JPS581877Y2 - cassette tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cassette tape recorder, and particularly to a tape recorder having a mechanism for automatically canceling the rewinding operation when the scale of a counter indicating the amount of travel of the magnetic tape shows a predetermined value.

When recording from the middle of a magnetic tape using a tape recorder and checking the recorded content, it is necessary to rewind the magnetic tape at the recording start position casing.

This rewinding operation is performed while watching the scale on a counter that displays the amount of travel of the magnetic tape, but because the magnetic tape travels at such a fast speed, it is difficult to stop the rewinding of the magnetic tape accurately at the recording start position. It is.

Recently, as a device to accurately stop rewinding at the start position of a magnetic tape, a switch that is closed when the scale of a counter shows a predetermined value is used to cause a plunger to perform a suction operation to perform rewinding operation. A version has been implemented to remove this.

The plunger that performs this operation constitutes a so-called automatic stop device that returns the drive mechanism to a stopped state by utilizing the characteristic of cassette tape recorders that the rotation of the reel shaft stops at the end of tape winding. Often used as a plunger.

The rotation detection mechanism that constitutes such an automatic stop device includes a method of detecting the rotation of the take-up reel shaft and a method of detecting the rotation of the rewind reel shaft, but in general, the method is advantageous for tape running characteristics such as wow and flutter. A method for detecting the rotation of a take-up reel shaft has been used, and such a method will be described below.

In a cassette-type tape recorder configured in this way, if a rewind operation is performed without a cassette installed, the drive mechanism of the tape recorder enters the rewind state, but the take-up reel shaft is stopped, so the automatic stop device is activated. The actuated drive mechanism is returned to its stopped state.

However, when playback or fast-forwarding is performed, the take-up reel shaft rotates, so the automatic stop device does not operate, and the tape recorder's drive mechanism continues to drive even though no cassette is installed. become.

Such operation not only causes wear of drive parts such as belts and pinch rollers, but also wastes valuable power in portable tape recorders that use batteries.

The present invention has been developed in view of these points, and will be described in detail below with reference to the illustrated embodiments.

In the figure, 1 is a rotation detection circuit that detects when the reel shaft (not shown) has stopped rotating, and 2 is a rotation detection circuit that repeats charging and discharging operations by the rotation detection circuit 1 while the reel shaft is rotating, so that the charging potential is below a predetermined value. , is a charging/discharging capacitor whose charging potential rises above a predetermined value when the rotation of the reel shaft stops.

3 is a transistor that is turned on when the charging potential of the charging/discharging capacitor 2 rises above a predetermined value; and 4 is a transistor that is turned on when the transistor 3 is turned on, and is turned on and stopped in accordance with the reversal operation. This is a drive control transistor that turns on the drive transistor 6 that causes the plunger 5 to perform a suction operation.

Reference numeral 7 designates a switch that is closed during playback, fast-forwarding, and rewinding operations to supply power to the aforementioned circuits, and 8 a feedback circuit provided for rapidly inverting the transistors 3, 4, and 6.

Reference numeral 9 includes a resistor 10 as a collector, a rewinding switch 11 that is closed during the rewinding operation, and an operation of a mechanism for canceling the rewinding operation.
A first transistor connected to the base of the drive control transistor 4 through a selection switch 12 for selecting non-operation and a counter switch 13 that is closed when the scale of the counter shows a predetermined value, and whose emitter is grounded.
It is a control transistor, and its base is connected to a power supply line 15 via a resistor 14 and grounded via a capacitor 16.

The collector emitter path of 17 is the capacitor 1.
a second control transistor connected in parallel to 6;
Its base is connected to the power supply line 15 via a capacitor 18 and a resistor 19, and is grounded via a resistor 20.

In this configuration, the time constant determined by the resistor 14 and capacitor 16 is set to be longer than the time during which the counter switch 13 is closed during rewinding, and the values of the capacitor 18 and resistor 19.20 are set as described above. The time constant is set to be sufficient to discharge the charge in the capacitor 16 by making the second control transistor 17 conductive.

A detection switch 21 is opened when a cassette is loaded, and is connected in parallel to the rewind switch 11, selection switch 12, and counter switch 13, which are connected in series, as shown in the figure.

The present invention is constructed and operated as described above, and its operation will now be explained.

First, the automatic stop operation when a cassette is installed and various operations are performed will be explained.

When playback, fast forwarding, and rewinding operations are performed, the operation buttons are locked, each operating state is configured, and the switch 7 is closed.

Since the reel shaft rotates while the tape is running, the charging potential of the charging/discharging capacitor 2 is kept below a predetermined value by the rotation detection circuit 1, and the transistor 3 is not turned on.

When the tape is driven and reaches the end, the rotation of the reel shaft is stopped and the charging potential of the charging/discharging capacitor 2 rises above a predetermined value.

As a result, the transistor 3 is turned on, the drive control transistor 4 and the drive transistor 6 are turned on, and the stopping plunger 5 is caused to perform a suction operation.

Therefore, the operation button is unlocked by the stopping plunger 5, and the tape recorder is brought to a stopped state.

Although the automatic stopping operation is performed as described above, the operation of canceling the rewinding operation at a predetermined position will now be described.

When the cassette is installed, the detection switch 21 is opened, and the selection switch 12 is closed to enable the mechanism for canceling the rewinding operation.

When a rewinding operation is performed in such a state, the switch 7 and the rewinding switch 11 are closed to enter the rewinding operation state, but when the power is supplied by closing the switch 7, the second control transistor 17 is turned off. is in an on state for a predetermined period of time to discharge the charge in the capacitor 16, and after the second control transistor 17 is inverted to an off state, the capacitor 16 is turned on.
is charged, and the charging potential of the capacitor 16 becomes a potential that turns on the first control transistor 9, but since the counter switch 13 is in an open state, the drive control l/run sister 4 is in an off state.

In this state, the tape is rewound and when the scale of the counter reaches a predetermined value, the counter switch 13 is closed.

As a result, the first control transistor 9 immediately turns on, turns the drive control transistor 4 and the drive transistor 6 into the on state, and causes the stop plunger 5 to perform a suction operation.

Therefore, the rewind button is unlocked by suction of the stopping plunger 5, and the tape recorder changes from the rewinding state to the stopped state, and the tape can be accurately stopped at the starting position.

Further, if the rewinding operation is performed while both the selection switch 12 and the counter switch 13 are in the closed state, the collector of the first control transistor 9 will be connected to the base of the drive control transistor 4, but the switch 7 When power is supplied by the closing of
does not turn on immediately.

Then, when the charging potential of the capacitor 16 rises to a value that turns on the first control transistor 9, the counter switch 13, which had been closed due to the unwinding of the tape during that time, becomes open, and the stop plunger 5 is sucked. It does not operate and the tape can be rewound without any problem.

The automatic stop operation and rewind release operation are performed as described above, but next we will explain the case where playback, fast forwarding, or rewinding operations are performed without a cassette installed.

When the cassette is not attached, the detection switch 21 is in a closed state as shown.

When the button is pressed in such a state and a playback, fast forwarding or rewinding operation is performed, the switch 7 is closed and the drive mechanism for each operation becomes operational.

Then, after a predetermined period of time has elapsed, that is, the second control transistor 1γ is reversed to the on state to discharge the electric charge of the capacitor 16, and the transistor 17 is reversed to the off state. When the charging potential of the capacitor 16 reaches a predetermined value, the first
Control transistor 9 is turned on.

As a result, the drive control transistor 4 and the drive transistor 6 are turned on, causing the stop plunger 5 to perform a suction operation.

Therefore, each drive operation is canceled and the tape recorder is brought to a halt, so that the drive mechanism does not perform any unnecessary operations.

As explained above, according to the present invention, even if a drive operation is performed without a cassette installed, the drive operation can be canceled, thereby reducing unnecessary wear and tear on the parts that make up the drive mechanism. Waste can be prevented.

The mechanism is simple and has a simple structure because it combines an automatic stop device that stops the tape recorder at the end of the tape and a plunger that serves as a mechanism that cancels the rewinding operation at a predetermined position. Since the detection switch is connected in parallel to the rewind switch, selection switch, and counter switch located in the operation section of the tape recorder main body, there is no need for special wiring for the detection switch from the circuit board, and assembly work is simplified. can be done easily.

[Brief explanation of the drawing]

The illustrated circuit is one embodiment of the present invention. Explanation of main drawing numbers, 1...Rotation detection circuit, 5...
... Stop plunger, 9 ... First control transistor, 11 ... Rewind switch,
12... Selection switch, 13... Counter switch, 17... Second control transistor 21... Detection switch.

Claims (1)

[Scope of utility model registration request] For a cassette tape recorder having a mechanism and an automatic stop device for canceling the rewinding operation when the scale of the counter that displays the running amount of the magnetic tape shows a predetermined value,
A plunger for unlocking the push button mechanism, a drive control transistor for driving and controlling the plunger, a rewinding switch that is closed during a rewinding operation, and a selection switch that selects whether or not the release mechanism is activated. , a counter switch that is closed when the scale of the counter indicates a predetermined value, and a collector connected to the pace of the drive control transistor through the rewind switch, selection switch, and counter switch, and an emitter a first control transistor, the first control transistor being grounded;
a capacitor connected between the base of the control transistor and ground; a second control transistor that conducts for a predetermined period of time when the power is turned on to discharge the charge in the capacitor; It consists of a detection switch connected in parallel to a rewinding switch, a selection switch, and a counter switch, and the plunger is sucked by conduction of the first control transistor after a predetermined time when the drive operation is performed without a cassette installed. A cassette type tape recorder characterized in that the drive operation is released by activating the cassette tape recorder.