JPH0265684A - Servo device - Google Patents

Abstract

PURPOSE:To obtain a satisfactory servo having no error by driving a mask circuit by the edge of a shaping signal for a predetermined period of time. CONSTITUTION:A drive signal is supplied from a microcomputer 1 to a motor 3 through a drive amplifier 2. A frequency generator 4 is provided in the motor 3, and this output signal is shaped by a FG amplifier 5 and supplied to the FG input of the microcomputer 1. When a rising edge is, for example detected at the FG input, a signal of the range of the time T1 of a noise mask timer is masked, and the edge by a noise is removed. The time T1 of the timer satisfies T1<T2, where the duration of the rising edge of the FG input at the time of a normal operation is T2, and it is determined according to the width, mixing place of the noise to be mixed, the overshoot of a servo, etc. Since the signal within a predetermined period of time from the edge is masked in this manner, a noise component generated during this period is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a servo device applied to, for example, a drum motor of a small-sized VTR with an integrated camera.

[Summary of the invention]

In a servo device, the present invention shapes a signal from a frequency generator, drives a mask circuit with the edges of this shaped signal, and uses this mask circuit to remove noise components, so that good servo is always performed. It is meant to be.

[Conventional technology]

For example, when downsizing a VTR such as a camera-integrated VTR, it is particularly important to downsize the drum motor that drives the rotating head drum. That is, FIG. 4A shows the configuration of a downsized motor and drum, (41) is a fixed drum,
(42) is a rotating drum;
) is provided with a magnet (43) on the end face thereof, and a fixed drive coil (44) as shown in FIG. And this drive coil (
44) sequentially it? By flowing *, the magnet (43) and the rotating drum (42) are rotated.

By the way, in a drum motor, it is necessary to perform servo control for rotation of the motor. Therefore, a detection coil (45) for the frequency generator as shown in FIG.
Here, in the above-mentioned configuration, the magnet (43) for the drive and frequency generator is used for the purpose of miniaturization, and therefore the drive coil (44) and the detection coil (45) are provided extremely close to each other. become.

However, for example during startup, the drive coil (44)
When a large current is passed through the shield plate, the effect of the shield plate is not sufficient, and since the frequency changes during startup, it is difficult to remove it with a filter.

This application was filed in view of these points.

[Problem to be solved by the invention]

However, as described above, when the drive coil (44) and the detection coil (45) are provided close to each other, an electromotive force is generated in the detection coil (45) due to the current flowing through the drive coil (44). There is a risk that noise may be mixed into the detection signal. Such noise generally acts to increase the frequency of the detection signal, thereby causing servo errors and the like.

Such noise can be removed, for example, by inserting a shield plate between the coils during normal operation, or by providing a filter in the servo circuit.

[Means to solve the problem]

The present invention uses a frequency generator installed close to the drive coil of the motor (3) to shape the signal from 41 (FG amplifier (51) L), and uses the edges of this shaped signal to control the speed servo of the motor. In the servo device (microcomputer (1)), the edge of the shaping signal drives a mask circuit for a predetermined period of time (step (2)) L. This mask circuit is mixed into the signal from the frequency generator. This is a servo device that removes (step [1]) noise components generated by the current flowing through the drive coil.

[For production]

According to this, since signals within a predetermined time from the edge are masked, noise components generated during this period are removed, thereby allowing good error-free servo to be performed.

〔Example〕

FIG. 1 shows the structure of the system. In this figure, a drive signal (servo output) from a microcomputer (μCOM) (11) serving as a servo device is supplied to a motor (3) through an error amplifier and a drive amplifier (2). (4) is provided, and this output signal is shaped by an FG amplifier (5) and supplied to the FC input of the microcomputer +11.

In the microcomputer fil, when a rising edge, for example, is detected in the FC input, the routine of the flowchart shown in FIG. 2 is started.

In this figure, in step [1] it is determined whether the value of the noise mask timer (t >1"). If the answer is normally no, then in step [2] the value of the noise mask timer is determined. The value [ is set to t-Q, servo processing is performed in step [3], and the routine ends.On the other hand, if step (1) is YES, this edge is determined to be noise. The routine is ended without performing any servo processing.The above-mentioned noise mask timer measures a predetermined time regardless of the FC input or the operation of the routine.

Therefore, if the above-mentioned frequency generator (4) outputs a signal as shown in FIG.
When supplied to the G amplifier (5), shaping is performed as shown in FIG. Conventionally, when this signal is used for servo processing, servo is performed at the rising edge as shown in C in the same figure.For example, if there is noise as shown in ■ in the figure, the edge is frequency doubled, causing a servo error.

In contrast, in the above-mentioned device, the noise mask.

The timer masks the number (i) in the range of time T1 shown in the same figure, and edges due to noise are removed as shown in the same figure, making it possible to perform good servo processing.

The time T of the above-mentioned noise mask timer satisfies T + < T z, where T2 is the interval between rising edges of the FC input during normal operation, and the width of the noise mixed in, the location of the noise mixed in, and the servo This is determined by taking into consideration overshoot, etc., but the location where it is mixed can be placed near the FG large input rising edge, for example, depending on the design of the drive coil (44) and detection coil (45).

In addition, if the design is made in the vicinity, noise is a natural problem.

However, since the servo processing at startup, for example, is a problem only with respect to the FG large input frequency, slight fluctuations in phase do not pose a problem.

In this way, according to the above-mentioned apparatus, since signals within a predetermined time from the edge are masked, noise components generated during this period are removed, thereby making it possible to perform good servo without errors.

In addition, since the main operation of the above-mentioned device is performed by microcomputer software, there is no need to add new circuit components, and material/processing costs and space factors do not deteriorate.

〔Effect of the invention〕

According to this invention, since the signal within a predetermined time from the edge is masked, noise components generated during this period are removed, thereby making it possible to perform good servo without errors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an example of the present invention, FIGS. 2 and 3 are diagrams for explaining the same, and FIG. 4 is a block diagram of a drum and a motor. (11 is a microcomputer, (2) is a drive amplifier, (3) is a motor, (4) is a frequency generator, and (5) is an FG amplifier.

Claims (1)

[Claims] A servo device that shapes a signal from a frequency generator disposed close to a drive coil of a motor, and uses edges of the shaped signal to servo the speed of the motor. A servo device that drives a mask circuit for a predetermined time at an edge, and uses this mask circuit to remove a noise component generated by a current flowing through the drive coil and mixed into a signal from the frequency generator.