JPH056225A - Digital rotating phase servo device - Google Patents

Abstract

PURPOSE:To provide a high-order lag-lend tipe filter used as a phase compensating filter with simple configuration by serially connecting and inserting plural first-order lag-lead filters in a phase servo loop. CONSTITUTION:First-order lag-lend type filters 31 and 32 are serially connected and inserted in the phase servo loop in place of second-order lag-lead filters. In order to constitute this connection with the software of a microcomputer, it is executed twice with the first-order lag-lead filters 31 and 32 as sub routines. In order to obtaining a desired phase compensating characteristic, in the case of executing the sub routine twice, coefficients K6-K8 of coefficient multipliers 43-45 can be made equal or different in the two times of execution. Delay time is made equal for delay equipments 41 and 42 in the two times of execution for executing the same sub routine, and the poles of the two first-order lag-lead filters are made completely coincident. Thus, neither oscillation due to deterioration in servo characteristic nor deterioration in performance of the high-order lag-lead filter is caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital rotary phase servo device used for rotary phase control of a cylinder motor or a capstan motor of an 8 mm video tape recorder (hereinafter abbreviated as "8 mm VTR").

[0002]

2. Description of the Related Art A digital servo device for an 8 mm VTR capstan motor generally has a functional block diagram shown in FIG.

In the figure, reference numeral 1 denotes a capstan motor, and an FG signal generated in response to the rotation of the motor passes through an amplifier 2 and is inputted to a speed error signal producing device 3 and a first phase error signal producing device 4. .. The speed error signal creating device 3 measures the cycle of the FG signal and creates a speed error signal. The first phase error signal creation device 4 creates a phase error signal by measuring the phase difference between the FG signal and the reference phase signal. The speed error signal and the phase error signal are added by the adder 5 and provided as a phase compensation filter 2
After passing through the lag lead filter 6, the servo gain in the low frequency band is increased, and the capstan motor 1 is driven and controlled. The above has described the case where the 8 mm VTR is in the recording mode. In the reproduction mode, the switch 7 is switched from the terminal 7a to the terminal 7b, and the phase error signal is generated by the second phase error signal generating device 8 using the 4-frequency pilot method which is the standard of 8 mm VTR. The speed error signal generating device 3, the first phase error signal generating device 4, the adder 5, the secondary lag lead filter 6, the switch 7, and the second phase error signal generating device 8 shown in FIG. Actually, it is composed of microcomputer software.

Next, the secondary lag lead filter will be described. FIG. 4 is a functional block diagram showing an example of a second-order lag lead filter. Reference numerals 11, 12, 13, and 14 denote delay times for delaying a signal for one sampling time of digital servo and 15, 16, 17, 18, and 19. Are K1 and K respectively
Coefficient multipliers for multiplying the signals by the values 2, K3, K4, K5, and 20 and 21 are adders. The difference equation of the second-order lag-lead filter shown in the figure is

[0005]

[Equation 1]

[0006]

[0007]

However, when a high-order lag lead filter is constructed by software of a microcomputer, the parameters increase and complicated calculation is required. Therefore, there is a problem that the program becomes large and the memory for storing the program cannot be effectively used.

[0008]

According to the present invention, in order to solve the above-mentioned problems, a plurality of primary lag lead filters are connected in series and inserted in a phase servo loop of a digital rotary phase servo apparatus.

[0009]

Operation A plurality of first-order lag lead filters are connected in series to function as a higher-order lag lead filter.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of the present invention. The same components as those of FIG. The difference from FIG. 3 is that two primary lag lead filters 31 and 32 are connected in series instead of the secondary lag lead filter and are inserted in the phase servo loop.

FIG. 2 is a functional block diagram showing an example of the primary lag-lead filter. As in FIG. 4, 41 and 42 are digital servo one sampling time, delay devices for delaying signals, 43, 44 and 45 are coefficient multipliers for multiplying signals by K6, K7, and K8, and 46 and 47, respectively. Is an adder. The difference equation is

[0012]

[Equation 2]

[0013]

To configure the serial connection of two primary lag lead filters with the software of the microcomputer, 1
The next lag lead filter may be used as a subroutine, and the subroutine may be executed twice. In order to obtain a desired phase compensation characteristic, the coefficients K6, K of the coefficient multipliers 43, 44, 45
7, K8 may have the same value twice when the subroutine is executed twice, or may have different values between the first time and the second time. The delay times of the delay devices 41 and 42 are the same in the first and second times because the same subroutine is executed. That is, the poles of the two first-order lag-lead filters are exactly the same. Therefore, the servo characteristics are not deteriorated and oscillate, and the characteristics of the high-order lag lead filter are not lost. Further, in order to obtain third-order, fourth-order, and higher-order lag-lead filters, the subroutine may be executed three times and four times, and it is not necessary to configure a complicated program.

[0015]

According to the present invention, a high-order lag-lead filter which does not require complicated calculation in which parameters increase can be constructed by software of a microcomputer. Therefore,
The memory for program storage can be effectively used, and the effect is great.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.

FIG. 2 is a functional block diagram showing a main part of the embodiment shown in FIG.

FIG. 3 is a functional block diagram showing a conventional technique.

FIG. 4 is a functional block diagram showing a main part of the conventional technique shown in FIG.

[Explanation of symbols]

 1 ... Capstan motor 3 ... 1st phase error signal preparation apparatus 31, 32 ... 1st-order lag lead filter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G11B 15/467 Q 8110-5D

Claims (1)

Claim: What is claimed is: 1. A digital rotary phase servo apparatus comprising a plurality of first-order lag lead filters connected in series in a phase servo loop.