JP2001154234A5 - - Google Patents

Description

[Claims]
[Claim 1]
Each coil has two sets of electromagnets in which a coil is wound around a stator arranged so as to have a phase difference of 90 degrees in electrical angle with respect to a cylindrical rotor magnet magnetized with multiple poles on the outer peripheral surface. and PM-type stepping motor of two-phase for forward and reverse rotation of said rotor magnet by energizing the alternating current,
The mechanical angle of the rotor magnet to the initial position of the rotor magnet based, the magnetized poles number of the rotor magnet as a P, a stopper for limiting the mechanical angle <(2 × 360 °) / P in the range of,
It is driven by the stepping motor and has two states, an open state and a closed state , at a restricted position by the stopper, and the light amount adjusting state is set between the open state and the closed state depending on the energization condition of the two sets of electromagnets. Variable light intensity adjustment member and
When setting the light amount adjustment value of the light amount adjusting member, the stepping motor is driven by the first drive pulse rate , and when the shutter operation using the light amount adjusting member is performed, the stepping motor is larger than the first drive pulse rate. Second drive of pulse rate A light amount adjusting device comprising a driving means for driving the stepping motor at a pulse rate.
2.
It said drive means, the light amount adjusting device according to claim 1, characterized in that the variable corresponding to the second driving pulse rate to the light amount adjustment value.
3.
An imaging device comprising the light amount adjusting device according to claim 1 or 2.

0007
[Means for solving problems]
The first configuration of the light amount adjusting device that realizes the object of the invention according to the present application is arranged so as to have a phase difference of 90 degrees in electrical angle with respect to a cylindrical rotor magnet that is multi-pole magnetized on the outer peripheral surface. and had two sets of electromagnets wound coils in the stator, said a PM type stepping motor of two-phase for forward and reverse rotation of said rotor magnet by energizing the alternating current to the coils, the initial position of the rotor magnet The mechanical angle of the rotor magnet is limited to a range of mechanical angle <(2 × 360 °) / P, where P is the number of magnetic poles of the rotor magnet, and the stepping motor is driven by the above. The amount of light has two states, an open state and a closed state, at a position restricted by the stopper, and the light amount adjustment state (throttle state) is variable between the open state and the closed state depending on the energization conditions of the two sets of electromagnets. When the adjustment member and the light amount adjustment value of the light amount adjustment member are set, the stepping motor is driven at the first drive pulse rate , and when the shutter operation using the light amount adjustment member is performed, the first drive pulse is performed. It has a driving means for driving the stepping motor at a second driving pulse rate having a pulse rate larger than the rate.

The second configuration of the light amount adjusting device for realizing the object of the invention according to this application, the first configuration, said drive means, which variable corresponds to the second driving pulse rate to the light amount adjustment value Is.

The configuration of the imaging device that realizes the object of the invention according to the present application includes a light amount adjusting device having any of the above configurations.

That is, a two-phase stepping motor in which the rotor magnet 1 rotates in synchronization with the generated rotating magnetic field by passing an alternating current having a phase difference of 90 ° to the A exciting coil 5 and the B exciting coil 7 is configured. ..

8 and 9 are first stoppers and second stoppers that come into contact with the swivel lever 3 to regulate the rotation of the swivel lever 3, and the rotor magnet 1 is based on the initial state when the A exciting coil 5 is energized in the ← direction. The mechanical angle of is ((2 × 360 °) / P) or less, that is, in the present embodiment, P = 4, so the mechanical angle is limited to the range of <180 °.

That is, when the mechanical angle of the rotor magnet 1 regulated by the first and second stoppers 8 and 9 becomes ((2 × 360 °) / P) or more, even if the A exciting coil 5 is energized in the → direction, the first Since the rotational force in the direction of returning from the state of being in contact with the first, second stoppers 8 and 9 to the initial state is not generated and the rotational force is generated in the opposite direction, the mechanical angle of the rotor magnet 1 is set to ((2 × 360 °). ) / P) It is necessary to make it less than or equal to.

That is, since the stop position of the lever can be determined according to the ratio of the energization amounts of the A exciting coil 5 and the B exciting coil 7, it is possible to set an arbitrary aperture value.

In FIG. 5, 10 is a two-phase stepping motor. Reference numeral 11 denotes a rotary lever fixed to the rotary shaft 2 of the stepping motor 10. The rotation position of the stepping motor 10 is restricted by contact between the two stoppers 12a and 12b provided on the stepping motor 10 and the lever 11. Will be done.

Here, in the small drawing state, the stepping motor determines the state of the initial position of the A exciting coil 5 according to the energization condition of FIG. 3 (1).

ST102: In the shooting mode, the drive pulse rate of the stepping motor is set to A [PPS]. It is desirable to set A [PPS] to a low pulse rate in order to guarantee the stop position accuracy of the aperture. Here, the pulse rate indicates the number of pulses for moving the motor in one second (step), and PPS indicates the pulse (step) / second. For example, the pulse rate of 480 (PPS) is the number of pulses (steps) that rotate the motor by 480 pulses (steps) per second, and a stepping motor with 20 steps / rotation rotates 24 times.

ST107: The drive pulse rate of the stepping motor is set to B [PPS]. B [PPS] is set to a higher pulse rate than when the aperture is set, and the closing operation (shutter operation ) is performed at high speed.

ST109: An image is captured using an image sensor (CCD) in synchronization with SW2. During this time, the operations of ST110 and ST111 are performed.

ST 212 : An image is captured using an image sensor (CCD) in synchronization with SW2. During this time, the operations of ST211 and ST213 are performed.

ST 211: drives the aperture in the closed position.