JPH0237138Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved device for detecting the end of a tape in a tape recorder.

Generally, in a tape recorder, the end of the tape is detected to shut off the power, restore operation, or generate an alarm.

Various techniques have been proposed for detecting the end of the tape, which is the basis for performing such operations. For example, a magnet is attached to a rotating body that has a slip mechanism and rotates as the tape runs, and a Hall element converts the change in magnetic pole due to the rotation into voltage, and a detection circuit detects the presence or absence of that voltage. By detecting this, the tape can be stopped running, i.e.
Devices that detect the end of a tape are often used.

However, such a tape end detection device requires members and circuits that account for a considerable proportion of the cost, and also consumes power.

The present invention is intended to contribute to cost reduction, reliability improvement, and durability improvement by enabling the tape end detection to be performed purely mechanically, and will be described in detail below.

In the figure, 1 is a pulley attached to the motor shaft (not shown), 2 is a belt, 3 is a pulley, 4 is a gear fixed to the pulley 3, and 5 is a power transmission through frictional coupling with the pulley 3. 6 is a shaft of gear 5, 7 is a swinging lever that is frictionally connected to shaft 6, 8 is a cam gear that meshes with gear 4, and 9 is formed on cam gear 8. A wall-like outer cam, 9a is a deformed portion of the outer cam, 10 is a wall-like inner cam also formed on the cam gear 8, 11 is a tape winding side gear that meshes with the gear 5, 12 is a tape winding side reel shaft, 13 is gear, 14 is tape feeding side gear, 15
16 is a detection lever engaged with the lever 7; 17 is a guide pin that is planted on the lever 7 and slides into contact with the inner wall of the cam 9; 18 is the detection lever 16.
19 is a guide pin,
Reference numerals 20 indicate switches operated by the detection lever 16, respectively.

Note that the inner cam 10 has an arcuate cross section parallel to the cam gear 8, and the inner cam 10 is provided at a position eccentric from the rotation center of the cam gear 8.

In this embodiment, if the pulley 3 is now rotating in the direction of arrow A, the gears 4 and 5 will also rotate in the same direction.

Gear 11 meshing with gear 5 rotates in the direction of arrow B to wind up the tape.

Due to the rotation of the gear 5, a displacement force in the direction of arrow C is applied to the lever 7 which is frictionally engaged with the gear 5, and the guide pin 17 at the tip of the lever 7 is moved by the outer cam 9.
contact the inner wall.

Since the cam gear 8 meshes with the gear 4, it rotates in the direction of arrow D. Due to this rotation, the guide pin 17 comes into contact with the inner wall of the outer cam 9 at a portion other than the deformed portion 9a at a certain time, and the lever 7 becomes the first transition position. Further, the guide pin 17 will come into contact with the inner wall of the deformed portion 9a at a certain time, and at that time, it will be pushed leftward from the current position, and the position of the lever 7 will become the second transition position. Therefore, while the tape is running, the lever 7 slightly swings left and right between the first transition position and the second transition position, and the detection lever 16 repeats the left and right movement, but this movement activates the switch 20. It will not be done.

Now, when winding of the tape is completed, gear 11 and gear 5 can no longer rotate. Therefore, a slip occurs between the pulley 3 and the gear 5,
In this state, the pulley 3 continues to rotate further.

If the pulley 3 continues to rotate, the cam gear 8 will also rotate, but at this point, since the gear 5 is stopped, there is no force pushing the swing lever 7 in the direction of arrow C. The movement of cam 7 is restricted only by the force received by guide pin 17 that is in contact with the inner wall of outer cam 9. When the pin 17 comes into sliding contact with the deformed portion 9a of the outer cam 9, the swing lever 7 moves to the second displacement position in the direction opposite to the arrow C. Further rotation of the cam gear 9 thereafter causes the pin 17 to leave the deformed portion 9a and remain in its second displacement position.

In this state, the cam gear 8 continues to rotate, so the pin 17 comes into contact with the inner wall of the inner cam 10 at the second transition position, and as the cam gear 8 rotates, the pin 17 moves toward the center. The swinging lever 7 moves further in the direction opposite to the arrow C.
Therefore, the detection lever 16 is moved largely to the third shift position on the left side of the figure, and the switch 20 is operated in sequence.

In addition, after the pin 17 is wound up by the inner cam 10 and largely moves to the third displacement position in the direction opposite to the arrow C, the pin 17 is moved to the cam gear 8 in the inner cam 10.
Since only the part closest to the center of the object comes into contact with the object, it will stop at that position. Therefore, even if the cam gear 8 is configured to constantly rotate to simplify the mechanism, the swing lever 7, detection lever 16, and switch 20 will maintain their state until the tape starts running again, thereby preventing unnecessary operations. It is very durable because there is no

The operation of this switch 20 may be used to perform an appropriate automatic operation such as so-called auto-shut-off.

As can be seen from the above explanation, according to the present invention, detection of the end of the tape in a tape recorder and stopping due to tape winding can be performed entirely mechanically, and the number of parts required for this is small. Furthermore, since it is inexpensive, the cost is lower compared to, for example, a rotating body with a magnet, a Hall element, or other detection circuits. Since the tape is stopped at the third displacement position after the tape is displaced in the opposite direction to the displacement force and until the tape resumes running, the second gear is always rotated to simplify the mechanism. Also, since there are no unnecessary operations,
It works reliably even if used as is for a long period of time.

[Brief explanation of the drawing]

The figure is an explanatory plan view of a main part of an embodiment of the present invention. In the figure, 3 is a pulley, 4 and 5 are gears, 6 is a shaft, 7 is a lever, 8 is a cam gear, 9 is an outer cam,
9a is a deformed part, 10 is an inner cam, 11 is a gear,
12 is the reel shaft, 16 is the detection lever, 17 is the pin,
20 is a switch.

Claims (1)

[Claims for Utility Model Registration] A first gear that is rotationally driven from a power source via a slip mechanism to rotate a reel shaft; a second gear that is rotationally driven by the power source; and a rotation of the first gear. a swinging lever to which a displacement force is applied in a predetermined direction and the displacement force disappears when the rotation of the first gear stops; a first cam that regulates from a first displacement position to a second displacement position in a direction opposite to the direction of the displacement force with respect to the first displacement position while the first gear is rotating; When the second gear rotates with the swing lever in the second displacement position regulated by the first cam of the lever and the first gear stopped, the swing lever engages with the swing lever. a second cam that further moves the rocking lever from the second displacement position to a third displacement position in a direction opposite to the direction of the displacement force, and stops the rocking lever at the third displacement position; A tape end detection device comprising: a detection lever that is connected to the swing lever and operates a switch when the swing lever is moved to a third displacement position by the second cam.