Abstract:
A scanning endoscope system has a light guide portion that guides an illuminating light, a drive portion capable of causing the light guide portion to swing so that an irradiation position of the illuminating light draws a locus corresponding to a predetermined scanning pattern, a light detecting portion that receives a return light of the illuminating light and outputs a signal, a control portion that drives the drive portion to perform scan so that the irradiation position of the illuminating light becomes a locus in a spiral shape, and an image generating portion that generates an image of an object based on a signal outputted from the light detecting portion in a predetermined timing, wherein the control portion further performs control for driving the drive portion so that the irradiation position of the illuminating light circles on a same circumference in the predetermined timing.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation application of PCT/JP2013/063023 filed on May 9, 2013 and claims benefit of Japanese Application No. 2012-206102 filed in Japan on Sep. 19, 2012, the entire contents of which are incorporated herein by this reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a scanning endoscope system, and particularly relates to a scanning endoscope system that scans an object and acquires an image. 
         [0004]    2. Description of the Related Art 
         [0005]    In endoscopes in a medical field, in order to reduce the burdens on subjects, various techniques are proposed, which are for reducing the diameters of the insertion portions that are inserted into the body cavities of the subjects. As one example of the techniques as above, a scanning endoscope that does not have a solid image pickup device in the portion corresponding to the aforementioned insertion portion, and a system that is configured by including the scanning endoscope are known. 
         [0006]    More specifically, the system including the aforementioned scanning endoscope is configured to scan an object in a scanning pattern that is set in advance by swinging the distal end portion of an illuminating fiber that guides an illuminating light that is emitted from the light source portion, receive the return light from the object with light receiving fibers disposed around the illuminating fiber, and generate an image of the object by using the signals obtained by separating the return light that is received by the light receiving fibers into respective color components. 
         [0007]    As the system including the configuration as described above, the endoscope apparatus as disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2010-131112 has been conventionally known. 
       SUMMARY OF THE INVENTION 
       [0008]    A scanning endoscope system of one aspect of the present invention has a light guide portion that guides an illuminating light emitted from a light source, a drive portion capable of causing the light guide portion to swing in such a manner that an irradiation position of the illuminating light that is irradiated to an object via the light guide portion draws a locus corresponding to a predetermined scanning pattern, a light detecting portion that is configured to receive a return light of the illuminating light that is irradiated to the object, generate a signal corresponding to intensity of the return light, and output the signal, a control portion that performs control for driving the drive portion to perform scanning so that the irradiation position of the illuminating light becomes a locus in a spiral shape, and an image generating portion that generates an image of the object based on a signal that is outputted from the light detecting portion in a predetermined timing of timings at which the drive portion is controlled, wherein the control portion further performs control for driving the drive portion so that the irradiation position of the illuminating light circles on a same circumference in the predetermined timing at which the image generating portion generates the image of the object. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a diagram showing a configuration of an essential part of a scanning endoscope system according to an embodiment; 
           [0010]      FIG. 2  is a diagram for explaining one example of a virtual XY plane that is set on a surface of an object; 
           [0011]      FIG. 3  is a diagram for explaining one example of a signal waveform of a drive signal that is supplied to an actuator provided in the scanning endoscope; 
           [0012]      FIG. 4  is a diagram for explaining a locus in a first spiral shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned; 
           [0013]      FIG. 5  is a diagram for explaining a locus in a second spiral shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned; 
           [0014]      FIG. 6  is a diagram for explaining one example of a locus in a circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned; 
           [0015]      FIG. 7  is a diagram for explaining a first modification of a signal waveform of a drive signal that is supplied to the actuator provided in the scanning endoscope; 
           [0016]      FIG. 8  is a diagram for explaining an example, which differs from  FIG. 6 , of the locus in the circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned; 
           [0017]      FIG. 9  is a diagram for explaining a second modification of the signal waveform of the drive signal that is supplied to the actuator provided in the scanning endoscope; 
           [0018]      FIG. 10  is a diagram for explaining an example, which differs from  FIG. 6  and  FIG. 8 , of the locus in the circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned; 
           [0019]      FIG. 11  is a diagram for explaining an example, which differs from  FIG. 6 ,  FIG. 8  and  FIG. 10 , of the locus in the circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned; 
           [0020]      FIG. 12  is a diagram for explaining a third modification of the signal waveform of the drive signal that is supplied to the actuator that is provided in the scanning endoscope; and 
           [0021]      FIG. 13  is a diagram for explaining a fourth modification of the signal waveform of the drive signal that is supplied to the actuator that is provided in the scanning endoscope. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 
         [0023]      FIG. 1  to  FIG. 13  relate to the embodiment of the present invention.  FIG. 1  is a diagram showing an essential part of a scanning endoscope system according to the embodiment. 
         [0024]    As shown in  FIG. 1 , for example, a scanning endoscope system  1  is configured by having a scanning endoscope  2  that is inserted into a body cavity of a subject, a main body apparatus  3  that is connected to the scanning endoscope  2 , and a monitor  4  that is connected to the main body apparatus  3 . 
         [0025]    The scanning endoscope  2  is configured by having an insertion portion  11  that is formed by including an elongated shape and flexibility capable of being inserted into a body cavity of a subject. Note that at a proximal end portion of the insertion portion  11 , a connector or the like not illustrated for detachably connecting the scanning endoscope  2  to the main body apparatus  3  is provided. 
         [0026]    An illuminating fiber  12  including a function as a light guide portion that guides an illuminating light supplied from a light source unit  21  of the main body apparatus  3  to an objective optical system  14 , and light receiving fibers  13  that receive a return light from an object and guide the return light to a detection unit  23  of the main body apparatus  3  are respectively inserted through a portion from the proximal end portion to a distal end portion inside the insertion portion  11 . 
         [0027]    An end portion including a light incident face of the illuminating fiber  12  is disposed in a multiplexer  32  provided inside the main body apparatus  3 . Further, an end portion including a light exit face of the illuminating fiber  12  is disposed in a state in which the end portion is not fixed by a fixing member or the like, in a vicinity of a light incident face of a lens  14   a  provided at the distal end portion of the insertion portion  11 . 
         [0028]    An end portion including a light incident face of the light receiving fiber  13  is fixedly disposed in a surrounding of a light exit face of a lens  14   b,  in a distal end face of the distal end portion of the insertion portion  11 . Further, an end portion including a light exit face of the light receiving fiber  13  is disposed in a demultiplexer  36  provided inside the main body apparatus  3 . 
         [0029]    The objective optical system  14  is configured by having the lens  14   a  on which the illuminating light from the illuminating fiber  12  is incident, and the lens  14   b  that emits the illuminating light passing through the lens  14   a  to an object. 
         [0030]    An actuator  15  that drives based on a drive signal that is outputted from a driver unit  22  of the main body apparatus  3  is attached to an intermediate portion of the illuminating fiber  12  in a distal end portion side of the insertion portion  11 . 
         [0031]    Here, explanation will be made hereinafter with a case in which an XY plane as shown in  FIG. 2  is set on a surface of an object as a virtual plane that is perpendicular to an insertion axis (or an optical axis of the objective optical system  14 ) that corresponds to an axis in a longitudinal direction of the insertion portion  11  being cited as an example.  FIG. 2  is a diagram for explaining one example of the virtual XY plane that is set on the surface of an object. 
         [0032]    More specifically a point SA on the XY plane of  FIG. 2  shows an intersection point of the insertion axis and a paper surface in a case in which the insertion axis of the insertion portion  11  is assumed to be present in a direction corresponding to a direction from a front side of the paper surface to a back side and is virtually set. Further, an X axis direction in the XY plane of  FIG. 2  is set as a direction toward a right side from a left side of the paper surface. Further, a Y axis direction in the XY plane of  FIG. 2  is set as a direction toward an upper side from a lower side of the paper surface. Further, the X axis and the Y axis that configure the XY plane of  FIG. 2  intersect each other in the point SA. 
         [0033]    The actuator  15  is configured by having an X axis actuator (not illustrated) that acts so as to swing the end portion including the light exit face of the illuminating fiber  12  in the X axis direction based on a first drive signal that is outputted from the driver unit  22  of the main body apparatus  3 , and a Y axis actuator (not illustrated) that acts to swing the end portion including the light exit face of the illuminating fiber  12  in the Y axis direction based on a second drive signal that is outputted from the driver unit  22  of the main body apparatus  3 . The actuator  15  can cause the end portion including the light exit face of the illuminating fiber  12  to swing so that an irradiation position of the illuminating light with which the object is irradiated draws a locus corresponding to a predetermined scanning pattern by actions of the X axis actuator and the Y axis actuator as described above. 
         [0034]    Inside the insertion portion  11 , a memory  16  is provided, in which endoscope information including various kinds of information such as individual identification information of the scanning endoscope  2  is stored in advance. The endoscope information that is stored in the memory  16  is read by a controller  25  of the main body apparatus  3  when the scanning endoscope  2  and the main body apparatus  3  are connected. 
         [0035]    The main body apparatus  3  is configured by having the light source unit  21 , the driver unit  22 , the detection unit  23 , a memory  24  and the controller  25 . 
         [0036]    The light source unit  21  is configured by having a light source  31   a,  a light source  31   b,  a light source  31   c  and the multiplexer  32 . 
         [0037]    The light source  31   a  includes, for example, a laser light source, and is configured to emit a light of a wavelength band of a red color (hereinafter, also called an R light) to the multiplexer  32  when the light source  31   a  is turned on by control of the controller  25 . 
         [0038]    The light source  31   b  includes, for example, a laser light source, and is configured to emit a light of a wavelength band of a green color (hereinafter, also called a G light) to the multiplexer  32  when the light source  31   b  is turned on by control of the controller  25 . 
         [0039]    The light source  31   c  includes, for example, a laser light source, and is configured to emit a light of a wavelength band of a blue color (hereinafter, also called a B light) when the light source  31   c  is turned on by control of the controller  25 . 
         [0040]    The multiplexer  32  is configured to multiplex the R light emitted from the light source  31   a,  the G light emitted from the light source  31   b,  and the B light emitted from the light source  31   c  to be able to supply the multiplexed lights to the light incident face of the illuminating fiber  12 . 
         [0041]    The driver unit  22  is configured by having a signal generator  33 , digital-analogue (hereinafter, called D/A) converters  34   a  and  34   b,  and an amplifier  35 . 
         [0042]    The signal generator  33  is configured to generate a signal of a predetermined waveform as shown in  FIG. 3 , for example, to output the signal to the D/A converter  34   a,  as the first drive signal that swings the end portion including the light exit face of the illuminating fiber  12  in the X axis direction based on control of the controller  25 .  FIG. 3  is a diagram for explaining one example of the signal waveform of the drive signal that is supplied to the actuator provided in the scanning endoscope. 
         [0043]    Further, the signal generator  33  is configured to generate a signal of a waveform obtained by a phase of the aforementioned first drive signal being shifted by 90° to output the signal to the D/A converter  34   b,  as the second drive signal that swings the end portion including the light exit face of the illuminating fiber  12  in the Y axis direction based on control of the controller  25 . 
         [0044]    The D/A converter  34   a  is configured to convert the digital first drive signal outputted from the signal generator  33  into an analogue first drive signal to output the analogue first drive signal to the amplifier  35 . 
         [0045]    The D/A converter  34   b  is configured to convert the digital second drive signal outputted from the signal generator  33  into an analogue second drive signal to output the analogue second drive signal to the amplifier  35 . 
         [0046]    The amplifier  35  is configured to amplify the first and the second drive signals that are outputted from the D/A converters  34   a  and  34   b  to output the first and the second drive signals to the actuator  15 . 
         [0047]    Here, an amplitude value (a signal level) of the waveform of the drive signal illustrated in  FIG. 3  gradually decreases with a time point T 1  at which the amplitude value becomes a maximum value as a starting point, and gradually increases immediately after the amplitude value becomes zero at a time point T 2  to be the maximum value at a time point T 3 . The amplitude value gradually decreases immediately after the amplitude value keeps the maximum value in a time period from the time point T 3  to a time point T 4 , and becomes zero at a time point T 5 . 
         [0048]    The first drive signal including the waveform as shown in  FIG. 3  is supplied to the X axis actuator of the actuator  15 , and the second drive signal obtained by the phase of the first drive signal being shifted by 90° is supplied to the Y axis actuator of the actuator  15 . Thereby the end portion including the light exit face of the illuminating fiber  12  is caused to swing with the point SA as a center. Further, in response to the swing of the illuminating fiber  12  as above, the locus of the illuminating light with which the surface of the object is irradiated changes in a sequence of  FIG. 4  to  FIG. 5  to  FIG. 6  to  FIG. 4  . . . .  FIG. 4  is a diagram for explaining a locus in a first spiral shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned.  FIG. 5  is a diagram for explaining a locus in a second spiral shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned.  FIG. 6  is a diagram for explaining a locus in a circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned. 
         [0049]    More specifically, in the time point T 1  corresponding to a scan start timing for an object, a point YMAX that is an outermost point of irradiation coordinates of the illuminating light in the surface of the object is irradiated with the illuminating light. Subsequently, as the amplitude values of the first and the second drive signals decrease from the time point T 1  to the time point T 2 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point YMAX as the starting point, and further, when the time point T 2  arrives, a position corresponding to a point SA in the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0050]    Further, as the amplitude values of the first and the second drive signals increase from the time point T 2  to the time point T 3 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the second spiral shape outward with the point SA as the starting point. Further, when the time point T 3  arrives, the point YMAX that is the outermost point of the irradiation coordinates of the illuminating light in the surface of the object is irradiated with the illuminating light (see  FIG. 5 ). 
         [0051]    Thereafter, in a time period from the time point T 3  until the time point T 4 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to circle a predetermined times along a locus in a circular shape with a radius RMAX that corresponds to a distance between the point SA and the point YMAX (see  FIG. 6 ). 
         [0052]    Subsequently, as the amplitude values of the first and the second drive signals decrease from the time point T 4  to the time point T 5 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point YMAX as the starting point. Further, when the time point T 5  arrives, the point SA in the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0053]    The detection unit  23  is configured by having the demultiplexer  36 , detectors  37   a,    37   b  and  37   c,  and analogue-digital (hereinafter, called A/D) converters  38   a,    38   b  and  38   c.    
         [0054]    The demultiplexer  36  includes a dichroic mirror or the like, and is configured to separate the return light emitted from the light exit face of the light receiving fiber  13  into lights of respective color components of R (red), G (green) and B (blue) to emit the lights to the detectors  37   a,    37   b  and  37   c.    
         [0055]    The detector  37   a  is configured to detect intensity of the R light that is outputted from the demultiplexer  36 , generate an analogue R signal corresponding to the detected intensity of the R light and output the analogue R signal to the A/D converter  38   a.    
         [0056]    The detector  37   b  is configured to detect intensity of the G light that is outputted from the demultiplexer  36 , generate an analogue G signal corresponding to the detected intensity of the G light and output the analogue G signal to the A/D converter  38   b.    
         [0057]    The detector  37   c  is configured to detect intensity of the B light that is outputted from the demultiplexer  36 , generate an analogue B signal corresponding to the detected intensity of the B light and output the analogue B signal to the A/D converter  38   c.    
         [0058]    The A/D converter  38   a  is configured to convert the analogue R signal that is outputted from the detector  37   a  into a digital R signal and output the digital R signal to the controller  25 . 
         [0059]    The A/D converter  38   b  is configured to convert the analogue G signal that is outputted from the detector  37   b  into a digital G signal and output the digital G signal to the controller  25 . 
         [0060]    The A/D converter  38   c  is configured to convert the analogue B signal that is outputted from the detector  37   c  into a digital B signal and output the digital B signal to the controller  25 . 
         [0061]    In the memory  24 , a control program for performing control of the main body apparatus  3  and the like are stored in advance. Further, in the memory  24 , the endoscope information that is read by the controller  25  of the main body apparatus  3  is stored. 
         [0062]    The controller  25  includes a CPU or the like, and is configured to read the control program stored in the memory  24 , and perform control of the light source unit  21  and the driver unit  22  based on the control program that is read. 
         [0063]    The controller  25  is configured to be able to generate an image based on the respective color signals that are outputted from the detection unit  23  and cause the monitor  4  to display the image, while the controller  25  keeps control for supplying the illuminating light to the illuminating fiber  12  from the light source unit  21 , and control for supplying the drive signal to the actuator  15  from the driver unit  22 , respectively. 
         [0064]    More specifically, the controller  25  generates an image corresponding to one frame based on the respective color signals outputted from the detection unit  23  in the time period corresponding to the time period from the time point T 1  to the time point T 2 , and an image corresponding to one frame based on the respective color signals outputted from the detection unit  23  in the time period corresponding to the time period from the time point T 2  to the time point T 3 , during the time period from the time point T 3  until the time point T 4  and causes the monitor  4  to display the images, while the controller  25  keeps control for supplying the illuminating light to the illuminating fiber  12  from the light source unit  21 , and control for supplying the drive signal to the actuator  15  from the driver unit  22  respectively. Namely, the respective color signals that are outputted from the detection unit  23  during the time period corresponding to the time period from the time point T 3  to the time point T 4  do not contribute to generation of the images. 
         [0065]    According to the embodiment described above, an action similar to the action in the time period from the time point T 3  to the time point T 4  described above is performed every fixed time period in which scanning for obtaining the image corresponding to two frames is completed. Therefore, according to the embodiment described above, a timing relating to irradiation of the illuminating light to the object, and a timing relating to generation of the image corresponding to the return light from the object can be favorably synchronized without control or the like that temporarily stops at least any one of swing of the illuminating fiber  12  and supply of the illuminating light to the illuminating fiber  12  being performed. As a result, according to the embodiment described above, stability of a frame rate at a time of observation using the scanning endoscope can be enhanced as compared with the conventional system. 
         [0066]    Note that according to the present embodiment, instead of the drive signal that includes the waveform illustrated in  FIG. 3 , a drive signal including a waveform as shown in  FIG. 7 , for example, may be supplied to the actuator  15 .  FIG. 7  is a diagram for explaining a first modification of the signal waveform of the drive signal that is supplied to the actuator provided in the scanning endoscope. 
         [0067]    Here, an amplitude value (a signal level) of the waveform of the drive signal illustrated in  FIG. 7  gradually decreases with a time point T 11  at which the amplitude value becomes a maximum value as a starting point, and gradually increases immediately after the amplitude value becomes zero at a time point T 12  to be the maximum value at a time point T 13 . The amplitude value is attenuated to a predetermined value that is less than the maximum value during the time period from a time substantially immediately after the time point T 13  to a time substantially immediately before a time point T 14 , is amplified to the maximum value at the time point T 14  again, and gradually decreases from a time immediately after the time point T 14  to be zero at a time point T 15 . Note that the aforementioned predetermined value may be properly set in accordance with, for example, a length of the end portion of the illuminating fiber  12  that is caused to swing by the actuator  15 , or the like. 
         [0068]    The first drive signal including the waveform as shown in  FIG. 7  is supplied to the X axis actuator of the actuator  15 , and the second drive signal that is obtained by the phase of the first drive signal being shifted by 90° is supplied to the Y axis actuator of the actuator  15 , whereby the end portion including the light exit surface of the illuminating fiber  12  is caused to swing with the point SA as the center. Further, in response to the swing of the illuminating fiber  12  as above, the locus of the illuminating light with which the surface of the object is irradiated changes in a sequence of  FIG. 4  to  FIG. 5  to  FIG. 8  to  FIG. 4  . . . .  FIG. 8  is a diagram for explaining an example, which differs from  FIG. 6 , of the locus in the circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned. 
         [0069]    More specifically, at the time point T 11  corresponding to the scan start timing for an object, the point YMAX that is the outermost point of the irradiation coordinates of the illuminating light in the surface of the object is irradiated with the illuminating light. Subsequently, as the amplitude values of the first and the second drive signals decrease from the time point T 11  to the time point T 12 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point YMAX as the starting point. Further, when the time point T 12  arrives, the position corresponding to the point SA on the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0070]    Further, as the amplitude values of the first and the second drive signals increase from the time point T 12  to the time point T 13 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the second spiral shape outward with the point SA as the starting point. Further, when the time point T 13  arrives, the point YMAX that is the outermost point of the irradiation coordinates of the illuminating light in the surface of the object is irradiated with the illuminating light (see  FIG. 5 ). 
         [0071]    Thereafter, in the time period from the time substantially immediately after the time point T 13  to the time substantially immediately before the time point T 14 , the irradiation coordinates of the illuminating light in the surface of the object displace so as to circle predetermined times along a locus in a circular shape with a radius R1 (&lt;RMAX) that corresponds to a distance between the point SA and a point Y 1  (see  FIG. 8 ). 
         [0072]    Subsequently, as the amplitude values of the first and the second drive signals decrease from the time point T 14  to the time point T 15 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point YMAX as the starting point. Further, when the time point T 15  arrives, the point SA in the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0073]    The controller  25  generates an image corresponding to one frame based on the respective color signals that are outputted from the detection unit  23  in a time period corresponding to a time period from the time point T 11  to the time point T 12 , and an image corresponding to one frame based on the respective color signals that are outputted from the detection unit  23  in a time period corresponding to a time period from the time point T 12  to the time point T 13 , during a time period from the time point T 13  until the time point T 14  and causes the monitor  4  to display the images, while the controller  25  keeps control for supplying the illuminating light to the illuminating fiber  12  from the light source unit  21 , and control for supplying the drive signal to the actuator  15  from the driver unit  22  respectively. Namely, the respective color signals that are outputted from the detection unit  23  during the time period corresponding to the time period from the time point T 13  to the time period T 14  do not contribute to generation of the images. 
         [0074]    According to the first modification described above, an action similar to the action in the time period from the time point T 13  to the time point T 14  described above is performed every fixed time period in which scanning for obtaining the image corresponding to two frames is completed. Therefore, according to the first modification described above, a timing relating to irradiation of the illuminating light to the object, and a timing relating to generation of the image corresponding to the return light from the object can be favorably synchronized, without control or the like that temporarily stops at least any one of swing of the illuminating fiber  12  and supply of the illuminating light to the illuminating fiber  12  being performed. As a result, according to the first modification described above, stability of the frame rate at the time of observation with use of the scanning endoscope can be enhanced as compared with the conventional system. 
         [0075]    Note that according to the present embodiment, instead of the drive signal including the waveform illustrated in  FIG. 3  or  FIG. 7 , a drive signal including a waveform as shown in  FIG. 9 , for example, may be supplied to the actuator  15 .  FIG. 9  is a diagram for explaining a second modification of the signal waveform of the drive signal that is supplied to the actuator provided in the scanning endoscope. 
         [0076]    Here, an amplitude value (a signal level) of the waveform of the drive signal illustrated in  FIG. 9  gradually decreases until a time point T 22  with a time point T 21  at which the amplitude value becomes a maximum value as a starting point, keeps a predetermined value in a time period from the time point T 22  until a time point T 23 , and gradually decreases from the time point T 23  to be zero at a time point T 24 . The amplitude value gradually increases from a time immediately after the amplitude value becomes zero at the time point T 24  until a time point T 25 , keeps a predetermined value in a time period from the time point T 25  to a time point T 26 , and gradually increases from the time point T 26  to be a maximum value at a time point T 27 . The amplitude value gradually decreases from the time point  27  until a time point T 28 , keeps a predetermined value in a time period from the time point T 28  to a time point T 29 , and gradually decreases from the time point T 29  to be zero at a time point T 30 . 
         [0077]    A first drive signal including the waveform as shown in  FIG. 9  is supplied to the X axis actuator of the actuator  15 , and a second drive signal obtained by a phase of the first drive signal being shifted by 90° is supplied to the Y axis actuator of the actuator  15 . Thereby, the end portion including the light exit face of the illuminating fiber  12  is caused to swing with the point SA as a center. Further, in response to the swing of the illuminating fiber  12  as above, the irradiation position of the illuminating light that is irradiated along the locus in the spiral shape of  FIG. 4  temporarily shifts to a locus in a circular shape illustrated in  FIG. 10 , and the irradiation position of the illuminating light that is irradiated along the locus in the spiral shape of  FIG. 5  temporarily shifts to a locus in a circular shape illustrated in  FIG. 11 .  FIG. 10  is a diagram for explaining an example, which differs from  FIG. 6  and  FIG. 8 , of the locus in the circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned.  FIG. 11  is a diagram for explaining an example, which differs from  FIG. 6 ,  FIG. 8  and  FIG. 10 , of the locus in the circular shape that is drawn when the virtual XY plane as in  FIG. 2  is scanned. 
         [0078]    More specifically, at the time point T 21  corresponding to a scan start timing for an object, the point YMAX that is the outermost point of the irradiation coordinates of the illuminating light in the surface of the object is irradiated with the illuminating light. Subsequently, as the amplitude values of the first and the second drive signals decrease from the time point T 21  to the time point T 22 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point YMAX as the starting point. Further, when the time point T 22  arrives, a position corresponding to a point Y 2  in the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0079]    In the time period from the time point T 22  until the time point T 23 , the irradiation coordinates of the illuminating light in the surface of the object displace so as to circle predetermined times along a locus in a circular shape with a radius R2 (&lt;RMAX) that corresponds to a distance between the point SA and the point Y 2  (see  FIG. 10 ). 
         [0080]    Thereafter, as the amplitude values of the first and the second drive signals decrease from the time point T 23  to the time point T 24 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point Y 2  as the starting point. Further, when the time point T 24  arrives, the position corresponding to the point SA in the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0081]    Further, as the amplitude values of the first and the second drive signals increase from the time period T 24  to the time period T 25 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the second spiral shape outward with the point SA as the starting point. Further, when the time point T 25  arrives, a position corresponding to a point Y 3  in the surface of the object is irradiated with the illuminating light (see  FIG. 5 ). 
         [0082]    In the time period from the time point T 25  until the time point T 26 , the irradiation coordinates of the illuminating light in the surface of the object displace so as to circle predetermined times along a locus in a circular shape with a radius R3 (&lt;RMAX) that corresponds to a distance between the point SA and the point Y 3  (see  FIG. 11 ). 
         [0083]    Thereafter, as the amplitude values of the first and the second drive signals increase from the time point T 26  to the time point T 27 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the second spiral shape outward with the point Y 3  as the starting point. Further, when the time point T 27  arrives, the position corresponding to the point YMAX in the surface of the object is irradiated with the illuminating light (see  FIG. 5 ). 
         [0084]    Subsequently, as the amplitude values of the first and the second drive signals decrease from the time point T 27  to the time point T 28 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point YMAX as the starting point. Further, when the time point T 28  arrives, the position corresponding to the point Y 2  in the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0085]    In the time period from the time point T 28  until the time point T 29 , the irradiation coordinates of the illuminating light in the surface of the object displace so as to circle a predetermined times along the locus in the circular shape with the radius R2 (&lt;RMAX) that corresponds to the distance between the point SA and the point Y 2  (see  FIG. 10 ). 
         [0086]    Thereafter, as the amplitude values of the first and the second drive signals decrease from the time point T 29  to the time point T 30 , the irradiation coordinates of the illuminating light in the surface of the object displace in such a manner as to draw the locus in the first spiral shape inward with the point Y 2  as the starting point. Further, when the time point T 30  arrives, the position corresponding to the point SA in the surface of the object is irradiated with the illuminating light (see  FIG. 4 ). 
         [0087]    The controller  25  generates an image of a first half portion based on the respective color signals, which are outputted from the detection unit  23  in a time period corresponding to a time period from the time point T 21  to the time point T 22 , during a time period from the time point T 22  until the time point T 23 , generates an image of a latter half portion based on the respective color signals, which are outputted from the detection unit  23  in a time period corresponding to a time period from the time point T 23  to the time point T 24 , during a time period from the time point T 25  until the time point T 26 , and further generates an image corresponding to one frame obtained by the image of the first half portion and the image of the latter half portion being synthesized during the time period from the time point T 25  until the time point T 26  to cause the monitor  4  to display the image corresponding to one frame, while the controller  25  keeps control for supplying the illuminating light to the illuminating fiber  12  from the light source unit  21 , and control for supplying the drive signal to the actuator  15  from the driver unit  22  respectively. Namely, the respective color signals that are outputted from the detection unit  23  during the time period corresponding to the time period from the time point T 23  to the time point T 24 , and during the time period from the time point T 25  until the time point T 26  do not contribute to generation of the image. 
         [0088]    Further, the controller  25  generates an image of a first half portion based on the respective color signals, which are outputted from the detection unit  23  in a time period corresponding to a time period from the time point T 24  to the time point T 25 , during a time period from the time point T 25  until the time point T 26 , generates an image of a latter half portion based on the respective color signals, which are outputted from the detection unit  23  in a time period corresponding to a time period from the time point T 26  to the time point T 27 , during a time period from the time point T 28  until the time point T 29 , and further generates an image corresponding to one frame obtained by the image of the first half portion and the image of the latter half portion being synthesized during the time period from the time T 28  until the time T 29  to cause the monitor  4  to display the image corresponding to one frame, while the controller  25  keeps control for supplying the illuminating light to the illuminating fiber  12  from the light source unit  21 , and control for supplying the drive signal to the actuator  15  from the driver unit  22  respectively. Namely, the respective color signals that are outputted from the detection unit  23  during the time period corresponding to the time period from the time point T 28  to the time point T 29  do not contribute to generation of the image. 
         [0089]    According to the second modification described above, an action similar to any one of the action in the time period from the time point T 22  to the time point T 23 , the action in the time period from the time point T 25  to the time period T 26 , and the action in the time period from the time point T 28  to the time point T 29  is performed every predetermined time period provided in the process of scanning for obtaining the image corresponding to one frame. Therefore, according to the second modification described above, the timing relating to irradiation of the illuminating light to the object, and the timing relating to generation of the image corresponding to the return light from the object can be favorably synchronized without control or the like that temporarily stops at least any one of swing of the illuminating fiber  12  and supply of the illuminating light to the illuminating fiber  12  being performed. As a result, according to the second modification described above, stability of the frame rate at the time of observation with use of the scanning endoscope can be enhanced as compared with the conventional system. 
         [0090]    Note that according to the present embodiment, instead of the drive signal including the waveform illustrated in  FIG. 3 ,  FIG. 7  or  FIG. 9 , a drive signal including a waveform as shown in  FIG. 12 , for example, may be supplied to the actuator  15 .  FIG. 12  is a diagram for explaining a third modification of the signal waveform of the drive signal that is supplied to the actuator provided in the scanning endoscope. 
         [0091]    Here, a first drive signal including the waveform as shown in  FIG. 12  is supplied to the X axis actuator of the actuator  15 , and a second drive signal that is obtained by a phase of the second drive signal being shifted by 90° is supplied to the Y axis actuator of the actuator  15 . Thereby, in each of a time period from a time point T 41  until a time point T 42 , and a time period from a time point T 43  until a time point T 44 , the end portion including the light exit face of the illuminating fiber  12  is caused to swing in such a manner as to draw a locus in a spiral shape with the point SA as a center, namely, in a sequence of the locus in the second spiral shape as illustrated in  FIG. 5  to the locus in the first spiral shape as illustrated in  FIG. 4 . 
         [0092]    Note that according to the waveform of the drive signal shown in  FIG. 12 , a maximum amplitude value in the time period from the time point T 43  until the time point T 44  is set to be smaller as compared with a maximum amplitude value in the time period from the time point T 41  until the time point T 42 . Therefore, according to the waveform of the drive signal shown in  FIG. 12 , when a coordinate position of an outermost point of the irradiation coordinates of the illuminating light in the time period from the time point T 41  until the time point T 42  is set as a point YMAX1, and a coordinate position of an outermost point of the irradiation coordinates of the illuminating light in the time period from the time point T 43  until the time point T 44  is set as a point YMAX2, for example, the relation of YMAX1&gt;YMAX2 is established. 
         [0093]    The controller  25  generates an image corresponding to two frames based on the respective color signals, which are outputted from the detection unit  23  in the time period corresponding to the time period from the time point T 41  to the time point T 42 , during the time period from the time point T 43  until the time point T 44  to cause the monitor  4  to display the image, while the controller  25  keeps control for supplying the illuminating light to the illuminating fiber  12  from the light source unit  21 , and control for supplying the drive signal to the actuator  15  from the driver unit  22 . Namely, the respective color signals that are outputted from the detection unit  23  during the time period corresponding to the time period from the time point T 43  to the time period T 44  do not contribute to generation of the image. 
         [0094]    According to the third modification described above, an action similar to the action in the time period from the time point T 43  to the time point T 44  that is described above is performed every fixed time period in which scanning for obtaining the image corresponding to two frames is completed. Therefore, according to the third modification described above, the timing relating to irradiation of the illuminating light to the object, and the timing relating to generation of the image corresponding to the return light from the object can be favorably synchronized, without control or the like that temporarily stops at least any one of swing of the illuminating fiber  12  and supply of the illuminating light to the illuminating fiber  12  being performed. As a result, according to the third modification described above, stability of the frame rate at the time of observation with use of the scanning endoscope can be enhanced as compared with the conventional system. 
         [0095]    Note that according to the present embodiment, instead of the drive signal including the waveform illustrated in  FIG. 3 ,  FIG. 7 ,  FIG. 9  or  FIG. 12 , a drive signal including a waveform as shown in  FIG. 13 , for example, may be supplied to the actuator  15 .  FIG. 13  is a diagram for explaining a fourth modification of the signal waveform of the drive signal that is supplied to the actuator provided in the scanning endoscope. 
         [0096]    Here, a first drive signal including the waveform as shown in  FIG. 13  is supplied to the X axis actuator of the actuator  15 , and a second drive signal that is obtained by a phase of the second drive signal being shifted by 90° is supplied to the Y axis actuator of the actuator  15 . Thereby, in a time period from a time point T 51  until a time point T 52 , the end portion including the light exit face of the illuminating fiber  12  is caused to swing in such a manner as to draw a locus in a spiral shape with the point SA as a center, namely, in a sequence of the locus in the second spiral shape as illustrated in  FIG. 5  to the locus in the first spiral shape as illustrated in  FIG. 4 . 
         [0097]    Further, the first drive signal including the waveform as shown in  FIG. 13  is supplied to the X axis actuator of the actuator  15 , and the second drive signal obtained by the phase of the second drive signal being shifted by 90° is supplied to the Y axis actuator of the actuator  15 . Thereby, in a time period from a time point T 53  until a time point T 54 , the end portion including the light exit face of the illuminating fiber  12  is caused to swing in such a manner as to draw a locus in a circular shape with the point SA as the center. 
         [0098]    Note that according to the waveform of the drive signal shown in  FIG. 13 , a maximum amplitude value (a signal level) in the time period from the time point T 53  until the time point T 54  is set to include a fixed value that is larger than zero and smaller as compared with a maximum amplitude value in the time period from the time point T 51  until the time point T 52 . Therefore, according to the waveform of the drive signal shown in  FIG. 13 , in the time period from the time point T 53  until the time point T 54 , the end portion including the light exit face of the illuminating fiber  12  may be caused to swing along the locus in the circular shape of  FIG. 8 , may be caused to swing along the locus in the circular shape of  FIG. 10 , or may be caused to swing along the locus in the circular shape of  FIG. 11 , for example. 
         [0099]    The controller  25  generates an image corresponding to two frames based on the respective color signals, which are outputted from the detection unit  23  in the time period corresponding to the time period from the time point T 51  to the time point T 52 , during the time period from the time point T 53  until the time point T 54  to cause the monitor  4  to display the image, while the controller  25  keeps control for supplying the illuminating light to the illuminating fiber  12  from the light source unit  21 , and control for supplying the drive signal to the actuator  15  from the driver unit  22 , respectively. Namely, the respective color signals that are outputted from the detection unit  23  during the time period corresponding to the time period from the time point T 53  to the time point T 54  do not contribute to generation of the image. 
         [0100]    According to the fourth modification described above, an action similar to the action in the time period from the time point T 53  to the time point T 54  that is described above is performed every fixed time period in which scanning for obtaining the image corresponding to two frames is completed. Therefore, according to the fourth modification described above, the timing relating to irradiation of the illuminating light to the object, and the timing relating to generation of the image corresponding to the return light from the object can be favorably synchronized without control or the like that temporarily stops at least any one of swing of the illuminating fiber  12  and supply of the illuminating light to the illuminating fiber  12  being performed. As a result, according to the fourth modification described above, stability of the frame rate at the time of observation with use of the scanning endoscope can be enhanced as compared with the conventional system. 
         [0101]    The present invention is not limited to the embodiment and the modifications described above, and various changes and applications can be made within the range without departing from the gist of the invention, as a matter of course.