JP2700410B2 - Tape speed control method at the time of search etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a tape search and a fast-forward in a device using a tape such as a video tape recorder (VTR), a digital audio tape recorder (DAT), a cassette tape recorder, etc. The present invention relates to a method for controlling a tape speed when a high-speed drive such as rewinding is started.

[Prior Art] In this type of tape-using apparatus, a tape search,
When starting high-speed driving such as fast-forwarding and rewinding, conventionally, the speed up to the target high-speed speed is, for example, 0 → 50 → 10
It has been practiced to divide and start up at a plurality of stages, such as at 0x speed. By the way, 46 minutes, 60 minutes, 90 minutes on tape
There are multiple types of (time) such as minutes and 120 minutes, but since the type of tape has not been discriminated in the past, the time required for high-speed driving of the tape was adjusted to the 120-minute tape, which is the most demanding condition. Speed control.

[Problems to be Solved by the Invention] Since the drive of the tape is controlled in accordance with the tape for 120 minutes without discriminating the type of the tape as described above, the speed varies depending on the type of the tape. Variation increases. In particular, the difference between the 46-minute tape and the 120-minute tape is large.

Further, when the speed is rapidly increased, there is a problem that data is instantly read out at the time of speed switching.
Furthermore, the speed at which the tape enters the tape end varies and varies depending on the type of tape. Driving the tape at double speed is described in, for example, JP-A-61-198460, and controlling the speed of the tape is described in, for example, JP-A-58-198460.
In Japanese Patent No. 32259, the means for determining the type of tape is disclosed, for example, in JP-A-58-6544 and JP-A-58-29156, respectively. No consideration is given to high-speed winding drive control near the end. In addition, when detecting near the end of the tape, driving the tape at a constant double speed different from the constant double speed at a high speed during steady winding is disclosed in, for example,
59-210557, JP-A-59-107444, JP-A-60
No. 195754 and Invention Technical Publication No. 77-202
However, it does not disclose a speed control method when winding is started near the tape end.

The present invention solves the above-mentioned problem. The type (time) of the tape is determined, the linear velocity is always kept constant, the high-speed driving speed at the time of search is constant for any tape, and a mechanical mechanism is used. To provide a tape speed control method capable of increasing the speed up to a limit speed at which the tape can be read, performing a search or the like in the shortest time, and further reducing the inrush speed to the tape end to a predetermined low double speed. With the goal.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method in which a tape is fed at a predetermined speed before a high-speed drive such as a tape search is started.
The respective pulse periods obtained by the rotation of the take-up reel and the take-up reel at that time are measured, and the sum of the squares of the respective pulse periods is obtained by calculation. The tape type is determined by comparing the calculated theoretical value, and after this tape determination, the sum of the theoretical value obtained by calculation according to the tape type and the double speed and the square of the pulse period of both reels is measured. Comparing with the calculated value, when winding is started near the beginning of the tape, the tape is accelerated along a predetermined quadratic curve and driven at double speed, and further, near the tape end based on the pulse period. When it is detected, it is decelerated along the quadratic curve and driven at a predetermined double speed lower than the double speed. On the other hand, when winding is started near the tape end, the same as the quadratic curve is used. Accelerate along the curve The serial is a tape speed control method in the search or the like to wind up at a low speed until the tape end.

[Operation] According to this speed control method, the tape type is determined before the high-speed drive such as search, fast-forward, and rewind of the tape is started, and the linear velocity obtained according to the determination result and the double speed number is determined. The tape speed is controlled with a target of a theoretical value that is always constant. In the vicinity of the tape end, the tape driving speed is controlled to a predetermined double speed which is lower than the above double speed. At this time,
2 which is the same as that from the tape stop state to the high-speed drive state
The speed is reduced or increased along the next curve.

[Embodiment] At the time of tape fast forward (FF), rewind (REW), and search in a tape using device, even if the tape speed is a tape portion (start of winding, end of winding, etc.), a constant speed, that is, a linear speed In order to make the speed constant, it is necessary to control the rotation of the tape reel. The theory of the condition will be described below.

In FIG. 1, a reel RS is a winding side and a reel T
Is a take-up side, the tape is t minute tape, search, FF / REW at reel S is x _S (rev / sec), reel RT is
Rotates at x _T (rev / sec) and the tape speed V _tp during playback is 8.1
5 mm / sec, and the linear velocity of the tape during search FF / REW is V _t mm
/ Sec and a tape radius r ₂ is wound around the reel S, tape radius r ₁ is wound around the reel T, hub and Fai15.
Further, it is assumed that a pulse generating mechanism for outputting A pulses in one rotation in response to the rotation of the reel is provided.

The mechanism currently used in the DAT generates 16 pulses (A = 16) per rotation.

In the state of FIG. 1, assuming that the area of the tape portion is S and the area of the hub is S _H , S _H = π × (7.5 × 10 ⁻³ ) ² = 1.76714 × 10 ⁻⁴ (m ² ) S = π (R ₁ ² + r ₂ ² ) −2S _H ... Also, assuming that the tape thickness is 13 μm and the tape length is 1, l = V _tp × t × 60 = 0.489 t (m), so that S = S 13 ^{× 10 -6 × l = 6.318 ×} 10 -6 × t ... Therefore, ^{_{more, r 1 2 + r 2 2}} = (S + 2S H) / π = 2.011 × 10 -6 × t + 1.125 × 10 -4 ... here, wound per second (wound are) tape length, a reel RT; 2πr ₁ · x _T reel RS; because it is _{2πr 2 · x S, 2πr 1} · x T = V t 2πr 2 · x S = V t Holds. Therefore, when substituting r ₁ = V _t / 2πx _T ... R ₂ = V _t / 2πx _S ... Into the equation, (V _t / 2πx _T ) ² + (V _t / 2πx _S ) ² = 2.011 × 10 ⁻⁶ × t + 1.125 × 10 ^-4 The periods T _T and T _S of both reel pulses are obtained by substituting T _T = 1 / Ax _T ... T _S = 1 / Ax _S. The equation, the right side of t, A is in order to fix the V _t because it is constant, it can be seen that the square of the sum of the periods of both reels pulse must be constant.

Next, a method of controlling the reel speed during the search and FF / REW will be described.

This type of high-speed drive gradually increases the tape speed after receiving a command. At present, the DAT mechanism used starts up to its limit speed of 120 times, winds up the tape at a constant linear speed near the end of the tape, and gradually detects the end of the tape. Wind up to the tape end at about double speed. This is shown in FIG.

The resolution at startup of the speed is 17 in the following embodiment.
Although it is a stage, the coefficient of u in the following expression is reduced,
By increasing the maximum value of u, the stages can be infinitely divided.

The detection near the tape end is performed when the thickness of the tape wound around the hub on the side to be wound becomes 1 mm. When the pulse period T _T at that time, the T _S and T _END, T _END is determined by _{T END = 2π × 8.5 × 10} -3 / (A × V t) ≒ 3.34 / V t.

When winding from near the tape end to the end, 25
Then increase the speed to double speed, and then, as usual, keep the speed of 25 times and wind up to the end.

FIG. 3 shows a flowchart of a main routine of the tape speed control at the time of search and FF / REW (high-speed drive).
This operation is performed by a program of a microcomputer. In the following, this operation will be described. First, in step S10, the double speed coefficient u and the tape end detection flag T _END are set in step S10 until a high-speed drive command FAST = 1 comes in step S1 (hereinafter simply referred to as S1). Initial setting is made as 0. When the signal of FAST = 1 comes, the coefficient u is calculated in S2.
Is checked whether u = 0, and since u = 0 at first, the subroutine for detecting the tape time (type) in S11 is executed.

Here, the operation of this subroutine will be described with reference to FIG.

In detecting the tape time, first, the tape is fed (here, the capstan is driven) at a predetermined speed for a predetermined time (S21, S22). Here, PLAY × 2 is set to 2.66 times speed, and an experience value may be put in the waiting time (weight 1).

Now, let T _T ² + T _S ² corresponding to the left side of the equation be T, and A = 16 in the case of DAT as A on the right side of the equation.
When substituting As T _VT . T is a value obtained by measurement computation of the number of reel pulses, T _VT becomes a theoretical value obtained by calculation when the constant linear velocity V _t at t time tape.

The T _VT (theoretical value) at the time of PLAY × 2 is obtained in advance as follows according to the tape time (type).

Tape time T _VT (theoretical value) 120 minutes 11.61 × 10 ^-2 90 minutes 9.63 × 10 ^-2 60 minutes 7.65 × 10 ^-2 46 minutes 6.73 × 10 ^-2 Therefore, after S21 and S22, S23 to S25 and S27 By comparing the magnitude of the measured value T with a predetermined value in S29, S29,
In S28, S30, and S31, a 46-minute tape (t = 46), a 60-minute tape (t = 60), a 90-minute tape (t = 90), and a 120-minute tape (t = 120) can be determined.

The operation after the detection of the tape time, that is, the determination of the type of the tape, will be described again with reference to FIG.

In S12, the linear velocity V _t of the tape is set. This setting is changed every time the coefficient u output from the microcomputer passes through a constant speed convergence subroutine described later.

Here the linear velocity V _t in is set to ^{(0.46u 2 +3) × 8.15 ×} 10 -3. Here, 8.15 × 10 ⁻³ is the speed at the time of reproduction, and if the double speed number (0.46u ² +3) is y, y = 0.46u ² +3... And u in this equation is changed from 0 to 16. And the double speed number y
Is as follows.

Next, the process proceeds to S13, where a subroutine for constant speed convergence is executed. This operation will be described with reference to FIG.

The constant speed convergence, performs a start-up or falling edge, of the speed, first, if not close to the tape end at S41 (T _END ≠ 1), proceeds to S42, in the set V _t and the measured values T Compare the theoretical value (target value) T _VT and
> Unless T _{VT, the} tape speed is slow, so 1LSB in S43
The tape speed is increased by (the least number of bits), a waiting time (wait 2 including the experience value) is taken in S44, and the process returns to the main routine. After that, the tape speed increased and S42
If T> T _VT , the measured value has reached the target value, so the coefficient u of the double speed is set to +1 in S45, and the process returns to the main routine. By repeatedly executing this subroutine, the tape speed can be gradually increased.

When near the end of the tape is detected, T _END = 1
Then, the flow shifts to S46, where it is checked whether the coefficient u is smaller than 7. That is, when the coefficient u is 7, as shown in the above table, the double speed number y is 25.54, and if u <7, the speed is too fast. Therefore, the tape speed is reduced in S47 to S50. This operation is the reverse of the above-described operation of increasing the tape speed, and the coefficient u is gradually reduced by -1. Also, S4
If u <7 at 6, the tape speed is lower than 25 times speed, so it is checked at S51 whether u> 6 and u
If> 6, the speed is too low. If u> 6, the speed is too low. Therefore, the process proceeds to S42, and the processing at S43 to S45 is performed to maintain a constant speed.

After the constant speed convergence subroutine, the process proceeds to S7 of the main routine in FIG. In S7, it is checked whether the coefficient u is 17 or more, that is, whether or not the maximum set speed is exceeded. If it is, u is decremented by 1 (S16). There examined whether FF direction, if FF direction, as compared with the pulse period _{T eND} ≒ 3.34 / V _t and the pulse period T _S of the take-up reel at the time of detecting the vicinity tape end as described above, the tape end Proximity detection is performed. Here, if _{T S} <3.34 / V _t, as detection flag T _END = 1 because it is near the tape end (S18), returns, else, the routine returns. on the other hand,
If it is not in the FF direction, the pulse cycle T _{T of the} take-up reel
Comparing the 3.34 / V _t, the same processing.

Next, if u = 0 in S2, u> 1 in S3 and S4.
It is checked whether 5 and T _END = 1, and when u is 15 or less and when T _END = 1, the process proceeds to S12, and thereafter, the same operation is repeated. u is greater than 15, and
If T _END = 1, the measured value T is compared with the theoretical value T _VT in S5 and S6, and the tape speed is set to 1 LSB according to the result of this determination.
Down or up (S14, S15), function to maintain a constant speed. The value of u at this time is 16, which is the maximum setting double speed of 120 times.

By executing the operation of the above-described flowchart, at the time of search, FF / REW, the tape is fed at a predetermined speed and the tape time is detected before entering the high-speed drive, and the linear velocity of the tape at the subsequent high-speed drive is detected. However, the speed is controlled so that the speed is constant on any tape.

Further, in the above-described embodiment, the speed is gradually increased in 17 divisions, so that data is not instantaneously missed during speed switching. The number of divisions can be further increased.

In addition, the speed at which the tape enters the tape end is constant, and the search does not vary depending on the tape time or from anywhere. In this embodiment, when the vicinity of the tape end is detected, a 25-times speed is set.

[Effects of the Invention] As described above, according to the control method of the present invention, at the time of tape search and FF / REW drive, the type of the tape is determined in advance, and the result and the linear velocity during double-speed drive are made constant. Speed is controlled based on the theoretical value and the measured value, so that the speed in the steady state can be constant regardless of the type of tape, and therefore, the high speed is set to the limit value that can be read by the mechanical mechanism. The search can be performed in the shortest time. In the vicinity of the tape end, if the tape speed at that time is higher than, for example, 25 times speed, the speed is reduced, and if it is lower than 25 times speed, the speed is increased despite the vicinity of the tape end. As a result, even when winding is started near the tape end, winding can be performed in the shortest time, and the impact given to the tape cassette at the end of winding is within an allowable range, thereby preventing tape breakage and solid winding. . Furthermore, whether the winding starts from the beginning of the tape or the vicinity of the end of the tape, the speed up / down is performed along with the acceleration along the quadratic curve, so that the speed transition is smooth. And the reading error is eliminated, and the time required for winding the same amount can be reduced.

Further, since the control method of the present invention can use servo control by a software program, there is an effect that the degree of freedom in design is large, the reliability is high, and the cost can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a tape reel configuration in which the method of the present invention is performed, FIG. 2 is a diagram showing a relationship between a tape speed and a tape position according to the method of the present invention, and FIG. 3 is a main flowchart for implementing the method of the present invention. FIG. 4 is a flowchart of a subroutine for detecting a tape time, and FIG. 5 is a flowchart of a subroutine for constant speed convergence. RS: reel on the winding side, RT: reel on the winding side,
T: Measured value of reel pulse cycle, T _VT : Theoretical value of reel pulse cycle.

Continuation of the front page (56) References JP-A-61-198460 (JP, A) JP-A-58-6544 (JP, A) JP-A-59-210557 (JP, A) JP-A-58-32259 (JP) JP-A-58-29156 (JP, A) JP-A-59-107444 (JP, A) JP-A-60-195754 (JP, A) Jikku Sho 62-35157 (JP, Y2) Technical report No. 77-202

Claims (1)

(57) [Claims] 1. A tape is fed at a predetermined speed before a high-speed drive such as a tape search is started, and a pulse cycle obtained by rotation of a take-up reel and a take-up reel at that time is measured. The sum of the squares of the pulse periods is obtained by calculation, the measured calculation value is compared with a theoretical value obtained in advance for each tape type to determine the tape type, and after this tape determination, the tape type and When the winding is started from near the beginning of the tape, the theoretical value obtained by calculation according to the double speed number and the calculated value of the sum of the squares of the pulse periods of both reels are compared. Is accelerated along the quadratic curve and driven at double speed. Further, when near the tape end is detected based on the pulse period, the speed is reduced along the quadratic curve and at a predetermined double speed lower than the double speed. Drive, meanwhile, tape end When you start winding from the near, the tape speed control method at the time of searching was characterized by accelerating along the same curve and the quadratic curve winding up the tape end at the low speed and the like.