JPS6224470A - Electronic still camera - Google Patents

Abstract

PURPOSE:To shorten a time of phase fluctuation by rotating a motor uniformly independently of load fluctuation when a magnetic head is moved to another recording track, and reducing the amount of phase fluctuation when may be generated then. CONSTITUTION:In a speed control system 20, the output frequency of an FG 9 is converted to a voltage by an F/V 21 and this voltage is amplified by a phase compensating amplifier 23 to drive a motor 12 through an adding circuit 24, and the rotation frequency is kept constant. In a phase control system 25, the signal from a vertical synchronizing signal circuit 26 and the signal from a tack 7 are compared with each other by a phase comparing circuit 27, and the output of this circuit 27 passes a phase compensating amplifier 28 and is added to the output of the speed control system 20 by an adding circuit 24, and relations between a recording signal switching point and a vertical synchronizing signal recording position are kept. An adding circuit 22 is provided, and the pulse which drives a pulse motor driving circuit 18 is not only applied to a pulse motor 19 but also added to the speed control system 20, and the voltage applied to the motor is raised to increase temporarily the driving torque when the head is moved to another track.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a motor servo circuit for an electronic still camera, and in particular, to a motor servo circuit for an electronic still camera, which is capable of suppressing the amount of phase fluctuation due to motor load fluctuation when moving a head and changing recording tracks. This relates to electronic still cameras.

[Background of the invention]

Conventional motor servo circuits for video equipment were developed in Japanese Patent Application Laid-open No. 58
As shown in Publication No.-22588, etc., it had a speed control system and a phase control system.

It is well known that in such a control system, variations in speed control appear as variations in phase control. Electronic still cameras use a similar control method; when the magnetic head is moved and the recording track is changed, the motor load changes temporarily, the operating points of the speed control system and phase control system change, and the phase The lock position has changed. Conventionally, no consideration was given to countermeasures against this point. This phenomenon is particularly problematic when continuous recording is performed with an electronic still camera. Continuous recording operation is an operation in which the head is moved at a high speed and the recording trunk is changed.

This speed is selected to be about 5 to 6 times per second for various reasons (the speed is mostly determined by the shutter response speed of the optical system).

In other words, the time required for one track is about 200 m5. However, due to the characteristics of the phase control system, it takes about 400 m5 for the phase to settle to the locked position after motor load fluctuations, that is, track movement, due to the characteristics of the phase control system. It was affected by the response of the servo system, and was about 2 RO per second, which was a big problem.

There is also a problem when continuously recording television signals, and the speed of continuous recording is determined by the head movement speed and the stabilization time of the phase control system. It took 400 m5, and only two bacterial species could be recorded per second.

The track movement time of the head varies depending on the configuration of the head movement mechanism system, but in the case of an electronic still camera, it is approximately 4.
It is selected from 0 to 70n+s. Note that this moving time can be further shortened by changing the head moving mechanism.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic still camera equipped with a motor servo circuit that eliminates the drawbacks of the prior art described above and reduces the amount of phase fluctuation and the time of phase fluctuation during track movement.

[Summary of the invention]

The main point of the present invention is to focus on the fact that the cause of the phase fluctuation when moving the trunk is the motor load fluctuation, and that this phenomenon only occurs when the truck is moving.
In order to keep the rotation of the motor constant, pulses are applied to the speed control system, thereby reducing the amount of phase fluctuation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3(a) shows a plan view of the magnetic sheet peripheral mechanism of the electronic still camera, and FIG. 3(b) shows a side view.

1 is a magnetic sheet, 2 is a hub, 3 is a PG point (reference position for recording), 4 is a motor boss, 5 is a video signal, 6 is a vertical synchronization signal leading edge, 7 is a tack coil, 8 is an adsorption magnet , 9 is an MR element, 10 is a recording signal switching point, 11 is an FG magnetized belt, 12 is a motor, 13 is a pad,
14 is a magnetic head, 15 is a head moving mechanism, and 16 is a pulse motor. The magnetic sheet 1 is attached to the hub 2,
It is attached to the boss 4 of the motor 12 by being attracted by the attraction magnet 8. The rotation of the motor 12 is carried out by detecting changes in the magnetic pole of the FG magnetized band 11 using the MR element 9. Also, a part of the KPG point 3 of the hub 2 is bent, which is detected by the tack coil 7 and used as a tack signal. According to the electronic still camera standard, a point K is included in the video signal 5, which is advanced by ZH±2H (H is the horizontal scanning period, or approximately 63.5 ms) from the signal switching point 1o drawn at the position of the PG point 3. It is standardized to record so that the leading edge 6 of the vertical synchronization signal is positioned. With 13-ke pad,
It functions to maintain stable contact between the magnetic sheet 1 and the magnetic head 14. When the pulse motor 16 rotates, the magnetic head 14 moves via the head moving mechanism 15.

The configuration of such an electronic still camera has the above-mentioned problems.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 17 is a system control, 18 is a pulse motor drive circuit, 20 is a speed control system, and a frequency-voltage conversion circuit (hereinafter abbreviated as F/V) 21
, an adder circuit 22, and a phase compensation amplifier 23.

24 is an adder circuit, 25 is a phase control system, and phase comparison circuit 2
7. Consists of a phase compensation amplifier 28. The system control 17 functions to control the overall operation of the electronic camera. Generally, part of the operation using a microcomputer includes the operation of driving the pulse motor 19 in order to move the head to track. The pulse motor 19 is powered by power t7'c, and a pulse is applied to the pulse motor drive circuit 18.

20 is a speed control system), and the output frequency of FG9 is F/
1721 converts it into a voltage, amplifies it with a phase compensation amplifier 23, drives the motor 12 via an adder circuit 24, and drives the motor 1.
Keep the rotation speed of 2 constant. A phase control system 25 compares the signal from the vertical synchronization signal circuit 26 with the signal from the tack 7 in a phase comparator circuit 27, and then compares the signal with the speed control system 20 in an adder circuit 24 via a phase compensation amplifier 28. As shown in FIG. 3, the recording signal switching point 10 and
The relationship with vertical synchronization signal recording position 6 is maintained.

Here, in order to change the recording track, pulse motor 1
9 and moves the magnetic head, a pulse-like load is temporarily applied.

This situation is shown in FIG. 2A (a) or FIG. 2B (a).

Note that FIGS. 2A and 2B are operational waveform diagrams of each part in the circuit of FIG. 1, and FIG. 2A shows the case where the present invention is not implemented, and FIG. 2B shows it when the present invention is implemented.

As a result, the output of the speed control system 20 changes, and the phase control output of the speed control system 25 also changes, and the above-mentioned recording signal switching point and
The relationship between vertical synchronization signal recording positions changes.

Therefore, in the present invention, the speed control system 20 includes an adder circuit 22 t
[lt. Apply pulses to drive the pulse motor drive circuit 18 to the pulse motor and speed control system 2
When moving the trunk, the voltage applied to the motor is increased to temporarily increase the drive torque.

In the case of an electronic still camera, the track moving speed is constant and the amount of change in load is also almost constant, so the width of the pulse added to the speed control system 20 (the width of the pulse (the height of the pulse corresponds to the amount of change in speed) is almost constant). good.

Specifically, for example, it is conceivable to attach a monostable multivibrator as shown at 29 in FIG. The output of the monostable multivibrator 29 is shown in (b) in Figure 2B.
The waveform is shown below. The height of this pulse is, for example, the power supply voltage v
Set it to 0°. The width of this pulse is determined experimentally by measurement, and is made so that the amount of phase fluctuation is as small as possible. By doing so, the phase error signal (indicating the amount of phase fluctuation) becomes extremely small (see Fig. 2B) compared to the conventional method (see Fig. 2A) that does not include the addition from (b), and the phase pull-in time can also be shortened.

For more detailed control, the width of the pulse applied to the speed control system 20, the waveform per hour, etc. may be changed. Another possible method is to change the applied pulse depending on the position (inner circumference/outer circumference) of the magnetic head.

〔Effect of the invention〕

As described above, according to the present invention, the amount of phase fluctuation that occurs when the magnetic head moves along the recording track can be reduced, and the phase fluctuation time can also be shortened, so that electronic still cameras can achieve faster continuous recording. became possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. 2A and 2B are operation waveform diagrams of each part in FIG. 1, FIG. 2A is a waveform diagram showing the case where the present invention is not implemented, FIG. 2B is a waveform diagram when the present invention is implemented, and FIG. 3(a) 3(b) is a plan view showing the configuration of a magnetic sheet and a mechanical section around the magnetic head of an electronic still camera, and FIG. 3(b) is a side view of the same. Explanation of symbols 1... Magnetic sheet 9... MR element 7... Tank 12... Motor 17... System control 20...・・・
・Speed control system 25... Phase control system 22... Addition circuit 29... Monostable multi-noise ibrator~\

Claims (1)

[Claims] 1) Vertical synchronization of a motor that rotationally drives a magnetic sheet, a speed control circuit that controls the rotational speed of the motor to be kept constant, and a video signal that records an arbitrary specific position on the magnetic sheet. In addition to a motor servo circuit configured with a phase control circuit that controls the motor to match the position of the signal, a magnetic head that records and reproduces video signals on the magnetic sheet, and a magnetic head that records and reproduces video signals on the magnetic sheet. In an electronic still camera equipped with a head moving mechanism for track movement on a sheet, when the magnetic head movement mechanism is driven to move the magnetic head on a track on the sheet, the drive signal for this is controlled by the speed in the speed control circuit. An electronic still camera characterized in that the electronic still camera is equipped with a means for adding it to a control signal so that the motor speed does not fluctuate regardless of load fluctuations caused by track movement of a magnetic head.