JP2012078690A - Light intensity adjustment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light intensity adjustment device which can be driven and controlled so as to shorten the release operation time by using s stepping motor.SOLUTION: The light intensity adjustment device operates aperture blades 5 of which the movement is restricted by cam grooves 601a to 601f of a cam plate 6, via a rotary plate 4 rotationally driven by a motor 1 to adjust an aperture value. A rotation position of a rotor 101 of the motor 1 is detected by a hole sensor 102, and a rotation position of the rotary plate 4 is detected by a photo-interrupter 3. A driving control unit 7 uses detection results of the hole sensor 102 and the photo-interrupter 3 and a driving table stored in a storage unit 7, to variably control a power supply phase at the driving start for the motor 1 and the number of driving steps to a target position of the rotor 101, which is required for the aperture blades 5 to achieve a target aperture value, in accordance with the rotation position of the rotor 101 calculated from the detection result of the hole sensor 102.

Description

  The present invention relates to a light amount adjusting device used for an imaging device or the like.

  At the time of imaging by the imaging device, in order to adjust or change the exposure of the subject to be imaged and the depth of field as desired by the photographer, the amount of light taken into the imaging device is adjusted using a light amount adjustment device (aperture mechanism). ing. For example, in the case of a single-lens reflex camera, in order to improve the continuous shooting speed, it is desired that the driving speed of the light amount adjusting device is high or the driving time is short.

  From the viewpoint of improving the driving speed, the light amount adjusting device is generally driven by a large motor provided in the camera or directly by a motor built in the light amount adjusting device. A stepping motor or the like is generally used as a motor built in the light amount adjusting device. In view of this, a technique has been proposed in which a detection means for detecting the rotational position of the rotor is provided, and a stepping motor capable of high-speed driving by control using the detection signal of the detection means is used to enable further high-speed driving. (See Patent Document 1).

  Further, a lens diaphragm driving device has been proposed in which a lens diaphragm mechanism is driven by a motor and the motor is reversely rotated at the start of a camera release operation so that the lens diaphragm mechanism is always in an open position (see Patent Document 2). According to this technique, since the aperture mechanism is reliably driven to the open position and then driven to a position where a predetermined aperture value can be obtained, an accurate aperture value can be obtained.

JP-A-10-150798 JP 58-043333 A

  However, in the lens aperture driving device disclosed in Patent Document 2, a certain amount of time is required for the initial positioning operation for reversing the motor before starting the release operation. Therefore, the operation time of the entire release operation is long. turn into. In addition, it is difficult to shorten the cycle of the release operation, and it is not easy to improve the continuous shooting speed.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a light amount adjustment device that can be driven and controlled so that the release operation time is shortened.

  A light amount adjusting device according to the present invention includes a stepping motor having a rotor, output means for outputting a periodic signal based on the rotational position of the rotor, a driven member driven by the motor, and the driven member A diaphragm blade that opens and closes the aperture when the aperture is driven, a detection unit that detects that the aperture blade is in an open state that opens the aperture, a signal output from the output unit, and a detection result of the detection unit Drive control means for controlling the driving of the stepping motor based on the output means, the output means from the state in which the aperture blade opens the opening and the driven member abuts against the stopper; Until the open state is no longer detected, different signals are output depending on the rotational position of the rotor, and the drive control means is controlled by the detection means. When the open state is detected, the number of steps until the aperture blade reaches the target aperture state is calculated based on an output signal from the output means, and an energization phase at the start of driving is determined. To do.

  According to the light amount adjusting device of the present invention, the release operation time can be shortened.

It is a disassembled perspective view of the light quantity adjustment apparatus which concerns on 1st Embodiment of this invention. It is a disassembled perspective view of the motor with which the light quantity adjustment apparatus of FIG. 1 is provided. FIG. 2 is a block diagram illustrating a configuration of a drive control system centered on a motor in the light amount adjustment device of FIG. 1. It is a figure which shows typically the relationship between each detection result of a hall | hole sensor and a photo interrupter in the drive control system of the light quantity adjustment apparatus of FIG. An example (a) of a drive table stored in the storage unit 8 used when the drive control unit 7 controls the drive of the motor 1 in the drive control system of the light amount adjusting device, and a reference result of the drive table corresponding to the number of steps. Examples (b) and (c). It is a flowchart which shows the control flow of the light quantity adjustment apparatus of FIG. It is a flowchart which shows the control flow of the light quantity adjustment apparatus which concerns on 2nd Embodiment of this invention. FIG. 7A schematically shows the process of step S105 in the flowchart of FIG. 7, and shows the drive frequency and required time when initial positioning is performed from the positions (i) to (v) shown in FIG. It is a table (b).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<< First Embodiment >>
FIG. 1 is an exploded perspective view of a light amount adjusting apparatus according to the first embodiment of the present invention. FIG. 2 is an exploded perspective view of a stepping motor 1 (hereinafter referred to as motor 1) provided in the light amount adjusting device of FIG.

  As shown in FIG. 1, the light amount adjusting device includes a motor 1, a cover plate 2, a photo interrupter 3, a rotary plate 4, an aperture blade 5 and a cam plate 6. As shown in FIG. 1, a motor 1 that is a rotational drive means of the light amount adjusting device is held on a cover plate 2, and the motor 1 includes a motor cover 107, a rotor 101, a bearing, as shown in FIG. 106, a yoke 103, and a pinion 108.

  As shown in FIG. 2, the rotor 101 has a structure in which a magnet 1012 magnetized in the rotation direction is attached to the outer periphery of the core 1011 and a shaft 1013 is attached to the center of rotation. One end of the shaft 1013 of the rotor 101 is fitted into the bearing 106 and the other end is fitted into a fitting hole 1071 provided in the motor cover 107. At the tip of the shaft 1013 on the output side (bearing 106 side), A pinion 108 is press-fitted with the yoke 103 interposed therebetween.

  The yoke 103 has pole teeth 103 a and 103 b facing the magnet 1012 in the radial direction of the magnet 1012. The pole teeth 103a and 103b are provided with bobbins 105a and 105b and exciting coils 104a and 104b wound around the bobbins 105a and 105b, respectively. The hall sensor 102 is fitted in a positioning hole 1072 provided in the motor cover 107 and faces the thrust surface of the magnet 1012. The Hall sensor 102 has two Hall elements A and B (not shown) inside the package, and detects two-phase magnetic fields with different thrust surfaces of the magnet 1012. The hall sensor 102 corresponds to an output unit that outputs a periodic signal based on the rotational position of the rotor 101.

  The rotary plate 4 shown in FIG. 1 is a driven member that is fitted in the inner hole of the cover plate 2 and is rotationally driven around the optical axis by the pinion 108 of the motor 1. The diaphragm blade 5 has a plurality (six in this embodiment) of light shielding blades 5a to 5f arranged in a circle around the optical axis. The dowels 501 a to 501 f provided on the light shielding blades 5 a to 5 f are fitted into holes 402 a to 402 f provided on the rotary plate 4, respectively, and are driven to rotate around the optical axis together with the rotary plate 4. The dowels 501a to 501f are also fitted in cam grooves 601a to 601f provided in the cam plate (cam member) 6, and the movement is restricted (guided) so as to move along the cam grooves 601a to 601f. Has been.

  In this way, the diaphragm blade 5 performs the opening / closing operation of the cylindrical optical path centering on the optical axis in conjunction with the change in the rotational position of the rotary plate 4 accompanying the rotational drive of the motor 1, thereby adjusting the light amount at the time of imaging. Done. In addition, the opening / closing operation by the diaphragm blades 5 on the columnar optical path centering on the optical axis is, in other words, the opening / closing operation by the diaphragm blades 5 of the opening of the cam plate 6.

  The photo interrupter 3 serving as detection means detects whether or not a detection unit (not shown) included in the photo interrupter 3 is shielded from light by the detected unit 401 provided on the rotary plate 4 that is rotated by the rotational drive of the motor 1. . The photo interrupter 3 detects that the aperture blade 5 is in an open state in which the opening is opened. As will be described later, when it is detected that the detection unit of the photo interrupter 3 is shielded from light (output signal is OFF), the aperture blade 5 that opens and closes the optical path as the rotary plate 4 rotates opens the optical path completely. Exists in the open position. That is, in the photo interrupter 3, the rotary plate 4 is in the rotational position corresponding to the state in which the aperture blade 5 is in the open position, or the aperture at which the aperture blade 5 achieves a predetermined aperture value (excluding the open value). It is detected whether it is in the rotational position corresponding to the state in position.

  FIG. 3 is a block diagram showing the configuration of the drive control system of the light amount adjusting device with the motor 1 as the center. The drive control unit 7 gives an excitation signal to the motor 1 with reference to the drive table stored in the storage unit 8 serving as storage means, and controls the drive of the motor 1. The rotation position of the rotor 101 during the drive control of the motor 1 is detected by the hall sensor 102. The drive control unit 7 can perform closed loop control using the detection result of the Hall sensor 102.

  The present embodiment is characterized in that the drive control unit 7 controls the drive of the motor 1 with reference to the drive table stored in the storage unit 8 according to the detection results of both the hall sensor 102 and the photo interrupter 3. Details thereof will be described below.

  FIG. 4 is a diagram schematically showing the relationship between the detection results of the hall sensor 102 and the photo interrupter 3 in the drive control system of the light quantity adjusting device. In FIG. 4A, the horizontal axis indicates the driving step of the motor 1 [the same applies to FIGS. 4B to 4E], and the final energization state of the motor 1 in each driving step is one phase. It is indicated by a stop position in energization (white circle) and a stop position in 2-phase energization (black circle).

  A position S shown in FIG. 4A corresponds to a stop position in the vicinity of the mechanical stopper of the rotary plate 4.

  FIG. 4B shows the output of the photo interrupter 3 and shows that ON / OFF is switched at the position P as a boundary. That is, in the region on the left side from the position P, the detection unit of the photo interrupter 3 is shielded from light, which indicates that the aperture blade 5 exists at the open position. On the other hand, in the region on the right side from the position P, the detection unit of the photo interrupter 3 is not shielded, which means that the diaphragm blade 5 is not in the open position, that is, the diaphragm blade 5 does not shield the optical path. It shows that it exists within the range of possible aperture positions.

  When the diaphragm blade 5 is moved to the open position, the rotary plate 4 generally collides with the mechanical stopper and repels due to inertial force. At this time, a wide area in which the output of the photo interrupter 3 is turned off is ensured so as not to move to a position where the output of the photo interrupter 3 is turned on again.

  FIG. 4C shows the magnetic flux that the magnet 1012 constituting the rotor 101 gives to the two Hall elements A and B of the Hall sensor 102. The magnetic fluxes detected by the Hall elements A and B are converted into the Hall element A output and the Hall element B output shown in FIGS. 4D and 4E by the ternary circuit in the Hall sensor 102.

  That is, the amount of rotation of the rotor 101 from the state where the rotary plate 4 contacts the mechanical stopper until the output of the photo interrupter 3 is turned OFF changes the signal output from the Hall sensor 102 by one period. Less than the amount of rotation. Therefore, different signals are output from the Hall sensor 102 depending on the rotational position of the rotor 101 from the state in which the rotary plate 4 is in contact with the mechanical stopper until the output of the photo interrupter 3 is turned OFF. Thus, if the output of the photo interrupter 3 is ON, the rotational position of the rotor 101 can be specified by the signal output from the hall sensor 102.

  FIG. 4F shows the final energized state of the motor 1 and the output of the Hall sensor 102 arranged in steps. FIG. 4 (f) shows that the combination of the final energization state of the motor 1 and the output of the Hall sensor 102 has a one-to-one correspondence with 9 steps as one cycle. When the output of the photo interrupter 3 is ON, that is, in the region on the right side from the position P, the rotational position of the rotor 101 is uniquely determined by the output of the Hall sensor 102.

  FIG. 5A is an example of a drive table stored in the storage unit 8 that is used when the drive control unit 7 controls the drive of the motor 1 in the drive control system of the light amount adjusting device. FIGS. 5B and 5C are examples of reference results of the drive table according to the number of steps. The number of steps in FIGS. 5B and 5C is the position shown in FIG. This represents the number of drive steps when S is the initial position. In the drive control of the motor 1, the number of drive steps according to the target aperture value set by the photographer and this drive table are used, and according to the number of drive steps as shown in FIGS. 5 (b) and 5 (c). Drive control.

  FIG. 6 is a flowchart showing a control flow of the light amount adjusting apparatus according to the present embodiment (first embodiment). At the start of the control flow, the camera system including the light amount adjusting device is in a state before entering the photographing operation. Also, this control flow ends when the operation of the light amount adjusting device is completed.

  First, the drive control unit 7 determines whether or not the output of the photo interrupter 3 is ON (step S1). When the output is not ON, that is, when the output is OFF (“NO” in S1), the rotary plate 4 does not exist at the rotation position where the aperture blade 5 is the open position. Since this is an error, the drive controller 7 drives (reversely rotates) the motor 1 in the direction of retracting the aperture blade 5 from the optical path (opening the aperture) (step S3), and then returns the processing to step S1. That is, it is determined again whether the aperture blade 5 has moved to the open position.

  When the output is ON (“YES” in S1), the photo interrupter 3 is shielded from light. That is, since the rotary plate 4 is in the rotational position where the diaphragm blade 5 is in the open position, the drive control unit 7 reads the output of the hall sensor 102 (step S2). The rotational position of the rotor 101 can be specified by the output of the hall sensor 102. In step S2, it is detected how many steps the current position of the rotor 101 is shifted with respect to the position S shown in FIG.

  After step S2, the drive control unit 7 calculates the required drive step number of the motor 1 from the number of steps from the position S to the current position of the rotor 101 and the aperture value set by the photographer, and at the start of driving. Is determined (step S4). Specifically, photographing from the current position of the rotor 101 is performed by subtracting the number of steps from the position S to the current position of the rotor 101 from the number of driving steps necessary to obtain the aperture value set by the photographer from the position S. The number of drive steps necessary to obtain the aperture value set by the person is obtained. The energization phase at the start of driving is determined by the output from the hall sensor 102. For example, when the rotor 101 is in the phase at the position P shown in FIG. 4, the output of the Hall sensor 102 is L / 0, and therefore the energization phase at the start of aperture drive in the next step (S5) is A− / Boff. To.

  In step S5, based on the calculation result in the previous step (S4), the drive control unit 7 controls the drive of the motor 1 by the method shown in FIG. That is, the drive control unit 7 determines the drive start energization phase and the number of drive steps to the target position of the rotor 101 for realizing the target aperture value set by the photographer by the aperture blade 5 before starting the drive. It changes based on the output of the hall sensor 102. In this way, aperture driving for narrowing the aperture blade 5 through the rotary plate 4 is performed, and the preparation for the exposure operation performed by the camera system is completed.

  As described above, according to the present embodiment, the motor can be used so that a desired aperture value can be obtained by the aperture blade 5 without performing the positioning operation of the initial position immediately before that is conventionally performed for aperture driving. 1 can be driven and controlled. As a result, the time required for adjusting the aperture value for each sequence in the continuous shooting of the camera system can be shortened, and high-speed shooting can be performed.

<< Second Embodiment >>
The light quantity adjustment device according to the second embodiment of the present invention differs from the light quantity adjustment device according to the first embodiment only in the control form of the motor 1 by the drive control unit 7. Specifically, in the light amount adjusting apparatus according to the present embodiment, the rotor 101 is initially positioned to a predetermined initial position immediately before the aperture driving by the aperture blade 5. In the present embodiment, this initial position is assumed to be the position S shown in FIG. 4 and is hereinafter referred to as “initial position S”.

  FIG. 7 is a flowchart showing a control flow of the light amount adjusting apparatus according to the present embodiment (second embodiment). At the start of the control flow, as in the first embodiment, the camera system including the light amount adjusting device is in a state before entering the photographing operation, and the control flow ends when the operation of the light amount adjusting device is completed. To do.

  The processing in steps S101 to S103 shown in FIG. 7 is the same as steps S1 to S3 described with reference to FIG. By step S102, it is detected how many steps the current position of the rotor 101 is shifted from the initial position S shown in FIG. Therefore, next, the drive control unit 7 calculates the number of steps for driving the rotor 101 to the initial position S performed in the next step (= step S105) (step S104).

  Subsequently, the drive control unit 7 drives and controls the motor 1 with a drive frequency corresponding to the number of steps up to the initial position S calculated in Step S104, and energizes the rotor 101 to move to the initial position S (Step S104). S105). Although details of step S105 will be described later, the position of the rotor 101 can be moved to the initial position S in an appropriate control time by this step S105. Thereafter, the drive control unit 7 performs the diaphragm drive similar to step S5 in FIG. 6 (step S106), and ends the control flow.

  FIG. 8A is a diagram schematically showing details of the process in step S105 of the flowchart of FIG. FIG. 8A shows the result of reading the output of the hall sensor 102 in step S102, and the motor control step and the ternary output of the hall elements A and B are shown in FIG. This is the same as the states shown in (a), (d), and (e). FIG. 8B shows the drive frequency and the time required for the initial positioning performed by the drive control unit 7 when the rotor 101 is in each of the positions (i) to (v) shown in (a). Yes.

  In any energization, the purpose is to obtain an initial position for returning the rotor 101 to the initial position S. Therefore, the drive control unit 7 energizes the A phase of the motor 1 with + energization. At this time, for example, in the case of (v) farthest from the initial position S, energization is performed at 400 PPS (400 pulses / second), and energization is performed for 2.5 msec to complete the initial position determination. As another example, it can be seen that when the movement distance for initial positioning is half (iii) as compared to the case of (v), the energization time may be half of 1.25 msec.

  According to the present embodiment, it is possible to reduce the time required for the initial positioning operation before driving the aperture to a minimum as necessary. As a result, the time required for each sequence in the continuous shooting of the camera system can be shortened, so that high-speed shooting can be performed.

<Other embodiments>
Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a camera system or a light amount adjusting device via a network or various storage media, and a computer (or CPU, MPU, or the like) of the camera system or light amount adjusting device. Is a process of reading and executing the program code. In this case, the program and the storage medium storing the program constitute the present invention.

DESCRIPTION OF SYMBOLS 1 Motor 3 Photo interrupter 4 Rotary plate 5 Diaphragm blade 6 Cam plate 7 Drive control part 8 Storage part 101 Rotor 102 Hall sensor 401 Detected part

Claims (4)

A stepping motor having a rotor;
Output means for outputting a periodic signal based on the rotational position of the rotor;
A driven member driven by the motor;
A diaphragm blade that opens and closes an opening by driving the driven member;
Detecting means for detecting that the aperture blade is in an open state for opening the opening;
Drive control means for driving and controlling the stepping motor based on a signal output from the output means and a detection result of the detection means;
The output means is configured to change the rotation position of the rotor between the state where the aperture blade opens the opening and the driven member contacts the stopper until the detection means does not detect the open state. Outputs different signals,
The drive control means calculates the number of steps until the diaphragm blades reach a target throttle state based on an output signal from the output means when the detection means detects the open state, and at the start of driving The light quantity adjusting device characterized by determining the energization phase. A stepping motor having a rotor;
Output means for outputting a periodic signal based on the rotational position of the rotor;
A driven member driven by the motor;
A diaphragm blade that opens and closes an opening by driving the driven member;
Detecting means for detecting that the aperture blade is in an open state for opening the opening;
Drive control means for driving and controlling the stepping motor based on a signal output from the output means and a detection result of the detection means;
The output means is configured to change the rotation position of the rotor between the state where the aperture blade opens the opening and the driven member contacts the stopper until the detection means does not detect the open state. Outputs different signals,
The drive control means drives the rotor from the current position to the initial position on the basis of an output signal from the output means when the open state is detected by the detection means, and then moves the aperture blade to a target aperture. A light quantity adjusting device, wherein the number of steps up to the state is supplied to the stepping motor.   3. The light quantity adjustment according to claim 2, wherein the drive control means sets the drive frequency and energization time of the stepping motor from the current position to the initial position based on an output signal from the output means. apparatus. The drive control means is configured such that the amount of rotation of the rotor from the state in which the aperture blade opens the opening and the driven member contacts the stopper until the detection means no longer detects the open state is the output means. 3. The light amount adjusting device according to claim 1, wherein the light amount adjusting device is set so as to be smaller than an amount of rotation of the rotor required for changing a signal output from one cycle.

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