JPS61189179A - Servo circuit of motor - Google Patents

Abstract

PURPOSE:To shorten a time from the start of a motor to arrive to a normal rotation by bringing the frequency of a detection signal into coincidence with that of a reference signal and then bringing the phase in coincidence. CONSTITUTION:A motor drive circuit 2 for driving a motor 1 is connected with the motor 1, and the rotating speed of the motor is detected by a frequency generator (FG) 3. A speed control system 4 for controlling the rotating speed of the motor and a phase control system 5 for controlling the rotating phase by the output of the FG 3 are connected with the circuit 3. The frequencies of the output signal of the FG 3 and the horizontal synchronizing signal from horizontal synchronizing signal generating means 9 are brought in coincidence by the system 4, and the phases are then brought in coincidence by the system 5.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a motor servo circuit for a video signal recording/reproducing device such as an electronic still camera, and particularly relates to a motor servo circuit for a video signal recording/reproducing device such as an electronic still camera. The present invention relates to a preferred motor servo circuit.

[Background of the invention]

Conventional motor servo circuits for video equipment were developed in Japanese Patent Application Laid-open No. 58
-22588 etc., it has a speed control system and a phase control system. As a reference signal for this phase control system, a 60 Hz signal which is a vertical synchronizing signal of a video signal, or a 301 (z signal) obtained by frequency-dividing the 60 Hz signal is used.

In these conventional devices, the recording or playback command is issued while the motor is rotating steadily, so the time from motor startup to reaching steady rotation is not a big problem. It usually takes about 3 degrees.

However, in electronic still cameras, recording must be completed at the same time or within a fraction of a second after the shutter button is pressed. Particularly in the case of continuous photography in which several pictures are recorded per second, it is an important issue to shorten the time from motor startup until steady rotation is reached.

Furthermore, as lower power consumption of electronic still cameras becomes an issue in the future, this problem will become particularly important if a system is adopted in which the motor is driven only during photographing.

[Purpose of the invention]

An object of the present invention is to provide a servo circuit for a motor that can shorten the time from motor startup to steady rotation.

[Summary of the invention]

The present invention provides frequency matching means for matching the frequencies of two signals, the output signal of a frequency generator that detects the rotational speed of the motor, and the horizontal synchronization signal from the horizontal synchronization signal generation means, and this frequency matching means allows the frequency The above 2 matches
The above objective is achieved by performing phase control so that the phases of the two signals match.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention.

The motor 1 rotates a magnetic sheet (not shown) attached to a motor shaft. A motor drive circuit 2 for driving the motor 1 is connected to the motor 1, and the rotation speed of the motor 1 is detected by a frequency generator (hereinafter referred to as FG) 3. Connected to the motor drive circuit 2 are a speed control system 4 that controls the rotational speed of the motor based on the output of the FG 3, and a phase control system 5 that controls the rotational phase.

The speed control system 4 includes a frequency-voltage converter (which receives the output signal of F'G3 and converts the frequency signal into a voltage level signal).
It is written as F/V converter. ) 6° and a phase compensation type amplifier 7 for amplifying the output of the F/V converter 6.

The phase control system 5 divides the output signal of FG3 into 1/2.
/2 frequency divider circuit 8, 173 frequency divider circuit 10 which divides the frequency of the horizontal synchronization signal from the horizontal synchronization signal generation circuit 9 by 1/3, and 1/2 frequency divider circuit 8;
A phase comparator circuit 11 receives the output signals of the divide-by-2 circuit 8 and the divide-by-third circuit 10 and outputs a signal according to the phase difference between the two signals, and a phase comparator circuit that amplifies the output signal of the phase comparator circuit 11. It consists of a compensation type amplifier circuit 12.

The phase control system 5, which is a feature of the present invention, will be explained.

FG3 outputs a signal with a frequency of 10.5 K' Hz when the first motor is rotating in a regular manner. This signal is frequency-divided by a 172 frequency divider circuit 8 to obtain a 5.25 KHz signal. On the other hand, the horizontal synchronizing signal input terminal 13 has 15
．． A 75 KHz horizontal synchronization signal is input.

The 1/3 frequency divider circuit 10 divides the horizontal synchronizing signal to 5.25.
Obtain a KHz signal. The phase comparator circuit 11 divides the frequency-divided signal from FG3 and the frequency-divided horizontal synchronization signal.
The horizontal synchronization signal is a reference signal for the video signal, Using a crystal oscillator, it maintains an accurate frequency so that it has no temperature characteristics or changes over time. Therefore, the motor 1 is subjected to so-called PLL control.

Here, the 1/2 frequency divider circuit 8 and the 115 frequency divider circuit 10
The G-times signal and the horizontal synchronization signal are frequency-divided by the phase comparator circuit 1 in order to perform phase comparison in the phase comparator circuit 11.
This is to match the frequency of the direct input signal input to 1.

Therefore, if the frequency of the signal generated during steady rotation in FG3 is set to a different value, the frequency of the input signal to the phase comparator circuit 11 must be matched by changing the frequency division ratio of these frequency divider circuits. Must be. In this example,
The frequency of the output signal of FG3 is determined by 1 from the mechanical precision of FG3.
Although the frequency is set to 0.5 KHz, it is also possible to set it to a higher frequency with improved mechanical precision. In this case, F
G frequency 15.75KHz, 31.5KHz
By setting the frequency to an integral multiple of the frequency of the equal horizontal synchronizing signal, the configuration of the circuit for matching the frequency of the input signal of the phase comparator circuit 11 becomes simple.

According to this embodiment, phase control was performed using the vertical synchronization signal of 6011z as a reference signal, but the phase control is now 5.25K.
Since phase control is performed using a signal with a high frequency of Hz as a reference signal, the time required to reach a phase-locked state where the phase is stable can be significantly shortened.

Furthermore, the FG frequency is changed to the vertical synchronization signal frequency of 60Hz (
The effects of the present invention can be obtained by setting the frequency to 5x s x 3 x 7/2). For example, 6
1050H which is 5X5X7 frequency of 1/2 of 0Hz
It is clear that by setting the FG frequency to z, dividing the horizontal synchronizing signal by 15 and comparing the phases, it is possible to shorten the phase pull-in time compared to the conventional case where the phases are compared at 60 Hz.

Furthermore, although the horizontal synchronization signal is used as the reference signal, in many cases, electronic cameras and the like already have a horizontal synchronization signal generation section in the imaging section, etc., and there is no need to provide a new horizontal synchronization signal generation circuit.

Next, in order to further clarify the effects of the present invention, a case where the motor servo circuit of the present invention is applied to an electronic still camera will be described.

FIG. 2 is an overall configuration diagram of an electronic still camera to which the present invention is applied. The motor 1 includes the aforementioned motor servo circuit 2.
0 is connected. A magnetic disk 2 is attached to the shaft of the motor 1.
1 is attached, and a magnetic head 22 is in contact with the magnetic disk 21. A recording circuit 23 is connected to the magnetic head 22 .

The imaging device 24 is connected to the recording circuit 23 via a recording gate circuit 25. The imaging signal generation circuit 27 generates horizontal and hydroperitoneal synchronization signals using the crystal 28, and the imaging device 24. Supplied to the motor servo circuit 2o. The system controller 26 controls the recording gate 25 . by the output of the motor servo circuit 20 and the signal from the shutter button 29 . Controls the imaging signal generation circuit 27. 3 is an FC generator, and 15Fi is a tack signal generation circuit.

FIG. 4(a) shows a plan view of a magnetic sheet of an electronic still camera, and FIG. 4(b) shows a side view.

21 is a magnetic sheet, 31 is a hub, 32 is a PC point,
36 is the boss of the motor, 34 is the video signal, 35 is the leading edge of the vertical synchronization signal, 37 is the tack coil, 38 is the adsorption magnet, 39 is the MR element, 36 is the recording signal switching point), 4
This is a 0FiFG magnetized band. The magnetic sheet 21 is attached to the hub 31 and is attracted to the boss 36 of the motor 1 by an attraction magnet 68, and the rotation of the attached motor 1 changes the magnetic pole change of the 4o FG magnetized belt by the MR element 39. Detect and retrieve. Further, there is a PG point 32 in a part of the hub 31, which guides the magnetic force of the attraction magnet 38, which is detected by the tack coil 37 and used as a tack signal. In addition, the standard for electronic still cameras is 32 PG.
From the 56 signal switching points drawn at the point positions,
7H±2H (H is in the horizontal synchronization signal, 1H is 67.
It is 5 μS. ) included in the 19 video signals between
It is determined that recording is performed so that the leading edge of the vertical synchronization signal shown in 5 is positioned.

In FIG. 2, 15 is a tack coil, which is the same as the tack coil 67 in FIG.

The motor servo circuit 20 performs the rotational speed control and phase control described in FIG. 1 using the output signal of the tack coil 15, the FG generator 3, and the signals from the imaging signal generation circuit 27. Further, the motor servo circuit 20, when the phase comparison output shown in FIG. 11 becomes below a certain signal level,
It is determined that the phase control has entered a stable control state, and a phase lock signal C is output. This phase lock signal is then supplied to one input terminal of the AND circuit 30. The output signal of the tack coil 15 is directly supplied to the other input terminal of the AND circuit 30 as a signal shown at D. The operation of this embodiment will be explained using the timing diagram shown in FIG.

When the shirt button 29 is pressed at t=to, the motor 1 starts rotating and increases its speed. The motor 1 reaches steady rotation at tl, the phase lock signal rises at t=t2, and one input terminal of the AND circuit 60 is kept at the 'H' level. When t=ta, the tack signal becomes 'H'. In order to reach the level, the AND circuit 60 outputs a 'H' level signal. When the signal from the AND circuit 30 reaches the 'H' level, the system controller 26 supplies a vertical synchronization reset signal E to the imaging signal generation circuit 27. . This vertical synchronization reset signal resets the vertical synchronization signal F, and the vertical synchronization signal is set to a position shifted by a ratio H relative to the tack signal, as shown in FIG. 4(a).

At t=t4, the vertical synchronization reset signal changes to the 1H" level and the imaging unit [24 starts imaging at the next tack signal position. At the same time, the recording gate circuit 25 is opened, and the data is transferred from the imaging device 24 to the recording circuit 23. The video signals are sequentially read out and recorded on the magnetic sheet 21 by the recording head 22.

When recording is completed at t=t4, the supply of the drive signal to the motor 1 is stopped, and the motor 1 gradually decelerates and stops.

According to this embodiment, since the phase is locked using the horizontal synchronization signal, the time required for the motor 1 to phase lock is short, and there is no need to rotate the motor in advance before shooting with an electronic still camera. This can significantly reduce power consumption.

In addition, the quick start-up prevents the shirt turning from running out.

Note that the present invention can be used not only for electronic still cameras, but also for playback-only machines in which the imaging section of electronic still cameras is removed, and recording/playback machines that can record external video signals.
It can also be applied to other video signal recording devices that require quick start-up.

[Brief explanation of the drawing]

Figure 1 is a block diagram of one embodiment of the motor servo circuit of the present invention, Figure 2 is a block diagram of the motor servo circuit of the present invention applied to an electronic still camera, and Figure 3 is a block diagram of the circuit of Figure 2. The timing diagrams in FIGS. 4(a) and 4(b) are schematic diagrams showing the insertion state of the magnetic sheet. Explanation of symbols 1...Motor 2...Motor drive circuit 6...
・Frequency generator (FG) 4...Speed control system 5...
・Phase control system 6... Frequency-voltage conversion circuit 8...
1/2 frequency divider circuit 9...Horizontal synchronization signal generation circuit 10
...1/3 frequency divider circuit 11...phase comparison circuit 15.
...Tack signal generation circuit 17...Frequency matching circuit
20... Motor servo circuit 21... Magnetic disk 23... Recording circuit 24... Imaging device 25...
・Almost 1 record

Claims (3)

[Claims] (1) a motor that rotates a magnetic sheet, a frequency generator that detects the rotational speed of the motor, and a speed control circuit that maintains the rotational speed of the motor constant according to a frequency signal from the frequency generator; In a motor servo circuit of a video signal recording and reproducing device equipped with a magnetic head for recording or reproducing video signals on the magnetic sheet, horizontal synchronizing signal generating means used in video equipment, the horizontal synchronizing signal generating means and the frequency generator are provided. a frequency matching means for matching the frequency of the horizontal synchronizing signal from the horizontal synchronizing signal generating means and the frequency signal; and a phase for comparing the phases of the horizontal synchronizing signal and the frequency signal whose frequencies have been matched by the frequency matching means. 1. A motor servo circuit for a video signal recording and reproducing apparatus, comprising a comparison means and a phase control means for controlling the phase of the motor based on the output of the phase comparison means. (2) In claim 1, the video signal recording and reproducing device is characterized in that the frequency matching means includes frequency dividing means for dividing at least one of the horizontal synchronizing signal and the frequency signal into a predetermined frequency. Equipment motor servo circuit. (3) In claim 1, the horizontal synchronization signal generating means generates a horizontal synchronization signal of 15.75 KHz;
The frequency generator generates a frequency signal of 10.5 KHz in a steady state, and the frequency matching means includes a frequency dividing circuit that divides the frequency of the horizontal synchronizing signal by 1/3 and a frequency signal that divides the frequency signal by 1/2.
1. A motor servo circuit for a video signal recording and reproducing device, comprising a frequency dividing circuit.