JP2011019692A - Observation system for medical use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an observation system for medical use, in favorable constitution for measuring photographing distance from a photographing means such as an electronic scope to a subject. <P>SOLUTION: The observation system for medical use includes a plurality of light guide means to uniformly irradiate the subject with illumination light of other than specific wavelength, and unevenly irradiate the subject with illumination light of the specific wavelength, a means to detect reflected light data from the subject, a means to estimate reflected light data corresponding to the illumination light of the specific wavelength based on the reflected light data corresponding to the illumination light of other than the specific wavelength, a means to generate an image of the subject based on these reflected light data, a means to detect brightness distribution of the subject based on the reflected light data corresponding to the illumination light of the specific wavelength, and a means to compute the photographing distance from the photographing means to the subject based on the brightness distribution. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a medical observation system that measures an imaging distance from an electronic scope to a subject, and more specifically, intentionally generates luminance distribution unevenness using existing components for illuminating the subject. The present invention also relates to a medical observation system that measures an imaging distance based on the generated luminance distribution unevenness.

  An electronic scope is generally known as a medical device used when a doctor diagnoses the inside of a body cavity of a patient. A doctor using the electronic scope inserts the insertion portion of the electronic scope into the body cavity and guides the distal end portion provided at the distal end of the insertion portion to the vicinity of the subject. A doctor operates an operation unit of an electronic scope or a video processor as necessary in order to take an image of the inside of a body cavity with a solid-state imaging device such as a CCD (Charge Coupled Device) mounted on the tip. The doctor observes an image in the body cavity obtained as a result of various operations through a monitor, and performs diagnosis and treatment.

  Some recent medical observation systems are equipped with a distance measuring function for measuring an imaging distance from the tip of an electronic scope to a subject in order to assist diagnosis by a doctor. Specific examples of the configuration of the medical observation system having a distance measuring function are described in Patent Documents 1 to 3, for example.

  In the medical observation system described in Patent Document 1, the angle of a pair of rotatable reflectors is controlled, and laser light oscillated from a pair of laser light sources is reflected by each reflector and intersects on a subject. Let The medical observation system measures the imaging distance between the imaging surface of the CCD and the subject based on the angle of each reflector when the two laser beams intersect.

  In the medical observation system described in Patent Document 2, predetermined measurement light is radiated at an oblique angle from the tip of the electronic scope. The imaging distance from the tip of the electronic scope to the subject is calculated based on the spot formation position of the measurement light within the imaging range.

  The medical observation system described in Patent Literature 3 includes two independent illumination optical systems having different imaging distances from the illumination light emission position to the subject. In the medical observation system, an image of a subject illuminated by each illumination optical system is taken independently in synchronization with switching of light emission of the light source. Next, the photographing distance to the subject is measured based on the luminance ratio of the two images corresponding to each photographed illumination optical system.

JP 2005-278980 A Japanese Patent No. 3446272 Specification JP 2002-65581 A

  However, the medical observation system described in Patent Document 1 requires a small and precise drive mechanism that adjusts the angle of the reflector with high accuracy, which complicates the configuration of the tip and increases the manufacturing cost. There is a big problem pointed out.

  In the medical observation system described in Patent Document 2, it is necessary to separately incorporate a dedicated light guide for transmitting measurement light from the proximal end to the distal end of the electronic scope in addition to the light guide for illumination light. Therefore, the diameter of the insertion part of the electronic scope is increased. As the diameter of the insertion portion increases, it becomes difficult to smoothly insert the insertion portion into a minute gap in the patient's body cavity, which is undesirable because the burden on the patient is large.

  In the medical observation system described in Patent Document 3, since a plurality of illumination light sources are required, there is a problem that the burden on the manufacturing cost is large.

  There is a method in which a doctor inserts a measure into a forceps channel of an electronic scope and directly applies it to the subject to measure the distance to the subject. However, since this type of measurement work requires skill, it has been pointed out that accurate measurement is difficult.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a medical observation system having a configuration suitable for measuring an imaging distance from an imaging means such as an electronic scope to a subject. It is to be.

  A medical observation system according to an aspect of the present invention that solves the above problems includes a light source that emits illumination light in a predetermined wavelength range, and a plurality of light guide means that guides the emitted illumination light. The at least one light guide means has wavelength selection means for dimming or shielding only the illumination light of the specific wavelength, and uniformly illuminates the subject with the illumination light other than the specific wavelength, and at the same time the illumination light of the specific wavelength A plurality of light guiding means arranged to illuminate the subject non-uniformly, a detecting means for detecting reflected light data from the illuminated subject, and illumination light other than the detected specific wavelength Based on the first detected reflected light data corresponding to, and using the estimation means for estimating the reflected light data corresponding to the illumination light of the specific wavelength, the first detected reflected data and the estimated reflected light data The subject is illuminated with illumination light in a predetermined wavelength range. A data reproducing unit that reproduces reflected light data in the case of a single illumination, an image generating unit that generates an image of the subject using the reproduced reflected light data, and illumination light of a specific wavelength detected by the detecting unit A luminance distribution detecting means for detecting the luminance distribution of the subject based on the second detected reflected light data corresponding to the imaging distance, and an imaging distance for calculating the imaging distance from the imaging means to the subject based on the detected luminance distribution And a calculation means.

  According to such a configuration, for example, without providing a complicated driving function for distance measurement or a dedicated optical path for measurement light, the photographing distance is measured by using the light distribution by the light guide means that is an existing component. can do. For this reason, an increase in the size of the device and an increase in manufacturing cost associated with the mounting of the distance measuring function can be suitably suppressed. In addition, the shooting distance can be measured in real time without substantially affecting the quality of the color image (eg, image quality, frame rate, etc.).

  Here, the at least one light guide means may include an optical fiber that guides the illumination light and a light distribution lens that distributes the illumination light emitted from the optical fiber to the subject. In such a case, the wavelength selection means is provided as, for example, a fiber Bragg grating formed on an optical fiber or a predetermined filter coating applied to a light distribution lens.

  Here, the luminance distribution detection means divides the second detected reflected light data for one frame detected by the detection means into data corresponding to a plurality of areas obtained by subdividing the one frame, and the divided A configuration may be adopted in which the luminance value corresponding to each divided region is sampled, and the peak value is detected from the sampled luminance values. The shooting distance calculation means may be configured to calculate a ratio between the peak value and a luminance value corresponding to a predetermined divided area, and to calculate a shooting distance based on the calculated ratio.

  The predetermined divided area is, for example, a virtual straight line passing through the center of the divided area corresponding to the peak value and the center of the detection range by the detection means, and sandwiching the center of the detection range. It may be a region located around the detection range on the opposite side of the divided region corresponding to the peak value.

  Here, the shooting distance calculation unit may hold a predetermined function, and calculate the predetermined function using the calculated luminance ratio to obtain the shooting distance.

  In another form, the shooting distance calculating means has a conversion table in which the luminance ratio and the shooting distance are associated with each other, and the shooting distance is obtained by referring to the conversion table using the calculated luminance ratio. Good.

  The medical observation system according to the present invention may further include a luminance setting unit that sets the luminance of the image generated by the image generation unit. In such a case, the shooting distance calculation means holds a predetermined function or conversion table corresponding to each set luminance, and refers to the predetermined function or conversion table using the calculated luminance ratio to determine the shooting distance. Ask.

  The medical observation system according to the present invention includes display information generating means for generating display information representing the photographing distance calculated by the photographing distance calculating means, and display information for outputting the generated display information to a predetermined display device. It is good also as a structure which further has an output means.

  The medical observation system according to the present invention calculates the size of the subject imaged on the imaging means based on the imaging distance calculated by the imaging distance calculation means and the focal length of the objective optical system included in the imaging means. And a size information output unit that outputs information representing the calculated size to a predetermined display device.

  According to the medical observation system of the present invention, for example, light distribution by a light guide means that is an existing component is used without providing a complicated driving function for distance measurement or a dedicated optical path for measurement light. To measure the shooting distance. For this reason, an increase in the size of the device and an increase in manufacturing cost associated with the mounting of the distance measuring function can be suitably suppressed.

1 is an external view of a medical observation system according to an embodiment of the present invention. It is a block diagram showing typically composition of a medical observation system of an embodiment of the present invention. It is a spectral characteristic figure which shows the spectral characteristic of the illumination light which the filter and lamp | ramp of one illumination system radiate | emit. It is a front view of the insertion front-end | tip part of the electronic scope of embodiment of this invention. It is an auxiliary explanatory view for making a relation between a photography range and illumination light quantity distribution understand visually. It is a spectral characteristic figure of the color chip of the solid-state image sensor mounted in the electronic scope of the embodiment of the present invention. It is a block diagram which shows the structure of the signal processing circuit which the processor of embodiment of this invention has. It is a flowchart figure of the process performed in the signal processing circuit which the processor of embodiment of this invention has. It is a subroutine which shows the color restoration process of S2 of FIG. It is a figure for demonstrating the relationship between the luminance distribution of the B component of the subject illuminated only with the illumination light radiated | emitted from one light distribution window, and an imaging distance. It is a figure for demonstrating the relationship between the luminance distribution of the B component of the subject illuminated only with the illumination light radiated | emitted from one light distribution window, and an imaging distance. It is a figure for demonstrating the relationship between the luminance distribution of the B component of the subject illuminated only with the illumination light radiated | emitted from one light distribution window, and an imaging distance. FIG. 13 is a luminance distribution diagram showing a luminance distribution of a B component on a straight line L in each of FIGS. It is a subroutine which shows the distance calculation process of S10 of FIG.

  Hereinafter, a medical observation system according to an embodiment of the present invention will be described with reference to the accompanying drawings. The electronic scope is generally provided with a forceps channel, an air / water supply nozzle, etc., but in this specification or each drawing, this type of component that is not directly related to the features of the present invention is described. The explanation or illustration is omitted for the sake of convenience.

  FIG. 1 is an external view of a medical observation system 1 according to the present embodiment. As shown in FIG. 1, the medical observation system 1 includes an electronic scope 100 that images a patient's body cavity. The electronic scope 100 has an insertion flexible portion 11 that is covered with a flexible tube. Connected to the distal end of the insertion flexible portion 11 is an insertion distal end portion 12 covered with a rigid resin casing. The connecting portion between the insertion flexible portion 11 and the insertion distal end portion 12 is configured to be bent by a remote operation from a hand operating portion 13 connected to the proximal end of the insertion flexible portion 11. As the direction of the insertion distal end 12 changes according to the bending operation by the remote operation, the imaging region by the electronic scope 100 moves.

  As shown in FIG. 1, the medical observation system 1 has a processor 200. The processor 200 is an apparatus that integrally includes a signal processing device that processes a signal from the electronic scope 100 and a light source device that illuminates a body cavity that does not reach natural light via the electronic scope 100. In another embodiment, the signal processing device and the light source device may be configured separately.

  The processor 200 is provided with a connector portion 20 corresponding to the connector 10 provided at the proximal end of the electronic scope 100. The connector unit 20 has a coupling structure corresponding to the connector unit 10 and is configured to electrically and optically connect the electronic scope 100 and the processor 200.

  FIG. 2 is a block diagram schematically showing the configuration of the medical observation system 1. As shown in FIG. 2, the medical observation system 1 includes a monitor 300 connected to a processor 200 via a predetermined cable. In FIG. 1, a monitor 300 that does not have a characteristic configuration according to the present invention is not shown in order to simplify the drawing.

  As illustrated in FIG. 2, the processor 200 includes a system controller 202 and a timing controller 204. The system controller 202 controls each element constituting the medical observation system 1. The timing controller 204 outputs clock pulses for adjusting signal processing timing to various circuits in the medical observation system 1.

  When the power of the processor 200 is turned on, power is supplied from the lamp power source 206 to the lamp 208 and the lamp 208 is turned on to emit white light. As the lamp 208, a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, or a metal halide lamp is suitable. The illumination light emitted from the lamp 208 is collected by the condenser lens 210 and is limited to an appropriate amount of light through the stop 212 and is incident on an incident end of an LCB (light carrying bundle) 102 included in the electronic scope 100. The

  A motor 214 is mechanically connected to the diaphragm 212 via a transmission mechanism such as an arm or a gear (not shown). The motor 214 is a DC motor, for example, and is driven under the drive control of the driver 216. The aperture 212 is operated by the motor 214 to change the opening degree so that the image displayed on the monitor 300 has an appropriate brightness, and limits the amount of illumination light emitted from the lamp 208 according to the opening degree. To do. The appropriate reference for the brightness of the image is changed according to the brightness adjustment operation of the front panel 218 by the operator. Note that the dimming circuit that controls the brightness by controlling the driver 216 is a well-known circuit and is omitted in this specification.

  The illumination light incident on the incident end of the LCB 102 is propagated by repeating total reflection inside the LCB 102. The LCB 102 is branched into two bundles 102A and 102B on the way from the entrance end to the exit end. Illumination light is propagated through the bundle 102 </ b> A or 102 </ b> B with the light quantity divided at the branch point of the LCB 102. The illumination light propagated through each bundle 102A, 102B is emitted from the exit end of each bundle 102A, 102B arranged at the tip of the electronic scope 100.

  The illumination light emitted from the exit end of the bundle 102A illuminates the subject via the light distribution lens 104A and the cover glass 106A. The light distribution lens 104A and the cover glass 106A are not subjected to any filter coating. Therefore, the light distribution lens 104A and the cover glass 106A transmit the entire band of the illumination light emitted from the lamp 208.

  The illumination light emitted from the exit end of the bundle 102B illuminates the subject via the light distribution lens 104B and the cover glass 106B. A predetermined filter coating is applied to either the light distribution lens 104B or the cover glass 106B. FIG. 3 shows the spectral characteristics of the illumination light emitted from the filter and the lamp 208. In FIG. 3, the vertical axis represents the filter transmittance (unit:%) or the intensity of illumination light, and the horizontal axis represents the wavelength (unit: nm). In FIG. 3, the intensity of the illumination light is shown normalized for convenience. As shown in FIG. 3, the filter is a high-pass filter, and cuts light having a short wavelength of about 450 nm or less (most of B light). In another embodiment, a predetermined fiber Bragg grating may be formed in the bundle 102B instead of the filter coating. The illumination light propagating through the bundle 102B causes strong back reflection only for light having a short wavelength of 450 nm or less by a predetermined fiber Bragg grating. Therefore, only light having a wavelength longer than 450 nm is emitted from the emission end of the bundle 102B.

  FIG. 4 is a front view of the insertion tip portion 12. As shown in FIG. 4, two light distribution windows (cover glasses 106 </ b> A and 106 </ b> B in FIG. 4) corresponding to the bundles 102 </ b> A and 102 </ b> B are an imaging system having an objective lens 110 and a solid-state imaging device 112 ( The cover glass 108 that appears on the exterior is shown), and is arranged at symmetrical positions across the center line Y passing through the optical axis. In other words, the two cover glasses 106A and 106B are arranged so that the distances to the imaging system when the insertion tip 12 is viewed from the front are equal. The various optical components included in the electronic scope 100 are R, G, and E (E is an abbreviation of emerald, for example, about 450 nm to 550 nm) (hereinafter, referred to as “RGE light”). The illumination light amounts radiated through the cover glasses 106A and 106B are designed to be equal. Therefore, the subject is subject to the imaging range on condition that the insertion tip 12 and the subject are separated by a predetermined distance or more (in other words, unless the insertion tip 12 is too close to the subject). Illuminated with RGE light having a substantially uniform light amount distribution. As described above, the B light is dimmed (or may be blocked) by a filter or the like only in the optical path on the bundle 102B side. Therefore, the subject is illuminated with a non-uniform light amount distribution within the imaging range with respect to the B light. In addition, the structure which eliminates uneven light distribution by arranging a plurality of light distribution windows is generally known in the field of electronic scope products.

  FIG. 5A to FIG. 5D are supplementary explanatory diagrams for visually understanding the relationship between the imaging range and the illumination light amount distribution. In each figure, the vertical axis represents the amount of illumination light, and the horizontal axis represents the photographing range. Since both are normalized, there is no unit. In each figure, the shooting range is expressed in one dimension for convenience, but is actually two-dimensional. In FIG. 5A, reference numerals EA and EB denote illumination light amount distributions (broken lines) of the E light emitted through the cover glasses 106A and 106B, and reference numeral EL denotes an imaging range in which the illumination light amount distributions EA and EB are combined. The illumination light quantity distribution (solid line) of the entire E light is shown. In FIG. 5B, symbols GA and GB indicate the illumination light amount distribution (broken line) of the G light emitted through the cover glasses 106A and 106B, and symbol GL indicates a photographing range in which the illumination light amount distributions GA and GB are combined. The illumination light quantity distribution (solid line) of the entire G light is shown respectively. Symbols RA and RB in FIG. 5C indicate the illumination light amount distribution (broken line) of the R light emitted through the cover glasses 106A and 106B, and symbol RL indicates a photographing range in which the illumination light amount distributions RA and RB are combined. The illumination light quantity distribution (solid line) of the entire R light is shown. In FIG. 5D, symbols BA and BB indicate the illumination light amount distribution (broken line) of the B light emitted through the cover glasses 106A and 106B, and symbol BL indicates a photographing range in which the illumination light amount distributions BA and BB are combined. The illumination light quantity distribution (solid line) of the entire B light is shown. As is apparent from FIGS. 5A to 5D, the subject is illuminated with RGE light having a substantially uniform light amount distribution and simultaneously with B light having a non-uniform light amount distribution. .

  Reflected light from the subject illuminated by the illumination light is incident on the objective lens 110 through the cover glass 108 and forms an optical image on the light receiving surface of the solid-state imaging device 112 by the power of the objective lens 110.

  The solid-state image sensor 112 is a CCD (for example, 4 color Super HAD CCD manufactured by SONY (registered trademark)) equipped with a four-color filter of RGBE, for example, and an optical image formed by each pixel on the light receiving surface according to the amount of light. Is stored as a charge and converted into an image signal corresponding to each color of R, G, B, and E. The converted image signal is amplified by the preamplifier 114 and input to the driver signal processing circuit 116. Note that each pixel of the solid-state image sensor 112 is composed of four RGBE sub-pixels. The spectral characteristics of the four-color filter are as shown in FIG. In FIG. 6, the vertical axis represents the filter transmittance (unit:%) and the horizontal axis represents the wavelength (unit: mm).

  Based on the clock pulse of the timing controller 204, the driver signal processing circuit 116 drives and controls the solid-state imaging device 112 at a timing synchronized with the frame rate of the video processed on the processor 200 side. The memory 118 stores information unique to the electronic scope 100 (for example, the number and sensitivity of pixels of the solid-state imaging device 112, a compatible rate, or a model number). The driver signal processing circuit 116 accesses the memory 118 and reads information unique to the electronic scope 100.

  The driver signal processing circuit 116 outputs the read unique information to the system controller 202 and the image signal to the signal processing circuit 220, respectively. Between the driver signal processing circuit 116 and the system controller 202 or the signal processing circuit 220, an insulating circuit (not shown) using a photocoupler or the like is disposed. That is, the electronic scope 100 and the processor 200 are electrically insulated.

  The system controller 202 performs various calculations based on the unique information from the driver signal processing circuit 116 and generates a control signal. The system controller 202 uses the generated control signal to control the operation and timing of various circuits in the processor 200 so that processing suitable for the electronic scope connected to the processor 200 is performed. Further, the system controller 202 may be configured to have a table in which a model number of the electronic scope is associated with control information suitable for the electronic scope of the model number. In such a case, the system controller 202 refers to the control information in the correspondence table, and controls the operation and timing of various circuits in the processor 200 so that processing suitable for the electronic scope connected to the processor 200 is performed.

  FIG. 7 is a block diagram showing the configuration of the signal processing circuit 220. As shown in FIG. 7, R, G, and E image signals corresponding to each pixel are input to the B component estimation circuit 222 and the Y / C separation circuit 224 of the signal processing circuit 220. The B component estimation circuit 222 holds three eigenvalue vectors corresponding to R, G, and E components. The B component estimation circuit 222 estimates the B image signal of the pixel using the three eigenvalue vectors and the R, G, and E image signals of each pixel. The B component estimation circuit 222 outputs the estimated B image signal to the Y / C separation circuit 224.

  The B component estimation processing technique by the B component estimation circuit 222 is described in, for example, Reference 1 (Yoichi Miyake, “Introduction to spectral image processing”, The University of Tokyo Press, late February 2006, pages 171 to 173, ISBN 978- 4-13-062141-0) and Reference 2 (Yoichi Miyake, Teruo Kozu, Shuichi Yamataka, “Development of Spectroscopic Endoscope (FICE)”, Image Laboratory, Nihon Kogyo Publishing, April 2006, pages 70-74. ) And the like. Each reference describes that the spectral reflectance of the gastric mucosa and the large intestine mucosa can be estimated by almost 99% using eigenvalue vectors up to the third principal component.

  The Y / C separation circuit 224 separates R, G, B, and E image signals into luminance signals and color signals. The Y / C separation circuit 224 outputs the separated luminance signal to the luminance signal processing circuit 226, and outputs the separated color signal to the color matrix circuit 228, respectively. The luminance signal processing circuit 226 performs various signal processing such as contrast adjustment and blanking adjustment on the luminance signal from the Y / C separation circuit 224. The color matrix circuit 228 performs gain adjustment of the color signal from the Y / C separation circuit 224 and outputs the result to the color difference signal processing circuit 230. The color difference signal processing circuit 230 generates a color difference signal mainly based on the color signal subjected to various signal processing in the color matrix circuit 228. Both the luminance signal and the color difference signal processed by the luminance signal processing circuit 226 and the color difference signal processing circuit 230 are output to the display frame memory 232.

  On the other hand, the B image signal output from the driver signal processing circuit 116 is input to the distance measurement frame memory 252 included in the distance calculation unit 250 as shown in FIG. The ranging frame memory 252 buffers the B image signal in units of frames. The distance measurement frame memory 252 sweeps the buffered B image signal to the distance calculation circuit 254 at the timing of the timing controller 204. The distance calculation circuit 254 calculates an imaging distance D from the insertion tip 12 of the electronic scope 100 to the subject 400 using the B image signal. Details of the distance calculation process will be described later.

  The distance calculation circuit 254 outputs the calculated shooting distance D to the scale creation circuit 256. The scale creation circuit 256 generates information (for example, a character, a scale, etc.) representing the input shooting distance D. The scale creation circuit 256 outputs the generated signal such as character information to the display frame memory 232.

The display frame memory 232 buffers signals such as luminance signals, color difference signals, and character information from the luminance signal processing circuit 226, the color difference signal processing circuit 230, and the scale creation circuit 256 in units of frames. The display frame memory 232 sweeps out each buffered signal at the timing of the timing controller 204. Each signal swept out is received by an NTSC (National Television) by a video signal processing circuit (not shown).
It is converted into a video signal conforming to a predetermined standard such as a System Committee or PAL (Phase Alternating Line) and sequentially output to the monitor 300. The image signal of B is estimated based on the image signal of the subject illuminated with RGE light having a substantially uniform light amount distribution, and the image signal of the subject when illuminated with B light having a substantially uniform light amount distribution Is accurately reproduced. Therefore, the monitor 300 displays a color image that accurately reproduces the subject when illuminated with RGBE light having a substantially uniform light amount distribution. At the same time, character information indicating the shooting distance D is displayed at a predetermined position on the screen.

  FIG. 8 is a flowchart showing processing performed in the signal processing circuit 220. This process is repeatedly performed while the medical observation system 1 is activated, for example. In process step 1, variables i and j are reset to zero. In the following description and drawings in this specification, the processing step is abbreviated as “S”.

In the process of S2, a color restoration process is performed on the B image signal by the B component estimation circuit 222. FIG. 9 is a subroutine showing the color restoration processing in S2 of FIG. As shown in FIG. 8, the B component estimation circuit 222 uses the R, G, E luminance values R of the pixels (i, j) from the driver signal processing circuit 116 based on the R, G, E image signals. (I, j), G (i, j), E (i, j) are calculated (S21). The B component estimation circuit 222 holds three eigenvalue vectors α ₁ , α ₂ , and α ₃ corresponding to the R, G, and E components, and uses the following matrix to determine the B of the pixel (i, j). Is estimated (S22). The B component estimation circuit 222 outputs the B image signal having the estimated luminance value B (i, j) to the Y / C separation circuit 224. The process returns to the process of the flowchart of FIG.

  In the process of S3, the R, G, B, and E image signals of the pixel (i, j) are converted into various circuits such as a Y / C separation circuit 224, a luminance signal processing circuit 226, a color matrix circuit 228, and a color difference signal processing circuit 230. And stored in the corresponding area Img (x, y) in the display frame memory 232. The process of S4 is executed in parallel with the processes of S2 and S3. In the process of S4, the B image signal of the pixel (i, j) from the driver signal processing circuit 116 is stored in the corresponding area Dis (x, y) in the distance measurement frame memory 252.

  In the process of S5, the variable i is incremented by one. In the process of S6, it is determined whether or not the variable i is equal to the maximum value x of the effective address in the horizontal direction. When the processing of S2 to S6 is executed for each pixel in one horizontal line, the variable i becomes the maximum value x (S6: YES), and the processing proceeds to S7. In the process of S7, the variable j is incremented by 1, and the subsequent process target moves to the next horizontal line. In the process of S8, it is determined whether or not the variable j is equal to the maximum value y of the effective addresses in the vertical direction. When an unprocessed horizontal line remains, the processes of S2 to S6 are subsequently executed for each pixel of the remaining horizontal line (S8: NO, S9). When the processes of S2 to S6 are executed for all horizontal lines in the effective area, the variable j becomes the maximum value y (S8: YES), and the process proceeds to S10.

  10 to 12 are diagrams for explaining the luminance distribution of the B component of the subject illuminated by the B illumination light having a nonuniform illumination light amount.

  (A) of each figure of FIGS. 10-12 is a figure which shows typically the relationship between the luminance distribution of B component of a subject, and an imaging range. 10A to 12B, the luminance distribution of the B component of the subject is shown using a contour model. A contour line with a smaller radius of curvature is closer to the center of the illumination light of B, indicating that the subject is illuminated brighter with respect to the B component. 10A to 12B, the symbol O indicates the center of the shooting range, and the symbol L indicates the point with the highest luminance in the shooting range and a straight line passing through the center O.

  10 to 12 and FIG. 13 to be described later show a state in which the illumination light of B emitted from the bundle 102B is completely blocked by a filter for the purpose of clearly explaining the features of the present invention. However, as described above, the B illumination light emitted from the bundle 102B is actually not fully blocked although it is mostly dimmed, and may be emitted from the cover glass 106B. Say that.

  (B) of each figure of FIGS. 10-12 is a figure corresponding to (a) of each figure, Comprising: The imaging distance D from the insertion front-end | tip part 12 of the electronic scope 100 to the test object 400 is shown typically. FIG. In (b) of each figure, in order to simplify the drawing, the components other than the bundles 102A and 102B, the objective lens 110, and the solid-state imaging device 112 among the components of the electronic scope 100 are omitted. Yes.

  10B to 12B, the distance from the main point of the objective lens 110 to the subject 400 is merely shown as the imaging distance D for convenience. Here, the relative positions of various elements of the electronic scope 100 (for example, the principal point of the objective lens 110, the front surface of the insertion tip portion 12, the light receiving surface of the solid-state imaging device 112, etc.) are known. Therefore, the imaging distance D may be defined as a distance from the front surface of the insertion tip 12 to the subject 400, or may be defined as a distance from the light receiving surface of the solid-state imaging device 112 to the subject 400, for example.

  FIG. 13 is a luminance distribution diagram showing the luminance distribution of the B component on the straight line L in FIG. 10 to FIG. In FIG. 13, the vertical axis represents the luminance value, and the horizontal axis represents the coordinates on the straight line L. In FIG. 13, symbol BD1 indicates the luminance distribution of the B component when the shooting distance D is FIG. 10, symbol BD2 indicates the luminance distribution of the B component when the shooting distance D is FIG. 11, and symbol BD3 indicates the shooting distance D. Shows the luminance distribution of the B component in the case of FIG.

  10 to 13, it can be seen that the peak position of the luminance distribution of the B component moves away from the center O of the imaging range as the insertion tip 12 and the subject 400 approach each other. In the distance calculation process of the present embodiment, the shooting distance D is measured using such a characteristic of the luminance distribution.

  FIG. 14 is a subroutine showing the distance calculation process in S10 of FIG. The distance calculation process in FIG. 14 will be described in detail with reference to FIGS. 11A and 13. The distance calculation circuit 254 subdivides each image area in one frame buffered in the distance measurement frame memory 252. Turn into. The distance calculation circuit 254 samples the B luminance value corresponding to each divided image area from the buffered image signal (S101). Specifically, the distance calculation circuit 254 performs histogram processing using the B luminance signal of the pixels belonging to each divided image region in order to sample the B luminance value. Next, using the generated histogram data, an average value of B luminance is calculated for each divided image region to obtain sampling data.

  The distance calculation circuit 254 calculates the luminance value of B, which is a peak, based on the sampling data, and the divided image region R1 corresponding to the luminance value (S102). The distance calculation circuit 254 defines a virtual straight line L that passes through the calculated center of the divided image region R1 and the center O of the shooting range (S103). The distance calculation circuit 254 specifies a divided image region R2 that satisfies a predetermined condition from among the divided image regions on the defined straight line L (S104). The divided image region R2, for example, has a center on the straight line L, and is located around the photographing range on the opposite side of the divided image region R1 across the center O (a position separated by a predetermined pixel from the outermost periphery of the photographing range). Defined as a divided image area. The distance calculation circuit 254 acquires the luminance value of B corresponding to the divided image region R2 from the sampling data (S105). The distance calculation circuit 254 calculates the ratio of the luminance values of the divided image regions R1 and R2 (hereinafter referred to as “luminance ratio”) (S106).

  Here, as described above, the peak position of the luminance distribution of the B component changes in distance from the center O of the shooting range in accordance with the shooting distance D. Accordingly, it can be said that a predetermined relationship is established between the shooting distance D and the luminance ratio. The relationship is expressed by a predetermined function D = f (BR) when the luminance ratio is defined as BR. The distance calculation circuit 254 holds a predetermined function D = f (BR). The distance calculation circuit 254 calculates a predetermined function D = f (BR) using the luminance ratio calculated in the process of S106, and obtains the shooting distance D (S107). In another embodiment, the distance calculation circuit 254 may have a conversion table in which the luminance ratio and the shooting distance D are associated with each other. In such a case, the distance calculation circuit 254 performs the process of S107 using a conversion table instead of the predetermined function D = f (BR).

  The relationship between the shooting distance D and the luminance ratio varies depending on the target brightness set by the luminance adjustment operation on the front panel 218. Therefore, the distance calculation unit 250 may be configured to hold a function or conversion table corresponding to each set luminance (or the opening degree of the diaphragm 212). In such a case, the distance calculation unit 250 can obtain the shooting distance D even during the brightness adjustment operation with reference to a function or conversion table corresponding to the set brightness (or the opening degree of the aperture 212). Further, according to such a configuration, since the shooting distance D is calculated using a function or conversion table suitable for each set brightness (or opening of the aperture 212), an effect of improving the accuracy of the shooting distance D can be obtained. .

  The luminance ratio is a parameter that is relatively unaffected by the subject when the change in hue is large. Therefore, in such a case, the measurement distance error is small and suitable.

  The scale creation circuit 256 generates a signal of information (for example, a character and a scale) representing the shooting distance D calculated by the distance calculation circuit 254 (S108). The scale creation circuit 256 outputs the generated signal such as character information to the display frame memory 232 and adds it to a predetermined image area (S109). The image signal buffered in the display frame memory 232 is output to the monitor 300 at a timing corresponding to the frame rate. As a result, the color image of the subject and the character information indicating the shooting distance D are displayed on the monitor 300 at the same time.

  According to the medical observation system 1 of the present embodiment, the distance calculation process can be performed using an existing bundle without separately providing a complicated driving function for distance measurement and a dedicated optical path for measurement light. . There are no particular parts added to the insertion tip 12 for performing the distance calculation process, and only one light of a specific wavelength is attenuated or shielded by any optical element in the optical path from the branch point of the LCB 102 to the cover glass 106B. It is only necessary to provide an optical action. Therefore, an increase in the size of the insertion tip portion 12 and an increase in manufacturing cost are minimized. In addition, the shooting distance D can be measured in real time without substantially affecting the quality of the color image (for example, image quality, frame rate, etc.). In addition, although the light of a specific wavelength here is B light in this embodiment, it may be light of another wavelength in another embodiment.

  The above is the description of the embodiment of the present invention. The present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the technical idea of the present invention. For example, the electronic scope 100 may have a configuration in which the LCB 102 is branched into three or more bundles. In this case, the electronic scope 100 uniformly illuminates the subject with illumination light from three or more light distribution windows for light other than the specific wavelength. For light of a specific wavelength, the illumination light of the specific wavelength from one or more light distribution windows is dimmed or shielded, and the subject is illuminated with the illumination light of the specific wavelength from at least one light distribution window. Intentionally generate uneven distribution.

  The size of the imaged subject can be calculated using the imaging distance D and the focal length of the objective lens 110 with respect to a specific wavelength. Such a calculation function may be added to the distance calculation circuit 254 and displayed on the monitor 300.

DESCRIPTION OF SYMBOLS 1 Medical system 100 Electronic scope 102A, 102B Bundle 112 Solid-state image sensor 200 Processor 202 System controller 220 Signal processing circuit 250 Distance calculation part 300 Monitor

Claims (10)

A light source that emits illumination light in a predetermined wavelength range;
A plurality of light guide means for guiding the emitted illumination light, wherein at least one light guide means has wavelength selection means for dimming or shielding only the illumination light of a specific wavelength, other than the specific wavelength A plurality of light guiding means arranged to uniformly illuminate the subject with the illumination light and to illuminate the subject non-uniformly with the illumination light of the specific wavelength;
Detecting means for detecting reflected light data from the illuminated subject;
Based on the first detected reflected light data corresponding to the detected illumination light other than the specific wavelength, estimating means for estimating reflected light data corresponding to the illumination light of the specific wavelength;
Data reproduction means for reproducing reflected light data when the subject is uniformly illuminated with illumination light in the predetermined wavelength region using the first detected reflection data and the estimated reflected light data;
Image generating means for generating an image of the subject using the reproduced reflected light data;
Luminance distribution detection means for detecting the luminance distribution of the subject based on second detected reflected light data corresponding to the illumination light of the specific wavelength detected by the detection means;
An imaging distance calculating means for calculating an imaging distance from the imaging means to the subject based on the detected luminance distribution;
A medical observation system characterized by comprising: The at least one light guide means includes
An optical fiber for guiding the illumination light;
A light distribution lens that distributes illumination light emitted from the optical fiber to the subject;
Have
The medical observation system according to claim 1, wherein the wavelength selection means is a fiber Bragg grating formed on the optical fiber or a predetermined filter coating applied to the light distribution lens. The luminance distribution detecting means includes
Dividing the second detected reflected light data for one frame detected by the detecting means into data corresponding to a plurality of regions obtained by subdividing the one frame;
Sampling the luminance value corresponding to each of the divided areas,
A peak value is detected from the sampled luminance values;
The photographing distance calculation means includes
Calculating a ratio between the peak value and a luminance value corresponding to the predetermined divided region;
The medical observation system according to claim 1, wherein the imaging distance is calculated based on the calculated ratio.   The center of the predetermined divided area is on a virtual straight line passing through the center of the divided area corresponding to the peak value and the center of the detection range by the detection means, and the center of the detection range is 4. The medical observation system according to claim 3, wherein the medical observation system is a divided region located around the detection range opposite to the divided region corresponding to the peak value. The photographing distance calculation means includes
Hold a given function,
The medical observation system according to any one of claims 3 and 4, wherein the predetermined function is calculated using the ratio to obtain the imaging distance. A luminance setting means for setting the luminance of the image generated by the image generation means;
6. The medical observation system according to claim 5, wherein the photographing distance calculation means holds the predetermined function corresponding to each set luminance. The photographing distance calculation means includes
A conversion table associating the ratio with the shooting distance;
The medical observation system according to claim 3, wherein the imaging distance is obtained by referring to the conversion table using the ratio. A luminance setting means for setting the luminance of the image generated by the image generation means;
The medical observation system according to claim 7, wherein the photographing distance calculation unit includes the conversion table corresponding to the set luminance. Display information generating means for generating display information representing the shooting distance calculated by the shooting distance calculating means;
Display information output means for outputting the generated display information to a predetermined display device;
The medical observation system according to any one of claims 1 to 8, further comprising: A size calculation means for calculating the size of the subject imaged on the imaging means based on the imaging distance calculated by the imaging distance calculation means and a focal length of an objective optical system included in the imaging means;
Size information output means for outputting information representing the calculated size to a predetermined display device;
The medical observation system according to any one of claims 1 to 9, further comprising:

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