JPH088904B2 - Video endoscopy equipment - Google Patents

Description

The present invention relates to a video endoscope apparatus provided with a recursive filter for reducing noise.

[Prior Art] In recent years, an electronic video endoscope (hereinafter referred to as an electronic endoscope or electronic scope) using a solid-state imaging device such as a CCD (charge coupled device) as an imaging means has been put into practical use.

By the way, a conventional video endoscope is disclosed in, for example, JP-A-61-1.
As described in 63788, the video signal generated by the process circuit is directly supplied to a monitor or a photographing device.

[Problems to be Solved by the Invention] In the above-mentioned conventional example, since no means for removing noise is provided, when a particularly small image pickup device such as a video endoscope for bronchus is used, The cell area becomes smaller, the sensitivity decreases, the S / N becomes worse, and there is a drawback that noise is noticeable on the screen.

Also, with video endoscopes, unlike ordinary TV cameras,
Since the imaging device is at the tip of the endoscope and the signal processing process circuit is at the camera control unit (hereinafter referred to as CCU) side, and the distance between them is very large, noise is likely to be mixed in the middle of the process. Moreover, because it is used in combination with a therapeutic electrosurgical unit, the high-frequency noise of this electrosurgical unit is mixed in.
S / N decreases. In this case, the longer the length of the video endoscope, the greater the tendency that the S / N becomes worse.

Furthermore, in the case of a TV camera that is attached to the eyepiece of an optical endoscope, a video endoscope device that can be combined with various endoscopes can be considered, but it is connected to an endoscope that can only obtain dark images. In that case, the illuminance of the (image pickup) plate surface of the image pickup element was low, so that the S / N was also deteriorated and the screen was likely to be noisy.

The present invention has been made in view of the above points, and an object thereof is to provide a video endoscope apparatus capable of making noise less noticeable.

[Means and Actions for Solving Problems] In the video endoscope apparatus according to the present invention, a video endoscope apparatus for displaying an endoscopic image on a monitor based on an output signal of an image sensor for converting an optical image into an electric signal. A process circuit for processing the output signal of the image sensor to output at least a first digital video signal and a second digital video signal each containing different signal components,
A first coefficient unit in which a coefficient is variably set and which multiplies the first digital video signal by the set coefficient and outputs the first digital video signal;
And a first adder having a second input end to which the output of the first coefficient unit is input, and a first adder delaying the output signal of the first adder by a predetermined time. Delay circuit of
A coefficient is variably set, and a second coefficient unit for multiplying the output signal of the first delay circuit by the set coefficient and inputting it to the second input terminal of the first adder; And a third coefficient multiplier for outputting the second digital video signal by multiplying the second digital video signal by a set coefficient, and the third coefficient multiplier having first and second input terminals. A second adder to which the output of the second adder is input, a second delay circuit that delays the output signal of the second adder for a predetermined time, and a coefficient is variably set to set the output signal of the second delay circuit. A fourth coefficient unit which multiplies the obtained coefficient by a coefficient and inputs the result to the second input terminal of the second adder, at least the output signal of the first adder and the second adder The display unit displays the endoscopic image on the monitor on the basis of the output signal.

EXAMPLES The present invention will be specifically described below with reference to the drawings.

1 and 2 relate to the first embodiment of the present invention.
The figure shows the configuration of the video endoscope apparatus of the first embodiment, and the second embodiment
The figure shows the block configuration of a recursive filter.

As shown in FIG. 1, the video endoscope apparatus 1 of the first embodiment.
Is a video endoscope (hereinafter referred to as a videoscope) 2
And CCU3 that performs signal processing for this videoscope 2.
And a light source unit 4 for supplying illumination light to the video scope 2, a color monitor 5 for displaying a video signal output from the CCU 3, and a color image displayed by the display means so that a still image can be captured by the image capturing means. And device 6.

The video scope 2 has an elongated insertion portion 7 that can be inserted into a body cavity or the like, and a light guide 8 that transmits illumination light is inserted into the insertion portion 7, and the light guide 8 is further operated. The universal cord extended from the section is inserted so that it can be connected to the light source unit 4. A light source lamp 9 is housed in the light source unit 4, and white light from the light source lamp 9 passes through a rotary color filter 12 that is driven to rotate by a motor 11,
It is condensed by the condenser lens 13 and is irradiated onto the incident end surface of the light guide 8.

The rotary color filter 12 is configured by a disk-shaped filter frame rotated by a motor 11 provided with three fan-shaped openings, and red, green, and blue color transmission filters are attached to the respective openings. Has been done. Therefore, by passing through the rotating color filter 12, white light is sequentially red,
It is made into green and blue colored light (also referred to as frame sequential light) and is irradiated onto the incident end surface of the light guide 8.

Red, green supplied to the incident end face of the light guide 8,
The blue surface-sequential light is transmitted to the emission end surface of the light guide 8 and is emitted toward the subject. The subject illuminated by the field-sequential light is imaged on the image pickup surface of the CCD 15 (as an image pickup element) arranged on the focal plane of the objective lens 14 attached to the tip of the insertion section 7. This CCD 15 converts an optical image into an electric signal and accumulates it as an electric charge. Then, by applying a drive signal from the drive circuit 16 in the CCU 3, the video signal read from the CCD 15 is input to the process circuit 17.

The process circuit 17 double-samples the output signal from the CCD 15 and then further performs γ correction and the like, and further converts it into an 8-bit digital signal by an A / D converter (not shown), and then an R, G, B frame memory. Remember. Then, when one frame of video signal data is stored in the R, G, B memory, these are read out at the same time and are output from the process circuit 17 as a predetermined video signal, in this case, R, G, B digital video signals. Is output. These 8-bit R, G, B digital signals are input to the noise removing circuit 18, noise is removed, and further analogized predetermined color signals R ',
G'and B'are displayed in color on the color monitor 5 and input to the photographing device 6 for recording.

The photographing device 6 is designed so that a still camera 20 can photograph the color image displayed on the color monitor as a display means and the display 19 of the color monitor.

By the way, the noise removing circuit 18 is composed of R, G, and B recursive filters 21, 22, and 23. These R
, G, and B recursive filters 21, 22, and 23 have the same configuration,
For example, the configuration of the R recursive filter 21 is shown in FIG.

The recursive filter 21 has a general recursive comb filter configuration.

That is, the input signal (8-bit R signal in this case) is (1
-K) Multiply by the coefficient multiplier 24, and then adder 1-K
It is input to 25 and is added to the output signal of the coefficient multiplier 26 for multiplying by K. The output of the adder 25 is input to the 1-frame delay circuit 27 and the D / A converter 28.

The output of the 1-frame delay circuit 27 is input to the coefficient unit 26 that multiplies K times. The output of the D / A converter 28 is input to the LPF 29, the unnecessary harmonics are removed, and the output is output from the cyclic filter 21.

The coefficient K in the coefficient units 24 and 26 can be variably set from the outside in the range of 0 to 0.5, for example. Also, for example, K = 0.5
You may fix it to.

S / N is 10 log by the above cyclic filters 21, 22, 23
Since it is improved by (1 + k) / (1-K) (for example, 4.8 dB when K = 0.5), noise is reduced and the image becomes easy to see.

FIG. 3 is a recursive filter according to the second embodiment of the present invention.
31 is shown.

This second embodiment is for R, G, B in the first embodiment.
It is a recursive filter 21, 22, 23 for use, that is, a recursive filter 31 used in place of that shown in FIG.

The cyclic filter 31 differs from the cyclic filter 21 shown in FIG.
This comparison signal is input to the motion detection circuit 33 in comparison with the image before the frame, and the coefficient K is controlled to be large when the motion is small and is controlled to be small when the motion is large.

That is, as shown in FIG. 3, the input signal is input to the coefficient unit 24 and to the arithmetic unit 32, and the 1-frame delay circuit 27
And the subtracted signal is divided by the output signal of the 1-frame delay circuit 27, and a signal is input to the motion detection circuit 33. The motion detection circuit 33 sets the coefficient K to the coefficient units 24 and 26 in accordance with the output signal of the arithmetic unit 32 when the output signal is close to 1, and decreases the coefficient K when the output signal is far from 1. Set. This motion detection circuit
33, the coefficient K is variably set so that the current image is emphasized when the movement is fast (that is, the ratio of adding the images of one frame before is reduced) to prevent the image from being blurred. When the movement is small, the amount of enhancement of the image one frame before is increased to increase the S / N.

 FIG. 4 shows a third embodiment of the present invention.

In the third embodiment, the CCU 41 incorporates a process circuit 42, and the R, G, B signals passed through the process circuit 42 are input to the photographing device 43. This process circuit 42 is, for example, the first
It has the same configuration as the process circuit 17 in the embodiment.

The image capturing device 43 includes, for example, the noise removing circuit 18 in the first embodiment, a drive circuit 44, a controller 45, a cathode ray tube 46, and a camera 47 for capturing an image displayed on the cathode ray tube 46.

The drive circuit 44 and the camera 47 are controlled by the controller 45, and the image displayed on the cathode ray tube 46 by the drive circuit 44 is photographed by the camera 47.

In the third embodiment, the noise removing circuit 18 is not provided in the CCU 41, but is provided in the photographing device 43, for example.

Further, the noise removal circuit 18 may be provided in a device independent of the CCU 41, or may be a unit that can be provided on the output side of the CCU 41 before the monitor.

 FIG. 5 shows the main part of the fourth embodiment of the present invention.

This embodiment shows a video endoscope device 54 in which an external TV camera 53 is connected to an eyepiece portion 52 of a fiberscope 51.

In the fiberscope 51, a light guide 56 is inserted into an elongated insertion portion 55, and this light guide 56 is further inserted into a light guide cable extended from the operation portion to the light source unit 57 with its incident end. , The white light of the lamp 58 is condensed and emitted by the condenser lens 59.

The illumination light transmitted by the light guide 56 is emitted from the emission end to the subject side through the light distribution lens.
Then, the illuminated subject is imaged on the incident end surface of the image guide 62 by the objective lens 61 attached to the tip of the insertion portion 55. The optical image of the incident end face of the image guide 62 is transmitted to the emitting end face and magnified by the eyepiece lens 63 arranged facing the emitting end face. An external TV camera 53 can be connected to the eyepiece section 52 in which the eyepiece lens 63 is housed, and an imaging lens 64 and a CCD 65 are housed in the TV camera 53. Image guide with this imaging lens 64
The optical image transmitted at 62 is formed on the image pickup surface of the CCD 65. This C
A color separation mosaic filter 66 is attached to the imaging surface of the CD 65. The mosaic filter 66 is configured by arranging red, green, and blue color transmission filters in a mosaic pattern, and separates colors for each pixel. The electric signal photoelectrically converted by the CCD 65 is read by a drive signal from a CCD drive circuit (not shown) in the CCU 67 and input to the process circuit 68. The process circuit 68 double-samples the signal from the CCD 65, generates the luminance signal Y through the LPF, generates the time series color signal through the BPF, etc., and further passes through the matrix circuit to perform the luminance signal Y and color difference signal R -Y, BY are output.

The luminance signal Y and the color difference signals RY and BY output from the process circuit 68 are input to the noise removing circuit 72 via the changeover switch 71. The noise removing circuit 72 is composed of recursive filters 73, 74 and 75.
3, 74 and 75 have the same structure, for example, a structure in which an A / D converter is provided on the input side of the filter 21 shown in FIG.

A changeover switch 76 is also provided on the output side of the noise removing circuit 72, and the output through this changeover switch 76 is input to the monitor.

The changeover switches 71 and 76 can be controlled by a recursive filter ON / OFF switch 77 provided in the TV camera 53. This ON / OFF switch 77
When turned on, the output of the process circuit 68 is input to the monitor after passing through the noise removal circuit 72, and when turned off, the output of the process circuit 68 does not pass through the noise removal circuit 72 as shown in FIG. Then, it is input to the monitor.

According to this embodiment, ON / OFF of the recursive filter can be selected, but a means for selectively setting the magnitude of the coefficient of the recursive filter may be provided.

In the fourth embodiment, the external TV camera 53 is provided with the ON / OFF switch 77 for the recursive filter. However, as shown in FIG. An / OFF switch 83 may be provided. In this case, if a mosaic filter is arranged in front of the image pickup surface of the CCD as the video scope 81, it can be used instead of the fiber scope 51 shown in FIG. In addition, as shown in FIG. 1, even if the CCD 15 has a frame-sequential imaging method in which a mosaic filter is not provided on the imaging surface,
The same function can be realized by interposing change-over switches before and after the noise removing circuit 18 shown in the figure. Further, instead of interposing a changeover switch, a coefficient unit (for example, reference numerals 24 and 2 in FIG. 2 is used).
The coefficient K of 6) may be set to 0 by the ON / OFF switch 83 or the like so that the selection substantially equivalent to the case where no recursive filter is passed can be performed.

Although the cyclic filter in each of the above-described embodiments has a one-frame delay, the present invention is not limited to this, and one-field delay may be used.

Further, according to the present invention, not only the R, G, B color signals but also the luminance signal and the chroma signal may be noise-removed through a cyclic filter and then converted into a composite video signal. Alternatively, the composite video signal may be directly filtered.

The recursive filter is not limited to the digital type and may be the analog type.

In addition, for the signals read from the image sensor such as CCD,
You may make it pass through an analog type recursive filter directly.

[Effects of the Invention] As described above, according to the present invention, noise reducing means using a recursive filter is provided, so that noise can be suppressed and an image with good S / N can be obtained.

[Brief description of drawings]

1 and 2 relate to the first embodiment of the present invention. FIG. 1 is a block diagram of the first embodiment, FIG. 2 is a block diagram showing the configuration of a recursive filter, and FIG. 3 is the present invention. Is a block diagram showing the configuration of a recursive filter in the second embodiment of the present invention, FIG. 4 is a configuration diagram of the third embodiment of the present invention, FIG. 5 is a configuration diagram of the fourth embodiment of the present invention, and FIG. It is a schematic side view which shows the videoscope provided with the ON / OFF switch of a recursive filter. 1 ... Video endoscope device, 2 ... Video scope 3 ... CCU, 4 ... Light source unit 5 ... Color monitor, 6 ... Imaging device 15 ... CCD, 17 ... Process circuit 18 ... Noise removal Circuits 21, 22, 23 ... Cyclic filters

Claims (1)

[Claims] 1. A video endoscope apparatus for displaying an endoscopic image on a monitor based on an output signal of an image pickup device for converting an optical image into an electric signal, wherein the output signal of the image pickup device is processed to obtain different signals. A process circuit for outputting at least a first digital video signal and a second digital video signal including a signal component, and a coefficient variably set, and the first digital video signal is multiplied by the set coefficient and output. A first coefficient unit, a first adder having first and second input terminals, and an output of the first coefficient unit being input to the first input terminal; and a first adder A delay circuit for delaying the output signal of the first delay circuit for a predetermined time, and a coefficient variably set, the output signal of the first delay circuit is multiplied by the set coefficient, and the second delay circuit of the first adder
A second coefficient unit for inputting to the input end of the third coefficient unit, a third coefficient unit for variably setting the coefficient and multiplying the second digital video signal by the set coefficient, and outputting the multiplied coefficient; A second adder having a first input terminal to which the output of the third coefficient unit is input, and a second delay for delaying an output signal of the second adder for a predetermined time. A circuit, a coefficient is variably set, the output signal of the second delay circuit is multiplied by the set coefficient, and the second signal of the second adder is multiplied.
A fourth coefficient unit for inputting to an input end of the monitor, and displaying an endoscopic image on the monitor based on at least the output signal of the first adder and the output signal of the second adder. A video endoscopic device characterized in that