JP2946349B2 - Electronic endoscope device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus, and more particularly, to an electronic endoscope apparatus capable of stopping an image as required.

[Conventional technology]

An electronic endoscope used for medical or industrial use includes a scope section, a processor, and a monitor device, and an insertion section of the scope section is inserted into a body cavity or the like, and is built in or independent of the processor. Illuminates the observation target with illumination light, and reflects the reflected image from the observation target.
A video signal is formed by photoelectric conversion by a solid-state imaging device such as a CCD, and the obtained video signal is read out from the imaging device and transmitted to a processor. The color display is used.

Here, in order to reduce the diameter of the insertion part of the scope part,
In order to use one image sensor and improve the resolution, images of each color of red (R), green (G) and blue (B) are formed for each field, and these are superimposed. An image display device that drives an image sensor by a so-called frame sequential method for displaying an image is used.

By the way, in this type of electronic endoscope apparatus, generally, a light source for irradiating illumination light from the distal end of the scope becomes a noise source, and noise is mixed in a video signal. In particular, in the case of a moving image, the noise is generated at random and is inconspicuous, but in the case of a still image in which an image is frozen, the noise always appears at a fixed position in a screen, so that the image quality is deteriorated. There's a problem.

[Problems to be solved by the invention]

The conventional electronic endoscope apparatus does not remove the noise, and cannot obtain a good still image. Also,
In the field of video processing technology, a noise reducer circuit for reducing noise mixed in a video signal is known. This noise reducer circuit uses autocorrelation between fields of a video signal, and is effective for a still image, but has an essential problem that a residual image occurs in a moving image. Further, this kind of noise reducer circuit is not used in a field sequential type electronic endoscope apparatus.

The present invention has been made in view of such circumstances, and particularly when recording a still image or performing an endoscope determination based on a still image, an electronic endoscope capable of obtaining a good still image with a reduced noise level. It is an object to provide a mirror device.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a means for capturing an image of an observation target by a solid-state imaging device built in a tip of a scope to obtain an analog video signal indicating the observation target, and An analog-to-digital converter, a memory for storing the converted digital video signal, and delay means for delaying the digital video signal read from the memory by a predetermined field time. A noise component is obtained based on a difference between the output digital video signal and the digital video signal delayed by the delay means, and the obtained noise component is subtracted from the digital video signal read from the memory to obtain a noise component. A noise reducer circuit for suppressing noise of a digital video signal; Switching means for inputting an image signal and a digital video signal passing through the noise reducer circuit and switching and outputting one of the digital video signals; and converting the digital video signal output from the switching means into an analog video signal D / A converter, means for displaying an image indicating the observation target unit based on the converted analog image signal, freeze instruction means for outputting a phrase instruction for switching from a moving image to a still image, and the freeze instruction means When the freeze command is not output, the switching unit is switched so that the switching unit outputs a digital video signal that does not pass through the noise reducer circuit. When the freeze command is output from the freeze command unit, the memory is stored in the memory. The updating of the content is stopped, and the noise reduction Characterized in that and a control means for switching said switching means so as digital video signal through the circuit is outputted.

[Action]

According to the present invention, a noise reducer circuit is provided between a memory that stores a video signal and a D / A converter that converts a digital video signal into an analog video signal, and only when a freeze command is output from freeze command means. In addition, noise mixed into a video signal read from the memory through the noise reducer circuit through the noise reducer circuit is reduced, thereby obtaining a good still image.

〔Example〕

Hereinafter, preferred embodiments of an electronic endoscope apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall configuration of an electronic endoscope apparatus according to the present invention. As shown in FIG. 1, the electronic endoscope device includes a scope unit 10, a processor 20, and a monitor device 30.

To the processor 20, R, G,
An illumination device for sequentially irradiating the B light to the observation target portion 14 is built in. That is, the white light from the light source 22 lit by the light source lighting circuit 21 is guided to one end 12A of the light guide 12 via the condenser lens 23 and the rotating color filter 24.

The rotating color filters 24 each have a central angle of 120 ° R,
It has three color filters of G and B and is rotated by a motor 25. This motor 25 is a synchronous signal generation circuit
By the motor control circuit 26 that inputs the synchronization signal from 27,
It is controlled to rotate at a predetermined rotation speed (for example, 20 rps). As a result, the light from the light source 22 is sequentially changed via the rotating color filter 24 at a cycle of 1/60 second R,
The light becomes illumination light of each color of G and B, and is applied to the observation target portion 14 via the light guide 12.

An objective lens 15 and a solid-state imaging device (CCD) 16 are provided at the tip of the scope unit 10, and the objective lens 15 includes R, G, B
An image of the observation target portion 14 illuminated by each illumination light is formed on a light receiving portion of the CCD 16, and the CCD 16 is driven by a driving pulse applied from the CCD driver 28 via the signal line 17, and photoelectrically converts incident light to each of them. An RGB video signal corresponding to the illumination light is output to the signal processing circuit 29 via the signal line 18.

The signal processing circuit 29 of the processor 20 performs signal processing such as simultaneous conversion of a plane-sequential RGB video signal input from the CCD 16 and outputs the signal to the monitor device 30.

FIG. 2 is a block diagram showing details of the processor.

In the figure, a plane-sequential RGB video signal input from the CCD 16 is applied to an A / D converter 41 via a process circuit 40 having a sample hold circuit, a γ correction circuit, a clamp circuit, and the like. The A / D converter 41 converts an input RGB video signal (analog signal) into a digital signal one pixel at a time, and converts the digital signal into R, G, B field memories 42, 43, 44.
Output to

The field memories 42, 43, 44 are controlled by a memory control circuit 45. That is, the memory control circuit 45 performs the RGB control based on the vertical synchronization pulse applied from the synchronization signal generation circuit 27.
The video signals are sequentially stored in the field memories 42, 43 and 44, and R-EN pulses, G-EN pulses and B-EN pulses for updating the stored contents of the memories are output.

The video signals sequentially written in the field memories 42, 43, 44 are simultaneously read out, and are connected to the switches A, 64, 65, 66 via the contact points A of the switches 64, 65, 66 and the noise reducers 61, 62, 63. Is applied to each contact B.

The control circuit 67 controls the memory control circuit 45, the noise reducer circuits 61, 62, 63, and the switches 64, 65, 66. A freeze command signal from a foot switch in a scope operation unit or a control switch on a processor front panel is used. Is added as appropriate.

The control circuit 67 switches the switches 64, 65, and 66 to the contact A side when the freeze command signal is not input. On the other hand, when the freeze command signal is input, the control circuit 67 stores each memory output from the memory control circuit 45. The pulse output for updating the content is stopped, and the switches 64, 65, and 66 are each switched to the contact B side to select a signal passed through the noise reducer circuits 61, 62, and 63. The noise reducer circuit 6
Details of 1, 62 and 63 will be described later.

The video signal selected by the switches 64, 65 and 66 is a process circuit having D / A converters 46, 47 and 48, and a clamp circuit and an amplifier circuit for adjusting the respective levels.
It is output from video output terminals 53, 54, 55 via 50, 51, 52.

Next, details of the noise reducer circuits 61, 62, 63 will be described.

FIG. 3 is a block diagram showing one embodiment of the noise reducer circuit 61.

As shown in the figure, this noise reducer 61
It uses the auto-correlation between fields of the video signal to reduce noise components with little auto-correlation contained in the video signal, and includes subtractors 61A and 61B, a limiter 61C, and a multiplier 6
1D, switch 61E, delay circuit 61F and field memory 61
Consists of G.

The switch 61E is controlled by a signal from the control circuit 67. The switch 61E is switched to the contact A side when monitoring a normal moving image, and is connected when a freeze command signal is input to monitor or record a still image. Switch to B side.

When the switch 61E is switched to the contact A side,
The video signal read from the field memory 42 is subtracted.
The data is stored in the field memory 61G via the switch 61E, the switch 61E, and the delay circuit 61F. Here, the delay circuit 61F delays the input video signal by three fields (1/20 second) and outputs it to the field memory 61G. As a result, the stored contents of the video signal read from the field memory 42 are updated every three fields.
The video signal three fields before (before updating) is always stored in G.

When the control circuit 67 receives the freeze command signal, the contents stored in the field memory 42 are fixed as described above, and the switch 61E is switched to the contact B side.

The video signal read from the field memory 42 is applied to the subtracters 61A and 61B, and the video signal read from the field memory 61G is applied to the subtractor 61B. Subtractor 6
1B detects only noise by subtracting the video signal three fields before (these video signals have high correlation) from the video signal read from the field memory 42, and detects this noise via a limiter 61C as a multiplier. Output to 61D.

The multiplier 61D multiplies the noise subjected to the limiter by a predetermined count K (0 <K <1), and outputs the result to the subtractor 61A.

The subtractor 61A outputs a video signal with reduced noise components by subtracting the noise obtained as described above from the video signal read from the field memory. This video signal is stored again in the field memory 61G via the switch 61E. Then, by repeatedly performing the above operation, a significant noise reduction can be performed.

The number of repetitive operations for noise reduction may be set in advance by the processor operation unit, and after the set number of repetitive operations, the switch 61E may be switched to the neutral position. The noise reducer circuits 62 and 63 have the same configuration as the noise reducer circuit 61 described above.

As described above, when the freeze command signal is input to the control circuit 67, the switches 64, 65,
Each of the switches 66 is switched to the contact B side, and the noise-reduced video signal is guided to the D / A converters 46, 47, 47 and 48 via the noise reducers 61, 62 and 63.

As a result, when recording or monitoring a still image,
A high-quality still image with a reduced noise level can be obtained.

FIG. 4 is a main part block diagram showing another embodiment of the electronic endoscope apparatus according to the present invention.

In the figure, a matrix circuit 70 generates a luminance signal Y and color difference signals (RY) and (BY) from RGB signals, and outputs these signals via A / D converters 71, 72 and 73 to a field. The data is stored in the memories 74, 75, and 76. These field memories 74, 75, and 76 store the input video signal and read out the stored signal at the same time. When a freeze command is issued similarly to the above-described field memories 42, 43, and 44, the storage is performed. No content update is performed.

The signals read from the field memories 74, 75, 76 are switches 80, 81, 82 when there is no freeze command.
Is applied to the D / A converters 83, 84, 85, and when there is a freeze command, the D / A converters 83, 84, 81, 82 through the noise reducer circuits 77, 78, 79 and the switches 80, 81, 82. Added to 84 and 85.

Luminance signal Y converted to an analog signal by D / A converter 83
Is the sum of the synchronization signal S by the adder 86, while the D / A
The color difference signals (RY) and (BY) converted into analog signals by the converters 84 and 85 are subjected to quadrature two-phase modulation by a modulator 87 modulated by a 3.58 MHz chrominance subcarrier and added to produce a chroma signal. C. The luminance signal (Y + S) to which the synchronizing signal S is added and the chroma signal C are added to form an NTSC video signal.

〔The invention's effect〕

As described above, according to the electronic endoscope apparatus of the present invention, only when the image is frozen by the freeze command, the video signal corresponding to the still image is caused to pass through the noise reducer circuit. A good still image with reduced noise level can be obtained.
On the other hand, in the case of a moving image, the video signal is prevented from passing through the noise reducer circuit, so that an afterimage does not occur. In the case of a moving image, the noise included in the video signal is not so noticeable on the monitor.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of an electronic endoscope apparatus according to the present invention, FIG. 2 is a block diagram showing details of a processor in FIG. 1, and FIG. 3 is a detail of a noise reducer circuit in FIG. FIG. 4 is a main part block diagram showing another embodiment of the electronic endoscope apparatus according to the present invention. 14: Observation target section, 16: Solid-state image sensor (CCD), 22: Light source, 42, 43, 44, 61G, 74, 75, 76: Field memory, 45: Memory control circuit, 46, 47 , 48, 83, 84, 85… D / A converter, 61, 62, 63, 77, 78, 79… Noise reducer circuit, 61A, 61B… Subtractor, 61C… Limiter, 61D… Multiplication , 61E ... switch, 61F ... delay circuit, 64, 65, 66, 80, 81, 82 ... switch, 67 ... control circuit.

Claims (1)

(57) [Claims] A means for capturing an image of an object to be observed by a solid-state image pickup device built in a tip of a scope to obtain an analog video signal indicating the object to be observed; and converting the analog image signal into a digital image signal.
An A / D converter; a memory for storing the converted digital video signal; and a delay unit for delaying the digital video signal read from the memory by a predetermined field time. A noise component is obtained based on a difference between the digital video signal and the digital video signal delayed by the delay means, and the digital video signal is obtained by subtracting the obtained noise component from the digital video signal read from the memory. A noise reducer circuit that suppresses the noise of the digital video signal read from the memory and a digital video signal that has passed through the noise reducer circuit, and a switching unit that switches and outputs one of the digital video signals. Converting the digital video signal output from the switching means into an analog video A D / A converter that converts the signal into a signal, a unit that displays a video indicating the observation target unit based on the converted analog video signal, a freeze command unit that outputs a freeze command to switch from a moving image to a still image, When the freeze command is not output from the freeze command means, the switching means is switched so that a digital video signal that does not pass through the noise reducer circuit is output from the switching means, and the freeze command is output from the freeze command means. Control means for stopping updating of the storage contents of the memory and switching the switching means so that a digital video signal is output from the switching means via the noise reducer circuit. Endoscope device.