JPS5828669B2 - Magnetic tape remaining time display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic tape remaining amount time display device, and more particularly to a magnetic recording/reproducing device having a tape supply reel and a take-up reel. The remaining amount of time on the magnetic tape is displayed on the indicator by utilizing the fact that the amount of time remaining on the magnetic tape is proportional to the remaining amount of time on the magnetic tape.

Conventionally, magnetic recording and playback devices have been equipped with mechanical counters or electronic counters that count the distance traveled by the magnetic tape and use this travel count value as a guide to calculate the remaining amount of magnetic tape. There is.

A mechanical counter consists of a character wheel and a counter pulley that moves the character wheel.The counter pulley is connected to a take-up reel stand or a supply reel stand with a rubber belt.
A number proportional to the number of rotations of the reel stand is displayed on the counter.

The electronic counter is configured to electronically count pulses corresponding to the rotation of the reel stand and display this count value numerically. The tape position during recording and playback is indicated by the number of rotations of the reel stand, and the number displayed on the counter does not directly represent the length of the magnetic tape.

Therefore, in order to know the remaining time of a magnetic tape, first measure the total running time and total running count value of the magnetic tape, then calculate the total running count value - the displayed count value, the total running count value It was not possible to know the remaining amount of time on a magnetic tape without performing a complicated calculation of running time.

Furthermore, with conventional devices, it is necessary to reset the counter to zero at the head position of the magnetic tape, which is cumbersome to operate.
This has the disadvantage that it becomes impossible to calculate the remaining amount of time if a zero return operation is performed by mistake, or if the magnetic tape is replaced with another magnetic tape midway through, or if it is used with the back side.

Therefore, the object of the present invention is to immediately, without complicated calculations, be able to perform any use of magnetic tape.
It is an object of the present invention to provide a magnetic tape remaining amount time display device that can accurately determine the remaining amount of magnetic tape during recording or reproduction.

In order to achieve such an object, the magnetic tape remaining amount time display device according to the present invention extracts a pulse signal proportional to the number of rotations of a magnetic tape supply reel or take-up reel from a reel rotation period detector, and extracts the pulse signal from a reel rotation period detector. The signal is input to a DC converter that converts it into a DC signal corresponding to the period, and the output of the DC converter drives an indicator to determine the remaining time of the magnetic tape.

Hereinafter, the magnetic tape remaining amount time display device according to the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a state diagram showing the relationship among a pinch roller, a capstan, and a magnetic tape during play (recording or playback) in a magnetic recording/playback apparatus for explaining the present invention in detail.

In FIG. 1, when a play operation button (not shown) is pressed, a magnetic tape 4 wound on a tape supply reel 1 is guided by a tape guide roller 5 to a recording/playback head section 8, and rotates at a constant speed. The magnetic tape 4 is pulled out at a constant speed in the right direction by being sandwiched between the capstan 6 and the pinch roller 7, and the direction of the winding force is adjusted to smoothly wind the pulled out magnetic tape 4. The tape is wound onto the tape take-up reel 2 to which a light rotational force is applied by the reel drive shaft 3b.

The tape supply reel 1 is provided with a reel drive shaft 3a to ensure stable contact between the recording/playback head section 8 and the magnetic tape 4.
As a result, a light rotational force is applied in the opposite direction to the running direction of the magnetic tape 4 to provide back tension to the magnetic tape.

In this way, at a certain point when the magnetic tape 4 being recorded (or played back) is being wound from the tape supply reel 171 to the tape take-up reel 2, the tape supply reel 1
Assuming that the remaining magnetic tape winding diameter is r (to) and the running speed of the magnetic tape is V (m7 minutes), the circumference of the outermost magnetic tape of the magnetic tape winding on tape supply reel 1 is L ( ml
is L=2πr(rnl), and in order for a magnetic tape of this length to run, the number of rotations n of the tape reel 1 is: 1+1-'i, -277(r.p.m).

Normally, the magnetic tape running speed V (m 7 minutes) is kept constant1 ■, so the number of revolutions n is n = -X K (where = 7).
7) The remaining amount of magnetic tape on the tape supply reel 1 changes in inverse proportion to the winding diameter r.

Similarly, on the take-up reel side, the relationship between the number of revolutions of the tape take-up reel 2 and the winding diameter of the remaining amount of magnetic tape remaining on the tape supply reel 1 can be easily derived.

It can be seen that during recording (or playback), the number of revolutions of the tape take-up reel 2 and the remaining amount of magnetic tape are directly proportional.

As mentioned above, the relationship between the remaining amount of magnetic tape and the rotational speed of the tape supply reel or tape take-up reel is that if the magnetic tape running speed is constant, the relationship between the remaining amount of magnetic tape and the rotational speed of the tape supply reel or tape take-up reel is It is equivalent even if it is replaced by a relationship.

Since the running speed of the magnetic tape in commonly used magnetic recording and playback devices is kept constant, the remaining time of the magnetic tape during recording or playback is inversely proportional to the number of rotations of the tape supply reel and directly proportional to the number of rotations of the take-up reel. Then it can be expressed in other words.

Such a relationship is shown in a graph in FIG.

FIG. 2a shows the relationship between the tape supply reel and the remaining amount of magnetic tape during recording or playback, and FIG. 2A shows the relationship between the tape take-up reel and the remaining amount of magnetic tape during recording or playback.

In Figure 2a, when there is a large amount of magnetic tape remaining, the rotation speed of the supply reel is small, and as the tape is wound onto the take-up reel, the rotation speed increases, and when the remaining amount of magnetic tape runs out, the rotation speed of the tape supply reel is small. The rotation speed becomes zero.

Next, in FIG. 2, when there is a large amount of magnetic tape remaining, the number of rotations of the take-up reel is high, and as the magnetic tape is wound up, the number of rotations of the take-up reel decreases.

The number of rotations of the take-up reel when the remaining amount of magnetic tape becomes zero varies depending on the type of stop mechanism of the magnetic recording/playback device.

For magnetic recording and playback devices that are designed to stop the reel rotation, such as those that stop the drive motor or lock the rotation of the capstan when the remaining amount of magnetic tape reaches zero, the curve shown in Figure 2 is used. As shown in 1, the number of rotations of the take-up reel becomes zero.

However, in a reel-to-reel type device that does not have such a function, as shown in curve 2 in Figure 2, even when the remaining amount of magnetic tape reaches zero, the rotational speed of the take-up reel remains unchanged from the take-up reel drive shaft. It continues to rotate at the rotation speed.

This is because, as described above, rotational force is applied to the take-up reel drive shaft in order to smoothly wind the magnetic tape.

Therefore, in a magnetic recording/playback device where the take-up reel continues to rotate even when the remaining amount of magnetic tape is exhausted, the proportional relationship between the remaining amount of magnetic tape and the number of rotations of the take-up reel is the remaining amount of magnetic tape. It collapses when the magnetic tape reaches zero, but since the remaining amount of magnetic tape has already reached zero, this is not a problem.

By using the relationship between the number of rotations of the tape supply reel or take-up reel and the remaining amount of magnetic tape as described above, it is possible to immediately know the remaining amount of magnetic tape time without performing complicated calculations.

FIG. 3 is a block diagram showing one embodiment of the present invention, which can be roughly divided into a reel rotation period detector 9 that magnetically or optically extracts a pulse signal proportional to the number of rotations of a magnetic tape supply reel. , a DC converter 16 that converts the pulse signal output of the reel rotation period detector 9 into a DC signal corresponding to the pulse signal period, and an indicator 11 driven by the output of the DC converter 16. ing.

The DC converter 16 receives the edge detector 10 which detects the rising and falling portions of the output pulse signal of the reel rotation period detector 9, and receives the rising and falling detection outputs of the edge detector 10, respectively, and performs each detection. First and second constant current integrators 11 and 12 that perform constant current integration of the period of the output and convert it into a sawtooth wave signal, and first and second constant current integrators 1L12.
an envelope circuit 13 that takes out the synthesized outer edge signal of the output of the envelope circuit 13, a smoothing circuit 14 that smooths the sawtooth wave output from the envelope circuit 13 and converts it into DC, and a smoothing circuit 1
The amplifier 15 has the function of amplifying the output of the magnetic tape 4, adjusting the gain, and setting the width of the remaining magnetic tape time display.

The amplifier 15 is an amplifier that directly amplifies the output of the smoothing circuit 14 when the reel rotation period detector is attached to the tape supply reel side.

Hereinafter, the operation when the reel rotation period detector is attached to the tape supply IJ-le side will be explained using the waveform diagram shown in FIG.

When the magnetic tape starts running (recording or reproducing), a pulse signal P1 proportional to the rotation period of the magnetic tape supply reel is generated.
is taken out from the reel rotation period detector 9.

When this pulse signal P1 is input to the edge detector 10, the pulse signal P1 is divided into a rising signal P2 and a falling signal P3.
is output from the edge detector as

The rising signal P2 is converted into a first sawtooth signal P4 by the first constant current integrator 11, and is supplied to the input side of one of the two signals of the envelope circuit 13, and the falling signal P3 is converted to the first sawtooth signal P4 by the first constant current integrator 11. It is converted into a second sawtooth wave signal P5 by the constant current integrator 12, and is supplied to the other input side of the envelope circuit 13.

The envelope circuit 13 receives first and second sawtooth wave signals P4.
．． P6 is output as the outer edge signal synthesized with P5, and this output signal P6 is converted into a DC signal P7 in the smoothing circuit 14.

The DC signal P7 is amplified by an amplifier 15 having a gain adjustment function, and then used as a drive signal source for the indicator 17.
The remaining amount of magnetic tape during recording or playback is displayed on the indicator 17 in time.

As shown in FIG. 5, an example of the display method, the indicator 17 has a scale that distinguishes C-601C-90, Cl2O, and the type of tape winding, so that the remaining time on the magnetic tape can be accurately and immediately known. It is made so that you can.

More specifically, a pulse signal P proportional to the rotation speed of the tape supply reel taken out from the reel rotation period detector
1 has a pulse on-off repetition period of 1:1 and is taken out from a tape supply reel stand provided on the output side, that is, on the output side of the part that performs the clutch action, and is further supplied with the pulse signal P1 of 1:1. The double-edged edges of the rising and falling portions are detected and supplied to first and second constant current integrators to generate first and second sawtooth wave signals.

In this way, the rotation of the tape supply reel is converted into a pulse signal with an on-off repetition period of 1:1, and the rising and falling edges of this pulse signal P1 are further detected.

This allows the time constants of the first and second constant current integrators to be exactly the same, and also allows the smoothing circuit to convert the sawtooth wave signal, which is the output signal of the subsequent envelope circuit, into a DC signal. This has the effect of reducing the load on capacitors, etc., and at the same time provides a DC signal that accurately corresponds to the number of rotations of the tape supply reel, allowing you to immediately and accurately know the remaining amount of magnetic tape through the display. It has the excellent effect of being able to

FIG. 6 shows another embodiment of the present invention, in which the pulse signal proportional to the supply reel rotation speed output from the reel rotation period detector 9 attached to the tape supply reel side is a DC signal corresponding to the pulse period. The pulse period is converted into a DC signal by the DC converter 18, and the signal is converted into a DC signal by three series of amplifiers 15.
supplied to

The output of each amplifier 15 is the level setter 1 of each series.
9, 20. By 21, relay 22 indicates "50 minutes remaining"
The relay 23 operates at level ■1 corresponding to ``1'' and lights up the lamp 28 by its contact 25, illuminating the indicator 31 indicating ``50 minutes remaining'', and the relay 23 indicates ``40 minutes remaining''. When the relay 24 operates at level ■2, the lamp 29 is lit by the contact 26, and the indicator 32 indicating "40 minutes remaining" is activated, and the relay 24 operates at level ■3 corresponding to "30 minutes remaining". The lamp 3 is actuated by its contacts 27.
0 lights up, and the levels are set to Vl + V2 + V3, respectively, so that the indicator 33 of "30 minutes remaining" is illuminated.

In the magnetic tape remaining amount time display device configured as described above, when a magnetic tape with a tape winding of 60 minutes is played back from the beginning position of the tape, the message "Remaining amount 50" is displayed after 10 minutes have elapsed.
The "minutes" indicator is illuminated by a lamp, indicating that there are 50 minutes remaining on the magnetic tape.

Similarly, indicators for ``40 minutes remaining'' and ``30 minutes remaining'' are illuminated by lamps so that the remaining time on the magnetic tape can be immediately known.

Of course, the level can be varied using the level setting device, so by setting the necessary level according to the usage situation, the indicator for the required remaining amount time can be activated.

By doing so, it is possible to immediately know the remaining amount of time on the magnetic tape, and at the same time, it is possible to easily know the elapsed time of recording or playback by blinking the lamp without using a timer.

As explained above, the magnetic tape remaining amount time display device according to the present invention converts a pulse signal proportional to the rotational speed of the magnetic tape supply reel or take-up reel into a DC signal corresponding to the period of the pulse signal. Since the indicator is driven by a DC signal and the remaining time of the magnetic tape is known during recording or playback, it is possible to change from playing the front side to playing the back side during any use of the magnetic tape. However, unlike conventional mechanical counters, it does not require a return-to-zero operation, nor does it require complicated calculations to immediately and accurately determine the remaining amount of magnetic tape remaining, making it superior in terms of operability and functionality. It has a great effect.

[Brief explanation of drawings]

FIG. 1 is a state diagram showing the states of the pinch roller, capstan, and magnetic tape during play (recording or playback) in a magnetic recording/playback device for detailed explanation of the present invention;
Figure a is a graph showing the relationship between the number of rotations of the tape supply reel and the remaining amount of magnetic tape, the same figure is a graph showing the number of rotations of the tape take-up reel and the remaining amount of magnetic tape, and Figure 3 shows an embodiment according to the present invention. A block diagram, FIG. 4 is a waveform diagram showing the waveforms of each part of the embodiment shown in FIG. 3, FIG. 5 is a diagram showing an example of the display method of the indicator, and FIG. 6 is another embodiment according to the present invention. FIG. 1... Tape supply reel, 2... Tape take-up reel, 3a... Tape supply reel drive shaft, 3b... Tape take-up reel drive shaft, 4...
... Magnetic tape, 5 ... Tape guide roller, 6 ... Capstan, 7 ... Pinch roller, 8 ... Recording and playback head section. , 9...
... Reel rotation period detector, 10 ... Edge detector, lL12 ... Constant current integrator, 13.
... Envelope circuit, 14 ... Smoothing circuit, 15 ... Amplifier, 16 ... DC converter, 17 ... Indicator, 18. ...Pulse period DC converter, 19,20゜21...Level setter, 22,23.24...Relay 2
5, 26, 27...Relay contact, 28°29.
30...Lamp, 31.32.33...
·display.

Claims (1)

[Claims] 1. A reel rotation period detector that sends out a pulse signal proportional to the reel rotation speed of the magnetic tape supply reel or take-up reel, and converting the pulse signal output of the reel rotation period detector into a DC signal corresponding to the pulse signal period. The DC converter includes a DC converter and an indicator driven by the output of the DC converter. first and second constant current integrators that convert rising and falling detection outputs of the detector into sawtooth wave signals, respectively; and an outer edge signal that is a composite of the two outputs of the first and second constant current integrators. 1. A magnetic tape remaining amount time display device comprising an envelope circuit for taking out the signal, and a smoothing circuit for smoothing the output of the envelope circuit and converting it into direct current.