JPS6326859A - Tape drive controller - Google Patents

Abstract

PURPOSE:To make the tape tension constant without complicated arithmetic operation even at a high speed tape running by calculating the radius of a supply tape based on the result of detection of the drive speed of both reels so as to control the supply reel motor. CONSTITUTION:Drive speed information detectors 7, 8 detect driving periods ts, tv of supply/winding reels 2, 4 respectively and a supply side tape radius calculator 9 calculates a radius rs of a tape 1 of the supply reel based on equation. A reel motor 5 is controlled via a supply reel motor drive control circuit 10 in response to the radius rs and the tape tension is controlled to be nearly constant even at the fast forwarding. In using the reels 2, 4 for the winding and supply reels respectively, the similar circuit is used to obtain the similar result, then no complicated arithmetic operation is required even at high tape running such as fast forwarding or rewinding to make the tape tension constant thereby stabilizing the tape running. In equation t0, r0 are driving periods at capstan feeding.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to, for example, a direct drive type VTR or R-D AT where both reels are directly driven by a dedicated motor.
(Rotary Digital Audio Tap
The present invention relates to a tape drive control device that performs control to suppress fluctuations in the tape tensicon when running the tape at high speed in an e-reke order.

(b) Conventional technology Conventionally, reel direct drive type VTRs
In order to always carry out stable tape running in R-DAT and R-DAT, it is necessary to maintain an appropriate tape tensicon throughout the tape running. In particular, in the high-speed search operation of R-DAT, 1. In order to stably reproduce No. 16 recorded on tape, considerable running stability is required.

Therefore, in order to control the tape tension at a constant level during high-speed arp running, the back torque generated by the supply reel motor should be directed in the opposite direction, which is proportional to the radius of the tape that has been completely wound around the supply reel hub. It is sufficient if the torque can be controlled to a value obtained by subtracting the forward direction (i.e., tape feeding direction) torque that compensates for the friction of the supply side rotation system from the torque (direction); in this case, if the friction is low, this compensation may be omitted. . As a device that almost satisfies this demand, a tension-control device as disclosed in Japanese Unexamined Patent Publication No. 57-40774 has already been proposed. When running the capstan with known speed Vo (during normal playback)
By subtracting the rotational angular velocity ω of the supply side reel hub in , the winding tape half (, 3r) is determined by the following formula (1).

Therefore, in order to keep the tape tension T constant, the bank torque that the supply side reel motor should generate is calculated by the following formula 7 (%), omitting the friction (friction) and torque mentioned above in the introduction of the die joint drive. (2).

Therefore, by substituting the 1st equation into the 2nd equation, we get τ-T-v
o/ω (3), and the tape tension T is controlled to be constant by generating a bar/torque that is inversely proportional to the rotational angular velocity ω of the supply side reel hub.

(C) Problems to be Solved by the Invention However, the conventional method of refusing is effective only when the tape speed is known, such as when running the capstan, and is effective only when the tape speed is not determined. This method cannot be applied during high-speed tape running, such as when returning the tape, or during reel running.

(d) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a tape drive control device in which the tape is run by a pair of reel motors, in which the rotational speed, rotation period, etc. of both reels are controlled. rotational speed information detection means for detecting rotational speed information of each;
supply-side tape radius calculation means for approximately calculating the radius of the tape wound on the supply-side reel using a linear equation of the rotational speed information obtained from the rotational speed information detection means; and receiving the output of the supply-side tape radius calculation means. A supply reel drive control means for controlling the supply side reel motor is provided.

(e) Effect: According to the tape drive control device of the present invention having the above-mentioned configuration, the tape tension can be kept almost constant even during high-speed tape running such as fast forwarding or rewinding where the tape speed is not constant, without having to perform complicated calculations. This makes it possible to increase the discretion of high-speed searches and to save labor and reduce costs for the reels and motors used.

(f) Example An embodiment of the present invention will be described below with reference to the drawings.

That is, the present invention seeks to determine the radius of the wound tape in response to the ever-changing tape speed, and to control the tape tension at a constant level even when the tape is running at high speed, such as during fast forwarding or rewinding.

First, in order to keep the tape tension constant, in the case of a direct drive system, it is sufficient that the back torque generated by the supply side reel moke can be controlled as shown in the following equation 7, %(4). Here, r is the radius of the wound tape on the supply side, τ is the friction torque due to the axis and viscous friction of the rotation system on the supply side, and τ is the shaft loss torque.

, the viscous friction coefficient is R1, and the rotational angular velocity of the supply side reel hub is ω, then τt11″τO+R・ωS...5)
However, depending on the case, this may be omitted from equation (4).

Therefore, the radius r of the wound tape on the supply side, which is the object of the present invention, is
, where the tape speed is V, r 5 = V /ω,
...It is determined by (6), but when the tape is running at high speeds such as fast forwarding or rewinding, it is necessary to determine the tape speed ■, which changes moment by moment, and this tape speed V can be determined as follows. . In other words, for any given tape, the sum of the cross-sectional area of the tape wound around both reel hubs and the area of both reel hubs remains unchanged at any tape position, so the following formula (%) Current supply side and winding (
The radius of the wound tape is r, , r a. are the winding tape radii on the supply side and the winding side when the capstan runs, respectively.

and each radius r3, rl, r,. ,r,.

is, rs=V/ωs+ri=”/ω750=V 6/ωSO+j?.7Vo/ω7゜
... (8), so we can convert this equation (8) into equation (7)
Substituting into the formula, the following formula % formula % (9) holds true. Further, each rotational angular velocity is calculated as ωi=2π/t using the rotation period ti of each reel hub.
1 (i=s, T, So, To,) ... (10), so substituting this into equation (9) yields V2 (
t2s +t2. )=V2゜(t2so+t2to)
・(tt) holds true. That is, the tape speed V, which changes from moment to moment, can be calculated from the following equation by measuring the rotation period of both reel hubs.

Therefore, the equation (10) and the equation (1) obtained in this way
When formula 2> is substituted into formula (6), the final tape radius r on the supply side becomes as shown in the following formula.

Therefore, the rotation period tso+tto of both reel hubs during capstan running and the current rotation period ts of both reel hubs,
By measuring tT, the tape radius rs on the supply side can be found using equation (13), and by substituting this into equation (4) and applying the back torque to the reel motor on the supply side, tape speed fluctuations can be controlled. It is possible to run the tape at a constant tension regardless of the tension.

However, the radius calculation process using formula (13) requires complicated calculation processes such as squares and square roots, and it is difficult to construct a simple circuit system. It is necessary to approximate

That is, t'sa+t'to, 1/1+
t't/〒T due to ease of calculation for both terms. ,
ta. .

Considering approximation to the linear equation of t T / t s,
The following approximate expression can be obtained.

i”so+ t”to 牟C+(t so+ t to
)...(14) Therefore, this approximate formula can be expressed as (13)
When applied to the equation, the approximate value of r, / can be found by the following equation.

”K+ ・Vo(tso+tyo)(K+”tt/li
) ”・(16)(However, K,=C,・C3/2
π, Kj=CI/C5) This approximate formula is tso, ty. ,
Since this is a simple formula for ta/ts, tape tension can be controlled with a simple system by using this formula to find the tape optical diameter and controlling the bank torque of the supply reel motor. I can do it.

Next, FIG. 1 shows an example of the system configuration of a direct drive power type tape drive control device to which the present invention is applied.
1) is the tape wound around the supply reel hub (2), 3) is the tape that has been completely wound around the take-up reel hub (4), and (5) and (6) are the tape wound around the supply and take-up reel hubs. supply and take-up side reel motors, which are respectively directly connected to the
(7) and (8) are supply and take-up side rotation speed information detectors that respectively detect rotation speed information such as the rotation angular velocity or rotation period of the supply and take-up side reel hubs, and (9) is the inscribed rotation speed information. a supply tape radius calculator (10) that calculates the radius of the tape wound around the supply reel hub from the rotational speed information of both reels obtained from the detectors (7) and (8), respectively;
) is a supply side reel motor drive control circuit, and (11) is a take-up side reel motor drive control circuit.

Then, the take-up side reel motor drive control circuit (11) refuses.
For example, during tape fast forwarding, constant voltage drive, constant rotation drive control, etc. are performed on the reel motor (6) on the winding side, whereby the tape is wound at high speed from the reel hub (2) toward the reel hub (4). Also, the rotation period t s of this Shigure reel Hap (2) (4).

t□ is detected by rotational speed information detectors (7) and (8), and ts and tτ information are sent to a tape radius calculator (9) on the supply side. Then, the supply side tape radius calculator (9) is
16> An approximate value of the tape radius r on the supply side is determined according to the formula (1) and sent to the reel motor drive control circuit (10).
is the formula (4) or in the formula (4), follow the formula set as -0. If τ is not set as -0, the output of the detector 7) must also be derived to the control circuit (10). ) The supply side reel motor (5) is driven and controlled with a back torque τ, and as a result, the tape tension during running is controlled to be approximately constant.

Although the figure only shows tape rapid forwarding, a similar system can be used to run the tape at a constant tension during rewinding, simply by reversing the handling of the supply side and take-up side.

Next, Figure 2 shows the relative error of approximation of equation (10) by
The figure shows the relative error of approximation of equation (11) as h R-OAT
It is plotted as C1■0.7361 C3 Yuki 0.9696 C8 Otori-0,2522 (17). That is, No. (14), (
15) The ratio of the right side and the left side of the equation is the following equation C, (11?./
ls. )/AT■777πF...(18)(C, +(
3t t/l S) V'Tπ ``7 blasphemy 7 ... (19
), and in this formula, the relative ratio between the approximate value and the true value is tl.

/ts. ,t? Since it can be expressed as a function only of /ts, it can be seen that the relative error of the approximation value is determined only by the tape position when the rotation period of the reel hub is measured. Therefore, the value t? does not represent the tape position. 6/
If we show the relative error for all possible values of tso, t↑/ts, we can find the maximum and minimum values of the error, and if we plot the relative error using these, we get Figures 2 and 3. A graph of will be obtained.

That is, in the case of R-D AT, the maximum diameter of the wound tape D
max is 36.5nn, minimum value Dm of wound tape diameter
In, that is, the hub diameter is determined to be 1511+1, so
Both tTo/lso and t1/tg have values in the following ranges.

t Ding a/ t so, t Y/ t
s -15/36.5~36.5/15-0.41
10~2.433...(20>Here, Cl
-Cs is determined as in equation (17), (14)
The error in the approximation of equation (15) is minimized within the range of equation 20), and at this time, the ratio of the approximate value to the true value (18) and (19) are closest to 1, and have the following values: .

1/1.041~1.041 1/1.0621~1.068...<21
) (14) Since the approximation of equations (15) shows the above error, the ratio r of the approximate radius / and the true radius r obtained by equation 16) ('/r% is r s' / r s = 1 / (1,041x1
．． 068) ~1.041x1.068-1/1.112
.about.1.112, and the tape tension can also be controlled to be constant with an error of about ±10%.

(g) Effects of the Invention As described above, according to the tape running control device of the present invention, even when the tape is running at high speed such as fast forwarding or rewinding where the tape speed is not constant, the tape running speed can be maintained at an almost constant level without performing complicated calculations. Can maintain tape tension, R-DA
This is very effective for stimulating high-speed searches of T. Furthermore, since excessive tape tension is not applied at any tape position, unnecessary load is not placed on the reel motor on the take-up side, making it possible to optimally design the reel motor with labor savings and cost reduction in mind. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the system configuration of the device of the present invention, and FIG.
513 is v/'? Shows the relative error of the approximation of o+t'so.
' is a diagram showing the relative error of the approximation value. (7) (8)... Rotation speed information detector, (9)...
Supply side tape radius calculator, (10)...Supply side reel motor drive control circuit.

Claims (1)

[Claims] (1) In a tape drive control device that runs a tape using a pair of reel motors, a rotation speed information detection means for detecting rotation speed information such as the rotation speed or rotation period of both reels, and a rotation speed information detection means that detects rotation speed information such as the rotation speed or rotation period of both reels, and supply side tape radius calculation means for approximately calculating the radius of the tape wound on the supply side reel using a linear equation of the obtained rotational speed information; and control of the supply side reel mork in response to the output of the supply side tape radius calculation means. 1. A tape drive control device comprising: supply reel drive control means.