JPH05103271A - Image pickup device - Google Patents

Abstract

PURPOSE:To validly display a picture at a high-vision television or the like by providing a rotary asymmetrical refracted face in an objective lens, and transforming an image by a signal processing means. CONSTITUTION:This device is equipped with an objective lens 2 which forms the image of an object, solid image pickup element 1 which receives the image from the objective lens 2, signal processing means (sampling circuit 3, hold circuit 4, and video signal preparing circuit 5) which prepares an output signal from the image pickup element 1, and a display means (television monitor 6 and long sideway display part 7) which displays the image of the object from a video signal. Then, the objective lens 2 having the rotary asymmetrical refracted face expressed by an expression I, projects the transformed image of the object on the solid image pickup element 1, and the signal processing means 3-5 further transforms the transformed image, and displays it. In the expression I, (x)-(z) are the coordinate values of (x), (y) and (z) coordinates at the time of defining an optical axial direction as an (x)-axis, and the vertex of the screen as an origin. Therefore, the long sideway display part of the television monitor of the television with the high fidelity can be validly utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device for an electronic endoscope.

[0002]

2. Description of the Related Art In a conventional electronic endoscope, an object image is formed on a CCD 1 having a substantially square shape by a circular lens system 2 as shown in FIG. In many cases, the image 6 was displayed on the display unit 5.

In the current television system (NTSC system),
The aspect ratio of the display section 5 of the TV monitor is H: V =
4: 3. Therefore, even if the image 6 is displayed in a square shape on a part of the display unit 5 as shown in the figure, the television screen is rarely wasted.

However, the high-definition television has a display unit 7
Has an aspect ratio of H: V = 16: 9 and is horizontally long. Therefore, when considering an electronic endoscope for a high-definition television, displaying a square image by the electronic endoscope as shown in the figure on the horizontally long display portion results in a large waste of the display portion.

Although a horizontally long solid-state image pickup device may be used,
Arranging a horizontally long image pickup device in the endoscope undesirably increases the thickness of the endoscope.

[0006]

SUMMARY OF THE INVENTION The present invention provides an image pickup device for an electronic endoscope capable of observing a powerful image by effectively utilizing a horizontally long display portion of a television monitor of a high definition television. The purpose is.

[0007]

The image pickup device of the present invention comprises a solid-state image pickup element such as a CCD having a substantially square shape, an objective lens having an aspherical surface asymmetric with respect to the optical axis, and an electric expansion means. ing.

FIG. 1 is a view showing the arrangement of an image pickup device of the present invention. 1 is an image pickup device, 2 is an objective optical system, 3 is a sampling circuit, 4 is a hold circuit, 5 is a video signal producing circuit, and 6 is a television. A monitor, 7 is a horizontally long display, 8 is a light source, and 9 is a light guide.

Further, an aspherical lens which is not rotationally symmetric with respect to the optical axis is provided in the objective optical system, and an image of a substantially rectangular object is formed on the substantially square solid-state image pickup device 1.

The signal from the image pickup device 1 is read by the sampling circuit 3, and the image is expanded in the horizontal direction by making the reading speed in the horizontal direction (the horizontal scanning direction of the CCD) slower than usual.

B _v is the vertical dimension of the object, B _H is the horizontal dimension of the object, C _V is the vertical dimension of CCD 1,
When C _H is the horizontal dimension of the CCD 1, N _H is the number of horizontal pixels of the CCD 1, and N _V is the number of vertical pixels of the CCD 1, the object is represented by the following formula (1) by the objective optical system 2. The image is contracted by a factor of 2 and imaged on the CCD 1. (C _H / B _H ) / (C _V / B _V ) ≡k (1) where C _v / C _H > V / H. Therefore, the reading speed of the CCD 1 may be reduced by 1 / k times.

The horizontal scanning time of a high definition television is set to T _H (≈3
3μs), aspect ratio of high-definition TV is A (≒ 16/9)
If the vertical pixels of the CCD 1 correspond to the N _V scanning lines on the display unit 7 on the television monitor 6, there is no horizontal expansion. In other words, if you use normal CCD1,
The readout time interval t _H of the CCD pixel is calculated by the following equation (2).
Given in. _{t H ≒ N V / N HD} · C H / C V · 1 / A · T H / N H (2) provided that the horizontal blanking period of the vertical scanning assumed that the sufficiently small.

Here, N _HD is the number of vertical scanning lines of a high definition television, which is 1.125 in Japan.

Therefore, the CCD has 1 / k · t _H per pixel.
If read out at intervals, an image expanded by k times in the horizontal direction can be obtained.

The signal sampled by the sampling circuit 3 is held by the hold circuit 4 and is displayed on the display unit 7 as a luminance signal and a color difference signal by the video signal producing circuit 5.

FIG. 2 shows another example for enlarging a picked-up image in one direction by k times to 1 / k times.

The image taken out from the solid-state image pickup device 1 is once stored in the memory 10, and the image in the memory 10 is 1 / k by an image processing circuit 11 by a computer.
It is a method of doubling.

According to this method, the image processing circuit can not only enlarge the image 1 / k times, but also correct the distortion aberration of the lens system (including the distortion aberration of the non-rotationally symmetric image). Therefore, a more correct image can be obtained as compared with the configuration shown in FIG. Further, a freely transformed image can be obtained. Here, the R.D. G. The B format signal is displayed on the TV monitor. Next, the configuration of the lens system 2 will be described.

As described above, the lens system 2 has different magnifications in the horizontal direction and the vertical direction, and satisfies the relationship of the following expression (4). β _z / β _y ≈k (4) where β _z is the horizontal magnification and β _y is the vertical magnification.

For example, in the analmorphic optical system of FIG.
(A) is a cross-sectional view as seen from the horizontal scanning direction, and (B) is a cross-sectional view as seen from the vertical direction. In a retrofocus type lens system, one or more non-rotationally symmetrical front and rear iris planes, respectively. This is a configuration in which an aspherical surface (A _S ) is provided. This aspherical surface (A
_S) in the FIG. 3 (A), the radius of curvature small, (B)
Has a large radius of curvature.

This aspherical lens is shaped like a rugby ball as shown in FIG. 4, and is expressed by the following equation (5).

In this equation, i represents the surface number. The reason that there is no odd-order term of y and z in this equation is that the aspherical surface is symmetrical with respect to the horizontal section and the vertical section. R _i is the radius of the spherical surface, and the first term represents the component of the axisymmetric spherical surface. The origin of FIG. 4 is the apex of the aspherical surface. Also, the curvature R in the y and z directions of the paraboloid of the parabola at the crest
_y and R _z are given by the following equations (6) and (7), respectively. 1 / R _y = 2B _y (6) 1 / R _z = 2B _z (7) It is necessary to provide at least one aspherical surface given by the above formula (5) in the lens system, and as shown in FIG. If two or more surfaces are provided with a diaphragm in between, it is advantageous for correction of astigmatism, curvature of field and correction of astigmatism Δ on the optical axis.

The astigmatism Δ on the optical axis is the difference between the paraxial image point in the horizontal direction and the paraxial image point in the vertical direction. If this value is not sufficiently small, the image will be blurred over the entire screen.

The conditions under which this Δ is small and the image can be reduced in the horizontal direction are as follows.

Assuming that an anamorphic surface (toric surface) as shown in FIG. 4 exists on the i-plane before the diaphragm and the j-plane after the diaphragm, the refractive index of the medium before and after the i-plane is n _{i-1 respectively.} And n
The refractive index of the medium before and after the _i- or j-plane is n _j-1 and n _{j, respectively.}
Then, the power in the horizontal direction (z direction) and the vertical direction (y direction) of the i-plane and the j-plane are defined by the following equation. φ _yi = 2 (n _i −n _{i −1} ) B _yi (10) φ _zi = 2 (n _i −n _{i −1} ) B _zi (11) φ _{y j} = 2 (n _j −n _{j −1} ) B _yj (12) φ _zj = 2 (n _j −n _j-1 ) B _zj (13) In the above equation, φ _yi is the vertical i-plane power, φ _zi is the horizontal i-plane power, and φ _yj is Vertical j-plane power, φ
_zj is the power of the j surface in the horizontal direction.

In order to reduce the image in the horizontal direction, it is sufficient to satisfy the formula (14) before the diaphragm and the formula (15) after the diaphragm. φ _yi > φ _zi (14) φ _yj <φ _zj (15) As the i- and j-planes, which are surfaces having a principal ray height higher than the marginal ray height, are located near the object-side lens or the image-side lens. It should be provided.

On the other hand, in order to reduce the value of Δ to 0, it is necessary to consider the converging action on paraxial rays and satisfy the following expression (16). (Φ _zi −φ _yi ) (φ _zj −φ _yj ) <0 (16) The above equation (16) is satisfied if the equations (14) and (15) are satisfied.

Therefore, before and after the diaphragm,
If an anamorphic surface satisfying (15) is provided, Δ
It is possible to obtain an optical system that reduces the image in the horizontal direction and has a small value of.

When three or more anamorphic surfaces are provided by providing at least one surface each before and after the diaphragm, one of the surfaces is expressed by the formula (14) in order to perform the reduction in the horizontal direction (z direction). Alternatively, it is necessary to satisfy the formula (15).

In order for Δ = 0, it is necessary to satisfy the equation (17) for at least one set of surfaces m and n. (Φ _zm −φ _ym ) (φ _zn −φ _yn ) <0 (17) where φ _zm is the power of the m plane in the z direction, φ _ym is the power of the m plane in the y direction, and φ _zn is the z power of the n plane. The power in the direction, φ _yn, is the power in the y direction of the n-plane.

Alternatively, instead of equations (14) and (15), it is necessary to satisfy the following equations (18) and (19), respectively. Further, since Δ = 0, the following expression (20) may be satisfied instead of satisfying the expression (17). However, h _zn and h _yn are paraxial ray heights on the n plane in the z direction and the y direction, respectively. This equation (20) is expressed in the z direction and the y direction.
This means that the sum of the refraction angles for paraxial rays in the direction becomes approximately 0, which is a necessary condition for Δ = 0. However, practically, it is sufficient to satisfy the following expression (22) instead of the expression (21).

[0032] Here, φ _z = 1 / f _Z , φ _y = 1 / f _y , f _z and f _y are focal lengths in the z direction and y direction, _respectively , and h _z0 and h _y0 are the first in the z direction and the y direction, respectively. It is the paraxial incident ray height of the surface.

In this optical system, when the anamorphic surface is provided only before the diaphragm or only after the diaphragm, the reduction of the image in the horizontal direction and Δ = 0 are not compatible with one surface, but the anamorphic surface is not compatible. If the height of the marginal ray of is smaller than the height of the chief ray on the anamorphic surface, then Δ≈0
As a result, there is a satisfactory effect. For that purpose, the anamorphic surface may be placed on the surface away from the stop, that is, in the vicinity of the most object side surface of the lens system or in the vicinity of the most image side surface. Then, either the expression (14) should be satisfied for the front surface of the diaphragm, or the expression (15) should be satisfied for the rear surface of the diaphragm.

When two or more anamorphic surfaces are provided only before the diaphragm or only after the diaphragm, it is possible to satisfy both the reduction in the horizontal direction and Δ = 0 by satisfying the following conditions. .. That is, the reduction condition in the horizontal direction is that at least one surface satisfies the condition (14) before the diaphragm,
After squeezing, the expression (15) should be satisfied.

In order to realize Δ = 0, it is necessary to satisfy the equation (22) for at least one set of surfaces k and l.

As for the shape of the anamorphic surface, it is preferable that at least one of the horizontal sectional shape and the vertical sectional shape is not circular. This is because the aspherical shape can be freely selected and the aberration can be corrected well. (Φ _zk −φ _yk ) (φ _zl −φ _zl ) <0 (22) The allowable value of Δ in the above-described example is as shown in the following (23).

However, F _Noy and F _Noz are the F numbers in the y and z directions, respectively, and P _V and P _H are the vertical and horizontal lengths of one pixel of the CCD.

The position of the CCD 1 on the optical axis is near the center between the paraxial image forming point in the horizontal direction and the paraxial image forming point in the vertical direction,
Alternatively, it is preferable to set it slightly closer to the lens in consideration of the field curvature.

[0039]

EXAMPLES Next, examples of the present invention will be shown. Example 1 _{(z-direction) f z = 1.000, F N0z} = 4.218, NA = -0.0105, ω = 43.874 ° IH = 0.7280, β z = -0.08859, φ z = 1.0 object distance = -10.8696 r ₁ = ∞ d ₁ = 0.3304 n ₁ = 1.88300 ν ₁ ＝ 40.78 r ₂ ＝ 0.6783 d ₂ ＝ 0.6000 r ₃ ＝ 3.5348 d ₃ ＝ 1.3652 n ₂ ＝ 1.72916 ν ₂ ＝ 54.68 r ₄ ＝ -1.3600 d ₄ ＝ 0.0870 r ₅ ＝ ∞ ) D ₅ = 0.3478 n ₃ = 1.52287 ν ₃ = 59.89 r ₆ = ∞ d ₆ = 0.0261 r ₇ = ∞ d ₇ = 0.5391 n ₄ = 1.52000 ν ₄ = 74.00 r ₈ = ∞ d ₈ = 0.1391 r ₉ = 2.9104 d _{9 = 1.2609 n 5 = 1.69680 ν} 5 = 55.52 r 10 = -0.9191 d 10 = 0.2609 n 6 = 1.84666 ν 6 = 23.78 r 11 = -3.8252 d 11 = 0.0870 r 12 = ∞ d 12 = 0.3478 n 7 = 1.52287 ν ₇ = 59.89 r ₁₃ = ∞ d ₁₃ = 0.5739 r ₁₄ = ∞ d ₁₄ = 0.8696 n ₈ = 1.51633 ν ₈ = 64.15 r ₁₅ = ∞ paraxial ray height k Y 1 0.114130 2 0.115973 3 0.212861 4 0.305687 5 0.301659 6 0.291079 7 0.28987 0 8 0.273440 9 0.266996 10 0.185074 11 0.173763 12 0.163457 13 0.136384 14 0.068359 15 0.000386 (y direction) f _y = 1.404, F _Noy = 6.100, NA = -0.0105, ω = 27.596 ° IH = 0.7280, β _y = -0.12852, φ _y = 0.7122, Δ = 0.003 Object distance = -10.8696 r ₁ = ∞ (aspherical surface) d ₁ = 0.3304 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.6783 d ₂ = 0.6000 r ₃ = 3.5348 d ₃ = 1.3652 n ₂ = 1.72916 ν ₂ = 54.68 r ₄ = -1.3600 d ₄ = 0.0870 r ₅ = ∞ (aperture) d ₅ = 0.3478 n ₃ = 1.52287 ν ₃ = 59.89 r ₆ = ∞ d ₆ = 0.0261 r ₇ = ∞ d ₇ = 0.5391 n ₄ = 1.52000 ν ₄ = 74.00 r ₈ = ∞ d ₈ = 0.1391 r ₉ = 2.9104 d ₉ = 1.2609 n ₅ = 1.69680 ν ₅ = 55.52 r ₁₀ = -0.9191 d ₁₀ = 0.2609 n ₆ = 1.84666 ν ₆ = 23.78 _{r 11 = -3.8252 d 11 = 0.0870} r 12 = ∞ d 12 = 0.3478 n 7 = 1.52287 ν 7 = 59.89 r 13 = ∞ ( _{aspherical) d 13 = 0.5739 r 14 =} ∞ d 14 = 0.8696 _{8 = 1.51633 ν 8 = 64.15 r} 15 = ∞ aspherical coefficients (first surface) B = 0.14670, (thirteenth surface) B = .25000 paraxial ray height k Y 1 0.114503 2 0.111146 3 0.186486 4 0.255252 5 0.250925 6 0.239561 7 0.238263 8 0.220616 9 0.213693 10 0.138704 11 0.127643 12 0.118377 13 0.094040 14 0.046998 15 -0.000008 E _i = 0, F _i = 0, G _i = 0, φ _y1 = 0.25907, φ _y14 = -0.2614 φ _z1 = 0, φ _z14 = 0 (φ _zi −φ _yi ) · (φ _zj −φ _yj ) = (− φ ₁ ) · (−φ ₁₄ ) = − 0.06772 <0 Σ (φ _zn h _zn −φ _yn h _yn ) = 0.00508, 1 / 3 (φ _z h _zo + φ _{y hyo} ) = 0.0653 φ _y1 h _y1 = 0.02966, φ _z1 h _z1 = 0, φ _y14 h _y14 = -0.02458, φ _z14 h _z14 = 0, h _yo = h _zo = 0.114503, φ _y h _yo = 0.08155, φ _z h _zo = 0.1145 Example 2 (z direction) f _z = 1.000, F _N0z = 5.906, NA = -0.0075, ω = 57.282 ° IH = 0.8948, β _z = -0.08859 Object distance = -10.8696 r ₁ = ∞ d ₁ = 0.3304 n ₁ = 1.88 300 v ₁ = 40.78 r ₂ = 0.6783 d ₂ = 0.6000 r ₃ = 3.5348 d ₃ = 1.3652 n ₂ = 1.72916 v ₂ = 54.68 r ₄ = -1.3600 d ₄ = 0.0870 r ₅ = ∞ (aperture) d ₅ = 0.3478 n ₃ = 1.52287 ν ₃ = 59.89 r ₆ = ∞ d ₆ = 0.0261 r ₇ = ∞ d ₇ = 0.5391 n ₄ = 1.52000 ν ₄ = 74.00 r ₈ = ∞ d ₈ = 0.1391 r ₉ = 2.9104 d ₉ = 1.2609 n ₅ = 1.69680 v ₅ = 55.52 r ₁₀ = -0.9191 d ₁₀ = 0.2609 n ₆ = 1.84666 v ₆ = 23.78 r ₁₁ = -3.8252 d ₁₁ = 0.0870 r ₁₂ = ∞ d ₁₂ = 0.3478 n ₇ = 1.52287 v ₇ = 59.89 r ₁₃ = ∞ d ₁₃ = 0.5739 r ₁₄ = ∞ d ₁₄ = 0.8696 n ₈ = 1.51633 ν ₈ = 64.15 r ₁₅ = ∞ Paraxial ray height k Y 1 0.081522 2 0.082838 3 0.152044 4 0.218348 5 0.215471 6 0.207913 7 0.207050 8 0.195315 9 0.190711 0.132196 11 0.124117 12 0.116755 13 0.097417 14 0.048828 15 0.000276 (y direction) _fy = 1.000, F _N0y = 5.924, NA = -0.0075, ω = 41.248 ° IH = 0.8948, β _y = -0.08859, Δ = 0, object distance = -10.8696 r ₁ = ∞ (aspherical surface) d ₁ = 0.3304 n ₁ = 1.88300 ν ₁ = 40.78 r ₂ = 0.6783 d ₂ = 0.6000 r ₃ = 3.5348 _{d 3 = 1.3652 n 2 = 1.72916} ν 2 = 54.68 r 4 = -1.3600 d 4 = 0.0870 r 5 = ∞ ( _{stop) d 5 = 0.3478 n 3 =} 1.52287 ν 3 = 59.89 r 6 = ∞ d 6 = 0.0261 r 7 ＝ ∞ d ₇ ＝ 0.5391 n ₄ ＝ 1.52000 ν ₄ ＝ 74.00 r ₈ ＝ ∞ d ₈ ＝ 0.1391 r ₉ ＝ 2.9104 d ₉ ＝ 1.2609 n ₅ ＝ 1.69680 ν ₅ ＝ 55.52 r ₁₀ ＝ -0.9191 d ₁₀ ＝ 0.2609 n ₆ ＝ 1.84666 ν ₆ = 23.78 r ₁₁ = -3.8252 (aspherical surface) d ₁₁ = 0.0870 r ₁₂ = ∞ d ₁₂ = 0.3478 n ₇ = 1.52287 ν ₇ = 59.89 r ₁₃ = ∞ d ₁₃ = 0.5739 r ₁₄ = ∞ d ₁₄ = 0.8696 n ₈ = 1.51633 ν ₈ = 64.15 r ₁₅ = ∞ Aspheric surface coefficient (1st surface) E = 0.13000, (11th surface) E = 0.18000 Paraxial ray height k Y 1 0.081275 2 0.082587 3 0.151583 4 0.217686 5 0.214818 6 0.207284 7 0.2064 23 8 0.194723 9 0.190134 10 0.131796 11 0.123741 12 0.116401 13 0.097122 14 0.048680 15 0.000275 B _y1 = B _z1 = F _j1 = G _j1・ ・ ・ ・ ・ = 0, E ₁₁ = 0.13, E ₂₁ = 0.065, E ₃₁ =
0, E ₁₁₄ = 0.18, E ₂₁₄ = 0.09, E ₃₁₄ = 0, By ₁₄ = B _z14 = F _j14 = G
_j14 ... ・ = 0 (j = 1,2,3, ...) where r ₁ , r ₂ , ... _{Are the} radii of curvature of each surface of the lens, d
₁ , d ₂ , ... Is the thickness of each lens and the lens interval, n
₁ , n ₂ , ... Are the refractive indices of the respective lenses, ν ₁ , ν ₂ ,.
Is the Abbe number of each lens.

Example 1 has the structure shown in FIGS. 5 and 6, of which FIG. 5 is a sectional view in the z direction and FIG. 6 is a sectional view in the y direction. In the first embodiment, cylindrical objects are used before and after the diaphragm so that a rectangular object range can be imaged on a square CCD.

However, β _H is the same as β _z, and β _H
v is the same as β _y .

The optical system according to this embodiment has β _z = -0.08859,
β _y = -0.12852 and β _z / β _y = 0.6893≈9 / 16≈0.5625.

It seems that there is a difference between the values of β _z / β _y and 9/16, but the horizontal half angle of view ω _H = −43 ° 87 and the vertical half angle of view ω _V = −27. The angle ratio is 596, and the aspect ratio of the imaged object surface is as follows. tan27 ° 596 / tan43 ° 87 = 0.5437 ≒ 9/16 Therefore, considering the dimensions of the object plane, it matches the aspect ratio of high-definition television.

The above distortion is caused by distortion.

Therefore, practically, the value of β _z / β _y is
It may be quite far from 9/16. Since data such as characters may be displayed together with the image, β _z / β _y may be within the following range even in consideration of this point. 0.25 <β _z / β _y <0.97 (24) FIGS. 7 and 8 are views showing the configuration of the second embodiment of the present invention, FIG. 7 is a y-direction and FIG. 8 is a z-direction sectional view.

In the second embodiment, the paraxial magnifications in the vertical and horizontal directions are equal, but the amount of distortion aberration in the z direction is changed to contract the laterally long object range in the lateral direction for imaging.

In this embodiment, one aspherical surface having a rotationally asymmetric component in the fourth-order term is provided before and after the diaphragm.

When the surface number of the aspherical surface before the stop is p and the surface number of the aspherical surface after the stop is q, E _1p (n _p −n _p-1 ) = φ _yp (25) E _3p ( If n _p −n _p−1 ) = φ _zp (26), then (p is replaced by q, equation (25) and equation (2
(6) can be similarly defined for the q-plane), and it is desirable to satisfy the following equations (27) and (28) in order to reduce the field curvature in each of the y and z directions. ψ _yp · ψ _yq <0 (27) ψ _zp · ψ _zq <0 (28) It means that the fourth-order term E _ap (a = 1 or 3) is the next to the third-order astigmatism A _p of the P-plane. This is because it contributes. A _p = 8h _ap ² · h _bp ² · ψ _yp (29) Similarly, for the q-plane, the third-order astigmatism coefficient A _q is as follows. A _q = 8h _aq ² · h _bq · ψ _yp (30) h _ap and h _bp in the above equation (29) are the paraxial marginal ray height and paraxial chief ray height on the p-plane, respectively. Similarly, equation (30)
_Where h _aq and h _bq are paraxial marginal ray heights in the q-plane,
It is the paraxial chief ray height.

From the above equation, in order to make A _p + A _{q ≈0} , ψ _yp and ψ _yq must have _opposite signs.

Similarly, ψ _zp and ψ _zq in the z direction must also have different signs.

In the second embodiment, β _y = β _z and f _y = f _z
And Δ = 0, but the horizontal half angle of view ω _H = 57
The angle is 282 and the vertical half angle of view ω _V = 41 ° 248.

Therefore, it becomes as follows. (Tan ω _H / tan ω _V ) ⁻¹ = 0.5634≈9 / 16 That is, the second embodiment is an example in which the angle of view in the horizontal and vertical directions is controlled by controlling the distortion aberration.

As described above, the second embodiment is characterized in that the resolution of the important visual field center is good because Δ = 0.

In the above description, the case where the present invention is applied to an image pickup apparatus which is generally used for observing on a TV monitor using a solid-state image pickup element is described. The above-described present invention can be applied as it is to an electronic endoscope or the like that is observed on a television monitor or the like using the.

FIG. 13 is a diagram showing an illumination optical system used in the electronic endoscope of the present invention. Since the object imaged in the present invention is horizontally long, the illumination optical system must also illuminate the horizontally long range. FIG. 13 shows an example thereof, in which concave lenses 22 and 23 are arranged in front of the light guide 21, and these concave lenses are decentered in the z direction with respect to the light guide. This spreads the illumination light in the z direction. At this time, the concave lens 22 may be decentered inward with respect to the light guide in the z direction as shown in FIG.

FIG. 14 shows an example of another illumination optical system used in the present invention, in which an anamorphic concave lens 24 is arranged in front of a light guide having a round end surface. FIG. 15 is a cross-sectional view of FIG. 14, where (A) is a horizontal direction and (B) is a vertical direction.
As shown in the figure, the power of the concave lens is weaker in the vertical section than in the horizontal section. This surface shape is similarly expressed by the equation (5). Even if a round light guide is used as shown in this figure, a light distribution spread in the horizontal direction can be obtained.

The present invention is not limited to electronic endoscopes and can be applied to image pickup devices such as television cameras and electronic cameras. Further, the shape correction by the electronic circuit does not have to be performed, or may be variable as necessary. The present invention can be applied to not only high-definition television but also television systems such as NTSC and PAL because the display screen shape is not square.

The present invention can be applied even when the shape of the solid-state image pickup device is similar to that of the display section of the television monitor, or when the shape of the display image is desired to be changed because character data and the like are also displayed.

Further, not only the aspect ratio but also the ratio in the diagonal direction may be changed to pick up an image, which may be transformed by an electronic circuit and displayed on a television monitor. In that case, the magnifications in the two directions orthogonal to each other correspond to β _H and β _v in the present invention described above. The above two directions correspond to the y direction and the z direction.

The CCD used in the present invention is a horizontal CCD.
It is desirable to use a pixel whose length is smaller than the length of one pixel in the vertical direction. The reason is that it is preferable that the pixel pitch in the horizontal direction is dense because the image is displayed in a widened manner in the horizontal direction. This is the current NTSC CC
It is promising because D is expected to do so in the future. In this case, the aspect ratio is 4/3, so A =
If it is set to 4/3, the formula of the present invention can be applied as it is, and the formulas (29) and (30) below can be used. β _z / β _y ≈1 / A = 0.75 (31) (tan ω _H / tan ω _v ) ⁻¹ ≈1 / A = 0.75 (32)

[0061]

According to the present invention, a compact and powerful image can be displayed without wasting the television monitor display section.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an image pickup apparatus of the present invention.

FIG. 2 is a diagram showing the configuration of another example of the present invention.

FIG. 3 is an example showing a configuration of an optical system used in the image pickup apparatus of the present invention.

FIG. 4 is a schematic view of an aspherical shape used in the optical system.

FIG. 5 is a horizontal sectional view of Example 1 of the optical system used in the present invention.

FIG. 6 is a vertical sectional view of the first embodiment.

FIG. 7 is a sectional view of a second embodiment of the optical system used in the present invention.

FIG. 8 is a vertical sectional view of the second embodiment.

9 is a horizontal aberration curve diagram of the first embodiment. FIG.

FIG. 10 is a vertical aberration curve diagram of the first embodiment.

FIG. 11 is a horizontal aberration curve diagram of Example 2 above.

FIG. 12 is a vertical aberration curve diagram of the second embodiment.

FIG. 13 is a diagram showing a configuration of an illumination optical system used in an electronic endoscope to which an image pickup apparatus of the present invention is applied.

FIG. 14 is a diagram showing another example of the illumination optical system used in the electronic endoscope.

FIG. 15 is a horizontal and vertical sectional view of the illumination optical system shown in FIG.

FIG. 16 is a diagram showing an outline of a configuration of a conventional imaging device.

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Claims (2)

[Claims] 1. An objective lens for forming an image of an object, a collective image pickup device for receiving an image by the objective lens, a signal processing unit for generating an output signal from the image pickup device, and an object for the image signal. A display means for displaying an image,
The objective lens has a rotationally asymmetric refracting surface represented by the following formula (5) and projects a deformed image of the object onto the solid-state imaging device, and the signal processing unit further deforms the deformed image. Image display device that displays the image. However, x, y, and z are coordinate values of xyz coordinates when the optical axis direction is the x axis and the vertex of the surface is the origin. 2. An illuminating means for illuminating an object, an objective lens for forming an image of the object, a solid-state image sensor for receiving an image by the objective lens, and a video signal generated from an output signal from the solid-state image sensor. Signal processing means and a display means for displaying an image of the object by the video signal, the objective lens has a rotationally asymmetric refracting surface to project a deformed image of the object on the solid-state imaging device, An electronic endoscope in which the signal processing unit further deforms and displays the deformed image.