JP2017169897A - Electronic endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly acquire a stroboscope image without changing a light emission timing of a stroboscope.SOLUTION: An electronic endoscope system 10 comprises: an imaging device 15; a scope controller 16; and a light source device 22. The light source device 22 intermittently irradiates an observation site with illumination light. The scope controller 16 detects an irradiation period of the illumination light and a pixel signal output period of the imaging device 15. The scope controller 16 determines whether or not the irradiation period and the pixel signal output period overlap each other. When the irradiation period and the pixel signal output period overlap each other, the scope controller 16 performs noise correction processing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electronic endoscope system that performs stroboscopic imaging by intermittently irradiating illumination light.

  2. Description of the Related Art Conventionally, an endoscope system including a strobe light source is known for observing a subject that cannot be observed with a normal light source, for example, a vocal cord that vibrates at a high frequency. In this stroboscope photography, the stroboscopic light source irradiates the observing site that is vibrating with intermittent illumination light synchronized with the vibration period of the vocal cords. The strobe emission timing is determined according to the period of the vocal cord vibration waveform, and by controlling the light emission period so that the phase is shifted by a predetermined amount with respect to the vocal cord vibration waveform, the vibrating vocal cord (See, for example, Patent Document 1).

JP 2004-97442 A

  However, in the above configuration, since the pixel signal output timing and the strobe light emission timing of the image sensor are separately determined, a period in which the pixel signal output timing and the strobe light emission timing overlap occurs. As a result, noise is added to the output image, and a desirable slow motion image cannot be obtained.

  Therefore, an object of the present invention is to appropriately obtain a stroboscopic image without changing the light emission timing of a light source that irradiates intermittently such as a stroboscope.

  An electronic endoscope system according to the present invention includes an imaging device, illumination means for intermittently illuminating illumination light, detection means for detecting an illumination light irradiation period and a pixel signal output period of the imaging element, and the imaging element Correction means for performing noise correction processing on an image (herein referred to as an output image) based on the pixel signal output from. As the image pickup device, a charge transfer type image pickup device such as a CCD is applicable. Further, a strobe (electronic flash) or the like can be applied as the illumination means.

  The detection unit determines whether or not the irradiation period and the pixel signal output period overlap, and the correction unit performs noise correction processing when the irradiation period and the pixel signal output period overlap. And

  The noise correction process may be performed on an image portion corresponding to a period in which the irradiation period and the pixel signal output period overlap. Here, the “image portion corresponding to the overlapping period” refers to an area including only a pixel portion where noise is generated (will occur) or the periphery of the pixel portion. For example, when noise partially occurs on one line, only the pixel line of the noise may be corrected, or all the one line may be corrected.

  When the pixel signal is output for each line, the detection unit can detect the overlap period for each line. In this case, correction may be made using at least one pixel data above and below the line where noise occurs.

  The detection means can be provided in the electronic scope, and the detection means preferably detects the illumination light irradiation period by receiving a drive signal of the illumination means via the processor.

  The detection means can detect the pixel signal output period based on a drive signal of an image sensor driving circuit that drives the image sensor.

  The correcting means may be provided in the electronic scope.

  Further, the correction means may sequentially correct the pixel signal for which the overlap period is determined for each line. Alternatively, pixel signals for one field or one frame may be temporarily stored, and correction for the area corresponding to the overlap period may be performed collectively on the entire image.

  In the operation method of the electronic endoscope system according to the present invention, the illumination unit intermittently irradiates the illumination light, and the detection unit detects and detects the illumination light irradiation period and the pixel signal output period of the image sensor. The means determines whether or not the irradiation period and the pixel signal output period overlap. When the irradiation period and the pixel signal output period overlap, the correction means causes noise generated in the output image from the image sensor. Correction processing is performed.

  The program for executing the correction process in the endoscope system of the present invention is a program for executing the correction process in the endoscope system, and the intermittent illumination light irradiation period and the pixel signal output period of the image sensor overlap. A first step of determining whether or not the pixel is present and a second step of performing a noise correction process when the irradiation period and the pixel signal output period overlap.

  According to the present invention, it is possible to appropriately obtain a stroboscopic image without changing the flash emission timing.

It is a block diagram showing the whole electronic endoscope system concerning one embodiment of the present invention. 6 is a timing chart illustrating a case where noise occurs in an output image. It is a figure which shows an example of the output image which noise generate | occur | produced. It is a figure which shows the noise correction sequence in one Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an electronic endoscope system according to an embodiment of the present invention. An electronic endoscope system 10 according to the present embodiment includes an electronic scope 11, a processor 12 to which the electronic scope 11 is detachably connected, a monitor 13 that displays an image from the processor 12, and a light source device 22 (illuminating means). With.

  An imaging element 15 which is a CCD image sensor (for example, an interline transfer type CCD) is provided at the tip of the electronic scope 11. The image sensor 15 is driven and controlled by a signal from a scope controller (detection means / correction means) 16 provided in the connector portion of the electronic scope 11. In the image sensor 15, the subject is imaged through the objective lens 15 </ b> A, and the detected image signal is subjected to correction processing described later in the scope controller 16, and then sent to the pre-stage video signal processing circuit 17 of the processor 12. . The memory 32 is used in correction processing in the scope controller 16.

  In the pre-stage video signal processing circuit 17, the image signal is converted into a digital signal, subjected to predetermined image processing, and sequentially stored in the image memory 18 sequentially. The frame images stored in the image memory 18 are sequentially sent to the subsequent stage video signal processing circuit 19, converted into a video signal of a predetermined standard, for example, and output to an output device such as the monitor 13. The scope controller 16, the front video signal processing circuit 17, the image memory 18, and the rear video signal processing circuit 19 are controlled based on various synchronization signals from the timing controller 20.

  The light source device 22 and the timing controller 20 are controlled by a system controller 24 that controls the entire processor. Shooting of a subject by the image sensor 15 is performed under illumination light supplied from the light source device 22. The illumination light is supplied to the tip of the electronic scope 11 through the light guide 21, and is irradiated from the tip of the electronic scope through the illumination lens 21A.

  When a subject is photographed through the objective lens 15 </ b> A, light enters the light receiving surface of the image sensor 15. Light incident on the light receiving surface of the image sensor 15 is converted into electric charges by a photodiode provided on the light receiving surface. The charges accumulated on the light receiving surface (photodiode) of the image sensor 15 are temporarily transferred to the vertical transfer register, and then output one by one from the image sensor 15 and transmitted to the processor side via the buffer 31. Is done.

  The light source device 22 emits illumination light from a strobe lamp 26 by a lamp power source 25 controlled by the system controller 24. The light source device 22 irradiates the end surface of the light guide 21 with normal light and strobe light, respectively, during normal shooting and during stroboscopic shooting described later. The strobe lamp 26 is, for example, a xenon lamp or an LED. The amount of light output from the strobe lamp 26 is adjusted by a diaphragm 28 driven by a motor 27. The motor 27 is controlled by a driver 29 in response to a signal from the previous video signal processing circuit 17.

  For example, a front panel 30 disposed in front of the processor 12 is connected to the system controller 24. The system controller 24 selects various processes and switches between normal light and strobe light according to the switch operation of the front panel 30.

  When the stroboscope shooting is selected with the switch on the front panel 30, the stroboscopic lamp 26 starts to emit the stroboscope. The pulse emission timing of the strobe lamp 26 is set on the front panel 30. The light emission timing is converted into a strobe drive signal by the system controller 24. The strobe drive signal is transmitted to the lamp power supply 25 and also transmitted to the scope controller 16 via the timing controller 20.

  Stroboscope photography is used, for example, when obtaining a slow motion image of a vocal cord that is vibrating. A slow motion image of the vocal cords is obtained by shifting the light emission period of the strobe light by a predetermined amount with respect to the vibration waveform of the vocal cords. By adjusting the light emission period of the strobe light, a slow motion image having a desired flow of movement can be obtained. The scope controller 16 includes a noise correction processing circuit 16A, and performs noise correction processing on the pixel signal output from the image sensor 15 so that noise caused by strobe emission does not occur in the display image during stroboscope photography.

  The operation at the time of stroboscope photography will be described with reference to FIGS. FIG. 2 is a timing chart showing the relationship between the pixel signal output timing and the strobe light emission timing (illumination light irradiation period) when the pixel signal is output from the image sensor 15 line by line. FIG. 3 is a diagram showing noise generated in the observation image.

  The scope controller 16 outputs a drive pulse for outputting a pixel signal for each line to the image sensor 15 according to the frame period. Accordingly, pixel signals for one line are sequentially output at a predetermined period P.

  On the other hand, in the light source device 22, the illumination light is emitted intermittently (intermittently) from the strobe lamp 26 (see FIG. 2B). The light emission period Q of the strobe light depends on the vibration period of the vocal cords and is longer than the period P of the pixel signal output for one line, and is adjusted so that the phase is gradually shifted to obtain a slow motion image. Has been. The single light emission (irradiation) period S is longer than the pixel signal output time T for one line here.

  As described above, the strobe emission timing and the pixel signal output timing for one line do not coincide with each other, and therefore, both timings may overlap. In FIG. 2, the periods in which the light emission (irradiation) period S and the pixel signal output period T overlap are indicated by D1 and D2. Due to the occurrence of such an overlap period, some noise may occur along the horizontal direction as shown in FIG. The noise N1 is caused by the overlap period D1 (see FIG. 2) in FIG. 2, and the noise N2 is caused by the overlap period D2.

  In this embodiment, in order to prevent the pixel signal output period T and the strobe light emission (irradiation) period S from overlapping and generating noise in the output image, as described in detail below, one field / frame worth Noise correction processing is performed on the pixel signal for the overlap period.

  FIG. 4 is a flowchart of noise correction processing executed in the scope controller 16. The correction procedure will be described with reference to FIG. When the main power supply of the electronic endoscope system 10 is turned on, the noise correction sequence (steps S400 to S405) is activated. Note that this sequence may be configured to operate when stroboscopic imaging is selected.

  In step S401, it is determined whether or not the strobe is emitting light. The start of strobe emission is detected by a drive signal sent from the processor 12. Alternatively, stroboscopic imaging information set in the processor 12 may be acquired and detected. If it is determined that the strobe is not emitting light, the image is not corrected and the sequence ends in step S405.

  If it is determined in step S401 that the strobe is emitting light, the process proceeds to step S403. In step S403, it is sequentially determined for each line whether the pixel signal output period T and the strobe light emission (irradiation) period S overlap. Specifically, the determination is made based on the timing of the strobe light emission drive signal (pulse signal) sent to the light source device 22 and the timing of the drive signal for pixel signal output sent to the image sensor 15.

  If it is determined in step S403 that there is no overlap, noise correction is not performed and the sequence ends. If it is determined that they overlap, noise correction processing is performed in step S404.

  Specifically, the pixel signal of the line in which noise is generated is replaced with the pixel signal for one adjacent upper or lower line output at the previous output timing. In the noise correction processing circuit 16 </ b> A, correction processing is performed based on the pixel signals of the previous and subsequent lines temporarily stored in the memory 32.

  Note that a pixel signal for one field / frame may be temporarily stored in a memory or the like, and after the overlapping period of the entire image is determined, correction processing may be performed on each noise portion. In this case, the noise correction process may use peripheral pixels of the noise portion. For example, correction can be performed using pixel signals for one line on both the upper and lower sides of a line where noise occurs (for example, an average value or specific weighting is performed).

  In addition, the position of the pixel where the noise occurs is determined from the period where the irradiation period S and the pixel signal output period T overlap, and the position where the noise occurs is specified and the pixel signal for one line is not corrected, but the noise is generated. It is also possible to correct only the pixel portion.

  As described above, the present embodiment is configured to perform the correction process by predicting a portion where noise is generated based on the overlap between the pixel signal output period and the strobe light irradiation period. In other words, since the pixel signal output period and the strobe light irradiation period may overlap, the strobe light irradiation period can be freely set regardless of the image signal output period. As a result, the strobe light can be irradiated at an arbitrary phase with respect to the vibration period of the vocal cords, and as a result, a slow motion image of a desired subject can be displayed without disturbance. Also, noise correction affects the image quality of the observed image by correcting whether or not there is an overlap period for each line on the video scope side, that is, correcting before performing image signal processing on the processor side. Can be suppressed. In addition, by sending strobe lighting timing with a relatively long cycle into the scope via the processor, the overlap period of lighting and pixel signal output is detected inside the scope, and the pixel signal output timing with a very short cycle is accurately detected. Therefore, it is possible to reliably perform the overlap determination.

  Note that the image sensor is not limited to a CCD, and noise correction may be applied when the light emission timings of intermittent light sources such as strobes overlap when pixel signals for one line are sequentially output from the image sensor. .

DESCRIPTION OF SYMBOLS 10 Electronic endoscope system 15 Image sensor 16 Scope controller (detection means / correction means)
22 Light source device (illumination means)
S light emission (irradiation) period T pixel signal output period N1, N2 noise D1, D2 overlap period

Claims (7)

An image sensor;
Illuminating means for intermittently illuminating illumination light;
Detecting means for detecting an illumination light irradiation period and a pixel signal output period of the image sensor;
Correction means for performing noise correction processing on the output image from the image sensor,
The detection means determines whether the irradiation period and the pixel signal output period overlap,
The electronic endoscope system according to claim 1, wherein the correction unit performs a noise correction process when the irradiation period and the pixel signal output period overlap.   The electronic endoscope system according to claim 1, wherein the correction unit performs noise correction processing on an image portion corresponding to a period in which the irradiation period and the pixel signal output period overlap. The pixel signal is sequentially output for each line,
3. The noise correction process uses pixel data of at least one of upper and lower lines of a line corresponding to a period corresponding to an overlap period of the irradiation period and the pixel signal output period. The electronic endoscope system according to any one of the above. The detection means is provided in an electronic scope,
4. The electronic device according to claim 1, wherein the detection unit detects an irradiation period of the illumination light by receiving a driving signal of the illumination unit via a processor. Endoscopic system.   The electronic endoscope system according to claim 1, wherein the correction unit is provided in an electronic scope. The illumination means irradiates illumination light intermittently,
The detection means detects the illumination light irradiation period and the pixel signal output period of the image sensor,
The detection means determines whether the irradiation period and the pixel signal output period overlap,
An operation method of an electronic endoscope system, wherein the correction means performs a noise correction process on an image portion corresponding to the overlapping timing when the irradiation period and the pixel signal output period overlap. . A program for executing correction processing in an endoscope system,
A first step for determining whether or not the intermittent illumination light irradiation period and the pixel signal output period of the image sensor overlap;
When the irradiation period and the pixel signal output period overlap, a second step of performing a noise correction process is executed.

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