JPS6051184B2 - Cassette tape remaining time display method - Google Patents

Description

Detailed Description of the Invention The present invention can display the remaining time of a cassette tape by simply detecting the rotation period (rotation speed) of one reel, regardless of the thickness of the tape, and even when the cassette tape is partially wound. The present invention relates to a method for displaying the remaining amount of time on a cassette tape, which can be displayed with high precision even when the time is left on a cassette tape.

For example, when recording on a cassette tape, if it is possible to know the remaining time on the cassette tape, it is possible to prevent recording errors such as reaching the end of the tape during recording.

For this reason, general cassette tapes are equipped with a mechanical tape counter that counts the number of rotations of the tape reel, and a method is used to predict the remaining amount based on the count value of this tape counter. There is. however,
Since the above-mentioned tape counter simply adds up the number of revolutions of the tape reel, the winding diameter changes greatly between the start and end of winding the magnetic tape onto the reel, and the actual running distance of the magnetic tape A nonlinear relationship arises between the value of the tape counter and the count value of the tape counter. As a result, it is extremely difficult to predict the remaining amount of time from the count value of the tape counter, and it is almost impossible for the general public to predict the remaining amount of time. Winding can be used to solve this problem.

Here, the number of turns N of the magnetic tape wound on the supply reel at the time when the magnetic tape has been fed n rotations from the time of reset at a certain point in time is expressed by the following equation.

However, Rs is the radius of the outer magnetic tape at the time of reset. Therefore, by substituting equation (4) into equation (3), the length of the magnetic tape left on the supply reel can be calculated as
becomes.

When the magnetic tape is traveling in the X direction at a constant speed VO, the remaining time t is expressed by the following equation. Here, Mo? =A,t=B,d? (R52-RO2)=C
When expressed as , it becomes.

On the other hand, the rotation speed ■5 of the supply reel is Represented as iA.

Rotational speed of the supply reel immediately after performing the reset operation ■
Since the thickness d of the magnetic tape is extremely thin (approximately 18p or less), SR can be regarded as 2An<B, and can be expressed as 2An<B.

Therefore, by knowing the rotational speed (R) of the supply reel immediately after reset, the radius Rs can be determined from the following equation.
Further, A at any rotation speed n is given by equation (8).

Therefore, the thickness d of the magnetic tape is determined by equations (9) and (11) and the above A=? It becomes more.

Therefore, calculate the rotation speed ■SR of the supply reel immediately after reset (for one rotation), and then calculate the rotation speed ■9 of the supply reel in the next rotation (second rotation after reset) and the rotation speed n.
Therefore, the thickness d of the magnetic tape can be immediately determined. As described above, A, B, and C mentioned above are tape speeds V that are known in advance.

, radius R of the hub. and radius RS found immediately after reset
1 tape thickness d can be treated as a constant, and there is no need to externally select and set the type of tape, that is, the thickness of the tape. Therefore, from the above equation (2), simply finding the rotation speed n of the supply reel from the time of reset,
Using the constants A, B, and C described above, it is possible to accurately display the remaining time even for a tape that is partially wound.

Next, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing an embodiment of the cassette tape running time display method according to the present invention.

In the same figure, 1 is a supply side reel, 2 is a take-up side reel,
3 is a magnetic tape, 4a and 4b are guides, 5 is a cassette tape, 6 is a reel rotating shaft on the supply side, 7 is a rotating body attached to this reel rotating shaft 6, and marks on this rotating body 8 are magnetically and optically , or a rotation detector consisting of a detection element 9 that mechanically detects and outputs a rotation detection pulse and a signal representing the rotation direction, and the period of this rotation detection pulse is directly proportional to the rotation period of the supply reel 1. be. 1
0 is a rotation period detection unit that detects the rotation period by inputting this rotation detection pulse, 11 is a counter unit that counts the rotation detection pulse while adding or subtracting it in accordance with the rotation direction signal, and 12 is a count value of the counter 11. 13 is a calculation unit that calculates the remaining (remaining amount) running time t of the magnetic tape according to the above equation (7); 14 is provided with a movable contact 14a and fixed contacts 14b and 14c;
When the movable contact 14a contacts the fixed contact 14b, the remaining time is displayed, and the movable contact 14a contacts the fixed contact 14.
A changeover key 15 displays an approximate amount of travel when touched by c, and a display 15 displays the amount of travel or remaining time.

Next, the operation of the circuit with the above configuration will be explained.

First, when a completely rewound cassette tape is set, the counter reset key 12 is operated to set the contents of the counter section 11 to O.

Next, when the take-up reel 2 rotates and the magnetic tape 3 is fed, the rotation of the supply reel 1 causes the reel rotation shaft 6 to rotate and the rotating body 8 to rotate. Therefore, the rotation detector 7 outputs a rotation detection pulse proportional to the rotation period. This rotation detection pulse is input to the rotation period detection section 10 and the counter section 11. Therefore, the rotation period detection section 10 detects the rotation period of the supply reel 1. and,
The counter section 11 counts the number of revolutions of the supply reel 2.
The calculation unit 13 uses the detection output from the rotation period detection unit 10 to determine the first rotational speed ■SR of the supply reel after the counter is reset, and thereby determines the radius Rs using equation (9). . Furthermore, the thickness d of the tape is determined by equation (12) using this rotational speed (R), the second rotational speed (2) after the counter reset, and the number of rotations n. Then, using the radius Rs and the tape thickness d, the constant A described above,
Find B and C. On the other hand, the counter section 11 is connected to the rotation detector 7.
The number of revolutions n of the supply reel 1 is sequentially counted by counting pulse signals output from the reel 1. Then, the constants A, B, C and the rotation speed n obtained in this way are subjected to the calculation shown in equation (7) in the calculation section 13, thereby calculating the remaining amount time t. This remaining amount time t is determined between the fixed contact 14b and the movable contact 14 of the switching key 14.
The information is displayed moment by moment on the display section 15 via a. next,
If you set a partially wound cassette tape,
When started after operating the count reset key 12, the operation is the same as described above in this case as well, and the remaining tape time t is displayed. Next, when the movable contact 14a of the switching key 14 is connected to the fixed contact 14c as shown by the dotted line, the number of rotations n for the supply reel 1 counted by the counter section 11 from the time of the reset operation to the present is displayed on the display. 15, and this display of the rotation speed n can be used as a guideline display of the travel distance.

Note that the portion indicated by the dotted line M can be configured by a microcomputer. In the example, 1 after reset
Although the V and R of the first rotation were determined, the second or third R can also be determined in consideration of the stability of the rotation. In this case, the measurement of ■ to determine d is performed in the next rotation. Also,
In the embodiment, d was calculated immediately after resetting, but if the vehicle is running at a constant speed, d may be corrected depending on the current ■ and n.

As explained above, the cassette tape remaining amount time display method according to the present invention only detects the rotational speed of the supply reel and counts the number of reel rotations, and is not affected by differences in tape thickness. Moreover, even when the running state of the tape changes or when a partially wound cassette tape is used, it has an excellent effect of being able to accurately display the remaining time of the tape.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the relationship between the magnetic tape and the take-up reel, and FIG. 2 is a block diagram showing an embodiment of the cassette tape remaining amount time display method according to the present invention. 1... Supply side reel, 2... Take-up side reel, 3... Magnetic tape, 4a and 4b...
...Guide, 5...Cassette tape, 6...
・Reel rotation axis, 7...Rotation detector, 8...
...Rotating body, 9...Detection element, 10...
...Rotation period detection section, 11... Counter section, 12
... Count reset key, 13 ... Calculation unit, 14 ... Switching key, 14a ... Movable contact, 14b and 14c ... Fixed contact, 1
5...Indicator.

Claims (1)

[Claims] 1 Measuring means for measuring the rotation period (rotational speed) of the supply reel of the cassette tape, a counting means for counting the rotation pulses of the supply reel of the cassette tape and outputting the number of tape turns n, and resetting this counting means to zero. a means for calculating a constant B based on information from the measuring means at the time of zero resetting, information from the measuring means at the time of zero resetting, and the measuring means and counting means after zero resetting. A means for calculating a constant A and a constant C based on information from the counting means, and a means for calculating a constant A and a constant C based on information from the counting means, and a running time t of the cassette tape using the information from the counting means after zero reset and the calculated constant A, constant B, and constant C. It is composed of a calculation display means that calculates and displays the calculation based on the calculation formula t=An^2-B_n+C, and cooperates with the operation of the zero reset means to calculate and display the remaining amount of time on the cassette tape. A method for displaying the remaining amount of time on a cassette tape.