JP2013090878A - Device for adjusting spectral distribution and endoscopic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the spectral distribution of a light source constant with time.SOLUTION: A beam splitter 31 is arranged on an optical path leading to a light guide 22 from a main light source 21. A light flux from a light source 30 for correction capable of controlling the output of an RGB component is launched into the beam splitter 31, and added to a light flux of the main light source 21. The added light flux is branched off by the beam splitter 31; one is branched off in the direction of the light guide 22; and the other is branched off in a direction perpendicular to the direction of the light guide. The branched light flux is received by a light-receiving sensor 32 via a reflector 35. Tristimulus values of the light flux are detected in the light-receiving sensor 32, and input into a correction circuit 33. In the correction circuit 33. Target tristimulus values read out from memory 34 are compared with the tristimulus values measured by the light-receiving sensor 32, and the output of the RGB component of the light source 30 for correction is adjusted.

Description

  The present invention relates to a spectral distribution adjusting device for correcting a spectral distribution of a light source.

  In general, in an endoscope, light from a light source is guided to a distal end of an insertion portion through a light guide and used as illumination light. For this reason, when the spectral distribution of the light source changes, the color balance of the acquired image changes and adversely affects the diagnosis and the like. For example, in an electronic endoscope apparatus having two light sources that can be switched, the spectral distribution changes due to the switching of the light sources. As such an electronic endoscope, a configuration is known in which correction data for white balance adjustment is prepared in advance for each light source, and white balance processing is corrected according to the switched light source to maintain a constant color balance. (Patent Document 1).

  In addition, as a change in the spectral distribution of illumination light in the endoscope apparatus, the influence of a diaphragm for adjusting the amount of light is also known. That is, in an endoscope, a light beam is incident on the light guide through a general light amount adjusting diaphragm, but the spectral distribution of the light beam is not spatially uniform, and the color temperature is higher at the center of the light beam. Therefore, the spectral distribution of the light incident on the light guide changes depending on the size of the stop, and the color balance of the acquired image is not constant. For such a problem, a configuration is known in which a correction filter is inserted into and removed from the optical path in accordance with the size of the stop to suppress fluctuations in the spectral distribution of light incident on the light guide (Patent Document 2).

JP 2004-121549 A Japanese Patent Laid-Open No. 7-299028

  By the way, in addition to the above-mentioned changes in the spectral distribution of the light source, there are those over time. For example, the spectral distribution of the light source changes due to deterioration over time. In general, halogen lamps, metal halide lamps, xenon lamps, and the like are used as illumination light sources. However, the spectral distribution of these lamps does not stabilize immediately after lighting, and a certain amount of time is required for stabilization. It takes.

  An object of the present invention is to maintain the spectral distribution of the light source constant over time.

  The spectral distribution adjustment device of the present invention receives a correction light source, a light addition optical element for adding correction light from the correction light source to the light beam from the main light source, and a part of the light beam after the correction light is added. A colorimetric means for detecting a parameter representing the spectral distribution of the luminous flux, a memory for holding the target value of the parameter, and the spectral distribution of the luminous flux after the addition of the correction light based on the detected parameter and the target value And control means for controlling the spectral output distribution of the correction light source so as to match.

  The parameter is, for example, a tristimulus value XYZ, and the correction light source is preferably, for example, a RGB component variable light source. The control means, for example, compares the target tristimulus values with the detected tristimulus values X / Y, Z / Y, and adjusts the output of the R component or B component of the light source for correction based on this comparison. Further, for example, the control means calculates each chromaticity value from the target tristimulus value and the detected tristimulus value, and adjusts the output of the RGB components of the light source for correction based on the comparison of the chromaticity values.

  The light adding optical element is a beam splitter, and the light beam received by the colorimetric means is, for example, a light beam branched from the main light beam by the beam splitter. The light beam after the correction light addition is incident on the light guide, and a part of the light beam after the correction light addition is received by the colorimetric means via the branch fiber bundle of the light guide.

  For example, control by the control means is executed continuously only for a predetermined time from when the main light source is turned on until the main light source is stabilized. The target value is preferably a parameter value at the end of previous use.

  An endoscope apparatus according to the present invention includes the spectral distribution adjusting apparatus.

  According to the present invention, the spectral distribution of the light source can be kept constant over time.

It is a block diagram which shows the structure of the electronic endoscope apparatus carrying the light modulation apparatus of 1st Embodiment. It is a block diagram which shows the structure of the spectral distribution adjustment apparatus of 1st Embodiment. It is a flowchart of the whole spectral distribution adjustment process. It is a flowchart of the light source adjustment process for correction | amendment. It is a flowchart of the light source adjustment process for correction | amendment of the modification of 1st Embodiment. It is a block diagram which shows the structure of the electronic endoscope apparatus carrying the light modulation apparatus of 2nd Embodiment. It is a block diagram which shows the structure of the spectral distribution adjustment apparatus of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an endoscope apparatus equipped with the spectral distribution adjusting apparatus according to the first embodiment of the present invention. In FIG. 1, only a part of the configuration relating to the illumination system and the imaging system is shown, and many other configurations are omitted.

  The endoscope apparatus 10 is, for example, an electronic endoscope, and includes a scope 11 having a flexible tubular insertion portion, a processor apparatus 12 to which the scope 11 is detachably connected, and a processor apparatus 12 that is detachably connected. The monitor 13 is mainly configured.

  An imaging element 14 such as a CCD is provided at the distal end of the insertion portion of the scope 11. The driving of the image sensor 14 is controlled based on, for example, a drive signal from an image sensor drive circuit 15 provided in the scope 11, and the image sensor drive circuit 15 receives a clock signal from a timing controller 16 provided in the processor device 12. A drive signal is generated based on the above. A subject image is formed on the imaging surface of the imaging element 14 via the imaging lens 14A, and an image signal of the subject image is generated.

  An image signal output from the image sensor 14 is converted into a digital signal via an analog front end (AFE) 17 in the scope 11, for example, and sent to a pre-stage video signal processing circuit 18 in the processor device 12. In the pre-stage video signal processing circuit 18, predetermined well-known image processing including white balance processing is performed on the video signal and temporarily held in the image memory 19.

  The video signal held in the image memory 19 is output to the subsequent video signal processing circuit 20 at a predetermined timing. In the post-stage video signal processing circuit 20, the video signal is converted into a video signal of a predetermined standard and output to the monitor 13, for example. Note that a series of processing in the upstream signal processing circuit 18, the image memory 19, and the downstream video signal processing circuit 20 is performed based on a clock signal from the timing controller 16.

  On the other hand, the illumination light necessary for photographing the subject image is, for example, from the main light source 21 provided in the processor device 12 to the distal end of the insertion portion of the scope 11 through a light guide (optical fiber) 22 provided in the scope 11. Is transmitted. The light transmitted to the distal end of the insertion portion is irradiated toward the subject via the illumination lens 22A. In the present embodiment, optical elements such as a spectral distribution adjusting device 23, a diaphragm 24, and a condenser lens 25 are arranged on the optical path between the main light source 21 and the incident end of the light guide 22, and the main light source 21 emits light. The emitted light is collected at the incident end of the light guide 22.

  As the main light source 21, for example, a halogen lamp, a metal halide lamp, a xenon lamp, or the like is used.

  FIG. 2 is a block diagram showing the configuration of the spectral distribution adjusting device 23. The spectral distribution adjustment device 23 mainly includes a correction light source 30, a beam splitter (light addition optical element) 31, a light receiving sensor (detection means) 32, a correction circuit (control means) 33, and a memory 34. In addition, although the reflector 35 is further provided in the spectral distribution adjustment apparatus 23 of this embodiment, the reflector 35 can also be omitted.

  The light emitted from the lamp 21A of the main light source 21 is irradiated directly or reflected by the reflecting mirror 21B toward the light guide 22. A beam splitter 31 is disposed on the optical path between the main light source 21 and the light guide 22 so as to cross the light beam. The beam splitter 31 is, for example, a half mirror, and a part of the light beam from the main light source 21 passes through the beam splitter 31 and is guided toward the incident end of the light guide 22. On the other hand, the remaining part is reflected in a predetermined direction, for example, in a direction perpendicular to the light beam from the main light source 21, and guided to the light receiving sensor 32 through the reflector 35.

  Further, the light from the correction light source 30 is emitted toward the beam splitter 31 in a direction that coincides with a predetermined direction in which, for example, a part of the light beam of the main light source 21 is reflected. That is, the light beam from the correction light source 30 is incident on the half mirror of the beam splitter 31 from the surface opposite to the surface on which the light beam from the main light source 21 is incident. A part of the light from the correction light source 30 is added to the light beam from the main light source 21 that is reflected and transmitted through the beam splitter 31, and the light guide 22 passes through the diaphragm 24 and the condenser lens 25 shown in FIG. Is incident on. On the other hand, the remaining part of the light beam from the correction light source 30 is added to the light beam of the main light source 21 that has been transmitted through the beam splitter 31 and reflected by the beam splitter 31, and is guided to the light receiving sensor 32 via the reflector 35. It is burned.

  In the present embodiment, the half mirror has an inclination of 45 ° with respect to the main axis of the light beam from the main light source 21 and the main axis of the light beam from the correction light source 30, but the half mirror in FIG. The angle of the reflecting surface is schematic.

  The light receiving sensor 32 is a sensor that outputs a parameter corresponding to the spectral distribution. In this embodiment, for example, a color sensor that outputs tristimulus values XYZ as a parameter is used. The tristimulus values XYZ output from the light receiving sensor 32 are input to the correction circuit 33. Further, the target value (target tristimulus value) of the parameter is stored in the memory 34, and is compared with the value of the parameter (tristimulus value) output from the light receiving sensor 32 in the correction circuit 33, and based on this. The spectral output of the correction light source 30 is adjusted.

  As the target value, for example, a parameter value (measured tristimulus value) at the end of the previous use is used. The correction light source 30 may be any light source that can control the relative spectral distribution, but in this embodiment, for example, an LED light source equipped with an RGB chip is used.

  Next, the spectral distribution adjustment processing of this embodiment using the spectral distribution adjustment device 23 will be described with reference to the flowcharts of FIGS. 3 and 4 (and FIG. 2).

  The flowchart of FIG. 3 shows the entire spectral distribution adjustment process of this embodiment, and is repeatedly executed at predetermined time intervals when the main light source 21 is turned on. In step S100, the target parameter value corresponding to the target light source color (target spectral distribution), that is, the target tristimulus value (X0, Y0, Z0) in this embodiment is read from the memory 34 by the correction circuit 33. In step S102, tristimulus values (X1, Y1, Z1) detected by the light receiving sensor 32 that is a color sensor are input to the correction circuit 33.

  In step S102, color measurement of light emitted from the main light source 21 is performed by the light receiving sensor 32, and actual tristimulus values are measured. When the correction light source 30 is turned on, the tristimulus value of the light of the main light source 21 plus the light of the correction light source 30 is measured.

  In step S104, adjustment processing of the correction light source 30 is executed based on the target tristimulus values (X0, Y0, Z0) input to the correction circuit 33 and the actually measured tristimulus values (X1, Y1, Z1). Thereafter, the process returns to step S102, and the same process is repeated.

  FIG. 4 is a flowchart showing the processing contents in the correction light source adjustment processing (step S104).

  In the correction light source adjustment process, first, in step S200, it is determined whether or not the ratio X0 / Y0 of the target tristimulus values is different from the ratio X1 / Y1 of the measured tristimulus values X1 and Y1. Is done. When X0 / Y0 = X1 / Y1, it is determined in step S202 whether or not the ratio Z0 / Y0 of the target tristimulus values Z0 / Y0 is different from the actually measured ratio of tristimulus values Z1 and Y1 Z1 / Y1. Is done. When Z0 / Y0 = Z1 / Y1, the ratio of the target tristimulus value (X0, Y0, Z0) and the ratio of the actually measured tristimulus values (X1, Y1, Z1) are equal, and the actually measured spectral distribution is substantially the target. Since this is considered to be equal to the value, this process ends without adjusting the correction light source 30, and after the color measurement is performed in step S102 in FIG. 3, this process is repeated. The determinations in steps S200 and S202 are made based on whether, for example, | X0 / Y0−X1 / Y1 | and | Z0 / Y0−Z1 / Y1 | are within a predetermined value.

  On the other hand, when it is determined in step S200 that X0 / Y0 is not equal to X1 / Y1, it is determined in step S204 whether the value of X1 / Y1 is smaller than X0 / Y0. When the value of X1 / Y1 is larger than X0 / Y0, the ratio of the actually measured X component, that is, the red (R) component is higher than the target value. Therefore, in step S206, the red (R) component of the correction light source 30 The brightness of the light source is reduced by a predetermined value, and this process ends. In the present embodiment, since an LED light source mounted with an RGB chip is used, the value of the R component LED current is reduced by a predetermined amount.

  In step S204, when the value of X1 / Y1 is smaller than X0 / Y0, the ratio of the actually measured X component, that is, the red (R) component is lower than the target value. The brightness of the red (R) component light source is increased by a predetermined value, and this process ends. That is, in this embodiment, the value of the R component LED current is increased by a predetermined amount.

  On the other hand, when it is determined in step S200 that X0 / Y0 is equal to X1 / Y1, and in step S202, it is determined that Z0 / Y0 is not equal to Z1 / Y1, the value of Z1 / Y1 is set to Z0 in step S210. It is determined whether it is smaller than / Y0. When the value of Z1 / Y1 is larger than Z0 / Y0, the ratio of the actually measured Z component, that is, the blue (B) component is higher than the target value. Therefore, in step S212, the blue (B) component of the correction light source 30 is obtained. The brightness of the light source (LED current value of the B component) is reduced by a predetermined value, and this process ends.

  Conversely, when the value of Z1 / Y1 is smaller than Z0 / Y0, the ratio of the actually measured Z component, that is, the blue (B) component, is lower than the target value, so in step S214 the red ( The brightness of the light source of the R component (LED current value of the B component) is increased by a predetermined value, and this process ends.

  As described above, according to the first embodiment, the spectral distribution of the correction light source is controlled in accordance with the change in the spectral distribution of the main light source over time, thereby maintaining the spectral distribution of the light source constant over time. Can do. In particular, in the present embodiment, the present invention can be configured at a lower price by using a colorimeter that outputs tristimulus values to the light receiving sensor.

  In the present embodiment, the spectral distribution is adjusted with reference to the Y value corresponding to green (G) that most affects the brightness, and the brightness of the G component is kept constant.

  FIG. 5 shows a flowchart of a correction light source adjustment process which is a modification of the first embodiment. In the first embodiment, the light source for correction is adjusted based on the ratio of X and Z with reference to Y in the tristimulus values, and the spectral distribution is adjusted. In the modified example, the chromaticity value (x, y) is used. Use to adjust. In the modification, the content of step S104 in FIG. 3 is replaced with those in FIG. 4 to FIG. 5, but the other configurations are the same as those in the first embodiment, and the description thereof is omitted.

  In step S300, the target chromaticity value (x0, y0) and the actually measured chromaticity value (x1, y1) are calculated from the tristimulus values. That is, by substituting the target tristimulus values (X0, Y0, Z0) and the measured tristimulus values (X1, Y1, Z1) into the equations x = X / (X + Y + Z) and y = Y / (X + Y + Z), respectively. A target chromaticity value (x0, y0) and an actually measured chromaticity value (x1, y1) are obtained.

  In steps S302 and S304, it is determined whether x1 is different from x0 and y1 is different from y0. When x1 = x0 and y1 = y0 (for example, | x1-x0 |, | y1-y0 | <predetermined value), the measured chromaticity is equal to the target chromaticity, and therefore the correction light source 30 is adjusted. The process ends without any processing. On the other hand, when it is determined in step S302 that x1 is not equal to x0, it is determined in step S306 whether x1 is larger than x0.

  When x1 is larger than x0, it is considered that the R component of the actual measurement value is relatively larger than the target value. Therefore, in step S308, the light amount (current value) of the R (red) component is reduced by a predetermined amount, or B This process ends after the amount of light (current value) of the (blue) component is increased by a predetermined amount. If it is determined in step S306 that the value of x1 is smaller than x0, the R component of the actual measurement value is considered to be relatively smaller than the target value. Therefore, in step S310, the R (red) component This process ends when the light amount (current value) is increased by a predetermined amount or the light amount (current value) of the B (blue) component is decreased by a predetermined amount.

  On the other hand, when it is determined in step S302 that x1 is equal to x0, and in step S304, it is determined that y1 is not equal to y0, it is determined in step S312 whether y1 is greater than y0. When y1 is larger than y0, it is considered that the G component of the actual measurement value is relatively larger than the target value. Therefore, in step S314, the light amount (current value) of the G (green) component is reduced by a predetermined amount, and this process is performed. Ends. If it is determined in step S312 that the value of y1 is smaller than y0, the G component of the actual measurement value is considered to be relatively smaller than the target value. Therefore, in step S316, the G (green) component This process ends after the light amount (current value) is increased by a predetermined amount.

  As described above, the same effects as those of the first embodiment can be obtained in this modification. In this modification, it is arbitrary whether the R component is increased (reduced) or the B component is decreased (increased). For example, to match the target chromaticity (x0, y0), from the rated current It is also possible to adopt a configuration in which the smaller variable value is selected.

  Next, an electronic endoscope apparatus equipped with the spectral distribution adjusting apparatus according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a block diagram showing the configuration of the electronic endoscope apparatus of the second embodiment. In FIG. 6, only a part of the configuration related to the illumination system and the imaging system is shown, and many other configurations are omitted. Has been.

  In the first embodiment, the light from the main light source 21 or the main light source 21 and the correction light source 30 branched from the main light beam by the beam splitter 31 (see FIG. 2) is detected by the light receiving sensor 32. The second embodiment Then, the illumination light via the light guide 42 is detected by the light receiving sensor 32, and the correction light source is adjusted. In addition, about another structure, it is the same as that of the modification of 1st Embodiment or 1st Embodiment, About the same structure, the description is abbreviate | omitted using the same referential mark.

  As shown in FIG. 6, in the second embodiment, the light guide 42 includes a part of the fiber bundle 42 </ b> A branched in a connector 40 </ b> A used for connection to the processor device 41 of the scope 40, for example. A part of the light incident on the light receiving sensor 32 provided in the light is irradiated. The light receiving sensor 32 is electrically connected to the spectral distribution adjusting device 43 in the processor device 41 via the connector 40A, and constitutes a part of the spectral distribution adjusting device 43 of the second embodiment when the scope is attached.

  FIG. 7 is a block diagram illustrating a configuration of the spectral distribution adjustment device 43 of the second embodiment. In this figure, the diaphragm 24 and the condenser lens 25 are omitted. The arrangement of the main light source 21, the correction light source 30, and the beam splitter 31 as an optical element for adding light is substantially the same as that of the first embodiment, and the light from the main light source 21 via the beam splitter 31 and the correction light source 30 Is condensed at the incident end of the light guide 42 through the condenser lens 25 (FIG. 6).

  As described above, a part of the optical fiber bundle constituting the light guide 42 is branched as the branched fiber bundle 42A in the connector 40A (FIG. 6) of the scope 40, and is incident on the light receiving sensor 32 from the emission end. Part of the light is irradiated. On the other hand, the light guide main body other than the branched fiber bundle 42A is disposed up to the distal end of the insertion portion of the scope 40, and illumination light is irradiated toward the subject S from the distal end.

  The tristimulus values (X1, Y1, Z1) actually measured by the light receiving sensor 32 are input to the correction circuit 33, and are compared with the target tristimulus values (X0, Y0, Z0) in the memory 34 in the first embodiment or Each output of the RGB light of the correction light source 30 is adjusted in the same manner as in the modification.

  As described above, also in the second embodiment, the same effects as those of the first embodiment and its modifications can be obtained. Further, in the second embodiment, since the light passing through the light guide is measured by the light receiving sensor, the change in the spectral distribution due to the deterioration of the light guide can also be corrected.

  In the second embodiment, since the light passing through the light guide is measured, instead of using the parameter value at the end of previous use (actually measured tristimulus value) as the target parameter value (tristimulus value), the serial number of the scope is used. It is also possible to obtain a number and read a target value corresponding to the serial number from the memory.

  In the present embodiment, the tristimulus values XYZ are used as parameters representing the spectral distribution. However, parameters other than the tristimulus values can be used as long as they represent the spectral distribution. In addition to the color meter, for example, a spectrocolorimeter can be used as the light receiving sensor. Further, the correction light source may be other than the light source that can change the RGB components as long as the spectral distribution can be controlled in accordance with the measured parameters.

  In the present embodiment, an electronic endoscope has been described as an example. However, the present invention can also be applied to an endoscope light source device using an image guide, and the light source device is an electronic device independent of a processor device. The present invention can also be applied to an endoscope system. Moreover, it is applicable also to light source devices other than an endoscope.

  In FIG. 2 and FIG. 7, the beam splitter is drawn so as to cross the entire light beam from the main light source, but it is also possible to adopt a configuration that crosses only a part of the center of the light beam. It is also possible to arrange the branch fiber bundle and the light receiving sensor of the second embodiment in the processor device.

  The spectral distribution adjustment process of the present embodiment may be performed only for a predetermined time from the start of lighting until the light source is stabilized. Further, it may be configured to be executed continuously only within a predetermined time, and thereafter adjusted at regular intervals, such as 5 to 10 minutes, in order to correct fluctuation due to deterioration of the light source and light guide with time, In this case, the frequency (interval) at which correction is performed may be adjustable.

  In addition, when the light amount of the correction light source is larger than the light amount of the main light source, a warning (warning sound or warning display) for replacing the main light source may be generated. This is done by monitoring the current value and the like.

DESCRIPTION OF SYMBOLS 10 Electronic endoscope apparatus 11 Scope 12 Processor apparatus 13 Monitor 14 Image pick-up element 21 Main light source 22 Light guide 23 Spectral distribution adjustment apparatus 30 Light source for correction 31 Beam splitter (optical element for light addition)
32 Light receiving sensor 33 Correction circuit 34 Memory

Claims (10)

A correction light source;
A light adding optical element for adding the correction light from the correction light source to the light beam from the main light source;
A colorimetric means for receiving a part of the light flux after the correction light addition and detecting a parameter representing a spectral distribution of the light flux;
A memory for holding a target value of the parameter;
Control means for controlling the spectral output distribution of the light source for correction so that the spectral distribution of the luminous flux after addition of the correction light matches the target value based on the detected parameter and the target value. Spectral distribution adjustment device.   The spectral distribution adjusting apparatus according to claim 1, wherein the parameter is a tristimulus value XYZ.   3. The spectral distribution adjustment apparatus according to claim 2, wherein the correction light source is a RGB component variable light source.   The control means compares the target tristimulus value with the detected tristimulus value X / Y, Z / Y, and adjusts the output of the R component or B component of the light source for correction based on the comparison. The spectral distribution adjusting apparatus according to claim 3.   The control means calculates each chromaticity value from the target tristimulus value and the detected tristimulus value, and adjusts the output of the RGB components of the correction light source based on the comparison of the chromaticity values. The spectral distribution adjusting device according to claim 3.   4. The spectral distribution according to claim 3, wherein the light adding optical element is a beam splitter, and the light beam received by the colorimetric means is a light beam branched from a main light beam by the beam splitter. Adjustment device.   The light beam after the addition of the correction light is incident on a light guide, and a part of the light beam after the addition of the correction light is received by the colorimetric means via a branch fiber bundle of the light guide. 3. The spectral distribution adjusting device according to 3.   4. The spectral distribution adjustment device according to claim 3, wherein the control by the control means is executed continuously only for a predetermined time from when the main light source is turned on until the main light source is stabilized.   The spectral distribution adjustment apparatus according to claim 1, wherein the target value is a parameter value at the end of previous use.   An endoscope apparatus comprising the spectral distribution adjusting apparatus according to claim 1.

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