Magnetic recording/reproducing apparatus having torque generator generating the most appropriate torque and rotation detecting function

A driving system of a magnetic recording/reproducing apparatus includes a motor, a pulley receiving rotation of the motor, a forward direction rotation body coaxially provided with the pulley, a reverse direction rotation body which always engages with the forward direction rotation body and rotates in the reverse direction, first and second reel stands which engage with respective reels of a cassette tape, and a moving rotation body which engages with the forward direction rotation body and the first reel stand in forward direction rotation, and engages with the reverse direction rotation body and the second reel stand in reverse direction rotation. A forward direction torque generating mechanism is provided between the forward direction rotation body and the moving rotation body and a reverse direction torque generating mechanism is provided between the reverse direction rotation body and the moving rotation body. The forward direction/reverse direction torque generating mechanisms include two friction transmitting members for generating torque suitable to constant speed run and high speed run, respectively. A reflection plate for detecting rotation of the first and second reel stands is fixed to either one of the forward direction rotation body or the reverse direction rotation body. A light emitting light receiving element for detecting rotation of the rotation plate is provided at a position facing to the reflection plate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to structure of a magnetic 
recording/reproducing apparatus having a torque generating function 
providing the most appropriate torque required when cassette tape is 
running at a constant speed and at a high speed, respectively. 
Furthermore, the present invention relates to structure of magnetic 
recording/reproducing apparatus having a function of determining a 
taking-up state and a taking-up finish state of cassette tape. 
2. Description of the Background Art 
Generally, in a magnetic recording/reproducing apparatus, when a tape is 
running at a constant speed in recording/reproducing, a reel stand taking 
up the tape is rotated with relatively low torque (in a compact cassette, 
generally about 35 g.cm), and when the tape is running at a high speed 
such as in fast forwarding/rewinding, the reel stand is rotated for taking 
up with relatively high torque (in a compact cassette, generally about 
70-100 g.cm). Accordingly, a low torque generating mechanism and a high 
torque generating mechanism are individually provided in an apparatus, and 
the constant speed running and the high speed running of cassette tape 
have been implemented by transmitting torque generated by each mechanism 
to a predetermined reel stand. 
In such a tape running mechanism, however, the number of parts is large and 
the loss of space is great, which makes it difficult to make apparatus 
smaller and to reduce manufacturing cost. 
Magnetic recording/reproducing apparatus which solves such disadvantages 
include one disclosed in Japanese Utility Model Publication No. 2-6519. In 
the magnetic recording/reproducing apparatus, structure is disclosed in 
which generating means for low torque and generating means for high torque 
are provided on the same axis. FIG. 21 is a plan structural view of a 
magnetic recording/reproducing apparatus disclosed in the published 
application, and FIG. 22 is a cross sectional structural view of the reel 
stand driving mechanism shown in FIG. 21. A conventional magnetic 
recording/reproducing apparatus includes a driving motor 102, a pulley 122 
to which the rotation force of the motor is transmitted through belt 120, 
a supply reel stand 103 and a take-up reel stand 104 engaging with 
cassette tape, and a reel stand driving mechanism for transmitting the 
rotation force transmitted to the pulley 122 to a predetermined supply 
reel stand 103 or take-up reel stand 104. The reel stand driving mechanism 
includes an intermediate gear 123 and a driving gear 125 provided on the 
same axis as pulley 122. A first sliding clutch 124 is interposed between 
pulley 122 and intermediate gear 123, and a second sliding clutch 126 is 
provided between intermediate gear 123 and driving gear 125. The driving 
gear 125 and the intermediate gear 123 are pressed onto pulley 122 by a 
spring 127 through the first and second sliding clutches 124, 126. 
In operation, in the constant running of tape requiring low torque, the 
rotation force of pulley 122 is reduced to predetermined low torque 
through first sliding clutch 124 and second sliding clutch 126, and then 
transmitted to the take-up reel stand 104 side by driving gear 125. When 
the tape is running at a high speed requiring high torque, the rotation 
force of pulley 122 is slightly reduced and transmitted to an intermediate 
gear 123 through first sliding clutch 124, and furthermore transmitted to 
take-up reel stand 104 or supply reel stand 103 through a pivoting gear 
129. The pivoting gear 129 then simultaneously engages with intermediate 
gear 123 and driving gear 125. The second sliding clutch 126 is thus fixed 
not to function. 
A conventional magnetic recording/reproducing apparatus, however, has the 
following problems. 
(1) Firstly, it is difficult to set a value of high torque extracted from 
pivoting gear 129 and a value of low torque extracted from driving gear 
125 at the most appropriate values, respectively. This comes from the 
structure in which first sliding clutch 124 and second sliding clutch 126 
are pressed by a single compression spring 127. That is to say, in first 
and second sliding clutches 124 and 126, felt which is generally formed of 
wool or the like is sandwiched between two rotating bodies, which is 
pressed by a spring in one direction to transmit desired torque by the 
sliding friction. Accordingly, the transmitted torque is affected by a 
friction factor between the two rotating bodies and the felt, and the 
compressive force supplied to the two rotating bodies. The friction factor 
between the two rotating bodies and the felt has a large variety, which is 
largely affected by the environments, especially by humidity. Accordingly, 
it is necessary to precisely set the load of the compression spring in 
setting transmission torque. However, it is difficult when compressing two 
sliding clutches 124 and 126 with a single compression spring 127 as 
described above to make setting so that the most appropriate compressive 
force is applied to each. Accordingly, in a conventional structure, it has 
been difficult to set values of both of high and low torque at the most 
appropriate values. 
(2) Secondly, in order to obtain high torque, it must be extracted through 
first sliding clutch 124 from pulley 122 through pivoting gear 129 which 
simultaneously meshes with intermediate gear 123 and driving gear 125. 
Pivoting gear 129 must be simultaneously brought into mesh with 
intermediate gear 123 and driving gear 125 from a separated condition. If 
intermediate gear 123 and driving gear 125 are in alignment, the mesh can 
be smoothly made, but if they are not in alignment, pivoting gear 129 must 
be pressed so that either one of the gears is relatively moved to bring 
tooth surfaces of the two gears in alignment. However, second sliding 
clutch 126 having friction force is interposed between intermediate gear 
123 and driving gear 125. Accordingly, for bringing pivoting gear 129 into 
mesh with both gears, it must be pressed with force which overcomes the 
friction force of second sliding clutch 126. Accordingly, if it is made to 
obtain the pivoting force for pivoting gear 129 utilizing the rotation 
force from the driving motor, the motor is required for high driving 
force, resulting in an increase in cost. Also, when the mesh is not made 
smoothly because of such conditions as described above when pivoting gear 
129 is brought into mesh, abnormal sounds such as gear noise may occur. 
A conventional magnetic recording/reproducing apparatus has an auto stop 
function of detecting a tape take up finish state of cassette tape and 
automatically stopping a motor which drives reels. FIG. 23 is a plan 
structural schematic view showing structure of a tape driving portion of a 
conventional magnetic recording/reproducing apparatus, FIG. 24 is a 
sectional structure diagram taking along the cut line E--E in FIG. 23, and 
FIG. 25 is a plan structure schematic view taking along the arrow F--F of 
FIG. 24. FIG. 23 and FIG. 25 are a top view and a bottom view with respect 
to each other. Referring to FIGS. 23 through 25, with a cassette 75 
attached, it engages with two reel stands 76 and 77. Magnetic tape of 
cassette 75 is provided so that it passes between one capstan 78 and a 
pinch roller 80 and between the other capstan 79 and pinch roller 81. The 
shown magnetic recording/reproducing apparatus has a driving mechanism 
capable of constant running in a forward direction and constant running in 
a reverse direction. In running at a constant speed in the forward 
direction, the tape is sandwiched and held between capstan 78 and pinch 
roller 80, which is fed in a normal direction "a" with take up rotation 
operation of a FOR reel stand 76 in the normal direction X and the 
constant speed rotation operation of capstan 78 and pinch roller 80. 
In reverse direction constant speed running, the magnetic tape is 
sandwiched and held between capstan 79 and pinch roller 81, which is fed 
in the reverse direction "b" with the reverse direction rotation Y of a 
REV reel stand 77 and the constant speed reverse direction rotation of 
capstan 79 and pinch roller 81. 
A conventional magnetic recording/reproducing apparatus has an automatic 
stop mechanism for automatically stopping operation of the apparatus when 
a terminal end of the tape in run is reached. The detecting mechanism for 
detecting the terminal end of tape has structure as described below. 
First, a reflection panel 70 is provided on the same axis as that for FOR 
reel stand 76. As shown in FIG. 25, in reflection panel 70, portions with 
high optical reflectance ratio and portions with low reflectance are 
alternately arranged for every constant angle around the rotation axis. A 
light emitting light receiving element 71 is provided at a position facing 
rotation panel 70. Furthermore, a rotation detecting device for 
electrically detecting rotation operation of rotation panel 70 is 
connected to light emitting light receiving element 71. 
FIG. 26 is a schematic diagram showing positional relationship between 
rotation panel 70 and light emitting light receiving element 71, and FIG. 
27 is a block diagram for describing a rotation detecting device for 
detecting the rotation movement of rotation panel 70. Light emitting light 
receiving element 71 emits light to the rotating panel and receives light 
reflected from reflection panel 70 to convert its magnitude into an 
electrical signal. A frequency/voltage converter 72 converts the frequency 
of a periodical signal supplied from light emitting light receiving 
element 71 into voltage to output an output voltage v.sub.1. A comparator 
73 receives the output voltage v.sub.1 from frequency/voltage converter 
72, compares it with an output voltage v.sub.0 which is outputted from 
frequency/voltage converter 72 in the case where the frequency of a signal 
outputted from light emitting light receiving element 71 is 0, and if 
v.sub.1 -v.sub.0 &lt;0, outputs High, and if v.sub.1 -v.sub.0 =0, outputs 
Low. Furthermore, a tape take up determining device 74 receives the output 
of comparator 73, and makes a determination that the tape is being taken 
up if the output is High and that taking up of the tape is finished if the 
output is Low. Then, when a determination is made by tape take up 
determining device 74 that the tape has been taken up, the rotation of the 
driving motor is stopped. 
However, in such a mechanism for detecting tape take up states as described 
above, there has been a problem that a case may occur in which the 
automatic stop mechanism does not operate in spite of a fact that the tape 
run should be stopped. It is described referring to FIGS. 28 and 29. FIG. 
28 is a schematic diagram of the normal direction tape drive indicating 
operation conditions of the tape driving system in the normal direction 
constant run and FIG. 29 is a schematic diagram of the reverse direction 
tape drive. 
First, referring to FIG. 28, in the forward direction constant run, the 
tape is fed from the REV reel stand 77 side to the FOR reel stand 76 side 
at a constant speed by FOR reel stand 76 always rotating in the X 
direction, capstan 78 feeding magnetic tape in the same direction and 
pinch roller 80, which is taken up by the reel of cassette tape 75 
engaging with FOR reel stand 76. Imagine a case where the rotation of FOR 
reel stand 76 is stopped due to some abnormality in the forward direction 
constant speed run. In this case, capstan 78 continues to feed the tape in 
the forward direction in order to maintain the rotational movement. On the 
other hand, when the rotation of FOR reel stand 76 is stopped, the 
rotation of reflection panel 70 coaxially provided is also stopped. Then, 
the above-described rotation detecting means determines that the tape has 
been taken up, and then the automatic stop mechanism operates to stop the 
driving motor. The rotation operation of capstan 78 thus stops, too. 
Referring to FIG. 29, however, in the reverse direction constant speed run, 
a normal stopping operation is not carried out as in the forward direction 
run. That is to say, in the reverse direction constant speed run, REV reel 
stand 77 rotates in the Y direction and the tape is fed at a constant 
speed in the same direction by capstan 79 and pinch roller 81. The 
magnetic tape is thus taken up at a constant speed from the reel side 
engaging with FOR reel stand 76 to the reel side engaging with REV reel 
stand 77. 
Imagine that the rotation of REV reel stand 77 is stopped due to some 
abnormality. Capstan 79 and pinch roller 81 maintains the rotational 
movement even when the rotation of REV reel stand 77 stops, to 
continuously forwarding the magnetic tape. Then, FOR reel stand 76 also 
maintains the rotation movement with the tape feeding operation of the 
capstan 79 and pinch roller 81. Accordingly, reflection panel 70 provided 
in FOR reel stand 76 still maintains the rotating state. Therefore, the 
rotation detecting device makes a determination that the tape is being 
taken up not to operate the automatic stop mechanism. Accordingly, the 
magnetic tape fed by capstan 79 and pinch roller 81 is continuously fed 
out toward the reel engaging with REV reel stand 77, with the result that 
the magnetic tape is continuously pulled out from cassette tape 75. In 
this case, a problem occurs in which the magnetic tape is damaged to be 
unusable. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a magnetic 
recording/reproducing apparatus having a torque generating mechanism for 
generating the most appropriate torque for driving a tape according to 
respective operation modes of a cassette tape. 
It is another object of the present invention to miniaturize a torque 
generating mechanism of a magnetic recording/reproducing apparatus. 
Furthermore, it is still another object of the present invention to provide 
a magnetic recording/reproducing apparatus provided with a rotation 
detecting mechanism which detects rotational abnormality when tape reels 
are running in forward/reverse directions and stops the tape running. 
In one aspect of the present invention, a magnetic recording/reproducing 
apparatus includes a pair of first and second reel members engaging with 
cassette tape for taking up the magnetic tape of the cassette tape in a 
predetermined direction, a motor producing rotation force, a forward 
direction torque generating mechanism linked to the motor, a reverse 
direction torque generating mechanism engaging with the forward direction 
torque generating mechanism, and a rotation force transmitting mechanism 
intervening among the forward direction torque generating mechanism, the 
reverse direction torque generating mechanism, and the first and second 
reel members. 
The forward direction torque generating mechanism includes a pulley for 
receiving the rotation force from the motor, a first rotating body 
provided coaxially with the pulley, first friction transmitting mechanism 
intervening between the pulley and the first rotating body for reducing 
the rotation force which the pulley receives to a predetermined value and 
transmitting it to the first rotating body, a second rotating body 
provided coaxially with the pulley, and second friction transmitting 
mechanism intervening between the first rotating body and the second 
rotating body for further reducing the rotating force of the first 
rotating body and transmitting the force to the second rotating body. 
The reverse direction torque generating mechanism includes a fifth rotating 
body which engages with the first rotating body of the forward direction 
torque generating mechanism and rotates in the opposite direction to the 
first rotating body. 
The rotation force transmitting mechanism includes a third rotating body 
which engages simultaneously with the second rotating body of the forward 
direction torque generating mechanism and the first reel member in the 
constant speed run of a recording/reproducing mode of cassette tape for 
transmitting the rotation force of the second rotating body to the first 
reel member, and a fourth rotating body which simultaneously engages with 
the first rotating body of the forward direction torque generating 
mechanism and the first reel member in high speed run of a fast forwarding 
mode of the cassette tape to transmit the rotation force of the first 
rotation body to the first reel member, and in the high speed run of the 
rewinding mode, engages simultaneously with the fifth rotating body of the 
reverse direction torque generating mechanism and the second reel member 
to transmit the rotation force of the fifth rotating body to the second 
reel member. 
In the magnetic recording/reproducing apparatus, a first rotating body 
generating high torque and a second rotating body producing low torque are 
independently provided wherein rotation force is transmitted through a 
fourth and third rotating bodies which engage with the first and second 
rotating bodies, respectively. The rotation force set at a predetermined 
high torque value by the first friction transmitting mechanism is 
transmitted from the first rotating body to the fourth rotating body. 
Rotating force set at a predetermined low torque value by the second 
friction transmitting mechanism is transmitted from the second rotating 
body to the third rotating body. The transmission of rotation force is 
carried out by engagement of each single pair of rotation bodies, so that 
it is smooth and does not produce noise. 
In the second aspect of the present invention, a magnetic 
recording/reproducing apparatus includes a pair of first and second reel 
members which engage with cassette tape for taking up magnetic tape of the 
cassette tape in a predetermined direction, a motor producing rotation 
force, forward direction torque generating mechanism linking to the motor, 
reverse direction torque generating mechanism linking to the forward 
direction torque generating mechanisms, and a rotation force transmitting 
mechanism linking to the forward direction and reverse direction torque 
generating mechanisms. 
The forward direction torque generating mechanism includes a pulley 
receiving the rotation force from the motor, a first rotating body 
provided coaxially with the pulley, a first friction transmitting 
mechanism intervening between the pulley and the first rotating body for 
reducing the rotating force received by the pulley to a predetermined 
value and transmitting the force to the first rotating body, a second 
rotating body provided coaxially with the pulley, and a second friction 
transmitting mechanism intervening between the first rotating body and the 
second rotating body for further reducing the rotation force of the first 
rotating body and transmitting the force to the second rotating body. 
The reverse direction torque generating mechanism includes a fifth rotating 
body engaging with the first rotating body of the forward direction torque 
generating mechanism and rotates in the opposite direction to the first 
rotating body, and a sixth rotating body which is provided on the same 
axis as the fifth rotating body, engages with the second rotating body of 
the forward direction torque generating mechanism and rotates in the 
opposite direction to the second rotating body. 
The rotation force transmitting mechanism includes a third rotating body 
which engages simultaneously with the second rotating body of the forward 
direction torque generating mechanism and the first reel member in the 
forward direction constant speed run of the cassette tape for transmitting 
the rotation force of the second rotating body to the first reel member, 
and in the reverse direction constant speed run of the cassette tape, 
engages simultaneously with the sixth rotating body of the reverse 
direction torque generating mechanism and the second reel member for 
transmitting the rotation force of the sixth rotating body to the second 
reel member, and a fourth rotating body which, in the forward direction 
high speed run of the cassette tape, simultaneously engages with the first 
rotating body of the forward direction torque generating mechanism and the 
first reel member for transmitting the rotation force of the first 
rotating body to the first reel member, and in the reverse direction high 
speed run simultaneously engages with the fifth rotating body of the 
reverse direction torque generating mechanism and the second reel member 
for transmitting the rotation force of the fifth rotating body to the 
second reel member. 
In the above-described invention, the sixth rotating body which engages 
with the first rotating body and rotates in the opposite direction is 
provided in the reverse direction torque generating mechanism to enable 
the so-called automatic reverse mechanism capable of play in the reverse 
direction running of tape. 
In the third aspect of the present invention, a magnetic 
recording/reproducing apparatus has recording/reproducing modes in which 
provided cassette tape runs at a constant speed in a forward direction and 
a reverse direction. It has a pair of first and second reel members 
engaging with the cassette tape for taking up magnetic tape of the 
cassette tape in a predetermined direction, a motor producing rotation 
force, and a pulley receiving the rotation force from the motor. 
Furthermore, a second rotating body which receives the rotation force of 
the pulley to rotate is provided on the same axis as that of the pulley. A 
sixth rotating body which rotates in the opposite direction to the second 
rotating body engages with the second rotating body. Furthermore, the 
magnetic recording/reproducing apparatus has a third rotating body. The 
third rotating body simultaneously engages with the second rotating body 
and the first reel member in the forward direction running of the cassette 
tape to transmit the rotation force of the second rotating body to the 
first reel member. It simultaneously engages with the sixth rotating body 
and the second reel member to transmit the rotation force of the sixth 
rotating body to the second reel member when the tape of the cassette tape 
is running in the reverse direction. Also, it is provided with a rotation 
detecting device having a rotation detecting body which rotates engaging 
with either one of the second rotating body or the sixth rotating body and 
a detecting device for electrically detecting the rotation movement of the 
rotation detecting body. 
In the magnetic recording/reproducing apparatus according to the present 
invention, the rotation detecting body is provided so as to rotate 
engaging with either one of the second rotating body or the sixth rotating 
body. The second rotating body is linked to the first reel member with the 
third rotating body intervening therebetween when the tape is running in 
the forward direction. Accordingly, when the first reel member stops due 
to some trouble, the second rotating body also stops. In the reverse 
direction running of the cassette tape, it is linked to the second reel 
member through the sixth rotating body and the third rotating body. 
Accordingly, when the second reel member stops due to some trouble, the 
second rotating body also stops. Accordingly, when the rotation detecting 
body is attached to the second rotating body, the second rotating body and 
the rotation detecting body stop to determine that the cassette tape is in 
a standstill state with abnormal stop of the first and second reel members 
in both of the forward direction running and the reverse direction 
running. 
Also when the rotation detecting body is attached to the sixth rotating 
body, the same function is effected. That is to say, in the forward 
direction run, the sixth rotation body engages with the second rotation 
body which rotates being linked to the first reel member with the third 
rotating body intervening therebetween. Accordingly, when the first reel 
member stops, the standstill state is transmitted through the third 
rotating body and the second rotating body. In the reverse direction run, 
the rotating state is transmitted through the third rotating body with 
stop of the second reel member since it is linked to the second reel 
member with the third rotating body intervening therebetween. Accordingly, 
in both of the cases of the forward direction running and the reverse 
direction running, the sixth rotating body stops with abnormal stop of the 
first and second reel members. Accordingly, the rotation detecting body 
attached to the sixth rotation body also stops to determine a standstill 
state of the cassette tape.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A magnetic recording/reproducing apparatus according to the present 
invention has a so-called automatic reverse mechanism. It can implement a 
forward direction recording/playback mode (a FP mode: a forward play 
state), a forward direction fast forwarding mode (a FF mode: a fast 
forward state), a reverse direction recording/playback mode (a RP mode: a 
reverse play state) and a rewinding mode (REW mode: a rewinding state). 
First, referring to FIG. 5, the magnetic recording/reproducing apparatus 
has its main parts provided on a main chassis 1. A drive block 2 has 
rotating parts and the like on a drive block plate 2a and is attached to 
the main chassis 1 with screws. 
A motor 7, a FOR fly wheel 5 supported by a FOR capstan axis 5a, and a REV 
fly wheel 6 supported by a REV capstan axis 6a are arranged on main 
chassis 1. A fly belt 8 is suspended over a motor pulley 7a which is 
affixed to an output axis of motor 7, a FOR fly wheel 5 and a REV fly 
wheel 6. Motor 7 always rotates in a counterclockwise direction. FOR 
capstan axis 5a and FOR fly wheel 5 rotate in a counterclockwise direction 
and a REW capstan axis 6a and REV fly wheel 6 rotate in a clockwise 
direction. 
A pulley 11 supported by a drive axis 10 is rotatably provided on the drive 
block plate 2a of drive block 2. A drive belt 9 is suspended over pulley 
11 and a fly pulley 5b of FOR fly wheel 5. Pulley 11 thus always rotates 
in the counterclockwise direction. Furthermore, a substantially T-shaped 
play idler lever 12 attached to an axis 2b and an also substantially 
T-shaped FF/REW idler lever 13 are coaxially provided on drive block plate 
2a. The play idler lever 12 and the FF/REW idler lever 13 are provided 
pivotably around axis 2b. 
Next, mainly referring to FIG. 1, a FOR pinch roller block 14 and a REV 
pinch roller block 15 are symmetrically provided on main chassis 1. The 
FOR pinch roller block 14 is provided pivotably about axis la and the REV 
pinch roller block 15 is provided pivotably about axis 1b. A head plate 16 
is guided by axes 1c and 1d provided on main chassis 1 to be 
reciprocatable in the direction of the arrows A and B, which is always 
energized in the arrow B direction by a spring (not shown). A magnetic 
head (not shown) is provided on head plate 16, which operates to make an 
appropriate contact with magnetic tape of cassette tape when head plate 16 
moves in the arrow A direction resistant against the spring force by the 
rotation of a first cam (not shown). The axes 1c and 1d are provided on a 
perpendicular bisector of a segment connecting a rotation center axis 2c 
of FOR reel stand 3 and a rotation central axis 2d of REV reel stand 4. A 
guide hole 16a is provided at a tip of head plate 16. Guide hole 16a 
includes long hole 16a-1 forbidding movement of a pin 12a, which is 
provided in play idler lever 12, in the directions of arrows C and D in 
the figure, oblique sides 16a-2, 16a-3 and an opening 16a-4 which enables 
movement of pin 12a in the directions of the arrows C and D. 
Reverse plate 17 is guided by axes 16b and 16c provided in head plate 16 to 
be reciprocatable in the directions of the arrows C and D. The reverse 
plate 17 is always energized by a spring (not shown) in the direction of 
the arrow C, which is movable in the arrow D direction with operation of a 
second cam (not shown). As shown in FIG. 1, in a standstill state, reverse 
plate 17 is positioned on the arrow C direction side. 
Next, a switching mechanism to the FF/REW mode will be described. An FF 
lever 18 for switch to the FF mode and an REW lever 19 for switch to the 
REW mode are guided for reciprocating movement in directions of the arrows 
A and B, respectively by axes 1e, 1f and axes 1g and 1h provided in main 
chassis 1. Both of the levers 18 and 19 are energized in the arrow B 
direction by a spring (not shown). The FF lever 18 and REW lever 19 are 
provided symmetrically about a perpendicular bisector of a segment 
connecting rotation centers of both reel stands 3 and 4. FF lever 18 has a 
protruding portion 18a in the direction of the arrow A and similarly REW 
19 has a protruding portion 19a. The protruding portion 18a of FF lever 18 
faces a left arm 13a of FF/REW idler lever 13 and the protruding portion 
19a of REW lever 19 faces a right arm 13b of FF/REW idler lever 13. 
Furthermore, FF operation parts and REW operation parts (not shown) are 
provided corresponding to each other on the arrow B side of FF lever 18 
and REW lever 19. 
FF/REW idler lever 13 is provided pivotably on axis 2b provided on drive 
block plate 2a. A lever portion of FF/REW idler lever 13 has a stepped 
shape coupled by coupling portion 13c. A coil portion of FF/REW torsion 
spring 22 is put around the outer periphery surface 13d of a baring 
portion of axis 2b. Both arms of torsion spring 22 sandwich and hold 
coupling portion 13c of FF/REW idler lever 13. Protruding portion 2i 
protruding from a surface of drive block plate 2a exists between coupling 
portion 13c of FF/REW idler lever 13 and the outer periphery surface 13d 
of the bearing portion. The width of coupling portion 13c of FF/REW idler 
lever 13 and the width of the protruding portion 2i of drive block plate 
2a are made equal to each other. By such structure, FF/REW idler lever 13 
is maintained at a position allowing no pivoting neither in clockwise nor 
counterclockwise direction by the effect of torsion spring 22. 
Next, the rotation transmitting system is described. In the rotation 
transmitting system, all the rotation parts except the motor, the fly 
wheel, the pinch roller belt are provided as a block on drive block 2. 
Referring to FIGS. 3, 4 and 6, drive block plate 2a of drive block 2 has 
an integrally formed boss 2g having a through hole 2h for a screw for 
attachment to main chassis 1. Furthermore, axis 2b for play idler lever 12 
and FF/REW idler lever 13, axis 2c for FOR reel stand 3, axis 2d for REV 
reel stand 4 and axis 2e for a reverse gear and a REW gear are provided on 
drive block plate 2a and furthermore a bearing of drive axis 10 is 
provided thereon. The pitch between axis 2c of FOR reel stand 3 and axis 
2d of REV reel stand 4 is 42.5 mm, for example, which coincides with the 
reel pitch of a compact cassette tape. The axis 2b is equally distant from 
the rotation central axes 2c and 2d of both reel stands 3 and 4, and 
positioned on the arrow B side from the bearing of drive axis 10. 
Furthermore, axis 2e for the reverse gear and the bearing portion of drive 
axis 10 are provided symmetrically about the perpendicular bisector of a 
line connecting rotation central axes 2c and 2d of FOR reel stand 3 and 
REW reel stand 4. Drive block 2 is fixed with screws at a predetermined 
position of main chassis 1 through bosses 2g. Drive block 2 is provided so 
that both reel axes 2c and 2d are arranged at predetermined set positions 
for both capstan axes 5a and 6a. For example, the distance between the 
axis line of both reel axes 2c and 2d and the axis line of both capstan 
axes 5a and 6a is 31.3 mm. 
Referring to FIGS. 3 and 6, friction block 60 will be described. Drive axis 
10 is rotatably inserted into bearing 2f provided in drive block plate 2a. 
Respective rotating parts are provided on a portion protruding downwards 
(the direction of the arrow E) and at a portion protruding upwards of the 
drive axis 10 (the direction of the arrow F) from drive block plate 2a. 
First, at a lower portion of drive axis 10, a spring bearing 30 is put with 
pressure and fixed at a lower portion of drive axis 10. The lower end 
surfaces of spring bearing 30 and drive axis 10 coincide with each other. 
Then, drive axis 10 and spring bearing 30 integrally rotate. A first 
compression spring 32 is provided on an upper surface of a flange of 
spring bearing 30. A friction plate 31 pushes down first compression 
spring 32 upon the upper surface of spring bearing 30, and a central 
portion of friction plate 31 is attached movably upwards and downwards to 
outer peripheral surface 30b of pressure insert portion 30a of spring 
bearing 30. First frictional member 33 is provided on an upper surface of 
friction plate 31, and pulley 11 is further attached on the upper surface 
thereof. After attaching pulley 11 on drive axis 10, a stop washer 34 is 
mounted to a groove 10a provided in drive axis 10. A detent (not shown) is 
provided between friction panel 31 and spring bearing 30, and friction 
panel 31 and spring bearing 30 integrally rotate. The rotation force is 
transmitted from motor 7 to pulley 11 by drive belt 9. The rotation of 
pulley 11 is transmitted to friction panel 31, spring bearing 30 and 
rotation axis 10 through the first friction member 33. The load of the 
first compression spring 32 is supported between spring bearing 30 and 
pulley 11 supported by stop washer 34. Then, a first maximum transmission 
torque (high torque) is set by first friction member 33 formed of felt 
such as wool and first compression spring 32. The first maximum 
transmission torque is appropriate torque to run tape at a high speed, 
which is 80 g.cm, for example. If it is assumed that torque transmitted 
from motor 7 to pulley 11 is 100 g.cm, torque of 20 g.cm is canceled by 
slip between pulley 11 and friction panel 31. The above-described 
structure is referred to as the first friction mechanism. The first 
maximum transmission torque set by the first friction mechanism is 
transmitted to the upper side of bearing 2f by drive axis 10. 
Next, the second friction mechanism located on the upper side of bearing 2f 
will be described. A flat washer 40 (product name: Polyslider Washer) 
formed of low friction member is attached to drive axis 10 upwardly 
protruding from bearing 2f of drive block plate 2a. Next, FF gear 35 is 
pressed in around drive axis 10. The FF gear 35 (a first rotating body) is 
provided so that the upper surface thereof and the upper end portion of 
drive axis 10 coincide with each other. FF gear 35 rotates integrally with 
drive axis 10. Subsequently, the clearance in the thrust direction of 
friction block 60 is adjusted. The clearance in the thrust direction 
occurs because of the difference between the whole length of drive axis 10 
and the whole length of FF gear 35, bearing 2f, washers 40, 34, pulley 11 
and spring bearing 30 attached to drive axis 10. The clearance in the 
thrust direction is adjusted to about 0.05-0.2 mm, for example. After 
adjusting the clearance in the thrust direction, second frictional member 
39 is provided on an upper surface of FF gear 35. Furthermore, a play gear 
37 (a second rotating body) is provided on an upper surface of the second 
frictional member 39. Play gear 37 has a gear portion 37a with a large 
diameter and a gear portion 37b with a small diameter. A second 
compression spring 38 is provided in an upper surface concave portion of 
play gear 37, and a spring bearing plate 36 is pressed in and fixed around 
outer peripheral surface 35d of the press-in portion 35b of FF gear 35 
thereupon. With such structure, the second friction mechanism is 
configured. FF gear 35 rotates integrally with drive axis 10, and play 
gear 37 rotates with a predetermined rotating force through the second 
frictional member 39. The load of second compression spring 38 is 
supported by spring bearing plate 36 and FF gear 35. Then, the second 
maximum transmission torque (low torque) is set by the second frictional 
member 39 and the second compression spring 38. The second maximum 
transmission torque has a value lower than that of the first maximum 
transmission torque, in which the torque is set to a value necessary for 
running tape at a constant speed. The value is 35 g.cm, for example. If 
the maximum torque of the first friction mechanism is 80 g.cm as described 
above, then the torque is reduced by 45 g.cm by the second friction 
mechanism. 
In this way, the first and second friction mechanisms are provided 
coaxially on drive axis 10. And they are provided separatedly above and 
below bearing 2f and drive block plate 2a interposed therebetween. 
Accordingly, the diversions of respective rotating bodies do not affect 
with each other. 
In summary, in operation of the first and second friction mechanisms, the 
rotation force transmitted from motor 7 to pulley 11 is limited to the 
first torque suitable to run tape at a high speed by the first friction 
mechanism, and the first torque is transmitted to FF gear 35 through 
friction panel 31, spring bearing 30 and drive axis 10. Predetermined high 
torque can be obtained by extracting the first torque from FF gear 35. 
Next, the rotation force transmitted to FF gear 35 is limited to the 
second torque suitable to run tape at a constant speed by the second 
friction mechanism and transmitted to play gear 37. Accordingly, 
predetermined low torque can be obtained by extracting the rotation force 
from play gear 37. 
FF gear 35 which is a drive source of the high torque and play gear 37 
which is a drive source of the low torque are provided adjacent each other 
with extremely thin second friction member 39 therebetween. The diameters 
of FF gear 35 and play gear 37 are equal to each other. By such structure, 
the entirety of friction block 60 is made compact. Accordingly, the 
rotation transmitting system engaging with the friction block 60 is also 
made compact. 
Next, the structure of the reel portion will be described. FOR reel stand 3 
and REV reel stand 4 have blade portions 3c and 4c engaging with reel hubs 
of cassette tape to take up the tape. They are rotatably attached to axes 
2c and 2d provided in drive block plate 2a. In FOR reel stand 3 and REV 
reel stand 4, respective large-diameter gears 3a and 4a and small-diameter 
gears 3b and 4b are coaxially and integrally provided. Both reel stands 3 
and 4 are attached to axes 2c and 2d with appropriate clearance with 
respect to drive block plate 2a by stop washers inserted into grooves 
provided on axes 2c and 2d. Furthermore, both reel stands 3 and 4 are 
forbidden to move along axes 2c and 2d. Large-diameter gears 3a and 4a of 
the reel stands mesh with small-diameter gear 20b of play idler gear 20 
(the third rotating body) to run tape at a constant speed, and the 
small-diameter gears 3b and 4b mesh with large-diameter gear 21a of FF/REW 
idler gear 21 (the fourth rotating body) to run tape at a high speed. 
Next, the mechanism related to reverse direction running of the tape is 
described. The mechanism includes REW gear 50 (the fifth rotating body) 
and reverse gear 51 (the sixth rotating body). An axis 2e is provided in a 
standing manner at a predetermined position of drive block plate 2a. REW 
gear 50 is attached rotatably to axis 2e. After putting REW gear 50 
through axis 2e, a stop washer is incorporated in the groove provided in 
axis 2e, and REW gear 50 is restrained to move up and downwards with 
permitted appropriate clearance in the longitudinal direction of axis 2e. 
Furthermore, reverse gear 51 is inserted through axis 2e and a stop washer 
is incorporated at the upper end of axis 2e. Reverse gear 51 is also 
permitted to have appropriate clearance in the axis direction of axis 2e. 
REW gear 50 and the large-diameter portion 51a of reverse gear 51 have 
almost the same diameter. REW gear 50 always mesh with FF gear 35 and 
large-diameter gear 51a of reverse gear 51 always mesh with the 
large-diameter gear 37a of play gear 37. REW gear 50 thus rotates in the 
opposite direction to that of FF gear 35 and reverse gear 51 rotates in 
the opposite direction to the direction of rotation of play gear 37. 
Furthermore, the mechanism of play idler lever 12 and FF/REW idler lever 13 
is described. Referring to FIGS. 2 and 6, FF/REW idler lever 13 is 
pivotably inserted through axis 2b provided in drive block plate 2a 
together with FF/REW torsion spring 22. Idler lever 13 secures appropriate 
clearance in the thrust direction with a stop washer attached in groove 
2b-1 provided in axis 2b, which is also restrained its up and down 
movement. Furthermore, play idler lever 12 is attached to axis 2b. Play 
idler lever 12 is provided with a snap hit portion (having structure in 
which a stopper portion is provided at a tip portion of an elastic 
portion. Not shown). When it is pushed down to a predetermined position, 
the snap hit portion is locked to drive lock plate 2a. With drive block 2 
attached to main chassis 1, upwards movement of play idler lever 12 is 
restrained by the lower surface of main chassis 1. At tip portions of play 
idler lever 12 and FF/REW idler lever 13, play idler gear 20 and FF/REW 
idler gear 21 having two step gears are rotatably attached through 
respective rotation axes 12d and 13e. Idler gear 20 and FF/REW idler gear 
21 are restrained to move up and down while maintaining appropriate 
clearance in the thrust direction by the stop washer with respect to 
respective rotation axes 12d and 13e. The pivoting centers of play idler 
lever 12 and FF/REW idler lever 13 are positioned at axis 2b as described 
above, wherein the distance l.sub.1 from the pivoting center to the 
rotation center of play idler gear 20 and the distance l.sub.2 from the 
pivoting center to the rotating center of FF/REW idler gear 21 are set 
almost equal to each other. However, strictly speaking, l.sub.2 is larger 
than l.sub.1. The large-diameter gear 20a of play idler gear 20 and the 
large-diameter gear 21a of FF/REW idler gear 21 are made to have the same 
diameter. 
Next, the positional relationship in the height direction of respective 
gears will be described. Large-diameter gear 21a of FF/REW idler gear 21 
is set at the same height as small-diameter gear 3b of FOR reel stand 3 
and small-diameter gear 4b of REW reel stand 4. Small-diameter gear 21b of 
FF/REW idler gear 21 is provided at the height same as FF gear 35 and REW 
gear 50 of friction block 60. On the other hand, large-diameter gear 20a 
of play idler lever 20 is set at the height same as small-diameter gear 
37b of play gear 37 and small-diameter gear 51b of reverse gear 51. 
Small-diameter gear 20b of play idler gear 20 is set at the same height as 
large-diameter gear 3a of FOR reel stand 3 and large-diameter gear 4a of 
REW reel stand 4. 
Next, the tape take-up detecting mechanism is described. Referring to FIGS. 
1, 3, 5 and 6, reflection panel (rotation detecting body) 70 is provided 
on the same axis as that of reverse gear 51 (the sixth rotating body) for 
axis 2e, and rotates integrally with reverse gear 51. Two kinds of 
portions with different light reflectance ratios are arranged alternately 
for a predetermined angle around the central point of the disk on the 
surface of rotating plate 70. A light emitting light receiving element 71 
is fixed at a position facing reflection panel 70 of main chassis 1. Light 
emitting light receiving element 71 itself emits light to reflection panel 
70 and is provided at a position suitable to receive reflected light which 
is reflected on the surface of the reflection panel 70. Furthermore, light 
emitting light receiving element 71 is connected to frequency/voltage 
converter 72, comparator 73 and tape take-up finish determining device 74 
as shown in FIG. 25. The structure of the tape take-up detecting device is 
same as the conventional structure shown in FIG. 25, so that the 
description thereof is not repeated here. 
It is not limited to the structure in which reflection panel 70 is fixed to 
reverse gear 51, but it may be provided on the same axis as drive axis 10 
so that it can rotates integrally with play gear 37 (the second rotating 
body). In this case, light emitting light receiving element 71 must be 
attached at a position facing to the surface of reflection panel 70 
located coaxially with drive axis 10. 
Next, operation of the above-described magnetic recording/reproducing 
apparatus according to the present invention will be described. 
First, referring to FIG. 1, a standstill state is described. In the 
standstill state, the position of play idler lever 12 is held by head 
plate 16 and the position of FF/REW idler lever 13 is held by FF/REW 
torsion spring 22. Play idler gear 20 and FF/REW idler gear 21 are located 
on a center line between a pair of reel axes 2c and 2d. And furthermore, 
play idler gear 20 and FF/REW idler gear 21 are located so that they 
almost overlap with each other in a plane. The large-diameter gear 20a of 
play idler gear 20 is then being separated from small-diameter gear 37b of 
play gear 37 and the small-diameter gear 51b of reverse gear 51, and the 
small-diameter gear 20b of play idler gear 20 is being separated from the 
large-diameter gear 3a of FOR reel stand 3 and the large-diameter gear 4a 
of REV reel stand 4. Also, the large-diameter gear 21a of FF/REW idler 
gear 21 is being separated from the small-diameter gear 3b of FOR reel 
stand 3 and the small-diameter gear 4b of REV reel stand 4, and the 
small-diameter gear 21b is being separated from FF gear 35 and REW gear 
50. Accordingly, even when pulley 11 receives the rotation power from 
motor 7 and rotates, both of reel stands 3 and 4 do not rotate. 
Next, the forward play mode will be described. This mode corresponds to a 
forward direction reproducing mode and a forward direction recording mode. 
FIG. 7 is a plan structural view showing positional relationship of 
rotation parts in the forward play mode. Referring to FIGS. 5 through 7, 
head plate 16 moves in the direction of the arrow A with operation of the 
first cam from the above-described standstill state, reverse plate 17 
makes play idler lever 12 pivot clockwise about axis 2b to bring the 
small-diameter gear 20b of play idler gear 20 into mesh with the 
large-diameter gear 3a of FOR reel stand 3, and bring the large-diameter 
gear 20a into mesh with the small-diameter gear 37b of play gear 37. When 
those gears are brought into mesh, the press force of reverse plate 17 is 
elastically absorbed by left arm portion 12b having elasticity. 
Similarly, head plate 16 is moved by the first cam in the direction of the 
arrow A, FOR pinch roller spring 14b is then pressed in the direction of 
the arrow A by bend portion 17a of reverse plate 17. FOR pinch roller 
block 14 pivots clockwise about the axis la and the pinch roller 14a 
presses FOR capstan axis 5a to sandwich and hold tape. Then, the tape is 
driven at a constant speed in the direction of the arrow C. Furthermore, 
the bend portion 17b of reverse plate 17 presses left arm portion 12b of 
play idler lever 12. At this time, head plate 16 has somewhat moved in the 
direction of the arrow A and pin 12a of play idler lever 12 has gotten out 
of long hole 16a-1 of guide hole 16a of head plate 16. Accordingly, play 
idler lever 12 is pivotable about axis 2b and pivots clockwise around axis 
2b by reverse plate 17. 
The rotation transmitting path in the forward play mode is shown below. 
Motor 7 (counterclockwise).fwdarw.pulley 7a (counterclockwise).fwdarw.fly 
belt 8.fwdarw.FOR fly wheel 5 counterclockwise).fwdarw.fly pulley 5b 
(counterclockwise).fwdarw.drive belt 9.fwdarw.pulley 11 
(counterclockwise).fwdarw.the first friction mechanism.fwdarw.friction 
plate 31 (counterclockwise) .fwdarw.spring bearing 30 
(counterclockwise).fwdarw.drive axis 10 (counterclockwise).fwdarw.FF gear 
35 (counterclockwise).fwdarw.the second friction mechanism.fwdarw.play 
gear 37 (counterclockwise).fwdarw.play idler gear 20.fwdarw.FOR reel stand 
3 (counterclockwise). 
Accordingly, FOR reel stand 3 runs tape in the forward direction at a 
constant speed with low torque, e.g., 35 g.cm through the second friction 
mechanism. 
Next, the reverse play mode is described. 
This mode corresponds to the reverse direction playback mode and the 
reverse direction recording mode. 
Referring to FIGS. 8 through 10, the second cam is triggered by reverse 
play operation means, and reverse plate 17 is moved in the direction of 
the arrow D via head plate 16 by the second cam. On completion of movement 
of reverse plate 17, the first cam is operated by the trigger means (not 
shown), and head plate 16 moves in the direction of the arrow A to 
implement the reverse play mode. The operation will be described in more 
detail below. When reverse plate 17 has moved in the direction of the 
arrow D, the bend portion 17c of reverse plate 17 faces to the arm of REV 
pinch roller spring 15b of REV pinch roller block 15, and also the bend 
portion 17d faces to right arm 12c of play idler lever 12. Then, when the 
head plate 16 moves in the direction of the arrow A, the bend portion 17c 
of reverse plate 17 presses REV pinch roller spring 15b in the direction 
of the arrow A, and REV pinch roller block 15 pivots counterclockwise 
about axis 1b. Then, pinch roller 15a presses REV capstan axis 6a to 
sandwich and hold tape, which is driven at a constant speed in the 
direction of the arrow D. The head thus applies recording or playback 
operation to the tape. Furthermore, bend portion 17d of reverse plate 17 
presses right arm 12c, formed of elastic material, of play idler lever 12. 
Then, similarly to the mode switching from the above-described standstill 
state to the forward play state, play idler lever 12 is pivotable about 
axis 2b. Accordingly, play idler lever 12 pivots counterclockwise about 
the axis 2b. Thus, small-diameter gear 20b of play idler gear 20 meshes 
with large-diameter gear 4a of REV reel stand 4 and large-diameter gear 
20a meshes with small-diameter gear 51b of reverse gear 51. After those 
gears mesh with each other, the pressing force of reverse plate 17 is 
elastically absorbed by right arm 12c having elasticity. The rotation 
transmitting path in the reverse play mode is shown below. 
Pulley 11 (counterclockwise).fwdarw.first friction 
mechanism.fwdarw.friction panel 31.fwdarw.spring bearing 30.fwdarw.drive 
axis 10.fwdarw.FF gear 35.fwdarw.second friction mechanism.fwdarw.play 
gear 37 (counterclockwise).fwdarw.reverse gear 51 (clockwise).fwdarw.play 
idler gear 20 (counterclockwise).fwdarw.REV reel stand 4 (clockwise). 
Accordingly, REV reel stand 4 runs tape at a constant speed in the opposite 
direction with low torque, e.g., 35 g.cm through the second friction 
mechanism. 
Next, the forward direction fast forwarding mode (FF mode) is described. 
Referring to FIGS. 11 and 13, FF lever 18 is moved in the direction of 
arrow A, FF/REW idler lever 13 then pivots clockwise about axis 2b. Then, 
large-diameter gear 21a of FF/REW idler gear 21 is brought into mesh with 
small-diameter gear 3b of FOR reel stand 3 and small-diameter gear 21b is 
brought into mesh with gear 35a of FF gear 35. After these gears are 
brought into mesh, the pressing force of FF lever 18 is elastically 
absorbed by left arm 13a having elasticity. The rotation transmitting path 
in the FF mode is shown below. 
Pulley 11 (counterclockwise).fwdarw.the first friction 
mechanism.fwdarw.friction panel 31.fwdarw.spring bearing 30.fwdarw.drive 
axis 10.fwdarw.FF gear 35 (counterclockwise).fwdarw.FF/REW idler gear 21 
(clockwise).fwdarw.FOR reel stand 3 (counterclockwise). 
Accordingly, FOR reel stand 3 runs tape in the forward direction at a high 
speed with high torque, e.g., 80 g.cm only through the first friction 
mechanism. In the mode, play idler lever 12 is held at a position of the 
original standstill state. 
Furthermore, the rewinding mode (REW mode) is described. 
Referring to FIGS. 14 through 16, REW 19 is moved in the direction of arrow 
A from the standstill state, FF/REW idler lever 13 then pivots 
counterclockwise about axis 2b. Then, large-diameter gear 21a of FF/REW 
idler gear 21 meshes with small-diameter gear 4b of REV reel stand 4, and 
small-diameter gear 21b meshes with REW gear 50. After these gears have 
been brought into mesh, the pressing force of REW lever 19 is elastically 
absorbed by right arm 13b having elasticity. The rotation transmitting 
path in the REW mode is shown below. 
Pulley 11.fwdarw.the first friction mechanism.fwdarw.friction plate 
31.fwdarw.spring bearing 30.fwdarw.drive axis 10.fwdarw.FF gear 35 
.fwdarw.REW gear 50.fwdarw.FF/REW idler gear 21.fwdarw.REV reel stand 4. 
Accordingly, REV reel stand 4 runs tape in the reverse direction at a high 
speed with high torque, e.g., 80 g.cm only through the first friction 
mechanism. Play idler lever 12 is maintained at a position in the 
standstill state in the REW mode. 
Basic operations of the magnetic recording/reproducing apparatus of the 
present invention have been described above. 
The magnetic recording/reproducing apparatus as described above has the 
following features. 
(1) The structure of drive block 2 is made compact. 
That is to say, the structure of drive block 2 is configured so that it 
satisfies the following three conditions. 
1 Let .theta..sub.1 represent rotation angle from the standstill state to 
the play forward mode of play idler lever 12, let .theta..sub.2 represent 
rotation angle thereof from the standstill state to the play reverse mode, 
let .theta..sub.3 represent rotation angle thereof from the standstill 
state to the FF mode of FF/REW idler lever 13, and let .theta..sub.4 
represent rotation angle thereof from the standstill state to the REW 
mode, then the relation of .theta..sub.1 =.theta..sub.2 
.apprxeq..theta..sub.3 =.sub.4 is satisfied. 
2 Regarding the pivot radius l.sub.1, l.sub.2 of play idler gear 20 and 
FF/REW idler gear 21, the relation of l.sub.1 .apprxeq.l.sub.2 is 
satisfied. 
3 Diameters of play idler gear 20 and FF/REW idler gear 21 are equal to 
each other. 
When the conditions are satisfied, the movable ranges of play idler gear 20 
and FF/REW idler gear 21 can be made equal. Then by the characteristics, 
by providing play idler lever 12 to which play idler gear 20 is attached 
and FF/REW idler lever 13 to which FF/REW idler gear 21 is attached 
overlapping on the same axis, the structure of drive block 2 can be made 
compact. It is possible to make strictly equal movable ranges of play 
idler lever 12 and play idler gear 20, and FF/REW idler lever 13 and 
FF/REW idler gear 21 by appropriately setting a value of the rotation 
transmission ratio from the motor in constant running and high speed 
take-up running of tape. 
(2) A compact automatic reverse mechanism is configured having structure in 
which REV gear 50 and reverse gear 51 are provided on the same axis. 
(3) It is configured so that play idler gear 20 and FF/REW idler gear 21 
receive action force in the toothing direction about gears mutually mesh 
(the direction for strengthening the engagement among play idler gear 20 
and FF/REW idler gear 21, and other gears which engage with them; 
hereinafter referred to as a toothing direction). 
The structure is described below. 
Referring to FIG. 17, small-diameter gear 37b of play gear 37 rotating 
counterclockwise rotates large-diameter gear 20a of play idler gear 20 
clockwise. That is to say, play idler gear 20 is provided with tangential 
force represented by vector A at the contact portion of large-diameter 
gear 20a and small-diameter gear 37b of play gear 37. Now, small-diameter 
gear 20b of play idler gear 20 which clockwise rotates makes 
large-diameter gear 3a of FOR reel stand 3 rotate counterclockwise. That 
is to say, play idler gear 20 works as a driving source for FOR reel stand 
3. Accordingly, FOR reel stand 3 is provided with tangential force in the 
direction opposite to the vector B.sub.1 at a contact portion of 
small-diameter gear 20b of play idler gear 20 and large-diameter gear 3a 
of FOR reel stand 3. Then, play idler gear 20 is provided with reaction 
force of load equal to vector B.sub.1. Accordingly, play idler gear 20 
receives load of the composite vector C.sub.1 of the vector A.sub.1 and 
vector B.sub.1. The composite force effects in the toothing direction for 
play gear 37 and FOR reel stand 3. Accordingly, in the forward play mode, 
play idler gear 20 receives the action force in the toothing direction. 
Referring to FIG. 18, small-diameter gear 51b of reverse gear 51 rotating 
clockwise rotates large-diameter gear 20a of play idler gear 20 
counterclockwise. That is, reverse gear 51 works as a driving source for 
play idler gear 20. Accordingly, play idler gear 20 receives the 
tangential force represented by the vector A.sub.2 at a contact and 
small-diameter gear 51b of reverse gear 51. On the other hand, 
small-diameter gear 20b of play idler gear 20 rotating counterclockwise 
rotates large-diameter gear 4a of REV reel stand 4 clockwise. That is, 
play idler gear 20 works as a driving source for REV reel stand 4. 
Accordingly, REV reel stand 4 receives the tangential force in the 
opposite direction to the vector B.sub.2 at a contact portion of 
large-diameter gear 4a of REV reel stand 4 and small-diameter gear 20b of 
play idler gear 20. Play idler gear 20 then receives reaction force as 
load of the vector B.sub.2. Accordingly, play idler gear 20 receives load 
of the composite vector C.sub.2 of the vector A.sub.2 and the vector 
B.sub.2. The load C.sub.2 works in the toothing direction for reverse gear 
51 and REV reel stand 4. Accordingly, play idler gear 20 receives the 
action force in the toothing direction even in the reverse play mode. 
Referring to FIG. 19, FF gear 35 which rotates counterclockwise rotates 
small-diameter gear 21b of FF/REW idler gear 21 clockwise. That is, FF 
gear 35 works as a driving source for FF/REW idler gear 21. Accordingly, 
FF/REW idler gear 21 receives the tangential force represented by the 
vector A.sub.3 at a contact portion of FF gear 35 and small-diameter gear 
21b of FF/REW idler gear 21. On the other hand, large-diameter gear 21a of 
FF/REW idler gear 21 rotating clockwise rotates small-diameter gear 3b of 
FOR reel stand 3 counterclockwise. That is to say, FF/REW idler gear 21 
works as a driving source for FOR reel stand 3. Accordingly, FOR reel 
stand 3 is provided with the tangential force in the opposite direction to 
the vector B.sub.3 at a contact portion of small-diameter gear 3b of FOR 
reel stand 3 and large-diameter gear 21a of FF/REW idler gear 21. The 
FF/REW idler gear 21 receives the reaction force as load of the vector 
B.sub.3. Accordingly, FF/REW idler gear 21 receives load of the composite 
vector C.sub.3 of the vector A.sub.3 and the vector B.sub.3. The working 
direction of the composite force C.sub.3 is the toothing direction to FF 
gear 35 and FOR reel stand 3. Accordingly, FF/REW idler gear 21 receives 
the action force in the toothing direction also in the FF mode. 
Referring to FIG. 20, REW gear 50 rotating clockwise rotates small-diameter 
gear 21b of FF/REW idler gear 21 counterclockwise. That is, REW gear 50 
works as a driving source for FF/REW idler gear 21. Accordingly, FF/REW 
idler gear 21 receives the tangential force of the vector A.sub.4 at a 
contact portion of small-diameter gear 21b of FF/REW idler gear 21 and REW 
gear 50. On the other hand, large-diameter gear 21a of FF/REW idler gear 
21 rotating counterclockwise rotates small-diameter gear 4b of REV reel 
stand 4 clockwise. That is to say, FF/REW idler gear works as a driving 
source for REV reel stand 4. Accordingly, REV reel stand 4 receives the 
tangential force in the opposite direction to the vector B.sub.4 at the 
contact portion of small-diameter gear 4b of REV reel stand 4 and 
large-diameter gear 21a of FF/REW idler gear 21. The FF/REW idler gear 21 
receives the reaction force as load of the vector B.sub.4. Accordingly, 
FF/REW idler gear 21 receives load of the composite vector C.sub.4 of the 
vector A.sub.4 and the vector B.sub.4. The working direction of the 
composite force C.sub.4 is the toothing direction of REW gear 50 and REV 
reel stand 4. Accordingly, FF/REW idler lever 21 receives the action force 
in the toothing direction. 
As described above, in any operation modes, play idler gear 20 and FF/REW 
idler gear 21 receive the action force in the toothing direction. 
In the above description, the more important point is that vector loads 
A.sub.1 -A.sub.4, B.sub.1 -B.sub.4 respectively working on play idler gear 
20 and FF/REW idler gear 21 all work to pivot play idler lever 12 and 
FF/REW idler lever 13 in the toothing direction. In such conditions, when 
transmitting rotation force between first rotating bodies which are 
driving sources and rotating bodies which are terminal objects of the 
transmission with pivot rotation transmitting bodies interposed 
therebetween, engagement is surely implemented without any connection with 
which of the first rotating bodies and the terminal transmission target 
bodies are brought into mesh with pivot rotation transmission bodies. 
Accordingly, such structure is excellent in that the flexibility in 
designing arrangement of these rotating bodies is enhanced. The structure 
in which action force works on pivot rotate transmission bodies in the 
toothing direction enables to compensate for the errors of pivoting stroke 
of pivot rotate transmission bodies with the action force working in the 
toothing direction. Therefore, the flexibility in arrangement designing of 
a rotation system is enhanced accordingly. 
The following conditions should be satisfied to make play idler gear 20 and 
FF/REW idler gear 21 receive the action force in the toothing direction in 
all the modes as described above. 
1 Play gear 37 and reverse gear 51 are located on the arrow A side than a 
line connecting rotation centers of FOR reel stand 3 and REV reel stand 4, 
and also they are provided at positions symmetrical about the 
perpendicular bisector of a line connecting rotation centers of FOR reel 
stand 3 and REV reel stand 4. 
2 FF gear 35 and play gear 37 provided on the same axis and REW gear 50 and 
reverse gear 51 further provided on the same axis are arranged symmetrical 
about the perpendicular bisector of the line connecting rotation centers 
of the two reel stands 3 and 4. 
3 The pivot center 2b of play idler lever 12 and FF/REW idler lever 13 is 
located on the arrow B side than the line connecting rotation centers of 
play gear 37 and reverse gear 51 and also located on the perpendicular 
bisector of the segment connecting rotation centers of the two reel stands 
3 and 4. 
Although an example in which the first and second friction mechanisms are 
provided in friction block 60 has been described in the above embodiments, 
a third friction mechanism may be further provided between REW gear 50 and 
reverse gear 51. Providing the third friction mechanism enables to provide 
torque generating means only for use in the reverse play. For example, it 
is enabled to make torque differ in the forward play mode and in the 
reverse play mode, and the transmission loss of reverse gear 51 interposed 
between play gear 37 and REV reel stand 4 does not have to be considered. 
Although means for reciprocating head plate 16 on which a head is provided 
is shown for pivoting play idler lever 12 in the above embodiment, a 
method using an overstroke lever may be introduced. This is useful in a 
magnetic recording/reproducing apparatus having sound interval detecting 
mechanism. The overstroke lever has such structure as described below. In 
a tape recorder, it is extremely important to keep the contact relation 
appropriate between tape and a head in playback and recording. 
Accordingly, it is an important problem to which extent the head moves in 
the tape contact direction when playing back. The quantity of movement of 
the head is referred to as a head stroke. In the above embodiment, the 
head plate 16 moves in the direction of the arrow A when reproducing with 
operation of the first cam. However, in such structure, the quantity of 
movement of head plate 16 slightly varies due to variation in parts 
accuracy. Therefore, an abut portion is provided on main chassis 1, and 
when the head plate 16 abuts against it, the movement of head plate 16 is 
limited so that the abutting state is of the most appropriate head stroke. 
However, only with operation of the first cam, the head stroke varies due 
to variation in parts and the like. Accordingly, an overstroke lever is 
necessary. That is, head plate 16 is moved by a stroke larger than a 
predetermined necessary stroke to move the overstroke lever. A tension 
spring is provided between the overstroke lever and the head plate. When 
the overstroke lever moves in the direction of arrow A, the head plate 16 
is moved in the direction of the arrow A through the tension spring. When 
the head plate 16 abuts against the abut portion of main chassis 1, the 
head plate 16 does not move in the direction of the arrow A further more. 
The overstroke lever only moves in the direction of the arrow A. Then, the 
tension spring extends therebetween to absorb the overstroke. 
When detecting sound intervals, the head position is moved slightly 
backwards in a range capable of having contact with tape, because abrasion 
of the head is considerable with the head stroke for reproducing, or 
because torque larger than the torque for normal high speed run is 
required due to the pad pressure on the tape side, for example. The amount 
of backward movement from the reproducing state to the sound interval 
detecting state is usually about 1.5-2.0 mm. If there is no overstroke, 
the engagement of play idler gear 20 and, FOR reel stand 3 or REV reel 
stand 4 has to be released only with the backward movement of about 
1.5-2.0 mm. However, if reverse plate 17 is provided above the overstroke 
lever, the amount of movement of the overstroke lever from the reproducing 
state to the sound interval detecting state is a value obtained by adding 
the overstroke quantity, for example 1.0 mm, to the amount of backward 
movement of the head plate of about 1.5-2.0 mm. Accordingly, it is about 
2.5-3.0 mm, so that the toothing between play idler gear 20 and FOR reel 
stand 3 or REV reel stand 4 can be canceled having a margin. 
Next, operation of the tape take-up detecting mechanism will be described. 
First, in the forward play mode, the rotation transmitting path is 
configured as follows as described before. 
Motor 7 (counterclockwise).fwdarw.pulley 7a (counterclockwise).fwdarw.fly 
belt 8.fwdarw.FOR fly wheel 5 (counterclockwise).fwdarw.fly pulley 5b 
(counterclockwise) drive belt 9.fwdarw.pulley 11 
(counterclockwise).fwdarw.first friction mechanism.fwdarw.friction plate 
31 (counterclockwise) .fwdarw.spring bearing 30 
(counterclockwise).fwdarw.drive axis 10 (counterclockwise).fwdarw.FF gear 
35 (counterclockwise) second second friction mechanism.fwdarw.play gear 37 
(counterclockwise).fwdarw.play idler gear 20.fwdarw.FOR reel stand 3 
(counterclockwise). 
Separately from the transmission path, large-diameter gear 37a of play gear 
37 and large-diameter gear 51a of reverse gear 51 engage with each other. 
Accordingly, in the forward play condition, reverse gear 51 also rotates 
receiving the rotating force of play gear 37. Accordingly, reflection 
panel 70 fixed to reverse gear 51 also rotates integrally with reverse 
gear 51. Accordingly, light emitting light receiving element 71 receives 
reflected light from rotating reflection panel 70, accepts the periodical 
signal, detects rotation conditions of reverse gear 51 with electrical 
determining means, and thereby detects that cassette tape is being taken 
up. 
In the forward play mode as described above, when cassette magnetic tape 
has been taken up by a reel on FOR reel stand 3, the rotation of FOR reel 
stand 3 is stopped with the tension of tape. When the rotation of FOR reel 
stand 3 is interrupted, rotation of play idler gear 20 and play gear 37 is 
stopped. The rotation of reverse gear 51 which has been rotating engaging 
with large-diameter gear 37a of play gear 37 is thus stopped and the 
rotation of reflection panel 70 fixed to reverse gear 51 is also stopped. 
Accordingly, the rotation stop operation of reflection panel 70 is 
detected by an electrical detecting means through light emitting light 
receiving element 71, and a determination is made that the tape has been 
already taken up. Thus, an automatic stop mechanism operates to stop 
operation of the driving device. 
With such detection of rotation stopping operation, if FOR reel stand 3 
stops because of abnormal cause, for example, the automatic stop mechanism 
operates because a determination is made that the tape has been taken up 
even in the course of taking up cassette tape, to stop drive of the tape. 
Next, the reverse play mode is described. The transmission path of rotation 
force in the reverse play mode is shown below. 
Pulley 11.fwdarw.the first friction mechanism.fwdarw.friction plate 
31.fwdarw.spring bearing 30.fwdarw.drive axis 10.fwdarw.FF gear 35 
.fwdarw.the second friction mechanism.fwdarw.play gear 37.fwdarw.reverse 
gear 51.fwdarw.play idler gear 20.fwdarw.REV reel stand 4. 
In this mode, reverse gear 51 rotates and the reflection panel 70 fixed to 
the reverse gear 51 is also integrally rotating. 
When the magnetic tape of cassette tape has been taken up by the reel on 
the REV reel stand 4 side, the rotation of REV reel stand is interrupted 
by the tension of the tape. When the rotation of REV reel stand 4 stops, 
rotations of play idler gear 20, reverse gear 51 and play gear 37 are 
stopped, respectively. Accordingly, the rotation of reflection panel 70 
fixed to reverse gear 51 also stops. A determination is thus made that the 
tape has been taken up, and the automatic stop mechanism operates to stop 
drive of the tape. 
If the rotation of REV reel stand 4 is stopped in the course of taking up 
operation of tape due to some reason in this mode, the automatic stop 
mechanism works with operation similar to the above described one to 
smoothly terminate driven condition of tape. 
Next, operation in the forward direction fast forward mode (FF mode) will 
be described. The transmission path of the rotation force in the FF mode 
is shown below. 
Pulley 11.fwdarw.the first friction mechanism.fwdarw.friction panel 
31.fwdarw.spring bearing 30.fwdarw.drive axis 10.fwdarw.FF gear 35 
.fwdarw.FF/REW idler gear 21.fwdarw.FOR reel stand 3. 
Furthermore, separately from the rotation transmission path, FF gear 35, 
the second friction mechanism, play gear 37, and reverse gear 51 are in 
rotating states independently of the drive system. Since reverse gear 51 
rotates, reflection panel 70 also rotates. 
When the tape has been taken up in this mode, the rotation of FOR reel 
stand 3 is interrupted by the tension of tape. When the rotation of FOR 
reel stand 3 stops, the rotation of FF/REW idler gear 21, FF gear 35, play 
gear 37 and reverse gear 51 is stopped. Accordingly, the tape take-up 
finish state is detected with stop of the rotation of reflection panel 70 
which is integral with reverse gear 51 and the automatic stop mechanism 
operates to stop drive of cassette tape. 
Furthermore, the rewinding mode (REW mode) is described. The transmission 
path of the rotation force of REW mode is shown below. 
Pulley 11.fwdarw.the first friction mechanism.fwdarw.friction plate 
31.fwdarw.spring bearing 30.fwdarw.drive axis 10.fwdarw.FF gear 35 
.fwdarw.REW gear 50.fwdarw.FF/REW idler gear 21.fwdarw.REV reel stand 4. 
Separately from the rotation force transmission path, FF gear 35, the 
second friction mechanism, play gear 37 and reverse gear 51 engage with 
each other and receive the rotation force to rotate. Reflection panel 70 
is rotating integrally with reverse gear 51. 
When the tape has been taken up in the REW mode, REW reel stand 4 is 
prevented from rotating by the tension of tape. On stop of rotation of REV 
reel stand 4, the rotation of FF/REW idler gear 21, REW gear 50 and FF 
gear 35 is stopped. Furthermore, play gear 37 and reverse gear 51 of the 
second friction mechanism linked to FF gear 35 is also stopped. 
Accordingly, with stop of rotation of rotation panel 70 fixed to reverse 
gear 51, the tape take-up finish condition is determined, and the 
automatic stop mechanism operates to stop drive of tape. 
As described above, in all the modes of constant speed, high speed running 
modes in the forward direction and the reverse direction, the take-up, and 
the take-up finish states of cassette tape can be detected. When a 
determination is made that the taking-up of the tape has finished, the 
automatic stop mechanism works to smoothly stop drive of the tape. 
As described above, the magnetic recording/reproducing apparatus according 
to the present invention includes the first rotating body generating high 
torque through the first friction transmission means, and the second 
rotating body generating low torque through the second friction 
transmission means, which are provided independently of each other, 
wherein control of torque respectively required is facilitated to enable 
stable tape running operation in any of high speed running of tape 
requiring high torque and constant speed running requiring low torque. 
Also, since the first rotating body and the second rotating body 
generating predetermined torque are independent of each other, the 
structure of rotation transmitting means transmitting the predetermined 
torque generated by the two is simplified to enhance transmission 
efficiency. 
Furthermore, by providing the third rotating body, fourth rotating body, 
and the first and second swinging members on the same axis as rotation 
transmitting means, the space in the structure can be saved. 
Furthermore, making pivot ranges of rotation force transmitting means for 
the forward direction running of the tape and rotation force transmitting 
means for the reverse direction running substantially same, the structure 
can be made compact. 
Furthermore, by providing the fifth rotating body and the sixth rotating 
body which always stays in mesh with the first rotating body and the 
second rotating body provided on the same axis, and also are located on 
the same axis, the so-called automatic reverse mechanism can be 
implemented. 
Furthermore, with reel means, forward direction torque generating means, 
reverse direction torque generating means and rotation force transmitting 
means provided with predetermined positional relationship on a substrate, 
it is configured so that rotation bodies of rotation force transmitting 
means receive action force in the toothing direction for the driving 
source and the transmitted rotation body, which enables smooth 
transmission of rotation force and enhances reliability and transmission 
efficiency of rotation operation. 
Furthermore, in the magnetic recording/reproducing apparatus according to 
the present invention, with a rotation detecting body provided on either 
of second or sixth rotation body which gangs with rotation operation of 
the first and second reels in constant speed run in the forward direction 
and the reverse direction, the tape take-up conditions can be determined 
without any connection with the direction of tape running, which enables 
sure automatic stopping operation in all operation conditions to prevent 
damage of the cassette tape and the like when the tape stops with abnormal 
conditions. 
Although the present invention has been described and illustrated in 
detail, it is clearly understood that the same is by way of illustration 
and example only and is not to be taken by way of limitation, the spirit 
and scope of the present invention being limited only by the terms of the 
appended claims.