JPS6051185B2 - Tape remaining amount display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape remaining amount display method, which uses the cycle or rotational speed of the supply side reel disk and the tape reel hub diameter, and can be used even if tape reels with different hub diameters are used. It is an object of the present invention to provide a system that can accurately display the remaining amount of tape on a supply side reel disk according to the respective values.

For video cassettes, as shown in the table below, NTSC type T-120 (numbers indicate tape usable time (in minutes))
, T-9O, T-6O, T-3O, T-2O, PAL type E-24O9E-18O9E-12O, E-6
There are many types of O, E-3O, E-2, and on the other hand, the reel hub diameter is 26m77L) 62TWL.
There are different types.

C φ26 (Ni = 13) φ62 (Ni 231) System NTSC System E-240 (thin tape) PAL system In this way, video cassettes are different from general audio cassettes, as they use ones with different hub diameters.
When displaying the remaining time of a tape, it cannot be done in the same way as the remaining time of an audio tape recorder, and it would be convenient if the remaining amount could be displayed accurately even if cassettes with different hub diameters are used.

Furthermore, the user may unconsciously use the reel hub diameter of the cassette without checking the type, and it would be convenient if the type of reel hub diameter being used could be easily determined at a glance. The present invention has been made in view of the above requirements, and one embodiment thereof will be described below with reference to the drawings.

As mentioned above, there are two types of reel hub diameters, so if you simply use only the cycle of the supply side reel disk or the cycle of the take-up side reel disk, the hub diameter will change depending on the tape winding diameter of the reel. Although it is not possible to determine the average cycle of the corresponding hub diameter, it is not possible to distinguish which hub diameter it is, but it is possible to detect the sum of the cycle of the reel disc on the supply side and the cycle of the reel disc on the take-up side. By determining whether it is large or small with respect to a certain threshold, it is possible to detect the average period according to the size of the hub diameter regardless of the size of the tape winding diameter, and to determine the type of hub diameter. Further, the remaining tape time can be displayed using a calculator based on the determined type of hub diameter and the period of the supply side reel disk. Here, when we actually calculate the cycle of the reel disk and the remaining tape time using the formula, the total length of the tape is the length of the tape wound on the take-up reel after LAt seconds, the supply side reel after Lt seconds. amount of tape remaining in
L'-tape running speed
V Tape thickness H Tape outermost radius when not pulled out
The tape winding radius R of the supply reel after Rt seconds, . Tape winding radius of the take-up reel after t seconds RT Period of the supply reel disk Fs
If the period of the take-up reel disk is 1, the FT reel hub radius is 1, then for the supply reel, and similarly for the take-up reel.

Therefore, the sum F of the period F of the supply side reel disk and the period FT of the take-up side reel disk is as follows. On the other hand, regarding the supply side reel, the remaining amount time t'' of the supply side reel is as follows.If the reel hub diameter r and the period Fs of the supply side reel disk are given, the remaining amount time t'' of the supply side reel is calculated. can.

FIG. 1 shows a block system diagram for explaining one embodiment of the tape remaining amount display method according to the present invention, and shows that it is possible to obtain the above-mentioned type of reel hub diameter r and tape remaining amount time t'' of the supply reel. Show the device that can do it.

In the figure, 1 is a rotation detector for the supply reel, and 2 is a rotation detector for the take-up reel, each of which is configured to be able to extract, for example, 48 pulses per revolution of the reel disk using a photointerrupter or the like. It is said that The pulses from the rotation detector 1 are supplied to a period counter 3, and the period counter 3 counts clock pulses of a constant frequency from the oscillator 4 until the number of pulses from the rotation detector 1 reaches a preset number. That is, for example, if the number of pulses from detector 1 is 4
If the clock pulses from the oscillator 4 are counted until the clock pulses reach 8, the count value will be a value proportional to the time required for one rotation of the reel disk, and the output of the counter 3 will be a signal corresponding to the period of the reel disk. Become. The signal from the counter 3 is supplied to a multiplier 5, where the steady tape running speed (33.35 Tm/Sec for NTSC system. 39T1r1n/Sec), and as a result, the multiplier 5 outputs a signal having a level corresponding to the period F of the supply reel disk during steady tape running (which can be substantially regarded as the period f$). ) is extracted. The same is true for one reel disk on the take-up side, and the output of the cycle counter 7 is multiplied by a constant corresponding to the steady running speed of the tape in a multiplier 8. A signal having a level corresponding to the FT (substantially can be considered as a periodic FT) is extracted. The period F from the multiplier 5 and the period FT from the multiplier 8 are added by the adder 9 to obtain the period (f$j+FT), and the above equation (1) becomes . can get. Output of adder 9 (Fs
+FT) is supplied to a comparator 10, where a threshold value F, which is preset based on the type of cassette with different hub diameters, is supplied to a comparator 10.
=12.1 sec (for NTSC system) or threshold value F=
17.2 sec (in the case of PALj system), and if it is below the threshold, the cassette with a hub radius of r = 13 (T-90, T-120 in Fig. 2 (NTSC system), T-90 in Fig. 3 (PAL j system), E-120, E-180, E in
-240), if it is above the threshold, r=31W! ! A cassette with a hub radius of L (T in Figure 2 (NTSC system)
-20, T-30, T-601 (E-20, E-30, E-60) in Figure 3 (PAL system).

By determining these two types, predetermined signals are respectively extracted and displayed on the cassette display 11 to indicate the type of each cassette, while being supplied to the tape remaining time calculator 12 together with the output Fs of the multiplier 5. In the tape remaining time calculation unit 12, the period Fs which is the output of the multiplier 5 and the output of the comparator 10 (
The hub radius r) is input, and the calculation according to the above equation (2) is performed.

That is, in formula (2), rice? Calculation is performed with T and T as constants and F and 2 as variables to calculate the remaining tape time t''.The output of the calculator 12 is sent to the remaining tape time display 14 via the display drive circuit supplied and the remaining tape time is displayed.In this way, the hub diameter of the reel being used, that is, the type of cassette, can be easily confirmed at a glance.
Furthermore, even if cassettes with different reel hub diameters are used, the remaining tape time corresponding to each cassette can be accurately displayed based on the hub diameter value and the period of the supply reel. Although the period counters 3 and 7 and the multipliers 5 and 8 are provided separately for both the supply side reel and the take-up side reel, in reality, a counter memory or the like is used to combine the period counter and the multiplier. It is said that

In addition, instead of using the tape remaining time calculator 12, for example, a comparator circuit provided with a group of comparators each having a threshold level divided into one level, and a tape remaining amount time indicator are used, and the multiplier 5
The output of the comparator 10 may be supplied with the output of the comparator 10, and the levels thereof may be compared by a group of comparators of the comparison circuit, and the remaining tape time may be displayed on each element of the display divided into 1 level. .

However, this method has a lower accuracy in displaying display time than the method shown in FIG. Furthermore, the method of the present invention can be applied not only to video cassettes but also to audio cassettes or reel-to-reel types.

Furthermore, although the above embodiment is configured to detect the period of the reel disk, it may also be configured to detect the reciprocal of the period, that is, the number of revolutions.

As described above, the tape remaining amount display method according to the present invention detects the period or number of rotations of the tape reel disk on the supply side and take-up side, respectively, and adds the period or number of rotations of both reel disks. The added value is compared with a threshold value that is set based on the type of tape reel with a different hub diameter to determine the hub diameter of the tape reel in use. Even if you unconsciously attach a tape reel without checking the type of tape reel, the hub diameter can be automatically determined and the remaining amount of tape can be displayed. In particular, the hub diameter can be relatively determined from the outside of a video cassette. This is useful when using difficult-to-use cassettes, and it also calculates and displays the remaining tape time using variables such as the periodicity and rotational speed, and constants such as tape running speed, tape thickness, and hub diameter. Because of this, it has features such as being able to easily check the remaining amount of tape with an accurate value.

[Brief explanation of drawings]

Fig. 1 is a block system diagram for explaining one embodiment of the method of the present invention, and Figs. 2 and 3 show the usable time of the tape and the cycle of both reel disks in the 5N'V8)C system and the PAL system, respectively. It is a figure showing the relationship with sum. 1... Rotation detector of supply side reel, 2...
...Rotation detector of the winding side reel, 3, 7... Period counter O, 4... Oscillator, 5, 8...
... Multiplier, 6 ... Tape speed setting device, 9 ...
...Adder, 10...Comparator, 12...
. . . Tape remaining amount time calculator, 14 . . . Tape remaining amount time indicator.

Claims (1)

[Scope of Claims] 1. The period or number of rotations of the reel disks of the supply tape reel and take-up tape reel having the same hub diameter that are rotating during tape running are detected, and It is used by adding the period or number of revolutions of the reel disk of the tape reel on the take-up side and comparing whether the added value is larger or smaller than a threshold value set in advance based on the type of tape reel with a different hub diameter. The hub diameter of the tape reel inside is determined, and the remaining amount of tape on the supply tape reel is displayed based on the period or number of revolutions of the reel disk of the supply tape reel and the determined hub diameter. Tape remaining amount display method. 2. When displaying the remaining amount of tape from the cycle or rotation speed of the reel disk of the tape reel and the hub diameter, the variables of the cycle or rotation speed of the reel disk of the supply side tape reel, the tape running speed, and the tape thickness are used. , and the constant of the hub diameter to calculate and display the remaining tape amount time.