JPH09269524A - Light quantity controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide compact and economical light quantity controller by installing a cylindrical rotor magnet, a driving coil arranged adjacent to the rotor magnet and a detecting coil in an actuator. SOLUTION: This light quantity controller 1 is provided with a motor part 2, a sine wave generating means 8, a resistance element 9, a high frequency pass filter(HPF) 10, a rectifying means 11, a smoothing means 12, a position error amplifier 13, a low frequency pass filter(LPF) 14 and a driving amplifier 15. And the motor part 2 is provided with a driving coil 3 for controlling the cylindrical rotor magnet 4, non-magnetic conductive foil 5 such as aluminium foil, or copper foil, etc., stretched on the outer circumferential curved surface of the rotor magnet 4, a detecting coil 6 arranged adjacent to the rotor magnet 4 and for detecting the rotational speed and position of the rotor magnet 4 and a spring 7 for working in a direction of closing an aperture blade, then, the aperture blade as a light quantity controlling member is opened/closed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light amount control device mounted on a video camera or the like.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a main part of a conventional light amount control device. In FIG. 4, the light quantity control device 60 includes a motor unit 61, a position detection amplifier 67, and a position error amplifier 68.
And a drive amplifier 69. The motor unit 61 also includes a drive coil 62, a rotor magnet 63, a speed detection coil 65, a hall element 64, and a spring 66.

The motor section 61 acts in the direction of closing the drive coil 62, the rotor magnet 63, the speed detection coil 65 for detecting the rotation speed of the rotor magnet 63, the hall element 64 for detecting the rotation angle of the rotor magnet 63, and the diaphragm blade. And a spring 66 that opens and closes the diaphragm blade that is a light amount control member.

The hall element 64 generates Hall electromotive forces S32 and S33 corresponding to the rotation angle of the rotor magnet 63 and outputs the Hall electromotive forces S32 and S33 to the position detection amplifier 67. The position detection amplifier 67 sets the Hall electromotive forces S32 and S33 to a predetermined voltage. Amplify and position signal S
34 is output to the position error amplifier 68. Position error amplifier 6
Reference numeral 8 compares and amplifies the position signal S34 and the target position signal S35, and outputs a position error signal S36 to the drive amplifier 69. The speed detection coil 65 generates a speed signal S31 which is an electromotive force (electromotive voltage) proportional to the rotation speed of the rotor magnet 63, and outputs the speed signal S31 to the drive amplifier 69.

The drive amplifier 69 outputs a drive signal S37 to the drive coil 62 based on the position error signal S36 and the speed signal S31 input to the inverting input terminal to output the drive signal S37 to the rotor magnet 6.
3 is controlled. The position error signal S36 input to the inverting input terminal of the drive amplifier 69 is a feedback signal for controlling the rotor magnet 63 so that the error from the target position becomes zero, and is input to the inverting input terminal of the drive amplifier 69. The speed signal S31 is a feedback signal for passing a current through the drive coil 62 so as to reduce the speed of the rotor magnet 63, braking the rotor magnet 63, and stabilizing the control system.

Further, as disclosed in Japanese Unexamined Patent Publication No. 6-95207, a drive coil, a rotor magnet, a speed detection coil for detecting the rotation speed of the rotor magnet, a hall element for detecting the rotation angle of the rotor magnet, and diaphragm blades are provided. There is known a rotation angle detection method that does not require a Hall element for detecting the rotation angle of a rotor magnet in order to simplify the structure of a motor unit including a spring that acts in the closing direction.

In the rotation angle detecting means disclosed in Japanese Patent Laid-Open No. 6-95207, a magnetic material piece is attached to a rotor magnet, and the mutual inductance between the drive coil and the speed detecting coil is a magnetic material piece accompanying the rotation of the rotor magnet. It is detected that it changes depending on the approach and separation of. The means for detecting the change in the mutual inductance superimposes an AC signal having a high frequency so that the rotor magnet does not respond to the drive voltage of the drive coil, and changes in the AC signal amplitude generated in the speed detection coil due to the change in the mutual inductance is detected as a voltage. The rotation angle of the rotor magnet is detected as a position signal, and the velocity signal is detected by differentiating the position signal.

[0008]

In the conventional light quantity control device shown in FIG. 4, since the hall element is used to detect the rotation angle of the rotor magnet, the structure of the motor part becomes complicated and the device size is reduced. There is a problem that it is not suitable for commercialization and the cost becomes high.

The rotation angle detecting means disclosed in Japanese Patent Laid-Open No. 6-95207 detects a change in mutual conductance due to approach and separation of magnetic material pieces as a position signal, but the rotor magnet itself is magnetized. Since it is a magnetic material, the mutual inductance between the drive coil and the speed detection coil is dominated by the effect of the rotor magnet, and the change in mutual conductance due to the approach and separation of the magnetic material pieces is small, resulting in low detection sensitivity and detection sensitivity. In order to increase the temperature, a large magnetic material piece may be attached, but the motor structure becomes large, which is not suitable for downsizing the device, and there is a problem that the cost becomes high. Further, since the velocity signal is obtained by differentiating the position signal, there is a problem that the noise component of the position signal is amplified by the differential operation and causes malfunction or unstable operation.

The present invention has been made in order to solve such a problem, and its object is to detect non-magnetic conductive foil on the outer peripheral curved surface of a rotor magnet and detect eddy current loss generated in the conductive foil. An actuator that opens and closes the diaphragm blade, which is a light quantity control member, by a position signal that detects the position of the rotor magnet by detecting with a coil and a speed signal that is an electromotive force (electromotive voltage) generated in the detection coil by the rotation of the rotor magnet is used. Drive control is possible,
An object is to provide a compact and economical light quantity control device.

[0011]

SUMMARY OF THE INVENTION A light quantity control device according to the present invention comprises a cylindrical rotor magnet having a non-magnetic conductive foil in an actuator, and a rotor magnet which is disposed close to the rotor magnet to rotate the rotor magnet. It is characterized by comprising a drive coil for controlling the position, and a detection coil which is arranged close to the rotor magnet and detects the rotational position and the rotational speed of the rotor magnet.

The light quantity control device according to the present invention comprises a cylindrical rotor magnet having a non-magnetic conductive foil, and a drive coil which is arranged close to the rotor magnet and which controls the rotational position of the rotor magnet. And a detection coil that is arranged close to the rotor magnet and detects the rotational position and the rotational speed of the rotor magnet.
The structure of the actuator can be simplified and downsized.

Further, the light quantity control device according to the present invention has a non-magnetic conductive foil on the outer peripheral curved surface of the rotor magnet,
The drive coil and the detection coil are arranged close to the curved surface of the outer circumference of the rotor magnet.

Since the light quantity control device according to the present invention has the non-magnetic conductive foil on the outer peripheral curved surface of the rotor magnet and the drive coil and the detection coil are arranged close to the outer peripheral curved surface of the rotor magnet, The structure of the actuator can be simplified and downsized.

Further, the light quantity control device according to the present invention is provided with a sine wave oscillating means for applying a sine wave signal to the detection coil, and the detection coil is provided with a change in the eddy current loss generated in the conductive foil of the rotating rotor magnet. It is characterized in that the rotational position of the rotor magnet is detected by the amplitude change of the applied sine wave signal.

The light quantity control device according to the present invention is provided with a sine wave oscillating means for applying a sine wave signal to the detection coil, and the light quantity control device is applied to the detection coil due to a change in eddy current loss generated in the conductive foil of the rotating rotor magnet. Since the rotational position of the rotor magnet is detected by the change in the amplitude of the sine wave signal, the rotational position of the rotor magnet can be detected with high sensitivity.

Further, the light quantity control device according to the present invention comprises sine wave oscillating means for applying a sine wave signal to the detection coil,
With the position signal of the rotor magnet that detects the amplitude change of the sine wave signal applied to the detection coil due to the change of the eddy current loss that occurs in the conductive foil of the rotating rotor magnet, and the electromotive force generated in the detection coil by the rotation of the rotor magnet. The rotor magnet is controlled to a predetermined position by a certain speed signal.

The light quantity control device according to the present invention is provided with a sine wave oscillating means for applying a sine wave signal to the detection coil, and the light quantity control device is applied to the detection coil according to the change of the eddy current loss generated in the conductive foil of the rotating rotor magnet. The position signal of the rotor magnet, which detects the amplitude change of the sine wave signal with high sensitivity, and the speed signal, which is the electromotive force generated in the detection coil by the rotation of the rotor magnet, enable stable and accurate position control of the rotor magnet.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments shown in the drawings. FIG. 1 is a block diagram of a main part of a light quantity control device according to the present invention. In FIG. 1, a light quantity control device 1 includes a motor unit 2, a sine wave oscillating means 8, a resistance element 9, a high pass filter (HPF) 10, a rectifying means 11, a smoothing means 12, a position error amplifier 13, and a low pass filter ( An LPF) 14 and a drive amplifier 15 are provided. The motor unit 2 also includes a drive coil 3, a rotor magnet 4, a conductive foil 5, a detection coil 6 and a spring 7.

The motor unit 2 is a non-magnetic conductive coil 5 such as a drive coil 3 for controlling the rotor magnet 4, a rotor magnet 4, and an outer peripheral curved surface of the rotor magnet 4, such as an aluminum foil or a copper foil. The aperture blades, which are light amount control members, are opened and closed by including a detection coil 6 that detects the rotational speed and position of the rotor magnet 4 and a spring 7 that acts in the direction of closing the aperture blades.

One end of the drive coil 3 is grounded and the other end is connected to the output of the drive amplifier 15. Sine wave oscillating means 8
Outputs a sine wave signal S1 having a predetermined amplitude value and frequency at a frequency sufficiently higher than the rotational operation response of the rotor magnet 4. The sine wave signal S1 of the sine wave oscillating means 8 is applied to one end of the detection coil 6 via the resistance element 9, and the other end of the detection coil 6 is grounded.

Therefore, in the detection coil 6, a sine wave signal S1 is applied to the detection coil 6 via the resistance element 9 with an electromotive force (electromotive voltage) proportional to the relative speed of the rotor magnet 4 and the detection coil 6. A detection coil signal S2 in which the wave signal is superimposed is generated.

Detection coil signal S2 appearing on the detection coil 6
The amplitude of the sine wave signal component of is changed by the relative distance between the conductive foil 5 and the detection coil 6. For example, as the relative distance increases, the eddy current generated in the conductive foil 5 decreases and the eddy current loss decreases, so that the amplitude of the sine wave signal component of the detection coil signal S2 appearing in the detection coil 6 increases.

On the contrary, if the relative distance is reduced, the eddy current generated in the conductive foil 5 increases and the eddy current loss increases, so that the amplitude of the sine wave signal component of the detection coil signal S2 appearing in the detection coil 6 decreases. . The conductive foil 5 is the rotor magnet 4
Is stretched on the outer peripheral curved surface of the rotor magnet 4, the relative distance between the detection coil 6 and the conductive foil 5 changes depending on the rotation angle of the rotor magnet 4, and depending on the rotation angle of the rotor magnet 4,
The amplitude of the sine wave signal component of the detection coil signal S2 appearing on the detection coil 6 changes.

Detection coil signal S2 appearing on the detection coil 6
Is input to the high-pass filter (HPF) 10, and the high-pass filter (HPF) 10 outputs the HPF signal S3 in which the low frequency component is attenuated from the detection coil signal S2 to the rectifying means 11. The rectifying means 11 outputs a rectified signal S4 obtained by rectifying the HPF signal S3 to the smoothing means 12, and the smoothing means 12 smoothes the rectified signal S4 to generate a baseband signal having a potential proportional to the rotation angle of the rotor magnet 3. , And outputs this baseband signal as the position signal S5 to the inverting input terminal of the position error amplifier 13. The position error amplifier 13 compares and amplifies the position signal S5 of the inverting input terminal and the target position signal S6 of the non-inverting input terminal and outputs the position error signal S7 to the inverting input terminal of the drive amplifier 15.

Further, the detection coil signal S2 appearing in the detection coil 6 is input to the low pass filter (LPF) 14, and the low pass filter (LPF) 14 receives the detection coil signal S2.
The high-frequency component is attenuated and an electromotive voltage component proportional to the relative speed of the rotor magnet 4 and the detection coil 6 is output to the inverting input terminal of the drive amplifier 15 as a speed signal S8.

The drive amplifier 15 outputs a drive signal S9 to the drive coil 3 based on the position error signal S7 and the speed signal S8 input to the inverting input terminal to control the rotor magnet 4. The position error signal S7 input to the inverting input terminal of the drive amplifier 15 is a feedback signal for controlling the rotor magnet 4 so that the error from the target position becomes zero, and is input to the inverting input terminal of the drive amplifier 15. The speed signal S8 is a feedback signal for passing a current through the drive coil 3 so as to reduce the speed of the rotor magnet 4, braking the rotor magnet 4, and stabilizing the control system.

As described above, the light quantity control device includes the motor unit including the drive coil, the rotor magnet, the conductive foil, the detection coil and the spring, the sine wave oscillating means, the resistance element, the high pass filter (HPF) and the rectifying means. It comprises a smoothing means, a position error amplifier, a low pass filter (LPF), and a drive amplifier, and can perform stable and accurate position control of the rotor magnet.

FIG. 2 is a block diagram of the essential parts of a light quantity control device according to the present invention. In FIG. 2, the light quantity control device 2
Reference numeral 0 denotes a motor unit 21, a two-phase sine wave oscillating means 27, a resistance element 28, a high-pass filter (HPF) 29, a synchronous rectifying means 30, a smoothing means 31, a position error amplifier 32, and a low-pass filter (LPF) 33. And a drive amplifier 34. The motor unit 21 also includes a drive coil 22, a rotor magnet 23, a conductive foil 24, a detection coil 25, and a spring 26.

The motor section 21 is a non-magnetic conductive foil 24 such as a drive coil 22 for controlling the rotor magnet 23, a rotor magnet 23, and an outer peripheral curved surface of the rotor magnet 23, which is, for example, an aluminum foil or a copper foil. And a detection coil 25 for detecting the rotational speed and position of the rotor magnet 23 and a spring 26 acting in the direction of closing the diaphragm blade to open and close the diaphragm blade which is a light amount control member.

One end of the drive coil 22 is grounded and the other end is connected to the output of the drive amplifier 34. The two-phase sine wave oscillating means 27 outputs a sine wave signal S11 having a predetermined amplitude value and frequency and a sine wave signal S20 advanced in phase by 90 degrees at a frequency sufficiently higher than the rotational operation response of the rotor magnet 23. The sine wave signal S11 of the two-phase sine wave oscillating means 27 is applied to one end of the detection coil 25 via the resistance element 28, and the other end of the detection coil 25 is grounded.

The detection coil 25 includes a rotor magnet 2
3 produces a detection coil signal S12 in which an electromotive force (electromotive voltage) proportional to the relative speed between the detection coil 25 and the detection coil 25 is superposed with a sine wave signal obtained by applying the sine wave signal S11 to the detection coil 25 via the resistance element 28. Since the phase of the detection coil signal S12 appearing in the detection coil 25 is composed of the series circuit of the resistance element 28 and the detection coil 25, the phase of the detection coil signal S12 is different from that of the sine wave signal S11.
8 is advanced by a phase determined by the resistance value of 8 and the inductance of the detection coil 25.

Similar to the principle of operation of the detection coil 6 and the conductive foil 5 described in the embodiment of the light quantity control device 1 of FIG. 1, the conductive foil 24 is stretched on the outer peripheral curved surface of the rotor magnet 23. The relative distance between the detection coil 25 and the conductive foil 24 changes depending on the rotation angle of the rotor magnet 23, and the amplitude of the detection coil signal S12 appearing in the detection coil 25 changes depending on the rotation angle of the rotor magnet 23.

Detection coil signal S appearing in the detection coil 25
12 is input to a high-pass filter (HPF) 29, and the high-pass filter (HPF) 29 attenuates the low-frequency component of the detection coil signal S12 to produce an HPF signal S13 which is synchronous rectifying means 30.
Output to The synchronous rectifying means 30 outputs the HPF signal S13 from the two-phase sine wave oscillating means 27 to the sine wave signal S11 by 90
The rectified signal S14 synchronously rectified by the sine wave signal S20 whose phase is advanced is output to the smoothing means 31.

The smoothing means 31 smoothes the rectified signal S14 to generate a base band signal having a potential proportional to the rotation angle of the rotor magnet 23, and the base band signal is used as the position signal S15.
Is output to the inverting input terminal of the position error amplifier 32.
The position error amplifier 32 compares and amplifies the position signal S15 of the inverting input terminal and the target position signal S16 of the non-inverting input terminal and outputs the position error signal S17 to the inverting input terminal of the drive amplifier 34.

The detection coil signal S12 appearing in the detection coil 25 is input to the low pass filter (LPF) 33,
The low pass filter (LPF) 33 detects the detection coil signal S.
Rotor magnet 23 by attenuating 12 high frequency components
And an electromotive voltage component proportional to the relative speed of the detection coil 25 is output to the inverting input terminal of the drive amplifier 34 as a speed signal S18.

The drive amplifier 34 outputs a drive signal S19 to the drive coil 22 based on the position error signal S17 and the speed signal S18 input to the inverting input terminal to output the drive signal S19 to the rotor magnet 2.
3 is controlled. The position error signal S17 input to the inverting input terminal of the drive amplifier 34 is a feedback signal for controlling the rotor magnet 23 so that the error from the target position becomes zero, and is input to the inverting input terminal of the drive amplifier 34. The speed signal S18 is a feedback signal for stabilizing the control system by passing a current through the drive coil 22 so as to reduce the speed of the rotor magnet 23 to brake the rotor magnet 23.

As described above, the light quantity control device includes the motor section including the drive coil, the rotor magnet, the conductive foil, the detection coil, and the spring, the two-phase sine wave oscillating means, the resistance element, and the high-pass filter (HPF). Since the synchronous rectification means, the smoothing means, the position error amplifier, the low pass filter (LPF) and the drive amplifier are provided and the rotational position of the rotor magnet can be detected with high sensitivity, the position of the rotor magnet can be stably and accurately controlled. .

FIG. 3 is a block diagram of the essential parts of a light quantity control device according to the present invention. In FIG. 3, the light quantity control device 4
0 is a motor unit 41, a sine wave oscillating means 47 and a resistance element 48.
And high-pass filter (HPF) 49 and synchronous rectification means 50
And a smoothing means 51, a position error amplifier 52, a low pass filter (LPF) 53, a drive amplifier 54, a resistance element 55 and an inductance coil 56. In addition, the motor unit 4
1 includes a drive coil 42, a rotor magnet 43, a conductive foil 44, a detection coil 45, and a spring 46.

The motor section 41 is a non-magnetic conductive coil 44 such as a drive coil 42 for controlling the rotor magnet 43, the rotor magnet 43, and the outer peripheral curved surface of the rotor magnet 43, such as aluminum foil or copper foil. The diaphragm blade, which is a light amount control member, is opened and closed by including a detection coil 45 that detects the rotational speed and position of the rotor magnet 43 and a spring 46 that acts in the direction of closing the diaphragm blade.

One end of the drive coil 42 is grounded, and the other end is connected to the output of the drive amplifier 54. The sine wave oscillating means 47 has a frequency sufficiently higher than the rotational operation response of the rotor magnet 43, and has a predetermined amplitude value and frequency.
Outputs 21.

The resistance element 48 and one end of the detection coil 45 are connected in series, and the resistance element 55 and the inductance coil 56 are connected.
Of the detection coil 45 and the other end of the inductance coil 56 are grounded to form a bridge circuit. The sine wave oscillating means 47 outputs a sine wave signal S21 to the connection point between the resistance element 48 and the resistance element 55 which are the input terminals of the bridge circuit.

The detection coil 45 is used as the output of the bridge circuit.
Is a detection coil signal in which the electromotive force (electromotive voltage) proportional to the relative speed between the rotor magnet 43 and the detection coil 45 is superimposed with the sine wave voltage applied to the detection coil 45 via the resistance element 48. S22 occurs. The phase of the detection coil signal S22 appearing in the detection coil 45 is the resistance element 4
8 and the detection coil 45, the resistance value of the resistance element 48 and the detection coil 45 with respect to the sine wave signal S21.
The phase advances by the phase determined by the inductance of.

Further, the inductance coil signal S appearing in the inductance coil 56 as the output of the bridge circuit.
The phase of 30 is the resistance element 55 and the inductance coil 56.
Since the sine wave signal S21 is made up of a series circuit, the phase advances by a phase determined by the resistance value of the resistance element 55 and the inductance of the inductance coil 56. ,

Similar to the operation principle of the detection coil 6 and the conductive foil 5 described in the embodiment of the light quantity control device 1 of FIG. 1, the conductive foil 44 is stretched around the outer peripheral curved surface of the rotor magnet 43. The relative distance between the detection coil 45 and the conductive foil 44 changes depending on the rotation angle of the rotor magnet 43, and the sine wave signal component amplitude of the detection coil signal S22 appearing on the detection coil 45 changes depending on the rotation angle of the rotor magnet 43. .

Detection coil signal S appearing on the detection coil 45
22 is input to a high-pass filter (HPF) 49, and the high-pass filter (HPF) 49 attenuates the low-frequency component of the detection coil signal S22 to obtain a HPF signal S23 which is synchronous rectification means 50.
Output to The synchronous rectification means 50 synchronously rectifies the HPF signal S23 with the inductance coil signal S30 appearing in the inductance coil 56 and outputs the rectified signal S24 to the smoothing means 51.

The smoothing means 51 smoothes the rectified signal S24 to generate a baseband signal having a potential proportional to the rotation angle of the rotor magnet 43, and the baseband signal is used as the position signal S25.
Is output to the inverting input terminal of the position error amplifier 52.
The position error amplifier 52 compares and amplifies the position signal S25 at the inverting input terminal and the target position signal S26 at the non-inverting input terminal and outputs the position error signal S27 to the inverting input terminal of the drive amplifier 54.

The detection coil signal S22 appearing in the detection coil 45 is input to the low pass filter (LPF) 53,
The low pass filter (LPF) 53 detects the detection coil signal S.
Attenuating 22 high frequency components, the rotor magnet 43
And an electromotive voltage component proportional to the relative speed of the detection coil 45 is output to the inverting input terminal of the drive amplifier 54 as a speed signal S28.

The drive amplifier 54 outputs a drive signal S29 to the drive coil 42 based on the position error signal S27 and the speed signal S28 input to the inverting input terminal to output the drive signal S29 to the rotor magnet 4.
3 is controlled. The position error signal S27 input to the inverting input terminal of the drive amplifier 54 is a feedback signal for controlling the rotor magnet 43 so that the error from the target position becomes zero, and is input to the inverting input terminal of the drive amplifier 54. The speed signal S28 is a feedback signal for stabilizing the control system by passing a current through the drive coil 42 to reduce the speed of the rotor magnet 43 to brake the rotor magnet 43.

As described above, the light quantity control device has a motor unit consisting of a drive coil, a rotor magnet, a conductive foil, a detection coil and a spring, a sine wave oscillating means, a resistance element, a high pass filter (HPF) and a synchronous rectification. Means, smoothing means, position error amplifier, low-pass filter (LPF), drive amplifier, resistance element, and inductance coil, and can detect the rotational position of the rotor magnet with high sensitivity, so that a stable and accurate rotor magnet Position control is possible.

Further, the synchronous rectification means 50 includes the detection coil 45.
Since only the sine wave signal component of the detection coil signal S22 appearing in (1) can be taken out, the position signal S25 with less noise can be obtained than the position signal S5 using the rectifying means 11.

[0052]

According to the light quantity control device of the present invention, the actuator is provided with a cylindrical rotor magnet having a non-magnetic conductive foil, and the rotor magnet is disposed in the vicinity of the rotor magnet to control the rotational position of the rotor magnet. It is equipped with a drive coil and a detection coil that is arranged close to the rotor magnet to detect the rotational position and rotational speed of the rotor magnet, and the actuator structure can be simplified and downsized. It is possible to provide a general light amount control device.

Further, the light quantity control device according to the present invention has a non-magnetic conductive foil on the outer peripheral curved surface of the rotor magnet,
Since the drive coil and the detection coil are arranged close to the outer peripheral curved surface of the rotor magnet and the structure of the actuator can be simplified and miniaturized, a compact and economical light quantity control device can be provided. .

Further, the light quantity control device according to the present invention is provided with a sine wave oscillating means for applying a sine wave signal to the detection coil, and the detection coil is provided with the eddy current loss generated in the conductive foil of the rotating rotor magnet. The rotation position of the rotor magnet is detected by the amplitude change of the applied sine wave signal,
Since the rotational position of the rotor magnet can be detected with high sensitivity, it is possible to provide a small-sized, high-performance, economical light quantity control device.

Further, the light quantity control device according to the present invention comprises sine wave oscillating means for applying a sine wave signal to the detection coil,
A position signal of the rotor magnet that detects the amplitude change of the sine wave signal applied to the detection coil due to the change of eddy current loss generated in the conductive foil of the rotating rotor magnet with high sensitivity,
(EN) Provided is an economical light quantity control device which is small in size, has better performance, because the position of a rotor magnet can be stably and accurately controlled by a speed signal which is an electromotive force generated in a detection coil by the rotation of a rotor magnet. You can

Therefore, the structure of the actuator is simple, the rotation position and the rotation speed of the rotor magnet can be detected with high sensitivity, noise is small, and the position of the rotor magnet can be stably and accurately controlled. An economical light quantity control device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of a light amount control device according to the present invention.

FIG. 2 is a block diagram of a main part of a light amount control device according to the present invention.

FIG. 3 is a block diagram of a main part of a light quantity control device according to the present invention.

FIG. 4 is a block diagram of a main part of a conventional light amount control device.

[Explanation of symbols]

 1, 20, 40, 60 ... Light quantity control device 2, 21, 41, 61 ... Motor part 3, 22, 42, 62 ... Drive coil 4, 23, 43, 63 ... Rotor magnet 5 , 24, 44 ... Conductive foil 6, 25, 45 ... Detection coil 7, 26, 46, 66 ... Spring 8, 47 ... Sine wave oscillating means 9, 28, 48, 55 ... -Resistance element 10, 29, 49 ... High-pass filter (HPF) 11 ... Rectification means 12, 31, 51 ... Smoothing means 13, 32, 52, 68 ... Position error amplifier 14, 33 , 53 ... Low-pass filter (LPF) 15, 34, 54, 69 ... Driving amplifier 27 ... Two-phase sine wave oscillating means 30, 50 ... Synchronous rectifying means 56 ... Inductance coil 65 ... Velocity detection coil 67 ... Position detection coil Pump S1, S11, S20, S21 ... Sine wave signal S2, S12, S22 ... Detection coil signal S3, S13, S23 ... HPF signal S4, S14, S24 ... Rectification signal S5, S15, S25 ... Position signal S6, S16, S26, S35 ... Target position signal S7, S17, S27, S36 ... Position error signal S8, S18, S28, S31 ... Speed signal S9, S19, S29, S37 ... Drive signals S32, S33 ... Hall electromotive force

Claims (4)

[Claims] 1. A light quantity control device comprising an actuator for opening and closing a diaphragm blade, which is a light quantity control member, wherein a cylindrical rotor magnet having a non-magnetic conductive foil is provided in the actuator, and the actuator is provided in proximity to the rotor magnet. A drive coil arranged to control the rotational position of the rotor magnet; and a detection coil arranged close to the rotor magnet to detect the rotational position and rotational speed of the rotor magnet. Light intensity control device. 2. The rotor magnet has a non-magnetic conductive foil on an outer peripheral curved surface thereof, the drive coil is disposed in the vicinity of the outer peripheral curved surface of the rotor magnet, and the detection coil is provided on the drive coil. 2. The light quantity control device according to claim 1, wherein the light quantity control device is arranged close to the outer peripheral curved surface of the rotor magnet which is 180 degrees opposite. 3. A sine wave oscillating means for applying a sine wave signal to the detection coil, wherein the sine wave signal applied to the detection coil is accompanied by a change in eddy current loss generated in a conductive foil of the rotating rotor magnet. The light amount control device according to claim 1 or 2, wherein the rotational position of the rotor magnet is detected by an amplitude change. 4. A sine wave signal applied to the detection coil, which is provided with the sine wave oscillating means for applying a sine wave signal to the detection coil, and which is applied to the detection coil in accordance with a change in eddy current loss generated in a conductive foil of the rotating rotor magnet. The rotor magnet is controlled to a predetermined position by a position signal of the rotor magnet that detects a change in the amplitude and a speed signal that is an electromotive force generated in the detection coil by the rotation of the rotor magnet. The light quantity control device according to claim 1 or 2.