JPS6051182B2 - Cassette tape running time display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a cassette tape that can accurately display the time of tape travel regardless of tape thickness and hub, and even when changing speeds such as fast forwarding and rewinding. This relates to the driving time display method.

Many kinds of recorded contents are recorded at different positions on a single magnetic tape, and if you want to quickly obtain these recorded contents, it is convenient to know the position on the magnetic tape in advance. .

For this reason, general tape recorders are provided with a mechanical tape counter, and the position on the magnetic tape is confirmed by the count value of this tape counter, and the recorded contents are made to correspond to each other. However, while the tape counter with the above configuration is extremely simple in configuration, it is possible to perform fast forwarding or rewinding if the correspondence between the position on the tape and the count value is recorded in advance. Although an arbitrary position on the tape can be searched, if the correspondence with the total length of the tape or the running time is not obtained in advance, the running time or remaining time of the tape cannot be known at all.

As seen above, when trying to display the tape running time in a stopwatch style, if the tape running speed is constant, the correspondence with the tape position can be maintained, but if the tape is fast forwarded or rewound, etc. If the speed is changed even once, there is a drawback that the relationship between the running time display and the tape position is lost. An attempt has been made to solve this problem by detecting the rotation period or rotation speed of either the supply reel or the take-up reel, or both the supply reel and the take-up reel, and using a microcomputer or other computer to perform calculations. A method has been proposed in which a circuit performs certain calculations and displays the amount of tape travel or remaining amount. However, when such a method is used, the configuration for detecting both the supply reel and the take-up reel becomes complicated, making it impractical. In those that detect and process one of the two, variations in tape thickness and reel hub diameter are not taken into account, and therefore have the disadvantage that accurate time information cannot be obtained.

Therefore, the object of the present invention is to increase the rotation period of one reel (
A cassette that is unaffected by differences in tape thickness and hub diameter by simply detecting rotational speed (rotational speed), and can accurately display running time even when tape running conditions change. It is an object of the present invention to provide a method for displaying tape running time.

Hereinafter, it will be explained in detail using the drawings. First, as shown in Figure 1, when the radius of the hub is RO, the thickness of the tape is D, and it is wound n times on the take-up reel, the length e1 of the magnetic tape on the outer periphery is expressed by equation (1). be able to. Therefore, n
The total length l of the magnetic tape when wound can be expressed by equation (2).

Here, f)? Therefore, equation (2) can be expressed as equation (3).

When the magnetic tape is running at a constant speed VO in the x direction, the running time t from the start of winding to the present is (4
) can be shown by the formula.

In this equation (4), A=πd/VO, B=2πRO
/VO, this equation (4) can be expressed as equation (5).

Note that A is a value determined by the tape thickness d and tape speed,
B is a value determined by the radius ψ of the hub and the tape speed ψ.

Next, in actual magnetic tape, the accuracy of magnetic tape,
The apparent thickness d has a large error due to uneven winding. Since this error differs depending on the magnetic tape, it must be corrected for each magnetic tape. Next, the rotation speed VR of the take-up reel can be obtained by differentiating n in equation (5) with respect to t, and can be expressed by equation (6). In this case, the rotational speed of the take-up reel immediately after resetting the counter that counts the number of turns n of the take-up reel
If R is ■RR, the thickness d of the tape is extremely thin, less than about 18IL, the radius RO of the hub is about 11T1Un, and the number of turns n is 1, so it becomes 7((B). Therefore, the ( From equation 6), B8 immediately after reset can be obtained using the following equation.

Further, AR after reset can be obtained from equation (6).

Therefore, first, using the values BR and AR obtained by the equations (7) and (8) after performing the reset process at the start and the value n of the counter that counts the number of turns n after the reset, The running time is determined by performing the calculation shown in equation (5).

Furthermore, even if the tape is reset in the middle of the tape, the running time from the reset position can be displayed. in this case,
Since Equations (7) and (8) above do not include the terms of the tape thickness d and the hub radius ψ, they do not include any errors due to variations in the tape thickness and hub radius. 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 take-up side, 7 is a rotating body 8 attached to this reel rotating shaft 6, and a mark on this rotating body 8 is magnetically set. A rotation detector consisting of a detection element 9 that detects optically or mechanically and outputs a rotation detection pulse,
The period of this rotation detection pulse is directly proportional to the rotation period of the take-up reel 2. 10 is a rotation period detection unit that detects the rotation period (speed) by inputting this rotation detection pulse; 11 is a counter unit that counts this rotation detection pulse;
12 is a count reset key which is operated when or during setting of the magnetic tape 3 to reset the count value of the counter section 11 and set the count value to ゜゜0゛; 13 is the above-mentioned (
5) BR and AR obtained by equations (7) and (8)
14 is a movable contact 14a and a fixed contact 14.
b and 14c, and the movable contact 14a is the fixed contact 14.
When the movable contact 14a contacts the fixed contact 14c, the changeover key displays the travel time, and when the movable contact 14a contacts the fixed contact 14c, the changeover key displays the approximate travel amount. 15 is a display that displays the travel amount or the travel time.

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

First, when setting the magnetic tape, press the count reset key 1.
2 to set the contents of the counter section 11 to 0.

Next, when the take-up reel 2 rotates and the magnetic tape 3 is fed, the rotation of the take-up reel 2 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 take-up reel 2. and,
The counter section 11 counts the number of revolutions of the take-up reel 2.
The calculation section 13 calculates the (7) rotation period signal based on the first rotation period signal of the take-up reel output from the rotation period detection section 10.
The calculation shown in the formula is performed to obtain and store the value BR. On the other hand, the counter section 11 sequentially counts the number of rotations n of the take-up reel by counting pulse signals output from the rotation detector 7. Then, the calculation unit 13 calculates the output ■R of the rotation period detection unit 10 at that point.
The value AR is calculated by performing the calculation shown in Equation (8) using the count value n of the counter section 11 and the previously determined and stored value BR. The value B obtained in this way
R, AR, and n are subjected to the calculation shown in equation (5) in the calculation section 13, thereby calculating the running time t,
This travel time q is displayed moment by moment on the display 15 via the fixed contact 14b and the movable contact 14a of the switching key 14. Next, set the partially wound cassette tape,
When the count is started after operating the count reset key 12, in the first rotation of the take-up reel 2 after the reset, the calculation section 13 performs the above-mentioned (7).
It calculates the expression and holds the calculation result BR. From now on, the counter value N of the counter section 11 after reset,
By performing the arithmetic processing of Equations (8) and (5) based on the rotation speed signal ■1 output from the rotation period detection unit 10 at that point and the previously stored calculation result BR. , the tape running time signal t from the time of reset
Output. This tape running time signal t is determined by the switching key 14.
The tape running time t from the time of reset is displayed on the display 15 via. Next, the movable contact 14a of the switching key 14
When connected to the fixed contact 14c as shown by the dotted line, the number of turns n for the take-up reel 2 from the time of the reset operation when the counter section 11 is counted up to the present time will be displayed on the display 15, and this number of turns will be displayed on the display 15. The display of n can be used as a guideline display of travel distance.

When such a method is used, the value BR shown in equation (7) is calculated and stored immediately after the reset process, so the true value of the hub dimensions themselves is not included in this value BR. This means that there will be no errors due to variations in the hub.

In addition, using the value BR calculated in this way, the value AR obtained each time, and the number of tape turns n of the take-up reel after the reset, the running time t from the time of the reset operation is calculated.
Because it calculates the tape running time from any tape position, it is also possible to display the tape running time from any tape position, and even if the tape speed is changed, such as during fast forwarding or rewinding, it is possible to display the tape running time from any tape position. By using the value AR (constant), an accurate indication of tape running time can be made. In this case, the counter section 11 is switched to the addition and subtraction modes by a signal indicating the rotation direction supplied from the rotation detector 7 or an operation switch section of a tape recorder (not shown).

In the above-described embodiment, after the calculation unit 13 receives the output of the count reset key 12, the value BR is calculated when the rotation period detection unit 10 supplies the rotation period (speed) signal at the time of the reset operation. Although the case where the data is stored is explained, the present invention is not limited to this.
The count value of the counter section 11 may be ゜゜0゛, or the rotation period signal (speed) signal immediately after reset may be stored, and when the switching key 14 is switched to the traveling time display mode. Calculate the constant BR for the first time,
Arithmetic processing may be performed to calculate the traveling time based on the calculated constant BR. As explained above, the cassette tape running time display method according to the present invention only detects the rotational speed of one reel, and is not affected by differences in tape thickness or hub size variations, and It has an excellent effect of being able to accurately display the running time of the tape even when the running condition of the tape changes.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the relationship between a magnetic tape and a take-up reel, and FIG. 2 is a block diagram showing an embodiment of a cassette tape running time display system 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 rotating shaft, 7... Rotation detector, 8... Rotating body, 9... Detection element, 10...
- Rotation period detection section, 11... Counter section, 12...
Count reset key, 13... calculation section, 14...
Switching key, 14a...Movable contacts, 14b and 14c...
...Fixed contact, 15...Indicator.

Claims (1)

[Scope of Claims] 1. Measuring means for measuring the rotation period (rotational speed) of the take-up reel of the cassette tape, and counting means for counting the rotation pulses of the take-up reel of the cassette tape and outputting the number n of tape turns. a zero-resetting means for resetting the counting means to zero; a means for calculating a constant B based on information from the measuring means at the time of zero-resetting; and a means for calculating a constant B based on information from the constant B, the measuring means and the counting means. the running time t of the cassette tape is calculated and displayed based on the formula t=An^2+Bn using the information from the counting means and the calculated constants A and B; 1. A cassette tape running time display method, comprising: a calculation display means, the running time of a cassette tape being calculated and displayed from an arbitrary position on the cassette tape where a zero reset has been activated.