JPS6131391Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a tape recorder, and particularly aims to provide a tape end detection device for a tape recorder that detects when the tape has reached the end. Explain in detail.

In the figure, 1 is the reel shaft on the supply or take-up side;
2 is a pulse signal generating circuit which generates a pulse signal in accordance with the rotation of the reel shaft 1, and 3 is a clock signal generating circuit which generates a clock signal regardless of the rotation of the reel shaft 1. A first counter 4 has an input terminal 5 to which the clock signal from the clock signal generation circuit 3 is input, and counts the number of clock signals, and a reset terminal to which the signal from the pulse signal generation circuit 2 is applied. 6 and an output terminal 7 from which an H (high) level signal is output when the count reaches a predetermined value.

A second counter 8 has an input terminal 9 to which the clock signal from the clock signal generation circuit 3 is input, and counts the number of clock signals. It has a reset terminal 11 to which a signal is applied, and an output terminal 12 to which an H level signal is output when the count reaches a predetermined value. 13 is an OR circuit that receives signals from the first counter 4 and the second counter 8; 14 has one input terminal connected to the output terminal of the OR circuit 13, and the other input terminal connected to the power supply via a resistor 15; The AND circuit 16 connected to is a switch that is closed when the tape recorder is in a pause state, and when the switch 16 is closed, the
Since the input terminal of the AND circuit 14 is grounded and becomes L (low) level, the output of the AND circuit 14 becomes L level. Reference numeral 17 denotes a control circuit which stops the tape recorder when the output signal from the AND circuit 14 is input and an H level signal is applied.

The present invention is constructed as described above, and its operation will be explained next. When the tape recorder is in a reproducing operation state and the magnetic tape is running, the switch 15 is open and the reel shaft 1 is in a rotating state. Therefore, the pulse signal generating circuit 2 outputs a pulse signal corresponding to the rotational speed of the reel shaft 1, and when the output of the pulse signal generating circuit 2 is at H level, the first
An H level signal is applied to the reset terminal 6 of the counter 4, and the reset terminal 1 of the second counter 8 is applied.
1 is applied with an L level signal inverted by an inverter 10. Conversely, when the output of the pulse signal generating circuit 2 is at L level, the first
An L level signal is applied to the reset terminal 6 of the counter 4, and the reset terminal 1 of the second counter 8 is applied.
1 is applied with an H level signal. Therefore, while the reel shaft 1 is rotating, the first counter 4 and the second counter 8 are reset alternately and periodically by the signal from the pulse signal generating circuit 2. Therefore, even if the clock signal from the clock signal generation circuit 3 is input to the input terminals 5 and 9, the first counter 4 and the second counter 8 do not perform a predetermined count operation, and the clock signal is input to the output terminals 7 and 12. An H level signal is never output. When the reel shaft 1 is rotating in this way, the output of the OR circuit 13 will never go to H level, so
The output of the AND circuit 14 also never becomes H level, and the control circuit 17 does not operate.

Therefore, the tape recorder continues to reproduce without being switched to a stopped state.

As described above, the tearing operation is performed while the tape is running.Next, the case where the tape is wound and reaches the end will be described. When the tape reaches the end after winding, the reel shaft 1 stops rotating, so that the output terminal of the pulse signal generating circuit 2 continues to receive an H level signal or an L level signal.

First, the case where the output signal of the pulse signal generating circuit 2 reaches the end at H level will be described. In this case, since an H level signal is applied to the reset terminal 6 of the first counter 4, the first counter 4 is in a reset state and does not perform a counting operation. On the other hand, since the L level signal inverted by the inverter 10 is applied to the reset terminal 11 of the second counter 8, the second counter 8 is in a state of counting the clock signal input to the input terminal 9. be. When the count number by the second counter 8 reaches a predetermined number, an H level signal is output to the output terminal 12. the result
Since the output of the OR circuit 13 becomes H level and the output of the AND circuit 14 accordingly becomes H level, the control circuit 17 to which this signal is applied becomes active and stops the tape recorder.

Next, a case will be described in which the reel shaft 1 stops rotating while an L level signal is output to the output terminal of the pulse signal generating circuit 2. When kneading, an L level signal is applied to the reset terminal 6 of the first counter 4, so it is in a counting operation state, and conversely, an H level signal inverted by the inverter 10 is applied to the reset terminal 11 of the second counter 8. It is in a reset state because it is being applied. Said first
The number of clock signals applied to the input terminal 5 of the counter 4 is counted, and when the counted number reaches a predetermined number, an H level signal is outputted to the output terminal 7.

As a result, the output of the OR circuit 13 becomes H level, and the output of the AND circuit 14 becomes H level, so the control circuit 1 to which this signal is applied
7 is activated and causes the tape recorder to stop.

The automatic stop operation is performed in the playback operation state as described above, but when the pause operation is performed in the playback operation state, the reel shaft 1 stops and the output signal of the pulse signal generation circuit 2 goes high as in the case when the end of the tape is detected. level or L level, either the first counter 4 or the second counter 8 performs a counting operation, and the output signal of the OR circuit 13 becomes H level, but in this paused state, the switch 16 is closed. Therefore, the output of the AND circuit 14 is at L level. The control circuit 17 is therefore inactive and the tape recorder is not switched to a stopped state. A capacitor 18 connected in parallel to the switch 16 serves to prevent malfunction by holding the input terminal of the AND circuit 14 at L level for a short time when the temporary stop operation is released. In this description, the case of playback operation has been explained, but the end detection operation can be similarly performed in the case of fast-forwarding or rewinding operation. In this embodiment, the device of the present invention is composed of the first counter 4, the second counter 8, the inverter 10, the OR circuit 13, the AND circuit 14, etc., but if the arithmetic and control processing is performed by a microcomputer, it can be extremely simplified. It can be configured simply. Furthermore, in this description, an automatic stopping operation in which the tape recorder is brought to a stopped state by the control circuit 17 has been described, but it may also be configured to reverse the running of the tape.

As explained above, the tape end detection device of the present invention electronically detects the end of the tape, so it is not only possible to perform the detection operation accurately and reliably, but also to count clock signals. Since the detection operation is performed by , it is possible to accurately set the time period from when the reel shaft stops rotating until the control circuit starts operating.

[Brief explanation of the drawing]

The illustrated circuit is an embodiment of the tape end detection device of the present invention. Explanation of main drawing numbers, 1...Reel axis, 2...Pulse signal generation circuit, 3...Clock signal generation circuit,
4...First counter, 8...Second counter,
13...OR circuit, 14...AND circuit, 17...
control circuit.

Claims (1)

[Scope of utility model registration request] A pulse signal generation circuit that generates a pulse signal in accordance with the rotation of the reel axis, a clock signal generation circuit that generates a clock signal regardless of the rotation of the reel axis, and a clock signal from the clock signal generation circuit is inputted. the first to count the signal with
It consists of a second counter and a control circuit controlled by a logical sum signal of the output of the first counter and the output of the second counter, and the control circuit controls the signal from the pulse signal generation circuit to reset the first counter. A tape end detection device for a tape recorder, characterized in that a signal which is an inverted signal from the pulse signal generating circuit is applied to a reset terminal of the second counter.