JPS6336507Y2 - - 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 as the reel shaft 1 rotates; 3 is a clock signal generation circuit that generates a clock signal; 4 is a circuit that generates a pulse signal from the pulse signal generation circuit 2 and the clock signal generation circuit 3; A first AND circuit receives the output signal as an input; 5 is an inverter for inverting the output signal from the pulse signal generating circuit 2; 6 receives the signal inverted by the inverter 5 and the signal from the clock signal generating circuit 3 as inputs; This is the second AND circuit. Reference numeral 7 denotes a switch that is closed when the tape recorder is in a pause state. When the switch 7 is closed, the input terminals of the first AND circuit 4 and the second AND circuit 6 are grounded and set to L (low) level. Therefore, the outputs of the first AND circuit 4 and the second AND circuit 6 both become L level. 8 is a first counter that has an input terminal 9 to which the output signal of the first AND circuit 4 is input and counts the number of signals; a reset terminal 10 to which the output signal from the second AND circuit 6 is applied; Count value setting circuit 11
It is provided with a preset terminal 12 and an output terminal 13 to which a signal is applied. 14 is the second AND
This counter has an input terminal 15 to which the output signal of the circuit 6 is input, and counts the number of signals. Preset terminal 17 to which the signal is applied
and an output terminal 18. 19 is the first
The OR circuit 20 which receives the signals from the counter 8 and the second counter 14 stops the tape recorder when the output signal from the OR circuit 19 is input and an H (high) level signal is applied. This is a control circuit that In such a configuration, the count value setting circuit 11 connects the output terminals 13, 1 of the first counter 8 and the second counter 14.
This serves to set the count number at which an H-level signal is output at 8.

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 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 AND circuit 4 outputs an H level signal. The second AND circuit 6 receives an L level signal inverted by the inverter 5. Conversely, when the output of the pulse signal generation circuit 2 is at L level, the first AND circuit 4 receives an L level signal, and the second AND circuit 6 receives an H level signal inverted by the inverter 5. Ru. Since a clock signal is applied from the clock signal generation circuit 3 to the first AND circuit 4 and the second AND circuit 6 at a predetermined period, while the pulse signal is being output from the pulse signal generation circuit 2, the clock signal is applied to the first AND circuit 4 and the second AND circuit 6.
The output terminals of the 1AND circuit 4 and the 2nd AND circuit 6 are H.
A level signal and an L level signal are output alternately. The output signal of the first AND circuit 4 is applied to the input terminal 9 of the first counter 8 and the reset terminal 16 of the second counter 14.
The output signal of the circuit 6 is connected to the input terminal 15 of the second counter 14 and the reset terminal 10 of the first counter 8.
, the first counter 8 and the second counter 14 are repeatedly reset while the reel shaft 1 is rotating. Therefore, the first counter 8 and the second counter 14 do not count the predetermined number, and no H level signals are output to the output terminals 13 and 18. When the reel shaft 1 is rotating in this way, the output of the OR circuit 19 never becomes H level, so the control circuit 20
does not operate, and the tape recorder continues to play.

The operations performed while the tape is running as described above are performed. Next, the case where the tape is wound and reaches the end will be described. When the tape reaches the end, the reel shaft 1 stops rotating, so that an H level signal or an L level signal is output to the output terminal of the pulse signal generating circuit 2. 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 the second AND
Since the L level signal inverted by the inverter 5 is input to the circuit 6, its output becomes L level regardless of the clock signal from the clock signal generating circuit 3. Therefore, the first counter 8 counts the number of signals input to the input terminal 9 without being reset. On the other hand, since the H level signal from the pulse signal generation circuit 2 is applied to the input terminal of the first AND circuit 4, a signal synchronized with the clock signal from the clock signal generation circuit 3 is output to its output terminal. That will happen. Applicable number
The output signal of the 1AND circuit 4 is sent to the first counter 8.
is applied to the input terminal 9 of , and its number is counted. The first counter 8 performs a counting operation, and when the count reaches a predetermined number, the output terminal 1
3, an H level signal is output. The result OR
The output of the circuit 19 becomes H level from L level,
The control circuit 20 to which the H level signal is applied becomes operational 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. In this case
Since the 1AND circuit 4 receives an L level signal, its output becomes L level regardless of the clock signal from the clock signal generating circuit 3. Therefore, the second counter 14 is not reset,
The number of signals input to the input terminal 15 is counted. On the other hand, since a signal inverted to H level by the inverter 5 is applied to the input terminal of the second AND circuit 6, a signal synchronized with the clock signal from the clock signal generation circuit 3 is output to its output terminal. It turns out. The output signal of the second AND circuit 6 is applied to the input terminal 15 of the second counter 14, and the number is counted. The second counter 14 performs a counting operation, and when the counted number reaches a predetermined number, an H level signal is outputted to the output terminal 18. As a result, the output of the OR circuit 19 changes from the L level to the H level, and the control circuit 20 to which the H level signal is applied comes into operation to stop the tape recorder.

As described above, the automatic stop operation is performed in the playback operation state, 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 to the H level as when the end of the tape is detected. Otherwise, it remains at the L level, but since the switch 7 is closed in this temporary stop state, the outputs of the first AND circuit 4 and the second AND circuit 6 both remain at the L level. Therefore, the first counter 8 and the second counter 14 will not output an H level signal, and the control circuit 20 will not malfunction. 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. Further, the time required for the control circuit 20 to operate after the reel shaft 1 stops rotating due to the end of the tape can be determined by adjusting the count value setting circuit 11 of the first counter 8 and the second counter 14. It can be done. In this embodiment, the first AND circuit 4, the second AND circuit 6, the first counter 8, and the second
Although the device of the present invention is constructed of the counter 14, the OR circuit 19, etc., it can be constructed extremely simply if the arithmetic and control processing is performed by a microcomputer. Further, in this description, an automatic stopping operation in which the tape recorder is brought to a stopped state by the control circuit 20 has been described, but it may also be configured to reverse the running of the tape.

As explained above, since the present invention electronically detects the end of the tape, the detection operation can be performed accurately and reliably, and its practicality is extremely high.

[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...1st AND circuit, 6...2nd AND circuit, 8...
...First counter, 11...Count value setting circuit, 14...Second counter, 20...Control circuit.

Claims (1)

[Scope of utility model registration request] A pulse signal generation circuit that generates a pulse signal as the reel shaft rotates, a clock signal generation circuit that generates a clock signal, and a first AND signal of the signal from the pulse signal generation circuit and the clock signal are input. a first counter that counts the number of signals as the pulse signal is generated, and a second counter that receives a signal obtained by inverting the signal from the pulse signal generating circuit and a clock signal.
It is composed of a second counter that receives an AND signal and counts the number of signals, and a control circuit that receives an OR signal of the output of the first counter and the output of the second counter. 1. A tape end detection device for a tape recorder, characterized in that during rotation, a second counter is reset by a first AND signal, and a first counter is reset by a second AND signal.