referring to the attached drawings , description will be given below on embodiments of the invention . fig1 shows a side view of an ultrasonic probe in a first embodiment of the invention . in case a speed reducing mechanism is provided on a rotating shaft of a motor 1 or on the motor 1 , which is fixed on a frame of the ultrasonic probe , an output shaft of the speed reducing mechanism ( hereinafter referred as “ a rotating shaft 7 ”) penetrates the frame 5 of the probe , and it is rotated in normal or reverse direction at a predetermined angle in an acoustic coupling liquid 4 to promote propagation of ultrasonic waves sealed by oil - seal or window by means of a driving electric signal from an ultrasonic diagnostic apparatus main unit ( not shown ), which is connected by an ultrasonic probe . specifically , a first arm 6 with its one end fixed on a rotating shaft 7 , i . e . a first shaft member , is rotated in normal or reverse direction at a predetermined angle around the rotating shaft 7 along with the rotation of the rotating shaft 7 , resulting in swinging movement . a coupling shaft 9 is fixed on the other end of the first arm 6 , and a second arm 8 is rotatably connected with a coupling shaft 9 . at the tip of the other end of the second arm 8 , an element unit 2 with an ultrasonic element is disposed , which can convert electric signals and ultrasonic signals with each other . between the ultrasonic element and the ultrasonic diagnostic apparatus main unit , electric signals are transmitted via a flexible printed circuit board ( not shown ). on the coupling shaft 9 , the first arm 6 and the second arm 8 are rotatably connected respectively . the coupling shaft 9 is fixed either on the first arm 6 or on the second arm 8 so that each arm is rotatable . a lengthwise long groove 11 is formed between a fixed end where the element unit 2 of the second arm 8 is mounted and the coupling shaft 9 , and a fixing shaft 10 , which is a second shaft member fixed on the probe frame 5 , is engaged with the groove 11 . the width of the groove 11 is approximately the same as diameter of the engaging unit of the fixed shaft 10 . it is designed as a lengthwise long groove in a direction of the length of the second arm 8 . the length of the groove would suffice if the second arm 8 can move when the rotating shaft 7 is rotated in normal or reverse direction . with the rotation in normal or reverse direction of the first arm 6 , the second arm 8 can be moved in the direction of the length along the lengthwise long groove 11 . the first arm 6 fixed on the rotating shaft 7 of the motor 1 rotates the second arm 8 , which is rotatably fixed by the coupling shaft 9 due to the swinging movement caused by the rotation in normal or reverse direction of the rotating shaft 7 with the fixed shaft 10 as fulcrum , and the element unit 2 performs swinging movement with the fixed shaft 10 as fulcrum . in this case , the element unit 2 mounted on the second arm 8 moves along the groove 11 , which is engaged with the fixing shaft 10 , the second arm 8 is engaged with the fixed shaft 10 in the direction of length when the first arm 6 is rotated along with the rotation of the rotating shaft 7 due to the movement of the coupling shaft 9 . as a result , the locus , along which the element unit 2 moves , is different from the locus when the coupling shaft 9 of the second arm 8 is used as the rotating shaft for fixing . fig2 is a drawing , schematically showing operation of the swinging mechanism , which comprises a first arm 6 and a second arm 8 , according to the present invention . referring to fig2 , detailed description will be given below on the swinging rotation . when the rotating shaft 7 of the motor is rotated in normal direction or in reverse direction , the first arm 6 with its one end fixed on the rotating shaft 7 is also rotated in normal direction or in reverse direction . it is supposed here that the other end ( not fixed on the rotating shaft 7 ) of the first arm 6 is at a point a , that the rotating shaft 7 is a point b , and that the fixed shaft 10 engaged in the groove 11 of the second arm 8 is a point c . then , swinging is performed so that a triangular shape is always formed by the points a , b and c . according to the direction of the rotation of the coupling shaft 9 , the coupling shaft 9 is swung from fig2 ( a ) to fig2 ( b ), or from fig2 ( a ) to fig2 ( c ). as a result , the larger the rotation angle of the rotating shaft 7 of the motor is , the more the coupling shaft 9 , which is an operating point of the second arm 8 , is rotated so that the element unit 2 is extended in the length direction . the locus of the moving of the element unit 2 will be the locus of the curvature , which is different from the case where the coupling shaft 9 of the second arm 8 is the center of the swinging . thus , by using a simple swinging mechanism , the element unit 2 having the ultrasonic element can be moved with larger curvature . accordingly , even when diagnosis is made on a relatively flat affected region of the patient , the adhesiveness with the ultrasonic probe can be increased . fig3 is a drawing to explain the principle of the swinging mechanism , which comprises the first arm 6 and the second arm 8 . referring to fig3 , detailed description will be given on the locus of the element unit 2 when the rotating shaft 7 of the motor is rotated in normal direction or in reverse direction . coordinates x - y are taken with a fixed shaft 10 ( point c ) as the origin , and it is supposed that a distance between the motor rotating shaft 7 ( point b ) and the coupling shaft 9 ( point a ) of the first arm 6 is l 1 , that a distance between the coupling shaft 9 ( point a ) and the tip ( point d ) of the element unit 2 of the second arm 8 is l 2 , that a distance between the motor shaft 7 ( point b ) and the fixed shaft 10 ( point c ) is l 3 , and that l 2 is sufficiently longer than l 1 and l 3 . when the first arm 6 is tilted at a swinging angle of θ with respect to y axis , the coordinates of the point a , which is the connecting point of the first arm 6 and the second arm 8 is given as : and the second arm 8 will be on a straight line : in the coordinates x - y with the fixed shaft 10 ( point c ) as the origin . therefore , a distance dl from the origin ( point c ) to the connecting point ( point a ) of two arms is given as : √{ square root over (( l 1 × sin θ )×( l 1 × sin θ )+(− l 1 × cos θ − l 3 ) (− l 1 × cos θ l 3 ))}{ square root over (( l 1 × sin θ )×( l 1 × sin θ )+(− l 1 × cos θ − l 3 ) (− l 1 × cos θ l 3 ))}{ square root over (( l 1 × sin θ )×( l 1 × sin θ )+(− l 1 × cos θ − l 3 ) (− l 1 × cos θ l 3 ))}{ square root over (( l 1 × sin θ )×( l 1 × sin θ )+(− l 1 × cos θ − l 3 ) (− l 1 × cos θ l 3 ))}=√{ square root over ( l 1 × l 1 + l 3 × l 3 + 2 cos θ × l 3 × l 1 )} therefore , the coordinates of the point d , which is the tip of the second arm 8 , is given as : fig4 is a drawing to show the locus of the tip point d of the second arm 8 when it is supposed that l 1 = 30 mm , l 2 = 100 mm and l 3 = 15 mm , and that the first arm 6 is swung up to ± 45 ° from y axis . it shows a convex type locus with larger curvature . fig5 shows the locus of the tip point d of the second arm 8 in case it is supposed that l 1 = 30 mm , l 2 = 100 mm , and l 3 = 30 mm , and that the first arm 6 is swung from y axis up to an angle of ± 45 °. it shows an approximately flat locus although it is slightly concaved . [ 0047 ] the locus of the tip of the second arm 8 shown in fig4 and fig5 is merely an example . by adjusting the length of each of l 1 , l 2 and l 3 respectively , it is possible to have the locus of the tip point d of the second arm 8 as desired . [ 0048 ] fig6 shows the locus of the tip point d of the second arm when it is supposed that l 1 = 30 mm , l 2 = 100 mm , and l 3 = 26 mm , and that the first arm 6 is swung from y - axis up to an angle of ± 45 °. as shown in this figure , the displacement in the direction of y - axis can be set at about 0 . 1 mm , and the element unit 2 can be moved in approximately horizontal direction . also , in case a distance from the point a to the point b is made equal to the distance between the point b and the point c in fig3 , the triangle abc can be formed as an isosceles triangle at all times . if the triangle abc is an isosceles triangle , there exists a relation : 2 ∠ acb = θ . with respect to the rotation angle θ of the first arm 6 , the rotation angle of the element unit 2 is tilted at an angle of one half at all times . thus , the swinging angle of the ultrasonic element can always be maintained at a relation of 2 : 1 to the rotation angle of the motor . if the rotation angle of the motor is swung at a constant angle , the ultrasonic element can always have uniform swinging angle . fig7 is a side view of an ultrasonic probe in the second embodiment of the invention . instead of the engagement of the fixed shaft 10 with the groove 11 of the second arm 8 as shown in fig1 , a slide bearing 12 is mounted on the second arm 8 to be connected with the fixed shaft 10 to ensure smooth moving of the second arm 8 in this embodiment . also , it may be so designed that two or more bearings are provided at the tip of the fixed shaft 10 to be engaged with the groove 11 in the embodiment shown in fig1 in order to ensure smooth moving . in this case , it is desirable to have such an arrangement that shakiness can be absorbed by means of a spring to overcome the variation of groove width caused by fabrication accuracy of the groove 11 by two or more bearings . fig8 shows the condition of the connection of the element unit in the first embodiment of the ultrasonic probe according to the invention . in this embodiment , the element unit 2 with the ultrasonic element attached on the tip of the second arm 8 is rotatably mounted on the tip of the second arm 8 via an element rotating shaft 13 , and a guiding shaft 14 mounted on the element unit 2 is engaged with a groove type rail 15 mounted on the probe frame 5 or on a window 3 . the element unit 2 can move along the rail 15 by means of the guiding shaft 14 , and the ultrasonic element to transmit and receive the ultrasonic waves can be tilted in any direction as desired with respect to the body of the patient . also , by this arrangement , the ultrasonic element can always be kept in parallel to the window 3 . as a result , the ultrasonic waves emitted from the ultrasonic element can be always projected perpendicularly to the surface of the window 3 . fig9 shows a connecting structure of the element unit of the ultrasonic probe shown in fig8 . the guiding shaft 14 has two guiding shafts . one of the guiding shafts is fixed on the element unit 2 , and the other guiding shaft is fixed on a spring 16 , and the groove type rail 15 and the two guiding shafts 14 are engaged with each other by resilient force of the spring 16 . as a result , the shakiness between the groove of the rail 15 and the guiding shaft 14 caused by fabrication accuracy of the component parts can be absorbed . this contributes to the reduction of vibration and noise during operation and is also helpful to stabilize the tilting angle of the element unit 2 during the swinging operation . fig1 is a drawing to show connection of the element unit in the second embodiment of the ultrasonic probe of the invention . a convex type rail 15 is placed between two guiding shafts 14 to support the element unit 2 . by this arrangement , ultrasonic waves can be projected perpendicularly to the surface of the window 3 . compared with the case where concave grooves are formed on the window 3 or on the probe frame 5 , this makes it easier to fabricate the rail 15 by mechanical fabrication or by die molding . the number of the guiding shafts 14 is not limited to two , and three or more guiding shafts 14 may be used to support the element unit 2 . fig1 is a drawing to show a connecting structure in the first embodiment of the element unit of the ultrasonic probe shown in fig1 . the guiding shafts 14 comprise two guiding shafts . one of the guiding shafts is fixed on the element unit 2 , and the other of the guiding shafts is fixed on the spring 16 . by resilient force of the spring 16 , convex portion of the rail 15 inserted between the two guiding shafts is pressed together . by this arrangement , the shakiness of the convex type rail 15 and the two guiding shafts 14 originated from the causes such as the lack of fabrication accuracy can be absorbed by the spring 16 , and vibration and noise during operation can be reduced . at the same time , tilting angle of the element unit 2 can be stabilized during swinging operation . also , when the rail 15 is manufactured by mechanical fabrication or by die molding , manufacturing procedure will be much easier compared with the case where the groove should be fabricated . fig1 is a drawing to show a connecting structure in the second embodiment of the element unit of the ultrasonic probe shown in fig1 . in addition to the embodiment shown in fig1 , bearings 17 are mounted at forward ends of two guiding shafts 14 , and the guiding shafts 14 are pressed together to the convex part of the rail 15 via the bearings 17 by resilient force of the spring 16 . by this arrangement , sliding friction resistance between the rail 15 and the guiding shaft 14 can be decreased , and this contributes to the reduction of the burden on the motor 1 to be driven , and smooth movement can be accomplished . instead of the use of the bearings 17 , if low - friction materials such as teflon resin may be used at the forward ends of the two guiding shafts 14 to slide over the convex portion of the rail 15 , the same effects can be attained . if necessary , without providing the spring 16 , only the bearings or the low friction materials such as teflon resin may be used . fig1 is a drawing to show a connecting structure in the third embodiment of the element unit of the ultrasonic probe shown in fig1 . an elastic member 18 is disposed at the tips of two guiding shafts 14 , and the elastic members 18 are pressed to the convex portion of the rail 15 . by this arrangement , even when there is variation in thickness of the convex portion squeezed by the guiding shafts 14 of the convex rail 15 , the shakiness caused can be absorbed by the elastic members 18 , and it is possible to reduce vibration noise and to accomplish the movement with lower load variation . one of the two guiding shafts 14 may be used as the elastic member 18 . fig1 is a side view of an ultrasonic probe in the third embodiment of the invention . the first arm 6 is rotatably mounted around the fixed shaft 19 , which is a first shaft member . on the rotation shaft 7 fixed on the motor 1 , a third arm 20 is mounted , and it is rotated in normal or reverse direction at a predetermined angle around the rotating shaft 7 in association with the normal or reverse rotation of the rotating shaft 7 . on the third arm 20 , a first driving shaft 21 and a second driving shaft 22 are fixed . the second driving shaft 22 may be disposed along a line , which connects the driving shaft 21 with the rotating shaft 7 . fig1 shows the case where it is disposed on the axis of the rotating shaft 7 . specifically , the first driving shaft 21 , the second driving shaft 22 and the coupling shaft 9 are always positioned along the same straight line . thus , the rotation of the first arm 6 in reverse direction can be avoided when the first driving shaft 21 is rotated . the rotating shaft 7 , the third arm 20 , the first driving shaft 21 , and the second driving shaft 22 make up together a second shaft member . the first driving shaft 21 and the second driving shaft 22 are engaged with the groove 11 , which is disposed on the second arm 8 . the width of the groove 11 is approximately the same as diameter of the first driving shaft 21 and the second driving shaft 22 , and it is formed lengthwise long along the direction of the length of the second arm 8 . by normal or reverse rotation of the rotating shaft 7 , the second arm 8 can be moved in swinging movement via the first driving shaft 21 and the second driving shaft 22 . the first arm 6 , the coupling shaft 9 , and the second arm 8 make up together a linking mechanism . when the rotating shaft 7 is rotated in normal or reverse direction via this linking mechanism , it can be moved in swinging movement with a radius curvature longer than the length of the second arm 8 . in this case , the third arm 20 , the first drive shaft 21 and the second drive shaft 22 may be provided separately or may be integrated together . fig1 a to fig1 c represent the drawings , each showing the swinging mechanism , which comprises the first arm 6 and the second arm 8 at the rightward tilted position , at the central position , and at the leftward tilted position in the third embodiment respectively . referring to fig1 a to fig1 c , detailed description will be given below on the swinging rotation . when the rotating shaft 7 is rotated in normal or reverse direction , the third arm 20 with its one end fixed on the rotating shaft 7 is also rotated in normal or reverse direction . fig1 a shows a condition where the rotating shaft 7 is rotated and the element unit 2 is tilted rightward . here , if it is supposed that the center of the rotating shaft 7 is the point a , when the rotating shaft 7 is rotated , the third arm 20 fixed on the rotating shaft 7 is rotated around the point a . a fixed shaft 19 is disposed at a certain distance from the rotating shaft 7 . if it is supposed that the center of the fixed shaft 19 is the point b , one end of the first arm 6 is rotatably held around the point b . the other end of the first arm 6 is rotatably connected with the second arm 8 via the coupling shaft 9 . if it is supposed that the center of the coupling shaft 9 is the point c , it is swung so that the point a , the point b and the point c always form a triangle . on the second arm b , a lengthwise long groove 11 is provided in the direction of the length . the tips of the first driving shaft 21 and the second driving shafts 22 provided on the third arm 20 are engaged with this groove 11 , and the second arm 8 can move in the length direction . the second arm 8 is always swung in such direction that a triangle is formed by the point a , the point b , and the point c . according to the direction of the rotation of the rotating shaft 7 , it is swung as shown from fig1 a , to fig1 b and to fig1 c . the bigger the rotation angle of the rotating shaft 7 of the motor is , the more the second arm 8 is extended and the element unit 2 is rotated in the length direction by the coupling shaft 9 , which is an operating point of the second arm 8 . here , by defining the first driving shaft 21 as a point d , and when the first driving shaft 21 and the second driving shaft 22 are engaged with the groove 11 and are rotated , the second arm 8 is positioned with its lower end at the point c , and the tilting is determined by the point c and the point d , and swinging is performed . as a result , the moving locus of the element unit 2 will be a locus with a larger curvature than the case where the center of the swinging is on the coupling shaft 9 of the second arm 8 . fig1 is a drawing to explain operation of a swinging mechanism , which has a first arm 6 and a fourth arm 23 in the fourth embodiment of the invention . referring to fig1 , detailed description will be given on the swinging rotation . specifically , in the fourth embodiment , it is not an arrangement where the groove 11 is provided on the second arm 8 as described above and it is swung , but it is so arranged that a first sliding shaft 24 , a second sliding shaft 25 , and a third sliding shaft 26 are provided on the third arm 20 , and the fourth arm 23 is squeezed between them . the fourth arm 23 can be swung by rotating the third arm 20 in normal or reverse direction . as a result , the moving locus of the element unit 2 will be a locus having a larger curvature than the case where the coupling shaft 9 of the fourth arm 23 is set as the center of swinging . in this case , it may be so arranged that the first sliding shaft 24 , the second sliding shaft 25 , and the third sliding shaft 26 may be brought into contact with the fourth arm 23 by means of bearing or resin with low friction resistance to reduce the sliding resistance with the fourth arm 23 . further , in order to prevent the shakiness , it may be so designed that the third sliding shaft 26 is pulled toward the first sliding shaft 24 and the second sliding shaft 25 by means of spring or elastic material . fig1 is a side view of the ultrasonic probe in the fifth embodiment of the invention , and a slide bearing 27 engaged with the fourth arm 23 is mounted on the rotating shaft 7 . in association with normal rotation or reverse rotation of the rotating shaft 7 , the fourth arm 23 is swung inside of the slide bearing 27 . fig1 is a side view of the ultrasonic probe in the sixth embodiment of the invention , and fig1 is a side view of the ultrasonic probe in the seventh embodiment of the invention . in fig1 , position detecting means 28 for detecting rotation angle of the first arm 6 is disposed inside the probe frame 5 . fig1 shows an arrangement where the fixed shaft 19 and the arm 6 are integrated and are rotated together , and it penetrates the frame 5 rotatably , and position detecting means 29 is provided outside the probe frame 9 to detect a rotation angle of the first arm 6 via a fixed shaft 19 . it is supposed here that the center of the rotating shaft 7 is the point a , the center of the fixed shaft 19 is the point b , and the center of the coupling shaft 9 is the point c . then , by arranging that a distance from the point a to the point b is the same as the distance between the point b and the point c , the triangle abc is always formed as an isosceles triangle . if the third arm 20 is rotated by an angle θ , the tip of the second arm 8 is rotated by an angle θ around a virtual rotation center , and the first arm 6 is rotated at an angle of 2θ . that is , by detecting the rotation angle of the first arm 6 , which is rotated at an angle twice as large as the rotation angle of the rotation shaft 7 , i . e . a tilting angle of the element unit 2 by means of the position detecting means 28 or 29 , the tilting angle of the element unit 2 can be detected with high accuracy . as the position detecting means 28 and 29 , an optical encoder or a magnetic encoder or a potentiometer can be used . as the connecting structure of the element unit 2 in the third to the seventh embodiments as given above , the connecting structure as shown in fig8 to fig1 can be applied . as described above , according to the present invention , an apparent rotation radius of the moving of the ultrasonic element can be set to a larger value , and this makes it possible to design the ultrasonic element in smaller size . also , as described above , when the ultrasonic element is moved by using wire and pulley as in the conventional example given above , there is a region , which comes out beyond both ends from the scanning area as it is necessarily caused by the diameter of the pulley , while , in the arrangement as given above , such problem can be actually eliminated . this contributes to the elimination of dead space , which causes when accurate diagnosis must be performed on the body of the patient . the ultrasonic element as given above may be a single element , and it may be a mechanical ultrasonic probe , which mechanically scans by means of swinging mechanism . if the ultrasonic element is an electronic scanning type ultrasonic element and if the ultrasonic element is arranged so that electronic scanning is performed in a direction perpendicularly crossing the mechanical swinging direction , it is possible to obtain an ultrasonic probe , which can acquire three - dimensional ultrasonic image through scanning by electronic scanning and the scanning by mechanical swinging . as described above , the present invention provides such effects that a mechanism can be accomplished , by which it is possible to have higher radius of curvature so that the contact portion of the probe will be in such shape as to ensure close contact with the body of the patient . the invention provides an ultrasonic probe to acquire ultrasonic tomogram by mechanically swinging the ultrasonic element and a small type ultrasonic probe with higher convenience as a hand - carried ultrasonic probe , and the invention can be applied on mechanical ultrasonic probe or on ultrasonic probe suitable for three - dimensional investigation .
the invention discloses a technique , by which a suitable radius of curvature can be obtained so that small type ultrasonic probe will be closely fitted to human body and by which an ultrasonic probe adaptable for human superficial tissues can be provided . according to this technique , the invention provides a frame 5 to constitute a part of a cubicle , a motor 1 fixed on said frame , a first arm 6 with one end fixed on a rotating shaft 7 of said motor , and a second arm 8 with one end rotatably coupled with the other end of said first arm via a coupling shaft 9 and with the other end having an ultrasonic element mounted thereon , said second arm has a lengthwise long groove 11 and is slidably engaged with the fixed shaft of said frame in the direction of length , a length from an end of said second arm where said ultrasonic element is mounted on said coupling shaft is designed to be longer than the length from said rotating shaft to said coupling shaft , and further , to be longer than the length from said rotating shaft to said fixed shaft , and a swinging mechanism comprising said first arm and said second arm is disposed in said cubicle surrounded by an ultrasonic window and by said frame and is sealed with an acoustic coupling liquid .