GB2164710A - One-way clutch mechanism for small-size tape recorder - Google Patents

Abstract

Pulley 78 carries a pivotable member 176 having a pin 178 engaging a guide surface 164a in a cam plate 164 so that rotation of the pulley in one direction causes the pin 178 to engage a tooth 162a on a ratchet cam 162, whereas rotation of the pulley in the opposite direction moves the pin along the guide surface so that the pulley and a shaft 160 become disengaged. Thus, when the clutch is provided in the drive to a tape recorder reel, the clutch is positively disengaged when the reel is serving as a tape supply reel, and accidental engagement of the clutch, which would cause stretching of the tape, is prevented. <IMAGE>

Description

SPECIFICATION One-way clutch mechanism for small-size tape recorder BACKGROUND OF THE INVENTION The present invention relates to a small-size tape recorder and, more particularly, to a one-way clutch mechanism suitable for driving a reel hub shaft of a small-size tape recorder.

In modern offices, for example, a small-size tape recorder which is generally referred to as a dictator/transcriber is extensively used. With such a tape recorder, one is allowed to typewrite messages previously recorded in the tape recorder while reproducing and listening to them. A tape recorder of the kind described is available as a desk-top type which is fixely set on a desk or a portable type which may be carried by a person. The desk-top type tape recorder generally uses an ordinary audio tape cassette, while the portable type tape recorder generally uses a miniature tape cassette, or microcassette, which is dimensioned about 1/4 the audio cassette tape. Usually, after messages recorded in a dictator/transcriber have been fully reproduced, all of them are erased for secrecy.

As well known in the art, a pair of reel hub shafts installed in a tape recorder which uses a microcassette are each furnished with a one-way clutch so as to be rotatable in the opposite directions to each other (see Japanese Patent Publication No. 59-36341, for example). A prior art one-way clutch for such an application is simply implemented by a ratchet cam and a ratchet.

When a tape cassette is loaded in the tape recorder and then a tape encased in the cassette is driven in a fast forward (FF) mode or a rewind (Rew) mode, a one-way clutch on a take-up side is activated, or coupled, and a one-way clutch on a supply side is deactivated, or uncoupled.

After more than one half of the tape length has been taken up by a take-up reel, the tape diameter on a supply reel becomes smaller than that on the take-up reel with the result that the supply reel is driven faster than the take-up reel.

Such fast rotation of the supply reel causes the one-way clutch associated therewith and uncoupled to become unstable, often bringing the ratchet into unexpected engagement with the ratchet cam. This applies undesired back tension to the tape recorder in addition to the back tension which is customarily applied. The additional back tension not only increases the load which acts on the reel hub shaft associated with the take-up reel but also extraordinarily stretches and, thereby, damages the tape being transported.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a one-way clutch mechanism which eliminates an increase in the load which should be born by a reel hub shaft on the takeup side during a faste feed mode operation or a rewind mode operation of a tape recorder.

It is another object of the present invention to provide a one-way clutch mechanism which enhances durability of a tape recorder and frees a magnetic tape from damage.

It is another object of the present invention to provide a generally improved one-way clutch for a small-size tape recorder.

A one-way clutch mechanism for rotating a rotary shaft which is rotatably supported by a base member of a device in which the mechanism is installed of the present invention comprises a bearing mounted on the base member for rotatably supporting the rotary shaft, a ratchet cam provided with a plurality of engaging portions along a circumference and mounted on the rotary member, a rotary member rotatably supported by the bearing, a cam plate rotatably supported by the bearing and provided with a guide portion, the cam plate being frictionally engage with and rotatable relative to the rotary member, and a rotatable locking member pivotted at one end to the rotary member and configured at the other end to selectively lock the engaging portion of the ratchet cam, the locking member being guided by and retained by the guide portion of the cam plate.When the rotary member is driven to rotate in one direction, the locking member is rotated along the guide portion of the cam plate to release the rotary shaft and the rotary member from each other.

In accordance with the present invention, a one-way clutch is disclosed in which when a rotary member is rotated in an inoperative direction of the clutch, a locking member provided on the drive rotary member which is engageable with a rotary shaft surely cancels the engagement of the rotary member and the driven rotary shaft.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a front view of a small-size tape recorder to which the present invention is applicable; Figure 1B is a fragmentary side elevation of the tape recorder of Fig. 1A; Figure 1C is a perspective view of the tape recorder of Fig. 1A as viewed from the back, a lid for cassette insertion being shown in an open position; Figure 2A is a perspective view of a miniature tape cassette, or microcassette, applicable to the tape recorder shown in Figs. 1A-1C; Figure 2B shows the tape cassette of Fig. 2A in a plan view with an upper cassette half removed; Figure 3 is a plan view of mechanical arrangements installed in the tape recorder in which oneway clutch mechanisms in accordance with the present invention are built in; Figure 4 is a plan view of a drive system of a cassette reel drive section;; Figure 5 is a plan view of a slide base drive mechanism; Figure 6 is an enlarged section of the one-way clutch mechanism with is associated with a reel hub shaft on a supply side; Figure 7 is a view similar to Fig. 6 but showing the one-way clutch mechanism which is associated with a reel hub shaft on a take-up side; Figure 8 shows any of the one-way clutch mechanisms which is in operation; Figure 9 is an exploded perspective view showing a relationship between a cam switch mechanism and a mounting shaft; Figure 10 shows printed patterns on a printed circuit board which is included in the cam switch mechanism; Figure 11 is a block diagram showing an electrical arrangement of a slide base position control mechanism; Figure 12 shows a relationship between the printed patterns and various mode positions of a slide base;; Figure 13 is a plot showing a relationship between rotation angles of a cam and positions of the slide base; and Figure 14 is a timing chart representative of timings for instructing various operation modes.

DESCRIPTION OF THE PREFERRED EMBODIMENT While the one-way clutch mechanism for a small-size tape recorder of the present invention is susceptible of numerous physical embodiments, depending upon the environment and requirements of use, a substantial number of the herein shown and described embodiment have been made, tested and used, and all have performed in an eminently satisfactory manner.

Referring to Figs. 1A-1C, a tape recorder TR comprises a casing 10 and a lid 12 having a generally U-shaped section and defining a part of the back of the tape recorder TR. As shown in Fig. 1C, a small-size tape cassette TC is loaded in the tape recorder TR as indicated by an arrow P in a horizontal position after opening the lid 12 upwardly over an angle of substantially 90 degrees. As shown in Figs. 1A and 1B, in an upper portion of an upper face (control face) 14 of the casing 10, there are provided a display 16 for displaying a message number 16a assigned to any of recorded messages and a tape count 16b, and a group of mode control buttons 18 located below the display 16. The control button group 18 includes a record (Record) button, a rewind/play (Rew/Play) button and a stop (Stop) button.

The mode control button group 18 is arranged, for example, in a pair of vertically spaced arrays 18a and 18b. Positioned at the center of the respective arrays are the Record button 20 and the Rew/Play button 22 which are the major control buttons. A power (On) button 24 which is another major control button is positioned below the Rew/Play button 22. As shown in Fig. 1A, the major buttons 20 and 22 are sized larger than the others. As seen in Fig. 1B, the two control button arrays 18a and 18b define a trough-like space therebetween. Specifically, the tops of the buttons in each of the arrays 18a and 18b are inclined downwardly toward those of the buttons in the other array.Such a configuration of the mode control button group 18 will allow one to set up desired one of a record mode and a playback mode, which are the predominant modes, without the need for constantly looking at the buttons, thereby enhancing easy'and convenient use of the tape recorder TR as a dictator/transcriber.

As shown in Fig. 1C, a flat, cassette presser member 26 is fixed to the inner surface of the lid 12 and comprises a pair of resilient arms 26a and 26b which extend out toward the tape cassette TC. When the lid 12 is closed, the arms 26a and 26b press the tape cassette TC from above to restrict its position inside the tape recorder TR in the up-down direction. A pair of flat locking members 28 and 30 respectively are fixed to side walls 12a and 12b of the lid 12 and provided with notches 28a and 30a adjacent to the open end of the lid 12. In a record or playback mode in which the lid 12 is closed, the locking members 28 and 30 are latched by locking arms 132 and 134, which will appear, to prevent the lid 12 from being opened. As later described in detail, the locking arms 132 and 134 cooperate with a slide base 106 (Fig. 3) which is installed in the tape casing 10.

Referring to Figs. 2A and 2B, the tape cassette TC comprises a casing 32 which is made up of an upper half 34 and a lower half 36. The upper and lower cassette halves 34 and 36 are rigidly connected together at their engaging portions 34a and 36a. The cassette TC has flat and rectangular upper and lower surfaces and is open at one of its four sides. Such a configuration of the cassette TC is substantially similar to that of ordinary tape cassettes. The cassette TC has a length a of about 35 millimeters, a width b of about 25 millimeters, and a thickness c of about 4 millimeters, which are substantially 1/3 the dimensions of currently marketed microcassettes. The open side of the cassette TC, labeled 38, includes inlets 44 and 46 which respectively are substantially aligned with a pair of reels 40 and 42 positioned inside the cassette TC.

Each of the inlets 44 and 46 allows a magnetic head 108, which will be described, to enter the cassette TC therethrough. Two pairs of upper and lower thinned portions 44a and 44b are provided at both sides of the inlet 44, while two pairs of upper and lower thinned portions 46a and 46b are provided at both sides of the inlet 46. These thinned portions 44a, 44b, 46a and 46b are adapted to accommodate tape guides 120 which are associated with the head 108. An inwardly tapered notch 48 extends vertically in a part of the cassette open side 38 which is substantially intermediate between the inlets 44 and 46. The notch 48 is adapted to accommodate a pinch roller 110 which will be described. A pair of openings 50 and 52 are positioned adjacent to the notch 48 so that a capstan 96, which will be described, may extend therethrough.

A pair of tape pads 54 and 56 are resiliently supported by a leaf spring 58 so as to constantly urge a magnetic tape 60 from behind in the inlets 44 and 46, respectively. The tape 60 is wound on the reels 40 and 42 and transported by way of the cassette open side 38 while being guided by guide poles 62 and 64 and guide rollers 66 and 68. Further, a pair notches 32a and 32b are provided at opposite ends of the cassette open side 38 in order to position the cassette TC when the latter is loaded in the tape recorder TR.

Referring to Fig. 3, the mechanical arrangement of the tape recorder TR generally comprises a reel drive section A, a slide base section B in which the head 108, pinch roler 110 and others are mounted, and a slide base drive mechanism C for driving the slide base section B. These sections A, B and C are carried on a chassis base 70. The reel drive section A includes a pair of reel hub shafts 72 and 74 to which supply and take-up functions respectively are assigned as the case may be, and a reel hub drive mechanism 76. The reel hub shafts 72 and 74 are each rotatable in forward and reverse directions driven by a pair of pulleys 78 and 80, which are located in a lower porton of the chassis base 70.As shown in detail in Fig. 4, the reel hub drive mechanism 76 includes a pulley 82 which is provided with a flywheel 82a, a reversible motor (first drive source) 84 for driving the pulley 82, and a first-stage pulley 88 which is driven by the pulley 82 through a belt 86. The rotation of the pulley 88 is transmitted to a secondstage pulley 94 which carries the capstan 96 therewith and bifunctions as a flywheel, by way of a pulley 90 which is integral with the pulley 88 and a belt 92. As shown, the pulley 94 is larger in diameter than the pulley 90. A belt 100 is passed over a pully 98 which is integral with the pulley 94 and the pulleys 78 and 80 which respectively are associated with the reel hub shafts 72 and 74, so that the pulleys 78 and 80 are simultaneously driven at a reduced speed.

As shown in Fig. 3, the slide base section B generally comprises a generally T-shaped slide base 106 defined by a projection 104 which protrudes from a base portion 102, and the head 108 and pinch roller 110 which are mounted on the slide base 106. The base portion 102 of the slide base 106 is provided with slots 102a and 102b at opposite end portions thereof, while the projection 104 is provided with a lengthwise slot 104a. Pins 112 nd 114 extending from the chassis base 70 are received in the slots 102a and 102b, respectively. A pin 116 also extending from the chassis base 70 is received in the slot 104a. In this construction, the slide base 106 is selectively slidable as indicated by arrows X1 and X2 guided and restricted by the pins 112, 114 and 116.The head 108 which is rigid on the slide base 106 includes a fixing portion 108a which is resiliently supported by a coil spring 118 for azimuth adjustment. The tape guides 120 each being generally U-shaped are provided at both sides of the head 108 so that they may enter the guide portions 44a, 44b, 46a and 46b of the cassette TC to restrict the position of the tape 60 in the up-down direction.

An arm 124 is rotatably supported at one end by a shaft 122 which extends from the slide base 106. The pinch roller 110 is rotatably supported by the other end of the arm 124. A coil spring 126 is wound around the shaft 122 in an a configuration and anchored at one end to the side base 106 and at the other end to a locking portion 124a of the arm 124. While the coil spring 126 constantly urges the pinch roller 110 clockwise toward the capstan 96, a pin (not shown) which extends downwardly from the arm 124 abuts against one end of the slide base 106 to restrict the angular movement of the pinch roller 110. A pair of coil springs 128 and 130 are stretched between opposite end portions of the slide base 106 and the chassis base 70 to constantly bias the slide base 106 in the Xr direction (Play direction).When the slide base drive mechanism C is driven forwardly as will be described, the springs 128 and 130 pull the slide base 106 toward the cassette TC in correspondence with an angular position of a cam which is included in a cam switch mechanism.

A pair of locking members 132 and 134 are disposed in a cassette loading portion 70a of the chassis base 70 adjacent to the slide base 106. The locking members 132 and 134 respectively are pivotally mounted on shafts 136 and 138 and engageable at one end portion with one side of the slide base 106 and movable at the other end into and out of side walls 70b and 70c of the chassis base 70 adjacent thereto. While each of the locking members 132 and 134 is biased by a coil spring or like resilient means such that the above-mentioned other end thereof moves toward the inside of the associated side wall 70b or 70c, the angular movement is limited because one side of the locking member is engaged by the side wall 70b or 70c.In this construction, when the slide base 106 is moved in the X1 direction in a record or playback mode operation, its one edge abuts against one end of the locking members 132 and 134 to rotate them outwardly about the shafts 136 and 138. As a result, the locking members 132 and 134 move respectively into the notches 28a and 30a of the lid 12 (Fig. 1C) to prevent the lid 12 from being opened. As the lid 12 is closed after a recording or playback operation which has been performed with the lid 12 open, one side of the locking portions 28 and 30 of the lid 12 abut against the locking members 132 and 134 to rotate them further outwardly against the forces of the coil springs; when the lid 12 has been fully closed, the locking members 132 and 134 are received in their associated notches 28a and 30a to surely lock the lid 12.Designated by the reference numeral 140 in Fig. 3 is a switch section adapted to actuate an amplifier of the tape recorder TR responsive to the movement of the slide base 106.

Referring also to Fig. 5, the slide base drive section C is located at the rear of the slide base 106 and includes a motor (second drive source) 142 for controlling the position of the slide base 106. An output gear 144 is rigidly mounted on an output shaft of the motor 142. The rotation of the gear 144 is transmitted to an intermediate gear 146 which in turn rotates a gear 148 which is integral therewith. The rotation of the gear 148 is transmitted to a gear 150 which is provided with a worm gear 152. A worm wheel 154 is constantly meshed with the worm gear 152 to be driven at a reduced speed. As later described, a cam switch unit (cam switch mechanism) is removably mounted on a shaft 156 which supports the worm wheel 154.

A one-way clutch mechanism in accordance with the present invention will hereinafter be described together with specific constructions and operations of various sections of a tape recorder in which the clutch mechanism is arranged.

(I) One-Way Clutch Mechanism Referring to Figs. 6-8, a one-way clutch mechanism CL, intervenes between the reel hub shaft 72 and the drive pulley 78 and a one-way clutch mechanism CL2 between the reel hub shaft 74 and the drive pulley 80. The clutch mechanisms CLI and CL2 are constructed and arranged to rotate in opposite directions to each other. Specifically, during a forward (Play) rotation which transports the tape 60 in a direction Q, as shown in Figs. 3, 2A and 2B, the clutch CL2 associated with the reel hub shaft 74 is activated, or coupled, while during a reverse (Rew) rotation which transports the tape 58 in a direction Q2 the other clutch CL, is activated.As shown in Fig. 6, the clutch CLI associated with the reel hub shaft 72 which serves as a supply shaft includes a shaft 160 which is rotatably supported by a sleeve 158 which in turn is fixed to the chassis base 70. The shaft 160 carries the reel hub shaft 72 above the sleeve 158 and a ratchet cam 162 and a cam plate 164 below the sleeve 158. The ratchet cam 162 and cam plate 164 are shaped as shown in a rear end view in Fig. 8.

A coil spring 168 is loaded between the sleeve 158 and the reel hub shaft 72 through a support plate 166 which is rigidly mounted on the shaft 160. The pulley 78 is rotatably mounted on a boss 158a of the sleeve 158. The cam plate 164 is also rotatably mounted on the sleeve 158 through a hub 170 which is rigidly mounted on the boss 158a. A coil spring 172 is loaded between the cam plate 164 and the boss 158a in order to constantly bias the cam plate 164 into frictional contact with one face of the pulley 78.

A relationship between the pulley 78, ratchet cam 162 and cam plate 164 which constitute an essential part of the clutch CL, will be described with reference also made to Fig. 8. A pin 174 extends downwardly from the underside of the pulley 78, while a ratchet 176 is pivotally supported by the pin 174 to be engageable with a plurality of engaging portions 162a which are provided on the ratchet cam 162. A cam pin 178 studded on the ratchet 176 is received in and guided by an arcuate recess 164a of the cam plate 164 which extends radially inwardly from the outer periphery of the cam plate 164. When the pulley 78 is driven clockwise as indicated by an arrow, the cam pin 178 is guided by the recess 164a of the cam plate 164 to in turn cause the ratchet 176 to rotate clockwise (toward the center) with respect to the shaft 174 as indicated by a phantom line. As a result, the ratchet 176 is brought into engagement with one of the engaging portions 162a of the ratched cam 162 to drive the ratchet cam 162 and, thereby, the reel hub 72 in a rotational motion. In a Play mode operation in which the pulley 78 rotates counterclockwise, the cam pin 178 on the pulley 78 is forced radially outwardly along the recess 164a as indicated by a solid line with the result that the ratchet 176 is moved counterclockwise with respect to the pin 174 to release the ratchet 176 from the ratchet cam 162. This cuts off the path of rotation transmission to the reel hub shaft 72.

As shown in Fig. 7, the one-way clutch mechanism CL2 which is substantially identical in construction with the clutch mechanism CL, is arranged on the reel hub shaft 74 together with a known friction clutch CL. The reel hub shaft 74 serves as a take-up shaft. Since the clutch mechanism CL2 operates in the opposite direction to the clutch mechanism CL1, its ratchet cam, cam plate and ratchet are movable in the opposite manner to those shown in Fig. 8. Therefore, in Fig. 7, the same structural elements as those shown in Fig. 6 are designated by like reference numerals and will not be described in detail. In Fig. 7, the friction clutch CL having a known construction is interposed between a support plate 166 on a sleeve 158 and the reel hub shaft 74 in order to control the take-up torque.

Specifically, the friction clutch CL includes an auxiliary plate 182 rigidly mounted on the support plate 166, and a friction plate 180 connected to the auxiliary plate 182 by adhesion. A coil spring 184 is compressed between the reel hub shaft 74 and a plate 186 which is retained by the shaft 74. The plate 186 is, therefore, held in frictional contact with one face of the friction plate 180. While the tape 60 paid out by the capstan 96 and pinch roller 110 in the Ql direction is taken up on a take-up reel, the clutch CL having the above construction serves to maintain the tape tension constant by controlling the torque of the pulley 80 and, thereby, safeguards the tape 60 against damage.

Now, assume that the drive pulley 78 and the reel hub 72 are operatively interconnected by a one-way clutch having a known simple construction. Such a clutch reasonably operates in a Play mode operation in which the pulley 78 rotates faster than the ratched cam 162 (driven member).

However, during a fast forward (FF) mode operation or a rewind (Rew) mode operation, after more than one half of the tape length has been wound on the take-up reel, the tape diameter on the supply reel becomes smaller than that on the take-up reel so that the supply reel is caused to rotate faster than the take-up reel. Such fast rotation of the supply reel allows the ratchet cam 162 and the cam pin 178 to undesirably engaged, or bite, each other. In this condition, a back tension is added to that which is ordinarily applied to a supply reel, thereby damaging the tape 60.

Specifically, assuming that the additional back tension is TG, the following relationship holds:

where T is a drive torque, RD is a tape radius on the take-up reel, Rs is a tape radius on the supply reel, r is a reel hub diameter, t is a tape thickness, and L is a tape length (overall length).

The cam plate 164 included in each of the one-way clutch mechanisms CL, and CL2 fulfills the role of suppressing the undesirable back tension T,.

As previously described, the cam plate 164 is constantly urged by the coil spring 172 to remain in frictional contact with the pulley 78 and, hence, it always begins to rotate delayed a moment relative to the pulley 80. Specifically, as the pulley 78 on the drive side is rotated clockwise as viewed in Figs. 2A and 2B, the pin 178 on the ratchet 176 after moving along the recess 164a of the cam plate 164 abuts against the end of the recess 164a and, thereby, entrains the cam plate 164 after a certain time of delay. At the same timing, in the clutch CL2 associated with the pulley 80 on the driven side, the cam pin 174 is forced radially outwardly along the recess 164a and the ratchet 176 is released from the ratchet cam 162.Thereafter, the ratchet 176 associated with the drive pulley 78 locks the engaging portion 162a of the ratchet cam 162 to cause the reel hub shaft 72 to rotate. In this manner, whenever one of the clutches CL, and CL2 is rotated, the other is positively held inoperative, or uncoupled, preventing the undesirable back tension from being applied to the tape 60 in a FF or Rew mode operation.

(II) Cam Switch Mechanism Referring to Figs. 9 and 10, the cam switch mechanism D includes an exclusive printed circuit board 188 for controlling the position of the slide base 106, and a cam 190 having a predetermined contour. The cam 190 is rotatably mounted at a mounting portion 190a thereof to a boss 188a of the printed circuit board 188 by means of a screw 192. This integral unit is removably mounted on a lower end portion of the shaft 156 which is associated with the worm wheel 154 of the slide base drive section C. Formed in the mounting portion 190a of the cam 190 (which defines the center of rotation) is a recess 190b in which an engaging portion 194 mounted on the worm wheel shaft 156 is engageable.The circuit board 188 is fastened to the chassis base 70 by means of female screws (not shown) while positioning a roller 196 which extends downwardly from the projection 104 of the slide base as shown in Fig. 5 to face a predetermined portion of the outer periphery of the cam 190. As a result, the cam switch mechanism B is mounted to the chassis base 70.

As shown in Figs. 9 and 10, the printed circuit board 188 carries thereon arcuate printed patterns 198a, 198b and 198c which are concentrically arranged about the boss 188a. The radially innermost pattern (GROUND) 198a is for grounding, the intermediate pattern (ACT 1) 198b is for Play and Stop modes, and the outermost pattern (ACT 2) 198c is for FF and Rew modes. A brush 200 is carried on the underside of the cam 190 and provided with three electrodes 200a, 200b and 200c which respectively are associated with and slidable on the printed patterns 198a, 198b an 198c. As described later, as the cam 190 is rotated, the electrodes 200b and 200c detect the beginnings and ends of their associated printed patterns to control the stop position of the slide base 106.

As described above, the cam switch mechanism D comprises an integral arrangement of the cam 190, brush 200, and exclusive printed circuit board 188 which is independent of a printed circuit board adapted for control, not shown. Such a unit can be easily mounted on the shaft 156 of the worm wheel 154 and, in addition, eliminated deformation of the electrodes of the brush 200 and contamination of the circuit board 188 in the production line to thereby free the cam switch mechanism D from malfunction.

(III) Slide Base Position Control Mechanism Referring to Figs. 11 and 12, a slide base position control mechanism is shown. As shown in Fig. 11, mode signals generated by manipulation of the button group 18 shown in Figs. 1A and 1B are applied to a central processing unit (CPU) 202. Also applied to the CPU 202 are signals which represent the beginnings and ends of the patterns 198b (ACT 1) and 198c (ACT 2) provided on the circuit board 188 and detected by the electrodes 200a and 200b of the brush 200 due to rotation of the cam 190. The CPU 202 in turn delivers signals to a slide base driver 204 for driving the motor 142 responsive to a selected mode and to a capstan motor driver 206 for driving the motor 84 associated with the capstan.

The operation of the slide base position control mechanism will be described with reference also made to Figs. 13 and 14. When the power source of the tape recorder TR is turned on, the motor 142 is driven to rotate the cam 190 and brush 200 with the result that the cam 190 is brought to a stop at a position where the ACT 1 and ACT 2 become high level at the same time as shown in Fig. 14, that is, where the electrodes 200a-200c of the brush 200 are positioned at a point s as shown in Fig. 12. In this condition, the slide base 106 is held in the solid line position as shown in Fig. 3. In the event when the signal levels of the ACT 1 and ACT 2 have failed to simultaneously become high level, the CPU 202 drives the motor 142 via the slide base driver 204 to rotate the cam 190 counterclockwise until the ACT 1 and ACTA 2 become high level.As a result, the cam pin 196 on the projection 104 of the slide base 106 shown in Figs. 3 and 5 is moved to the radially outermost position of the cam 190, thereby causing the slide base 106 to retract to and stop at the solid line position of Fig. 3.

As shown in Table below, only when a strobe input terminal STB of the capstan motor driver 206 is high level, the signal delivered to the motor 84 disappears to stop the rotation of the capstan 96. Whenever the terminal STB is low level, the capstan 96 is brought into a drive mode. Then, depending upon the signal levels at mode identification terminals L and R of the driver 206, one of Play, Rew and FF modes is selected and the motor 84 is driven by a signal representative of the selected mode to rotate at a predetermined velocity.

Table

Stop P t a yPlay FF Rew MODE SIGNAL STB high low low low L I low low high R / high |low | low When the Rew/Play button 22 is depressed, the terminal STB becomes high level to drive the motor 84. In the Rew condition of the button 22, both the ACT 1 and ACT 2 become L level at the same time as shown in Fig. 14, so that the cam 190 (electrodes 200a-200c) is rotated counterclockwise and then stops upon detection of the beginning (point f in Fig. 12) of the pattern 198c.As shown in Fig. 13, during a FF mode and a Rew mode the slide base 106 is slightly retracted compared to a Play mode in order to prevent the head 108 from makiro contact with the tape 60, thereby eliminating a load which would otherwise act on the take up reel hub shaft 72.

When the Rew/Play button 22 has been released in a Play mode, ACT 1 is low level and the electrode 200b does not detect the ACT 2. As a result, the cam 190 is further rotated counterclockwise through points r, o, f and s and, then, stopped at a point p where the ACT 1 restores itself to low level. At this instant, based on the relationship shown in Fig. 13, the slide base 106 is moved in the X1 direction from the solid line position of Fig. 3 by the returning forces of the coil springs 128 and 130. This allows the head 108 to make contact with the tape 60. The mechanism is maintained in a Play mode to transport the tape 60 in the Q direction at a constant velocity.

During a FF mode operation, the motor 142 is rotated to drive the cam 190 counterclockwise until it reaches the point f where the ACT 1 becomes low level and the ACT 2 high level. Then, as in the Rew mode operation, the slide base 106 is slightly retracted in the X2 direction from the position associated with the Play mode. The mechanism is thus brought into a FF mode to transport the tape 60 forwardly at a high speed.

As described above, the position of the slide base 106 is controlled by the cam switch mechanism D which cooperates with the slide base 106 and detects the beginnings and ends of printed patterns. Such simplifies the electrical arrangement built in the tape recorder TR, insures positive control over the position of the slide base 106, and cuts down the dimensions and cost of the tape recorder TR. In addition, power-saving soft logic operation is realized by use of the two motors 84 and 142.

The tape recorder TR having the above construction will be manipulated and operated as will be described totally and concretely hereinafter.

(1) The lid 12 is opened as shown in Fig. 1C and, then, the tape cassette TC which is constructed as shown in Figs. 2A and 2B is loaded in the tape recorder TR as indicated by an arrow P.

(2) The power source of the tape recorder TR is turned on. Then, responsive to a control signal, the cam 190 is rotated to a position where the ACT 1 and ACT 2 simultaneously become high level, i.e., point s, and stopped there.

(3) When the Rew/Play button 22 is depressed and released immediately, the terminal STB becomes high level as shown in Table to set up a drive mode. In this condition, the motor 142 is driven to in turn drive the slide base drive mechanism C and, thereby, the cam switch mechanism D. In response to the operation of the mechanism D, the brush 200 associated with the cam 190 is rotated counterclockwise to detect the pattern 198b on the circuit board 188, thereby making the ACT 1 low level. Meanwhile, the electrode 200c does not detect the pattern 198c. As soon as the electrode 200b detects the pattern at the point p, the cam 190 is brought to a halt.

Due to the relationship between the cam rotation angle and the slide base position shown in Fig. 13, the slide base 106 is moved in the X, direction from the solid line position of Fig. 3 by the movement of the cam pin 196 on the slide base 106 which is slidably engaged with the cam 190. This shifts the head 108 to the phantom line position of Fig. 3. As a result, as previously described, the head 108 enters the inlet 44 (46) of the tape cassette TC, while the tape guides 120 enter respectively the thinned portions 44a and 44b (46a and 46b) of the cassette TC to allow the tape 60 to be stably transported. In the course of the movement of the X, direction, the slide base 106 urges one end of the locking members 132 and 134 at its one edge so that the other end of each of the locking members 132 and 134 swings outwardly beyond the associated side wall 70b or 70c of the chassis base 70.Consequently, the locking members 132 and 134 latch the locking portions 28a and 30a of the lid 12 shown in Fig. 1C, thereby latching the lid 12 in the closed position.

Further, while the slide base 106 is moved as mentioned, its one edge depresses the switch section 140 to turn on the amplifier of the tape recorder TR. In the meantime, the cam plate 164 forcibly retracts the ratchet 176 of the one-way clutch mechanism CL1 to prevent it from engaging with the ratchet cam 162 due to rotation of the capstan drive motor 84, as shown in Fig. 8. Therefore, the clutch CL1 is deactivated, or uncoupled, to allow the tape 60 to be transported in the Q1 direction with no undesirable back tension applied to the reel hub shaft 74 on the drive side.

When a Play mode is set up with the lid 12 opened and, then, the lid 12 is closed, the locking members 132 and 134 are further rotated by the locking members 28 and 30 in a direction for closing the lid and, upon arrival at the notches 28a and 30a, mate therewith to lock the lid 12 in the closed position.

(4) As the FF button and Rew/Play button 22 are continuously depressed, the mode identification terminals L and R become respectively low level and low level and high level and low level so that the motor 84 is rotated at a predetermined rate. In the meantime, the cam 190 is rotated counterclockwise with the result that the electrodes 200a-200c of the brush 200 detect the beginnings and ends of their associated patterns on the circuit board 188. The cam 190 and electrodes 200-200c are stopped at the points f and r of Fig. 12. Due to such a rotation of the cam 190, during a FF mode and a REW mode, the head 108 is brought to a halt at a position slightly retracted in the X2 direction relative to a position for a Play mode, as shown in Fig. 13.

In this position the head 108 remains clear of the tape 60 to insure stable tape transport.

(5) In a stop mode, the terminal STB becomes high level to deenergize the motor 84, while the slide base drive mechanism causes the cam 190 to rotate counterclockwise again in order to retract the slide base 106 to the solid line position of Fig. 6. Then, as shown in Fig. 14, both the ACT 1 and ACT 2 become high level and, as a result, the cam 190 stops its rotation when the electrodes 200a-200c have reached the point s of Fig. 12.

In summary, a one-way clutch mechanism of the present invention is constructed such that when a rotary member is rotated in an inoperative direction of the clutch, a locking member provided on the drive rotary member surely cancels engagement of the rotary member with a driven rotary shaft. Hence, where the clutch is associated with a reel hub shaft of a tape recorder, it frees a reel hub shaft on a take-up side from loads except for the back tension which usually acts on a tape in a FF/Rew mode operation, thereby enhancing durability of the tape recorder and eliminating damage to the tape.

Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.

Claims (5)

1. A one-way clutch mechanism for rotating a rotary shaft which is rotatably supported by a base member of a device in which said mechanism is installed, comprising: a bearing mounted on the base member for rotatably supporting the rotary shaft; a ratchet cam provided with a plurality of engaging portions along a circumference and mounted on the rotary member; a rotary member rotatably supported by said bearing; a cam plate rotatably supported by the bearing and provided with a guide portion, said cam plate being frictionally engaged with and rotatable relative to said rotary member; and a rotatable locking member pivotted at one end to the rotary member and configured at the other end to selectively lock the engaging portion of the ratchet cam, said locking member being guided by and retained by the guide portion of the cam plate; whereby when the rotary member is driven to rotate in one direction, the locking member is rotated along the guide portion of the cam plate to release the rotary shaft and the rotary member from each other.

2. A one-way clutch as claimed in claim 1, wherein the device comprises a magnetic tape recorder, the rotary shaft comprising a reel hub shaft of the tape recorder.

3. One-way clutch substantially as described in the description with reference to the appropriate drawings.

4. A tape recorder and/or player having a clutch, such as a pawl and ratchet arrangement, in the drive to at least one of the reel hubs and means to release the clutch in response to the force applied by the tape to the respective reel when that reel is serving as a tape supply reel at least during a fast winding or rewinding operation.

5. A tape recorder and/or player substantially as described in the description with reference to the drawings.