JP2751155B2 - Rotation phase controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rotation phase control device for a rotating system, and
It is suitable for use in a helical scan type recording / reproducing machine such as R. [Summary of the Invention] A plurality of rotation detection pulses are generated during one rotation of the rotation unit, and the pulses are counted for each rotation period of the rotation unit, and the rotation detection pulse generated corresponding to the period of the phase reference signal is calculated. By extracting based on a specific count value, a pulse representing the rotation phase is formed, the phase is compared with the phase reference signal, and the rotation phase is controlled by an error, and the phase is synchronized at a frequency that is a non-integer multiple of the phase reference signal. This is a rotation phase control device for obtaining rotation. [Prior Art] In a VTR, when recording an NTSC signal, the rotating head drum uses a 30 Hz frame pulse (1/2 of the vertical synchronization signal).
(Phase-divided signal) to apply phase servo. On the other hand, in a VTR called a 4-head small-diameter drum system in which the head drum diameter is reduced to 2/3 times and the tape wrap angle is set to 270 ° without changing the recording format, the drum has four drums.
Since the rotation is 5 times, the servo lock is applied at 15 Hz which is the greatest common divisor with the 30 Hz reference signal. [Problems to be Solved by the Invention] In the four-head small-diameter drum system, the pull-in speed of the phase servo system is half of the normal speed, and there is a problem that the response to the rise or disturbance is slow. In view of this problem, an object of the present invention is to synchronize a rotating system by sampling a phase error at the phase reference signal period even if the rotation frequency is a non-integer multiple of the frequency of the phase reference signal. [Means for Solving the Problems] The rotation phase control device of the present invention is a device for controlling the phase of a rotation unit (rotary drum 3) whose rotation period is not an integral multiple of the period of the phase reference signal. As shown in FIG. 1, a pulse generating means (FG head 7) for generating a plurality of rotation detection pulses each time the rotating unit makes one rotation, and a rotation for each rotation cycle (each output PG of the PG head 6) Counting means for counting the detected pulses (the phase measuring circuit 8 and the step shown in FIG. 6)
And an extracting means (phase measuring circuit 8 and FIG. 6) for extracting a pulse generated corresponding to the cycle of the phase reference signal from the rotation detection pulse based on the output of the counting means. and the count value of the step 9 and 13 use the time information T _FG of the corresponding detection pulses of discrimination and step 11 and 15 (FG number)), detection for detecting a phase error between the phase reference signal with the extracted pulse Means (the phase measurement circuit 8 and the detection of the phase difference in steps 11 and 15 in FIG. 6) and control means for controlling the phase of the rotating section based on the phase error (the phase compensation circuit 10 in FIG. 1, the notch filter
14, drive amplifier 15). [Operation] By extracting a pulse corresponding to the cycle of the phase reference signal from the train of rotation detection pulses based on the output of the counting means generated with the rotation of the rotating unit, the rotation having substantially the same cycle as the phase reference signal is performed. A phase representative signal is obtained. Rotating part 1
By the counting operation of the counting means for each rotation, the phase information is updated every rotation of the rotating unit, so that it is not necessary to lock the servo every several rotations with the greatest common divisor of the frequency of the phase reference signal and the rotation phase signal. In addition, phase information is taken in every rotation, and servo lock is applied for each phase reference signal, thereby improving servo response. FIG. 1 is a schematic block diagram of a drum servo system of a four-head small-diameter drum VTR to which the present invention is applied. As shown in FIG. 3, this VTR has heads 1a, 2a, 1b and 2b at every 90 ° on a rotating drum 3, and a 180 ° opposing pair 1a and 1b has a positive azimuth angle (+) and 2a and 2b. Has a negative azimuth angle (-). The magnetic tape 4 is wound about 270 °, and the drum 3 rotates at 45 times / second. The head is sequentially switched to 1a (+), 2a (-), 1b (+), 2b (-) every 3/4 rotation (270 °), and the tracks T1a, T2a, T1b as shown in FIG.
An azimuth record is being made at…. In FIG. 1, the rotation phase of the drum motor 5 directly connected to the rotating drum 3 corresponds to the recording vertical synchronizing signal (V
Reference signal (V / 2, 30 Hz) obtained by dividing the frequency of -SYNC, 60 Hz) by half
It is controlled to synchronize with. 60Hz as reference signal
V-SYNC is not used because VTR and video memory (VRA
This is because the vertical cycle of the output of M) or the video game machine may be alternately different in the field. The periphery of the rotary drum 3 is mounted magnet pieces M _PG for detecting rotational phase, PG pulses (45 Hz, Fig. 2 C) which represents the rotational phase from the PG head 6 of the fixed side can be obtained. In addition, six magnet pieces M _FG for detecting rotation speed
Are attached to the periphery of the drum at equal intervals, and FG pulses (6 pulses / revolution) shown in FIG. 2D are obtained from the FG head 7 on the fixed side. Note that the heads 6, 7 or the magnet piece M are so arranged that one of the FG pulses and the PG pulse are obtained at the same phase position.
The relative positions of _FG and _MPG are determined. The PG pulse and the FG pulse are introduced into the phase measuring circuit 8 and the speed measuring circuit 9, respectively, and the phase and speed error signals are formed by comparison with the phase reference signal V / 2 and the speed reference signal. Each error signal e _phi, e _v are added by the adder 14 via the phase compensation circuit 10, 11 and notch filters 12 and 13, are Zohaba by driving amplifier 15 is applied to the motor 5. Note that the notch filters 12 and 13 (or comb filters) are
Eccentricity or unnecessary components by angle-breaking error of the magnet pieces M _FG (in the phase system 15 Hz, the speed-based 45 Hz) is intended to remove. Since the reference signal of the phase is 30 Hz and the rotation of the drum 3 is 45 Hz, the phase reference signal of 30 Hz is converted into a PG pulse of 45 Hz and 270 Hz.
FG pulse (PG × 6). That is, FIG. 2D
As shown in the figure, the PG pulse (Fig.
Count the pulses by counting them as 0, 1, 2, 3, 4, 5, 0, 1, 2, ..., and take out the 0th and 3rd FG pulses alternately every frame (30Hz), The phase comparison is performed with the phase reference signal V / 2. Therefore, as shown in FIG.
Phase locked at Hz. FIG. 5 shows an embodiment of the phase and speed measuring circuits 8 and 9 of FIG. 1 based on the above-described principle. In this example, required functions are obtained by a program incorporated in a microcomputer.
The output pulses PG and FG of the PG head 6 and the FG head 7 and the reference signal V / 2 are supplied to the time measuring circuit 20, respectively.
It is supplied to the interrupt controller 21. The interrupt controller 21 sends an interrupt request signal IRQ and a corresponding interrupt vector to the CPU 22 for each pulse input. Each time an interrupt occurs, the CPU 22 loads the time measurement data into the RAM 24 and
Is performed based on a program in the ROM 23. Further, a phase deviation and a speed deviation are calculated, and an error signal (motor control signal) is output via the D / A converter 25. FIG. 6 shows a phase servo algorithm (interrupt routine) executed by the CPU 22. In steps S1, S3, and S6, the arrival of the reference signal V / 2, the PG pulse, and the FG pulse is detected. V / 2 is taking the time value T _V at that time in step S2 you come. When the PG comes, the PG flag PGFLAG is inverted (alternately set to “1” / “0”) in step S4, and the drum FG number DFGNO
Is set to -1. If FG comes right after that, step S7
Increments the drum FG number DFGNO by +1 and captures the time T _FG at that time in step S8. As described above, the drum FG number increases to 0, 1, 2,... And the generation time of the FG pulse is stored. Here, in steps S9 and S13, the drum FG number is “1” or “3”.
And in steps S10 and S14, the PG flag PGFL
Determine 1/0 of AG. FG number is “0” and PG flag is “0”
If the time difference between the reference signal and the 0th FG pulses calculated as the phase difference φ = T _FG -T _V in step S11, the output from the D / A converter 15 at step S12. If the FG number is “3”
If conditions are satisfied PG flag is "1", similarly to calculate the phase deviation φ = T _FG -T _V in step S15, in step S16 D / A
And output. The above processing is executed every interruption of each pulse of V / 2, PG, and FG, and the phase of the drum rotation of 45 Hz is locked to the reference signal V / 2 of 30 Hz. 7 to 9 show another embodiment. In this example, magnet pieces M _PG and 180 ° on the drum 3 as the seventh Figure
An angle difference attached auxiliary magnet pieces M _PGS of auxiliary PG to face the magnet pieces M _PGS
A head 6 'is provided on the fixed side. Therefore, as shown in the timing charts B and C of FIG.
Detection pulse P of 180 ° phase difference at 45Hz from each of heads 6 '
G and SUB-PG are obtained. By numbering these pulses in the order of generation as shown in FIG. 8D, a specific number “0” is associated with the phase reference signal V / 2 (FIG. 8A),
Phase servo can be applied. FIG. 9 shows the phase servo algorithm. Steps
At S1, S3, and S8, the generation of the reference signal V / 2, the PG pulse, and the SUB-PG pulse are detected, and the interruption process is performed. In other words, Tokomu the time T _V at that time in the CPU22 (RAM24) in step S2 If you come is V / 2. When a PG or SUB-PG arrives, the drum PG number DPGNO is incremented by one in step S4 or S9, and it is determined in step S5 or S10 whether or not this signal has reached "3". "3" capture the time T _PG in the case of (step S6, S11), and resets to "0" PG number DPGNO (step S7 or S12). As a result, a timing “0” (or “3”) of 45 Hz × 2/3 (= 30 Hz) is obtained. Next, DPGNO = 0 is detected in step S13, and a phase deviation φ = T _PG −T _V is calculated. (Step S14), D / A and output (Step S1)
Five). In the second embodiment, each of the PG pulse and the SUB-PG pulse is a pulse representing one rotation phase for one rotation, and both function as rotation detection pulses obtained by dividing the cycle of one rotation into a plurality. . [Effect of the Invention] As described above, the present invention generates a plurality of rotation detection pulses during one rotation of the rotating unit, counts the pulses for each rotation period of the rotating unit, and corresponds to the period of the phase reference signal. By extracting the rotation detection pulse generated based on the count value result, a pulse representative of the rotation phase is formed, the phase is compared with the phase reference signal, and the rotation phase control is performed based on the error. The phase-synchronized rotation is obtained at a frequency of a non-integer multiple, and the phase information is updated every rotation of the rotation unit by the counting operation of the counting means for each rotation of the rotation unit. It is not necessary to lock the servo every several rotations with the greatest common divisor of the frequency of the phase reference signal and the rotation phase signal, and the phase information is captured every rotation and the servo lock is locked for each phase reference signal. Thus, the servo response can be improved by increasing the synchronization pull-in speed of the servo system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a drum servo circuit diagram of a 4-head VTR to which the present invention is applied, FIG. 2 is a time chart of phase servo, FIG. 3 is a schematic diagram of a 4-head drum, and FIG. Fig. 5 is a recording pattern diagram on a tape, Fig. 5 is a measurement control circuit diagram of a servo system using a CPU, Fig. 6 is a flowchart showing an algorithm of phase servo, Figs. 7 to 9 show a second embodiment, FIG. 7 is a schematic diagram of a circuit detection unit, FIG. 8 is a time chart of a rotation detection signal, and FIG. 9 is a flowchart of a phase servo algorithm. In the reference numerals used in the drawings, 1a, 1b, 2a, 2b, rotary head 3, rotary drum 4, magnetic tape 5, drum motor 6, PG head 6 ', auxiliary PG head 7, etc. FG head 8... Phase measurement circuit 9... Speed measurement circuit.

Claims (1)

(57) [Claims] An apparatus for controlling the phase of a rotating section whose rotation cycle is not an integral multiple of the cycle of a phase reference signal, comprising: pulse generating means for generating a plurality of rotation detection pulses each time the rotating section makes one rotation; Counting means for counting the rotation detection pulse for each cycle; extracting means for extracting a pulse generated corresponding to the cycle of the phase reference signal from the rotation detection pulse based on an output of the counting means; A rotation phase control device, comprising: detection means for detecting a phase error between a signal and the extracted pulse; and control means for controlling a phase of the rotation unit based on the phase error.