JP2018201812A - Scanning endoscope apparatus and image generation method - Google Patents

Abstract

To enable the generation of an enlarged observation image with deterioration of image quality suppressed.SOLUTION: A scanning endoscope apparatus according to the present invention comprises: a light guiding section for guiding illumination light to illuminate a subject and emitting the light from an emission end; a scan unit for varying, by shaking the emission end at a predetermined shaking variation rate, the projection site onto which the illumination light emitted to the subject is projected; a light detection unit for detecting returned light of the illumination light emitted to the subject and generating signals according to the returned light; a storage unit for storing enlargement interpolation parameters determined based on projection sites of the illumination light when the scan unit shakes the emission end at a shaking variation rate greater than the predetermined shaking variation rate; and an image generation unit for generating an enlarged observation image based on the signals generated by the light detection unit and the enlargement interpolation parameters stored in the storage unit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a scanning endoscope apparatus that generates an image by scanning a subject, and an image generation method that is executed in the scanning endoscope apparatus.

  Conventionally, as an endoscope apparatus used for endoscopy in the medical field or the like, an endoscope apparatus (see, for example, Patent Document 1) having an imaging element in an insertion portion inserted into a subject, 2. Description of the Related Art A scanning endoscope apparatus or the like that does not have an image sensor in an insertion portion that is inserted into the camera is known.

  In general, a scanning endoscope apparatus scans a subject along a preset scanning path by swinging a tip of an illumination fiber (optical fiber) that guides illumination light emitted from a light source. The return light from the subject is received by a light receiving fiber (optical fiber) disposed around the illumination fiber, and an observation image of the subject is generated based on the return light received by the light receiving fiber. It is configured.

JP 2012-222658 A

  In the case of generating an enlarged observation image of a subject, in a conventional scanning endoscope apparatus, after generating the observation image of the subject as described above, an enlarged image of the observation image (for example, a part of the observation image) is generated. By executing the processing, the enlarged observation image is generated. Therefore, there has been a problem that the image quality of the enlarged observation image to be generated is deteriorated.

  In view of the above situation, an object of the present invention is to provide a scanning endoscope apparatus and an image generation method capable of generating a magnified observation image in which image quality deterioration is suppressed.

  According to a first aspect of the present invention, a light guide unit that guides illumination light for illuminating a subject and emits the light from an exit end, and the exit end is swung at a predetermined swing change rate. A scanning unit that displaces an irradiation position of the illumination light emitted to the subject; a light detection unit that detects return light of the illumination light emitted to the subject and generates a signal corresponding to the return light; and the scanning A storage unit for storing an interpolation parameter for enlargement determined based on the irradiation position of the illumination light when the unit swings the emission end at a swing change rate larger than the predetermined swing change rate; An image generating unit that generates an enlarged observation image based on the signal generated by the light detection unit and the interpolation parameter for enlargement stored in the storage unit.

  According to a second aspect of the present invention, in the first aspect, the irradiation position of the illumination light when the scanning unit swings the emission end portion at a swing change rate larger than the predetermined swing change rate. And an interpolation parameter generation unit that generates the enlargement interpolation parameter based on the calculation result.

  According to a third aspect of the present invention, in the first aspect, the storage unit further irradiates the illumination light when the scanning unit swings the emission end at the predetermined swing change rate. An equal magnification interpolation parameter determined based on a position is stored, and the image generation unit is further based on the signal generated by the light detection unit and the equal magnification interpolation parameter stored in the storage unit. To generate the same magnification observation image.

  According to a fourth aspect of the present invention, in the third aspect, the irradiation position of the illumination light is calculated when the scanning unit swings the emission end portion at the predetermined swing change rate, and the calculation result The equalization interpolation parameter is generated based on the above, and the irradiation position of the illumination light when the scanning unit swings the emission end portion with a swing change rate larger than the predetermined swing change rate. An interpolation parameter generation unit that calculates and generates the enlargement interpolation parameter based on the calculation result

  According to a fifth aspect of the present invention, there is provided an image generation method executed in a scanning endoscope apparatus, wherein the illumination light is emitted from an emission end of a light guide that guides illumination light for illuminating a subject. Illuminating, displacing the irradiation position of the illumination light emitted to the subject by oscillating the emission end with a predetermined rate of change of oscillation, detecting return light of the illumination light emitted to the subject, A signal corresponding to the return light is generated, and based on the generated signal and the irradiation position of the illumination light when the emission end is swung at a swing change rate larger than the predetermined swing change rate. An enlarged observation image is generated based on the enlargement interpolation parameter determined in this manner.

  According to the present invention, it is possible to provide a scanning endoscope apparatus and an image generation method capable of generating a magnified observation image in which image quality deterioration is suppressed.

It is a figure which shows the structural example of the scanning endoscope apparatus which concerns on one embodiment. It is sectional drawing explaining the structural example of an actuator part. It is a figure which shows an example of the signal waveform of the drive signal supplied to an actuator part. 6 is a diagram illustrating an example of a spiral scanning path from a center point A to an outermost point B. FIG. 5 is a diagram illustrating an example of a spiral scanning path from an outermost point B to a center point A. FIG. It is a flowchart which shows the flow of an interpolation parameter production | generation process. It is a figure which shows typically the process process which calculates the irradiation position of the illumination light for every sampling time. It is a figure which shows typically the process of matching eight irradiation positions for interpolation with respect to each pixel area | region on an image area | region (image drawing area). It is a figure which shows typically the process process which matches the sampling time and weighting coefficient of eight irradiation positions for interpolation with respect to each pixel area on an image area (image drawing area). FIG. 4 is a diagram illustrating an example of a signal waveform of a drive signal when an amplitude change rate of the drive signal of the signal waveform illustrated in FIG. 3 is enlarged. It is a flowchart which shows the flow of the observation image generation process for 1 frame. It is a figure which shows typically the process process which produces | generates the 1x observation image for 1 frame. It is a figure which shows typically the expansion observation image generation process of the past, and the expansion observation generation process which concerns on this embodiment. It is a figure which shows an example of the time change of the rocking | fluctuation width when rocking | fluctuation of the radiation | emission end part of the illumination fiber is controlled by the drive signal based on a sine wave. It is a figure which shows an example of the locus | trajectory of a scanning line (trajectory of the irradiation position of illumination light) when rocking | fluctuation of the output end part of the illumination fiber 12 is controlled by the drive signal based on a sine wave.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the configuration of a scanning endoscope apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. This scanning endoscope apparatus is used for endoscopy in the medical field.

  FIG. 1 is a diagram illustrating a configuration example of a scanning endoscope apparatus according to the present embodiment. FIG. 2 is a cross-sectional view illustrating a configuration example of the actuator unit. FIG. 3 is a diagram illustrating an example of a signal waveform of a drive signal supplied to the actuator unit. FIG. 4 is a diagram illustrating an example of a spiral scanning path from the center point A to the outermost point B. FIG. FIG. 5 is a diagram illustrating an example of a spiral scanning path from the outermost point B to the center point A. FIG.

  As shown in FIG. 1, a scanning endoscope apparatus 1 includes a scanning endoscope 2 that is inserted into a body cavity of a subject, a main body apparatus 3 that can connect the endoscope 2, and a main body apparatus. 3 and a display device 4 connected to 3 and an input device 5 capable of inputting information and giving instructions to the main body device 3.

The endoscope 2 has an insertion portion 11 formed with an elongated shape that can be inserted into a body cavity of a subject.
A connector portion 61 for detachably connecting the endoscope 2 to the connector receiving portion 62 of the main body device 3 is provided at the proximal end portion of the insertion portion 11.

  Although not shown in the drawings, an electrical connector device for electrically connecting the endoscope 2 and the main body device 3 is provided inside the connector portion 61 and the connector receiving portion 62. Although not shown, an optical connector device for optically connecting the endoscope 2 and the main body device 3 is provided inside the connector portion 61 and the connector receiving portion 62.

  An illumination fiber 12 that is an optical fiber that guides the illumination light supplied from the light source unit 21 of the main body device 3 to the illumination optical system 14 in a portion from the proximal end portion to the distal end portion inside the insertion portion 11, and A light receiving fiber 13 having one or more optical fibers for receiving return light from the subject and guiding it to the detection unit 23 of the main body device 3 is inserted.

  The incident end including the light incident surface of the illumination fiber 12 is disposed in a multiplexer 32 provided inside the main body device 3. Further, the emission end portion including the light emission surface of the illumination fiber 12 is disposed in the vicinity of the light incident surface of the lens 14 a provided at the distal end portion of the insertion portion 11.

  The incident end including the light incident surface of the light receiving fiber 13 is fixedly disposed around the light emitting surface of the lens 14 b at the distal end surface of the distal end portion of the insertion portion 11. Further, the emission end portion including the light emission surface of the light receiving fiber 13 is arranged in a duplexer 36 provided inside the main body device 3.

The illumination optical system 14 includes a lens 14a that receives illumination light that has passed through the light exit surface of the illumination fiber 12, and a lens 14b that emits illumination light that has passed through the lens 14a to a subject.
An actuator unit 15 that is driven based on a drive signal supplied from the driver unit 22 of the main unit 3 is provided in the middle of the illumination fiber 12 on the distal end side of the insertion unit 11.

The illumination fiber 12 and the actuator unit 15 are arranged so as to have, for example, the positional relationship shown in FIG. 2 in a cross section perpendicular to the longitudinal axis direction of the insertion unit 11.
As shown in FIG. 2, a ferrule 41 as a joining member is disposed between the illumination fiber 12 and the actuator unit 15. Specifically, the ferrule 41 is made of, for example, zirconia (ceramic) or nickel.

  As shown in FIG. 2, the ferrule 41 is formed in a quadrangular prism shape, and side surfaces 42 a and 42 c that are perpendicular to the X-axis direction, which is a first axial direction orthogonal to the longitudinal axis direction of the insertion portion 11, Side surfaces 42b and 42d perpendicular to the Y-axis direction, which is the second axial direction perpendicular to the longitudinal axis direction of the insertion portion 11, are included. The illumination fiber 12 is fixedly arranged at the center of the ferrule 41. The ferrule 41 may be formed as a shape other than the quadrangular column as long as it has a column shape.

  As shown in FIG. 2, the actuator section 15 includes a piezoelectric element 15a disposed along the side surface 42a, a piezoelectric element 15b disposed along the side surface 42b, and a piezoelectric element 15c disposed along the side surface 42c. , And a piezoelectric element 15d disposed along the side surface 42d.

The piezoelectric elements 15 a, 15 b, 15 c, and 15 d are configured to be polarized in individually set polarization directions and expand and contract in accordance with a drive signal supplied from the main body device 3.
That is, the endoscope 2 is configured to scan the subject with illumination light emitted from the light source unit 21 of the main body device 3 and to receive the return light from the subject through the light receiving fiber 13.

  Inside the insertion unit 11, a memory 16 is provided in which endoscope information including various information related to the endoscope 2 is stored. The endoscope information stored in the memory 16 is read out by the controller 25 of the main body device 3 when the connector portion 61 of the endoscope 2 and the connector receiving portion 62 of the main body device 3 are connected. In the present embodiment, the endoscope information includes endoscope driving information. The endoscope drive information includes information related to the drive frequency and amplitude coefficient for determining the signal waveform of the drive signal supplied to the actuator unit 15, and a sampling period for determining the detection timing by the detection unit 23 described later ( Sampling frequency) and information on the number of samples per period.

The main body device 3 includes a light source unit 21, a driver unit 22, a detection unit 23, a memory 24, and a controller 25.
The light source unit 21 includes light sources 31a, 31b, and 31c, and a multiplexer 32.

  The light source 31 a includes, for example, a laser light source and emits light in a red wavelength band (hereinafter also referred to as R light) to the multiplexer 32 when light is emitted under the control of the controller 25. The light source 31 b includes, for example, a laser light source and emits light in a green wavelength band (hereinafter also referred to as G light) to the multiplexer 32 when light is emitted under the control of the controller 25. The light source 31 c includes, for example, a laser light source and emits light in a blue wavelength band (hereinafter also referred to as B light) to the multiplexer 32 when light is emitted under the control of the controller 25.

  The multiplexer 32 multiplexes the R light emitted from the light source 31a, the G light emitted from the light source 31b, and the B light emitted from the light source 31c onto the light incident surface of the illumination fiber 12. Supply.

The driver unit 22 includes a signal generator 33, D / A converters 34a and 34b, and an amplifier 35.
Based on the control of the controller 25, the signal generator 33 is a predetermined drive signal as shown by a broken line in FIG. 3, for example, as a first drive signal for swinging the emission end of the illumination fiber 12 in the X-axis direction. A signal having a signal waveform obtained by performing the above modulation on a sine wave is generated and output to the D / A converter 34a. Further, the signal generator 33 is, for example, indicated by a one-dot chain line in FIG. 3 as a second drive signal for swinging the emission end of the illumination fiber 12 in the Y-axis direction based on the control of the controller 25. A signal having a signal waveform in which the phase of the first drive signal is shifted by 90 ° is generated and output to the D / A converter 34b.

  The D / A converter 34 a converts the digital first drive signal output from the signal generator 33 into an analog first drive signal and outputs the analog first drive signal to the amplifier 35. The D / A converter 34 b converts the digital second drive signal output from the signal generator 33 into an analog second drive signal and outputs the analog second drive signal to the amplifier 35.

The amplifier 35 amplifies the first and second drive signals output from the D / A converters 34 a and 34 b and outputs the amplified signals to the actuator unit 15.
Here, for example, a first drive signal having a signal waveform as shown by a broken line in FIG. 3 is supplied to the piezoelectric elements 15a and 15c of the actuator unit 15, and a signal waveform as shown by a one-dot chain line in FIG. By supplying the second driving signal to the piezoelectric elements 15b and 15d of the actuator unit 15, the emission end of the illumination fiber 12 is swung in a spiral shape. Are scanned by a spiral scanning path as shown in FIGS.

  Specifically, at time T1, illumination light is irradiated to a position corresponding to the center point A of the irradiation position of the illumination light on the surface of the subject. Thereafter, as the amplitudes of the first and second drive signals increase from time T1 to time T2, the irradiation position of the illumination light on the surface of the subject starts from the center point A and starts to the first spiral scanning path. Further, when the time T2 is reached, the illumination light is irradiated to the outermost point B of the illumination light irradiation position on the surface of the subject (see FIG. 4). Then, as the amplitudes of the first and second drive signals decrease from time T2 to time T3, the irradiation position of the illumination light on the surface of the subject is scanned in the second spiral shape from the outermost point B to the inside. When it is displaced so as to draw a path and further reaches time T3, illumination light is irradiated to the center point A on the surface of the subject (see FIG. 5).

  That is, the actuator unit 15 is emitted to the subject through the emission end by swinging the emission end of the illumination fiber 12 based on the first and second drive signals supplied from the driver unit 22. The illumination light irradiation position can be displaced along the spiral scanning path shown in FIGS.

The detection unit 23 includes a duplexer 36, detectors 37a, 37b, and 37c, and A / D converters 38a, 38b, and 38c.
The demultiplexer 36 includes a dichroic mirror and the like, and separates the return light emitted from the light emitting surface of the light receiving fiber 13 into light of R (red), G (green), and B (blue) color components. Then, the light is emitted to the detectors 37a, 37b, and 37c.

  The detector 37a includes, for example, an avalanche photodiode, and sequentially detects the intensity of the R light output from the branching filter 36 at every predetermined detection timing, and an analog signal corresponding to the detected intensity of the R light. An R signal is generated and output to the A / D converter 38a. The detector 37b has, for example, an avalanche photodiode or the like, sequentially detects the intensity of the G light output from the demultiplexer 36 at every predetermined detection timing, and outputs an analog signal corresponding to the detected intensity of the G light. A G signal is generated and output to the A / D converter 38b. The detector 37c has, for example, an avalanche photodiode or the like, sequentially detects the intensity of B light output from the demultiplexer 36 at every predetermined detection timing, and outputs an analog signal corresponding to the detected intensity of B light. A B signal is generated and output to the A / D converter 38c. In the present embodiment, the predetermined detection timing in the detectors 37a, 37b, and 37c relates to the sampling period and the number of samplings per period included in the endoscope drive information read from the memory 16 of the endoscope 2. Determined based on information. For example, when the sampling cycle is Ps and the number of samplings per cycle is Ns, the detection timing is the timing for each Ps / Ns. This Ps / Ns is also a sampling time described later.

  The A / D converter 38a converts the analog R signal output from the detector 37a into a digital R signal, and converts the converted R signal into return light (return light in the red wavelength band) from the subject. It outputs to the controller 25 as light intensity information. The A / D converter 38b converts the analog G signal output from the detector 37b into a digital G signal, and converts the converted G signal into return light (return light in the green wavelength band) from the subject. It outputs to the controller 25 as light intensity information. The A / D converter 38c converts the analog B signal output from the detector 37c into a digital B signal, and converts the converted B signal into return light (return light in the blue wavelength band) from the subject. It outputs to the controller 25 as light intensity information.

As described above, in the present embodiment, the detection unit 23 realizes a function as a detection unit for sequentially detecting the light intensity information of the return light from the subject at each irradiation position.
The memory 24 stores various control information used when the main device 3 is controlled. Further, the memory 24 stores the same-size interpolation parameter and the enlargement interpolation parameter generated by an interpolation parameter generation unit 25d described later of the controller 25.

  The controller 25 is configured by an integrated circuit such as an FPGA (Field Programmable Gate Array), for example, and includes a light source control unit 25a, a scan control unit 25b, an image generation unit 25c, and an interpolation parameter generation unit 25d.

  Based on the control information read from the memory 24, the light source control unit 25a performs control for causing the light sources 31a, 31b, and 31c to emit light at the same time, for example.

  The scanning control unit 25b has, for example, a signal waveform as shown in FIG. 3 based on information related to the driving frequency, the amplitude coefficient, and the like included in the endoscope driving information read from the memory 16 of the endoscope 2. The driver unit 22 is controlled to generate a drive signal.

  The image generation unit 25c generates a 1 × magnification observation image for one frame using the digital signal (light intensity information) output from the detection unit 23 and the 1 × interpolation parameter read from the memory 24. The generated single-magnification observation image for one frame is sequentially output to the display device 4. In the present embodiment, the image generation unit 25c performs, for example, equal magnification observation based on the light intensity information sequentially detected along the spiral irradiation locus (spiral scanning locus) illustrated in FIG. 4 and the equal magnification interpolation parameter. An image can be generated.

  The image generation unit 25c generates an enlarged observation image for one frame using the digital signal (light intensity information) output from the detection unit 23 and the interpolation parameter for enlargement read from the memory 24, and The generated enlarged observation image for one frame is sequentially output to the display device 4. In the present embodiment, for example, the image generation unit 25c generates an enlarged observation image based on the light intensity information sequentially detected along the spiral irradiation locus (spiral scanning locus) shown in FIG. 4 and the interpolation parameter for enlargement. It is possible to generate.

The details of the procedure for generating the same-size observation image and the procedure for generating the enlarged observation image in the image generation unit 25c will be described later with reference to FIGS.
The interpolation parameter generation unit 25d is based on information related to the driving frequency, amplitude coefficient, sampling period, and number of samples per period included in the endoscope driving information read from the memory 16 of the endoscope 2. An equal magnification interpolation parameter and an enlargement interpolation parameter are generated, and the generated equal magnification interpolation parameter and enlargement interpolation parameter are stored in the memory 24.

The details of the procedure for generating the equal-magnification interpolation parameter and the enlargement interpolation parameter in the interpolation parameter generation unit 25d will be described later with reference to FIGS.
The display device 4 includes, for example, a monitor and displays an observation image output from the main body device 3.

  The input device 5 includes, for example, a keyboard or a touch panel, and can give instructions for setting the magnification of the observation image displayed on the display device 4 to the same magnification or enlargement. Note that the input device 5 is not limited to being configured as a separate device from the main body device 3 as shown in FIG. 1. For example, the input device 5 may be configured as an interface integrated with the main body device 3. .

  In the scanning endoscope apparatus 1 configured as described above, the illumination fiber 12 is an example of a light guide unit that guides illumination light for illuminating a subject and emits the light from the exit end. . The actuator unit 15 is an example of a scanning unit that displaces the irradiation position of the illumination light emitted to the subject by swinging the emission end at a predetermined rate of change of oscillation. The detection unit 23 is an example of a light detection unit that detects return light of illumination light emitted to a subject and generates a signal corresponding to the return light. The memory 24 stores an enlargement interpolation parameter determined based on the irradiation position of the illumination light when the scanning unit swings the emission end at a swing change rate larger than a predetermined swing change rate. It is an example of a part. The image generation unit 25c is an example of an image generation unit that generates an enlarged observation image based on the signal generated by the light detection unit and the enlargement interpolation parameter stored in the storage unit. The interpolation parameter generation unit 25d calculates the irradiation position of the illumination light when the scanning unit swings the emission end at a swing change rate larger than a predetermined swing change rate, and based on the calculation result, enlargement is performed. It is an example of the interpolation parameter production | generation part which produces | generates an interpolation parameter.

  Next, as an example of processing performed in the scanning endoscope apparatus 1, an interpolation parameter generation processing performed in the interpolation parameter generation unit 25d and an observation image generation processing performed in the image generation unit 25c will be described.

In the description of these processes, the description is given on the assumption that the image generation unit 25c generates an observation image using an 8-point interpolation method as an example of an interpolation method.
First, interpolation parameter generation processing will be described with reference to FIGS.

  FIG. 6 is a flowchart showing the flow of the interpolation parameter generation process. FIG. 7 is a diagram schematically illustrating a process of calculating the irradiation position of the illumination light for each sampling time. FIG. 8 is a diagram schematically showing a process of associating eight irradiation positions for interpolation with each pixel area on the image area (image drawing area). FIG. 9 is a diagram schematically showing a process of associating sampling times and weighting coefficients of eight irradiation positions for interpolation with each pixel area on the image area (image drawing area). FIG. 10 is a diagram illustrating an example of the signal waveform of the drive signal when the amplitude change rate of the drive signal of the signal waveform illustrated in FIG. 3 is enlarged.

The interpolation parameter generation processing starts when the endoscope 2 is connected to the main body device 3 and the controller 25 reads the endoscope information from the memory 16 of the endoscope 2.
As illustrated in FIG. 6, the interpolation parameter generation unit 25d first generates an equal magnification interpolation parameter (step S601). The generation of the equal magnification interpolation parameter is performed based on endoscope driving information included in the endoscope information.

  More specifically, first, the interpolation parameter generation unit 25d is determined based on the information on the driving frequency and the amplitude coefficient included in the endoscope driving information as schematically shown in FIG. When a driving signal having a signal waveform (for example, a driving signal as shown in FIG. 3) is supplied to the actuator unit 15, the locus of the irradiation position of the illumination light is calculated, and the irradiation position of the illumination light for each sampling time is calculated. . That is, the table A indicating the irradiation position of the illumination light for each sampling time in such a case is generated. Here, the sampling time is determined based on information related to the sampling period and the number of samplings per period included in the endoscope driving information. In FIG. 7, t1, t2, t3,..., Tn indicate times for each sampling time (that is, sampling times). x1, x2, x3,..., xn represent X coordinates of irradiation positions for each sampling time. y1, y2, y3,... yn indicate Y coordinates of the irradiation position for each sampling time.

  Next, as schematically shown in FIG. 8, the interpolation parameter generation unit 25d, based on the calculated irradiation position (table A) for each sampling time, all pixel regions on the image region (image drawing region). Are associated with eight irradiation positions for interpolation. In other words, a table B indicating the correspondence between the eight irradiation positions (points) for interpolation with respect to each pixel region is generated. In this association, each pixel region is a processing target, and for each pixel region to be processed, there are four image regions (first quadrant, second quadrant, third quadrant, fourth quadrant). In each quadrant, two pixel areas on the image area that are close to the pixel area to be processed and that correspond to the irradiation position are selected from each divided image area. Then, eight irradiation positions corresponding to a total of eight pixel areas selected two from each divided image area are associated with the pixel area to be processed as eight irradiation positions for interpolation. Each pixel area is specified by pixel area coordinates on the image area. By such association, for example, in FIG. 8, the pixel region (0, 0) has eight irradiation positions (x10, y10), (x82, y82), ..., (x39, y39) for interpolation. Is associated. Note that the table B shown in FIG. 8 shows an example in which an observation image of 100 × 100 pixels is generated (table B and table C shown in FIG. 9 and equal-magnification interpolation parameters shown in FIG. 12 described later). The same).

  Next, as schematically shown in FIG. 9, the interpolation parameter generation unit 25d includes the calculated irradiation position (table A) for each sampling time and eight interpolations associated with each pixel region. Based on the irradiation position (table B), sampling times and weighting factors of eight irradiation positions for interpolation are associated with each pixel region. That is, a table C indicating the correspondence between the sampling times (Time) and weighting factors (Weight) of the eight irradiation positions for interpolation for each pixel region is generated. The table C generated at this time is an equal magnification interpolation parameter.

  Here, the sampling time of the irradiation position for interpolation is determined based on the irradiation position (table A) for each sampling time. For example, in FIG. 9, the sampling time of the irradiation position (x10, y10) for interpolation associated with the pixel area (0, 0) in the table B is the sampling time of the irradiation position (x10, y10) in the table A. Since it is t10, it is determined as t10 (see Table C).

Further, the weighting coefficient of the irradiation position for interpolation is calculated by the following equation (1).
Weight coefficient = weight value / weight value total value Formula (1)
Here, the weight value is calculated by the following equation (2).

Weight value = 1− (Distance with associated pixel area / Distance total value) Expression (2)
For example, in FIG. 9, the weighting coefficient of the irradiation position (x10, y10) for interpolation associated with the pixel area (0, 0) in the table B is obtained as follows. First, as the “distance to the associated pixel area” in Equation (2), the pixel area (0, 0) and the pixel area on the image area corresponding to the irradiation position for interpolation (x10, y10) The distance between them (denoted as d) is obtained. Further, as the “distance total value” in the expression (2), the pixel area (0, 0) and the eight irradiation positions (x10, y10), (x82, y82),..., (X39, y39) for interpolation. ) Is obtained as a total value (referred to as Sd) of distances between each of the eight pixel areas on the image area. Then, a weight value (w) is obtained for the irradiation position (x10, y10) for interpolation by using equation (2) using d and Sd. Further, as the “weight value total value” in the expression (1), w and the other seven irradiation positions (x82, y82) for interpolation obtained in the same manner as this w, (x39, y39) ) Together with the weight value for each of them (Sw). Then, the weighting factor k1-1 of the irradiation position (x10, y10) for interpolation associated with the pixel region (0, 0) is obtained by Equation (1) using w and Sw (see Table C). .

  When the same-size interpolation parameter is generated in this way, as shown in FIG. 6, the interpolation parameter generation unit 25d next generates an enlargement interpolation parameter (step S602). The enlargement interpolation parameter is generated in the same manner as the generation of the equal magnification interpolation parameter except for a part.

  More specifically, first, the interpolation parameter generation unit 25d is based on information related to the drive frequency and amplitude coefficient included in the endoscope drive information, and a drive signal (for example, FIG. 3) determined based on the information. The drive position of the illumination light is calculated when the drive signal (for example, the drive signal shown in FIG. 10) when the amplitude change rate of the drive signal is increased is supplied to the actuator unit 15. The irradiation position of the illumination light for each sampling time is calculated. That is, the table A indicating the irradiation position of the illumination light for each sampling time in such a case is generated.

  Thereafter, in the same manner as the generation of the equal-magnification interpolation parameter, a table B indicating the correspondence between the eight irradiation positions for interpolation with respect to each pixel region is generated based on the table A. Subsequently, the table A and Based on the table B, a table C is generated that indicates the correspondence between the sampling times and weighting factors of the eight irradiation positions for interpolation for each pixel region. The table C generated at this time becomes an enlargement interpolation parameter.

  When the enlargement interpolation parameter is generated in this way, the interpolation parameter generation unit 25d then saves in the memory 24 the same-size interpolation parameter generated in step S601 and the enlargement interpolation parameter generated in step S602. (Store) (step S603), and the interpolation parameter generation process ends.

  When a drive signal (for example, a drive waveform as shown in FIG. 3) having a signal waveform determined based on information related to the drive frequency and amplitude coefficient included in the endoscope drive information is supplied to the actuator unit 15. When the exit end of the illumination fiber 12 swings at a predetermined swing change rate, the drive signal (for example, the drive signal shown in FIG. 10) when the amplitude change rate of the drive signal is expanded is an actuator. When supplied to the section 15, the exit end of the illumination fiber 12 swings at a swing change rate larger than a predetermined swing change rate.

Next, the observation image generation process will be described with reference to FIGS.
Note that the image generation unit 25c that performs the observation image generation processing actually performs image processing based on the light intensity information of the R light, the G light, and the B light that are detected by demultiplexing in the detection unit 23. The processing for setting the luminance information of each color of R, G, and B in each pixel area on the area is performed in parallel or sequentially. The description will be made with one process without distinction.

  FIG. 11 is a flowchart showing a flow of observation image generation processing for one frame. FIG. 12 is a diagram schematically illustrating a processing process for generating a 1 × -magnification observation image. FIG. 13 is a diagram schematically illustrating a conventional enlarged observation image generation process and an enlarged observation generation process according to the present embodiment. FIG. 14 is a diagram illustrating an example of a temporal change in the swing width when the swing of the emission end of the illumination fiber 12 is controlled by a drive signal based on a sine wave. FIG. 15 is a diagram illustrating an example of the trajectory of the scanning line (the trajectory of the illumination light irradiation position) when the oscillation of the emission end of the illumination fiber 12 is controlled by the drive signal based on the sine wave.

  As shown in FIG. 11, when the observation image generation process for one frame is started, the image generation unit 25c first performs a light reception process (step S1101). In this light reception processing, scanning necessary for generating an observation image for one frame (for example, scanning of the scanning path shown in FIG. 4) is performed, and at this time, a digital signal output from the detection unit 23 at every sampling time. (Light intensity information) is acquired by the image generation unit 25c. In the scanning at this time, a drive signal (for example, a drive waveform as shown in FIG. 3) having a signal waveform determined based on information related to the drive frequency and the amplitude coefficient included in the endoscope drive information is the actuator unit 15. To be supplied.

Next, the image generation unit 25c determines whether equal magnification or enlargement is set as the magnification of the observation image to be generated (displayed) (step S1102).
When the same magnification is set as the magnification of the observation image, the image generation unit 25c stores the light intensity information for each sampling time (light intensity information at each sampling time) acquired in step S1101 and the memory 24. Based on the same-magnification interpolation parameter, an observation image (that is, an observation image with the same magnification) for one frame is generated (step S1103).

  In the generation of the one-magnification observation image for one frame, as schematically shown in FIG. 12, the pixel value (for example, luminance information) of each pixel of the equal-magnification observation image corresponds to the corresponding pixel in the equal-magnification interpolation parameter. It is determined based on the sampling times and weighting factors of the eight irradiation positions for interpolation associated with the region, and the light intensity information (light reception data) at the sampling times of the eight irradiation positions for interpolation. .

  For example, in FIG. 12, the pixel value of the pixel (0, 0) of the normal magnification observation image is the eight irradiations for interpolation associated with the corresponding pixel region (0, 0) in the normal magnification interpolation parameter. Position sampling times (t10, t82,..., T39) and weighting factors (k1-1, k1-2,..., K1-8) and their eight sampling times (t10, t82,... , T39) based on the light intensity information. In this case, using light intensity information and eight weighting factors (k1-1, k1-2,..., K1-8) at eight sampling times (t10, t82,..., T39), For example, a weighted average value of the light intensity information is obtained, and the weighted average value at this time is determined as the pixel value of the pixel (0, 0).

  On the other hand, as shown in FIG. 11, when enlargement is set as the magnification of the observation image, the image generation unit 25 c stores the light intensity information for each sampling time acquired in step S <b> 1101 and the memory 24. Based on the interpolation parameter for enlargement, an observation image (that is, an enlarged observation image) with an enlargement magnification of one frame is generated (step S1104). The generation of the enlarged observation image for one frame is performed in the same manner as the generation of the normal observation image for one frame except that the enlargement interpolation parameter is used instead of the normal magnification interpolation parameter.

  When the same-size observation image or enlarged observation image for one frame is generated in this way, the observation image generation processing for one frame is completed. Actually, such an observation image generation process for one frame is repeatedly performed. Then, the generated one-magnification observation image or enlarged observation image for one frame is sequentially output to the display device 4 and is sequentially displayed by the display device 4, for example.

  According to such an observation image generation process, when an enlarged observation image is generated, conventionally, as schematically shown in FIG. 13, an observation image (in the present embodiment) is conventionally based on the light intensity information at each irradiation position. In contrast to the generation of the enlarged observation image by performing the enlarged image processing on a part of the observation image after the generation of the same magnification observation image) Since an observation image as a magnified observation image is directly generated based on the light intensity information, it is possible to generate a magnified observation image in which image quality deterioration is suppressed as compared with the conventional case.

  Further, when the oscillation of the emission end of the illumination fiber 12 is controlled by a drive signal based on a sine wave as in the present embodiment, for example, the illumination change with time change as shown in FIG. The oscillation width of the exit end of the fiber 12 changes. Further, in this case, for example, as shown in FIG. 15, the irradiation position for each sampling time in the portion near the center and the portion near the outer periphery in the locus of the spiral scanning line (the locus of the irradiation position of the illumination light) A large number of light intensity information can be obtained. Therefore, for example, an enlarged observation image of a portion close to the center (for example, a portion of the square frame 72 in FIG. 15) can obtain an image quality equivalent to a normal magnification observation image. Note that the trajectory of the scanning line in the portion of the square frame 72 shown in FIG. 15 corresponds to the temporal change of the swinging width in the portion of the square frame 71 shown in FIG.

As described above, according to the scanning endoscope apparatus 1 according to the present embodiment, it is possible to generate a magnified observation image in which image quality deterioration is suppressed.
The scanning endoscope apparatus 1 according to the present embodiment may be modified as follows.

  For example, the image generation unit 25c generates an observation image using an interpolation method other than the 8-point interpolation method, and the interpolation parameter generation unit 25d sets the same-size interpolation parameter and the enlargement interpolation parameter corresponding to the interpolation method. You may comprise so that it may produce | generate.

  Further, for example, the interpolation parameter generation unit 25d may be configured to generate a plurality of enlargement interpolation parameters corresponding to a plurality of different enlargement magnifications as the enlargement interpolation parameter. In this case, an instruction for setting the magnification of the observation image displayed on the display device 4 to the same magnification or any of a plurality of different magnifications via the input device 5 is possible, and the image The generation unit 25c may be configured to generate an observation image using an interpolation parameter corresponding to the set magnification.

  For example, the scanning endoscope apparatus 1 may be configured not to include the interpolation parameter generation unit 25d. In this case, the same-size interpolation parameter and the enlargement interpolation parameter may be stored in the memory 24 in advance, or the same-size interpolation parameter and the enlargement interpolation parameter are input from the outside and stored in the memory 24. It is good also as a structure to be.

  As described above, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, you may delete some components of all the components shown by embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Scanning endoscope apparatus 2 Endoscope 3 Main body apparatus 4 Display apparatus 5 Input apparatus 11 Insertion part 12 Illumination fiber 13 Light reception fiber 14 Illumination optical system 14a, 14b Lens 15 Actuator part 15a, 15b, 15c, 15d Piezoelectric Element 16 Memory 21 Light source unit 22 Driver unit 23 Detection unit 24 Memory 25 Controller 25a Light source control unit 25b Scan control unit 25c Image generation unit 25d Interpolation parameter generation units 31a, 31b, 31c Light source 32 Mux 33 Signal generators 34a, 34b D / A converter 35 Amplifier 36 Dividers 37a, 37b, 37c Detectors 38a, 38b, 38c A / D converter 41 Ferrules 42a, 42b, 42c, 42d Side face 61 Connector part 62 Connector receiving part 71, 72 Square frame

Claims (5)

A light guide that guides the illumination light for illuminating the subject and emits it from the exit end; and
A scanning unit for displacing the irradiation position of the illumination light emitted to the subject by oscillating the emission end at a predetermined oscillation change rate;
A light detection unit that detects return light of the illumination light emitted to the subject and generates a signal corresponding to the return light;
A storage for storing an interpolation parameter for enlargement determined based on the irradiation position of the illumination light when the scanning unit swings the emission end at a swing change rate larger than the predetermined swing change rate. And
An image generation unit that generates an enlarged observation image based on the signal generated by the light detection unit and the interpolation parameter for enlargement stored in the storage unit;
A scanning endoscope apparatus comprising: An irradiation position of the illumination light when the scanning unit swings the emission end at a swing change rate larger than the predetermined swing change rate, and the enlargement interpolation parameter is calculated based on the calculation result An interpolation parameter generation unit for generating
The scanning endoscope apparatus according to claim 1. The storage unit further stores equal-magnification interpolation parameters determined based on the irradiation position of the illumination light when the scanning unit swings the emission end at the predetermined swing change rate. ,
The image generation unit further generates a 1 × magnification observation image based on the signal generated by the light detection unit and the 1 × magnification interpolation parameter stored in the storage unit,
The scanning endoscope apparatus according to claim 1. The scanning unit calculates the irradiation position of the illumination light when the emission end is swung at the predetermined swing change rate, and generates the equalization interpolation parameter based on the calculation result, The scanning unit calculates the irradiation position of the illumination light when the emitting end is swung at a swing change rate larger than the predetermined swing change rate, and based on the calculation result, the enlargement interpolation parameter An interpolation parameter generation unit that performs generation;
The scanning endoscope apparatus according to claim 3. An image generation method executed in a scanning endoscope apparatus,
The illumination light is emitted from an emission end of a light guide that guides illumination light for illuminating a subject,
Displace the irradiation position of the illumination light emitted to the subject by oscillating the emission end at a predetermined oscillation change rate,
Detecting return light of the illumination light emitted to the subject, generating a signal according to the return light,
Based on the generated signal and an enlargement interpolation parameter determined based on the irradiation position of the illumination light when the emission end is swung at a swing change rate larger than the predetermined swing change rate. To generate a magnified observation image,
An image generation method characterized by the above.