JPH11281899A - Endoscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove the influence of the weaving pattern of an image guide fiber bundle at low cost. SOLUTION: The endoscope device is provided with a spatial f-characteristic varying circuit 24 and an encoder 25 behind a knee-and-γ correcting circuit in CCU(camera control unit) 5 and after a spatial frequency characteristic varying process is performed by the spatial f-characteristic varying circuit 24, conversion to a standard Tv signal is performed by the encoder 25; and impedance matching is performed by a 75 Ω driver 26 and the resulting signal outputted to a TV monitor. Further, a CPU 31 outputs coefficient data to the spatial f-characteristic varying circuit 24 according to the indication signal from a switch SW32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope apparatus, and more particularly to an endoscope apparatus having a feature in a spatial frequency processing section for an image.

[0002]

2. Description of the Related Art Conventionally, an optical endoscope capable of detachably connecting a TV camera which transmits a subject image to an eyepiece by an image guide, photoelectrically converts the image by an image pickup device and outputs an electric signal to the eyepiece. Various imaging devices used in the field of have been proposed.

However, in the above-described image pickup apparatus, a stitch pattern caused by each bundle of image guide fibers of the image guide hinders observation on a monitor.

Therefore, since the stitches formed by the image guide fiber bundles are periodically arranged, the effect of the stitches of each image guide fiber bundle is conventionally removed by a low-pass filter for the spatial frequency.

[0005]

However, in order to eliminate the influence of the stitch pattern caused by the image guide fiber bundle, it is conventionally necessary to construct the above-mentioned low-pass filter exclusively for the image guide fiber bundle. There is a problem that can not be.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an imaging apparatus capable of removing the influence of a stitch pattern caused by an image guide fiber bundle at low cost.

[0007]

An endoscope apparatus according to the present invention comprises:
A fiber endoscope having an image guide fiber bundle for transmitting an endoscope image to an eyepiece in an insertion portion inserted into a lumen; and an imaging device detachably attached to the eyepiece to capture the endoscope image. In an endoscope apparatus comprising means and a signal processing means for performing signal processing on a video signal from the imaging means, the signal processing means is provided with a spatial filter that makes a spatial frequency characteristic variable.

In the endoscope apparatus according to the present invention, the spatial filter provided in the signal processing means makes the spatial frequency characteristic variable, so that the effect of the stitch pattern caused by the image guide fiber bundle can be removed at low cost. Make it possible.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 6 relate to an embodiment of the present invention. FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus, FIG. 2 is a configuration diagram showing a configuration of a CCU in FIG. 1, and FIG. The space f in FIG.
FIG. 4 is a configuration diagram showing the configuration of the first delay circuit in FIG. 3, and FIG. 5 is a configuration diagram showing the configuration of the image guide fiber bundle inserted into the insertion portion of the scope in FIG. FIG. 6 is a diagram showing an example of the frequency characteristic of the spatial frequency characteristic variable circuit of FIG.

(Structure) As shown in FIG. 1, an endoscope apparatus 1 according to the present embodiment has a camera head 2 having built-in image pickup means.
And a scope 3 to which the camera head 2 is detachably connected, and a light source device 4 for supplying illumination light to the scope 3
A camera control unit (hereinafter abbreviated as CCU) 5 as a processor main body for performing signal processing on image pickup means provided in the camera head 2;
And a TV monitor 6 for displaying a standard video signal processed by U5.

The scope 3 is an optical endoscope provided with an insertion section 7 for inserting an image guide fiber bundle (not shown) which is elongated and flexible and transmits an endoscope image. By connecting the camera head 2 to the eyepiece of the operation unit 8 provided at the base end of the insertion unit 7 via the adapter 2a in a detachable manner, an image guide fiber bundle (not shown) is provided.
Thus, the endoscope image transmitted to the eyepiece of the operation unit 8 can be captured by the camera head 2.

A light guide cable 9 extends from the operation unit 8 of the scope 3. By connecting the tip of the light guide cable 9 to the light source device 4, the illumination light supplied from the light source device 4 A light guide (not shown) inserted through the guide cable 9 and the insertion section 7 irradiates a subject (not shown) from the distal end of the scope 3.

That is, when the endoscope apparatus 1 is used, the light guide cable 9 of the scope 3 is attached to the light source apparatus 4 so that, although not shown, the illumination light of the lamp in the light source apparatus 4 passes through the stop. The light is condensed by the lens and is incident on the end face of the opposing light guide. This illuminating light is transmitted to the scope 3 by the light guide, passes through the scope 3 and is emitted forward from the distal end of the scope 3 to illuminate an object such as a lumen.

The reflected light of the subject illuminated by the illuminating light is imaged by the scope 3, and the subject image is picked up by the image pickup means in the camera head 2 through the scope 3.

On the other hand, in the camera head 2, a CCD 11 as an image pickup means is disposed on the focal plane of the image pickup lens (see FIG. 2), and a subject image is formed on the image pickup plane of the CCD 11 and photoelectrically converted. . The CCD 11 is connected to the CCU 5 via a camera cable 12 extending from the camera head 2 in which a CCD drive signal transmission line and a CCD output signal transmission line are inserted, and an output signal of the CCD 11 is sent to the CCU 5. Various signal processing is performed. The video signal output from the CCU 5 is sent to the TV monitor 6, and an observation image of the subject is displayed on the TV monitor 6.

As shown in FIG. 2, the CCU 5 includes a CC
A CCD driver 13 for driving and controlling the D11 is provided, and a CCD driving signal is transmitted from the CCD driver 13 via a CCD driving signal transmission line in the camera cable 12.
Signal charge supplied to the CCD 11 and stored in the CCD 11
Read as a CD output signal.

The CCD read from the CCD 11
The output signal is amplified by the preamplifier 14 and transmitted through the CCD output signal transmission line in the camera cable 12 to the CCU.
5 and input to the pre-processing circuit 15 in the CCU 5.

An A / D conversion circuit 16, an isolation circuit (hereinafter abbreviated as IL) 17 and a Y / C separation circuit 18 are provided at the subsequent stage of the pre-processing circuit 15. CCD output signal is CD
After performing preprocessing such as S (correlated double sampling) and S / H (sample hold), it is input to the A / D conversion circuit 16 and converted into a digital signal. The signal is electrically isolated by L17 and input to the Y / C separation circuit 18.

A color difference LPF is provided at a stage subsequent to the Y / C separation circuit 18.
(Low-pass filter) 19, line-sequential synchronization circuit 20
And a color separation circuit 21 composed of an RGB matrix is provided. The digital signal input to the Y / C separation circuit 18 is separated into a luminance signal Y and a chroma signal C. After being removed, the digital signals are line-sequentialized by a line-sequential synchronization circuit 20, and three digital signals of Y, CR, and CB are input to a color separation circuit 21 and converted into RGB digital signals by the color separation circuit 21. .

An AGC & painting circuit 22 and a knee & γ correction circuit 23 are provided at a subsequent stage of the color separation circuit 21. Is performed, the knee process and the γ correction process are performed by the knee & γ correction circuit 23.

A spatial frequency characteristic variable circuit (hereinafter abbreviated as a space f characteristic variable circuit) 24 and an encoder 25 are provided downstream of the knee & γ correction circuit 23.
After the spatial frequency characteristic variable processing described later is performed by the special variable circuit 24, the signal is converted into a standard TV signal, for example, NTSC by the encoder 25, and the 75Ω driver 26
Thus, the impedance is matched and output to the TV monitor 6.

The CCU 5 is provided with a reference signal generation circuit (hereinafter abbreviated as SSG) 27,
The driver 13 is driven based on the reference clock signal from the SSG 27, and A timing signal generation circuit (hereinafter abbreviated as TG) 2 based on a reference clock signal generated from SSG 27 electrically insulated via L28;
Numeral 9 generates various timing signals to the various circuits.

Further, the CPU 31 is provided in the CCU 5, and based on an instruction signal from a switch (hereinafter abbreviated as SW) 32, the CPU 31 changes the space f characteristic variable circuit 24.
Output coefficient data.

It should be noted that I. L17, L28 are endoscope devices 1
Is a medical device, so the scope 3 side and CCU5
It is provided to ensure safety by electrical insulation from the side.

As shown in FIG. 3, the spatial frequency characteristic variable circuit 24 includes a first multiplier 41 for multiplying the RGB digital signal passed through the knee & γ correction circuit 23 by a coefficient signal K11 from the CPU 31, and a knee & γ correction circuit. The four delay elements 55, 56, 57, 58 shown in FIG. 4 for delaying the clock signal (hereinafter abbreviated as CK) from the TG 29 by 1CK to 4CK with respect to the RGB digital signal via the circuit 23.
And a first delay circuit 42 comprising a
For the RGB digital signal from the delay circuit 42 of FIG.
A second multiplier 43 for multiplying the coefficient signal K12 from U31
A second delay circuit 44 configured similarly to the first delay circuit 42 for delaying the RGB digital signal via the first delay circuit 42 by 1CK to 4CK of the CK from the TG 29; A third multiplier 45, a first multiplier 41, and a second multiplier 4 for multiplying the RGB digital signal from the delay circuit 44 by the coefficient signal K13 from the CPU 31.
A first delay group circuit 46 including an adder 47 for adding the outputs of the third and third multipliers 45 is provided.

Further, the space f characteristic variable circuit 24 has a knee
A second delay group circuit 49 configured similarly to the first delay group circuit 46 that produces the same effect on the output of the first line memory 48 that delays the RGB digital signal by one line via the & γ correction circuit 23. And the first line memory 48
Of the second line memory 50 for delaying the output of the second line memory 50 by one line
, A first delay group circuit 46, a second delay group circuit
, And an adder 52 that adds the outputs of the third delay group circuit 51.

In the second delay group circuit 49,
The first multiplier 41 multiplies the output of the first line memory 48 by a coefficient signal K21 from the CPU 31, and the second multiplier 43 applies the RGB digital signal from the first delay circuit 42 to the RGB digital signal from the CPU 31. Is multiplied by the coefficient signal K22 of
Multiplier 45 multiplies the RGB digital signal from the second delay circuit 44 by the coefficient signal K23 from the CPU 31.

Further, in the third delay group circuit 51,
The first multiplier 41 multiplies the output of the second line memory 50 by a coefficient signal K31 from the CPU 31, and the second multiplier 43 outputs the RGB digital signal from the first delay circuit 42 to the RGB digital signal from the CPU 31. Is multiplied by the coefficient signal K32 of
Multiplier 45 multiplies the RGB digital signal from the second delay circuit 44 by the coefficient signal K33 from the CPU 31.

(Operation) Next, the operation of the present embodiment configured as described above will be described.

Insert the insertion portion 7 of the scope 3 into the body cavity,
The illumination light is supplied from the light source device 4 to the scope 3, and the endoscope image transmitted to the eyepiece is captured by the CCD 11 of the camera head 2. The CCU 5 processes the image signal and displays an endoscope image on a monitor.

As shown in FIG. 5, the insertion portion 7 of the scope 3
Since the image guide fiber bundle 60 for transmitting an endoscope image passing through the plurality of image guide fibers 63 is configured by periodically arranging a plurality of image guide fibers 63 including a core 61 and a clad 62, a stitch pattern is formed by the clad 62. Is displayed.

The CPU 31 outputs to the spatial frequency characteristic variable circuit 24 coefficient data in the form of a matrix represented by the following equation (1), which is stored in advance in a built-in ROM or the like, based on the instruction signal from the SW 32. I do.

[0034]

(Equation 1) At this time, based on the instruction from the SW 32, the CPU 31
Outputs to the selector 55 a select signal for designating the amount of delay of the first delay circuit 42 and the second delay circuit 44 shown in FIG. Thereby, the first delay circuit 42
And the second delay circuit 44 calculates 1C of CK from the TG 29.
One of the outputs delayed from K to 4CK will be selected.

That is, in the spatial frequency characteristic variable circuit 24, the delay amount in the first delay circuit 42 and the second delay circuit 44 is set by the select signal. A filter having frequency characteristics will be configured.

For example, in the first delay circuit 42 and the second delay circuit 44, the transfer function H1 (ω) at one-stage delay when 1CK is delayed is z = e ^j ω ^tos (ω = 2πf).
Then

H1 (ω) = − 0.25z + 1−0.25z− ¹ (2)

Similarly, the transfer function H2 (ω) with a two-stage delay when the delay is 2CK, the transfer function H3 (ω) with a three-stage delay when the delay is 3CK, and the four-stage when the delay is 4CK. The transfer function H4 (ω) at the delay is

H 3 (ω) = − 0.25z ² + 1−0.25z ⁻² (3)

[Number 4] ^{H3 (ω) = - 0.25z 3} + 1-0.25z -3 ... (4)

H4 (ω) = − 0.25z ⁴ + 1−0.25z ⁻⁴ (5)

These transfer functions H1 (ω), H2 (ω),
When the sampling frequency is 14.318 MHz, the frequency characteristics of H3 (ω) and H4 (ω)
Assuming that the vertical axis is the gain, the solid lines in FIGS. 6A, 6B, 6C, and 6D are as shown in FIG. 6A, and the gain in a desired frequency band can be reduced.

That is, while observing the monitor image,
2, the coefficient data is set as shown in the equation (1), and the amount of delay in the first delay circuit 42 and the second delay circuit 44 is selected. As a filter having any of the frequency characteristics of the functions H1 (ω), H2 (ω), H3 (ω), and H4 (ω), the stitch pattern by the image guide fiber bundle 60 is removed from the endoscope image.

Further, the space f characteristic variable circuit 24 includes a CP
The matrix enhancing coefficient data shown in the following equation (6) stored in advance in the ROM or the like of the U31 can serve as an outline emphasizing circuit.

[0041]

(Equation 6) That is, the transfer functions H1 (ω), H2 (ω),
H3 (ω) and H4 (ω) are

H1 (ω) = 0.25z-1 + 0.25z- ¹ (7)

H 2 (ω) = 0.25z ² -1 + 0.25z ^-2 (8)

H3 (ω) = 0.25z ³ -1 + 0.25z ^-3 (9)

H4 (ω) = 0.25z ⁴ -1 + 0.25z ^-4 (10), and the transfer functions H1 (ω), H2 (ω), H
The frequency characteristics of 3 (ω) and H4 (ω) are shown in FIGS. 6 (a), (b), (c) and (c), where the horizontal axis represents frequency and the vertical axis represents gain when the sampling frequency is 14.318 MHz. As indicated by the broken line d), the gain in the desired frequency band can be increased, and the contour can be enhanced.

In the present embodiment, the matrix-form coefficient data stored in advance in the built-in ROM or the like of the CPU 31 is represented by Equations (1) and (6). However, the present invention is not limited to this. According to the above, a plurality of types of coefficient data which can remove the stitch pattern by the image guide fiber bundle 60 from the endoscope image may be stored.

In this case, by providing the scope 3 with an identification means for identifying the type, the CPU 31 may identify the type of the scope 3 and select the optimum coefficient data.

As shown in FIG. 2, a serial interface (hereinafter, serial I / F) 71 is provided in the CCU 5.
May be provided, and coefficient data may be written into the CPU 31 by input means such as a keyboard 73 of a personal computer (PC) 72.

(Effect) According to the present embodiment, the CPU 31 specifies the coefficient data and the amount of delay in the first delay circuit 42 and the second delay circuit 44, and thereby the spatial frequency characteristic variable circuit Since the spatial frequency characteristic of the spatial frequency characteristic 24 is variable, the spatial frequency characteristic variable circuit 24 normally plays a role of an outline emphasizing circuit, and when removing the stitch pattern by the image guide fiber bundle 60, the spatial frequency characteristic can be changed to a desired value. Since a stitch pattern removing filter with a reduced frequency band gain can be used, there is no need to provide a dedicated filter for removing the stitch pattern by the image guide fiber bundle 60, so that the apparatus can be configured at low cost. it can.

[Supplementary note] (Supplementary note 1) A fiber type endoscope having an image guide fiber bundle for transmitting an endoscope image to an eyepiece in an insertion portion inserted into a lumen, and is detachably attached to the eyepiece. In an endoscope apparatus equipped with an imaging unit mounted on the imaging unit for imaging the endoscope image, and a signal processing unit for performing signal processing on a video signal from the imaging unit, the signal processing unit can change a spatial frequency characteristic. An endoscope apparatus comprising a spatial filter that performs the following.

(Appendix 2) The endoscope apparatus according to Appendix 1, further comprising control means for controlling the spatial frequency characteristic of the spatial filter.

(Additional Item 3) The endoscope apparatus according to Additional Item 2, further comprising an instruction unit for instructing the control unit to perform control.

(Additional Item 4) The endoscope apparatus according to Additional Item 1, wherein the spatial filter can be changed to a spatial frequency characteristic for removing at least a stitch pattern on an image due to the image guide fiber bundle.

(Supplementary Note 5) The spatial filter can be changed into at least a first spatial frequency characteristic for removing a stitch pattern on an image due to the image guide fiber bundle and a second spatial frequency characteristic for performing contour enhancement. 2. The endoscope apparatus according to claim 1, wherein

[0051]

As described above, according to the endoscope apparatus of the present invention, the spatial filter provided in the signal processing means has a variable spatial frequency characteristic. The effect is that the influence can be eliminated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a CCU in FIG. 1;

FIG. 3 is a configuration diagram showing a configuration of a space f characteristic variable circuit of FIG. 2;

FIG. 4 is a configuration diagram showing a configuration of a first delay circuit in FIG. 3;

FIG. 5 is a configuration diagram showing a configuration of an image guide fiber bundle inserted through an insertion portion of the scope of FIG. 1;

FIG. 6 is a diagram illustrating an example of a frequency characteristic of the spatial frequency characteristic variable circuit of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Endoscope apparatus 2 ... Camera head 2a ... Adapter 3 ... Scope 4 ... Light source apparatus 5 ... CCU 6 ... TV monitor 7 ... Insertion part 8 ... Operation part 9 ... Light guide cable 11 ... CCD 12 ... Camera cable 13 ... CCD Driver 14 Preamplifier 15 Preprocessing circuit 16 A / D conversion circuit 17, 28 I. L 18 Y / C separation circuit 19 Color difference LPF 20 Line-sequential synchronization circuit 21 Color separation circuit 22 AGC & painting circuit 23 Knee & γ correction circuit 24 Space f characteristic variable circuit 25 Encoder 26 75 Ω driver 27 ... SSG 29 ... TG 31 ... CPU 32 ... SW 41 ... First multiplier 42 ... First delay circuit 43 ... Second multiplier 44 ... Second delay circuit 45 ... Third multiplier 46 ... First Delay group circuits 47, 52 adder 48 first line memory 49 second delay group circuit 50 second line memory 51 third delay group circuit 55, 56, 57, 58 delay elements 59: selector 60: image guide fiber bundle 61: core 62: clad

Claims (1)

[Claims] A fiber endoscope having an image guide fiber bundle for transmitting an endoscope image to an eyepiece in an insertion portion inserted into a lumen; and the endoscope detachably attached to the eyepiece. In an endoscope apparatus including an imaging unit that captures a mirror image and a signal processing unit that performs signal processing on a video signal from the imaging unit, the signal processing unit includes a spatial filter that changes a spatial frequency characteristic. An endoscope apparatus characterized in that: