JP5624955B2 - Endoscope device - Google Patents

Description

  The present invention relates to an endoscope apparatus having an autofocus function.

In recent years, endoscopes equipped with an imaging unit using a solid-state imaging device have been widely used in the medical field.
In the case of endoscopy, there have also been proposed endoscopes equipped with an optical system with an autofocus function and an imaging unit using a solid-state imaging device with high pixels so that the affected area can be observed in detail. Yes.
For example, the conventional example of Japanese Patent Application Laid-Open No. 2002-253489 discloses an endoscope apparatus that autofocuses by moving some lenses in an objective optical system, and switches a subject distance that can be focused. When the enlargement control means is activated by the operation of the switching means, the focus control of the objective optical system is adjusted on the long focal length side of the variable focal length range of the objective optical system by the focus control means that is activated in conjunction with the control signal of the enlargement control means. Has been done.

Japanese Patent Laid-Open No. 2002-253489

However, in the case of observing close to an affected part or the like, in the above conventional example, the focal length becomes long, so that the depth of field depth (also simply referred to as depth width) becomes narrow, and the required depth width is reduced. Couldn't get. Further, in this conventional example, the field angle is narrowed when observing close to the affected part.
Therefore, an endoscope apparatus that can increase the depth range and obtain an image suitable for examination and observation with an endoscope is desired even when observing close to an affected area.

On the other hand, when observing close to an affected part or the like, there is a demand to increase the resolution beyond the depth width so that the affected part can be observed with high pixels (high definition).
The present invention has been made in view of the above-described points. It is an object of the present invention to provide an endoscope apparatus that can perform observation with a large depth range or a high resolution state when observing closely. To do.

  An endoscope apparatus according to an aspect of the present invention includes an imaging unit including an objective optical system and a solid-state imaging device at a distal end portion of an endoscope, and is used for a subject at an arbitrary distance within a predetermined distance range. In an endoscope apparatus that automatically performs focus control by moving a focus lens in the objective optical system so as to be in focus, the focus is automatically controlled for the subject within the predetermined distance range. Limiting means for limiting the area to at least two, selection means for manually selecting a limited focusing area for the limiting means, and simultaneous selection of the focusing area by the selecting means, the solid-state imaging device And a changing unit that cuts out a part of the imaging area from the imaging area on the imaging surface and changes the distance from the center position to the farthest position in the imaging area of the solid-state imaging device, By moving a moving lens different from the focus lens in the objective optical system, the angle of view of the imaging unit is set to be within 5% before and after the change of the imaging area by the changing means. It is characterized by doing.

  An endoscope apparatus according to another aspect of the present invention includes an imaging unit including an objective optical system and a solid-state imaging device at a distal end portion of an endoscope, and applies to an object at an arbitrary distance within a predetermined distance range. In an endoscope apparatus that automatically performs focus control by moving a focus lens in the objective optical system so as to be in focus, the focus control is automatically performed on the subject within the predetermined distance range. Limiting means for limiting the focus area to at least two, selection means for manually selecting a limited focus area with respect to the limiting means, and simultaneous selection of the focus area by the selection means, the solid-state imaging Changing the distance from the center position to the farthest position in the imaging area of the solid-state imaging device by enlarging the imaging area on the imaging surface of the element, and the objective By moving a moving lens that is different from the focus lens in the academic system, the angle of view of the imaging unit is set to be within 5% before and after the change of the imaging area by the changing means. It is characterized by.

  According to the endoscope apparatus according to one aspect of the present invention, it is possible to provide an endoscope apparatus capable of performing observation with an increased depth range, and an endoscope apparatus according to another aspect of the present invention. Therefore, it is possible to provide an endoscope apparatus that can perform observation in a high-resolution state.

FIG. 1 is a diagram showing an overall configuration of an endoscope apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating an imaging region in the solid-state imaging device. FIG. 3 is a cross-sectional view showing the configuration of the imaging unit. FIG. 4 is a cross-sectional view of the objective optical system in a state set to a first focal position to a fourth focal position. FIG. 5 is a block diagram illustrating a configuration in which a driving signal is limited to the actuator driving unit to limit the movable range by the focus lens to two. FIG. 6 is a diagram showing the relationship between the object distance and the resolving power in the state where each focal position in FIG. FIG. 7 is a flowchart showing a schematic operation of the first embodiment. FIG. 8 is an explanatory diagram when a peripheral image portion in an endoscopic image is cut out and displayed. FIG. 9 is a diagram illustrating a configuration of a light source device in the case of an imaging unit including a CCD having no color separation filter. FIG. 10 is a cross-sectional view of the objective optical system in a state set to a representative focal position in the second embodiment of the present invention. FIG. 11 is a diagram illustrating a characteristic example of the resolving power with respect to the object distance of the objective optical system in a state of being set to a representative focal position including the case of FIG. FIG. 12 is a cross-sectional view of the objective optical system in a state set to a representative focal position in the third embodiment of the present invention. FIG. 13 is a diagram illustrating a characteristic example of the resolving power with respect to the object distance of the objective optical system in a state where the representative focal position is set. FIG. 14 is a diagram showing an overall configuration of an endoscope apparatus according to the fourth embodiment of the present invention. FIG. 15 is a diagram illustrating an imaging region in a solid-state imaging device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 1, the endoscope apparatus 1 performs signal processing on an endoscope 2, a light source device 3 that supplies illumination light of the endoscope 2, and an imaging unit mounted on the endoscope 2. An image processing device (or signal processing device) 4 and a monitor 5 as display means for displaying an endoscopic image by inputting a standard video signal (image signal) output from the image processing device 4; Consists of
The endoscope 2 in this embodiment is provided with an elongated insertion portion 7 to be inserted into a subject and an operation portion 8 provided at the rear end of the insertion portion 7 and held and operated by an operator such as an operator. And a cable portion 9 extending from the operation portion 8.
The insertion portion 7 is provided with a hard distal end portion 11 at the distal end, and the distal end portion 11 is provided with an imaging unit 19 that forms an imaging means.

A bendable bending portion 12 is provided adjacent to the distal end portion 11, and the surgeon can bend the bending portion 12 in a desired direction by operating a bending operation knob (not shown) in the operation portion 8. it can.
A light guide 14 for transmitting illumination light is inserted into the insertion portion 7, and the rear end side of the light guide 14 reaches the light guide connector 15 provided at the end portion via the cable portion 9. By connecting the light guide connector 15 to the light source device 3, illumination light is supplied from the light source device 3 to the rear end surface of the light guide 14.
The light source device 3 has a lamp 3a as a light source for generating illumination light, and the light from the lamp 3a is condensed after the amount of transmitted light is adjusted by the opening of the diaphragm 3c driven by the diaphragm driver 3b. The light is incident on the incident end face of the light guide 14 in the light guide connector 15 through the lens 3d. The diaphragm driving unit 3b is driven to adjust the aperture amount of the diaphragm 3c, that is, the transmitted light amount based on a dimming signal described later.

The illumination light supplied from the light source device 3 is transmitted by the light guide 14 and emitted forward from the distal end surface fixed to the distal end portion 11 through the illumination lens 16 attached to the illumination window so as to face the distal end surface. Illuminate a subject such as an affected part in a body cavity.
The distal end portion 11 is provided with an observation window (or an imaging window) adjacent to the illumination window. In the imaging window, an objective optical system 17 that connects an optical image of the illuminated subject, and the objective optical system 17. An imaging unit 19 including, for example, a charge coupled device (abbreviated as CCD) 18 serving as a solid-state imaging device having an imaging surface (photoelectric conversion surface) disposed at the imaging position is disposed.
The CCD 18 in this embodiment is a mosaic color filter type CCD having a mosaic color filter 18a (see FIG. 4A) such as a complementary color system as a color separation filter for optically color separation.

One end of the signal cable 21 is connected to the imaging unit 19, and the signal cable 21 inserted into the insertion portion 7 is further inserted into the cable portion 9 and the other end is connected to the signal connector 22 at the rear end.
By connecting the signal connector 22 to the image processing device 4, the CCD 18 is driven by a CCD drive signal from a CCD drive unit 23 provided in the image processing device 4, and the CCD 18 outputs an imaging signal obtained by photoelectric conversion as an output signal. Output.
The imaging signal is subjected to signal processing in the image processing device 4 to generate a video signal, and an endoscopic image is displayed on the monitor 5.
In addition, a channel 25 that allows various treatment tools to be inserted is provided in the insertion portion 7.

Then, the surgeon can project the distal end side of the treatment instrument from the distal end opening 25b opened at the distal end part 11 by inserting the treatment instrument from the treatment instrument insertion port 25a in the vicinity of the front end of the operation unit 8. Tissues are collected and treatments such as excision can be performed.
In the present embodiment, the objective optical system 17 constituting the imaging unit 19 has a movable movable focus lens 26, and by moving the focus lens 26, inspection and observation can be performed using the endoscope 2. Focus control is performed automatically (automatically) so that a subject such as an affected part at an arbitrary distance within a predetermined distance range required for the observation can be observed in a focused state.

In the present embodiment, an angle-of-view lens 27 for adjusting the angle of view is provided in addition to the focus lens 26 as a movable moving lens in the objective optical system 17.
The imaging signal output from the CCD 18 is input to a correlated double sampling circuit (abbreviated as CDS circuit) 31 that forms a signal processing unit in the image processing apparatus 4, and after the CDS processing, a digital image is output by the A / D converter 32. It is converted into a signal and input to the image processing unit 33.
The image processing unit 33 includes a signal conversion circuit 33 a that converts an input signal into an image signal of a color signal C and a luminance signal Y, and outputs the luminance signal Y to the dimming signal generation unit 34. The dimming signal generation unit 34 generates a dimming signal and outputs it to the aperture driving unit 3 b of the light source device 3.

The digital image signal (video signal) output from the image processing unit 33 is converted to an analog image signal by the D / A converter 35 and then output to the monitor 5. An endoscopic image corresponding to the signal is displayed.
Further, the image processing unit 33 outputs the luminance signal Y to the contrast detection unit 36a of the CPU 36 that forms the control means. The contrast detection unit 36a configured by the CPU 36 detects the contrast of the image from the luminance value in the input luminance signal. The detected contrast is input to an autofocus control unit (AF control unit in FIG. 1) 36b of the CPU 36 and used for autofocus control.
The autofocus control unit 36b moves the focus lens 26 via the actuator driving unit 37, and automatically sets the objective optical system 17 to the in-focus state.

In this case, the autofocus control unit 36b sets the state where the contrast is the highest as the in-focus state of the objective optical system 17, and sets the autofocus so that the contrast of the image when the focus lens 26 is moved is set to the highest position. Take control.
In this embodiment, the focus lens 26 can be moved to effectively prevent a malfunction due to autofocus and to improve the autofocus speed (to set the focus state in a short time). For example, the actuator drive unit 37 is provided with a limiting unit 37a as a limiting unit that limits a plurality of ranges (abbreviated simply as a movable range), specifically, to two movable ranges.
The CPU 36 is provided with a control unit 36c as control means for controlling the operation of the limiting unit 37a.

  When the imaging unit 19 observes a subject (object) such as an affected part at an arbitrary distance within a predetermined distance range, it is necessary to move the focus lens 26 (the objective optical system 17) to be set in a focused state. The first movable range (far-point side movable range) for focusing the subject in the first region Ra (see FIG. 6) on the far-point side in the movable range of the focus lens 26. Only within one (one) movable range of Ka (see FIG. 3) and the second movable range (near-point-side movable range) Kb for focusing on the subject in the second region Rb on the near-point side. The focus lens 26 is limited (restricted) so that it can move, and the autofocus control can be performed. In FIG. 3, the movable ranges Ka and Kb are indicated by two moving ranges of the arm 44a that can move within the moving groove 43a.

Then, the control unit 36c of the CPU 36 sets the pixel pitch in the horizontal direction and the vertical direction of the CCD 18 to Pmm with respect to the movable range K in which the focus is automatically controlled so as to be in focus. When the range in which the MTF of the spatial frequency 1 / (3XP) on the optical axis is 10% or more is defined as the depth of field depth (simply the depth width), the depth width of one focusing zone is 10 mm or more. In addition, a boundary B (see FIG. 3) between the two movable ranges Ka and Kb is set in a range where the object distance of the objective optical system 17 is 15 mm or less.
The object distance corresponding to this boundary B is indicated by a dotted line Ba in FIG. 6, and the object distance in this case is around 10 mm. For example, when the focus state is set to the second focal position, the depth range is 10 mm to 26 mm (see numerical data described later).

Further, for example, the operation unit 8 in the endoscope 2 is provided with a selection switch (or changeover switch) SW1 that forms selection means (or changeover means), and when the operator manually operates the selection switch SW1. The operation signal is input to the CPU 36 (the autofocus control unit 36b and the control unit 36c).
By operating this selection switch SW1, the operator can select one movable range or perform an operation of switching from one movable range to the other movable range. When one of the movable ranges is selected, the autofocus control unit 36b of the CPU 36 performs autofocus control within the one movable range, and when an operation for switching from one movable range to the other movable range is performed. Then, auto focus control is performed within the other movable range.

Note that the selection switch SW1 forming the selection means is constituted by a single switch that generates a signal from OFF to ON and from ON to OFF each time a pressing operation is performed. For example, the first movable range Ka corresponding to the first region Ra is selected when turned OFF, and the second movable range Kb corresponding to the second region Rb is selected when turned ON. When the selection switch SW1 is operated from one selection state, the state is switched to a state for selecting the other.
As described above, in accordance with the operation of the selection switch SW1, the CPU 36 performs control to switch the movable range of the focus lens 26 via the actuator driving unit 37 in response to the operation of the selection switch SW1.

Further, in the present embodiment, when switching from the first movable range Ka to the second movable range Kb is performed by operating the selection switch SW1, the changing unit configured by the CPU 36 in conjunction with this switching. 36d operates the extraction processing unit 33b in the image processing unit 33.
The cutout processing unit 33b, in conjunction with the switching, outputs an image pickup area on the image pickup surface of the CCD 18 that is actually picked up and used for display on the monitor 5 with respect to the output signal of the signal conversion circuit 33a. Change as shown.
The cutout processing unit 33b is linked to the switching from the imaging area of the first imaging area 5a that is normally used for display on the monitor 5 on the imaging surface 18b that forms the entire imaging area of the CCD 18 shown in FIG. Then, the second imaging area 5b is cut out from the first imaging area 5a so that the second imaging area 5b smaller than the first imaging area 5a is set as the imaging area. The cutout processing unit 33b outputs the cutout image signal to the movement / enlargement circuit 33c.
Note that the selection switch SW1 is shaped like a lever, for example, and outputs a switching signal from OFF to ON or ON to OFF by performing an operation of moving the lever to one side.

Assuming that the distance from the center position Po to the farthest position in the case of the first imaging region 5a is Iha, the distance from the center position Po to the farthest position in the case of the second imaging region 5b by the above cutout Is changed from Iha to Ihb.
Of course, in this case, Iha> Ihb. When cutting out, in the default setting state, the second imaging region 5b is cut out so that the center position Po is the same and the shape of the first imaging region 5a is maintained. In the case of FIG. 2, the first imaging region 5a is square, but may be rectangular. Further, an octagonal shape may be formed by cutting out four corners of a square.
The pixels forming the imaging surface 18b are arranged in the horizontal and vertical directions with a pixel pitch P of 1.4 μm, and the number of pixels effective for monitor display is, for example, 700,000 pixel level. doing.

When the first imaging area 5a is switched to the second imaging area 5b in conjunction with the switching, the angle of view (also referred to as a viewing angle) Ava in the case of the first imaging area 5a is changed. The angle of view in the case of the second imaging region 5b is reduced. In the numerical data to be described later, the number of pixels when cut out is shown at a level of 580,000 pixels.
Therefore, in the present embodiment, the adjustment unit 36e formed by the CPU 36 moves the angle-of-view lens 27 that adjusts the angle of view via the actuator driving unit 37 in conjunction with this switching. Then, before and after the switching, the adjustment unit 36e is configured so that the angle of view Ava in the case of imaging in the first imaging area 5a and the angle of view AVb in the case of the second imaging area 5b match within 5%. Adjust (control).
In this way, when a part of the imaging area is cut out from the predetermined imaging area of the CCD 18 and the distance from the center position Po to the farthest position in the predetermined imaging area is changed to be small, the angle of view becomes small. In the present embodiment, the angle of view lens 27 is moved by the adjusting unit 36e so that the angle of view is not reduced.

By adjusting the angle of view lens 27 so that the angle of view does not decrease, the focal length of the objective optical system 17 becomes smaller than before the adjustment, and the depth width can be increased.
Further, in the present embodiment, when switching is performed in this way, the CPU 36 controls the image processing unit 33 so that the image of the imaging region set by switching is displayed on the monitor 5, and before switching. Control to maintain the display size.
The image signal that has passed through the signal conversion circuit 33a and the cut-out processing circuit 33b is input to a movement / enlargement circuit 33c that moves and / or enlarges the image. The movement / enlargement circuit 33c includes a movement circuit that moves an image and an enlargement circuit that enlarges the image. The image signal that has passed through the moving / enlarging circuit 33c is output to the D / A converter 35 through various processing circuits 33d that perform γ correction and the like.

The enlargement circuit in the movement / enlargement circuit 33c is cut out when the display size when generating a normal video signal for displaying an image of the first imaging region 5a on the monitor 5, for example, as shown in FIG. A process of enlarging the second image pickup area 5b so as to have the same display size A is performed.
Further, the moving circuit in the moving / enlarging circuit 33c moves the display position when displaying on the monitor 5 when the selection is made so as to cut out the imaging region with an asymmetric shape without making the center position Po the same. To be able to.
As shown in FIG. 1, for example, the operation unit 8 is provided with a switch SW2 that variably sets an imaging area cutout range for cutting out a part of the first imaging area 5a. The user can variably set the imaging area cutout range by operating the switch SW2. Specifically, in the default setting, for example, as illustrated in FIG. 2, the second imaging area 5 b is the imaging area cutout range.

When a surgeon as a user desires to change the imaging region to be cut out from the setting of the default second imaging region 5b, the imaging region extraction range is increased or decreased via the CPU 36 by operating the switch SW2. To be able to. The surgeon can change and set, for example, the imaging region 5c indicated by the dotted line in FIG. 2 as the second imaging region by operating the switch SW2.
When the imaging area 5c is set to be smaller than the second imaging area 5b, the focal length of the objective optical system 17 is changed by moving the field angle lens 27 and setting the field angle in the same manner as before cutting. 2 and the depth range can be increased. However, the number of pixels is smaller than that in the second imaging region 5b.
Such setting can also be performed by the operator at the time of initial setting before use in the image processing apparatus 4. Even if the switch SW2 is not provided, the switch SW1 has both functions so that the imaging region extraction range can be increased / decreased by the operation of the switch SW1 at the same time when the switch SW1 is operated to switch the movable range. You may make it the structure which combines.

Thus, the surgeon can variably set or select the imaging region cutout range in consideration of the number of pixels and the depth width. The surgeon can prioritize the desired one based on the number of pixels and the depth width, and set the imaging region cutout range.
Information on the set imaging region cutout range is stored in the memory 38 shown in FIG. Further, the amount of movement of the angle-of-view lens 27 described above is changed in accordance with the image-capturing area cut-out range, and information relating the image-capturing area cut-out range and the amount of movement of the angle-of-view lens is stored in the memory 38. It is stored as an up table (LUT) 38a.
The adjusting unit 36e of the CPU 36 refers to the information in the LUT 38a to control the movement amount of the angle-of-view lens 27. The LUT 38a may also store information on the enlargement ratio when the enlargement process is performed by the movement / enlargement circuit 33c. Then, the movement / enlargement circuit 33c refers to the enlargement rate information and performs enlargement image processing in a short time.

FIG. 3 shows a configuration example of the imaging unit 19 including the objective optical system 17 in the distal end portion 11. FIG. 4 is a cross-sectional view of the objective optical system at four representative focal positions when the focus lens 26 and the view angle lens 27 are moved.
As shown in FIG. 4A, the objective optical system 17 includes, in order from the object side, a front group G1 including a focus lens 26 (L3), an aperture stop (simply stop), and a rear group G2.
The front group G1 includes a concave lens L1, a convex lens L2, and a focus lens 26 (L3), and the rear group G2 includes a convex lens L4, and a cemented lens of a convex lens L5 and a concave lens L6. The convex lens L4 is an angle-of-view lens 27 that adjusts the angle of view. Further, optical elements I1 and I2 are disposed behind the rear group G2, and an imaging surface of the CCD 18 is disposed through the mosaic color filter 18a so as to be in contact with the rear surface of the optical element I2.
In FIGS. 4B to 4D, reference numerals are omitted. The same applies to FIGS. 10B to 10D, 12B, and 12C described later.
Numerical data of the objective optical system 17 in the present embodiment is shown below.

Numerical data of the first embodiment Surface number Curvature radius Surface spacing Refractive index Abbe number Object surface ∞ D0
1 ∞ 0.4 1.81991 44.36
2 1.2646 1.18
3 -1.7487 0.52 1.88815 40.76
4 -1.8479 D4
5 2.352 0.815 1.50349 56.42
6 3.0877 D6
7 (Aperture) ∞ 0.07
8 3.4714 1.22 1.48915 70.23
9 -3.1907 D9
10 3.2151 1.2 1.48915 70.23
11 -1.7375 0.3 1.93429 18.9
12 -3.7434 1.4175
13 ∞ 0.79 1.51825 64.14
14 ∞ 0.52 1.50801 60
(Image plane) ∞

1st focal position 2nd focal position 3rd focal position 4th focal position
D0 28 14.7 6.25 5.08
D4 0.25 0.5 1.05 1.45
D6 0.843 0.593 0.643 0.243
D9 0.87 0.87 0.27 0.27
f 1.365 1.349 1.129 1.102
IH 1.284 1.284 1.082 1.082
Angle of view (°) 128.9 129 129.8 131
Depth width (mm) 15.3 to 100 or more 10 to 26 6.16 to 13.7 3.93 to 6.85
Number of pixels 700,000 pixel level 580,000 pixel level Pitch P 1.4μm
The refractive index and the Abbe number are values at the e-line. D0 is the distance from the object plane to the first surface of the objective optical system 17. These are common in other embodiments.

As shown in FIG. 3, the lenses L1 and L2 of the front group G1 are attached to the lens frame 41a, and the movable focus lens L3 (26), the diaphragm, and the movement are moved to the lens frame 41b fitted to the lens frame 41a. A possible angle-of-view lens L4 (27) and cemented lenses L5 and L6 are attached. Optical elements I1 and I2 and the CCD 18 are attached to a lens frame 41c fitted to the rear end side of the lens frame 41b.
The focus lens 26 and the angle-of-view lens 27 are respectively attached to movable lens frames 42a and 42b that are fitted to the inner peripheral surface of the lens frame 41b, and the movable lens frames 42a and 42b are provided on the lens frame 41b. For example, they are integrally connected to the arms 44a and 44b penetrating the moving grooves 43a and 43b. The arms 44a and 44b are connected to rods 46a and 46b protruding from the actuators 45a and 45b.

The actuators 45a and 45b are connected to the actuator drive unit 37 via signal lines 47a and 47b.
The actuators 45a and 45b change the protruding amount of the rods 46a and 46b by the operation of the selection switch SW1 and the drive signal applied from the actuator drive unit 37 under the control of the CPU 36. Then, the focus lens 26 and the angle-of-view lens 27 move along the direction of the optical axis O in accordance with the change in the protruding amount of the rods 46a and 46b.
The signal cable 21 connected to the back surface of the CCD 18 is connected to the CCD driving unit 23 and the CDS circuit 31.

FIG. 5 shows a configuration example of the actuator drive unit 37. In response to the operation of the selection switch SW1, the autofocus control unit 36b of the CPU 36 outputs (or generates) a drive signal to the drive signal output unit 51a configuring the actuator drive unit 37.
This drive signal drives the actuator 45a via the changeover switch 53 connected to each output terminal of the first current limiting circuit 52a and the second current limiting circuit 52b (contacts a and b are respectively connected). Note that the changeover switch 53 switches so that the control unit 36c turns on the contact point a or b in accordance with the operation signal of the selection switch SW1.
When the first area Ra on the far point side is selected by the selection switch SW1, the drive signal drives the actuator 45a via the first current limiting circuit 52a and the contact point a, and the first area on the far point side. The moving range of the focus lens 26 is limited to the first movable range Ka so as to be focused at Ra.

In addition, when the second region Rb on the near point side is selected, the drive signal drives the actuator 45a via the second current limiting circuit 52b and the contact b, and the second region Rb on the near point side is combined. The moving range of the focus lens 26 is limited to the second movable range Kb so as to focus.
The first current limiting circuit 52a and the second current limiting circuit 52b limit the current value of the input drive signal. Specifically, the first current limiting circuit 52a limits the current within the first current value so that the first current limiting circuit 52a can move only within the first movable range Ka close to the object side in the movable range.
On the other hand, the second current limiting circuit 52b limits the current within the second current value so that the second current limiting circuit 52b can move only within the second movable range Kb that is far from the object in the movable range, that is, close to the CCD 18. The drive signal output unit 51a, the first current limit circuit 52a, the second current limit circuit 52b, and the changeover switch 53 form a limit unit 37a.
Note that the amount of protrusion of the actuators 45a and 45b from the reference position of the rods 46a and 46b is regulated by an elastic member such as a spring (not shown), and according to the current value of the drive signal applied to the actuators 45a and 45b, The protrusion amount of the rods 46a and 46b can be adjusted.

In this way, by limiting the movable range of the focus lens 26 to a plurality of, more specifically, two movable ranges Ka and Kb, it is possible to effectively prevent malfunctions when performing automatic focus control. Further, the amount of movement of the focus lens 26 in each of the movable ranges Ka and Kb can be reduced (as compared with a case where the focus lens 26 is not limited), and the speed of autofocus can be improved (in other words, the focus state (focus state) can be set in a short time) ).
The actuator driving unit 37 has a driving signal output unit 51b that outputs a driving signal for driving the angle-of-view lens 27. The driving signal drives the actuator 45b.
This drive signal is controlled by the adjusting unit 36e of the CPU 36 so that it is output only when the selection switch SW1 selects the first movable range Ka to the second movable range Kb or vice versa.

Specifically, when the focus lens 26 performs focusing in the first movable range Ka, the angle-of-view lens 27 is set to an object side position (referred to as a first position) in the movable range, and the focus lens When the lens 26 is focused in the second movable range Kb, the field angle lens 27 is set at a position farther from the object in the movable range, that is, a position closer to the CCD 18 side (second position).
However, when the imaging area cutout range is changed, the amount of movement (of the view angle lens 27) to the second position is adjusted according to the changed imaging area cutout range.
As described above, the focusable range (region) when the moving range of the focus lens 26 is set to the movable range K and is limited to the first movable range Ka is the first region Ra in FIG. The focusable range (region) when limited to the movable range Kb is the second region Rb. The second region Rb is a region on the rear side excluding a part of the region that is very close to the object.

The first region Ra and the second region Rb cover the in-focus region R as a predetermined distance range (object distance range) that needs to be focused and observed in the case of endoscopy. To be able to.
Further, as described above, when the distance range in which the MTF is 10% or more is defined as the depth width, when the first focus position is set as shown in FIG. 6, (as can be understood from the above-described numerical data). When the focus depth is set substantially at a fairly wide object distance of about 100 mm and the second focal position is set, the depth width is about 16 mm. Further, when the third focal position is set, the depth width is approximately 6 mm, and when the fourth focal position is set, the depth width is approximately 5 mm.

When a subject at an arbitrary object distance is focused and observed using the imaging unit 19, the focus lens 26 moves automatically within one of the first region Ra or the second region Rb selected manually. Limited to focus.
In this way, within one restricted region, the autofocus control unit 36b refers to the contrast of the contrast detection unit 36a, moves the focus lens 26 via the actuator driving unit 37, and moves the focus lens 26. In this case, the focus position (focus position) in the focus state where the contrast of the image signal reaches a peak is set.

As shown in FIG. 6, the focal position in the present embodiment is set to the first focal position or the second focal position in the first area Ra, so that a subject with an arbitrary object distance in the first area Ra It can be observed with a wide depth range. In addition, observation can be performed by setting a focus position different from the first focus position and the second focus position.
Further, by setting the third focal position or the fourth focal position in the second region Rb as well, the subject in the second region Rb can be observed with a required depth width. In addition, observation can be performed by setting a focus position different from the third focus position and the fourth focus position.
Further, in the present embodiment, when the focus control is switched so that the subject is focused from the far point side to the near point side, and the imaging region is reduced to observe in detail, the field angle lens 27 is used. Is controlled so that the angle of view is maintained at about 130 ° (see numerical data).
By maintaining the angle of view by the angle-of-view lens 27 in this way, the depth width can be expanded as compared with the case where the angle of view is not corrected.

  The endoscope apparatus 1 according to the present embodiment having such a configuration includes an imaging unit 19 including an objective optical system 17 and a CCD 18 as a solid-state imaging device at the distal end portion 11 of the endoscope 2, and has a predetermined distance. An endoscope apparatus that automatically performs focus control by moving a focus lens in the objective optical system 17 so that a subject at an arbitrary distance within a range is brought into focus. A restriction unit 37a serving as a restriction unit that restricts at least two in-focus areas R for automatic focus control with respect to the subject within a range, and a restricted focus area manually selected with respect to the restriction means Simultaneously with the selection switch SW1 as the selection means to be selected and the selection of the in-focus area by the selection means, a part of the imaging area is cut out from the imaging area on the imaging surface of the solid-state imaging device. And a changing unit 36d as changing means for changing the distance from the center position Po to the farthest position in the image pickup region of the solid-state image pickup device, and movement different from the focus lens 26 in the objective optical system 17 By moving the angle-of-view lens 27 as a lens for use, the angle of view of the image pickup unit 19 is set so that the change in the angle of view is within 5% before and after the change of the image pickup area by the changing means. It is characterized by that.

Next, the operation of this embodiment will be described with reference to FIG.
The endoscope apparatus 1 is set as shown in FIG. 1, and the power is turned on to bring the endoscope apparatus 1 into an operating state. In the first step S1, the CPU 36 sets the focus lens 26 to a state in which autofocus control is performed in the initial setting process.
In addition, as shown in step S2, the CPU 36 sets or determines that the selection switch SW1 is in the OFF setting state as an initial state, and sets the focus lens 26 within the first movable range so that the far point side is the focusing area. Autofocus control is performed as described above.

Further, the CPU 36 sets the angle-of-view lens 27 so as to correspond to the first movable range as shown in step S3. If the field angle lens is set at a position corresponding to the first movable range, this process may not be performed.
In the case of steps S2 and S3, the imaging area of the CCD 18 is the first imaging area 5a in FIG. 2, and the image processing circuit 33 performs image processing corresponding to the first imaging area 5a (step S4). . In this case, the extraction processing circuit 33b does not perform extraction, and the movement / enlargement circuit 33c performs normal image processing without performing movement or enlargement processing. Then, an endoscopic image is displayed on the monitor 5 with a predetermined display size.

As shown in FIG. 6, within the first movable range, a considerably wide (large) depth range can be secured as can be seen from the case of the first focal position and the second focal position as typical focal position states.
For this reason, when the surgeon inserts the endoscope 2 into the body cavity, the imaging unit 19 is set in a state in which the inside of the body cavity can be observed with a wide depth range. That is, screening inspection can be performed smoothly.
When the surgeon wants to observe in detail a site where there is a possibility of a lesion, the operator performs an operation of bringing the tip 11 closer to the site and pressing the selection switch SW1.

As shown in step S5, the CPU 36 monitors whether or not the selection switch SW1 has been operated. If it is determined that the selection switch SW1 has not been operated (step S5 = No), the CPU 36 performs the autofocus control process in step S6. And return to step S5. Step S6 is the same as the processing of step S2, and the processing of steps S3 and S4 is not performed (because it has already been performed).
On the other hand, if it is determined that the selection switch SW1 has been operated (step S5 = Yes), in step S7, the CPU 36 controls the focus lens 26 to move within the second movable range so as to perform autofocus control. .
In conjunction with the processing in step S7, in step S8, the CPU 36 controls to cut out the imaging area from the first imaging area 5a (as the current imaging area) in the CCD 18 to the second imaging area 5b. I do.

In conjunction with the processing in step S7, in step S9, the CPU 36 moves the angle-of-view lens 27 so that the angle of view corresponding to the cut-out imaging area is within 5% of the angle of view before cutting. Control is performed so that the fluctuation range is obtained (that is, the angle of view hardly changes). By this processing, the depth range can be increased.
In conjunction with the processing in step S8, in step S10, the image processing circuit 33 performs image processing for displaying an endoscopic image with the same display size as that before cutting.
Based on the control signal from the CPU 36, the cutout processing unit 33b in the image processing unit 33 extracts only the image signal of the second imaging region 5b and outputs it to the movement / enlargement circuit 33c.

The enlargement circuit in the movement / enlargement circuit 33c enlarges the image so that the image signal of the second image pickup area 5b has the same size as that of the image signal of the first image pickup area 5a. Output.
Accordingly, even when the selection switch SW1 is switched on the display surface of the monitor 5 to observe the near-point part, the endoscope in a state where the display size does not change and the depth width is increased. The image can be observed.
The surgeon can smoothly diagnose a site having a possibility of a lesion by observation on the near point side. When the diagnosis is finished and screening is performed, the operator operates the selection switch SW1.

As shown in step S11, the CPU 36 monitors whether or not the selection switch SW1 has been operated. If it is determined that the selection switch SW1 has not been operated (step S11 = No), the CPU 36 performs auto focus control processing in step S12. Then, the process returns to step S11. Note that the autofocus control in step S12 corresponds to the autofocus control in step S7, and the processing in steps S8, S9, and S10 is not performed (because it has already been performed).
On the other hand, if it is determined that the selection switch SW1 has been operated (step S11 = Yes), in step S13, the CPU 36 determines whether an instruction to end observation (inspection) with the endoscope 2 has been issued, and the processing ends. Is not instructed (step S13 = No), the process returns to step S2, and autofocus control is performed within the first movable range Ka.

On the other hand, when an end instruction is given in step S13 (when step S13 = Yes), the CPU 36 turns off the power of the endoscope apparatus 1 and ends the operation of FIG.
According to this embodiment which operates in this way, when observing on the near point side, it is possible to provide an endoscope apparatus capable of performing observation with an increased depth of field.
In addition, since the focus area that can be set to the in-focus state by the movement of the focus lens 26 is limited to one of a plurality of areas, in the case of an imaging condition in which autofocus is difficult, for example, a contrast change in an endoscopic image Even in an imaging state in which the image is small (small) or an imaging state in which noise is easily affected by the use of an electric knife or the like, it is possible to effectively prevent a malfunction that causes focusing at a significantly different position.
In addition, the movable range of the focus lens 26 is divided into a plurality of, specifically two, and is limited to move within the divided movable range. Can be set to the in-focus state, in other words, the autofocus speed can be improved.

Therefore, according to the endoscope apparatus 1 of the present embodiment, the operator can smoothly perform observation and inspection using the endoscope 2.
In the above description, when the imaging area is cut out by the operation of the switch SW2, the center of the imaging area is cut out in the left-right symmetry and the up-down symmetry, but the operation of cutting out with an asymmetric shape as follows is performed. You may be able to do it.
When an endoscopic image as shown in FIG. 8 is obtained in the focus control state on the far point side, the operator, for example, observes the lower side portion D as a region of interest on the peripheral side in a more visible state. If desired, the cutting or cutting device 50 provided in the operation unit 8 of FIG. 1 is operated, and the cutting range E is designated by the cutting cursors C1 and C2 on the endoscopic image.

When the device 50 is operated, the CPU 36 cuts out an image pickup area corresponding to the cut-out range E in the image pickup area of the CCD 18 from the signal. Then, the CPU 36 controls the imaging region corresponding to the cutout range E so as to perform processing similar to the case where the switch SW2 is operated.
The image processing unit 33 regards the imaging region corresponding to the cutout range E as the second imaging region, and performs image processing so that the monitor 5 displays the same display size as before the cutout.
In this case, the image processing unit 33 forms image processing means for displaying the captured image of the imaging region corresponding to the cutout range E at a position different from the display position of the image before cutout. Since the image is displayed at a position different from the display position of the image before cutting, it can be said that a moving unit that moves to a display position different from the display position of the image before cutting is formed.

Accordingly, in this case, an endoscopic image corresponding to the cutout range E is displayed at a position (and an enlarged size) at which the display position is different from that before the cutout. The surgeon can observe the peripheral region of interest in a state where the region of interest is moved to the center side of the display region on the monitor 5, which makes it easier to observe.
As described above, in this embodiment, in addition to the first to fourth focal positions as shown in FIG. 6, observation can be performed while focusing on a focal position different from these focal positions.
On the other hand, in addition to such focus control, focus control may be performed only at the first to fourth focus positions as shown in FIG.

In this case, as shown in FIG. 6, a focusing zone (MTF) in which the objective optical system 17 is focused at a plurality of positions where the focus lens 26 is set within one focusing area where the movable range is limited. Is divided into a plurality of zones or regions having a depth width of 10% or more.
Specifically, each of the far point side and the near point side is subdivided into two focusing zones. The overlap amount (overlap range) between the far-point side focusing zone on the farthest point side and the focusing zone adjacent to the far-point side focusing zone is set to the near-point side focusing zone on the nearest point side, It is larger than the overlap amount with the focusing zone adjacent to the near point side focusing zone.

Therefore, even when the autofocus control is activated while moving the distal end side of the endoscope 2 particularly on the far point side, the focusing zone changes (moves) in accordance with the movement, but the focusing zone overlaps. Since the amount is large, autofocus control can be performed without blurring the main part being observed even if the focus zone changes (moves).
In the case of FIG. 1 described above, the light source device 3 is a light source device that generates white light, and the imaging unit 19 uses a CCD 18 that includes a mosaic color filter 18a as a color separation filter corresponding to the white light. ing.
On the other hand, it may be configured to emit frame-sequential illumination light as in the light source device 3B shown in FIG. In the light source device 3B, a rotary filter 3e is arranged in the optical path between the lamp 3a and the diaphragm 3c in FIG. The rotary filter 3e is rotated by a motor 3f and supplies frame sequential illumination light to the light guide 14.

In this case, the imaging unit uses a monochrome CCD 18 having no color separation filter. Further, the image processing apparatus in this case is synchronized with the luminance signal Y and the color in the image processing apparatus 4 of FIG. 1 as the signal conversion circuit 33a in the image processing unit 33 from the frame sequential R, G, B image signals. The signal C is converted.
In this case, the definition of the depth width described above is slightly different as follows. The CCD 18 as a solid-state image sensor is composed of a monochrome solid-state image sensor that can generate a luminance signal for each pixel, and the solid-state image sensor has a movable range K that automatically controls focus so as to be in focus. When the pixel pitch in the horizontal direction and the vertical direction is Pmm, when the range in which the MTF of the spatial frequency 1 / (2XP) on the optical axis of the objective optical system 17 is 10% or more is defined as the depth width, A boundary B is set as two movable ranges in a range where the depth width of the focal zone is 10 mm or more and the object distance of the objective optical system 17 is 15 mm or less.

The function and effect in this case are the same as in the case of using the CCD 18 provided with the color separation filter described above.
Further, as shown in FIG. 6, in the first region Ra, information set at the first focal position and the second focal position as a plurality of focal positions (or focal positions) for setting the objective optical system 17 in a focused state. In the second region Rb, information to be set at the third focus position and the fourth focus position is stored in advance as a plurality of focus positions (or focus positions) for setting the objective optical system 17 in a focused state. Anyway.
For example, information such as the drive signal value of the focus lens 26 when the objective optical system 17 is set to the first focus position-fourth focus position is stored in the focus position setting information storage unit 38b in the memory 38 shown in FIG. (Remember.
In addition to the normal autofocus mode (first autofocus mode) described above, a second autofocus mode is prepared in which autofocus is simply performed only at the position of the first focus position-fourth focus position. The surgeon may autofocus using one of the two autofocus modes.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The present embodiment is an embodiment in which an objective optical system 17B that is slightly different from the objective optical system 17 constituting the imaging unit 19 of the first embodiment is used.
Therefore, the endoscope apparatus of the present embodiment has the same configuration as that of the endoscope apparatus 1 in FIG. 1 except that the objective optical system 17B is different from the objective optical system 17.
As shown in FIG. 10 (A), the objective optical system 17B in the present embodiment is different from the objective optical system 17 shown in FIG. 4 (A) in that the convex lens L2 in the front group G1 is changed to a flat optical element L2. ing.
10A to 10D are cross-sectional views at the first focus position, the third focus position, the fourth focus position, and the fifth focus position as typical focus position states.

FIG. 11 shows a characteristic example of the resolving power with respect to the object distance at each focal position.
The numerical data in the present embodiment is shown below.

Number Curvature radius Surface spacing Refractive index Abbe number Object surface D0
1 ∞ 0.4 1.88815 40.76
2 1.1238 0.76
3 ∞ 0.62 1.51965 75
4 ∞ D4
5 1.2768 0.55 1.88815 40.76
6 1.4194 D6
7 (Aperture) ∞ 0.11
8 2.7182 1.09 1.48915 70.23
9 -2.7182 D9
10 4.7991 1.49 1.77621 49.6
11 -2.0966 0.34 1.93429 18.9
12 -8.0131 0.988
13 ∞ 0.95 1.51825 64.14
14 ∞ 0.75 1.61379 50.2
(Image plane) ∞

1st focal position 2nd focal position 3rd focal position 4th focal position 5th focal position
D0 24.3 18.5 12.3 6.63 4.12
D4 0.14 0.17 0.23 0.14 0.3
D6 0.68 0.65 0.59 1.13 0.97
D9 1.17 1.17 1.17 0.72 0.72
f 1.477 1.473 1.464 1.236 1.223
IH 1.346 1.346 1.346 1.126 1.126
Angle of view (°) 135.29 134.85 134.03 134.25 132.19
Depth width (mm) 13.3 to 100 or more 11.2 to 47 8.44 to 21.3 4.84 to 9.95 3.24 to 5.44
Hitch P 2.5μm
In the present embodiment, the object can be observed closer to the object side and in the focused state than in the case of the first embodiment. In addition, the present embodiment has the same effects as the first embodiment.

(Third embodiment)
Next, a third embodiment of the present invention will be described. This embodiment is an embodiment in which an objective optical system 17C slightly different from the objective optical system 17 constituting the imaging unit 19 of the first embodiment is used. Therefore, the endoscope apparatus of the present embodiment has the same configuration as that of the endoscope apparatus 1 of FIG. 1 except that the objective optical system 17C is different from the objective optical system 17.
An objective optical system 17C in the present embodiment is shown in FIG. FIGS. 12A to 12C are cross-sectional views at the first focal position, the second focal position, and the third focal position as typical focal position states in the present embodiment.
In the present embodiment, the entire rear group G2 is used as the field angle lens 27.

FIG. 13 shows a characteristic example of the resolving power with respect to the object distance at the above-described typical focal positions.
The numerical data in the present embodiment is shown below.

Surface number Curvature radius Surface spacing Refractive index Abbe number Object surface ∞ D0
1 ∞ 0.4 1.88815 40.76
2 1.1304 0.7
3 -2.1255 0.6 1.86207 20.4
4 -2.3077 D4
5 10.083 0.63 1.58065 37.1
6 17.2097 D6
7 (Aperture) ∞ 0.05
8 3.7832 0.8 1.60676 47.2
9 -3.1897 0.77
10 6.9093 1.2 1.61885 59.55
11 -1.3 0.35 1.92463 21.2
12 -3.3547 D12
13 ∞ 2 1.51825 64.14
(Image plane) ∞

1st focal position 2nd focal position 3rd focal position
D0 23.4 13.3 7
D4 0.2 0.65 0.65
D6 1.2 0.75 0.4
D12 1.448 1.448 1.798
Depth width (mm) 11-100 or more 7.9-35 5.2-10.1
Angle of view (°) 130.6 130.8 129.6
IH 1.17 1.17 1.33
Hitch P 1.7μm
In the present embodiment, for example, the resolution on the near point side is improved as can be seen from the characteristics in the case where the third focal position is set in FIG. In addition, the present embodiment has substantially the same effect as the first embodiment.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the first to third embodiments described above, the depth width is increased on the near point side so that observation can be performed. On the other hand, in this embodiment, the near point side can be observed with high resolution.
FIG. 14 shows an endoscope apparatus 1D of the present embodiment. This endoscope apparatus 1D employs a CCD 18D having a larger pixel pitch in place of the CCD 18 in the endoscope apparatus 1 of the first embodiment shown in FIG. In contrast to the switching from the far point side to the near point side, the switching of the imaging area in the case of the first embodiment or the like is different as described in FIG.

Further, the endoscope apparatus 1D employs a reduction circuit 33e instead of the movement / enlargement circuit 33c in the image processing apparatus 4 of FIG.
In addition, the changing unit 36d in the present embodiment enlarges the imaging area on the imaging surface 18b of the CCD 18D as the solid-state imaging element simultaneously with the manual selection of the near-point side focusing area by the selection switch SW1 as the selection unit. Thus, the distance from the center position Po to the farthest position in the imaging region is changed.
Further, the adjustment unit 36e moves the view angle lens 27 different from the focus lens 26 in the objective optical system 17D, so that the change in the view angle is within 5% before and after the change of the imaging region by the change unit 36d. Set or adjust as follows. In addition, the endoscope apparatus 1D has the same configuration as the endoscope apparatus 1 of FIG.

FIG. 15 shows an imaging region on the imaging surface 18b of the CCD 18D in this embodiment. In the present embodiment, the imaging area used to actually display as an endoscopic image on the far point side is set to the first imaging area 5d that is narrower than the entire imaging area of the CCD 18D.
Then, when switching to autofocus on the near point side, the changing unit 36d displays (actually displays as an endoscopic image) from the first imaging region 5d to the second imaging region 5e having a larger number of pixels. Change or switch the imaging area (used to do).
In the case of the first imaging area 5d, the distance from the center position Po to the farthest position is changed to Ihd, and in the case of the second imaging area 5e, the distance from the center position Po to the furthest position is changed from Ihd to Ihe. The

Further, in conjunction with this change (switching), the adjustment unit 36e moves the angle-of-view lens 27 as described above so that the change in the angle of view is within 5% before and after the change of the imaging region. Set or adjust.
Note that FIG. 15 shows the second imaging region 5e in the case of default setting, and setting the entire imaging surface 18b as the imaging region as the second imaging region 5e by the operation of the switch SW2. You can also.
Further, the reduction circuit 33e in the image processing unit 33 reduces the image signal of the second imaging area 5e as the enlarged imaging area so as to have the same size as the image size in the first imaging area. Perform image processing and output to the subsequent stage. The monitor 5 displays endoscopic images having the same display size before and after switching.
In this case, since the number of pixels actually used for displaying as an endoscopic image is increased by switching to the near point side, the operator can observe the near point side with higher resolution. . The definition of the depth width is the same as in the first embodiment.

  An endoscope apparatus 1D according to this embodiment includes an imaging unit 19 including an objective optical system 17 and a CCD 18D as a solid-state imaging device at a distal end portion 11 of an endoscope 2, and an arbitrary distance within a predetermined distance range. An endoscope apparatus that automatically performs focus control by moving the focus lens 26 in the objective optical system 17 so as to be in focus with respect to the subject, and with respect to the subject within the predetermined distance range A restriction unit 37a as a restricting unit that restricts at least two in-focus areas for automatic focus control, and a selection switch SW1 as a selecting unit for manually selecting the restricted in-focus area with respect to the restricting unit And at the same time as the selection of the in-focus area by the selection means, the imaging area on the imaging surface of the solid-state imaging element is enlarged, thereby increasing the imaging area of the solid-state imaging element. A change unit 36d as change means for changing the distance from the center position Po to the farthest position, and an angle-of-view lens 27 as a moving lens different from the focus lens 26 in the objective optical system 17. By moving the angle of view, the angle of view of the image pickup unit 19 is set so that the change in the angle of view is within 5% before and after the change of the image pickup area by the changing means.

According to the present embodiment having such a configuration and the above-described operation, it is possible to provide an endoscope apparatus 1D that can perform observation with the affected area on the near point side in a high resolution state.
Since the present embodiment has been described by using the objective optical system 17 of the first embodiment, the same characteristics as those described in the first embodiment are provided with respect to overlapping of the focusing zones.
Note that the present embodiment is not limited to the case where the objective optical system 17 of the first embodiment is used, and the objective optical systems of the second and third embodiments may be adopted.
In addition, an embodiment configured by partially combining the above-described embodiments and modification examples also belongs to the present invention. For example, in the fourth embodiment, a monochrome CCD having no color separation filter may be employed as the CCD 18D.

    DESCRIPTION OF SYMBOLS 1 ... Endoscope apparatus, 2 ... Endoscope, 3 ... Light source apparatus, 4 ... Image processing apparatus, 5 ... Monitor, 7 ... Insertion part, 11 ... Tip part, 17 ... Objective optical system, 18 ... CCD, 19 ... Image pickup unit, 26 ... focus lens, 27 ... view angle lens, 33 ... image processing unit, 33b ... cutout processing circuit, 33c ... moving / enlarging circuit, 36 ... CPU, 36b ... autofocus control unit, 36c ... control unit , 36d ... changing unit, 36e ... adjusting unit, 37 ... actuator driving unit, 37a ... limiting unit, 38 ... memory

Claims (11)

An imaging unit composed of an objective optical system and a solid-state imaging device is provided at the distal end of the endoscope, and the objective optical system is in focus so that a subject at an arbitrary distance within a predetermined distance range is brought into focus. In an endoscope apparatus that automatically controls the focus by moving the focus lens,
Restriction means for restricting at least two in-focus areas for automatic focus control on the subject within the predetermined distance range;
A selection means for manually selecting a restricted focus area with respect to the restriction means;
Simultaneously with the selection of the focusing area by the selection means, a part of the imaging area is cut out from the imaging area on the imaging surface of the solid-state imaging device, and the distance from the center position to the farthest position in the imaging area of the solid-state imaging element is determined. Change means to change;
With
By moving a moving lens that is different from the focus lens in the objective optical system, the angle of view of the imaging unit is set to be within 5% before and after the imaging unit is changed by the changing unit. An endoscope apparatus characterized by:   The endoscope apparatus according to claim 1, further comprising an image processing unit that performs image processing so that a display size does not change before and after the imaging region is cut out.   Within the restricted one focusing area, the focusing zone where the objective optical system is focused is subdivided into a plurality of focusing areas, and the focusing in each focusing area is shifted from the closest focusing zone to the far-point focusing zone. The endoscope apparatus according to claim 2, wherein the overlapping of the focal zones is large. The solid-state imaging device is composed of a solid-state imaging device for color imaging in which a color separation filter is arranged for each pixel,
The limiting means has a spatial frequency on the optical axis of the objective optical system when the horizontal pixel pitch of the solid-state imaging device is Pmm with respect to a movable range in which focus control is automatically performed so that the in-focus state is achieved. When the depth width is a range where the 1 / (3XP) MTF is 10% or more, the depth width of one focusing zone is 5 mm or more, and the object distance of the objective optical system is 15 mm or less. The endoscope apparatus according to claim 3, wherein a boundary of at least one in-focus area is set in a range.   The solid-state image sensor is composed of a solid-state image sensor that generates a luminance signal for each pixel, and the restricting unit is arranged horizontally with respect to a movable range in which focus control is automatically performed so that the in-focus state is achieved. When the pixel pitch in the direction is Pmm, the depth width of one in-focus zone when the range where the MTF of the spatial frequency 1 / (2XP) on the optical axis of the objective optical system is 10% or more is defined as the depth width The endoscope apparatus according to claim 3, wherein at least one in-focus region boundary is set in a range where the distance between the objective optical system and the objective optical system is 15 mm or less.   In order from the object side, it is composed of a front group with negative refractive power, an aperture stop, and a rear group with positive refractive power, the front group is composed of a concave lens and a convex lens, and the rear group is composed of a convex lens and a cemented lens. 6. The endoscope apparatus according to claim 1, wherein the moving lens for adjusting the angle of view is the convex lens in the rear group. An imaging unit composed of an objective optical system and a solid-state imaging device is provided at the distal end of the endoscope, and the objective optical system is in focus so that a subject at an arbitrary distance within a predetermined distance range is brought into focus. In an endoscope apparatus that automatically controls the focus by moving the focus lens,
Restriction means for restricting at least two in-focus areas for automatic focus control on the subject within the predetermined distance range;
A selection means for manually selecting a restricted focus area with respect to the restriction means;
Change to change the distance from the center position to the farthest position in the imaging area of the solid-state image sensor by enlarging the imaging area on the imaging surface of the solid-state image sensor simultaneously with the selection of the focusing area by the selection means Means,
With
By moving a moving lens that is different from the focus lens in the objective optical system, the angle of view of the imaging unit is set to be within 5% before and after the imaging unit is changed by the changing unit. An endoscope apparatus characterized by:   Within the restricted one focusing area, the focusing zone in which the objective optical system is focused is subdivided into a plurality of focusing areas, and the focusing in each focusing area is shifted from the closest focusing zone to the far-point focusing zone. The endoscope apparatus according to claim 7, wherein the overlapping of the focal zones increases. The solid-state imaging device is composed of a solid-state imaging device for color imaging in which a color separation filter is arranged for each pixel,
The limiting means has a spatial frequency of 1 on the optical axis of the objective optical system when the horizontal pixel pitch of the solid-state imaging device is Pmm with respect to a movable range in which focus control is automatically performed so that the in-focus state is achieved. / When the range in which the MTF of (3XP) is 10% or more is defined as the depth width, the depth width of one focusing zone is 10 mm or more, and the object distance of the objective optical system is 15 mm or less. The endoscope apparatus according to claim 8, wherein a boundary of at least one focusing area is set inside. The solid-state image sensor is composed of a solid-state image sensor that generates a luminance signal for each pixel,
The limiting means has a spatial frequency 1 / on the optical axis of the objective optical system when the horizontal pixel pitch of the solid-state imaging device is Pmm with respect to a movable range in which focus control is automatically performed so that the in-focus state is achieved. When the range in which the MTF of (2XP) is 10% or more is defined as the depth width, the depth width of one focusing zone is 10 mm or more, and the object distance of the objective optical system is 15 mm or less. The endoscope apparatus according to claim 8, wherein a boundary of at least one focusing area is set.   In order from the object side, it is composed of a front group with negative refractive power, an aperture stop, and a rear group with positive refractive power, the front group is composed of a concave lens and a convex lens, and the rear group is composed of a convex lens and a cemented lens. The endoscope apparatus according to claim 8, wherein the moving lens that adjusts the angle of view is the convex lens in the rear group.

Images