JPS5837622B2 - Song interval detection device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a track interval detection device for a tape recorder.

When playing back a music tape with a tape recorder, there are cases where it is desired to play back a desired song among a plurality of songs recorded on the tape.

In such a case, you would like to stop the tape at the beginning of the song.

For this reason, it would be convenient to be able to detect intervals between songs even in fast-forwarding or rewinding, for example.

SUMMARY OF THE INVENTION An object of the present invention is to provide a song interval detection device that can detect song gaps recorded on a tape even in fast forward or rewind conditions.

In order to detect a gap between songs, it is generally considered to determine whether or not a silent state continues for a certain period of time.

According to this method of determining whether or not a silent state continues for a certain period of time, during fast forwarding or rewinding, the tape speed differs greatly between the beginning and the end of winding, so the time width between songs differs.

For this reason, in states such as fast forwarding and rewinding, a detection method based on time cannot detect the interval between songs, and detection is possible only in a steady playback state.

In this invention, the length of the tape during which no signal continues is measured, and when the length of tape during which no signal continues reaches a certain value, it is determined that there is an interval between songs.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In this invention, the diameter of the tape winding drum at any position of the tape wound around the reel hub is R.

, the number of signals generated during one rotation of the reel hub is m,
When the minimum length of the tape for detecting between songs is l, the silence continues until the integrated value n of the signals generated while the reel hub rotates becomes 2πR.
o It is determined whether or not the interval is between songs, and when the silent state continues until the relationship of this arithmetic expression is satisfied, it is determined that it is between songs.

For this purpose, for example, a device is attached to the take-up reel (or the supply reel) that generates m signals during one rotation of the take-up reel.

An example is shown in FIG.

In this example, the disc 1 is attached to the reel shaft. A plurality of holes, m holes 2, are formed along the circumference of the disc 1, and the holes 2 turn on and off an optical switch consisting of a light emitting element 3 and a light receiving element 4, so that the reel shaft rotates once. A case is shown in which m pulses are generated from the light receiving element 4 during this period.

The pulse output from the light-receiving element 4 is amplified by an amplifier 5 as necessary, and the amplified output is waveform-shaped by a waveform shaping circuit 6, for example, as necessary, and the wave? The shaped output is supplied to the arithmetic processing unit 7, and n>ml is calculated.

m. Yo〉〉1-C, Aoyu. is 2πRo It is desirably set to about 10 to 20, for example.

Commercially available music tapes generally have short intervals between songs.

At normal playback speed, it takes about 4 seconds.

When this time is converted into tape length, it becomes approximately 18 cIrl.

Therefore, in Komata, for example, approximately half of this, 10 crI'L, is used to determine the interval between songs.

Therefore, the minimum length l for detecting between songs is l=10crrL.

For example, a microprocessor can be used as the arithmetic processing device 7, and every time a signal is supplied from the waveform shaping circuit 6, the arithmetic processing device 7 is caused to perform an interrupt operation to calculate n>”1.

2πRO On the other hand, the reproducing head 9 is brought into contact with the tape 8 to reproduce the signal recorded on the tape 78.

For this reason, it is preferable to configure the playback head 9 so that it can come into contact with the tape 8 as necessary even in fast forward or rewind conditions.

The signal reproduced by the reproducing head 9 is amplified by a reproducing amplifier 10, shaped into a pulse waveform by a waveform shaping circuit 11, and supplied to the arithmetic processing unit 7.

Therefore, each time a pulse based on this audio signal is supplied to the arithmetic processing unit 7, the integrated value n of the signals generated during one rotation of the reel shaft is reset, and as long as the audio signal exists, the value of n remains constant. Prevent it from being accumulated.

FIG. 2 shows a more detailed embodiment centered on the arithmetic processing unit 7.

In the figure, 12 is a signal source of a signal obtained during one rotation of the reel shaft.

The output signal of this signal source 12 is supplied to a waveform shaping circuit 13.

The waveform shaping circuit 13 can use, for example, a D-type flip-flop, reads the output signal of the signal source 12, and sends the read data to the interrupt terminal 14 of the arithmetic processing unit 7 and the input terminal 1.
Give to 5.

From the output terminal 16 of the arithmetic processing unit 7, the function 2πR of n>
o A reset pulse is issued every time the calculation is completed, and this reset pulse is supplied to the reset terminal R of the D-type flip-flop constituting the waveform shaping circuit 13.

Therefore, as shown in FIG. 3, every time the signal Pa from the signal source 12 rises, the output pb of the waveform shaping circuit 13 also rises.

For this purpose, it is assumed that the D-type flip 7 is driven by a high-speed clock pulse whose frequency is sufficiently higher than that of the signal Pa.

Signal pb? The arithmetic processing unit 7 is placed in an interrupt state by the rising edge of m1, stops other processing operations, and calculates n> by 2πR.
o Do it.

When this calculation is completed after a time τ from the rising time t1, a reset signal Pc is output from the output terminal 16 to reset the waveform shaping circuit 13, and at the next rise of the signal Pa, the waveform shaping circuit 13 is set and the next calculation is performed. let

On the other hand, the audio signal reproduced by the reproduction head 9 is supplied to a waveform shaping circuit 11 through an amplifier 10.

This waveform shaping circuit 11 can be composed of, for example, a voltage comparator 17 and a D-type flip-flop 18.

The voltage comparator 17 can be an operational amplifier, which applies, for example, a positive polarity setting voltage to the inverting input terminal of the operational amplifier 170, and applies an audio signal to the non-inverting input terminal.

In this way, the rectangular wave Pe shown in FIG. 4B is outputted from the operational amplifier 17 every time the audio signal Pd rises to the set voltage as shown in FIG. 4A.

The D-type flip-flop 18 is set by the rise of this rectangular wave Pe, and outputs the rHJ logic signal Pf at its output.

This logic output Pf is supplied to the input terminal 20 of the arithmetic processing device 70 m1 to stop the calculation of n, and also to
o Reset the value.

At the end of this process, a reset signal Pg is sent to the output terminal 19.
This reset signal is applied to the reset terminal R of the D-type flip-flop 18 to reset it.

Therefore, when the audio signal is no longer input, n continues to be integrated until finally ml reaches a state that satisfies n, so 2πR
o, the arithmetic processing unit 7 outputs a signal to the interface 21, and for example, the drive of the tape recorder 22 is stopped.

As is well-known, the arithmetic processing device 7 can be constructed of a calculation section 7a, a memory 7b, and a timer/counter 7c, and arithmetic processing is performed according to a program stored in the memory 7b.

m1 In the above, the arithmetic expression is n冫, but it is exactly 2πRo. ml ni・冫.

Calculated as (RO + Nh) 6 and 1゛ In this formula, N is the number of rotations of the reel from the position where the radius of the tape winding drum was measured, and h is the tape thickness.

(2) The number of revolutions N of the reel can be obtained by dividing the signal from the signal source 12 by one frequency m, and the tape thickness h can be set in advance in the memory b.

According to this formula, the diameter RO of the tape winding drum is successively corrected according to the tape feed amount, so that, for example, the diameter R of the tape winding drum at the winding start position.

If it is measured in the constant speed feed state during playback, the diameter R of the tape winding drum will remain constant even after switching to the fast feed state.

is corrected, so it can be detected accurately even between songs near the end of the volume.

As explained above, according to the present invention, the length of the tape in which no signal continues is measured, and the interval between songs is detected when the tape length in the no-signal state exceeds a predetermined length. It is possible to detect gaps between songs even in the current state.

In the above description, an optical switch is used as a means for generating m signals during one rotation of the reel, but it will be easily understood that other magnetic detection means or the like may also be used.

Moreover, although it has been explained above that the means for generating m signals is attached to either the take-up reel or the supply reel, it may be attached to both.

In this way, when signal generating means are installed on both the take-up and supply reels, it is also possible to determine whether the tape is being fast-forwarded or rewound based on the remaining polarity by calculating the calculation results obtained from both. I can make you do it.

[Brief explanation of drawings]

FIG. 1 is a system diagram for explaining the basic structure of this invention,
FIG. 2 is a system diagram showing an embodiment of the invention, and FIGS. 3 and 4 are waveform diagrams for explaining the operation of the invention. 1: Means for generating m signals during one rotation of the reel shaft; 7: . Arithmetic processing unit.

Claims (1)

[Claims] 1 The radius of the tape winding drum at any position of the tape wound on the reel hub is Ro, the number of signals generated during one revolution of the hub is m, and the minimum length of the tape for detecting between songs. length 1
When the integrated value n of the signals generated while the reel hub rotates is n > ml 2Ro, 6 or 1 silent state continues <7゛ No 7゛ is determined, and the silent state is the relationship of the above calculation formula. A song interval detection device that determines that it is a song interval when the song continues until the condition is satisfied.