text: referring to fig2 to fig5 central magnetic teeth 11a are formed along the center line in a stationary body 11 made of magnetic material . further , side magnetic teeth 11b1 and 11b2 are formed at both sides of the central magnetic teeth 11a in the stationary body 11 , and are aligned with each other in the direction perpendicular to the moving direction a of a movable body 12 . the pitches of the side magnetic teeth 11b1 and 11b2 are equal to the pitch p of the central magnetic teeth 11a . the side magnetic teeth 11b1 and 11b2 are shifted in phase by a half of the pitch ( 1 / 2p ) from the central magnetic teeth 11a . the length l1 of the central magnetic teeth 11a is twice as large as that l2 of the side magnetic teeth 11b1 and 11b2 . the movable body 12 includes three iron cores 13 , 14 and 15 , spacers 16 and 17 interposed between the iron cores 13 , 14 and 15 , a permanent magnet 18 mounted on the iron cores 13 , 14 and 15 , a backplate 19 made of magnetic material , and coils 20 and 21 . the iron cores 13 , 14 and 15 include four downwardly extending magnetic poles 13a to 13b , 14a to 14d and 15a to 15d , respectively . the magnetic poles 13a , 14a and 15a ; 13b , 14b and 15b ; 13c , 14c and 15c ; and 13d , 14d and 15d are aligned with each other in the direction perpendicular to the moving direction a of the movable body 12 . the spacers 16 and 17 are made of non - magnetic material . the iron cores 13 , 14 and 15 are magnetically separated from each other by the spacers 16 and 17 . the one coil 20 is wound on the magnetic poles 13a , 14a and 15a , and 13d , 14d and 15d . the winding directions of the one coil 20 are opposite on the magnetic poles 13a to 15a and 13d to 15d . the other coil 21 is wound on the magnetic poles 13b , 14b and 15b , and 13c , 14c and 15c . the winding directions of the other coil 21 are opposite on the magnetic poles 13b to 15b and 13c to 15c . the permanent magnet 18 consists of three magnet regions 18a , 18b and 18c which are magnetically intercepted from each other by nonmagnetic regions 18d and 18e , as shown in fig5 . the magnet regions 18a and 18c are magnetized in the same polarities , as shown in fig4 . the magnet region 18b is oppositely magnetized in the polarities to the magnet regions 18a and 18c . the magnet regions 18a and 18c are superimposed on the iron cores 13 and 15 , respectively , while the magnet region 18b is superimposed on the center iron core 14 . as shown in fig5 the thickness t 1 of the center iron core 14 is twice as large as that t 2 of the iron cores 13 and 15 . magnetic fluxes from the permanent magnet 18 flow along magnetic paths as shown by dash lines in fig5 . the one magnetic path is formed by the one side iron core 15 , air gap g , the stationary body 11 , the center iron core 14 and the backplate 19 . the other magnetic path is formed by the backplate 19 , the other side iron core 13 , air gap g , the stationary body 11 and the center iron core 14 . the row of the central magnetic teeth 11a of the stationary body 11 faces directly towards the central iron core 14 of the movable body 12 , while the rows of the side magnetic teeth 11b1 and 11b2 of the stationary body 11 face directly towards the side iron cores 13 and 15 of the movable body 12 , respectively . the magnetic poles 13a to 15a and 13d to 15d on which the one coil 20 is wound , are shifted from each other in phase by a half of pitch ( 1 / 2p ) with respect to the side magnetic teeth 11b1 , 11b2 or central magnetic teeth 11a of the stationary body 11 . similarly , the magnetic poles 13b to 15b and 13c to 15con which the other coil 21 is wound , are shifted from each other in phase by a half of pitch ( 1 / 2p ) with respect to the side magnetic teeth 11b1 , 11b2 or central magnetic teeth 11a of the stationary body 11 . further , the magnetic poles 13a to 15a , 13b to 15b , 13c to 15c and 13d to 15d are so arranged that they are shifted by a quarter of the pitch ( 1 / 4p ) in phase from one another with respect to the magnetic teeth 11a or 11b1 , 11b2 of the stationary body 11 , in the order of the magnetic poles 13a to 15a , 13b to 15b , 13d to 13d , and 13c to 15c . next , there will be described operations of the above described linear pulse motor with reference to fig6 to fig9 . a positive dc current + i is supplied to the one coil 20 for a predetermined time . induced magnetic fluxes by the coil 20 are added to the magnetic flux φ from the permanent magnet 18 in the magnetic poles 13a , 15a and 14d , while they are cancel the magnetic flux from the permanent magnet in the magnetic poles 14a , 13d and 15d . magnetic pull forces act between the adjacent ones of the side magnetic teeth 11b1 , 11b2 of the stationary body 11 and the magnetic poles 13a , 15a of the movable body 12 , and between the adjacent one of the central magnetic teeth 11a of the stationary body 11 and the magnetic pole 14d of the movable body 12 , as shown by the dotted lines in fig6 a . fig6 b shows the pole surfaces ( hatched ) of the magnetic poles on which the magnetic pull forces act . the movable body 12 steps forwards by 1 / 4p so as to take the position shown in fig6 a . next , at the same time when the one coil 20 is deenergized , the positive dc current + i is supplied to the other coil 21 for the predetermined time . induced magnetic fluxes by the coil 21 are added to the magnetic flux φ from the permanent magnet 18 in the magnetic poles 13b , 15b and 14c , while they are cancelled with it in the magnetic poles 14b , 13c and 15c . magnetic pull forces act between the adjacent ones of the side magnetic teeth 11b1 , 11b2 of the stationary body 11 and the magnetic poles 13b , 15b of the movable body 12 , and between the adjacent one of the central magnetic teeth lla of the stationary body 11 and the magnetic pole 14c of the movable body 12 , as shown by the dotted lines in fig7 a . fig7 b shows the pole surfaces ( hatched ) of the magnetic poles on which the magnetic pull forces act . the movable body 12 steps forwards by 1 / 4p so as to take the position shown in fig7 a , from the position shown in fig6 a . next , at the same time when the other coil 21 is deenergized , a negative dc current - i is supplied to the one coil 20 for the predetermined time . induced magnetic fluxes by the coil 20 are added to the magnetic flux φ from the permanent magnet 18 in the magnetic poles 13d , 15d and 14a , while they are cancelled with it in the magnetic poles 14d , 13a and 15a . magnetic pull forces act between the adjacent ones of the side magnetic teeth 11b1 , 11b2 of the stationary body 11 and the magnetic poles 13d , 15d of the movable body 12 , and between the adjacent one of the central magnetic teeth 11a of the stationary body 11 and the magnetic pole 14a of the movable body 12 , as shown by the dotted lines in fig8 a . fig8 b shows the pole surfaces ( hatched ) of the magnetic poles on which the magnetic pull forces act . the movable body 12 steps forwards by 1 / 4p so as to take the position shown in fig8 a , from the position shown in fig7 a . next , at the same time when the one coil 20 is deenerigized , the negative dc current - i supplied to the other coil 21 for the predetermined time . induced magnetic fluxes by the coil 21 are added to the magnetic flux φ from the permanent magnet 18 in the magnetic poles 13c , 15c and 14b , while they are cancelled with it in the magnetic poles 14c , 13b and 15b . magnetic pull forces act between the adjacent ones of the side magnetic teeth 11b1 , 11b2 of the stationary body 11 and the magnetic poles 13c , 15c of the movable body 12 , and between the adjacent one of the central magnetic teeth 11a of the stationary body 11 and the magnetic pole 14b of the movable body 12 , as shown by the dotted lines in fig1 . fig9 b shows the pole surfaces ( hatched ) of the magnetic poles on which the magnetic pull forces act . the movable body 12 steps forwards by 1 / 4p so as to take the position shown in fig9 a , from the position shown in fig8 a . the above operation ( fig6 a to fig9 a ) are repeated , and the movable body 12 moves forwards 1 / 4p by 1 / 4p . actually , it looks continuously to move forwards . as above described , the magnetic poles ( 13a , 15a ) and 14d on which the magnetic pull forces act in the mode of fig6 a , are substantially at the same distance from the center of the movable body 12 in the moving direction a . similiary , the magnetic poles ( 13b , 15b ) and 14c ( in the mode of fig7 a ), ( 13d , 15d ) and 14a ( in the mode of fig8 a ) and ( 13c , 15c ) and 14b ( in the mode of fig9 a ) are substantially at the same distance from the center of the movable body 12 in the moving direction a . substantially the same magnetic pull forces act at both sides of the center of the movable body 12 on every pitch motion . accordingly , the magnetic pull forces always balance at both the center . although not shown , front and rear bearings provided on the right and left and portions of the movable body 12 do not vibrate , and so the noise level can be reduced . further , in the above embodiment , substantially the same magnetic pull forces act at body sides of the center line c 1 - c 1 along the moving direction a of the movable body 12 on every pitch motion ( refer to fig6 b to fig9 b ). further , in the above embodiment , the magnetic force center ( stable point ) can be determined by a pair of the substantially same magnetic forces at both sides of the center . accordingly , even when the iron cores 13 , 14 and 15 thermally expand , the characteristics of the linear pulse motor do not change . an accurate stop or positioning can be always obtained . fig1 shows a second embodiment of this invention . parts in fig1 which correspond to those in fig5 of the first embodiment , are denoted by the same reference numerals . first , the demerit of the first embodiment will be described with reference to fig1 , for facilitating the understanding of the second embodiment . in fig1 , the spacers 16 and 17 are made of non - magnetic material . however , leak magnetic flux φl always occurs . accordingly , amount of main magnetic flux φ to flow in the stationary body 11 is decreased . the efficiency of the linear pulse motor is lowered . extra energy should be consumed to compensate the leak magnetic flux φl for a predetermined drive force . further , pull force is decreased , and spring constant of the bearing is lowered . the noise level is high . the above drawback of the first embodiment can be removed by the second embodiment shown in fig1 . auxiliary permanent magnets 60 and 70 are used instead of the spacers 16 and 17 of the first embodiment . polarities of the magnets 60 and 70 are so determined as shown in fig1 , in relation to the polarities of the main permanent magnet 18 . thus , little leak magnetic flux occurs . almost all of magnetic flux φ &# 39 ; flow in the stationary body 11 . with the arrangements of fig1 , the efficiency of the linear pulse motor can be improved . the linear pulse motor can . be small - sized for the constant drive force . the magnetic pull force between the movable body and the stationary body can be increased . accordingly , the spring constant of the bearing can be increased , and so the noise level can be decreased . the other operations , effects and merits of the second embodiment are the same as those of the first embodiment . while the preferred embodiments have been described , variations thereto will occur to those skilled in the art within the scope of the present inventive concepts which are delineated by the following claims . for example , in the above embodiment , plural teeth may be formed in the lower surfaces of the magnetic poles 13a to 15a , 13bto 15b , 13c to 15c and 13d to 15d , respectively . in that case , plural teeth are formed correspondingly in the upper surfaces of the magnetic teeth 11a , 11b1 and 11b2 , respectively . further , in the above embodiment , the movable body 12 includes three iron cores 13 , 14 and 15 . however , it may include two or more than three iron cores . fig1 shows one modification of a linear pulse motor including two iron cores . in fig1 , a movable body 80 consists of a backplate 81 , a permanent magnet 82 , two iron cores 83 and 84 and coils 86 and 87 . the permanent magnet 82 consists of magnet regions 82a and 82b oppositely magnetized to each other , and non - magnet region 82c interposed between the regions 82a and 82b . the one magnet region 82a is superimposed on the one iron core 83 , while the other magnet region 82b is superimposed on the other iron core 84 . the iron cores 83 and 84 are magnetically separated from each other by a spacer 85 made of non - magnetic material . the iron cores 83 and 84 include four magnetic poles 83a to 83d and 84a to 84d , respectively , in the same manner as in the above embodiments . two rows of magnetic teeth 88a and 88b are formed in a stationary body 88 made of magnetic material . the magnetic teeth 88a and 88b are shifted in phase by a half of pitch ( 1 / 2p ) from each other . the one coil 86 is wound on the magnetic poles 83a , 84a and 83d , 84d in the same manner as the one coil 20 of the above embodiment . the other coil 87 is wound on the magnetic poles 83b , 84b and 83c , 84c in the same manner as the other coil 21 of the above embodiment . the coils 86 and 87 are energized and changed over in the same manner as the coils 20 and 21 of the above embodiment . the magnetic pull forces are generated at both sides of the center of the movable body 80 in the moving direction . fig1 a to fig1 d show the magnetic poles on which the magnetic pull forces act , every 1 / 4 pitch . it will be understood that the same effect as the above embodiment can be obtained by the modification . in the above embodiment , the central row of the magnetic teeth 11a is shifted from the side rows of the magnetic teeth 11b1 , 11b2 by 1 / 2p in phase . the magnetic poles of the central iron core 14 may also be shifted from those of the side iron cores 13 , 15 by 1 / 2p in phase , in the movable mody . in that case , the three rows of the magnetic teeth are aligned with each other in phase . in the above embodiment , the linear pulse motor is of two phase motor type . instead , it may be of three phase motor type . in that case , the movable body moves by 1 / 6 pitch .