JPS5839567Y2 - Accidental erasure prevention alarm device for cassette tape recorder - Google Patents

Description

[Detailed description of the invention] The present invention relates to a cassette type tape recorder that uses a cassette with a cassette equipped with a cassette that is provided with a cassette that is provided with a cassette on the rear or side end surface to determine whether or not recording is possible, and particularly relates to an alarm device to prevent erroneous erasure. .

Generally, a cassette type tape recorder is equipped with an accidental erasure prevention mechanism that controls whether or not a recording operation can be performed by detecting the presence or absence of an accidental erasure prevention claw provided on the cassette.

The accidental erasure prevention mechanism of the tape recorder, which performs a mechanical switching operation, is configured to control whether or not the recording operation button can be pressed by the displacement of a detection lever that detects the presence or absence of an accidental erasure prevention claw. This is a common feature, and according to this configuration, when the recording operation button is pressed, the user can recognize whether recording is possible or not depending on whether or not the operation button changes.

On the other hand, in a tape recorder's high-speed erasing mechanism called a dictating transcriber machine, which is used in combination with tape recorders and typewriters, the switching operation of the tape recorder is performed by the suction action of a plunger. The tape recorder is configured to control the operation of the tape recorder, and electrically prevents erroneous erasure.

Therefore, when operating the recording switch or the erasing switch, the user cannot recognize whether or not recording or erasing is possible by operating the switch.

To solve this problem, a cassette that must not be used for recording or erasing, i.e., a cassette +-f whose claw for preventing accidental erasure has been removed, is used to prevent accidental erasure, which generates an alarm when a recording or erasing operation is performed. An alarm system is used.

The present invention is intended to provide an optimal device as the above-mentioned accidental erasure prevention alarm device, and will be described in detail below with reference to the drawings.

In the figure, 1 is a movable contact that detects the presence/absence of the erroneous erasure prevention claw provided on the cassette and contacts the first contact 2 and the second contact 3 in accordance with the presence/absence of the VCH erasure prevention claw. 4
The first contact 2 is connected to a DC power source via a resistor 5.

Reference numeral 6 indicates an erase switch that is activated during a recording operation or a high-speed erase operation, 7 indicates a DC erase type magnetic head that performs an erase operation when DC power is supplied, and 8 outputs a signal to an output terminal according to a change in the input current. do.

It is an operational amplifier, one input terminal 9 is connected to the power supply via a resistor 10, and the other input terminal 11 is connected to the power supply through a resistor 12,1.
3 to the second contact 3 of the detection switch 1, and a connection point P between the disconnected resistors 12 and 13 is connected to a power source via a resistor 14.

15 is an alarm generation circuit connected to the output terminal 16 of the operational amplifier 8;
It has a function of being activated when an output signal appears on the screen and emitting an alarm sound, for example.

In such a configuration, the resistor 5 is set to have a resistance value that can supply the direct current necessary for the DC erasing magnetic head 1 to perform an erasing operation, and the resistor 13 is set to a resistance value that can supply the DC current necessary for the DC erasing magnetic head 1 to perform an erasing operation. The resistance value is set so that the head 7 supplies a small current that does not adversely affect the signals recorded on the magnetic tape.

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

The illustrated state is a case in which a cassette whose erroneous erasure prevention claw has not been removed, that is, an erasable cassette is used, and the movable contact piece 4 of the detection switch 1 is in contact with the first contact 2.

When a recording operation or a high-speed erasing operation is performed in this state, the erasing switch 6 is closed, and as a result, DC current for erasing is supplied to the DC erasing magnetic head 7 via the resistor 5, the detection switch 1, and the erasing switch 6. be done.

Therefore, the DC erasing type magnetic head 7 operates as an erasing head, and an erasing operation for recording or high-speed erasing is performed.

In this case, since the input signal of the operational amplifier 8 does not change, no output signal is output to the output terminal 16, and the alarm generating circuit 15 does not operate.

Next, a case will be described in which a cassette with the erroneous erasure prevention claw removed, that is, a cassette that cannot be erased, is used.

When such a cassette is used, the movable contact piece 4 of the detection switch 1 is in contact with the second contact 3, and when a recording operation or a high-speed erasing operation is performed in this state, the erasing switch 6 is closed. .

As a result, a DC current flows through the DC erasing magnetic head 7 via the resistors 14, 13, the detection switch 1, and the erasing switch 6, but this current is so small that it does not adversely affect the signals recorded on the magnetic tape. There isn't.

With the closing of the cut-off switch 6, the current input to the input terminal 11 of the device 8 decreases, an inverted output signal appears at the output terminal 16, and the alarm generating circuit 15 is activated.

Therefore, the user can recognize by the alarm sound emitted from the alarm generating circuit 15 that he/she is using a cassette that cannot be used for recording or high-speed erasing.

In this embodiment, the alarm means of the alarm generating circuit 15 is an alarm sound, but it may also be carried out by lighting or blinking an alarm lamp.

As explained above, the alarm device of the present invention provides an alarm when an operation for recording or high-speed erasing is performed using a cassette that cannot be used for recording or high-speed erasure, that is, a cassette from which the claw to prevent accidental erasure has been removed. Since the generating circuit is activated and issues an alarm, the user can easily recognize that he/she is using a non-erasable cassette.

In addition to using an operational amplifier as a configuration for controlling the alarm operation of the alarm generation circuit, a minute current is passed through a DC erasing magnetic head used as a head to reduce the input current to the input terminal of the operational amplifier. Since the operational amplifier is changed to perform the inversion operation, that is, the erase head is fully utilized to perform the inversion operation, the present invention has the advantage of simplifying the circuit configuration.

Furthermore, we used a detection switch that supplies erasing current to the erasing head to change the input current to the operational amplifier, so if an alarm is issued, erasing current will not flow to the erasing head. The present invention has the advantage that the alarm operation can be performed accurately without any problems.

[Brief explanation of drawings]

The illustrated circuit is an embodiment of the accidental erasure prevention alarm device of the present invention. Explanation of main figure numbers, 1...detection switch, 2...1st
Contact, 3... Second contact, 4... Movable contact piece, 6...
Erase switch, 7... DC erase type magnetic head, 8...
- Operational amplifier, 15... Alarm signal generation circuit.

Claims (1)

[Scope of utility model registration request] In a tape recorder using a cassette with a claw for preventing accidental erasure on the end surface, the presence/absence of the claw for preventing accidental erasure is provided.
a detection switch having a movable contact piece that detects the presence or absence of the erroneous erasure prevention claw and contacts a first contact and a second contact according to the presence or absence of the erroneous erasure prevention claw; and an erasure switch that is closed by a recording operation or a high-speed erasing operation. a switch, a DC erasing magnetic head to which an erasing DC current is supplied through the detection switch and the erasing switch when the movable contact piece of the detection switch is on the first contact side; one input terminal is connected to a power source; and an operational amplifier whose other input terminal is connected to the second contact of the detection switch, and an alarm generation circuit whose operation is controlled by the output signal of the operational amplifier, and whose claw for preventing accidental erasure is removable. When the erasing switch is closed in the cassette usage state, a minute current is supplied through the detection switch and the erasing switch to an extent that does not adversely affect the recording signal of the DC erasing magnetic head Vζ magnetic tape. A false erasure prevention alarm device for a cassette type tape recorder, characterized in that the output of the operational amplifier is changed by a change in the current value to the input terminal of the amplifier, thereby activating the alarm generating circuit.