FR2658648A1 - VARIABLE TORQUE TYPE COIL DRIVE. - Google Patents

Abstract

Coil drive device of the variable torque type of a magnetic recording and reproducing device, having coil drive means (10, 20) for selectively actuating coils according to their direction of rotation, means ( 40) to produce a variable torque disposed on a shaft (51), a reel speed change means (30) for changing the speed of the reels. The means for producing variable torque has an inclined cam (42) and a friction element (22) fixed on a drive pulley (10; 20) and causes speed slip by means of a pulley washer (14) by relative to a means (43a) for transmitting compressed energy by displacement of the cam. The reel speed changing means has a clutch member (32) and a lever (54) which is operated only in a desired mode.

Description

Coil drive device of the variable torque type

corn.

  The present invention is generally

  with a idler roller drive mechanism to

  selectively dragging a take-up reel disc equipped with a tape take-up reel and a take-up reel disc equipped with a tape take-up reel in a

  tape recorder and, more particularly, to a provision

  variable torque type coil drive device which can be driven by a friction force in a low speed drive mode and which, depending on its direction of rotation, can be driven by a variable torque in a search mode reverse image (RPS) and is driven

  directly by a driving force in a training mode

high speed.

  Generally, the operating mode for driving a reel in a video recorder has the following three modes: first, a reproduction mode (PB) which drives a tape at normal speed; second, an accelerated forward image search mode that scrolls forward (clockwise) a tape at a speed faster than the tape playback speed to search for a desired image and an image search mode in reverse

  (RPS) which scrolls in reverse (in the direction of

  milking clockwise) the tape at a faster speed than the tape playing speed to find a desired image; third, fast forward (F / F) and rewind (REW) modes that move quickly forward and backward without reproduction

(representation) of images.

  Among these cases, in the image search mode

  in the opposite direction, the belt tension becomes high

  aunt and the tape guide function is impaired, so that variations in the tape tension such as high tension and relaxation occur irregularly, making it impossible to record and reproduce the tape This results in the formation of noise In order to stabilize this, a higher torque than the turning torque of the tape reel in the

reproduction mode is required.

  Consequently, for this purpose, the

  torque demand in the operating mode of the belt.

  As a torque control method, a

  gear train process or variable torque process.

  However, the use of the gear train process

  causes a complicated structure and a high manufacturing cost

  cation Therefore, the recent trend has been to utili-

  generally the variable torque process.

  With reference to Figure 1 which represents a system

  tape of a video tape as an example of a video tape recorder, a reel drive section will be explained In Figure 1, a T tape is

  delivered in the direct or reverse direction by a coil

  drive SR and a take-up reel TR and is also delivered at constant speed by a capstan shaft CS and a pinch roller If a drive mechanism D is driven by the rotational force of a capstan motor CM which rotates said capstan shaft CS, the coil discs RD and RD 'of said supply coil

  SR and the take-up reel TR are selectively in-

  dragged by a crazy id roller oscillating to the left or the

  right in the direction of rotation of said drive mechanism

  ment. In other words, when driving said idle idler roller clockwise, said take-up reel disc RD 'is driven in the direction

  clockwise and also during training

  counterclockwise of said idler roller, said supply coil disc RD is

  driven counterclockwise.

  And, since said take-up reel disc RD 'is provided at a short distance from said capstan motor CM, a large driving force (torque) is not necessary when the tape is scrolled clockwise. T However, since said coil disc

  debtor RD is planned at a relatively important distance -

  te of it, when searching for image in the opposite direction RPS of the T-band, a significant load is applied, thus requiring a higher drive torque than

  in said scroll clockwise

  tre of the T-band Also, in a scrolling mode at high speed, not in the case of normal scrolling (scrolling at low speed), since said capstan motor CM is driven in rotation at high speed, one of said two discs coil RD and RD 'is selectively driven At this time, however, no slip should be generated in the power transmission system (gear system) and the driving force is transferred

as is.

  Depending on the drive mode of the bo-

  bine, the couple must be modified and also, according to the

  drive speed, the training condition

  by the driving force or the condition of friction transmission of the driving force must be modified in an adequate manner. Such a variation is generally effected by the drive mechanism D of said roller.

crazy ID.

  An example of such a conventional drive mechanism

  sique as described above is disclosed in the application

  of Japanese Utility Model published NO 1-109835, which

  relies on the torque and has the functions of drive by the motive force and by the friction transmission of this motive force However, in this structure of conventional drive mechanism, a large quantity of elements is necessary and in particular for a torque variable, three friction elements and four springs

  are used Therefore, a significant loss of energy

  it is provoked and a high manufacturing cost is necessary

  saire In addition, its assembly is very complicated or inconvenient.

  One of the aims of the present invention is therefore

  sequent to propose a simple drive mechanism for-

  seen from a single friction element and two springs.

  Another object of the present invention is to provide

  reduce energy loss as low as possible, thus ensuring reliable training using variable torque

and driving force.

  In order to achieve the above object of the invention, there is provided a coil drive device of the variable torque type of a recording and recording device.

  magnetic reproduction comprising means for driving

  coil for selectively actuating coils according to their direction of rotation; means for producing a variable torque arranged on a shaft; a means of change

  reel speed to change the speed of the reels.

  In a preferred embodiment of the present invention disclosed herein, said means for producing a

  variable torque may include an inclined cam.

  In addition, said means for producing a variable torque causes the speed to slip with the aid of a pulley washer with respect to an energy transmission means.

  compressed by displacement of said inclined cam.

  In the preferred embodiment of the present invention, said reel speed changing means may include a clutch member and a

  lever that operates only in a desired mode.

  In addition, said means for producing a variable torque of the coil drive device according to the present invention may include a friction element

  fixed on a drive pulley.

  Thus, the present invention aims to provide a coil drive device in which the energy

  is transmitted by a motive force in a rotational mode

  tion at high speed and by a force transmitted by fric-

  tion delivering a predetermined torque in a mode of re-

  looking for reverse image and which transmits energy with variable torque according to its direction of rotation in a drive

by friction.

  With a coil drive device of the present invention, during an image search in reverse, since a guide is pushed by the movement of a cam guide projection along the inclined cam , a speed slip is produced between the drive pulley and the rotary assembly by the pulley washer, so that the torque is produced under the action of the force of a compressed spring and the speed slip on the pulley washer Thus the problems of the prior art, during the image search mode in the

  reverse, can be resolved.

  The foregoing objects, as well as others, as well as the advantages of the present invention will become apparent from the

  description which follows of the present invention opposite

  accompanying drawings in which: Figure 1 schematically shows a tape running system for explaining the reel drive section of a conventional VCR; Figure 2 is an exploded perspective view showing a coil drive device according to a preferred embodiment of the present invention; Fig. 3 is a sectional view showing the coil drive device in the assembled state according to the embodiment of the present invention;

  Figure 4 is a partial sectional view shown

  schematically sensing a portion of a second rotary assembly to explain the operation of a cam according to the present invention; and

  Figure 5 is an explanatory view in order to explain

  quer operation of a clutch in high speed scrolling modes (fast forward and rewind) of the coil drive device according to the present invention. The invention will now be described in detail in

reference to the drawings.

  In Figure 2, which is an exploded perspective view showing a coil driving device

  according to a preferred embodiment of the present invention

  tion, a drive pulley 10, a rotary assembly

  of friction force transmission, a first set of

  ble rotary 30 and a second rotary assembly 40 together constitute a single assembly and are supported on a

  support shaft 51 mounted on a plate 50.

  Said drive pulley 10 is in the form of a belt pulley and includes a belt groove

  11 formed to place a belt 52 on its outer surface

  upper, a boss introduction hole 12 made in its central part and a plurality of rod introduction holes 13 made, uniformly distributed, at the periphery

  of said boss introduction hole 12.

  In the coil drive of the

  present invention, said drive pulley can use

  read a capstan motor to deliver a tape,

as a source-drive.

  Said rotary assembly 20 for friction force transmission is provided with a two-step boss 21 which comprises a large diameter part 21 a and a small diameter part 21 b Said large diameter part 21 a is introduced into said hole d introduction 12 of boss

  of said drive pulley 10 so that

  see it rotate freely On a lower side of said small diameter part 21 b is or are formed

  one or more projections 21 c On an upper part

  of said rotary assembly 20 for transmitting force by friction, a friction element 22 is fixed which rubs against the lower part of said drive pulley 10.

  On the upper side of said drive pulley -

  10, a first rotary assembly 30 is provided.

  taking a transmission disc 31, a clutch 32 and a clutch spring 33 Said transmission disc 31 comprises a boss locking hole 31 a in which said small diameter part 21 b and said projection 21 c

  of it are adjusted, a plurality of hooks of ver-

  rusting 31 b protruding from a predetermined height

  and a plurality of rod through holes 31c corresponding

  dant with said rod insertion hole 13.

  Said clutch 32 is locked by said hook

  chet 31 b of said transmission disc 31 Said clutch 32 is also provided with a plurality of rods 32 a which can be introduced through said rod through hole 31 c into said rod introduction hole 13,

  to slide up and down there, the li-

  mite for upward movement of clutch 32 being the position in which said clutch 32 is locked

by said hook 31 b.

  Said clutch spring 33 is disposed between said clutch 32 and said transmission disc 31 so that said clutch 32 can be raised to said locked position, so that normally said rod 32 a is disposed in said rod through hole 31 c of said transmission disc 31 However, when said clutch 32 is pushed down, said clutch rod

  32 a can be moved and inserted into said insertion hole

  translation of rod 13 of said drive pulley 10.

  On the upper side is arranged said second

  rotary assembly 40 in engagement with said boss 21 of the

  said rotary friction transmission assembly 20 to be thus driven by the friction force Said second rotary assembly 40 also comprises a rotary body 41, a tubular or hollow cam 42, a guide 43 and a torque change spring 44 Said rotary body 41 has a toothed part 41 a at its periphery and a plurality of guide supports 41 b extending downwards. Said cam 42 comprises an insertion hole, a boss 42 a which is arranged to rotate in the hollow part of said body 41 and into which is introduced the upper part of said small diameter part 21 b of said boss 21 and

  an inclined cam surface 42 b formed in its periphery.

  Said guide 43 comprises a cam guide projection 43 a which transmits the movement to said inclined cam surface 42 b and a plurality of guide grooves 43 b engaged with said guide supports 41 b Said guide 43 is thus limited to two heights Said spring 44 is

  disposed between said guide 43 and said transmission disc

sion 31.

  In order to create a space between said pulley

  drag 10 and said transmission disc 31, is provided

  a pulley washer 14 having a low coefficient of money -

tion between them.

  Figure 3 shows the drive device

  coil in assembled state in image search mode

  in reverse direction (RPS) thereof, when said drive pulley 10 is driven by a belt 52, said rotary friction motion transmission assembly is driven by the friction force by the friction element 22 which rubs against said drive pulley under the action of the force of said spring 44 Said second

  rotary assembly 40 is driven by this driving force

  frictionally Simultaneously, said first set

  rotary 30 is also driven by said driving force

friction drag.

  In the meantime, the rotary body 41 of the second rotary assembly 40 is brought into contact with a driven element.

  any such as a crazy pebble In such a case, if the

  that of the driven element is greater than the friction force between said spring 44 and said friction element 22, a

  slip appears on said friction element 22 A sa-

  see said second rotary assembly 40 is driven within the predetermined load range At this time, in the case of a clockwise drive, the cam guide projection 43 has guide 43 is positioned at the upper limit of the inclined cam surface 42 b formed on the cam 42 as shown in solid lines in Figure 4 so that said spring 44 is not compressed, so that the elastic force is relatively reduced therefore, since in this case said friction drive force is not

  important, it is capable of causing a low charge.

  However, in the case of a drive in the opposite direction

  milking clockwise, as shown in dotted lines in FIG. 4, said projection 43 a is moved to the lower limit position of said inclined cam surface 42 b so as to compress said spring 44,

  thus causing a significant elastic force By con-

  sequent, since, in this case, said friction drive force is relatively large so that

  said driven element can be driven in the direction

  milk clockwise due to increased torque

  as a result, a large load may be caused.

  As shown in Figure 4, in the reverse image search mode (RPS), as said projection 43a is moved along said inclined cam surface 42b, said projection 43a is compressed so that

  slippage of speed may be caused by said round

  delle pulley 14 shown in Figure 2 between the pou-

  drive link 10 and the rotary assembly driven by

  therefore, thanks to the action of the force of the compressed spring

  il mé, slip speed can be caused between said driven assembly and said pulley washer Therefore, in the reverse image search mode (RPS), the aforementioned problems encountered in the prior art can be solved. Furthermore, as shown in Figure 5,

  on the upper side of the clutch 32 of the first set

  rotatable ble 30, is arranged a lever shift element

  54 which is actuated as a lever by a slide 53.

  Said lever shift member 54 can also be

  operated in high speed scrolling mode (forward

  this fast or rewind) as an element in contact with a

  any separate mode change lever.

  Namely, since in the normal scrolling mode

  wrong, said lever shift member 54 is not action-

  born, said first rotary assembly 30 is not driven so that its operation can be neglected The second rotary assembly 40 is driven by the predetermined torque by the rotary force-transmitting element by friction 20 In addition, in the mode of high speed scrolling (fast forward and rewind), when said clutch 32 is lowered by said lever shift element 54,

  said rods 32 a are introduced into the through holes.

  sants of rod 31 c of said rotary assembly 20 in the rod insertion hole 13 of said drive pulley Consequently, said first rotary assembly 30 is directly driven by the motive force of said pulley

  and this driving force is transmitted to said whole ro-

  tative 20 So the latter is driven by the mo-

  regardless of the friction force generated by said torque change spring 44 Therefore,

  all of the rotary assemblies 20, 30 and 40 are

  dragged by motive force When said de-

  lever setting 54 is returned to its initial position, the clutch engagement of said first rotary assembly 30 with said drive pulley 10 is eliminated by

  therefore, said rotary assembly 20 and said second assembly

  seems rotary 40 are driven by the friction force.

  Thus, the coil driving device according to the pre-

  sente invention is of a variable torque type and uses a torque change method by increasing or reducing the pressure of the friction element by an inclined cam, which method comprises the following steps: 1 In the reproduction mode, the torque is generated by the friction element fixed on the pulley

  so that the tape is scrolled

done at normal speed

  2 In fast forward (F / F) and rewind modes

  swim (REW), when the shift element at

  lever 54 pushes clutch 22 by actuating

  ment of the slide 53, the clutch rod 32 is engaged with the transmission disc 31, so that the energy transmitted from the

  drive pulley 10 is transmitted to it

  ci without loss; 3 In reverse image search (RPS) mode, as shown in Figure 4, as said projection 43 a is moved along said inclined cam surface 42 b, said projection 43 a is compressed so that the sliding of speed can be caused by said pulley washer 14 represented in FIG. 2 between the driving pulley 10 and the rotatable assembly driven Consequently, thanks to the operations of the force of compressed spring and the sliding of speed between said

  driven assembly and said pulley washer By con-

  sequent, in the image search mode in the

  opposite direction (RPS), the aforementioned problems

  countered in the prior art can be resolved.

  According to the present invention, as described above

  sus, the reel drive device of a magnetosco-

  pe can carry out the drive by fric-

  tion, by varying the torque according to the direction of rotation, using the second rotary assembly equipped with the means

  torque change and direct drive by the

  this drive, using the first rotary assembly equipped with clutch means and auxiliary means of

  this The coil drive device of the pre-

  sente invention also allows the reduction of manufacturing cost and energy loss, and can increase productivity The present invention can also ensure the transmission of energy, thereby improving reliability

some products.

  Although a preferred embodiment of the invention

  vention has been described, it is obvious that modifications

  tions and variants can be made without leaving

  neither the spirit nor the scope of the invention.

Claims (1)

CLAIMS 1 Coil drive device of the variable torque type of a magnetic recording and reproducing device, characterized in that it comprises: coil drive means (10, 20) for selectively actuating the coils according to their direction of rotation, means (40) for producing a variable torque arranged on a shaft (51), and means (30) for changing the reel speed in order to change the speed of the reels, 2 Device for Variable torque type coil drive according to claim 1, characterized in that said means for producing variable torque comprises an inclined cam (42). 3 reel drive device of the variable torque type according to claim 2, characterized in that said means for producing a variable torque causes the speed slip by means of a pulley washer (14) relative to a transmission means energy (43 a) compressed by displacement of said inclined cam (42). 4 Coil drive device of the variable torque type according to any one of claims 1 to 3, characterized in that said coil speed changing means comprises a clutch element (32) and a lever (54) which is operated only in a desired mode. Variable torque type coil drive device according to any one of the claims   1 to 4, characterized in that said means for producing variable torque comprises a friction element (22) fixed on a drive pulley (10; 20).