JPS5817992B2 - Tape amount display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape amount display device for displaying tape usage time, tape remaining amount time, etc. in a tape recorder.

A tape amount display device in a typical tape recorder, such as a so-called tape counter that displays the amount of tape used, counts the number of rotations of a tape supply reel and thereby displays the amount of tape supplied.

However, in this case, since the winding diameter of the tape is involved, the amount of tape supplied and the number of revolutions of the supply reel do not correspond uniquely, and the amount of tape used is not accurately displayed.

Further, such a display device cannot display the remaining amount of tape.

SUMMARY OF THE INVENTION The present invention aims to provide a novel tape display device that can accurately determine the remaining amount of tape and the amount used.

Hereinafter, an example of a tape amount display device according to the present invention, particularly a display device for displaying the remaining amount of tape, will be described.

Prior to the explanation, first, the remaining tape amount t8 will be considered.

Now, as shown in FIG.
Let us now consider the case where the recording medium is wound onto the take-up reel 3 passing in front of the recording/reproducing magnetic head H.

In the same figure, 4 is a capstan, 5 is a pinch roller, and 6 is a capstan.
is a guide roller.

At this time, the total length 18 of the tape 1 wound on the supply reel 2 is π(r82 rh2) 1-□ ...... (1) 8 δ (However, r8 is The diameter of the tape wrapped in
rh is given as the pub diameter of reel 2).

On the other hand, if the running speed of the tape 10 is V, the rotation speed Ps of the supply reel 2 is Ps-□ ・・・・・・・・・・・・(2) 2πr
s And from this ■ ””−2xPs °°°°”−°−(3) And,
Looking at the rate of change of the tape winding diameter r8 over time, assuming that the tape speed V is constant, dt8 -v dPS dt 27rPs2dt ``'''''''''' (4)di Also, since the tape speed V is given by -, , (1) formula % formula % (5) Substituting formula (4) into formula (5), and for l (and v
1 dPs δ=-・-0-・・・・・・・・・(6)2π ps3
It becomes at t.

The time t8 required for the tape 1 on the supply reel 2 to run out (ie, the remaining amount of tape) is given by 18/v.

Substituting equation (4) into equation (7), we get Substituting equation (2) here, we get becomes.

Then, by further transforming this equation (8), 2πPSrh
□ becomes.

Now, in this equation (9), if we set the rotation speed Ps so that (-) < 1, then -Ps
1 t8--・□ ・・・・・・・・・・・・(10)2
dPs/dt.

Solving the differential equation of this equation 00), we get t, −YJ゛°
°−°−u (However, A is an integral constant.

Now, if t8 at r8-rll is TB, then 1. 2π A=TB・(−庚)2 ・・・・・・・・・α2.

In this case, in the time display, when t8='rB,
Just set it so that it becomes "0".

In the present invention, the remaining time t is determined by performing calculations based on the 00 formula.
It is like finding 8.

FIG. 2 shows an example of the configuration of the apparatus of the present invention.

In this case, a rotation speed detection means 7 is provided for obtaining an output signal at a level corresponding to the rotation speed PS of the reel (2).

The rotation speed detection means 7 may be configured by, for example, providing a frequency generator in connection with the rotation system of the reel 2, or
It is also possible to optically detect the rotational speed using a photodiode or the like and extract it as an electrical signal.

A multiplication circuit 32 is provided which squares the output signal corresponding to the number of rotations Ps of the wheel 20 from the detection means 7.

On the other hand, a reference signal generation circuit 33 is provided which generates an output signal corresponding to A shown in the 0 test.

Further, a division circuit 34 is provided to divide the output signal corresponding to A from the reference signal generation circuit 33 by the signal corresponding to Ps2 from the multiplication circuit 32.

In this way, a signal corresponding to t8 calculated based on the formula 01) can be obtained from the output terminal 35, so that the display means 2 for displaying the remaining time corresponding to this can be obtained.
1, the remaining time t8 of the tape can be displayed.

As mentioned above, according to the apparatus of the present invention, the remaining time t8 of the tape
Since it is calculated and displayed based on this calculation, accurate display can be performed.

In addition, in the above example, the supply side reel 20 rotation speed Ps
In this case, the remaining time t8 of the tape is detected by detecting the time t8, but if the same operation is performed for the take-up reel 3, the usage time of the tape can be detected, or both can be detected. By doing this, you can know the total amount of tape, or in other words, the recordable time of the tape.

Further, according to the above-mentioned apparatus of the present invention, measurement can be performed at any position on the tape, so that the advantages in practical use are considerable.

[Brief explanation of the drawing]

FIG. 1 is a schematic top view of a tape recorder for explaining the present invention, and FIG. 2 is a block diagram of an embodiment of the apparatus of the present invention. 1 is the tape, 2 is the supply side reel, 3 is the take-up side reel, 7
32 is a multiplication circuit, 33 is a reference signal generation circuit, and 21 is a tape amount display means.

Claims (1)

[Claims] 1. A tape reel rotation speed detection means, a reference signal generation circuit that generates an output signal according to the tape running speed, a multiplication circuit that squares the output signal of the tape reel rotation speed detection means, and the squaring circuit. and a division circuit that divides the output signal of the reference signal generation circuit by the number, the remaining time of the tape is detected by the division, and the tape display means is controlled by the detection signal. Device.