JPS6131392Y2 - - 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 generation circuit that generates a pulse signal in accordance with the rotation of the reel shaft 1; 3 is a clock signal generation circuit that generates a clock signal regardless of the rotation of the reel shaft 1; 4 is the clock signal generation circuit. A frequency dividing circuit 5 divides the frequency of the clock signal from the frequency dividing circuit 4, and an adjustment circuit 5 varies the frequency division ratio of the frequency dividing circuit 4.

Reference numeral 6 denotes a first counter having an input terminal 7 to which the signal frequency-divided by the frequency dividing circuit 4 is input, and counting the number of signals, to which the signal from the pulse signal generating circuit 2 is applied. It has a reset terminal 8 and an output terminal 9 from which an H (high) level signal is output when the count reaches a predetermined value. A second counter 10 has an input terminal 11 into which the signal frequency-divided by the frequency dividing circuit 4 is input, and counts the number of signals. It has a reset terminal 13 to which an inverted signal is applied, and an output terminal 14 to which an H level signal is output when the count reaches a predetermined value. 1
5 is the first counter 6 and the second counter 1
16 is an AND circuit whose one input terminal is connected to the output terminal of the OR circuit 15 and the other input terminal is connected to the power supply via a resistor 17; 18 is a tape This is a switch that is closed when the recorder is in a paused state, and when the switch 18 is closed, the
Since the input terminal of the AND circuit 16 is grounded and becomes L (low) level, the output of the AND circuit 16 becomes L level. Reference numeral 19 denotes a control circuit which stops the tape recorder when the output signal from the AND circuit 16 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 18 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,
An H level signal is applied to the reset terminal 8 of the first counter 6, and an L level signal inverted by the inverter 12 is applied to the reset terminal 13 of the second counter 10. Conversely, when the output of the pulse signal generating circuit 2 is at L level, an L level signal is applied to the reset terminal 8 of the first counter 6, and an H level signal is applied to the reset terminal 13 of the second counter 10. Ru.
Therefore, while the reel shaft 1 is rotating, the first counter 6 and the second counter 10 are reset alternately and periodically by the signal from the pulse signal generating circuit 2.

Therefore, the signal from the frequency divider circuit 4 is input to the input terminals 7 and 1.
1, the first counter 6 and the second counter 10 do not perform a predetermined count operation, and an H level signal is not output to the output terminals 9 and 14. In this way, when the reel shaft 1 is rotating, the output of the OR circuit 15 never goes to H level, so the output of the AND circuit 16 also never goes to H level, and the control circuit 19 does not operate. Therefore, the tape recorder continues to reproduce without being switched to a stopped state.

While the magnetic tape operates as described above, the case where the tape reaches the end after winding will be described next. 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 8 of the first counter 6, the first counter 6 is in a reset state and does not perform a counting operation. On the other hand, the reset terminal 13 of the second counter 10 has the L signal inverted by the inverter 12.
Since the level signal is being applied, the second counter 10 is in a state of counting the signal from the frequency divider circuit 4 that is input to the input terminal 11. When the count number by the second counter 10 reaches a predetermined number, an H level signal is output to the output terminal 14. As a result, the output of the OR circuit 15 becomes H level, and accordingly, the output of the AND circuit 16 becomes H level.
Control circuit 1 to which the signal is applied in order to reach the level
9 is activated and causes the tape recorder to stop.

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 8 of the first counter 6, so it is in a counting operation state, and on the other hand, an H level signal inverted by the inverter 12 is applied to the reset terminal 13 of the second counter 10. is being applied, so it is in a reset state. The first counter 6 counts the number of signals from the frequency dividing circuit 4 applied to the input terminal 7, and when the counted number reaches a predetermined number, an H level signal is outputted to the output terminal 9. As a result, the output of the OR circuit 15 becomes H.
At the same time, the output of the AND circuit 15 becomes H level, and the control circuit 19 to which this signal is applied becomes active, thereby stopping the tape recorder.

The automatic stop operation is performed in the playback operation state as described above, but if the pause operation is performed in the playback operation state, the reel shaft 1 will stop and the output signal of the pulse signal generation circuit 2 will go to the H level as when the end of the tape is detected. Or become L level and 1st counter 6
Either one of the first and second counters 10 performs a counting operation and the output signal of the OR circuit 15 becomes H level, but since the switch 18 is closed in this paused state, the output of the AND circuit 16 becomes L level. in a state. The control circuit 19 is therefore inactive and the tape recorder is not switched to a stopped state. A capacitor 20 connected in parallel to the switch 18 serves to prevent malfunction by holding the input terminal of the AND circuit 16 at L level for a short time when the temporary stop operation is released.

In such a circuit, the time required for the control circuit 19 to operate after the tape reaches the end depends on the counts of the first counter 6 and the second counter 10 and the period of the signal from the frequency divider circuit 4. It is determined. Therefore, by varying the frequency division ratio of the frequency dividing circuit 4 using the adjustment circuit 5, the time required for the control circuit 19 to operate can be adjusted.

The rotational speed of the reel shaft 1 not only changes during the playback operation, but also becomes faster in the fast forward or rewind state than during the playback operation, and the period of the pulse signal from the pulse signal generation circuit 2 increases accordingly. Change. Therefore, the reset period of the first counter 6 and the second counter 10 will change. By adjusting the frequency dividing ratio of the frequency dividing circuit 4 to be variable in accordance with such a reset cycle, it becomes possible to minimize the time required for the control circuit 19 to operate after the reel shaft 1 stops. , it is possible to prevent unnecessary loads from being applied to the drive mechanism of the tape recorder.

Note that although this description has been made regarding the case of a playback operation, the end detection operation can be performed similarly in the case of a fast forward or rewind operation. Further, although the automatic stopping operation in which the tape recorder is stopped by the control circuit 19 has been described, it is also possible to configure the tape recorder to reverse the running of the tape.

As explained above, since the tape end detection device of the present invention electronically detects the end of the tape, it is not only possible to perform the detection operation accurately and reliably, but also to detect the end of the tape from the clock signal generation circuit. Since an adjustment circuit is provided to vary the frequency division ratio of the frequency division circuit that divides the signal, the time required for the control circuit to operate after the reel axis stops can be adjusted to suit the operating state of the tape recorder. , the practicality of this invention is very great.

[Brief explanation of drawings]

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... Frequency division circuit, 5... Adjustment circuit, 6... First counter, 10... Second counter, 15...
OR circuit, 16...AND circuit, 19...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 that divides the frequency of the clock signal. a frequency dividing circuit; a frequency dividing circuit that divides the frequency of the clock signal from the frequency dividing circuit; a signal from the frequency dividing circuit is input and the signal is counted;
and a first circuit to which the signal from the pulse signal generation circuit and the inverted signal are respectively applied to the reset terminal.
an adjustment circuit for varying the frequency division ratio of the frequency divider circuit, comprising a counter, 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; A tape end detection device for a tape recorder, characterized in that it is provided with a tape end detection device.