of an image plane in the imaging optical system of FIG.

4 is an aberration diagram showing chromatic aberration of magnification of an h-line with respect to a d-line in the imaging optical system of FIG. 1;

FIG. 5 is a diagram showing an image height ratio of 0 on the image plane in the imaging optical system of FIG.
FIG. 9 is a diagram illustrating the state of chromatic aberration at 9, 0.7, and 0.5 on a paraxial image plane.

FIG. 6 is a schematic configuration diagram of a primary color filter used in the electronic imaging device of the present invention.

FIG. 7 is a schematic configuration diagram of a complementary color filter used in the electronic imaging device of the present invention.

8 is a wavelength characteristic diagram of the primary color filter of FIG.

FIG. 9 is a spectral characteristic diagram of the complementary color filter of FIG. 7;

FIGS. 10A and 10B are cross-sectional views along the optical axis showing a lens configuration of a first embodiment of an electronic imaging apparatus according to the present invention. FIG. 10A is a view at a wide-angle end, FIG. Indicates the status.

11A and 11B are diagrams showing spherical aberration, astigmatism, distortion, and chromatic aberration in the first example, where FIG. 11A shows a state at a wide-angle end, FIG. 11B shows a state at a middle end, and FIG. .

FIG. 12 is a sectional view along an optical axis showing a lens configuration of a second embodiment of the electronic imaging apparatus according to the present invention.

FIG. 13 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration in the second example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electronic imaging element 2 (paraxial) image plane 3 imaging optical system 4 (paraxial) optical axis on image plane 2 G1 first group G2 second group G3 third group G4 fourth group S aperture

Continued on the front page (72) Inventor Masahiro Imamura 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industrial Co., Ltd. (72) Inventor Naoshi Goto 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical F-term (reference) in Kogyo Co., Ltd. 5C022 AA00 AB66 AC42 AC54 AC56 5C065 BB48 CC01 DD02 EE06 EE07 EE12 EE14 EE16 9A001 HH31 KK16 KK42

Claims (3)

[Claims] An electronic imaging device including a plurality of pixels having three or more different spectral characteristics for obtaining a color image, and an imaging optical system for forming a subject image on an imaging surface of the electronic imaging device. The imaging optical system sets the minimum F value to Fmin, sets the F value to Fmin, and sets the absolute value of the spherical aberration of the h-line (404.7 nm) marginal ray at the time of focusing on an object point at infinity to Lh and d-line ( When the absolute value of the spherical aberration of the marginal ray at 587.56 nm) is Ld, the following conditional expression (1) is satisfied, and the image height ratio of the maximum image height is 0.9, 0.7, 0.5. When the lateral aberration amount of the magnification color of the h line with respect to the d line in
An electronic imaging apparatus characterized by satisfying the following conditional expression (2). (Lh−Ld) /Fmin≦0.07 mm (1) | Sh | ≦ 0.04 mm (2) 2. An electronic imaging device including a plurality of pixels having three or more different spectral characteristics for obtaining a color image, and an imaging optical system for forming a subject image on an imaging surface of the electronic imaging device. The imaging optical system sets the minimum pitch of the pixels to P, sets the minimum F value to Fmin, and sets the minimum F value to Fmin and the spherical aberration of the h-line (404.7 nm) of the h-line (404.7 nm) when focusing on an object point at infinity. Absolute value L
Assuming that the absolute value of the spherical aberration amount of the marginal ray at the h and d lines (587.56 nm) is Ld, the following conditional expression (3) is satisfied, and the image height ratio of the maximum image height is 0.9, 0. Assuming that the lateral aberration amount of the magnification color of the h line with respect to the d line at 7 and 0.5 is Sh,
An electronic imaging apparatus characterized by satisfying the following conditional expression (4). (Lh−Ld) / Fmin ≦ 6P (3) | Sh | ≦ 5P (4) 3. The electronic imaging apparatus according to claim 2, wherein the following conditional expressions (5) and (6) are satisfied. (Lh−Ld) /Fmin≧0.5P (5) | Sh | ≧ 0.03P (6)