US3749827A

US3749827A - Endless non-metallic belt for intermittently moving a transducer head transversely across a rotary magnetic disc

Info

Publication number: US3749827A
Application number: US00085463A
Authority: US
Inventors: H Kinjo; F Akuwa
Original assignee: Victor Company of Japan Ltd
Current assignee: Victor Company of Japan Ltd
Priority date: 1969-11-01
Filing date: 1970-10-30
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31
Also published as: DE2053525C3; DE2053525A1; DE2053525B2

Abstract

An intermittent feeding device provides a translation and intermittent feed to a recording and reproducing head used for cooperating with a rotary recording medium. An intermittent rotation driving source, such as a stepping motor, drives a belt intermittently thereby causing the transducer head secured on the belt to make intermittent stepping movements. Vibrations, such as a hunting of the rotary driving source, are absorbed by the belt and not transmitted to the tip of the transducer head.

Description

United States Patent Kinjo et al.

1451 July 31,1973

ENDLESS NON-METALLIC BELT FOR INTERMITTENTLY MOVING A TRANSDUCER HEAD TRANSVERSELY ACROSS A ROTARY MAGNETIC DISC Inventors: Hisao Kinjo; Fumio Akuwa, both of Yokohama, Japan Assignee: Victor Company of Japan, Ltd.,

Yokohama-City, Japan Filed: Oct. 30, 1970 Appl. No.: 85,463

Foreign Application Priority Data Nov. 1, 1969 Japan 44/87270 Aug. 17, 1970 Japan 45/71874 U.S. Cl. 178/6.6 DD, 179/1002 CA Int. Cl. H04m 5/78, G1 1b 21/08 Field of Search 179/1002 T, 100.2 CA,

179/1002 MD; l78/6.6 DD; 340/l74.1 C

[56] References Cited UNITED STATES PATENTS 3,176,083 3/1965 Hauser 179/1002 T 3,548,095 12 1970 Poulett l78/6.6 DD 3,291,920 12 1966 Hauser 179 1002 T Primary ExaminerBernard Konick Assistant Examiner-Robert S. Tupper AttorneyLouis Bernat [57] ABSTRACT 15 Claims, 13 Drawing Figures 1 1 O O J51, J21, 4i 1 3g i: 3': 45-: E 5 42 5/ L".

PAIENIE JUL 1 ma SHEEI 1 0F 5 P FIG. IA m FIG. 2

INVENTORS H/SHO KINJO BY FuM/o HKUWH O iu "can;

PAIENIwJum #915 3.749.827

sum 2 0r 5 III/4- INVENTORS HISHO KINJO BY Fum/o HKUWF) PATENTED 3 1 73 SHEET 3 OF 5 FIG. 5

INVENTORS HISFIO KINJO BY FUPHO HKUWF) PAIENIED JUL 3 I ma SHEET l 0F 5 FIG. 7

IIW

INVENTORS HISHO K/NJO BY O HKUWH PAIENIEDJUUWB 3.749.827

SHEEY 5 BF 5 INVENTORS H1390 KINJO ENDLESS NON-METALLIC BELT FOR INTERMITTENTLY MOVING A TRANSDUCER HEAD TRANSVERSELY ACROSS A ROTARY MAGNETIC DISC This invention relates to an intennittent feeding device for transducer heads, and more particularly to a device for providing a translational and intermittent feed to recording and reproducing heads for cooperating with a rotarty recording medium.

A magnetic recording and reproducing apparatus uses a rotary magnetic medium such as a rotary magnetic sheet or a rotary magnetic disk. A magnetic head, for recording on and reproducing from the rotary magnetic medium, generally needs to be moved by a translational feeding motion. In case a recording and a re producing are effected by forming concentric tracks on the rotary magnetic mdeium, the magnetic head is fed translationally and intermittently. Whereas, in case a recording and a reproducing are effected by forming a spiral track on the rotary magnetic medium, the magnetic head is fed translationally and continuously.

For providing a intermittent feed to the magnetic head, a device is employed which converts an intermittent rotary movement of the intermittent rotary driving source (such as a pulse motor or a stepping motor) into an intermittent linear and translational movement. A conventional magnetic head feeding device has used a mechanism comprising a feed screw provided on a rotary shaft of a pulse motor. A half nut is threaded on the feed screw. The half nut carries a magnetic head. Another conventional magnetic head feeding device has employed a mechanism having a pinion provided on a rotary shaft of a pulse motor and a rack which meshes with the pinion. The rack carries a magnetic head.

In a pulse motor, however,'hunting generally takes place when its intermittent rotary movement is started. In the aforementioned conventional devices, mechanical vibrations are caused during the intermittent rotary movement of the pulse motor. These vibrations are directly transmitted to the tip of the magnetic head. In this case, the magnetic head cannot maintain its normal contact with the rotary magnetic medium and jitters will take place. Further, the magnetic head makes contact with the rotary magnetic medium at a position which is out of a normal contact position, whereby mistrackings of the magnetic head on the magnetic medium may occur.

A further conventional magnetic head feeding device has employed a steel belt fixedly carrying a magnetic head on the upper surface thereof. The steel belt is wound at both ends around two driving pulleys. In this conventional device, the magnetic head carried on the steel belt is moved by winding the steel belt on one of the rotating driving pulleys. This device has an advantage in that there is no slippage of the belt. On the other hand, however, this device is disadvantageous in that the diameter of the wound steel belt on the driving pulley gradually changes as the steel belt is wound around the driving pulley. Thus, the magnetic head is prevented from effecting an intermittent movement at an equal interval, and the pitch of the track formed on the rotary magnetic medium gradually changes and cannot be maintained at a constant value.

It is, therefore, a general object of the present invention to provide a novel and useful intermittent feeding device for transducer heads which can eliminate the afore-mentioned disadvantages of the conventional devices.

Another object of the invention is to provide an intermittent feeding device for transducer heads in which mechanical vibrations produced by a rotary driving source are not transmitted directly to the transducer heads. Accordingly, an occurrence of jitter in'recording and reproducing signals can be prevented.

A further object of the invention is to provide a device which is capable of feeding intermittently a transducer head for forming tracks of equal pitches on a rotary recording medium. Accordingly, a very accurate tracking of the transducer head on the recording medium is obtainable in the device according to the invention.

A further object of the invention is to provide a device which is capable of eliminating a sliding slippage due to overload and an elastic slippage due to the elasticity of a belt, thereby feeding a transducer head by the belt without slipping.

A still further object of the invention is to provide a transducer head feeding device in which an intermittent rotary stepping angle of an intermittent rotary driving source in made greater and the diameter of a driving shaft is made larger by the employment of a reduction gear. By this arrangement, torque load can be reduced according to a reduction of gear ratio and also a stepping pitch angle error can be reduced.

These and other objects and features of the invention will become apparent from the following description made with reference to the accompanying drawings, in which:

FIGS. 1A to 1C are graphical diagrams respectively showing driving pulse wave forms, a stepping response characteristic of a pulse motor and its oscillation phenomenon;

FIG. 2 is a side elevation of an embodiment of a recording and reproducing apparatus using a rotary magnetic disk to which a device according to this invention is applied;

FIG. 3 is a schematic plan view of a first embodiment of the device according to the invention;

FIG. 4 is a side elevation view of the device shown in FIG. 3;

FIG. 5 is a plan view of a second embodiment of the device according to the invention;

FIG. 6 is a side elevation of the device shown in FIG.

FIG. 7 is a schematic plan view of a third embodiment of the device according to the invention;

FIG. 8 is a side elevation view of the device shown in FIG. 7;

FIG. 9 shows a pattern of tracks formed on the rotary magnetic disk;

FIG. 10 is a schematic plan view of a fourth embodiment of the device according to the inventiomand FIG. 11 is a side elevation view of the device shown in FIG. 10.

Referring now to FIG. 1, a group of driving pulses P having a period of, for example, one-thirtieth seconds as shown in FIG. 1A is applied to a pulse motor. The pulse motor generally makes an intermittent rotary movement with a stepping response characteristic as shown in FIG. 1B. The rotation of the motor builds up within a period of time t, after its rotation is started. At the end of building-up of the motor rotation there is, an

overshooting, and a subsequent hunting phenomena occurs. it takes a period of time t before the hunting substantially ends. If this rotational oscillations or vibrations are transmitted directly to a magnetic head, vibrations as shown in FIG. 1C occur at a tip of the magnetic head. The recording or reproducing by the magnetic head must occur within the period of onesixtieth seconds (t before the motor starts its next intermittent rotary movement. At the initial portion of this period t the aforementioned hunting has not yet completely ceased.

In the conventional devices as hereinabove described, the magnetic head is obliged to start its recording or reproducing before the hunting has completely ceased. In this case, the magnetic head cannot contact the rotary magnetic medium under a normal condition. Therefore, mechanical jitters are produced in recording or reproducing signals. At the same time, mistrackings of the magnetic head will occur on the rotary magnetic medium.

In the device according to the invention hereinbelow described, the aforementioned disadvantages of the conventional devices are completely eliminated.

One embodiment of the recording and reproducing apparatus using a rotary magnetic disk to which the device according to the invention is applied will now be illustrated with reference to FIG. 2. A magnetic disk having upper and lower magnetic surfaces is rotated by a disk motor 11 at a rotation velocity of 60 r.p.s.

Pulse motors

12a and 12b supported on the mounting table are rotated alternately and intermittently by driving pulses which are applied to the motors. Belts 13a and 13b are intermittently driven by the

pulse motors

12a and 12b. Magnetic heads 14a and 14b are secured to the belts 13a and 13b so as to contact the magnetic disk 10.

The magnetic heads 14a and 14b are intermittently and alternately stepped forward by intermittent rotation of the

pulse motors

12a and 12b. The magnetic heads 14a and 14b are translationally stepped in a radial direction across the magnetic disk 10. The magnetic heads 14a and 14b record and reproduce video signals, of one field unit per concentric track, on the magnetic disk 10. Recording or reproduction occurs while magnetic heads are in a standstill state.

Each embodiment of the transducer head feeding device including the pulse motor and belt will now be described.

FIGS. 3 and 4 show the first embodiment of the device according to the invention. A driving shaft 21 is directly driven by a stepping motor 20, with an intermittent stepping rotation. A flat or plane belt 22 is provided between the driving shaft 21 and a driven shaft 23, the belt forming an endless loop. The belt 22 is made of a material of relatively small strain. The outer peripheral surfaces of the driving shaft 21 and the driven shaft 23 are knurled so as to prevent slipping of the belt 22.

A pinch roller 24 is rotatably supported between ends of arms 25. The arms 25 are pivotally mounted on brackets 26 which rotatably support the driving shaft 21. Springs 27, provided between the arms 25 and the brackets 26, cause the pinch roller 24 to press against the belt 22 wound around the driving shaft 21. The driven shaft 23 is rotatably supported between ends of arms 28 which are pivotally mounted on brackets 29. Springs 30, for providing an initial tension and a back tension to the belt 22, are provided between the arms 28 and a fixed part of the apparatus. In FIG. 3, the arms 28 receive rotating forces in the counterclockwise direction from the springs 30, so that the belt 22 receives a greater tension.

A head supporting base 31 is secured to the belt 22. A video signal recording and reproducing magnetic head 32 is mounted on the base 31. A linear guide bar 33 is provided in parallel with the moving direction of the belt 22. A guide 34 formed integrally with the base 31 engages the guide bar 33. As the belt 22 moves, the head 32 is guided by the guide bar 33 and the guide 34.

The driving shaft 21 is rotated intermittently by the intermittent rotation of the stepping motor 20, whereby the belt 22 moves translationally and intermittently. This causes the magnetic head 32 to make a translational and intermittent stepping movement. The accuracy of the position of tracks formed by the magnetic head 32 on the roatry magnetic disk depends upon the accuracy of one step of the belt 22. The accuracy of the guide bar 33 and the guide 34 determines the accuracy of the position of the magnetic head 32, in the rotational tangential direction of the magnetic disk, as related with the occurrence of jitter.

In a power transmission system using a flat belt, there are generally two kinds of slippage, namely, a sliding slip and an elastic slip. In the power transmission systern of the present embodiment, a great initial tension is applied to the belt to prevent the sliding slip due to an overload. Furthermore, the pinch roller 24 is cuased to press against the belt 22 thereby to hold the belt 22 between the driving shaft 21 and the pinch roller 24. The sliding slip generally does not take place unless the belt is overloaded. The aforementioned construction of the embodiment is sufficient to prevent occurrence of such sliding slips.

In order to prevent the elastic slip, the belt 22 is made of a material which is flexible, but not elastic, and it has a suitable viscosity resistance and a small strain. In the present embodiment, the belt 22 consists of a glass fiber belt body coated with polyurethane resin. A strain caused by a difference between a tension force on the tight side of the belt and a tension force on the slack side of the belt is small. The difference between an elongation of the tight side of the belt and an elongation of the slack side of the belt is substantially zero. Accordingly, occurrence of the elastic slip can be avoided.

Furthermore, the driven shaft 23 is energized by the springs 30 to apply a constant back tension to the belt 22 in the same direction as the direction of the initial tension. In other words, the driven shaft 23 performs a function of a tension roller. Accordingly, a slippage due to the elongation of the belt, with lapse of time, can be avoided. Thus, in the device of the aforementioned construction, the sliding slippage due to overload and the elastic slippage due to elasticity of the belt are eliminated. Moreover, the vibrations caused by the starting of the intermittent rotation of the stepping motor 20 are effectively damped by the belt 22 and are not transmitted to the tip of the magnetic head 32.

The second embodiment of the device according to the invention will now be described with reference to FIGS. 5 and 6. A stepping motor 40 drives a driving shaft 42 through a coupling 41 and causes intermittent rotations of the driving shaft 42. The driving shaft 42 is rotatably mounted on a bracket 43 secured to a base 44. A driven shaft 45 is rotatably mounted on a bracket 46 which is mounted on the base 44 so as to pivot slightly about an axis 47. In this embodiment, a rotational angle for one step of the stepping motor 40 is 1.8", and the diameters of the driving shaft 42 and the driven shaft 45 are 8.0 mm, respectively. A flat or plane belt 48 is provided between the driving shaft 42 and the driven shaft 45. In this embodiment, the belt 48 consists of silicon rubber containing glass fiber cloth. The outer peripheral surfaces of the driving shaft 42 and the driven shaft 45 are knurled so as to prevent a slipping of the belt 48.

The bracket 46 is provided with screws 50 threaded therewith. The screws 50 have head portions 51. The ends of the screws 50 always contact a side of a fixed bracket 49. Accordingly, the bracket 46 can be pivoted slightly by turning the head portions 51 of the screws 50, whereby the distance between the bracket 46 and the bracket 49 can be adjusted. Thus, the distance be tween the driving shaft 42 and the driven shaft 45 can be adjusted. By this arrangement, the initial tension applied to the belt 48 is adjustable so that the difference between an elongation the tight side of the belt and an elongation of the slack side of the belt may become substantially zero.

Two

guide bars

52a and 52b are supported between the

brackets

49 and 53 in parallel with the belt 48. A head supporting base 54, having

guides

55a and 55b at opposite ends thereof, is secured to the belt 48. The

guides

55a and 55b are respectively engaged with the guide bars 52a and 52b. A head assembly 57, including head tips 56, is mounted on the base 54. A screw 58 for adjusting the head tip position is also provided on the base 54. The weights of the base 54 and the head assembly 57 should preferably be as small as practicably possible. 7

A switch operating cam 59 protrudes from a side of the guide 55a. A safety limit switch 60 is mounted on the bracket 49. When the head assembly 57 has completed its intermittent movement to the left end in the figure, the cam 59 pushes an actuator 61 of the switch 60 thereby opening the switch 60. The switch 60 opens the power circuit of the stepping motor 40 so as to stop the "rotation of the motor. A safety limit switch 62 is mounted on the base 44. When the magnetic head assembly 57 has completed its intermittent movement to the right end in the figure, the cam 59 pushes anactuator 63 of the switch 62 thereby stopping the rotation of the stepping motor 40. A magnet switch 64 is adapted for stopping the magnetic head assembly 57 when it is brought back to a starting position. When the magnetic head assembly 57 moves leftward, as viewed in the figure, by a quick return motion and has reached a predetermined recording and reproducing starting postion, a magnet 65 contained in the cam 59 energizes the switch 64, which opens to stop the motor 40.

As in the case of the first embodiment hereinabove described, the belt 48 effects its translational and intermittent movement by the intermittent rotation of the stepping motor 40, thereby causing the head tips 56 of the magnetic head assembly 57 to make a stepping movement in a radial direction over the magnetic disk. It is to be noted that, in this embodiment, there are no members corresponding to the pinch roller 24 and the springs 30 used in the aforementioned first embodiment. The same accuracy can be achieved, in this embodiment, by turning the screws 50 and setting the initial tension of the belt 48 at a predetermined value.

The third embodiment of the device according to the invention will now be illustrated with reference to FIGS. 7 and 8. Throughout FIGS. 5 to 8, the same or similar components are designated by the same reference numerals and the description thereof will be omitted hereafter. A pulse motor is provided with a small gear 71 on the rotary shaft thereof. The driving shaft 42 is provided with a large gear 72 at one end thereof. The gear 71 meshes with the gear 72. The number of teeth of the gear 71 is n while the number of the gear 72 is N n). The intermittent rotation of the pulse motor 70 is transmitted by way of the reduction gear mechanism consisting of the

gears

71 and 72 to the driving shaft 42 thereby moving the belt 48 translationally and intermittently.

In a pulse motor, generally, if an angle of one step corresponding to an application of one pulse, is to be made smaller than a certain degree, the number of poles of the motor and the corresponding number of teeth of the gear must be increased. In this respect, the construction of the motor is complicated, and a sufficient accuracy of the stepping angle can be obtained. Accordingly, the stepping angle of pulse motors which are generally and practicably used is approximately 2 or more.

On the other hand, in case video signals are recorded and reproduced on a rotary magnetic disk, the feed pitch of a magnetic head is made as small as possible,

and the number of tracks is made as large as possible so that a recording and reproducing capacity of the disk may be increased. For example, it is required that the width of feed pitch of the head he on the order of to 200 p..

In FIG. 9, a part of the track pattern formed on the magnetic disk 10 is shown. Tracks having a width of T' are concentrically formed with guard bands G interpsed therebetween. It is now assumed that the distance between centers of adjacent tracks (i.e., track pitch P,) is, for example, 100 and the diameter of the driving shaft 42 is r mm. If the driving shaft 42 is directly connected to the rotary shaft of the pulse motor 70, without employing the reduction gears 71 and 72, the following formula is obtained.

M360 me where r is the diameter of the driving

shaft

42 and 0 is the angle of one step of the pulse motor 40.

From the above formula, r= 360P,/1r 6 If 0 is 2, r (360 X0.l)/(3.l4 X2") 5.7 (mm) In the above calculation, thickness of the belt is neglected.

In a practical device, however, it the diameter of the driving shaft 42 is reduced to 5.7 mm, the radius of cur accuracy and arrangement of a rotor and a stator, elec-' trical irregularity in a driving circuit, and other factors. This pitch angle error does not become greater even if the stepping angle of the pulse motor is made larger by applying a plurality of pulses to the motor instead of a single pulse.

Accordingly, the ratio of the pitch angle error, relative to displacement of the head effected by stepping, becomes small by using a plurality of pulses instead of a single pulse to move the head by one pitch, whereby the accuracy of the tracking is improved. Here, the pitch angle error is designated by A0, and an angle of one intermittent rotary movement of the pulse motor is designated by 0. If one intermittent rotary movement of the pulse motor causes the magnetic head to make one step, the intermittent rotational angle is +A6. If two intermittent rotary movements of the pulse motor causes the magnetic head to make one step, the intermittent rotational angle is ZHAO. Accordingly, a greater number of intermittent rotary movements of the pulse motor for one stepping movement of the magnetic head increases the relative accuracy of the stepping position of the magnetic head. It is, therefore, more advantageous to use two or three pulses as one unit for driving the pulse motor than to drive it by a single pulse.

This, however, is inconsistent with the aforementioned requirement for making the diameter of the driving shaft 42 as large as possible. For example, if two pulses are used in one unit to feed the head by one pitch the diameter of the driving shaft 42 needs to be slightly less than 3 mm. A driving shaft of such a small diameter can not be practically used.

In the device according to the present embodiment, the reduction gear mechanism consisting of the

gears

71 and 72 is used for changing the rotational angle and thereby obtaining a drivinG shaft 42 of a preferred diameter. In this embodiment, the gear ratio of the gear 71 having the teeth number n and the gear 72 having the teeth number N is now selected as N n 4: l. The pulse motor is normally driven by 4 pulses to cause the magnetic head to make 2 steps and it is driven by 2 pulses to cause the magnetic head to make 1 step when the stepping movement of the magnetic head is reversd. ln this case,

From the above formula, 11' r/360 r x 11.5 mm

Therefore, according to this embodiment, a driving shaft of a large diameter can be used and, at the same time, the stepping pitch angle error of the pulse motor can be made less than one-half. Furthermore, by virture of employing the reduction gear mechanism, the load to the pulse motor shaft is reduced at the same ratio as the reduction gear ratio. Hence, a load torque on the pulse motor shaft is comparitively small, i.e. about one quarter of the conventional device.

The fourth embodiment of the device according to the invention will be described with reference to FIGS. l0 and 11. Throughout FIGS. to 11, the same or similar components are designated by the same reference numerals and the description thereofis omitted. A driving shaft 80 having the gear 72, attached thereto is provided with gear portions 810 and 81b spaced apart from each other at a predetermined distance. A driven shaft 82 is also provided with

gear portions

83a and 83b spaced apart from each other at a predetermined distance. Endless timing belts 84a and 84b are respectively provided between the

gear portions

81a and 83a and between the gear portions 81b and 83b. The head supporting base 54 is secured to the timing belts 84a and 84b.

The timing belts 84a and 84b are respectively formed with involute teeth on their inner sides. The

gear portions

81a, 81b, 83a and 83b have also involute teeth which mesh with the teeth of the timing belts 84a and 84b. Accordingly, backlash between the timing belt 84a and the

gear portions

81a and 83a and between the timing belt 84b and the gear portions 81b and 83b are very small. An accurate driving can be effected.

According to this embodiment, the application of initial tension to the belt is not required since the belt is meshed with the driving shaft. Hence an unnecessary load is not applied to the pulse motor 70, whereby a more accurate intermittent stepping movement of the magnetic head is ensured.

In the first and second embodiments as previously described, the timing belt may be used instead of the flat belt. Gear portions which mesh with the timing belts may be provided on the driving shaft and the driven shaft respectively.

What we claim is:

1. An intermittent feeding device for a transducer head comprising a transducer head for recording and reproducing on a rotary magnetic medium, an intermittent rotary driving source means for intermittently moving said transducer head, a driving shaft connected to said rotary driving source means, said driving shaft being knurled on its outer peripheral surface and intermittently rotated by said intermittent rotary driving source means, a rotatable driven shaft knurled on its outer peripheral surface, an endless, flexible, nonmetallic flat belt means trained around and extending between said driving shaft and said driven shaft, said transducer head being secured to said belt, and guide means for guiding said head in a path transverse to the direction of movement of said rotary magnetic medium.

2. The device of claim 1 and means for tensioning said belt between the driving shaft and the driven shaft with a large initial tension so that there is substantially no difference in elongation between the tight side and the slack side of the belt.

3. The device of claim 1 which further comprises means for adjusting the distance between the driven shaft and the driving shaft so as to adjust the tension applied to the belt.

4. The device of claim 1 which further comprises a pinch roller, said belt being wound around the driving shaft and passing between said shaft and pinch roller, and means for energizing the driven shaft in a direction which tightens the belt so as to provide an initial tension and a back tension to the belt.

5. The device of claim 1 wherein said rotary driving source means is an intermittently rotary motor, said rotary magnetic medium is a rotary magnetic disk, said belt is a fiber member, and means comprising said belt for causing said transducer head to make an intermittent stepping movement radially across the rotary magnetic disk responsive to an intermittent movement of the belt accompanying an intermittent rotation of the motor.

6. The device of claim 5 which further comprises a first gear mounted on the rotary shaft of the rotary motor and a second gear mounted on the driving shaft, said first gear meshing with the second gear, said second gear having a larger number of teeth than the number of teeth of the first gear, and said first and second gears forming a rotary reduction gear mechanism.

7. An intermittent feeding device for transducer heads comprising two transducer heads for recording and reproducing video signals on a rotary magnetic medium, a pair of driving means each for intermittently and alternately moving one of said two magnetic heads respectively to form a path, to record every other field of the video signals, each of said driving means including a driving shaft, operator means responsive to driving pulses for intermittently rotating said driving shaft over a step of a predetermined angle, a rotatable driven shaft, belt means extending between said driving shaft and said driven shaft and having one of the transducer heads secured thereto, said belt being made of a flexible, non-elastic material, guide means for guiding the one of the transducer heads in a path transverse to the direction of movement of said rotary magnetic medium, said belt being a flat belt, said driving shaft and said driven shaft being respectively knurled on their outer peripheral surfaces, and means for tensioning said belt wherein said belt comprises a glass fiber belt body coated with polyurethane resin.

8. An intermittent feeding device for transducer heads comprising two tranducer heads for recording and reproducing video signals on a rotary mangetic medium, a pair of driving means each for intermittently and alternately moving one of said two magnetic heads respectively to form a path, to record every other field of the video signals, each of said driving means including a driving shaft, operator means responsive to driving pulses for intermittently rotating said driving shaft over a step of a predetermined angle, a rotatable driven shaft, belt means extending between said driving shaft and said driven shaft and having one of the transducer heads secured thereto, said belt being made of a flexible, non-elastic material, guide means for guiding the one of the transducer heads in a path transverse to the direction of movement of said rotary magnetic medium, said belt. being a flat belt, said driving shaft and said driven shaft being respectively knurled on their outer peripheral surfaces, and means for tensioning the belt, wherein said belt comprises a combination of silicon rubber and glass fiber cloth.

9. An intermittent feeding device for transducer heads comprising two transducer heads for recording and reproducing video signals on a rotary magnetic medium, a pair of driving means each for intermittently and alternately moving one of said two magnetic heads respectively to form a path, to record every other field of the video signals, each of said driving means including a driving shaft, operator means responsive to driving pulses for intermittently rotating said driving shaft over a step of a predetermined angle, a rotatable driven shaft, belt means extending between said driving shaft and said driven shaft and having one of the transducer heads secured thereto, said belt being made of a flexible, non-elastic material, guide means for guiding the one of the transducer heads in a path transverse to the direction of movement of said rotary magnetic medium, said belt being a flat belt, said driving shaft and said driven shaft being respectively knurled on their outer peripheral surfaces, and means for tensioning said belt, wherein said tensioning means comprises means for adjusting the distance between the driving shaft and the driven shaft in order to adjust the tension in the belt.

10. An intermittent feeding device for transducer heads comprising two transducer heads for recording and reproducing video signals on a rotary magnetic medium, a pair of driving means each for intermittently and alternately moving one of said two magnetic heads respectively to form a path, to record every other field of the video signals, each of said driving means including a driving shaft, operator means responsive to driving pulses for intermittently rotating said driving shaft over a step of a predetermined angle, a rotatable driven shaft, belt means extending between said driving shaft and said driven shaft and having one of the transducer heads secured thereto, said belt being made of a flexible, non-elastic material, guide means for guiding the one of the transducer heads in a path transverse to the direction of movement of said rotary magnetic medium, and means for tensioning the belt, wherein said belt is a flat belt, said tensioning means comprises spring means for energizing the driven shaft in a direction which tightens the belt, and said driving shaft and said driven shaft having knurled outer peripheral surfaces, the device further comprising a pinch roller for pressing the belt against the driving shaft.

11. An intermittent feeding device for transducer heads comprising two transducer heads for recording and reproducing video signals on a rotary magnetic medium, a pair of driving means each for intermittently and altemately moving one of said two magnetic heads respectively to record every other field of the video signals, each of said driving means including a driving shaft, operator means responsive to driving pulses for intermittently rotating said driving shaft over a step of a predetermined angle, a rotatable driven shaft, belt means extending between said driving shaft and said driven shaft and having one of the transducer heads secured thereto, said belt being made of a flexible, nonelastic material, guide means for guiding the one of the transducer heads in a path transverse to the direction of movement of said rotary magnetic medium, and means for tensioning the belt, wherein said belt is a tim- 'ing belt formed with involute teeth on the inner side,

both said driving shaft and said driven shaft having involute teeth in meshing engagement with the involute teeth of the timing belt.

12. The device of claim 11 wherein said operator means has a rotary shaft, a first gear mounted on the rotary shaft, and a second gear mounted on the driving shaft, said first gear meshing with the second gear, the number of teeth on said second gear being greater than the number of teeth on the first gear, and said first and second gears forming a rotary reduction gear mechanrsm.

13. An intermittent feeding device for a transducer head comprising a transducer head for recording and reproducing signals on a rotary magnetic medium, a driving shaft, a rotatable driven shaft, an endless, flexible, non-metallic belt trained around and extending between only the driving shaft and the driven shaft, said belt having a large initial tension so that therev is substantially no difference in tension between the tight side and the slack side of the belt, said belt having said transducer head secured thereto, rotary driving source means for intermittently rotating the driving shaft, and guide means for guiding the head in a path transverse to the direction of movement of said rotary magnetic 15. The device of claim 13 which further comprises a first gear mounted on the rotary shaft of the rotary driving source means and a second gear mounted on the driving shaft, said first gear meshing with the second gear, said second gear having a larger number of teeth than the number of teeth of the first gear, and said first and second gears forming a rotary reduction gear mechanism.

Claims

1. An intermittent feeding device for a transducer head comprising a transducer head for recording and reproducing on a rotary magnetic medium, an intermittent rotary driving source means for intermittently moving said transducer head, a driving shaft connected to said rotary driving source means, said driving shaft being knurled on its outer peripheral surface and intermittently rotated by said intermittent rotary driving source means, a rotatable driven shaft knurled on its outer peripheral surface, an endless, flexible, non-metallic flat belt means trained around and extending between said driving shaft and said driven shaft, said transducer head being secured to said belt, and guide means for guiding said head in a path transverse to the direction of movement of said rotary magnetic medium.

8. An intermittent feeding device for transducer heads comprising two tranducer heads for recording and reproducing video signals on a rotary mangetic medium, a pair of driving means each for intermittently and alternately moving one of said two magnetic heads respectively to form a path, to record every other field of the video signals, each of said driving means including a driving shaft, operator means responsive to driving pulses for intermittently rotating said driving shaft over a step of a predetermined angle, a rotatable driven shaft, belt means extending between said driving shaft and said driven shaft and having one of the transducer heads secured thereto, said belt being made of a flexible, non-elastic material, guide means for guiding the one of the transducer heads in a path transverse to the direction of movement of said rotary magnetic medium, said belt being a flat belt, said driving shaft and said driven shaft being respectively knurled on their outer peripheral surfaces, and means for tensioning the belt, wherein said belt comprises a combination of silicon rubber and glass fiber cloth.

11. An intermittent feeding device for transducer heads comprising two transducer heads for recording and reproducing video signals on a rotary magnetic medium, a pair of driving means each for intermittently and alternately moving one of said two magnetic heads respectively to record every other field of the video signals, each of said driving means including a driving shaft, operator means responsive to driving pulses for intermittently rotating said driving shaft over a step of a predetermined angle, a rotatable driven shaft, belt means extending between said driving shaft and said driven shaft and having one of the transducer heads secured thereto, said belt being made of a flexible, non-elastic material, guide means for guiding the one of the transducer heads in a path transverse to the direction of movement of said rotary magnetic medium, and means for tensioning the belt, wherein said belt is a timing belt formed with involute teeth on the inner side, both said driving shaft and said driven shaft having involute teeth in meshing engagement with the involute teeth of the timing belt.

12. The device of claim 11 wherein said operator means has a rotary shaft, a first gear mounted on the rotary shaft, and a second gear mounted on the driving shaft, said first gear meshing with the second gear, the number of teeth on said second gear being greater than the number of teeth on the first gear, and said first and second gears forming a rotary reduction gear mechanism.

13. An intermittent feeding device for a transducer head comprising a transducer head for recording and reproducing signals on a rotary magnetic medium, a driving shaft, a rotatable driven shaft, an endless, flexible, non-metallic belt trained around and extending between only the driving shaft and the driven shaft, said belt having a large initial tension so that there is substantially no difference in tension between the tight side and the slack side of the belt, said belt having said transducer head secured thereto, rotary driving source means for intermittently rotating the driving shaft, and guide means for guiding the head in a path transverse to the direction of movement of said rotary magnetic medium wherein said belt is a flat belt, and said driving shaft and said driven shaft are respectively knurled on their outer peripheral surfaces.

14. The device of claim 13 which further comprises a pinch roller, said belt being wound Around the driving shaft and passing between said shaft and pinch roller, and means for energizing the driven shaft in a direction which tightens the belt so as to provide an initial tension and a back tension to the belt.

15. The device of claim 13 which further comprises a first gear mounted on the rotary shaft of the rotary driving source means and a second gear mounted on the driving shaft, said first gear meshing with the second gear, said second gear having a larger number of teeth than the number of teeth of the first gear, and said first and second gears forming a rotary reduction gear mechanism.