JPH04251484A - Method for detecting current position of tape - Google Patents

Abstract

PURPOSE:To provide the tape current position detecting method which can grasp the current position of the tape and display remaining time without executing reel calculation even during and just after a fast forward or rewind operation. CONSTITUTION:A CPU 1 temporarily grasps the current position by the reel calculation and based on the result of the reel calculation, the remaining time of the tape or the like is displayed at a display part 7. Simultaneously, the cumulative pulse number of a take-up side reel is measured. Afterwards, when the fast forward/rewind operation of the tape is executed, the current position is grasped based on a change including the increase/decrease of the cumulative pulse number without executing the above-mentioned reel calculation and based on the position, remaining time display or the like is executed.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention is applicable to tape recorders and DA
The present invention relates to a method for detecting the current position of a tape at T. 2. Description of the Related Art In devices that run a tape, the current position of the tape is detected and the current position or remaining amount of time is displayed. To this end, conventionally, a method has generally been adopted in which the current position is detected by so-called reel calculation, in which the pulse period obtained by the rotation of the take-up reel and the supply reel of the tape is calculated. Problems to be Solved by the Invention By the way, in the case of reproducing operation, it is sufficient to increase or subtract the actual operating time.
When fast-forwarding or rewinding, reel calculations must be performed again. However, since it takes 20 to 30 seconds for the reel operation to perform the playback operation, the current position cannot be confirmed during that time, including during the fast-forwarding and rewinding operations. The present invention solves the above-mentioned problems, and is capable of detecting the current position of the tape even during fast-forwarding or rewinding operations and immediately after that, and is capable of displaying the remaining amount of time, etc. The purpose is to provide a method. Means for Solving the Problems In order to achieve the above object, the current tape position detection method of the present invention calculates the pulse period obtained by the rotation of the tape take-up reel and the supply reel. In addition to measuring the cumulative number of pulses on the take-up reel, when the tape is fast-forwarded or rewound, the current position is detected based on changes in the cumulative number of pulses, including increases and decreases. It is designed to detect. [0006] According to the above method, the current position is once detected by reel calculation, and the remaining tape time etc. are displayed based on the result of the reel calculation. At the same time, the cumulative number of pulses on the take-up reel is measured. After that, when the tape is fast-forwarded or rewound, the current position is detected based on changes, including increases or decreases, in the cumulative number of pulses, without performing the reel calculation, and the remaining time is displayed based on that. etc. Embodiment An example of a configuration for implementing the method of the present invention is shown in FIG. The control CPU 1 controls tape running and detects the current position of the tape based on input signals. A motor 2 on the tape supply side (supply side) and a motor 3 on the winding side (take-up side) each drive the tape reel based on commands from the control CPU 1. Reel pulse generators 4 and 5 generate pulses corresponding to the rotation period by rotation of the reels on the supply side and take-up side, respectively. The control CPU 1 takes in this reel pulse and performs predetermined calculations to determine the current position and remaining time of the tape. This result is given to the display unit 7 via the display CPU 6 and displayed. Furthermore, the CPU 1 measures the cumulative number of pulses on the take-up reel, and when the tape is fast-forwarded or rewound, the CPU 1 detects the current position based on changes, including increases and decreases, in the cumulative number of pulses. That's what I do. FIG. 2 shows a flowchart of processing operations by the CPU 1. The processing operation will be explained below. When the tape is inserted and the playback operation is performed (#1), reel calculation is performed based on the reel pulse and the current position is detected (
#2). Next, the cumulative number of pulses is measured (#3),
Based on the measurement result in #3, the current position or remaining time of the tape is displayed (#4). After that, when fast forwarding and rewinding operations are performed (#5), the current position is detected based on the change in the cumulative number of pulses due to the increase or decrease of pulses at this time (
#6), if the tape is not ejected (NO in #7),
Returning to #4, the current position or remaining time of the tape is displayed, including during fast forwarding and rewinding operations. The process ends when the tape is ejected. FIG. 3 shows the relationship between the tape supply side and the take-up side.The current position of the tape is detected based on the reel calculation in the above flowchart and changes in cumulative pulses due to pulse increases and decreases. The calculation formula for this will be explained. Here, v0: Tape speed 8.15 x (1/103) [
m/s] rh: Hub radius 7.5 x (1/103) [
m/s]rs: Supply side winding radius [m]rt
: Take-up side winding radius [m] d : Tape thickness 13×(1/106) [m]. The rotation period of the hub on the supply side and take-up side is Ts, respectively.
, Tt. The tape partial area Ss on the supply side is Ss=πrs 2 −πrh 2

...■, so the total tape length ls is π(rs 2 - rh 2
) ls=────────────

...■ Represented by d. Also, when rh is expressed as Ts, v0 ・
From Ts=2π・rs, rs=v0・Ts/2π
...■, so by substituting this into the formula ■, π v0
2 ls= ─( ──Ts2 -rh
2)
…■ d 4π2
becomes. Therefore, the remaining amount time R on the supply side is
ls v0
π・rh 2 R=────=───Ts2
−──────
…■ v0 4π
d v0 ·d. Similarly, the elapsed time N on the take-up side is v0
π・rh 2 N=───
Tt2 -──────
…■
It is expressed as 4πd v0 ·d. Moreover, the total time L can be obtained by adding ■ and ■. L=R+N

...■ Let P be the cumulative number of pulses on the take-up side. If no tape is wound on the take-up side, the total number of pulses is 0, and if pulses are added from there, the tape position can be determined from the number of pulses. The number of tape windings is (rs − rh )/d
Therefore, if the winding radius of the tape is known, the total number of pulses P can be calculated using the following equation assuming that one rotation is 8 pulses. rs −rh P=────────×8

…■ d Here, if you substitute the ■ formula, 8 v0 ・Tt
P=───(──────-rh)
…■
The current cumulative number of pulses can be determined by d2π. Furthermore, in order to count the number of pulses and calculate the elapsed time by increasing or decreasing the number of pulses, the equation (2) is modified,
2π P・d Tt=
────(────+rh)
…(10)
By substituting the v08 equation (10) into the equation (2), an equation for determining the elapsed time N from the cumulative number of pulses P can be obtained. v0 4π2
P・d π・rh 2
N=────・────( ───+rh)2
−────── 4πd v0
2 8
v0 ・d π P
2 ・d2 P・d・rh
π・rh 2 =────(──
────+──────+rh2)−──────
v0 ・d 64
4
v0 ・d 64・π =─────(d・P2 +16・rh
・P) …(11)
v0 If the total time L is known, the tape thickness can be determined by the following equation by modifying equation (2). v0
π・rh 2
L=────(Ts2 +Tt2)-2・──
───── From, 4
πd
v0・d1
v0
π・rh 2 d= ──{───(
Ts2 +Tt2 )-2・──────} …(1
3) L 4π
v0 [0012] FIG. 4 shows the cumulative number of pulses P on the take-up side.
This is a table showing the relationship between N and the corresponding elapsed time N, and is calculated by setting d in equation (11) to 13.0×(1/106) [m]. The current position of the tape can be detected from changes in the cumulative pulses. In addition, as shown in the above flowchart, the current position of the tape is determined in advance by reel calculation during playback immediately after tape insertion.
If you start playback from the middle of the tape, fast forward/
Even if a rewinding operation is performed, the current position can be detected by measuring changes in the accumulated pulses. [0013] As described above, according to the present invention, after performing reel calculation, the current position is detected by measuring the increase/decrease change in cumulative pulses, so that fast forwarding and rewinding operations are possible. If you do so, you can display your current location and remaining battery time during and immediately after the operation. Furthermore, there is no need to perform reel calculations to detect the current position every time a fast forward or rewind operation is performed. Furthermore, even if the present invention is not equipped with a device equipped with a software servo that calculates when the end of the tape is near and reduces the tape running speed at the end of winding to prevent damage to the tape, the present invention can be used to move the tape at low speeds. It is possible to drop it to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of equipment in which a method for detecting the current position of a tape according to the present invention is implemented.

FIG. 2 is a flowchart showing an example of the processing operation of the detection method.

FIG. 3 is a diagram of the tape supply side and take-up side for explaining the calculation formula of the detection method.

FIG. 4 is a diagram showing the relationship between the cumulative number of pulses and the corresponding elapsed time.

[Explanation of symbols]

1 CPU 4,5 Reel pulse generator 7 Display section

Claims (1)

[Claims] [Claim 1] The current position is determined by calculating the pulse period obtained by the rotation of the take-up reel and the supply reel of the tape, and the cumulative number of pulses of the take-up reel is measured, and the tape is fast-forwarded. - A method for detecting the current position of a tape, characterized in that when a rewinding operation is performed, the current position is calculated based on changes, including increases and decreases, in the cumulative number of pulses.