JPH02197282A - Rotation controller - Google Patents

Abstract

PURPOSE:To prevent fluctuation of rotation by starting phase control when the detected number of revolutions is approximately equal to a reference signal formed through frequency division of a clock having a higher frequency than the rotary frequency and resetting the frequency division means. CONSTITUTION:When a record/reproduction starting signal R/P is inputted from an operating section 13 through a system control section 14, a motor 1 is started and when the speed of the motor approaches to a target speed, a contact 16 is connected to R for recording operation and connected to P for reproducing operation. Clocks CL having higher frequency than that of an output signal FG from a speed detector 2 are produced for recording operation, and phase control is carried out based on phase control information EP formed of phase difference between phase difference signals RP, FG frequency divided through a counter 5'. When the speed difference information drops below a predetermined level, a servo control circuit 15 resets the counter 5' by means of the falling of FG immediately thereafter. Since rising timing of the phase reference signal RP is the phase difference, shorter than one period, between the rising timing of FG and the clock CL, fluctuation of rotary speed of the motor 1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotation control device, and particularly to a rotation control device including a rotation speed control system and a rotation phase control system.

[Prior Art] FIG. 4 shows a conventional general configuration of a rotation control device that controls rotation speed and rotation phase. This conventional example is for adjusting the rotational speed and rotational phase of a capstan of a VTR to a desired target speed and phase.

In Fig. 4, 1 is a capstan motor that rotationally drives the capstan of the VTR, 2 is a rotational frequency detector that generates a speed detection pulse (FG) with a frequency proportional to the rotational speed of motor 1, and 4 is the FG. The speed control information (E
A speed detection circuit 5 outputs a phase reference signal (R) that indicates a reference phase using the clock of a reference clock generator 7.
6 is a phase detection circuit that outputs phase control information (EP) according to the phase difference between the phase reference signals PR and FG; 8 is the phase control information (EP)
and the speed control information (ES) to form rotation control information (CT);
) a control circuit that turns on and off the switch 12 according to
is a digital-to-analog (D/A>converter), and 11 is a drive circuit for driving the tram motor 1.

First, speed control will be briefly explained. Now, assuming that the time difference TE between the pulse edges of <FG is given as shown in FIG. 5, the rotational speed can be kept constant by making this time difference TE a constant value. For example, by counting the number of reference clocks between adjacent rising edges of FG, the above time difference TE can be calculated.
is obtained, and the function fs(TE) of the time difference TE can be set as the speed control information SE as shown in FIG. That is, when the time difference TE between the edges of the FG is large, that is, when the rotational speed is slow, the value of the speed control information ES becomes large and the rotational speed of the motor 1 increases. On the other hand, when the time difference TE is small, that is, when the rotation speed is high, the speed control information ES
The value of becomes smaller and the rotation speed decreases.

The speed detection circuit 4 outputs speed difference information SD from the target speed based on the information on the time difference TE, and the control circuit 9 turns on the switch 12 when the absolute value 1sDI of this speed difference information SD becomes equal to or less than a predetermined value TH. Perform phase control.

Next, phase control will be explained. The purpose of phase control is F
This is to ensure that the phase difference of the phase reference signal RP with respect to G is constant. For example, as shown in FIG. 7, the falling timing of FG and the rising timing of phase reference signal RP are made to match. Then, these time differences are defined as phase difference information PD, and a function fp (PD) of this PD is defined as phase control information EP according to FIG. FG as shown in Figure 7
When the falling timing of signal RP is delayed from the rising timing of signal RP, phase control information EP is increased according to the characteristics shown in FIG. 8, and phase difference information PD approaches O as shown in FIG. Also, the falling timing of FG is the signal RP.
If it is ahead of the rising timing of , the phase control information EP is made small, and similarly the phase difference information PD is controlled to approach O.

[Problems to be Solved by the Invention] However, in the conventional rotation control device as described above, after the rotation speed of the motor 1 reaches near a predetermined target speed according to the speed control information ES, when starting phase control, the FG It is not known what the phase relationship is between the phase reference signal RP and the phase reference signal RP. Therefore, it is possible that there may be a large phase difference between FG and phase reference signal RP at the start of phase control.
In this case, speed irregularities will temporarily occur in the rotational speed of the motor 1 at the start of phase control.

For example, when performing so-called splicing on a VTR, the tape is rewound a little before recording starts, and the recorded tracks are played back. The rotational phase control of the capstan motor at this time is performed, for example, by a tracking control signal (ATF signal) obtained from a pilot signal reproduced from a video head. When starting recording in this state, good continuous shooting can be achieved as long as neither the rotational speed nor the rotational phase is changed.

However, when performing phase control based on the phase difference between the reference phase signal RP and FG as described above, speed unevenness may occur in the rotation of the capstan motor, and due to this, the continuity of the track in the spliced portion may be affected. Disturbance occurs. Therefore, when this part was later played back, the playback image would be momentarily distorted.

In order to solve this kind of inconvenience, it is possible to increase the frequency of the FG, but due to physical limitations, the frequency of the FG cannot be made sufficiently high. That is, the occurrence of speed unevenness is an unavoidable problem in order to set the phase difference of half a period of FG to O.

The present invention has been made in view of the above-mentioned problems, and is a rotation control device capable of preventing the occurrence of rotation speed unevenness due to the existence of a phase difference between a rotation detection signal and a reference signal at the start of rotation phase control. The purpose is to provide

[Means for Solving the Problems] To achieve this purpose, the rotation control device of the present invention includes means for forming a rotation detection signal with a frequency proportional to the rotation speed of a rotating body, and a rotation detection signal using the rotation detection signal. a rotational speed control means for rotating the rotating body at a predetermined target speed; and a clock having a higher frequency than the rotation detection signal when the rotating body is rotating at the target speed is divided as a reference. a frequency dividing means for forming a signal; a rotational phase control means for rotating the rotating body so that the reference signal and the rotation detection signal are phase-synchronized; The apparatus is configured to include means for resetting the means using the rotation detection signal.

[Operation] By configuring as described above, the phase difference between the reference signal and the rotation detection signal at the time of starting the operation of the rotational phase control means is within one clock, and can be extremely small. As a result, speed unevenness no longer occurs at the start of rotational phase control.

[Example] Examples of the present invention will be described below.

FIG. 1 is a diagram showing the configuration of an embodiment in which the present invention is applied to a capstan control system of a VTR, and FIG. 2 is a timing chart for explaining the operation of FIG. 1.

Components in FIG. 1 that are similar to those in FIG. 4 are given the same numbers and their explanations will be omitted. In Figure 1, 13 is VT
14 is a system control circuit that controls the mote of the entire VTR according to the operation of the operation section 13; 15 is a system control circuit that controls the state of the capstan servo system based on information from the system control circuit 14 and speed difference information SD; A servo control circuit for controlling, 16 a switch for changing the phase control state, 17 an ATF circuit for forming an ATF signal using the reproduction signal of the rotary heads Ha, H, 18 an analog-digital (A/D)
The converter 19 is an AND gate.

When key operations such as recording, playback, and pause cancellation are performed on the operation unit 13, the system control circuit 14 transmits motor start/stop information (S/S) and record/playback mote information (R/P) to the servo control circuit. 15.

When a motor stop command is given, the servo control circuit 15 sets the motor stop command ST to high level and connects the switch 16 to C. When the stop command ST is at a high level, the speed detection circuit 4 sets the speed control information ES to 0, and since the phase control information EP also becomes 0, the motor drive information CT
becomes O, and the motor 1 is stopped.

With the start of recording or playback, start/stop information (S/S
) is manually applied to the servo control circuit 15, the circuit 15 sets the stop command ST to low level, the speed detection circuit 4 outputs the speed control information ES according to the characteristics shown in FIG.
Speed control is started. However, immediately after starting the motor 1, the switch 16 is connected to C regardless of recording/reproduction, and no phase control is performed.

When the rotational speed of the motor 1 approaches the target speed and the absolute value l5D1 of the speed difference information exceeds the predetermined value 78, the switch 1
6 is connected to the P terminal during recording and R1 during reproduction according to the recording/reproduction mode information (R/P).

Phase control during reproduction is performed by using information AT obtained by digitizing the ATF signal from the ATF circuit 17 with the A/D converter 18 as phase control information EP. ATF circuit 1
As 7, for example, a circuit according to the well-known four-frequency power equation can be applied.

On the other hand, phase control during recording is performed using phase control information EP formed according to the phase difference between phase reference signal RP and FG, which are obtained by frequency-dividing the output clock CL of clock generator 7 by counter 5'. The counter 5' counts the clock CL and outputs its carry signal as a phase reference signal.

For example, when a 4-bit counter is used as the counter 5', the frequency of the reference clock CL is set to 16 times the frequency of the FG at the target speed.

When starting phase control using the output of the phase detection circuit 6, that is, when the absolute value l5D1 of the speed difference information becomes less than a predetermined value at the start of recording, and when the device switches from playback mode to recording mode during continuous shooting. The servo control circuit 15 resets the counter 5' at the falling timing of FG immediately after (as shown in FIG. 2, X). As a result, as shown in FIG. 2 RP, the rising timing of the phase reference signal RP immediately after this has a phase difference of less than one period of the clock CL from the falling timing of FG, and the phase control signal output from the phase detection circuit 6 is controlled. The information becomes almost 0. Therefore, the rotational speed of the motor 1 will not be uneven due to this phase control information EP.

According to the above-mentioned configuration, good recording can be performed without causing speed irregularities in the motor at the start of phase control using the FG and the phase reference signal RP. Therefore, during continuous shooting, phase control is changed from control by ATF signal to FG and phase reference signal R.
Even if control is switched to control based on the phase difference of P, the continuity of the track will not be impaired.

In the above embodiment, the frequency of the phase reference signal RP was set to be the same as that of FG when rotating at the target speed, but FG was set to 1/n of FG when rotating at the target speed.
A similar effect can be obtained by using a configuration in which the phase is controlled based on the phase difference with the signal divided by /n. In this case, the frequency dividing circuit of the clock CL may be reset using this frequency divided signal.

In addition, the reset of the counter 5' is performed using FG and the phase reference signal R.
It is also possible to adopt a configuration in which phase control is always performed during a period when phase control is not performed using P.

Processing of control information of the rotation control device configured as described above can be realized by software using a processor such as a microcomputer. In particular, in a device that monitors the rotational control status and changes the information processing characteristics as in the above embodiment, the hardware tends to be large, so it is advantageous to use software to perform most of the processing of the control system. It is.

FIG. 3 is a flowchart illustrating the operation of the computer when the area indicated by the broken line Y in FIG. 1 is replaced by a microcomputer.

Start of motor drive from system control circuit 14.13/
When the stop signal (S/s) is manually input (step S1)
In steps 32 to S4, the process transitions to a processing standby state in which it waits for input of each signal.

In this state, every time the internal clock in the microcomputer is generated (step S2), the time information T is updated (step S5). This internal clock is the reference clock C
Also used as L.

That is, 1 is added to the variable CU in step S6 for each manual power of this clock, and when this variable CU exceeds a predetermined number X (step S7), this variable CU is reset to 0 (step S8), and the phase reference timing information The time T is set in PR (step 59), and the process returns to the IA processing standby state. On the other hand, if the variable CU is less than X, the process returns to the processing standby state from step S7.

Also, every time the FG is manually operated from the rotational frequency detector 2 (
In step S3) and steps S10 to S22, the output control information CT is updated in conjunction with the update of the speed control information ES and phase control information EP.

This operation will be briefly explained below.

First, step 510) sets the time T at which the FG was manually operated to a variable TR indicating the current FG's manually operated time.
The manual time TP of the previous FG is subtracted from , and the time difference between them is calculated and placed in the time difference information TE (step 511). The speed difference information SD between the rotational speed and the target speed is given by the function f, (TE) of this time difference information TE, so SD is given by f,
(TE) is set (step 512). Further, since the speed control information ES is also given as a function f of this time difference information TE, f.

(TE) is placed in ES (step 513).

However, when performing processing corresponding to a loop filter for speed control, f, (TE) may be accumulated for a predetermined period as speed error information SE, and ES may be obtained by calculating this.

Here, if the absolute value f, 1sD1 of the speed difference information is greater than or equal to a predetermined value (step 514), phase control is not performed and the phase control information EP is set to 0 (step 515), and the variable CU
is reset to 0 (step 318). Also, during playback, phase control is performed using the ATF signal, so if the playback mode is (step 516), the ATF signal is included in the phase control information EP.
The information AT is set at step 517), and the variable CU is reset to 0 (step 818).

When the rotational speed almost matches the target speed and the recording mode is in effect, that is, when the absolute value l5DI of the speed difference information is less than the predetermined value (
Step 514) and recording mode (Step 5
16) Perform phase control using FG and the above phase reference timing. In this case, first, in step S19, the phase difference information P
D is set by subtracting the phase reference timing information PR from the FG manual time TR. Then, phase control information EP is calculated based on this phase difference information (step 52
0).

Thereafter, the updated speed control information ES and phase control information EP are added to update the output control information CT (step 511). Thereafter, the current FG input time TR is set as the previous FG input time, TPk is set (step 12), and the process returns to the processing standby state.

In the processing standby state, when a stop of recording or playback is given from the operation unit 13 as an S/S manual operation (step S4).
), the output control information CT is immediately set to 0, and the rotation of the motor 1 is stopped (step 523).

Even in software processing using the above-mentioned microcomputer, except when performing phase control using FG,
Variable C used to determine reference phase timing by FG
U is reset to 0, and the reference phase signal is schematically the second
As shown in FIG. RP', the same effect as the device shown in FIG. 1 can be obtained.

[Effects of the Invention] As described above, according to the present invention, it is possible to prevent rotational speed unevenness from occurring at the start of rotational phase control according to the phase difference between the rotation detection signal and the reference phase signal. A control device is obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an embodiment in which the present invention is applied to a rotating cylinder control system of a VTR, Fig. 2 is a timing chart for explaining the operation of Fig. 1, and Fig. 3 is the same as that of Fig. 1. A flowchart showing the operation when the processing within the dashed line is performed by software processing of a microcomputer. Fig. 4 is a diagram showing an example of the configuration of a conventional rotation control device. Fig. 5 shows the rotation speed control by the device in Fig. 4. 6 is a characteristic diagram showing changes in speed control information by the device in FIG. 4; FIG. 7 is a timing chart to explain rotational phase control by the device in FIG. 4; The figure is a characteristic diagram showing changes in phase error information by the apparatus of FIG. 4. In the figure, 1 is a motor, 2 is a rotation speed detector, 4 is a speed detection circuit, 5' is a counter as a frequency divider, 6 is a phase detection circuit, 7 is a clock generator, 8 is an adder, and 11 is a drive circuit, 14 is a system control circuit, 15 is a servo control circuit, 1
6 is a switch, and 17 is an ATF circuit.

Claims (1)

[Claims] means for forming a rotation detection signal having a frequency proportional to the rotation speed of the rotating body; rotation speed control means for rotating the rotating body at a predetermined target speed using the rotation detection signal; frequency dividing means for dividing a clock having a higher frequency than the rotation detection signal when the rotating body is rotating to form a reference signal; A rotation control device comprising rotational phase control means for rotating a body, and means for resetting the frequency dividing means with the rotation detection signal in response to the start of operation of the rotational phase control means.