JP4574913B2 - Electronic endoscope apparatus having a zooming function - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope apparatus having a zooming function, in particular, an electronic endoscope capable of observing an optically magnified image by a movable lens and forming an electronically magnified image by signal processing. The present invention relates to a zooming operation control of the apparatus.
[0002]
[Prior art]
In recent years, in electronic endoscope devices and the like, a movable lens for zooming is disposed in the objective lens system at the distal end portion of the scope, and this movable lens is driven by an actuator or the like to optically enlarge the observed object image. Has been done. This optically enlarged image is picked up by an image pickup device such as a CCD (Charge Coupled Device), and an output image from the CCD is subjected to various image processing by a processor device, whereby an enlarged image of the object to be observed is displayed on the monitor. Is displayed. In such an optical zoom mechanism, the observation image can be enlarged up to about 70 to 100 times.
[0003]
On the other hand, the image obtained by the CCD has been conventionally electronically enlarged by pixel interpolation processing of an electronic zoom circuit, etc., and according to this, the optically enlarged image is further enlarged. Can be displayed on a monitor and observed.
[0004]
In such a magnification function of an electronic endoscope apparatus, an optically magnified image with an optical magnification and an electronic magnification switch can be electronically magnified or The optical zooming and the electronic zooming are associated with each other by using a common zooming switch of the mirror operation unit. When using this common zoom switch, after moving the movable lens to the zooming end (Near end) by optical zooming, it automatically shifts to electronic zooming for further zooming by signal processing. An image is formed, and according to this, a specific site such as an affected part can be observed quickly and at a good magnification.
[0005]
[Problems to be solved by the invention]
However, in the optical zoom mechanism using the movable lens in the conventional electronic endoscope apparatus, the depth of field becomes shallower as the enlargement rate increases. In some cases, the entire image could not be displayed well. This will be described with reference to FIGS.
[0006]
6A shows a state in which the object 2 is imaged on the CCD imaging surface 3 when the movable lens 1 is at the base end (Far end), and FIG. The imaging state when moving to the (Near side) is shown. In FIG. 6, since the movable lens 1 is set at the position of the distance 0, in the enlarged view (B), the imaging surface 3 is drawn shifted to the rear side, but actually the movable lens 1 is moved to the front side. Moving. When the optical expansion is not performed as shown in FIG. 6A, the focus is achieved at a distance of 8 to 100 mm, for example, and the depth of field is 92 mm, but when the optical expansion is performed as shown in FIG. 6B. Is in focus at a distance of 4 to 20 mm, and the depth of field is 16 mm.
FIG. 7 is an explanatory diagram of the depth of field. When the focal length of the lens 4 is f, the F number is F _N , the allowable circle of confusion is δ, and the object distance to be observed is L, the rear field is shown. The depth of field L _r and the front depth of field L _f are as follows.
L _r = (δ · F _N · L ² ) / (f ² −δ · F _N · L) (1)
L _f = (δ · F _N · L ² ) / (f ² + δ · F _N · L) (2)
Then, the depth of field of the lens 4 is a value obtained by adding the backward depth of field L _r and the front depth of field L _f, the L r ₊ L _f. Incidentally, the depth of focus is 2δ · _{F N.}
[0008]
The depth of field described with reference to FIG. 6 is also the value of L _r + L _f , and the focusing range is 92 mm in FIG. 6A and 16 mm in FIG. 6B. In the configuration of the variable magnification objective optical system used in the mirror, the depth of field becomes shallower as it expands.
Therefore, when observing an object to be observed with unevenness, the depth of field becomes shallow (short), and blur occurs in part in the depth direction. Then, if the object to be observed captured with a shallow depth of field is electronically enlarged, the blur in the depth direction will also be enlarged, and the entire object will be displayed with good image quality. However, there is a problem that it cannot be observed.
[0009]
The present invention has been made in view of the above problems, and its object is to switch only the depth of field to a good value during observation of a magnified image to eliminate blur in the depth direction, thereby smoothing image observation. It is an object of the present invention to provide an electronic endoscope apparatus having a zooming function that can be performed at the same time.
[0010]
In order to achieve the above object, an invention according to claim 1 is obtained via an objective optical system that optically zooms an observation image by a zooming lens based on an operation of a zooming switch, and an imaging element. In an electronic endoscope apparatus including an electronic magnification circuit that electronically varies an image obtained through signal processing, the depth of field is arbitrarily set in the optical magnification , provided separately from the magnification switch. A depth operation means for changing the value to the value of the image, and the objective optical system is driven and controlled so that the depth of field selected by the operation of the depth operation means is maintained, and the image magnification immediately before the operation is maintained. And a control circuit for controlling an electronic scaling operation of the electronic scaling circuit.
According to a second aspect of the present invention, the control circuit sets a maximum magnification allowed for electronic enlargement with respect to the depth of field selected by the operation of the depth operation means.
[0011]
Since the depth of field is specified by the lens position of the movable lens for image enlargement, it can be grasped even by the magnification of the optical enlargement. According to the above configuration, the magnification is enlarged to 72 times, for example, by optical magnification. Assuming that a predetermined depth of field (for example, a depth corresponding to 60 times) is selected by the depth operation means in this state, 1.2 times is set for electronic scaling. As a result, an enlarged image of the same magnification as that immediately before the depth operation can be displayed, and if the depth of field value is, for example, 7 mm at 72 times and 12 mm at 60 times, the in-focus range is set in the depth direction. It is possible to observe a magnified image that is 5 mm wide and is in focus within a desired range.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration of an electronic endoscope apparatus according to the embodiment. In FIG. 1, an objective optical system 11 having a zoom lens is provided at the distal end portion of an electronic scope (electronic endoscope) 10, and an imaging surface is made to coincide with an imaging position of the objective optical system 11. Thus, the CCD 12 is arranged. The objective optical system 11 has a configuration as shown in FIG. 2, for example.
[0013]
As shown in FIG. 2, the objective optical system 11 includes a fixed first lens (group) L ₁ , a movable second lens L ₂ that mainly performs a magnification function, and other functions (for example, a field curvature characteristic). a third lens (group) L ₃ of the movable fulfilling change), the imaging surface 12S of CCD12 through the prism 14 to the rear of the third lens L ₃ are arranged. According to such an objective optical system 11, both the second lens L ₂ and the third lens L ₃ are moved relative to each other in the optical axis direction to change the image and to change, for example, the field curvature characteristic. Can be changed. In this example, by moving to the front side of the second lens L ₂ together with the third lens L _3, the image expansion is performed.
[0014]
In Figure 1, the are second lens L ₂ and the third actuator and the position detector 15 to drive the lens L ₃ of the objective optical system 11 is provided as the actuator, and the linear actuator, linear transmission in the motor It is possible to use a configuration in which the members are driven to rotate, the rotational motion is converted into linear motion, and the lenses L ₂ and L ₃ are moved. The actuator and position detector 15 is provided with a driver 16 for grasping the lens position and executing a zooming operation.
[0015]
Further, a zooming switch (two-operation switch) 17 for operating the near (enlargement) direction and the far (reduction) direction in both optical enlargement and electronic enlargement is disposed in the operation unit of the electronic scope 10. Is done. That is, in the variable power switch 17 (depth of field priority mode), is performed first optical magnification, after moving the second lens L ₂ to the enlarged end (Near end) automatically electronically enlarged It is supposed to move to.
[0016]
On the other hand, in the processor unit 20, the actuator driver 16 is controlled, and an operation signal of the zoom switch 17 is input to perform optical zooming, electronic zooming, and other various controls. As will be described later, a microcomputer 21 that performs control for forming an equal-magnification image of a depth of field selected based on the operation of the variable depth equal-magnification observation switch (34), and for reading an imaging signal to the CCD 12 A timing generator (TG) 22 that supplies a control signal is provided.
[0017]
As a video signal processing system, a CDS (correlated double sampling) / AGC (automatic gain control) circuit 24, an A / D converter 25, a DSP that performs various digital processes such as white balance, gamma correction, and contour correction. (Digital Signal Processor) 26, an electronic zoom IC circuit 27 as an electronic zoom circuit, a D / A converter 28, and an encoder (ENC) 29 that performs output processing in accordance with the monitor format are arranged. It is supplied to the monitor 30. The electronic zoom IC circuit 27 can store the video signal obtained by the DSP 26 in a memory and form an enlarged image by a process of interpolating horizontal and vertical pixels.
[0018]
Further, the processor device 20 obtains the depth of field and the value of the magnification ratio, data for forming other characters, or the position of the movable lens L ₂ (or L ₃ ) corresponding to the depth of field. A ROM (read only memory) 31 for storing calculation data and the like and a character generator 32 for generating various characters are provided. A character image such as a depth of field and an enlargement ratio is formed.
[0019]
Further, for example, three (this number is arbitrary) variable depth equal magnification observation switches 34 are provided on the operation panel 33 of the processor device 20, and the variable depth equal magnification observation switches 34 are provided. Three depths of field can be selected. In this example, the value of the depth of field that can be selected by the variable depth equal magnification observation switch 34 is set to an arbitrary value by displaying a function setting screen on the monitor 30 in advance and inputting numerical values using various keys. can do. The variable depth equal magnification observation switch 34 may be disposed on the electronic scope 10 side.
[0020]
Then, in the microcomputer 21 position of the second lens L ₂ corresponding to the depth of field is set by the variable depth equal-magnification observation switches 34 are stored in the internal storage unit (RAM, etc.). In this example, as shown in FIG. 3, if 12 mm, 24 mm, and 36 mm are set as values of the depth of field, for example, the lens positions a ₁ , a ₂ , a at which these depths of field are set. ₃ is stored.
[0021]
In addition, when a certain depth of field signal is input to the microcomputer 21 by operating the variable depth equal magnification observation switch 34 during an arbitrary enlargement operation, the lens position (a ₁ ,) corresponding to the depth of field signal is input. The magnification ratio Ce of the electronic magnification change is calculated from a ₂ , a ₃ ) and the current position p of the second lens L ₂ . For example, if the magnification ratio (Ca) of the lens position a ₁ (focal length f ₁ ) is 60 times and the magnification ratio (Cp) of the lens position p ₁ (focal length f ₂ ) currently driven is 72 times, Ce = Cp / Ca = 72/60 = 1.2 is obtained. Then, the microcomputer 21 controls the electronic zoom IC circuit 27 so as to perform the electronic enlargement with the electronic enlargement ratio Ce, thereby forming an image having the same magnification as that immediately before the operation of the switch 34.
[0022]
The embodiment is configured as described above, and the operation thereof will be described next. In the apparatus, when the magnification switch 17 of the operation unit of the electronic scope 10 is operated, the second lens L ₂ (and the third lens L ₃ ) is moved and controlled by the driver 16 and the actuator 15, and focused in the Near direction. An enlarged image is obtained from the basic image, and a reduced image returning to the basic image is obtained by focusing in the Far direction, and these images are picked up by the CCD 12.
[0023]
That is, when the zoom switch 17 is not operated, the movable second lens L ₂ (and L ₃ ) is disposed at the Far end, and the object to be observed 34a at a long distance is displayed on the imaging surface as shown in FIG. imaged as an image Ka to 12S, the enlargement operation is performed by zooming switch 17, the second lens L ₂ of the movable as shown in FIG. 2 (B) is moved to the front side, at the maximum expansion (Near end) Then, the observation object 34b at a short distance forms an image Kb.
[0024]
The signal output from the CCD 12 is read by the read signal of the timing generator 22, subjected to correlated double sampling and amplification processing by the CDS / AGC circuit 24, and then subjected to various processing by the DSP 26 as a digital signal. The The video signal thus formed is output to the monitor 30 via the electronic zoom IC circuit 27 and the encoder 29. When optical zooming is performed as described above, the object to be observed is optically enlarged on the monitor 30. A body image is displayed. When the enlargement operation of the zoom switch 17 is further performed, the electronic enlargement process is performed by the electronic zoom IC circuit 27 with the lens position (Near end) in FIG. A further enlarged image of the observed object is displayed on the monitor 30.
[0025]
On the other hand, in this apparatus, the depth of field can be selected and set to an arbitrary value by the variable depth equal magnification observation switch 34 described above, and the setting of the depth of field for that purpose is performed by the operation of FIG. That is, in step 101 of FIG. 4, on the function setting mode screen displayed on the monitor 30, for example, three depth of field values (12 mm, 24 mm, and 36 mm in FIG. When input, in step 102, the positions a ₁ , a ₂ , a _{3 of} the movable lens L ₂ corresponding to the subject depth are calculated, and these lens positions are selected and set in the variable depth equal magnification observation switch 34 in step 103. And stored in a memory or the like. In this example, in order to prevent blurring of the image due to electronic enlargement, an allowable maximum magnification b (for example, 2 to 3 times) of electronic enlargement is also input, and this magnification value is also stored and set. The
[0026]
FIG. 5 shows an overall operation (mainly related to the microcomputer 21) performed based on the operation of the variable depth equal magnification observation switch 34. In step 201, the variable depth equal magnification observation switch 34 is shown. There Once turned on, the position p of the second lens L ₂ of the current step 202 is read, at the next step 203, the lens position of the depth of field is selected the movable lens L ₂ from the current position Is driven via the driver 16. For example, if the selected depth of field is 12 mm, it is moved to the lens position a ₁ as shown in FIG.
[0027]
In step 204, the selected lens position a ₁ and electronic magnification of the magnification Ce from the position p of the current second lens L ₂ of the depth of field is calculated, the electronic expansion control of the enlargement ratio Ce Is done. That is, as shown in FIG. 3, the lens position corresponding to a depth of field of 12 mm is a ₁ (optical magnification factor Ca = 60 times), and the current position of the second lens L ₂ is p ₁ (covered object). Assuming that the depth of field is 7 mm and the optical magnification is Cp = 72, the magnification ratio Ce of the electronic magnification is Cp / Ca = 72/60 = 1.2 as described above. Accordingly, the electronic zoom IC circuit 27 in FIG. 1 performs an electronic enlargement process of 1.2 times. As a result, an enlarged image of 72 times that is the same magnification as that immediately before the operation is formed, and the depth of field is increased. An enlarged image converted from 7 mm to 12 mm is displayed on the monitor 30.
[0028]
In the next step 205, focusing is performed by the endoscope user as necessary. In other words, it means that focus range if changing the depth of field by moving the aforementioned movable lens L ₁ is widened, the focus on the desired range in the depth direction by finely adjusting the position of the endoscope tip May need to work together. In step 206, a still image capturing operation is performed, and when a desired enlarged image is obtained, it is currently obtained based on the operation of a still image recording switch or the like provided in the electronic scope 10. A still image is formed from the enlarged moving image, and this is recorded on a recording device such as a hard copy.
[0029]
Next, when the variable depth equal magnification observation switch 34 is turned off in step 207, in step 208, processing for returning to the original state before the switch operation is performed. That is, the second lens L ₂ is returned to the position p ₁ and the electronic magnification ratio is set to 1 (the electronic magnification processing by the electronic zoom IC circuit 27 is stopped). Incidentally, just before the variable depth equal-magnification observation switch 34 is operated, the second lens L ₂ is in the Near end sometimes electronic enlargement is already running, this case, the electronic expansion just before the switch operation Return to rate.
[0030]
In this way, by operating the variable depth equal-magnification observation switch 34 during the enlargement operation, in this example, not only 12 mm but also any selected depth of field of 24 mm and 36 mm can be used. An image that is the same size as the pre-operation image can be obtained. In this example, the maximum value of electronic enlargement is set to a predetermined value (2, 3 times), and even if the calculated value Ce becomes a value larger than this, it is not enlarged beyond the predetermined value. This prevents blurring of the image due to electronic enlargement.
[0031]
In this example, the zoom switch 14 operates by associating optical zoom with electronic zoom, and the depth of field value for switching from optical zoom to electronic zoom is an arbitrary value. The depth-of-field priority mode can be set. That is, normally, switching to electronic scaling is performed with the near-field depth value (d) shown in FIG. 3, but the depth of field for this switching can be set to an arbitrary value deeper than d. The depth of field priority mode can be executed. For example, if the depth of field priority mode switching depth of field is set to 10 mm as shown in FIG. 3, when the second lens L ₂ is moved to the position a ₀ , Electronic scaling is switched.
[0032]
In the above-described embodiment, three depth-of-field values can be set as the variable depth equal magnification observation switch 34. However, a variable depth depth switch or the like is provided together with one variable depth equal magnification observation switch 34, variable depth, etc. The depth of field operated by the double observation switch 34 may be freely changed by a variable switch. Further, when the depth of field immediately before the operation of the variable depth equal magnification observation switch 34 is deeper than the value set by the switch 34, the operation of the switch 34 can be invalidated. Further, when the variable depth equal magnification observation switch 34 is operated, the subject depth (lens position) may be controlled to be shifted in the direction of increasing by a predetermined amount regardless of the magnification. .
[0033]
【The invention's effect】
As described above , according to the present invention, the depth operation means for changing the depth of field in the optical magnification to an arbitrary value is provided separately from the above-described magnification switch. The objective optical system is driven and controlled to achieve the selected depth of field, and the electronic magnification operation of the electronic magnification circuit is controlled so as to maintain the image magnification immediately before the operation. During observation, only the depth of field can be switched to a good value to eliminate the blur in the depth direction, and the image observation in the electronic endoscope apparatus having a zooming function can be made smooth. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an electronic endoscope apparatus having a scaling function according to an embodiment of the present invention.
FIGS. 2A and 2B show a configuration and an imaging state of an objective optical system according to an embodiment, in which FIG. A shows a Far end, and FIG. B shows a Near end.
FIG. 3 is an explanatory diagram showing a depth of field and a lens position set by the objective optical system according to the embodiment.
FIG. 4 is a flowchart showing a depth-of-field setting operation of the variable depth equal magnification observation switch in the embodiment.
FIG. 5 is a flowchart showing an overall operation based on a variable depth equal magnification observation switch in the embodiment.
FIG. 6 is an explanatory diagram showing a depth of field that is changed by an optical zoom mechanism provided in the endoscope.
FIG. 7 is an explanatory diagram of a depth of field of a lens.
[Explanation of symbols]
10 ... electronic scope, 11 ... objective optical system,
12 ... CCD,
15 ... Actuator and position detector,
17 ... zoom switch, 21 ... microcomputer,
27 ... Electronic zoom IC circuit, 31 ... ROM,
32 ... Character generator,
33 ... operation panel,
34… Variable depth equal magnification observation switch,
L ₂ ... second lens (movable lens),
L ₃ ... Third lens (movable lens).

Claims (2)

An objective optical system that optically zooms the observation image with a zooming lens based on the operation of the zooming switch, and electronic zooming that electronically zooms the image obtained through the image sensor using signal processing In an electronic endoscope apparatus comprising a circuit,
A depth operation means provided separately from the zoom switch, for changing the depth of field in the optical zoom to an arbitrary value;
The objective optical system is driven and controlled to achieve the depth of field selected by the operation of the depth operation means, and the electronic magnification operation of the electronic magnification circuit is performed so as to maintain the image magnification immediately before the operation. An electronic endoscope apparatus having a zooming function, characterized by comprising a control circuit for controlling. 2. The electronic endoscope apparatus according to claim 1, wherein the control circuit sets a maximum magnification allowed for electronic enlargement with respect to a depth of field selected by operation of the depth operation means.

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