JPH0261848A - Autostop mechanism for tape recorder - Google Patents

Abstract

PURPOSE:To confirm a disappearance of revolving force of a sensor and to prevent malfunction by oscillating slightly a sensor lever with a confirmation device of simple constitution and separating temporarily a degree stopper pin from its placed degree stopper part in a double-cam hole. CONSTITUTION:Fitting shafts 3a-3c on a autoshaft-off substrate 3 in the title autostop mechanism are rotatively or freely turnably fitted with a cam gear 6, the sensor lever 7 and a control lever 8. The fitting shaft 3a of the substrate 3 is freely rotatively fitted into a center shaft hole of this cam gear 6. Then, the cam gear 6 has three cam surfaces 6a-6c, whereas the cam surface 6a is placed eccentrically around a center and formed in an approximately ellipsoidal shape. And, a 1st driven piece 7a of the sensor lever 7 is guided by the cam surface 6b outwardly from the middle of a radius, while a 2nd driven piece 7c of a confirmation mechanism is guided by the cam surface 6c located in the vicinity of the outer circumference and slightly inward, where the appearance of the sensor turning force is confirmed by the information mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an auto-stop mechanism for a tape recorder in which the stop mechanism operates when the tape stops running.

[Prior art]

The 12th automatic stop mechanism for conventional tape recorders
As shown in the figure, a heart-shaped bifurcated cam hole 9e is formed in the sensor 9, which is rotationally displaced in relation to the winding direction of the tape (not shown), and the sensor is constantly oscillated in the bifurcated cam hole 9e, regardless of the tape running. Sake the perpendicular pin 7b of the lever 7,
When the rotational force of the sensor 9 disappears, the perpendicular pin 7b abuts the perpendicular part 9h in the bifurcated cam hole 9e, thereby restricting the swinging stroke of the sensor lever 7, thereby providing an auto-stop mechanism that performs a stop operation.

Assuming that the sensor 9 is receiving rotational force in the direction of the solid arrow in this auto-stop mechanism, the sensor lever 7 is being swung by the cam surface 6a, and the contact pin 7b is now in the first position.
It is moving in the direction of the arrow in the explanation of Figure 0. Further, the bifurcated cam hole 9e is about to move in the direction of the solid arrow. If this continues, the perpendicular pin 7b will enter the back end 9g of the bifurcated cam hole 9e, but if you now reverse the tape running direction, the sensor 9 will receive the opposite rotational force, Since the bifurcated cam hole 9e moves in the direction of the dotted line in FIG. 10, the deflection pin 7b may collide with the deflection portion 9h of the bifurcation cam hole 9e. If there is a collision during direction change, the deflection pin 7h will remain on the deflection portion 9h of the bifurcated cam hole 9e, resulting in an automatic stop operation.

Furthermore, if there is slack in the tape, there will be a time when the sensor 9 has no rotational force, which may lead to malfunctions.

[Purpose of the invention]

In view of the above-mentioned drawbacks, the present invention provides a confirmation mechanism that slightly swings the sensor lever to confirm the disappearance of the rotational force of the sensor after the changeover between the changeover pin and the changeover portion. The purpose of this invention is to propose an auto-stop mechanism for a tape recorder that prevents malfunctions during conversion or due to tape slack.

[Structure of the Invention] The present invention includes a sensor formed with a two-pronged cam hole that is rotatably displaced in relation to the tape winding direction, and a sensor that is fitted into the two-pronged cam hole that is always oscillated regardless of the tape running. and a sensor lever having a passage pin, and when the rotational force of the sensor disappears, the perpendicular pin passes through the passage part in the bifurcated cam hole, and the swinging stroke of the sensor lever is restricted and the stop operation is performed. In the stop mechanism that performs this, a confirmation mechanism is provided which swings the sensor lever slightly to confirm the disappearance of the rotational force of the sensor after the contact pin and the contact portion have changed direction. be.

〔Example〕

The present invention will be explained below with reference to an illustrated embodiment. FIG. 1 is an exploded perspective view showing the auto-stop mechanism 100 and related mechanisms, FIG. 2 is a perspective view of the auto-stop mechanism 100 removed from the board 1, and FIG. 3 is a perspective view of the auto-stop mechanism. In the tape recorder, as shown in FIGS. 1 to 3, a head substrate 10 is mounted on a substrate 1, and a push button 11 is fixed among a plurality of operation levers to which push buttons for selectively performing various operations of the tape recorder are fixed. The head substrate 10 is moved back and forth using the recording/reproducing operation lever 2 or the like. An auto-shutoff board 3 in which various elements of the auto-stop mechanism 100 are incorporated is attached to the lower side of the board 1.

Furthermore, a motor 12 is attached to a substrate (not shown) below the substrate 1. motor! 2 is rotated at a constant speed, and the flywheel 14 is rotated in the direction of the arrow via the bell) 13. A capstan shaft 15 is fixed to the flywheel 14, and the capstan shaft 15 projects from the upper surface of the substrate 1. An idler 4 protruding from the substrate 1 is rotated in the direction of the arrow by a flywheel 14 or a motor 12b) by a suitable transmission means. Reel spindles 16 and 17 rotatably provided on the substrate 1 are fitted with hubs for tape windings on the take-up side and the supply side, respectively, when a cassette (not shown) is installed. A gear 18 is attached to the reel spindle 16 via means such as friction transmission, and a take-up idler 19 for winding the tape during constant-speed feeding is engaged with the gear 18.

The take-up idler 19 is rotatably supported on the lever 5. The lever 5 is rotatably supported on the base plate l by a shaft 20. The take-up idler 19 transmits low-speed rotation from the small diameter gear 43 of the idler 4 to the reel spindle 16. The friction transmission means is such that there may be a speed difference between constant speed tape feeding and constant rotation winding of the reel spindle 16.

Although not shown, a means such as friction transmission is separately provided so that even if the tape reaches its end and the reel spindle rotation stops, the motor, flywheel, and other necessary parts continue to rotate.

A pinch arm 20 is rotatably supported on the head substrate 10, and a pinch roller 21 is rotatably supported on the pinch arm. The pinch roller 21 moves forward during recording and reproduction, pinches the tape between it and the capstan shaft 15, and feeds the tape at a constant speed. Further, an erasing head 22 and a recording/reproducing head 23 are fixed on the head substrate 10.

To explain the auto-stop mechanism, a cam gear 6, a sensor lever 7, and a control lever 8 are rotatably or rotatably attached to mounting shafts 3a, 3b, and 3C of an auto-shutoff board 3.

The center shaft hole of the cam gear 6 is connected to the auto shut-off board 3
It is rotatably fitted onto the mounting shaft 3a of.

The cam gear 6 has three cam surfaces. Cam surface 6a
is approximately elliptical in shape, surrounding the center and placed eccentrically. The cam surface 6b guides the first driven piece 7a of the sensor lever 7 outward from approximately the middle in the radial direction.

The cam surface 6C is located near the outer periphery and guides the second follower piece 7C of the confirmation mechanism slightly inward.

The sensor lever 7 has a rotation shaft hole approximately in the middle, and is rotatably fitted onto the mounting shaft 3b of the auto-shutoff board 3. The sensor lever 7 has a shape consisting of branches extending in both directions and techniques extending laterally.

A first driven piece 7a protrudes downward at the tip of a branch extending laterally.
are related to the cam surfaces 6a and 6b of the cam gear 6.

At the tip of the branch extending forward, there is a perpendicular pin 7 that protrudes upward.
b, which is related to the heart-shaped bifurcated cam hole 9e of the sensor 9.

Also, the second driven piece 7 of the confirmation mechanism protrudes downward near the tip.
c, which is related to the cam surface 6C of the cam gear 6.

The branch extending backward is bifurcated, one tip 7d is connected to the locking plate 24, and the other elastic branch tip 7d is connected to the locking plate 24.
e is opposed to the switch plate 25. The locking plate 24 and the switch plate 25 are arranged in an overlapping manner, and each has a spring 26, 27.
It is biased to the right in Figure 1.

The control lever 8 has a rotation shaft hole approximately in the center, has branches extending in both directions, and is rotatably attached to the mounting shaft 3C of the auto-shutoff board 3.

The control lever 8 has a tip 8a that is connected to other members, and engaging portions 8b, 8c, and 8d. These will be explained in the operation explanation.

A spring 28 is hung between the sensor lever 7 and the control lever 8, and generates a counterclockwise rotating force in both levers.

Therefore, the sensor lever 7 normally has its driven piece 7a in contact with the cam surface 6a of the cam gear 6.

The sensor 9 is a nearly Y-shaped lever, and has a shaft 9a in the center that projects upward, and is rotatably fitted into a shaft hole 29a spaced from below the support shaft 29 of the reel spindle 16. There is.

From one tip of the Y-shaped technique there is a springy branch 9b that makes a U-turn toward the center. When the assembled auto-stop mechanism 100 is attached to the board 1, the convex portion 3d provided on the auto-shut-off board 3
It is arranged so as to push up the tip of the spring branch 9b. Two protrusions 9c stand on both sides of the shaft 9a.

The protrusion 9c passes through the fan-shaped hole 1a drilled in the base plate 1 and connects the lower surface 30 of the gear 30 that moves together with the reel spindle 16.
It has reached a.

And, due to the spring properties of the spring branches 9b, they are always lightly pressed together.

Therefore, the sensor 9 can be rotated within a certain range in the direction of rotation of the reel spindle 16.

One protrusion 9d stands substantially below one of the protrusions 9c.

The tip 8a of the control lever 8 comes into contact with the protrusion 9d, giving a counterclockwise rotational force to the sensor 9. The magnitude of the rotational force is set to be larger than the rotational force generated by pressure contact with the reel spindle 16.

Another branch of the Y-shaped technique is a heart-shaped bifurcated cam hole 9e with an extension.

A perpendicular pin 7b at the tip of the sensor lever 7 is inserted into the bifurcated cam hole 9e.

There is a projecting piece 5a below the end of the lever 5 on which the winding idler +9 is placed. When the take-up idler 19 comes to the position for winding, the protruding piece 5a pushes the engaging portion 8b of the control lever 8, giving the control lever a clockwise rotational displacement.

The shaft 31 of the idler 4 is supported by a lever 32, and the lever 32 is supported by a shaft 33 through a long hole 32a, so that the position of the lever 32 can be moved for fast forwarding or rewinding the tape.

When the position moves and the idler 4 begins to transmit fast forward or rewind, the engaging portion 32b of this lever 32
1 or 32c is the engaging portion 8c of the control lever 8;
Alternatively, press 8d to give the control lever 8 a clockwise rotational displacement.

In any case, when the idler 4 is in the transmission state, the control lever 8 is rotated clockwise and the sensor 9 is released from the control lever 8.

The locking plate 24 holds the operating lever 2 to which the push button 11 is fixed in an operating state. The switch plate 25 is configured such that a switch 34 is turned on when the push button 11 is pressed to an operating state.

Ends 24a and 25a of the locking plate 24 and the switch plate 25
are opposed to the bifurcated tips 7d and 7e of the sensor lever 7.

When the sensor lever 7 rotates clockwise, the lock plate 24 releases the lock of the push button 11 by pushing the sensor lever 7, and the switch plate 25 continues to hold the switch 34 in the ON state.

To explain the operation of the auto-stop mechanism of a tape recorder, FIGS. 4 to 9 show the positions of each mechanical member in relation to the rotation of the cam gear 6. For example, in order to perform a playback operation, Push button U with spring 3 in Figure 1.
Suppose you push it against 5.

The push button ■ and the operating lever 2 move the members necessary for operation, and the protruding piece 2a of the operating lever 2 engages the locking portion 24 of the locking plate 24.
b and is locked.

At the same time, the switch plate 25 is displaced by the protruding piece 2a' of the operating lever 2, and the switch 34 is turned on. Projecting pieces 2a, 2a'
are identical protrusions. The locking plate 24 and the switch plate 25 are shown side by side in order to make the explanation easier to understand.

When the operation starts in this manner, the cam gear 6 is rotated in the direction of the arrow.

The reel spindle 16 also rotates, and the sensor 9, which is in pressure contact with the reel spindle 16 via the protrusion 9c, also receives rotational force.

The direction of rotation of the sensor 9 is, for example, in the direction of the solid line arrow in FIG. 4 in the case of playback and fast forwarding, and in the opposite direction of the dotted line arrow in the case of rewinding.

Before the reel spindle 16 rotated, the sensor 9 received rotational force in the direction of the arrow at the tip 8a of the control lever 8, but once the rotation was transmitted to the reel spindle 16, the control lever rotated clockwise. Due to the dynamic displacement, the sensor 9 is no longer affected by this.

From now on, the operation will be explained starting from the state shown in FIG. The sensor lever 7 receives a counterclockwise rotational force from a spring 28, and the figure shows the state when the first follower piece 7a is in contact with the farthest point of the cam surface 6a of the cam gear 6. . The perpendicular pin 7b at the tip of the sensor lever 7 is located at the base 9f of the extension of the bifurcated cam hole 9e of the sensor 9.

When the cam gear 6 rotates in the direction of the arrow, the sensor lever 7 rotates counterclockwise along the regression of the cam surface 6a.
Figure 5 states and noodles.

During this time, if the reel spindle 16 is rotating, that is, if the tape is being fed, rotational force is being applied to the sensor 9, so that the wall surface of the bifurcated cam hole 9e is at the tip of the sensor lever 7 inserted therein. It always aligns with the pin 7b at every turn.

Therefore, when the sensor lever 7 is rotated most counterclockwise as shown in FIG. It reaches one of the rear ends 9g of the cam hole 9e.

Which end is located depends on the direction of rotation of the reel spindle 16, that is, whether the tape is winding, early spring winding, or rewinding. In the case of Fig. 5, it is in the state of winding or early spring winding.

Next, the sensor lever 7 is moved to the cam surface 6 of the cam gear 6.
A clockwise rotational displacement is performed by a.

The first driven piece 7a of the sensor lever 7 passes between the two cam surfaces 6a and 6b of the cam gear 6.

The perpendicular pin 7b at the tip of the sensor lever 7 is connected to the sensor 9.
It advances along the bifurcated cam hole 9e and reaches the base 9f of the extension.

At this time, the sensor 9 is pulled back to the initial position against the rotational force received from the reel spindle 16.

In this way, the state shown in FIG. 4 is reached, and the states shown in FIGS. 4 and 6 are repeated while the tape is running.

Assume that the end of the tape has now been reached and the reel spindle 16 has stopped.

After the state shown in FIG. 4, the sensor lever 7 begins to rotate counterclockwise.

However, this time, since the reel spindle 16 is stationary, the sensor 9 does not receive rotational force and remains at the same position.

Then, the perpendicular pin 7b at the tip of the sensor lever 7 advances in the middle of the bifurcated cam hole 9e and collides with the perpendicular part 9h protruding from the center of the heart shape.

In other words, counterclockwise rotation of the sensor lever 7 is obstructed midway. This state is shown in FIG.

The motor I2 continues to rotate, and the cam gear 6 continues to rotate as shown in FIG.

The first driven piece 7a of the sensor lever 7 is separated from the cam surface 6a. Then, the cam surface 6b approaches.

This time, the sensor lever 7 is largely rotated clockwise by the cam surface 6b. This state is shown in FIG.

When the sensor lever 7 rotates significantly clockwise, the tip 7d of the bifurcated branch pushes the end 24a of the locking plate 24 to unlock the operating lever 2, and the tip 7d of the bifurcated branch presses the end 24a of the locking plate 24 to unlock the operating lever 2.
prevents the switch plate 25 from returning and switches O
Maintain the N state.

When the cam gear 6 continues to rotate further, the first sensor lever 7
The driven piece 7a passes the end edge of the cam surface 6b and reaches the cam surface 6a.
I feel depressed.

Since the sensor lever 7 rotates counterclockwise, its bifurcated ends 7d and 7e also stop pressing the locking plate 24 and the switch plate 25 and are released.

When the push button 11 is released, the idler 4 and the take-up idler 19 also return to their positions where they stopped transmitting rotation, so the control lever 8 rotates counterclockwise and applies a counterclockwise rotational force to the sensor 9.

The control lever 8 causes the sensor 9 to operate only when the reel spindle 16 is in a state where it should rotate, thereby preventing automatic stop when unnecessary.

This completes the return to the state before the button was pressed, and the next operation is now possible. FIG. 9 shows the state at this time.

The auto-stop mechanism works in this way, but in actual use there is a small chance that the auto-stop will occur accidentally.

FIG. 1O explains the occurrence of a malfunction, and shows the perpendicular pin 7b at the tip of the sensor lever 7 and the bifurcated cam hole 9e of the sensor 9 enlarged.

Younger brother Figure 10 is about to change from the state in Figure 4 to the state in Figure 6.

In FIG. 1O, the perpendicular pin 7b is moving in the direction of the arrow.

The bifurcated cam hole 9e is about to move in the direction of the solid arrow.

If this continues, the situation shown in FIG. 5 will occur, but now suppose that the tape running direction is reversed. In this example, winding or early spring taking is changed to rewinding.

Then, since the rotation of the reel spindle 16 is reversed, the bifurcated cam hole 9e moves in the direction of the dotted arrow until its wall contacts the perpendicular pin 7b.

Then, the vibrator 7b that is being transformed enters one of the rear ends 9g' opposite to the previous one, and becomes the state shown in FIG. 4, thus continuing the new operation.

However, since the perpendicular pin 7b is moving in the direction of the arrow, if you are unlucky, the perpendicular part 9h of the forked cam hole 9e is moving.
may collide.

If the transmission of rotational force from the reel spindle 16 to the sensor 9 is sufficiently large, even if there is a collision, rotation will occur and the hit pin 7b can be inserted into the rear end 9g'.

However, since we do not want to apply unnecessary load to the reel spindle 16, the force transmitted to the sensor 9 is kept small.

Therefore, if there is a collision during direction change, the contact pin 7b often remains on the contact portion 7h of the bifurcated cam hole 9e.

In this case, the state shown in FIG. 6 is reached, and as explained above, the auto-stop operation shown in FIG. 7 and the subsequent steps will be performed.

In other words, the auto-stop will occur by mistake.

The present invention prevents this malfunction by using the following confirmation mechanism.

The confirmation mechanism uses the cam surface 6c of the cam gear 6 to swing the second driven piece 7c of the sensor lever 7 slightly after the percussion pin 7b and the percussion part 9h collide with each other.
It is configured to confirm the disappearance of the rotational force.

The operation of the confirmation mechanism is shown in FIG. 6 when the cam surface 6C of the cam gear 6 approaches the second driven piece 7c projecting downward from one branch of the sensor lever 7.

This will eventually come into contact, but at this time the sensor lever 7 will be rotated slightly clockwise.

Therefore, the perpendicular pin 7b resting on the perpendicular abutting portion 9h of the heart-shaped bifurcated cam hole 9e is slightly separated.

At this time, reel spindle 1 is used to feed the tape in the opposite direction.
6 is rotating, the sensor 9 rotates, and the perpendicular pin 7b then enters the inner end 9g' of the bifurcated cam hole 9e.

Therefore, there is no auto-stop.

If the reel spindle 16 has actually stopped at the end of the tape, the sensor lever 7 will be slightly rotated clockwise by the cam surface 6C of the cam gear 6, and the perpendicular pin 7 will be rotated slightly.
Since the sensor 9 does not move even if b moves away from the contact part 9h of the bifurcated cam hole 9e, when the cam surface 6C passes, the contact pin 7b will be placed on the contact part 9h again, and the second The state shown in Fig. 7 is reached, and from then on, auto-stop is performed.

The cam surface 6C of the mugger 6 can come into contact with the second driven piece 7c of the sensor lever 7 when the contact pin 7b of the sensor lever 7 is placed on the contact part 9h of the bifurcated cam hole 9e. Then, press the perpendicular pin 7b of the sensor lever 7.
When the cam surface 6c has already entered the inner end 9g of the bifurcated cam hole 9e, the cam surface 6c passes through the side of the second subordinate piece 7c and does not interfere with each other.

The path of this cam surface 6c is shown by the dotted arrow in FIG.

In FIG. 11, the horizontal axis represents the rotation of the cam gear 6 or the passage of time, and the vertical axis represents the amount of clockwise rotational displacement of the sensor lever 7.

The amount of rotational displacement is shown by a dotted line. If the reel spindle 16 is rotating, the first driven piece 7a of the sensor lever 7 will be in constant contact with the cam surface 6a as described above, so the amount of rotational variation will follow the dotted line A-B-C. - It progresses as in D.

If the sensor 9 is stopped, a collision occurs between the perpendicular pin 7b and the perpendicular contact portion 9h of the bifurcated cam hole 9e at point B.

Thereafter, the sensor lever 7 is not rotated, so the process progresses as indicated by the dotted line E.

Next, the cam surface 6C comes into contact with the second driven piece 7C, so the sensor lever 7 rotates further clockwise.

This progresses as shown by the dotted line F.

When the cam surface 6C passes and the sensor 9 stops, a collision occurs again at the contact portion 9h, and the sensor lever 9
The rotation remains at the G position, and the subsequent cam surface 6b causes a large rotation as shown in the H position.

If the sensor 9 rotates while passing point F, the collision at the abutment part 9h will no longer occur, and the abutment pin 7b will enter the rear end 9g' of the bifurcated cam hole 9e, so the sensor lever 7 The rotation of will be at the same position as from C, and will proceed as follows.

One of the causes of malfunction is that the tape running direction changed just before point B, but this will be reconfirmed and corrected later at point F.

Another object of the present invention, which is an operation for preventing malfunctions due to tape slack, is as follows.

Assume that an operation is performed to wind the tape on the reel spindle to which the sensor 9 is not attached, in this case the rewind side reel spindle 17.

If there is slack in the tape, the reel spindle 16 on which the sensor 9 is located will not rotate until the slack is taken up.

In other words, even if the tape stops, the auto-stop mechanism may malfunction.

How many times does the pin 7b rest on the contact portion 9h of the bifurcated cam hole 9e during the transition from the state shown in FIG. 4 to the state shown in FIG. 5? The cam gear 6 changes from the state shown in FIG. It's the location. This is when it is rotated about 60 degrees.

During this time, if the reel spindle 16 remains stopped due to tape slack, the contact pin 7b will rest on the contact portion 9h of the bifurcated force hole 9e, resulting in an automatic stop.

However, since the cam surface 6C and the second driven piece 7C will be reconfirmed later at F, the reel spindle 1
6 should rotate.

The amount of tape slack is allowed to be approximately 3.5 times that between AB, and malfunctions caused by this are greatly improved.

When the auto-stop mechanism of the tape recorder is configured as described above, the sensor lever 7 is slightly swung by the simple confirmation mechanism consisting of the cam surface 6C and the second driven piece 7C, and the contact portion of the bifurcated cam hole 9e is Power pin 7 on 9h
By temporarily releasing b, it is confirmed that the rotational force of the sensor 9 has disappeared, and malfunction is prevented.

〔Effect of the invention〕

Since the present invention is constructed as described above, the sensor lever is slightly swung by a simple confirmation mechanism, and the perpendicular pin resting on the perpendicular part of the bifurcated cam hole is temporarily released. Therefore, it is possible to provide an auto-stop mechanism for a tape recorder that is effective in preventing malfunctions by confirming the disappearance of the tape recorder.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an exploded perspective view of the auto-stop mechanism of a tape recorder, FIG. 2 is an exploded perspective view of the tape recorder with the auto-stop mechanism removed, and FIG. 3 is an exploded perspective view of the auto-stop mechanism of the tape recorder. The perspective view, Figures 4 to 9 are operation explanatory diagrams of the auto-stop mechanism, and the 1st O
The figure is an explanatory diagram of the sensor's operation. Figure 11 is an operational diagram with the horizontal axis representing the rotation of the cam gear or the passage of time, and the vertical axis representing the clockwise rotational displacement of the sensor lever. Figure 12 is the conventional FIG. 3 is a plan view of the main parts of the auto-stop mechanism. 6c, 7c...Confirmation mechanism, 7...Sensor lever 7b...Performance pin, 9...Sensor, 9e...
Two-pronged cam hole, 100...Auto stop mechanism. Applicant Sankyo Seiki Seisakusho Co., Ltd.

Claims (1)

[Claims] 1. A sensor lever having a sensor formed with a two-pronged cam hole that rotates in relation to the tape winding direction, and a perpendicular pin that fits into the two-pronged cam hole that swings at all times regardless of tape running. In the stop mechanism, wherein when the rotational force of the sensor disappears, the perpendicular pin hits the perpendicular part in the bifurcated cam hole, and the swinging stroke of the sensor lever is restricted to perform a stop operation. An auto-stop mechanism for a tape recorder, characterized in that a confirmation mechanism is provided which swings the sensor lever slightly to confirm disappearance of rotational force of the sensor immediately after the perpendicular pin and the perpendicular part contact each other. .