JP2003235794A - Electronic endoscopic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible not only to magnify the depth of field but also to form an image of high resolving power even if an endoscope having an optical phase modulation mask is connected to a signal processor loaded with no restoration processing means corresponding to the optical phase modulation mask arranged to an endoscopic optical system and to further magnify the depth of field while forming an image of higher resolving power when the endoscope having the optical phase modulation mask is connected to the signal processor loaded with the restoration processing means corresponding to the optical phase modulation mask. <P>SOLUTION: The image processing circuit 27 of a depth-of-field external processing circuit 12 is a circuit for applying filtering processing to an image signal and performs the response of an optical transmission function and image processing for restoring asymmetric aberration (blur) generated by a pupil modulation element. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope system.
In particular, for multiple systems, multiple types of endoscopes with different specifications and
To connect and view images of the subject on a monitor
Related to an endoscope system. [0002] As is well known, an endoscope cannot be directly viewed.
Can observe the inside of a living body, etc.
Widely used for treatment and treatment. And recently, the subject
Images are converted to electrical signals by a solid-state image sensor such as a CCD
Electronic endoscopes that can be observed on a monitor
You. [0003] Such an endoscope depends on a site to be observed.
Various endoscopes are used. The endoscope is a light source
Camera controller including signal processing circuit (signal processing device)
It is used by being connected to etc. In the signal processing circuit,
An image processing circuit is provided to improve image quality and emphasize the subject.
For improving the contrast, for example,
A symmetric two-dimensional digital filter is used as shown in
Have been. The following matrix shows the center pixel and its
Is determined for the values of the pixels around the pixel. [0004] On the other hand, the endoscope optical system has a simple optical system and excellent operability.
Therefore, fixed focus optics are commonly used
Designed to obtain the required depth of field depending on the part
Have been. However, with a fixed focus optical system,
Then, it is necessary to increase the F number of the optical system.
There is a problem that the reliability is reduced. In addition, the times of light
There is a limit to the extension of the depth of field because of the folding limit. This
On the other hand, the method of expanding the depth of field of an optical system
For example, U.S. Pat. No. 5,748,371 or "Edward
R. Dowski, Jr. , W.S. Thomas C
athey, "Extended depth of
fieldthrough wave-front
coding, "Appl. Opt. Vol. 34,
1859-1866 (1995) ".
You. FIG. 17 shows a configuration of a conventional enlarged depth of field optical system.
FIG. An apparatus according to this technique is shown in FIG.
As described above, the imaging means 104 such as a CCD and the image of the object 101
Lens system 103 that forms an image on the light receiving surface of the imaging unit 104
Phase change at the pupil position of the optical system
Image data from the tone mask 102 and the imaging means 104
Image processing apparatus 105 that constructs an image based on the
I have. [0006] The cubic phase modulation mask 102
One side is a plane, and the other side is Z as shown in FIG.
= A (X ^Three + Y ^Three ). FIG.
Explains the external shape of this cubic phase modulation mask
FIG. A is an arbitrary coefficient. Sandals
That is, one surface is a plane on the XY plane, and the other surface is
Satisfies the above equation in the Z-axis direction orthogonal to the XY plane.
It is a dimensional surface. FIG. 18 shows that X and Y are −1 to +1.
FIG. 7 is a diagram for explaining a state of a three-dimensional curved surface in a range.
You. Accordingly, the three-dimensional curved surface shape changes according to the coefficient A.
You. [0007] The cubic phase modulation mask 102 is
P (X, Y) = exp (jα)
(X ^Three + Y ^Three )). Here, the coefficient α is 2
A value sufficiently larger than 0 is preferable, and
The response of the transfer function (hereinafter also referred to as OTF) is
0.2 or less, due to rotationally asymmetric aberration (blur)
The size of the image is sufficiently larger than the pixels of the imaging unit 104.
It becomes. [0008] Such a cubic phase modulation mask 1
In the case of a normal optical system without 02, the object 101 is in focus.
The response of the optical transfer function
The state changes from FIG. 19 to FIG. 20, and the object 101 is further
, The state changes from FIG. 20 to FIG. FIG. 19 shows that an object is focused in a normal optical system.
Response of optical transfer function (OTF) when in position
4 is a graph showing the results. FIG. 20 shows an ordinary optical system.
The optical transfer function (OT
It is a graph which shows the response of F). FIG. 21 shows a normal
In the optical system, the object is moved from the focal position
Response of optical transfer function (OTF) when deviated further
4 is a graph showing the results. On the other hand, a cubic phase modulation mask
In the case of an extended depth-of-field optical system with 102,
The response of the OTF is shown in FIGS.
As shown in the figure, the OTF
Ponce is seen to decrease, but
Change is small. FIG. 22 shows an object in an enlarged depth of field optical system.
Of the optical transfer function (OTF) when the body is in focus
It is a graph which shows a response. FIG. 23 shows an enlarged depth of field.
Optics when an object deviates from the focal position
4 is a graph showing an intensity distribution of an objective transfer function (OTF).
FIG. 24 shows the focus position of the object in the enlarged depth of field optical system.
The optical transmission function when it deviates from that of FIG.
It is a graph which shows the response of number (OTF). The image formed by this optical system is
The cubic image shown in FIG.
To the inverse filter of the OTF characteristic of the
The processing shown in FIGS.
26 to 28 respectively for the OTFs
OTF response is obtained. FIG. 25 shows light in an enlarged depth-of-field optical system.
Is performed on the response of the biological transfer function (OTF)
13 is a graph showing characteristics of an inverse filter of the processing performed by the first embodiment. FIG.
Corresponds to the response of the optical transfer function (OTF) in FIG.
25 and perform processing by an inverse filter having the characteristics of FIG.
The response of the optical transfer function (OTF) obtained by
This is a graph. FIG. 27 shows the optical transfer function (O
TF) response to the reverse filter having the characteristics shown in FIG.
Optical transfer function (O
It is a graph which shows the response of TF). FIG. 28 shows FIG.
4 for the response of the optical transfer function (OTF)
Obtained by performing processing with an inverse filter having 25 characteristics.
Graph showing the response of the optical transfer function (OTF)
It is. The OTF response shown in FIGS.
In all cases, the OTF ratio at the time of normal optical system focusing is
It has a shape similar to a sponge. And its inverse filter
For example, an asymmetric two-dimensional digital
Ruta is used. The matrix below shows the center pixel
And the coefficients for the values of the surrounding pixels.
You. [0015] Next, an actual image will be described. In ordinary optical systems, objects
As the focus shifts from
Come up. On the other hand, an enlarged depth of field optical system is used.
The image before image processing when the focal position is shifted
Each image is blurred, but the focus position is shifted
Does not change the way of blurring. And these images
On the other hand, the image processing by the above-described inverse filter (FIG. 25) is performed.
Is equivalent to an image without a normal optical system defocus
And the depth of field can be increased. Further, an application of this to an endoscope is as follows.
It is disclosed in the specification of JP-A-2000-5127.
You. The disclosed endoscope system is shown in FIG.
Is connected to a plurality of types of endoscopes to monitor the image of the subject
16 is an endoscope system for observation at 16. The endoscope system shown in FIG.
The solid-state image sensor 114 and the solid-state image sensor 114
An objective optical system 112 for forming an image of a subject on a light receiving surface;
Endoscope 111 and an image signal obtained by the endoscope 111
Camera controller that processes video signals and outputs video signals
(Signal processing device) 117 and generates illumination light for observation
The light source device 118 and the image from the camera controller 117
And a monitor 116 for displaying an image signal. At least one of a plurality of types of endoscopes
The endoscope 111 has a cubic phase change in the optical system 112.
It has an optical phase modulation mask 113 such as a tone mask.
Further, the endoscope 111 is provided on the output side of the imaging device 114.
Optical transmission function corresponding to the optical phase modulation mask 113 of the endoscope
Number restoring means 115 is provided. Further, the camera controller 117 is provided in FIG.
0, an image signal from the connected endoscope 111 is displayed.
A / D converter 121 for converting the signal into a digital signal;
A signal converter 122 for converting the digital signal into a video signal
And an image for processing the video signal from the signal conversion unit 122.
An image processing circuit 123;
Analog signal that can display the processed video signal on the monitor 4
And a D / A conversion unit 124 that converts the data into a digital signal. The optical transfer function restoring means 115 includes an optical system
Equivalent to inverse filter of optical phase modulation mask 113 in 112
It is necessary to include the restoration means to be performed. Optical transfer function
The restoration means 115 is provided for the endoscope 11 as shown in FIG.
1 may be provided inside, or the endoscope 111 may be connected thereto.
Camera controller for displaying video on monitor 116
(Signal processing device) 117 may be provided. to this
According to the type and presence or absence of the optical phase modulation mask 113,
Instead, even if various endoscopes are connected, the depth of field will increase,
High-resolution images can be generated. [0022] US Patent 5,748,
No. 371, JP-A-2000-5127, etc.
First, the optical field modulation mask 113 is used for the optical character system,
When applying the technology to increase the depth to the endoscope, the optical phase change
Restores the deterioration of the optical transfer function due to the tone mask 113,
Optical transfer function restoring means 11 for obtaining high resolution image
5 is required, so that one-to-one
Restoration means corresponding to the camera controller (signal processing device).
Placement) Image processing circuit in 117 or in endoscope 111
It must be installed in the department. However, the current general endoscope system
The image processing circuit in the camera controller in the system
Optical transmission of images obtained through imaging optics
Emphasize specific frequency bands for function response
Image processing circuit that adjusts the appearance of the image
But for the purpose of expanding the depth of field
Also, depending on the optical phase modulation mask installed in the endoscope optical system
The endoscope optical system,
When an endoscope with an optical phase modulation mask is connected,
Image cannot be obtained, and compatibility cannot be ensured. In order to ensure compatibility, the inside of the endoscope is
When an optical transfer function restoring means is provided in the
A / D converter for converting to a digital signal, and a digital signal
A signal conversion unit for converting the converted image signal into a video signal,
An image processor for restoring the optical transfer function
Signal conversion unit for converting a signal from an image signal to an image signal;
A conversion unit is required inside the endoscope, but the circuit is complicated
And the circuit scale is large, so the endoscope body is enlarged.
And the disadvantage that operability is deteriorated occurs. The present invention has been made in view of the above circumstances.
And is compatible with the optical phase modulation mask placed in the endoscope optical system.
Signal processing device that does not have the same restoration processing means,
Even if an endoscope with an optical phase modulation mask is connected,
Can increase the depth and generate high-resolution images, and
Restoration processing means corresponding to the optical phase modulation mask is installed.
Endoscope having the optical phase modulation mask in a signal processing device
When a mirror is connected, the depth of field further increases, and
Providing an endoscope system that can generate even higher resolution images
It is intended to be. An electronic endoscope system according to the present invention is provided.
The system captures the optical image of the objective optical system with a solid-state image sensor.
Signals from the plurality of types of endoscopes and the solid-state imaging device.
Multiple signal processing devices that convert video signals
An electronic endoscope system used in combination with
At least one objective optical system of said endoscope
Has an optical phase modulation mask, the optical phase modulation mask
Changes in the optical transfer function according to the object distance
Smaller than objective optics without phase modulation mask
The signal processing device is arranged to operate as
Optical transfer function modified by the optical phase modulation mask
On the other hand, multiple optical transfer function restoration processing according to object distance
Is provided. The present invention will be described below with reference to the drawings.
An embodiment will be described. First Embodiment: FIGS. 1 to 15 show a book
FIG. 1 shows an endoscope system according to a first embodiment of the invention.
FIG. 2 is a configuration diagram showing a schematic configuration of a system, and FIG.
Diagram for explaining the configuration of an imaging unit including a mask,
FIG. 3 shows a structure of a pupil modulation element in which the aperture stop of FIG. 2 is arranged.
FIG. 4 is a schematic explanatory view for explaining the camera control, and FIG.
FIG. 5 is a block diagram showing the configuration of a roller (signal processing device).
Is the object distance 71 of the imaging unit including the pupil modulation element of FIG.
The simulation result of the point image obtained when
FIG. 6 is a view for explaining an image pickup unit including the pupil modulation element of FIG.
Of the point image obtained when the object distance of the knit is 13.5 mm
FIG. 7 is a diagram for explaining a simulation result, and FIG.
Object distance of the imaging unit including the pupil modulation element of 7.2 mm
The point image simulation results obtained at
FIG. 8 shows an imaging unit including the pupil modulation element shown in FIG.
Simulation of a point image obtained when the object distance is 4 mm
FIG. 9 is a diagram for explaining the result of the pupil modulation shown in FIG.
Obtained when the object distance of the imaging unit including the child is 3 mm
For explaining the simulation result of a point image
Reference numeral 10 denotes each object distance of the imaging unit including the pupil modulation element of FIG.
Simulation results of the response of the separated optical transfer function
FIG. 11 is a view for explaining the result, and FIG.
It is obtained when the object distance of the imaging unit of FIG. 2 is 71 mm.
For explaining the simulation result of a point image
12 is an object of the imaging unit of FIG. 2 in a normal optical system
Simulation of a point image obtained at a distance of 13.5 mm
FIG. 13 is a diagram for explaining the result of the installation, and FIG.
When the object distance of the imaging unit in Fig. 2 is 7.2mm
To explain the simulation results of the point image obtained
14 and FIG. 14 show the imaging unit of FIG. 2 in a normal optical system.
Simulation of a point image obtained when the object distance is 4 mm
FIG. 15 is a diagram for explaining the result of the operation, and FIG.
For each object distance of the imaging unit in FIG.
Of the response of the biological transfer function
It is a figure for clarification. (Structure) As shown in FIG.
5 and a pair for forming an image of a subject on the solid-state imaging device 5.
An endoscope 1 having an object optical system 6 and an endoscope 1 obtained by the endoscope 1
Camera control that processes image signals and outputs video signals
(Illumination light for observation)
A video signal from the light source device 3 and the camera controller 2
And a monitor 4 for displaying. And the form of this implementation
Endoscope system is connected to multiple types of endoscopes 1
Can be used for multiple types of endoscopes
At least one endoscope 1 of the mirrors 1 has its objective light
In the optical system 6, an optical element having a rotationally asymmetric surface shape
An optical phase modulation mask 7 is provided. As shown in FIG. 2, the imaging unit of the endoscope 1
20 is a solid-state image sensor 5 and a subject image
Is constituted by an objective optical system 6 which forms an image. FIG. 3A is viewed from the direction in which light is incident.
FIG. 7 is a diagram showing the appearance of the pupil modulation element 7a and the aperture stop 8 at the time.
is there. The aperture stop 8 is parallel to the XY plane perpendicular to the incident light.
Light incident through the aperture of the aperture stop 8
The light enters the pupil modulation element 7a. Also, as shown in FIG.
As seen from the light incident direction, the back of the aperture stop 8
At the position, a pupil modulation element 7a is used as the optical phase modulation mask 7.
Are located. Solid-state image sensor used in the present embodiment
The element 5 has a pixel pitch of 7 μm, for example.
You. Further, a pupil modulation element used as the optical phase modulation mask 7
7a is an optically transparent glass having a refractive index of 1.523, for example.
Optically over a wide depth of field
This is a conversion means whose transfer function is almost constant. And the eyes
The modulation element 7a includes an objective optical system as shown in FIG.
6, the optical axis is the Z axis, and the X and Y axes are in a plane orthogonal to the Z axis.
Then Z = A (X ^Three + Y ^Three ) Free-form surface
In this embodiment, it is assumed that A = 0.051.
You. FIG. 2 shows the image pickup unit 20 shown in FIG.
Table 1 shows the lens data. The focal length of this optical system is 1.
61mm, F-number is 8.722, aperture stop
8 is on the sixth surface, and the free-form surface of the pupil modulator 7a is on the seventh surface.
Equivalent to. [Table 1] As shown in FIG. 3A, the aperture stop 8 has a square opening.
It has a mouth shape with a side of 0.408 mm.
Also, the X axis of the pupil modulation element 7a and the square of the aperture stop 8
One side of the opening is arranged to be parallel. Further, the X axis of the pupil modulation element 7a is fixed.
Horizontal (scanning) direction of the pixel array of the body image sensor 5 (on the monitor
And the Y-axis of the solid-state imaging device 5
In the vertical direction (perpendicular to the scanning direction) of the pixel
(Vertical direction) and parallel to the optical axis (Z axis).
It is positioned in the direction of rotation. The camera controller 2 operates as shown in FIG.
The image signal from the connected endoscope 1 to a digital signal
An A / D converter 9 for converting the digital signal into an image
A signal conversion unit 10 for converting the video signal into a signal;
D / A converter for converting to an analog signal that can be displayed by data 4
11 and a processing circuit 12 outside the depth of field.
You. The processing circuit 12 outside the depth of field is shown in FIG.
Not according to operation signal from user interface, before
A control circuit for determining whether to apply image processing to the video signal
Path 25 and cut off the video signal according to the judgment of the control circuit 25.
And a video signal from the switch 26.
To perform processing corresponding to the pupil modulation element 7a
And an image processing circuit 27. The image processing circuit 27 filters the video signal.
This is a circuit for performing data processing, for example, when the object distance is 3 mm to 4 mm.
of light by the objective optical system 6 including the pupil modulation element 7a in mm
Response of the biological transfer function and the pupil modulation element 7a
Image processing for restoring asymmetric aberration (blur) generated
It is to do the processing. Here, if the response of the optical transfer function is
Use filter processing to restore asymmetrical aberrations
The optical transfer function of the objective optical system 6 and the pupil modulation element 7a is
Calculated by simulation and based on the results
You just need to do it. Restore optical transfer function response
For example, when using a digital circuit,
Using an asymmetric digital filter corresponding to the tuning element 7a
Can be (Operation) Pupil modulation element 7a having the above-mentioned shape
Is exp {i for parallel light having a wavelength of 587.56 nm.
× 2.414 (X ^Three + Y ^Three ) /0.204 ^Three } Phase modulation
Do. First, a diagram having no processing circuit outside the depth of field
The camera controller 117 shown in FIG.
Out-of-field processing circuit mounted in the controller 2
When the image processing by the image processing circuit 27 is not performed in step 12,
The case will be described. The object to be observed is the pupil modulation element 7a.
Through the objective optical system, including the solid with the pixel pitch of 7 μm
An image is formed on the light receiving surface on the image sensor 5 and the solid-state image sensor 5
Is converted into an electric signal (image signal). The electrical signal is
A / D conversion in camera controller 2 (or 117)
The signal is converted into a digital signal by the converter 9,
Is converted to a video signal. The video signal is a D / A converter
11 converts to analog signal that can be displayed on monitor 4
Then, the subject is displayed on the monitor 4. With respect to the imaging unit 20, an object distance of 1
Point image on the light receiving surface of the solid-state imaging device 5 at a position of 3.5 mm
Make the area of the intensity distribution function (PSF) the smallest
The focus was adjusted. The object distance at this time is 71 m
m, 13.5 mm, 7.2 mm, 4 mm, 3 mm
Point image on the light receiving surface of the solid-state imaging device 5 and each object
About the response of the optical transfer function on the optical axis at body distance.
Using the optical simulation software Code-V (product name)
And did the calculations. As a result, the solid-state image sensor at each object distance
The area of the point image on the photodetector surface is 22 μm on each side.
m, 14 μm, 20 μm, 31 μm, 50 μm
It was obtained as a point image of a size within a rectangular area. The point image
The light receiving surface of the solid-state imaging device is set to an XY plane, and each pixel is
FIG. 5 shows the results obtained when the intensity (percent) of light in the Z-axis is used.
To FIG. Also, the optics on the optical axis at each object distance
FIG. 10 shows the calculation result of the response of the dynamic transfer function. FIG. 5 shows a pupil modulator according to the first embodiment.
Obtained when the object distance of the imaging unit including the child is 71 mm
Figure for explaining the simulation result of the point image
is there. FIG. 6 includes a pupil modulation element according to the first embodiment.
Obtained at an object distance of 13.5 mm in the imaging unit
FIG. 9 is a diagram for explaining a simulation result of a point image.
You. FIG. 7 includes a pupil modulation element according to the first embodiment.
Points obtained when the object distance in the imaging unit is 7.2 mm
FIG. 9 is a diagram for explaining a simulation result of an image.
FIG. 8 shows an imaging including a pupil modulation element according to the first embodiment.
Spot image spots obtained when the object distance at the unit is 4 mm
FIG. 9 is a diagram for explaining a simulation result. FIG.
Imaging unit including pupil modulation element showing first embodiment
Simulation of point images obtained when the object distance is 3 mm
FIG. 9 is a diagram for explaining the result of the installation. Figure 10 shows these
Of the optical transfer function on the optical axis at various object distances
FIG. 9 is a diagram for explaining a calculation result of FIG. In FIGS. 5 to 9, the XY plane is a solid-state image sensor.
It corresponds to the light receiving surface of the element, and the Z axis is the light intensity (percent).
is there. Here, the X axis indicates the pixel numbers of 1, 2, 3,.
, And the Y axis indicates the pixel number by 1, 2, 3,....
Note that the XYZ axes have the same meaning in FIGS.
The taste. In FIG. 10, A is an object distance of 71 m.
m and B are an object distance of 13.5 mm, and C is an object distance of 7.2 m
m and D are when the object distance is 4 mm, and E is when the object distance is 3 mm.
The response of each optical transfer function. In addition,
The same applies to FIG. When the object distance is 13.5 mm, the point image is
One side is a 14 μm square area, that is, a pixel pitch of 7 μm
One side of the solid-state imaging device 5 is equivalent to 2 pixels and 4 pixels in area.
And a point image having a light intensity distribution shown in FIG.
Is obtained. Also, the object distance is 71 mm, 7.2 m
m, 4 mm, and 3 mm, each side image has 2 sides.
2 μm, 20 μm, 31 μm, 50 μm, that is, one side
Are 3.1 pixels, 2.9 pixels, 4.4 pixels, 7.1
5 and 7 to 9 in a square area corresponding to pixels.
Obtained as a point image having a light intensity distribution. Further, a solid-state image pickup device having a pixel pitch of 7 μm
5, the Nyquist frequency is 71 line pairs / mm.
However, as shown in FIG. 10, the object distance is 4 mm.
Of the optical transfer function at the Nyquist frequency in Japan
It can be seen that the resolution is 0.2 or more, and resolution is achieved.
When the object distance is 3 mm, the Nyquist frequency
The response of the optical transfer function at
Is not resolved. As a comparative example, the imaging unit 20 shown in FIG.
The pupil modulation element 7a is replaced by a parallel plate made of the same material.
The case of a normal optical system will be described. The ordinary optical system
The lens data of Table 7 shows the shape of the seventh surface in Table 1
It has been changed to a surface. The pupil modulation element 7a is arranged
Object distance 1 as in the case of
A point on the light receiving surface of the solid-state imaging device 5 at a position of 3.5 mm
The area of the image intensity distribution function (PSF) is the smallest
The focus was adjusted as follows. The object distance at this time is 71 m
m, 13.5mm, 7.2mm, 4mm
The point image on the light receiving surface of the body image sensor 5 and each object distance
The response of the optical transfer function on the optical axis of
Calculation using simulation software Code-V (product name)
Was performed. As a result, the solid-state image sensor at each object distance
The area of the point image on the photodetector surface is 16 μm on each side.
m, 1 μm, 14 μm, 36 μm
Was obtained as a point image of the size. Solid for the point image
The light receiving surface of the image sensor is an XY plane, and the light intensity at each pixel is
FIG. 11 to FIG. 1 show the results in which the degree (percent) is set on the Z axis.
It is shown in FIG. In addition, the optical transmission function on the optical axis at each object distance
The response of the numbers is shown in FIG. FIG. 11 shows an image pickup in a normal objective optical system.
Of point images obtained when the object distance of the unit is 71 mm
FIG. 9 is a diagram for explaining a simulation result. FIG.
Is the object distance of the imaging unit in a normal objective optical system.
Simulation of point image obtained at 13.5 mm separation
It is a figure for explaining a result. FIG. 13 shows a normal objective.
The object distance of 7.2 mm in the imaging unit in the optical system
Explain the simulation results of point images that are sometimes obtained.
FIG. FIG. 14 shows an image taken by a normal objective optical system.
Of point images obtained when the object distance in the image unit is 4 mm
FIG. 9 is a diagram for explaining a simulation result. FIG.
In A, A is the object distance of 71 mm, and B is the object distance of 13.
5mm, C is 7.2mm object distance, D is 4mm object distance
Is the response of the optical transfer function at the time. When the object distance is 13.5 mm, the point image is
A square area with one side of 1 μm, that is, a fixed area with a pixel pitch of 7 μm
One side of the body image sensor corresponds to one pixel, and the area corresponds to one pixel.
A point image having the light intensity distribution shown in FIG.
Obtained. Also, the object distance is 71 mm, 7.2 mm,
The point images in the case of 4 mm are 16 μm on one side and 14 μm on each side.
μm, 36 μm, that is, 2.3 pixels on one side, 2 pixels
11 and 1 in a square area corresponding to 5.1 pixels.
Obtained as point images having light intensity distributions shown in 3 and 14.
It is. Further, as shown in FIG.
Response of the optical transfer function at 0.2 GHz
Becomes that the object distance is not less than 7.2 mm and less than 71 mm
It turns out that it is. Next, the endoscope 1 including the pupil modulation element 7a is
Camera controller having out-of-field processing circuit 12
Connecting to 2 and further expanding the depth of field
explain. The object distance to the subject is less than 4 mm
When resolution is no longer possible, the endoscope operator
User (not shown) such as flash switch and foot switch
When the switching operation is performed via the interface,
Control signal from control circuit 25 in processing circuit 12 outside the depth of field
Switch 26 connects the video signal to image processing circuit 27
Work to do. Pupil modulation when the object distance is 3mm to 4mm open
Of the optical transfer function by the objective optical system 6 including the element 7a.
Sponge and non-light generated by the pupil modulator 7a.
Image processing configured to restore symmetric aberrations (blur)
The circuit 27 is configured to apply an optical signal to the unresolved video signal.
Response of the biological transfer function is 0.2 or more and asymmetric
Works to reduce various aberrations. The restored video signal
Is an image resolved on the monitor 4 through the D / A converter 11.
It is displayed as an image. (Effect) As described above, the pupil modulator 7a
Is replaced with a conventional endoscope 111 (see FIG. 30)
When connected to the camera controller 117 (see FIG. 30)
If the object distance is closer than 7.2 mm, the Nyquist circumference
Response of optical transfer function at wave number from 0.2
It is not resolved because it is lower. On the other hand, pupil modulation in the present embodiment
The endoscope 1 including the element 7a is replaced with a conventional camera controller 1
17 (see FIG. 30), when the object distance is 4 mm
Also the response of the optical transfer function at the Nyquist frequency
Resolution is greater than 0.2
You. Further, the phase change by the pupil modulation element 7a is performed.
The adjustment amount α is set to a sufficiently small value of 2.414.
Therefore, the response of the optical transfer function is 0.2 or more.
Generated by the pupil modulation terminal 7a within a given depth of field.
Asymmetrical aberration (blur) is at most several pixels
Symmetric aberration is at a level that cannot be recognized on the monitor 4.
For this reason, a special image processing circuit is not required.
Also, it can be seen that the depth of field is expanded. Further, the pupil modulation element in the present embodiment
The endoscope 1 including the endoscope 7a includes a processing circuit 12 outside the depth of field.
When connected to the camera controller 2
Optical transfer function at object distance less than 4 mm by path 27
Response can be restored.
Resolution of less than 4 mm apart and asymmetrical aberration (blur)
It is possible to obtain a small image. With this,
Can increase the depth of field and improve image quality
It works. Here, in the present embodiment, the solid-state imaging device
Pixel pitch of 7μm, but limited to this
Instead, the area of the point image on the light-receiving surface of the solid-state
The size of the point image at the bin position
The side is equivalent to two pixels of the pixel pitch and the area is equivalent to four pixels
The aperture size of the aperture stop 8 and the pupil modulation element 7a
By adjusting the shape of the
It works. Further, in this embodiment, the solid-state image pickup device
Focus point where the area of the point image on the
The size of the point image to be projected is determined by the pixel pitch of one side of the solid-state
Was adjusted to be 2 pixels and 4 pixels in area.
Or, the size of the point image should be
If the product is 36 pixels, the pupil modulation element
Has a modulation coefficient α of 7.243 at an object distance of 4 mm
The response of the optical transfer function is 0.2 or more, and
The size of a point image at an object distance of 4 mm is about 8 pixels on one side
Degree, the same depth of field is possible.
You. In this embodiment, the pupil modulator 7a is made of glass.
Although a material is used, a resin material may be used. Also,
In the present embodiment, the pupil modulation element 7a is an optically transparent glass.
Optical fiber that transmits only specific wavelengths
A filter material may be used. The pupil modulation element 7a according to the present embodiment
The shape is the conversion amount of the optical transfer function in the X-axis direction and the Y-axis direction.
The conversion amount is different in the X-axis direction and the Y-axis direction.
May be adopted. For example, the aperture shape of the aperture stop 8
May be set to a rectangle, or the free tune of the pupil modulation element 7a.
Use different coefficients for the surface shape in the X-axis direction and Y-wheel direction.
Is also good. The same applies to the case where the aperture stop 8 is circular.
The same effects can be obtained. In this case, the aperture stop 8 and the pupil change
It is not necessary to adjust the rotation direction with respect to the optical axis with the adjusting element 7a.
There is an effect that. The aperture stop 8 is a pupil modulation element.
It does not have to be separate from 7a.
It may be formed more directly. FIG. 16 shows a second embodiment of the present invention.
Camera controller (signal processing device) according to the embodiment
FIG. 3 is a block diagram illustrating a configuration of (a). (Structure) The second embodiment is similar to the first embodiment.
Since it is almost the same as the form, only the differences are explained
The same components are denoted by the same reference numerals, and description thereof is omitted. In this embodiment, the basic configuration is the first embodiment.
The signal processing in the camera controller is the same as that of the embodiment.
The logic circuit is different. The following description focuses on the differences.
You. FIG. 16 shows a camera according to the second embodiment.
FIG. 2 shows a schematic diagram of a controller. The camera controller 2a of the present embodiment
Has a configuration as shown in FIG. 16 and is connected to an endoscope.
A / D conversion for converting an image signal from 1 into a digital signal
And a signal converter for converting the digital signal into a video signal.
Conversion unit 10 and an analyzer capable of displaying the video signal on the monitor 4.
D / A converter 11 for converting to a log signal, and brightness of the subject
Automatic dimming control for controlling the amount of light emitted from the light source device 3 according to the
Road 31 and the processing circuit 12a outside the depth of field
I have. The processing circuit 12a outside the depth of field has an automatic light control.
The distance to the object is determined from the dimming signal from the circuit 31,
Control for determining whether to perform image processing on the video signal
The circuit 25 and the control circuit 41 determine that the video signal is turned off.
A switching unit 26 for performing switching, and an image from the switching unit 26
Processing corresponding to the pupil modulation element 7a is performed on the signal
An image processing circuit unit 32 having a plurality of image processing circuits
Is done. The image processing circuit section 32 processes the video signal
It is a circuit part that performs filter processing, and changes the pupil according to the object distance.
Of the optical transfer function by the objective optical system 6 including the tuning element 7a
Response and generated by the pupil modulation element 7a
Performs image processing to restore asymmetric aberration (blur)
is there. For example, in the present embodiment, the image processing
In the logic circuit section 32, the object distance between 3 mm and 4 mm is restored.
Image processing circuit 32a, object distance between 2 mm and 3 mm
Processing circuit 32b for restoring the object, object distance 71 mm or more
An image processing circuit 32c for restoring is provided. Here, if the response of the optical transfer function is
Use filter processing to restore asymmetrical aberrations
At each object distance by the objective optical system 6 and the pupil modulation element 7a
Optical transfer function is calculated by simulation, and
What is necessary is just to create based on the result of. (Operation) Endoscope 1 including pupil modulation element 7a
A camera controller having a processing circuit 12a outside the depth of field.
Connected to the roller 2a to increase the depth of field.
Will be explained. The signal conversion section 10 outputs a luminance signal as a video signal.
Y and two color difference signals RY and BY are generated. Automatic adjustment
The optical circuit 31 compares the luminance signal Y with the reference signal level.
And the amount of light emitted from the light source device 3 according to the magnitude of the luminance signal Y.
To generate a dimming signal for controlling The control circuit 25 operates based on the dimming signal.
The body distance is determined, and the switch 26 is controlled to output the video signal to the object.
Connected to the image processing circuit of the image processing circuit unit 32 according to the distance
Work to do. The video signal is sent to the image processing circuit 32.
Is subjected to the desired restoration process, and
It is projected on 4. First, the object distance is longer than the depth of field.
The case will be described in detail. Object distance or far away
Automatic dimming when the level of the luminance signal Y decreases due to the foot
The circuit 31 instructs the light source device 3 to increase the amount of emitted light.
Generate a signal. This dimming signal is connected to the light source device 3.
Connected to the control circuit 25,
The road 25 determines that the object distance has increased, and
26 to restore the video signal to an object distance of 71 mm or more
It is connected to the image processing circuit 32c of the image processing circuit unit 32. Then, the object distance is long and the optical transfer function
Of the video signal whose response has decreased
The restoration processing corresponding to the object distance of 71 mm or more by c
And restored to the resolved video. Next, when the object distance is shorter than the depth of field,
The case will be described in detail. The object distance is short and the illumination light is
If the luminance signal Y is too strong and rises to a level near the saturation level
In this case, the automatic light control circuit 31 sends a decrease in the amount of emitted light to the light source device 3.
Generates an instructed dimming signal. After receiving this dimming signal,
The control circuit 25 determines that the object distance is short, and switches.
The video signal is converted from the object distance of 3 mm to 4 mm
It is connected to the image processing circuit 32a to be restored. Then, as the object distance becomes shorter, the optical
The response of the transfer function decreases and can be recognized on the monitor 4.
The video signal with a large degree of asymmetric aberration (blurring)
Object distance 3 mm to 4 mm by image processing circuit 32a
Is restored to the resolved video.
You. Further, regarding the case where the object distance approaches
explain in detail. The object distance becomes even closer and the luminance signal
If the level of Y further rises, the automatic dimming circuit 34
A bright light signal for instructing further reduction of the output light amount is generated.
Upon receiving the dimming signal, the control circuit 25 further increases the object distance.
It is determined that the distance has come close, and the video signal is
Image processing circuit 32b for restoring 3 mm from 2 mm body distance
Connect to Then, the object distance is restored from 3 mm to 4 mm.
Optical transmission function that cannot be restored by the image processing circuit 32a
Number response decreased, asymmetric aberration (blur) occurred
For the video signal, the image processing circuit 32b has an object distance of 2 mm
To 3mm from the original image
Restore. (Effect) As described above, the endoscope system
Distance using an automatic dimming circuit generally prepared in Japan
Detection means and restoration processing according to the distance
Depth of field without the need for operation by the endoscope operator
Can be expanded. In addition, multiple
Number of restoration processes, so that
Improvement is possible. In this embodiment, the detection of the object distance is not performed.
This was performed using an automatic light control signal.
Distance measuring sensor that irradiates
A sensor may be used. In this case, accurate ranging is possible
And that the optimal image processing circuit can be reliably selected.
effective. The output of the video signal in the high frequency range is maximum.
The image processing circuit is switched so that
A method of selecting a processing circuit may be used. In this case,
The image processing circuit is selected so that the
Therefore, an effect of improving image quality can be expected. Further, the plurality of distance measuring means are combined.
To select the optimal image processing circuit
Becomes possible. In this embodiment, the image processing circuit is remote.
One type on the point side and two types on the near point side, but limited to this
Instead, multiple image processing circuits are provided according to the object distance
May be. Similarly, the image processing circuit in this case also has the object distance
Calculation of the optical transfer function according to the simulation
Then, it may be created based on the result. Further, in the present embodiment, a pupil modulation element is included.
One type of image processing circuit was described.
Is compatible with an objective optical system that includes multiple types of pupil modulation elements.
If an image processing circuit is provided in the camera controller,
For various types of endoscopes, the depth of field and the image quality
The above can be realized. At this time, it is mounted on the endoscope
Image processing corresponding to the objective optical system including the pupil modulator
Discriminating means for discriminating the type of each endoscope for selecting a road
Is provided to connect each endoscope to the camera controller.
When you continue, be sure to select the optimal image processing.
You can also. [Appendix] (Appendix 1) An optical image of the objective optical system is taken by a solid-state imaging device.
Multiple types of endoscopes for imaging and signals from the solid-state imaging device
Signal processing to convert video into video signals that can be displayed on a monitor
Electronic endoscope system used in combination with
In a stem, at least one endoscope objective light
The optical system has an optical phase modulation mask and the optical phase modulation mask.
The change in the optical transfer function according to the object distance is
Smaller than objective optics without optical phase modulation mask
And the signal processing device is arranged to
Optical transfer function modified by the optical phase modulation mask
Of the optical transfer function
Characterized in that it has a restoration processing means for processing
Endoscope system. In the electronic endoscope system according to the additional item 1, the light position
The objective optical system having the phase modulation mask is an optical phase modulation mask.
Object than the depth of field of the objective system without
The change of the optical transfer function according to the distance is reduced.
Works. An objective optical system having the optical phase modulation mask;
The image signal from the solid-state imaging device of the endoscope used is
In response to the separation, the light is restored by the restoration
Is projected on the screen. This makes it optimal for object distances
Image quality is obtained. (Appendix 2) The optical phase modulation mask is provided.
The response of the optical transfer function of the objective optical system is
When the objective optical system has no optical phase modulation mask,
The solid-state imaging over an object distance greater than the depth of field
Response is 0.2 or more up to the element's text frequency.
3. The electronic endoscope system according to claim 1, wherein
M In the electronic endoscope system according to additional item 2, the light position
Depending on the phase modulation amount of the phase modulation mask, the normal objective optical system
Optics modified by optical phase modulation mask compared to
Response of the solid-state image sensor is Nyquist
Since it is 0.2 or more up to the frequency, it can be used with a normal objective optical system.
Compare and resolve over a wide depth of field. This
Endoscope using an objective optical system with an optical phase modulation mask
An image processor that performs inverse conversion of the optical phase modulation mask also in the mirror
Signal processor for general endoscope systems
Connection is possible. (Additional Item 3) The solid-state imaging device receiving a point image
At the object distance where the area on the light surface is the smallest,
The point of the objective optical system of the endoscope having the optical phase modulation mask
The area W of the image on the light receiving surface of the solid-state image sensor is
When the pixel pitch of the child is P, W ≦ 36 × P ^Two Satisfies the following items.
Child endoscope system. In the electronic endoscope system according to additional item 3, the light position
The optical phase modulation mask depends on the phase modulation amount of the phase modulation mask.
Image sensor receiving optical transfer function of objective optical system
The area W of the point image on the light surface is W ≦ 36 × P ^Two It becomes. this
The optical system of the objective optical system having the optical phase modulation mask
The response of the transfer function is fixed over a wide range
It is 0.2 or more up to the Nyquist frequency of the body image sensor.
In addition, asymmetric blur caused by the optical phase modulation mask
Is only a few pixels of the solid-state
Optical transfer functions such as asymmetric digital filters
No original means is required. (Additional Item 4) The optical phase modulation mask is
When the optical axis of the objective optical system is the Z axis,
When the two axes are X and Y, the light having a wavelength of 587.56 nm
For exp {i × α (X ^Three + Y ^Three )} (However, | X | ≦ 1, |
Y | ≦ 1), and the coefficient α is 8 or less.
Any of the additional items 1, 2 and 3 characterized in that
3. The electronic endoscope system according to claim 1. In the electronic endoscope system according to additional item 4, the light position
The phase converted by the phase modulation mask is
When the optical axis of the system is the Z axis, two axes orthogonal to each other are X,
Assuming that Y is ex for light having a wavelength of 587.56 nm,
p {i × α (X ^Three + Y ^Three )}, The coefficient α is 8 or less.
You. Due to this, it was changed by the optical phase modulation mask
Response of optical transfer function or Nyquist of solid-state image sensor
Up to a frequency of 0.2 g. (Appendix 5) Nike of the solid-state imaging device
The response of the optical transfer function is 0.
At an object distance of 2 or more, it depends on the phase modulation mask.
Without performing the optical transfer function restoration process,
At an object distance where the number response is less than 0.2,
A plurality of optical transfer function restoration processes according to the object distance;
3. The electronic endoscope system according to claim 2, wherein
Tem. In the electronic endoscope system according to additional item 5,
The optical transmission function up to the Nyquist frequency of the solid-state imaging device
At object distances where the number response is greater than 0.2, the optical phase
Without performing the optical transfer function restoration means according to the modulation mask,
An optical transfer function having a response less than 0.2.
In body distance, optical transfer function restoration according to the object distance
Perform processing. Light the endoscope having the optical phase modulation mask
Connected to a signal processing circuit that does not have
If so, the depth of field is increased. Further, the optical phase
Has optical transfer function restoration means corresponding to the modulation mask
When connected to a signal processing circuit, the depth of field can be further expanded.
Larger and higher resolution image quality can be obtained. (Appendix 6) The optical image of the objective optical system is
A plurality of types of endoscopes for imaging with an imaging device, and the solid-state imaging
Converts signals from devices to video signals that can be displayed on a monitor
Used in combination with multiple signal processing devices
In a Ryuko endoscope system, at least one endoscope is provided.
Has an optical phase modulation mask, and the optical phase
Modulation mask changes optical transfer function with object distance
Is less than the objective optical system without the optical phase modulation mask.
The optical phase modulation mask acts so as to be small.
Of the optical transfer function of the objective optical system having
Is an objective optical system having no optical phase modulation mask
Over an object distance greater than the depth of field of the solid
Response is 0.2 or less up to the Nyquist frequency of the image sensor
And the signal processing device is configured to
For the optical transfer function modified by the modulation mask,
Performing multiple optical transfer function restoration processes according to body distance
Source processing means, wherein the restoration processing means
Response of the optical transfer function up to the Nyquist frequency of the
At an object distance where the
The optical transfer function is not restored according to the
Distance where the response of the dynamic transfer function is less than 0.2
A plurality of optical transfer function decoding according to the object distance.
An electronic endoscope system characterized by performing original processing. In the electronic endoscope system according to the additional item 6, the light position
The objective optical system having the phase modulation mask is an optical phase modulation mask.
Than the depth of field of a normal objective without
The change of the optical transfer function according to the distance is reduced.
Works. Before the Nyquist frequency of the solid-state imaging device
Object distance with an optical transfer function response of 0.2 or more
In the separation, optical transfer function restoration according to the optical phase modulation mask
No measure is taken, and the response of the optical transfer function is 0.
At an object distance of less than 2, the optics corresponding to the object distance
Subject to dynamic transfer function restoration processing. Having the optical phase modulation mask
Signal processing without optical transfer function restoring means.
When connected to a physical circuit, the depth of field is increased. Further
The optical transfer function corresponding to the optical phase modulation mask
If connected to a signal processing circuit with
The depth of field can be increased, and a high-resolution image can be obtained. (Additional Item 7) Including the optical phase modulation mask
The aperture shape of the aperture stop used in the objective optical system is circular.
The item described in Appendix 1 or 6
On-board electronic endoscope system. (Appendix 8) Object Distance for Detecting Object Distance
Separation detecting means, wherein the restoration processing means detects the object distance.
Switch according to the object distance detected by the
Having a plurality of optical transfer function restoration processing circuits
7. The electronic endoscope according to claim 1 or 6, characterized in that:
system. In the electronic endoscope system according to additional item 8, the object
Optics automatically according to object distance by distance detection means
Special operation because the selective transfer function restoration processing circuit is selected
It is possible to increase the depth of field and improve image quality without the need for
You. (Additional Item 9) The object distance detecting means may include:
For automatic dimming using the image signal from the solid-state image sensor
It is a means to detect the distance by the dimming signal of
9. The electronic endoscope system according to claim 8, wherein In the electronic endoscope system according to additional item 9, the object
By utilizing the relationship between distance and brightness, a general endoscope system can be used.
Detects object distance using automatic light control mounted on the
You. (Appendix 10) Output of high frequency range of image pickup signal
Restoring the plurality of optical transfer functions so that the force is maximized
Item 8 is characterized in that the processing circuit is switched.
Electronic endoscope system. In the electronic endoscope system according to the additional item 10, imaging is performed.
The optical transmission function is designed to maximize the output of the image signal in the high frequency range.
Switching of the number restoration processing circuit makes it possible to obtain high-quality video.
It is. The present invention is limited to the above embodiment.
It does not change the gist of the present invention.
Thus, various changes and modifications can be made. According to the present invention as described above,
Restoration processing according to the optical phase modulation mask arranged in the endoscope optical system
Phase modulation in a signal processor without
Even if an endoscope with a mask is connected, the depth of field will increase.
Large and high-resolution images can be generated, and optical phase shift
Restoration processing means according to the tone mask
Endoscope with optical phase modulation mask
The depth of field, and the height
There is an effect that a resolution image can be generated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a schematic configuration of an endoscope system according to a first embodiment of the present invention. FIG. 2 is a diagram showing an imaging unit including an optical phase modulation mask of FIG. FIG. 3 is a schematic diagram for explaining the structure of the pupil modulation element in which the brightness stop of FIG. 2 is arranged. FIG. 4 is a diagram showing the structure of the camera controller (signal processing device) of FIG. FIG. 5 is a diagram illustrating a simulation result of a point image obtained when the object distance of the imaging unit including the pupil modulation element of FIG. 2 is 71 mm. FIG. 6 is an imaging including the pupil modulation element of FIG. FIG. 7 is a diagram for explaining a simulation result of a point image obtained when the object distance of the unit is 13.5 mm. FIG. 7 is a point image obtained when the object distance of the imaging unit including the pupil modulation element of FIG. 2 is 7.2 mm. The simulation results of FIG. 8 is a diagram for explaining a simulation result of a point image obtained when an object distance of an imaging unit including the pupil modulation device of FIG. 2 is 4 mm. FIG. 9 is a diagram illustrating the pupil modulation device of FIG. FIG. 10 is a diagram for explaining a simulation result of a point image obtained when the object distance of the imaging unit including the imaging unit is 3 mm. FIG. 10 is a simulation of a response of an optical transfer function of each object distance of the imaging unit including the pupil modulation element of FIG. FIG. 11 is a diagram for explaining a result. FIG. 11 is a diagram for explaining a simulation result of a point image obtained when the object distance of the imaging unit in FIG. 2 is 71 mm in a normal optical system. FIG. 13 is a diagram for explaining a simulation result of a point image obtained when the object distance of the imaging unit in FIG. 2 is 13.5 mm. FIG. 14 is a diagram for describing a simulation result of a point image obtained when the object distance of the image unit is 7.2 mm. FIG. 14 is a diagram illustrating a point image obtained when the object distance of the imaging unit in FIG. 2 is 4 mm in a normal optical system. FIG. 15 is a diagram illustrating a simulation result. FIG. 15 is a diagram illustrating a simulation result of a response of an optical transfer function with respect to each object distance of the imaging unit in FIG. 2 in a normal optical system. FIG. 17 is a block diagram illustrating a configuration of a camera controller (signal processing device) according to a second embodiment. FIG. 17 is a diagram schematically illustrating a configuration of an enlarged depth of field optical system according to a conventional example. FIG. 19 is a view for explaining the external shape of a cubic phase modulation mask. FIG. 19 is an optical transfer function (OTF) when an object is at a focal position in a normal optical system. FIG. 20 is a graph showing a response of an optical transfer function (OTF) when an object deviates from a focal position in an ordinary optical system. FIG. 21 is a graph showing an object from a focal position in an ordinary optical system. The optical transfer function (O
FIG. 22 is a graph showing a response of an optical transfer function (OTF) when an object is at a focal position in an enlarged depth-of-field optical system. FIG. 23 is an enlarged depth-of-field optical system. FIG. 24 is a graph showing the intensity distribution of the optical transfer function (OTF) when the object deviates from the focal position in FIG. 24. FIG. 24 shows when the object deviates further from the focal position in the enlarged depth of field optical system than in FIG. FIG. 25 is a graph showing the response of the optical transfer function (OTF) of FIG. 25. FIG. 25 is a graph showing the characteristics of the inverse filter of the processing performed on the response of the optical transfer function (OTF) in the enlarged depth of field optical system. 26. The optical transfer function (OTF) obtained by subjecting the response of the optical transfer function (OTF) of FIG. 22 to processing by an inverse filter having the characteristics of FIG. FIG. 27 is a graph showing the response of the optical transfer function (OTF) obtained by performing the processing of the optical transfer function (OTF) of FIG. 23 with the inverse filter having the characteristics of FIG. 28 is a graph showing the response of the optical transfer function (OTF) obtained by performing the processing of the optical transfer function (OTF) of FIG. 24 using the inverse filter having the characteristics of FIG. 25 on the response of the optical transfer function (OTF). FIG. 30 is a block diagram showing a schematic configuration of a conventional endoscope system for connecting a plurality of types of endoscopes and observing an image of a subject on a monitor. FIG. 30 is a block diagram showing a configuration of a conventional camera controller in FIG. 1 [Endoscope 2] Camera controller (signal processing device) 3 [Light source device 4] Monitor 5 [Solid-state image sensor 6] Objective optical system 7 [Phase modulation mask 7a] ... pupil modulation element 8 ... brightness stop 9 ... A / D converter 10 ... signal converter 11 ... D / A converter 12 ... depth of field processing circuit 20 ... imaging unit 25 ... control circuit 26 ... switch 27 … Image processing circuit agent Patent Attorney Susumu Ito

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/225 H04N 5/225 C 7/18 7/18 M (72) Inventor Hiroshi Ishii Shibuya-ku, Tokyo 2-43-2 Hatagaya Olympus Optical Co., Ltd. (72) Inventor Riki Hirai 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olimpus Optical Co., Ltd. (72) Inventor Jun Hiroya Shibuya-ku, Tokyo 2-43-2, Hatagaya Olympus Optical Co., Ltd. (72) Inventor Hisao Yabe 2-43-2, Hatagaya, Shibuya-ku, Tokyo F-term in Olympus Optical Co., Ltd. 2H040 BA01 CA22 CA23 GA02 2H087 KA10 LA01 PA03 PA18 PB04 QA01 QA07 QA18 QA21 QA25 QA37 QA41 QA45 RA42 RA43 4C061 BB01 CC06 FF40 HH28 LL02 NN05 PP11 SS21 TT12 5C022 AA09 AC51 5C054 CC07 EH00 HA12

Claims (1)

Claims: 1. A plurality of types of endoscopes for capturing an optical image of an objective optical system with a solid-state imaging device, and converting a signal from the solid-state imaging device into a video signal that can be displayed on a monitor. In an electronic endoscope system connected and used in combination with a plurality of signal processing devices, at least one objective optical system of the endoscope has an optical phase modulation mask, and the optical phase modulation mask is The change in the optical transfer function according to the object distance is arranged to act so as to be smaller than the objective optical system without the optical phase modulation mask, and the signal processing device is changed by the optical phase modulation mask. An electronic endoscope system, comprising: restoration processing means for performing a plurality of optical transfer function restoration processes according to an object distance on the optical transfer function.