JP2011019691A - Observation system for medical treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an observation system for medical treatment with a structure suitable for measuring the photographing distance between an image pickup means like an electronic scope, etc. and a subject. <P>SOLUTION: An observation system for medical treatment includes a photographing means to photograph the subject, a lighting means to unevenly illuminate the subject in the photographing range of the photographing means, a brightness distribution detector to detect the brightness distribution on the illumined subject in the photographing range, and a photographing distance calculation means to calculate the photographing distance between the photographing means and the subject based on the brightness distribution detected. <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 problem includes an imaging unit that images a subject, an illumination unit that illuminates the subject non-uniformly within an imaging range of the imaging unit, and the illumination A luminance distribution detecting unit that detects a luminance distribution within the imaging range of the subject, and an imaging distance calculating unit that calculates an imaging distance from the imaging unit to the subject based on the detected luminance distribution. It is a featured system.

  According to such a configuration, for example, an imaging distance is measured using light distribution by an illuminating unit that is an existing component without providing a complicated driving function for distance measurement or a dedicated optical path for measurement light. be able to. 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.

  The medical observation system according to the present invention may further include a light distribution switching unit that switches the light distribution by the illumination unit within the imaging range to either a uniform light distribution or a non-uniform light distribution.

  The illumination means has a light source that emits illumination light and a plurality of light guides that guide the emitted illumination light, and within the imaging range when illumination light is emitted from the plurality of light guides It may be configured to uniformly illuminate the subject. The light distribution switching unit may include an illumination light radiation switching unit that switches radiation or shielding of illumination light from one or more light guides excluding at least one light guide. Specific examples of the illumination light radiation switching means include a liquid crystal shutter and a mechanical shutter.

  Another form of illuminating means may have a plurality of light sources and be configured to uniformly illuminate the subject within the imaging range when illumination light is emitted from the plurality of light sources. . The light distribution switching unit may include a light source control unit that turns off one or more light sources excluding at least one light source.

  The medical observation system according to the present invention may further include a light distribution switching operation means for operating light distribution switching by the light distribution switching means. In conjunction with the switching operation to the non-uniform light distribution by the light distribution switching operation means, the luminance distribution detection processing by the luminance distribution detection means and the photographing distance calculation processing by the photographing distance calculation means are executed. Also good.

  Here, the luminance distribution detection means divides one frame imaged by the imaging means into a plurality of areas, samples the luminance values corresponding to the divided areas, and determines from the sampled luminance values. It is good also as a structure which detects a peak value. 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, the center of the area on a virtual straight line passing through the center of the divided area corresponding to the peak value and the center of the shooting range, and the peak value across the center of the shooting range. It is good also as an area | region located in the periphery of this imaging | photography range on the opposite side to this divided area corresponding to.

  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 an image captured by the imaging 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, without using a complicated driving function for distance measurement or a dedicated optical path for measurement light, the light distribution by the illumination means that is an existing component is used. The shooting distance can be measured. 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 front view of the insertion front-end | tip part of the electronic scope of embodiment of this invention. It is a flowchart figure which shows the distance calculation process which the distance calculation part of a processor performs in embodiment of this invention. It is a figure for demonstrating the relationship between the luminance distribution 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 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 subject illuminated only with the illumination light radiated | emitted from one light distribution window, and an imaging distance. FIG. 8 is a luminance distribution diagram showing a luminance distribution on a straight line L in each of FIGS. It is a figure which shows typically the structure of the insertion front-end | tip part of the electronic scope of another embodiment.

  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 illumination light emitted from the exit end of the bundle 102B illuminates the subject via the liquid crystal shutter 120, the light distribution lens 104B, and the cover glass 106B. The liquid crystal shutter 120 switches the orientation of the liquid crystal according to an operation by a hand switch provided on the hand operation unit 13 or a panel switch provided on the front panel 218, and transmits or blocks illumination light. Specifically, the liquid crystal shutter 120 transmits illumination light while the hand switch or the panel switch is turned off. While the hand switch or panel switch is on, the illumination light is shielded. The hand switch or the panel switch is initially turned off.

  FIG. 3 is a front view of the insertion tip portion 12. As shown in FIG. 3, two light distribution windows (cover glasses 106 </ b> A and 106 </ b> B in FIG. 3) corresponding to the bundles 102 </ b> A and 102 </ b> B have an imaging system (in FIG. 3, 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. In addition, various optical components included in the electronic scope 100 are designed so that the illumination light amounts emitted through the cover glasses 106A and 106B are equal when the liquid crystal shutter 120 is in a light transmitting state. When illumination light is emitted through the two cover glasses 106A and 106B, the subject is subject to the condition that the insertion tip 12 and the subject are separated by a predetermined distance or more (according to another expression, the insertion Unless the tip 12 is too close to the subject), illumination is performed with a substantially uniform light amount distribution within the imaging range. 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.

  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 imaging device 112 is, for example, a single-plate color CCD having a Bayer-type pixel arrangement, accumulates an optical image formed by each pixel on the light receiving surface as a charge corresponding to the amount of light, and each color of R, G, B Is converted into an image signal corresponding to. The converted image signal is amplified by the preamplifier 114 and input to the driver signal processing circuit 116.

  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.

  The signal processing circuit 220 subjects the image signal from the driver signal processing circuit 116 to A / D conversion by performing predetermined signal processing such as clamping, knee, γ correction, interpolation processing, AGC (Auto Gain Control), etc. Buffering. The signal processing circuit 220 sweeps out the buffered frame-unit image signal at the timing of the timing controller 204, and converts it into a video signal conforming to a predetermined standard such as NTSC (National Television System Committee) or PAL (Phase Alternating Line). The data is converted and sequentially output to the monitor 300. Thereby, a color image of the subject is displayed on the monitor 300.

  The signal processing circuit 220 includes a distance calculation unit 250 that executes a distance calculation process in conjunction with turning on the hand switch or the panel switch. FIG. 4 is a flowchart showing distance calculation processing executed by the distance calculation unit 250. The distance calculation process is repeatedly executed while the hand switch or the panel switch is on. When the hand switch or the panel switch is turned off, the distance calculation process is forcibly terminated. In the following description and drawings in this specification, the processing step is abbreviated as “S”.

  When the hand switch or the panel switch is turned on and the orientation of the liquid crystal shutter 120 is switched, the illumination light emitted from the exit end of the bundle 102B is blocked by the liquid crystal shutter 120. Therefore, the subject is illuminated only with illumination light emitted through the cover glass 106A. The light quantity distribution at this time becomes non-uniform within the photographing range.

  5-8 is a figure for demonstrating the luminance distribution of the subject illuminated only with the illumination light radiated | emitted via the cover glass 106A.

  (A) of each figure of FIGS. 5-7 is a figure which shows typically the relationship between the luminance distribution of a subject, and an imaging range. In each of FIGS. 5A to 7A, the luminance distribution 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, indicating that the subject is illuminated brighter. 5A to 7A, the symbol O indicates the center of the shooting range, and the symbol L indicates the point having the highest luminance in the shooting range and a straight line passing through the center O.

  (B) of each figure of FIGS. 5-7 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 subject 400 is typically shown. FIG. In each figure (b), in order to simplify the drawing, components other than the bundles 102A and 102B, the objective lens 110, the solid-state imaging device 112, and the liquid crystal shutter 120 among the components of the electronic scope 100 are shown. Is omitted.

  5B to 7B, the distance from the principal 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. 8 is a luminance distribution diagram showing the luminance distribution on the straight line L in (a) of each of FIGS. In FIG. 8, the vertical axis indicates the luminance value, and the horizontal axis indicates the coordinates on the straight line L. In FIG. 8, reference numeral BD1 indicates the luminance distribution when the shooting distance D is FIG. 5, reference numeral BD2 indicates the luminance distribution when the shooting distance D is FIG. 6, and reference numeral BD3 indicates that the shooting distance D is FIG. The luminance distribution of each is shown.

  5 to 8, it can be seen that the peak position of the luminance distribution is further away from the center O of the imaging range as the insertion tip portion 12 and the subject 400 are closer to 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.

  The distance calculation process in FIG. 4 will be specifically described with reference to FIGS. 6A and 8. The distance calculation unit 250 subdivides each image area in one frame. The distance calculation unit 250 samples the luminance value corresponding to each divided image area from the buffered image signal (S101). Specifically, the distance calculation unit 250 performs histogram processing using luminance signals of pixels belonging to each divided image region in order to sample the luminance value. Next, using the generated histogram data, an average value of luminance is calculated for each divided image region to obtain sampling data.

  The distance calculation unit 250 calculates the peak luminance value based on the sampling data and the divided image region R1 corresponding to the luminance value (S102). The distance calculation unit 250 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 unit 250 identifies 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 unit 250 acquires a luminance value corresponding to the divided image region R2 from the sampling data (S105). The distance calculation unit 250 calculates a ratio of luminance values of the divided image regions R1 and R2 (hereinafter referred to as “luminance ratio”) (S106).

  Here, as described above, the distance between the peak position of the luminance distribution and the center O of the shooting range changes according to 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 unit 250 holds a predetermined function D = f (BR). The distance calculation unit 250 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 unit 250 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 unit 250 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. . In calculating the shooting distance D, the luminance values of all the colors may be used, or only the luminance value of a specific color (for example, the R luminance value) may be used.

  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.

  Next, the distance calculation unit 250 generates a signal of information (for example, character, scale, etc.) representing the calculated shooting distance D (S108). The distance calculation unit 250 adds the generated signal such as character information to the image signal output from the signal processing circuit 220 (S109). Thereby, the character information indicating the imaging distance D and the like are displayed on the monitor 300 together with the color image of the subject.

  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. . The liquid crystal shutter 120 is the only component added to the insertion tip 12 for performing the distance calculation process, and the increase in the size of the insertion tip 12 and the increase in manufacturing cost are minimized.

  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 during normal observation. When performing the distance calculation process, the illumination light from one or more light distribution windows is shielded while the subject is illuminated by the illumination light from at least one light distribution window to intentionally generate uneven brightness distribution. To do.

  The electronic scope 100 may have a mechanical shutter as an alternative to the liquid crystal shutter 120.

  The size of the imaged subject can be calculated using the imaging distance D and the focal length of the objective lens 110. Such a calculation function may be added to the distance calculation unit 250 and displayed on the monitor 300.

  FIGS. 9A and 9B are diagrams schematically illustrating a configuration of the insertion tip portion 12 of the electronic scope 100 according to another embodiment. The electronic scope 100 according to another embodiment includes two LEDs (Light Emitting Diodes) 130A and 130B in place of the LCB 102 (including the bundles 102A and 102B). While the hand switch or the panel switch is turned off, as shown in FIG. 9A, the two LEDs 130A and 130B are lit to illuminate the subject with almost uniform illuminance. While the hand switch or the panel switch is on, as shown in FIG. 9B, only the LED 130A is turned off to illuminate the subject unevenly. In another embodiment, the photographing process D can also be measured by intentionally generating luminance distribution unevenness.

DESCRIPTION OF SYMBOLS 1 Medical system 100 Electronic scope 102A, 102B Bundle 112 Solid-state image sensor 120 Liquid crystal shutter 200 Processor 202 System controller 220 Signal processing circuit 250 Distance calculation part 300 Monitor

Claims (14)

An imaging means for imaging the subject;
Illuminating means for illuminating the subject non-uniformly within an imaging range of the imaging means;
A luminance distribution detecting means for detecting a luminance distribution within the imaging range of the illuminated subject;
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 medical observation system according to claim 1, further comprising a light distribution switching unit that switches light distribution by the illumination unit within the imaging range to either uniform or non-uniform light distribution. The illumination means includes
A light source that emits illumination light;
A plurality of light guides for guiding the emitted illumination light;
Have
Illuminating the subject uniformly within the imaging range when the illumination light is emitted from the plurality of light guides,
The light distribution switching means is
3. The medical observation system according to claim 2, further comprising illumination light radiation switching means for switching radiation or shielding of illumination light from the light guide paths that is one or more and less than the plurality.   The medical observation system according to claim 3, wherein the illumination light radiation switching means is a liquid crystal shutter or a mechanical shutter. The illumination means includes
Having multiple light sources,
Illuminating the subject uniformly within the imaging range when the illumination light is emitted from the plurality of light sources,
The light distribution switching means is
The medical observation system according to claim 2, further comprising a light source control unit that turns off one or more of the light sources less than the plurality. A light distribution switching operation means for operating light distribution switching by the light distribution switching means;
In conjunction with the switching operation to the non-uniform light distribution by the light distribution switching operation means, the luminance distribution detection processing by the luminance distribution detection means and the photographing distance calculation processing by the photographing distance calculation means are executed. The medical observation system according to any one of claims 2 to 5, wherein the medical observation system is characterized. The luminance distribution detecting means includes
Dividing one frame photographed by the photographing means into a plurality of regions;
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 any one of claims 1 to 6, wherein the photographing 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 imaging area and the center of the imaging area corresponding to the peak value, and sandwiching the center of the imaging area. The medical observation system according to claim 7, wherein the medical observation system is a divided region located around the imaging range on the opposite side to the divided region corresponding to a peak value. The photographing distance calculation means includes
Hold a given function,
The medical observation system according to claim 7, wherein the predetermined function is calculated using the ratio to obtain the imaging distance. A brightness setting means for setting the brightness of an image photographed by the photographing means;
The medical observation system according to claim 9, wherein the photographing distance calculation unit 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 7, wherein the imaging distance is obtained by referring to the conversion table using the ratio. A brightness setting means for setting the brightness of an image photographed by the photographing means;
The medical observation system according to claim 11, 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 12, 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 13, further comprising:

Images