JP2015200821A - Light amount adjustment device and optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light amount adjustment device that is low cost, capable of energy conservation drive, and having high reliability.SOLUTION: A light amount adjustment device includes: driving means; first detecting means capable of detecting the position of the driving means; a driving member to be driven by the driving means; second detecting means capable of detecting an area where the driving member is located; and position calculation means capable of calculating the position of the driving member based on the position of the driving means detected by the first detecting means and the area where the driving member detected by the second detecting means is located.

Description

  The present invention relates to a light amount adjusting device and an optical apparatus.

  Conventionally, a digital single-lens reflex camera capable of shooting a moving image has been proposed. During moving image shooting, the aperture diameter is controlled in accordance with the brightness of the subject even during recording, including during the display of an image on the liquid crystal display unit before the start of recording. When there is no change in the brightness of the subject during image display on the liquid crystal display unit or during moving image shooting, it is desirable to turn off the motor to save energy. However, if the power is turned off, it is impossible to guarantee the position (opening diameter) of the aperture blade. For example, when vibration is applied to the camera after the power is turned off, the aperture diameter of the diaphragm may change. If the absolute position detection means is provided, it is possible to guarantee the position of the diaphragm blades even when the motor is de-energized. Generally, the absolute position detection means is expensive such as an optical encoder or a linear scale. Sensor is required. For this reason, in the conventional light quantity adjusting device, normally, the motor is not turned off to ensure the position of the aperture blade.

  In Patent Document 1, the origin position of the movable part is detected by the origin position detection means, the relative position of the movable part is detected by the relative position detection means, and the absolute position of the movable part is calculated from the detection results of these two detection means. Thus, the absolute position of the apparatus is detected with a relatively low-cost configuration.

JP 2007-065251 A

  However, in Patent Document 1, since the absolute position is calculated from the origin position and the relative position therefrom, it is necessary to return the movable part to the origin position when the power is turned off. When such a mechanism is used for the light amount adjusting device, the light amount changes when the movable part is returned to the origin position, so that the motor cannot be de-energized during movie shooting, and as a result, energy saving cannot be achieved. .

  In view of such a problem, an object of the present invention is to provide a light amount adjusting device that is low in cost, capable of energy saving driving, and has high reliability.

  A light amount adjusting device according to one aspect of the present invention includes a driving unit, a first detecting unit capable of detecting a position of the driving unit, a driven member driven by the driving unit, and a position of the driven member. Based on the second detection means capable of detecting the area to be detected, the position of the driving means detected by the first detection means, and the area where the driven member is detected detected by the second detection means. And a position calculating means capable of calculating the position of the driven member.

  According to the present invention, it is possible to provide a light quantity adjusting device that is low in cost, capable of energy saving driving, and has high reliability.

It is a block diagram of the optical apparatus provided with the light quantity adjustment apparatus which concerns on embodiment of this invention. It is a disassembled perspective view of the light quantity adjustment apparatus of Example 1. FIG. It is an external appearance perspective view of a step motor. It is an axial sectional view of a step motor. It is a figure which shows the sensor signal process of the rotor position detection sensor of a step motor. It is a figure which shows the positional relationship of the light-shielding part of the rotation member of Example 1, and the light projection slit of an optical sensor. 6 is a flowchart illustrating an operation of an optical apparatus including the light amount adjusting device according to the first embodiment. It is a flowchart which shows the process of still image photography. It is a flowchart which shows the process of video recording. It is a flowchart which shows the process of light quantity adjustment. It is a figure which shows the positional relationship of the light-shielding part of the rotation member of Example 2, and the light projection slit of an optical sensor. 6 is a flowchart illustrating an operation of an optical apparatus including the light amount adjusting device according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted. Hereinafter, as an application example of the present invention, the light amount adjusting device will be described in the present embodiment, but the present invention may be applied to, for example, an AF driving device or a zoom driving device.

  FIG. 1 is a block diagram of an optical apparatus 500 including a light amount adjusting device 100 according to an embodiment of the present invention.

  Light from the subject enters the image sensor 23 through the photographing lens 22. A light amount adjusting device 100 described later is incorporated in the photographing lens 22 and is driven by a step motor (hereinafter referred to as a motor) 12.

  The image sensor 23 is composed of a photoelectric conversion element such as a CCD or CMOS sensor. The control circuit 24 includes a microcomputer that controls the entire optical apparatus 500. An output signal obtained by photoelectric conversion in the image sensor 23 is amplified by the control circuit 24 and output as a digital video signal. In the optical apparatus 500 according to the present embodiment, a moving image / still image is formed using a digital video signal. The monitor display circuit 32 displays the digital video signal on image display means (not shown) such as a liquid crystal display device.

  The motor drive circuit 25 drives the motor 12 based on the calculated aperture value. At that time, the coil energization is switched based on the inputted drive pulse interval (drive frequency).

  The absolute position detection circuit (position calculation means) 26 calculates the absolute position of the rotating member 9 described later from the outputs of the optical sensor 14 and the first rotor position detection sensor 171 and the second rotor position detection sensor 172 of the motor 12. To do.

  The photometric circuit 27 detects light from the subject using a photometric sensor (not shown), and outputs a detection signal to the control circuit 24. The control circuit 24 calculates an optimum shutter speed and aperture value based on this detection signal. The shutter drive circuit 30 drives the shutter device 31 based on the calculated shutter speed.

  The mirror drive circuit 28 places the mirror 29 in the photographing optical path in the observation state of the optical finder (not shown), and puts the mirror 29 outside the photographing optical path in the photographing state and the electronic finder observation state in which the real-time image is displayed on the image display means. Evacuate.

  The power switch 33 selects power activation of the optical device 500. The SW1 switch 34 is activated by half-pressing a release button (not shown). The SW2 switch 35 is activated by fully pressing the release button. The recording switch 36 can select the start and end of recording in the moving image shooting mode. The shooting mode changeover switch 37 can select a first shooting mode capable of shooting a still image and a second shooting mode capable of shooting a moving image by switching a mode dial switch or the like.

  First, the configuration of the light amount adjusting device 100 of this embodiment will be described with reference to FIG. FIG. 2 is an exploded perspective view of the light amount adjusting device 100 of this embodiment. The light quantity adjusting device 100 includes light shielding blades 1 to 8, a rotating member 9, a cam member 10, a pressing member 11, a motor 12, a first rotor position detection sensor 171, a second rotor position detection sensor 172, a pinion gear 13, and an optical sensor 14. And a holding member 15.

  The light shielding blades 1 to 8 are equally arranged in the circumferential direction around the optical axis, and control the aperture opening by overlapping the light shielding bases. The larger the overlap, the smaller the aperture opening amount. Columnar or cylindrical first shaft portions 1a to 8a are formed on the first surface of the base of the light shielding blades 1 to 8, and columnar or cylindrical second shaft portions (not shown) 1b to 8b are formed on the second surface. Is formed.

  The rotating member (driven member) 9 is a ring-shaped member having an opening 9a formed at the center. The rotating member 9 is formed with holes 9b to 9i, a rotation fitting projection 9j, a gear portion 9k, and a light shielding portion 9l. The cam member 10 is a ring-shaped member having an opening 10a formed at the center. Cam groove portions 10 b to 10 i are formed in the cam member 10. The pressing member 11 is a ring-shaped member having an opening 11a formed at the center. The holding member 11 is formed with a hole portion 11b, a motor attachment portion 11c, and a slit portion 11d.

  The pressing member 11 is fixed to the cam member 10 with the light shielding blades 1 to 8 and the rotating member 9 interposed therebetween, and prevents the light shielding blades 1 to 8 and the rotating member 9 from coming off in the optical axis direction. At that time, the rotation fitting protrusion 9j of the rotating member 9 is fitted to the opening 11a of the pressing member 11 and is rotatably supported. Further, the first shaft portions 1 a to 8 a of the light shielding blades 1 to 8 are rotatably fitted in the holes 9 b to 9 i of the rotating member 9, respectively, and the second shaft portions 1 b to 8 b are cams of the cam member 10. Each of the grooves 10b to 10i is slidably fitted.

  The motor 12 drives the rotating member 9. The pinion gear 13 fixed to the shaft tip of the motor 12 is attached to the motor attachment portion 11 c of the presser member 11. The pinion gear 13 passes through the hole portion 11 b of the pressing member 11 and meshes with the gear portion 9 k of the rotating member 9.

  The optical sensor 14 has a light receiving part and a light emitting part. The optical sensor 14 is fixed to the presser member 11 by a holding member 15. Between the light emitting part and the light receiving part, a light shielding part 9l of the rotating member 9 is arranged. The light-shielding part 9l has a plurality of continuous light-shielding walls (light-shielding areas) having different shapes, and detects the light-shielding condition of light reaching the light-receiving part from the light-emitting part, whereby the position of the rotating member 9 is changed to a plurality of areas Separately detect optically.

  Next, the configuration of the motor 12 will be described with reference to FIGS. 3 and 4. 3 is an external perspective view of the motor 12, and FIG. 4 is an axial sectional view of the motor 12.

  The motor 12 includes a magnet 161, a shaft 162, a core 167, a first coil 163, a second coil 164, a first yoke 165, a second yoke 166, a first rotor position detection sensor 171 and a second rotor position detection sensor 172. . The magnet 161, the shaft 162, and the core 167 constitute a rotor. The first and second coils 163 and 164, the first and second yokes 165 and 166, and the first and second rotor position detection sensors 171 and 172 constitute a stator. The rotor is rotatably supported with respect to the stator.

  As shown in FIG. 3, the magnet 161 is a cylindrical permanent magnet whose outer periphery is multipolarly magnetized. By magnetizing the outer periphery of the cylindrical shape, the inner periphery is magnetized to a pole opposite to the outer periphery. The magnet 161 has a magnetization pattern in which the strength of the magnetic force in the radial direction changes in a sine wave shape with respect to the angular position. In addition, although the magnet 161 of a present Example is magnetized by 10 poles, it is not limited to 10 poles.

  The first yoke 165 has five magnetic pole teeth excited by the first coil 163, and the magnetic pole teeth are opposed to the outer peripheral surface of the magnet 161 with a predetermined gap. The second yoke 166 has five magnetic pole teeth excited by the second coil 164, and the magnetic pole teeth are opposed to the outer peripheral surface of the magnet 161 with a predetermined gap. The first yoke 165 is disposed at a position shifted by 90 ° in electrical angle with respect to the second yoke 166.

  The first and second rotor position detection sensors 171 and 172 are magnetic sensors that can magnetically detect the rotational position of the rotor. As shown in FIG. 3, the first and second rotor position detection sensors 171 and 172 are opposed to each other so as to have a predetermined gap from the outer peripheral surface of the magnet 161 in a state where they are deviated from each other by 90 ° in electrical angle. . Here, if the number of poles of the magnet 161 is n, the electrical angle of 360 ° corresponds to the actual rotor angle of 720 ° / n.

  FIG. 5 is a diagram illustrating sensor signal processing of the first and second rotor position detection sensors 171 and 172 of the motor 12. In FIG. 5, the horizontal axis is the energization phase during the 1-2 phase drive of the motor 12, and the first coil 163 is represented as A phase and the second coil 164 is represented as B phase. In this embodiment, as shown in the figure, eight kinds of energization phases are repeated from the left, A + / B +, A + / B0, A + / B−,. The rotor rotates corresponding to the energization phase.

  The upper graph in FIG. 5 is an analog output of the first and second rotor position detection sensors 171 and 172 which are magnetic sensors. The vertical axis represents the signal output with the S pole on the top and the N pole on the bottom centered on 0. In the figure, a sensor signal α indicated by a solid line is an output of the first rotor position detection sensor 171, and a sensor signal β indicated by a broken line is an output of the second rotor position detection sensor 172. Since the strength of the magnetic force in the radial direction of the magnet 161 is magnetized so as to be approximately sinusoidal with respect to the electrical angle, the sensor signals α and β are shifted from each other by 90 ° in electrical angle as shown in the figure. It becomes a substantially sinusoidal signal. In the present embodiment, one cycle (360 °) is obtained with eight energization phases during 1-2 phase driving.

  The ternary signals α ′ and β ′ are 0 when the sensor signals α and β are less than a predetermined value, High (H) when the S pole signal output is equal to or higher than the predetermined value, and the N pole signal output is equal to or higher than the predetermined value. In this case, the signal is converted into a low (L) ternary value. As shown in the figure, the output after ternarization is divided into 8 types, and 8 types of output are repeated in one cycle. Since it coincides with the number of energized phases during the 1-2 phase driving of the motor 12, the stop position of the motor 12 in 8 steps can be detected. That is, the stop position of the motor 12 can be represented by 8 positions by the ternary signals α ′ and β ′ (for example, “position 1” if “α: H, β: L” in the ternary display, The motor energization phase at that time is “A phase: +, B phase: +”).

  In this embodiment, the number of magnetic poles of the magnet 161 is 10, and when driven by 1-2 phase driving, the number of steps required for one rotation of the motor 12 is 40 steps. Since the detected number of rotation positions of the rotor in one cycle of the motor 12 is 8, the same position appears five times during one rotation. Therefore, for example, even if the output after ternarization of position 1 (α: H, β: L) is obtained, it cannot be detected where it is located among the five locations in one rotation.

  FIG. 6 is a diagram showing the positional relationship between the light shielding portion 9l of the rotating member 9 and the light emitting slit of the light emitting portion of the optical sensor 14 according to the present embodiment. The light shielding part 9l has a plurality of light shielding walls having different heights. The leftmost wall is an initial position area where the projection slit is completely covered. The second wall from the left is a first region where the light projection slit is completely exposed (the light blocking ratio is 0%). The third wall from the left is a second region in which the light blocking ratio of the projection slit is 20%. The fourth wall from the left is a third region where the light blocking ratio of the light projecting slit is 40%. The fifth wall from the left is a fourth region in which the light blocking ratio of the projection slit is 60%. The rightmost wall is a fifth region where the light blocking ratio of the light projecting slit is 80%.

  The number of running steps of the motor 12 is set to 2 steps, and the light projection slit is set to be in the initial position region from the initial position to the running period. From the third step, the light shielding blades 1 to 8 begin to enter the opening 10a of the cam member 10, and the light projecting slit enters the first region (actually, the light shielding portion 9l (rotating member 9) is the motor 12). Rotating and moving in conjunction with the light projection slit does not move).

  The stop positions (detection positions) of the motor 12 in each area from the first to the fifth areas are set to 8 positions, and the stop positions in each area are the first and second rotor position detection sensors 171. , 172 corresponding to eight kinds of ternary positions obtained from the sensor signals. That is, the number of detections of the rotational position of the rotor by the first and second rotor position detection sensors 171 and 172 is the same as the number of stop positions in each region.

  In FIG. 6A, the light projecting slit is located in the initial position region and position 6 of the light shielding portion 9l. In the initial state when the optical apparatus equipped with the light amount adjusting device of this embodiment is turned off or turned on, the motor 12 is controlled so that the light blocking portion 9l of the rotating member 9 completely covers the projection slit. The The ternary display at the rotor stop position of the motor 12 is “α: 0, β: H” at position 6, and the motor energization phase is “A phase: −, B phase: 0”. At this time, the light shielding blades 1 to 8 of the light amount adjusting device 100 are in an open state in which they are retracted outside the opening 10 a of the cam member 10. When the power is turned on, the output value of the light receiving portion of the optical sensor 14 is detected to determine whether or not the rotating member 9 is located at the initial position, that is, whether or not the light projecting slit is located in the initial position region of the light shielding portion 9l. . When the light projection slit is located in the initial position region, it is determined whether or not the ternary display as the sensor signal values of the first and second rotor position detection sensors 171 and 172 is “α: 0, β: H”. judge.

  In FIG. 6B, the light projecting slit is located in the first region and position 1 of the light shielding part 9l. This state is a state in which the motor 12 is rotated three steps from the initial position state of FIG. 6A, and the light projection slit is completely exposed from the light shielding portion 9l. The ternary display at the rotor stop position of the motor 12 is “α: H, β: L” which is position 1, and the motor energization phase is “A phase: +, B phase: +”.

  In FIG. 6C, the light projecting slit is located in the second region and position 2 of the light shielding portion 9l. This state is a state in which the motor 12 is rotated 12 steps from the initial position state of FIG. 6A and the light blocking ratio of the light projecting slit of the light blocking portion 91 is 20%. The ternary display at the rotor stop position of the motor 12 is “α: 0, β: L” which is position 2, and the motor energization phase is “A phase: +, B phase: 0”.

  In FIG. 6D, the light projecting slit is located in the third region and the position 5 of the light shielding portion 9l. This state is a state in which the motor 12 is rotated 23 steps from the initial position state of FIG. 6A and the light blocking ratio of the light projecting slit of the light blocking portion 91 is 40%. The ternary display at the stop position of the rotor of the motor 12 is “α: L, β: H” at position 5, and the motor energization phase is “A phase: −, B phase: −”.

  In FIG. 6E, the light projecting slit is located in the fourth region and position 6 of the light shielding portion 9l. This state is a position obtained by rotating the motor 12 by 32 steps from the initial position state of FIG. 6A, and is a state where the light blocking ratio of the light projecting slit of the light blocking portion 91 is 60%. The ternary display at the rotor stop position of the motor 12 is “α: 0, β: H” at position 6, and the motor energization phase is “A phase: −, B phase: 0”.

  In FIG. 6 (f), the light projection slit is located in the fifth region and the position 8 of the light shielding part 9 l. This state is a position obtained by rotating the motor 12 by 42 steps from the initial position state of FIG. 6A, and is a state where the light blocking ratio of the light projecting slit of the light blocking portion 91 is 80%. The ternary display at the rotor stop position of the motor 12 is “α: H, β: 0” at position 8, and the motor energization phase is “A phase: 0, B phase: +”.

  As described above, the region of the light shielding portion 9l is determined from the output of the optical sensor 14, and the position in the region is calculated from the outputs of the first and second rotor position detection sensors 171 and 172, thereby The absolute position can be calculated.

  In this embodiment, the number of detections of the rotational position of the rotor in one cycle of the motor 12 of the first and second rotor position detection sensors 171 and 172 is 8, and the motor 12 is stopped in one area of the light shielding portion 9l. The number of positions is also eight. However, the number of detected rotational positions of the rotor of one cycle of the motor 12 of the first and second rotor position detection sensors 171 and 172 is set to be equal to or greater than the number of stop positions of the motor 12 in one region of the light shielding portion 9l. If so, the absolute position of the rotating member 9 can be calculated.

  The operation of the optical apparatus provided with the light amount adjusting device of this embodiment will be described with reference to the flowcharts of FIGS.

  In FIG. 7, the operation of the optical apparatus 500 is started in step (hereinafter, step notation is omitted) S1, and the power switch 33 is in a standby state in S2. When the power switch 33 is turned on, the process proceeds to S3.

  In S3, the shooting mode selected by the shooting mode switch 37 is determined. When the shooting mode changeover switch 37 selects the first shooting mode capable of shooting a still image, the process proceeds to S4, where still image shooting is performed and the second shooting mode capable of shooting a movie is selected. Advances to S5 to shoot a moving image. Details of still image shooting and moving image shooting will be described later with reference to FIGS. After the operation of S4 or S5 is completed, the process proceeds to S6 and the operation of the optical device 500 is completed.

  The still image shooting process in S4 of FIG. 7 will be described with reference to the flowchart of FIG. In S11, the still image shooting process is started. In S12, the state of the SW1 switch 34 is determined. When the SW1 switch 34 is on, the process proceeds to S14, and when it is off, the process proceeds to S13.

  In S13, processing according to operations other than the SW1 switch 34 is performed. For example, it is possible to change the shooting setting, but since it is not a main part of the present invention, the description is omitted.

  In S14, the subject is measured by the photometry circuit 27. In S15, the shutter speed and the aperture value are calculated based on the photometric values in S14.

  In S16, the SW2 switch 35 is in a standby state. If the SW2 switch 35 is on, the process proceeds to S17. In S <b> 17, the optical sensor 14 detects the area of the light shielding portion 9 l of the rotating member 9. In S18, if necessary according to the detection result in S17, initial positioning is performed. Specifically, if the light projection slit of the optical sensor 14 is not located in the initial position area of the light shielding unit 9l, the motor 12 is referred to as the stop direction until the optical sensor 14 detects the initial position area of the light shielding unit 91. A motor return drive that rotates in the reverse direction is performed. Thereafter, based on the calculation result of the aperture value in S15, the motor 12 is driven to reach a predetermined aperture position.

  Here, drive control of the light amount adjusting device 100 will be described. First, after the motor 12 is initially energized at a predetermined energization phase, the driving of the motor 12 is started by 1-2 phase driving. When the motor 12 is rotated counterclockwise in FIG. 1, the pinion gear 13 is rotated. Since the pinion gear 13 meshes with the gear portion 9k of the rotating member 9, the rotating member 9 rotates in the clockwise direction of FIG. When the first shaft portions 1 a to 8 a of the light shielding blades 1 to 8 fitted in the holes 9 b to 9 i of the rotating member 9 are rotated, the second shaft portions (not shown) 1 b to 8 b of the cam member 10 are rotated. It moves along the cam groove portions 10b to 10i. When the light shielding blades 1 to 8 perform the same rotation operation, the opening 10a of the cam member 10 is narrowed down. Then, it stops at the target position (target step number). Needless to say, it is not necessary to drive the light amount adjusting device 100 when the calculated aperture value is in the open state. The same applies to the case where the user sets the aperture to the full aperture in the shooting mode in which the user sets an arbitrary aperture value.

  In S19, a series of shooting operations are performed. First, the mirror 29 is retracted out of the photographing optical path by the mirror driving circuit 28, the shutter device 31 is driven by the shutter driving circuit 30 to open the shutter, and capturing (exposure) of photographing image data from the image sensor 23 is started. When the predetermined exposure time is finished, the shutter drive circuit 30 drives the shutter device 31 to close the shutter, and the exposure of the image sensor 23 is finished, thereby ending the exposure. Finally, the mirror 29 retracted from the photographing optical path by the mirror driving circuit 28 is returned to the original position.

  In S20, the light quantity adjusting device 100 is controlled to drive the diaphragm to the standby position state (open state). At this time, the control of the light quantity adjusting device 100 is performed by 1-2 phase driving similarly to the narrowing driving, and the diaphragm is rotated to the standby position by rotating the motor 12 in the clockwise direction of FIG. 1 contrary to the narrowing driving. Drive to the state (open state). Since the drive control of the light amount adjusting device 100 is the same as that in the narrowing drive, detailed description is omitted. In S21, the still image shooting process is terminated.

  The moving image shooting process in S5 of FIG. 7 will be described using the flowchart of FIG. In S 31, the moving image shooting process is started. In S 32, the mirror 29 is retracted out of the photographing optical path by the mirror driving circuit 28, the shutter device 31 is driven by the shutter driving circuit 30 to open the shutter, and the subject image is picked up from the image sensor 23. Start reading data sequentially. In S33, the light amount adjustment is started by controlling the light amount adjusting apparatus 100. Details of the light amount adjustment will be described later with reference to FIG. In S34, the captured subject image data is set to a through display state in which the monitor display circuit 32 sequentially displays the image on the image display means (not shown).

  In S35, the state of the recording switch 36 is determined. When the recording switch 36 is on, the process proceeds to S36, and when it is off, the process proceeds to S39. In S36, exposure of the image sensor 23 is started, and the control circuit 24 reads out a charge signal (photographed image data) from the image sensor 23 for each frame of the moving image, and performs predetermined processing such as digital conversion, image processing, and image compression. After recording, recording to be written in a memory (not shown) is started. In S37, the state of the recording switch 36 is determined again. If the recording switch 36 is on, the recording in S36 is continued, and if it is off, the process proceeds to S38. In S38, the recording ends.

  In S39, the state of the power switch 33 is determined. If the power switch 33 is on, the process returns to step S35 to enter the standby state of the recording switch 36. If it is off, the process proceeds to S40. In S40, the light amount adjustment by the light amount adjustment apparatus 100 is finished. In S41, the through display state of sequentially displaying on the image display means (not shown) by the monitor display circuit 32 is ended. In S42, the mirror 29 that has been retracted out of the photographing optical path by the mirror drive circuit 28 is returned to the original position, and the shutter device 31 is driven by the shutter drive circuit 30 to close the shutter. In S43, the moving image shooting process ends.

  The light quantity adjustment process in S33 of FIG. 9 will be described using the flowchart of FIG. In S51, light amount adjustment processing is started, and in S52, subject photometry is performed using subject image data captured by the image sensor 23 (different from the photometry method at the time of still image shooting).

  In S53, the photometric value in S52 is compared with the previous value to determine whether there is a change in brightness. If there is a change in brightness, the process proceeds to S54, and if there is no change in brightness, the process returns to S52 to perform photometry again. Here, since moving image shooting is started and there is no previous value in the first photometry, the process directly proceeds to S54.

  In S54, an appropriate aperture value is calculated based on the photometric value in S52. Here, AE control is performed by combining the control of the light amount adjusting device 100 (control of the aperture value), the electronic shutter of the image sensor 23, and the ISO sensitivity until it can be determined that the exposure (AE) is appropriate. In S55, the optical sensor 14 detects the area of the light shielding portion 9l of the rotating member 9. In S56, the outputs of the first and second rotor position detection sensors 171 and 172 are ternarized to calculate a ternary position of the rotor 12 stop position. In S57, the absolute position detection circuit 26 calculates the absolute position of the rotating member 9 based on the region of the light shielding part 9l detected in S55 and the ternary position of the rotor stop position calculated in S56. In S58, the required drive amount of the motor 12 is calculated from the ideal position of the rotating member 9 corresponding to the appropriate aperture value calculated in S54 and the current position (absolute position) of the rotating member 9 calculated in S57. After the power is turned on, predetermined driving is performed. After the driving of the motor 12 is completed, the power of the motor 12 is turned off. In S59, the light amount adjustment process is terminated. The light amount adjustment process is repeatedly performed at predetermined time intervals by a predetermined timer.

  As described above, in the light amount adjusting device of this embodiment, the region of the light shielding unit 9l is determined from the output of the optical sensor 14, and the position in the region is determined from the outputs of the first and second rotor position detection sensors 171 and 172. By calculating, the absolute position of the rotating member 9 can be calculated. This is significantly less expensive than general absolute position detection sensors such as optical encoders and linear scales.

  In addition, since the optical apparatus including the light amount adjusting device of this embodiment can calculate the absolute position of the rotating member 9, it is necessary to return the motor 12 to the initial position when the motor 12 is turned off and then turned on again. There is no. Therefore, it is possible to turn off the motor 12 when there is no change in the amount of light during moving image shooting, and even in that case, the reliability of light amount adjustment can be ensured.

  Therefore, the present invention can provide a light amount adjusting device that is low in cost, capable of energy saving driving, and has high reliability.

  The light amount adjusting device 200 of the present embodiment has a rotating member 19 corresponding to the rotating member 9 of the light amount adjusting device 100 of the first embodiment. Other configurations are the same as those of the light amount adjusting apparatus 100 of the first embodiment. In the rotating member 19, the shape of the light shielding portion 19 l is different from the shape of the light shielding portion 9 l of the rotating member 9. Other configurations are the same as the configuration of the rotating member 9. FIG. 11 is a diagram illustrating a positional relationship between the light shielding portion 19l of the rotating member 9 and the light projecting slit of the optical sensor 14 according to the present embodiment. In the figure, the broken line indicates the position of the light projection slit of the optical sensor 14 before the movement of the motor 12, and the solid line indicates the position of the light projection slit after the motor 12 has moved one step. 11 (a) to 11 (f) show a case where one step is moved in the narrowing direction, while FIGS. 11 (g) and 11 (h) show a case where the step is moved one step in the opening direction. As shown in FIG. 11, each area range differs depending on the moving direction ((g) and (h) are shifted to the left by one step with respect to (a) to (f)).

  As shown in FIG. 11, the light shielding part 191 has a plurality of light shielding walls having different heights or angles. The leftmost wall is an initial position area (partial running area) that is flat and the projection slit is completely covered. The second wall from the left is a first region that is flat and the projection slit is completely exposed. The third wall from the left is a second region that is a slope that rises to the right. The fourth wall from the left is a third region that is flat and has a light blocking ratio of about 70%. The fifth wall from the left is a fourth region that is a slope that slopes downward to the right. The sixth wall from the left is a fifth region that is flat and has a light blocking ratio of about 30%. In the light shielding unit 19l of this embodiment, a region where the light shielding state does not change and a region where the light shielding state changes are adjacent to each other. The range of the arrow indicating each region is shifted from the boundary of each wall in consideration of the position of the projection slit after one step movement.

  The number of running steps of the motor 12 is set to 4 steps, and the light projection slit is set to be in the initial position region from the initial position to the running period. From the fifth step, the light shielding blades 1 to 8 begin to enter the opening 10a of the cam member 10, and the light projecting slit enters the first region (actually, the light shielding portion 19l (rotating member 19) is the motor 12). Rotating and moving in conjunction with the light projection slit does not move).

  The stop positions of the motor 12 in each of the first to fourth areas are set to 8 positions, and the stop positions of the motor 12 in the fifth area are set to 6 positions. Stop positions in each region correspond to eight types of ternary positions obtained from the sensor signals of the first and second rotor position detection sensors 171 and 172. That is, the number of rotor rotation position detection phase divisions by the first rotor position detection sensor 171 and the second rotor position detection sensor 172 is set to be greater than the number of step stop position divisions in each region.

  In FIG. 11A, the light projecting slit is located in the initial position region and position 4 of the light shielding portion 191. In the initial state when the optical apparatus equipped with the light amount adjusting device of this embodiment is turned off or turned on, the motor 12 is controlled so that the light shielding portion 19l of the rotating member 19 completely covers the projection slit. The The ternary display at the stop position of the rotor of the motor 12 is “α: L, β: 0” at position 4, and the motor energization phase is “A phase: 0, B phase: −”. At this time, the light shielding blades 1 to 8 of the light amount adjusting device 200 are in an open state in which they are retracted outside the opening 10 a of the cam member 10. When the power is turned on, the output value of the light receiving portion of the optical sensor 14 is detected to determine whether or not the rotating member 19 is located at the initial position, that is, whether or not the light projecting slit is located in the initial position region of the light shielding portion 19l. . When located in the initial position region, it is determined whether or not the ternary display as the sensor signal values of the first and second rotor position detection sensors 171 and 172 is “α: L, β: 0”.

  In FIG. 11B, the light projection slit is located in the first region of the light shielding portion 19l before and after the motor 12 is driven, and is completely exposed from the light shielding portion 19l (the light shielding ratio becomes 0%). ). Therefore, the output of the optical sensor 14 does not change before and after the motor 12 is driven. The output value is a high value because the light shielding ratio is 0%. The ternary display at the rotor stop position of the motor 12 after one-step driving is “α: H, β: 0” at position 8, and the motor energization phase is “A phase: 0, B phase: +”. .

  In FIG. 11C, before the motor 12 is driven, the light projection slit is located in the first region of the light shielding portion 19l and is completely exposed from the light shielding portion 19l (the light shielding ratio becomes 0%). On the other hand, after one-step driving, the light projecting slit is located in the second region of the light shielding unit 191, and a part thereof is shielded from light by the light shielding unit 191. Therefore, the output of the optical sensor 14 decreases before and after the motor 12 is driven. The ternary display at the rotor stop position of the motor 12 after one-step driving is “α: H, β: L” which is position 1, and the motor energization phase is “A phase: +, B phase: +”. . Here, the boundary between the flat wall (first region) and the slope wall (second region) has a slight step in the height direction, so that it is in a light-shielded state when driven by one step across the boundary. Misalignment can be prevented by sharpening changes.

  In FIG. 11D, the light projection slit is located in the third region of the light shielding portion 191 before and after the motor 12 is driven, and the light shielding ratio of the light projection slit of the light shielding portion 191 is 70%. Therefore, the output of the optical sensor 14 does not change before and after the motor 12 is driven. The output value is a low value because the light shielding ratio is 70%. The three-value display at the rotor stop position of the motor 12 after one-step driving is “α: L, β: 0” at position 4, and the motor energization phase is “A phase: 0, B phase: −”. .

  In FIG. 11E, the light projection slit is located in the fourth region of the light shielding unit 191 before and after the motor 12 is driven, and a part of the light projecting slit is shielded by the light shielding unit 191. Since the light shielding part 19l is inclined downwardly to the right, the output of the optical sensor 14 increases before and after the motor 12 is driven. The ternary display at the rotor stop position of the motor 12 after one-step driving is “α: H, β: H” at position 7, and the motor energization phase is “A phase: −, B phase: +”. .

  In FIG. 11F, the light projection slit is located in the fifth region of the light shielding part 191 before and after the motor 12 is driven, and the light shielding ratio of the light projection slit of the light shielding part 191 is 30%. Therefore, the output of the optical sensor 14 does not change before and after the motor 12 is driven. The output value is a medium value because the light shielding ratio is 30%. The ternary display at the rotor stop position of the motor 12 after one-step driving is “α: 0, β: H” at position 6, and the motor energization phase is “A phase: −, B phase: 0”. .

  In FIG. 11G, before the motor 12 is driven, the light projection slit is located in the second region of the light shielding part 19l, and a part thereof is shielded from light by the light shielding part 19l. On the other hand, after one-step driving, the light projection slit is located in the first region of the light shielding portion 191 and is completely exposed from the light shielding portion 19l (the light shielding ratio becomes 0%). Therefore, the output of the optical sensor 14 increases before and after the motor 12 is driven. The ternary display at the rotor stop position of the motor 12 after one-step driving is “α: H, β: 0” at position 8, and the motor energization phase is “A phase: 0, B phase: +”. .

  In FIG. 11 (h), the light projection slit is located in the fourth region of the light shielding unit 191 before and after the motor 12 is driven, and a part thereof is shielded from light by the light shielding unit 191. Since the light-shielding portion 19l is inclined to the lower right (upward to the left), the output of the optical sensor 14 occurs before and after the motor 12 is driven. The ternary display at the rotor stop position of the motor 12 after one-step driving is “α: L, β: L” in position 3, and the motor energization phase is “A phase: +, B phase: −”. .

  As described above, the area of the light shielding portion 191 is determined from the output of the optical sensor 14 before and after the one-step driving of the motor 12, and the position in the area after the driving is output from the first and second rotor position detection sensors 171 and 172. Thus, the absolute position of the rotating member 19 can be calculated.

  Whether to drive one step in the narrowing direction or one step in the opening direction is determined by the light amount change direction (increased or decreased) of the optical apparatus equipped with the light amount adjusting device of this embodiment, and will be described in detail later. .

  The operation of the optical apparatus provided with the light amount adjusting device of this embodiment will be described with reference to the flowchart of FIG. In the present embodiment, the processes of FIGS. 7 to 9 of the first embodiment are common, and only the light amount adjustment process of FIG. 10 is different. Therefore, in this embodiment, only the light amount adjustment process will be described, and the other description will be saved.

  In step S61, light amount adjustment processing is started. In step S62, subject photometry is performed using subject image data captured by the image sensor 23 (different from the photometry method at the time of still image shooting).

  In S63, the photometric value in S62 is compared with the previous value to determine whether there is a change in brightness. If there is a change in brightness, the process proceeds to S64. If there is no change in brightness, the process returns to S62 to perform photometry again. Here, since there is no previous value in the first photometry after starting moving image shooting, the process proceeds to S64 as it is.

  In S64, an appropriate aperture value is calculated based on the photometric value in S62. Here, AE control is performed by combining the control of the light amount adjusting device 200 (control of the aperture value), the electronic shutter of the image sensor 23, and the ISO sensitivity until it can be determined that the exposure (AE) is appropriate. In S <b> 65, the optical sensor 14 detects the output that has passed through the light shielding portion 191 of the rotating member 19.

  In S66, it is determined whether or not the brightness detected in S63 has increased. If the brightness increases, the process proceeds to S67. In S67, the motor 12 is driven one step in the narrowing direction. If the brightness has decreased, the process proceeds to S68, where the motor 12 is driven one step in the opening direction. Since the driving direction of the motor 12 corresponds to the direction of change in brightness, there is little uncomfortable feeling when a captured image is displayed on the monitor.

  In S69, the optical sensor 14 again detects the output that has passed through the light shielding portion 19l of the rotating member 19. In S70, the outputs of the first and second rotor position detection sensors 171 and 172 are ternarized to calculate a ternary position of the rotor stop position of the motor 12. In S71, the absolute position detection circuit 26 compares the output of the optical sensor 14 detected in S65 and S69 to calculate the area of the light shielding portion 19l, and matches the ternary position of the rotor stop position calculated in S70. Thus, the absolute position of the rotating member 19 is calculated. In S72, the required drive amount of the motor 12 is calculated from the ideal position of the rotating member 19 corresponding to the appropriate aperture value calculated in S64 and the current position (absolute position) of the rotating member 19 calculated in S71. After the power is turned on, predetermined driving is performed. After the driving of the motor 12 is completed, the power of the motor 12 is turned off. If the required drive amount is 0, the drive is not performed (there is no need for further drive due to the one-step drive of the motor 12 for detecting the area of the light shielding portion 19l). In S73, the light amount adjustment process is terminated. The light amount adjustment process is repeatedly performed at predetermined time intervals by a predetermined timer.

  As described above, in the light amount adjusting apparatus of this embodiment, the region of the light shielding unit 19l is determined from the output change of the optical sensor 14 when the motor 12 is driven by one step. Then, the absolute position of the rotating member 19 can be calculated by calculating the position in the region from the outputs of the first and second rotor position detection sensors 171 and 172. This is significantly less expensive than general absolute position detection sensors such as optical encoders and linear scales.

  In the first embodiment, the light shielding ratio is divided into six stages. In this embodiment, the light shielding portion 19l is provided with a slope portion so that the region is detected from the output change before and after one step driving. For this reason, it is difficult to be influenced by fluctuations in the output of the optical sensor due to environmental (temperature) changes or the like, and light amount adjustment with higher reliability can be performed.

  Furthermore, since the optical apparatus including the light amount adjusting device of the present embodiment can calculate the absolute position of the rotating member 19, it is necessary to return the motor 12 to the initial position when the motor 12 is turned off and then turned on again. There is no. Therefore, it is possible to turn off the motor 12 when there is no change in the amount of light during moving image shooting, and even in that case, the reliability of light amount adjustment can be ensured.

  Therefore, the present invention can provide a light amount adjusting device that is low in cost, capable of energy saving driving, and has high reliability.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

9, 19 Rotating member (driven member)
9l, 19l light-shielding part (second detection means)
12 Step motor (drive means)
14 Optical sensor (second detection means)
26 Absolute position detection circuit (position calculation means)
100 Light quantity adjustment device 171, 172 Rotor position detection sensor (first detection means)

Claims (9)

Driving means;
First detecting means capable of detecting the position of the driving means;
A driven member driven by the driving means;
Second detection means capable of detecting a region where the driven member is located;
A position where the position of the driven member can be calculated based on the position of the driving means detected by the first detection means and the region where the driven member is detected detected by the second detection means. And a light amount adjusting device.   The number of detection positions of the drive means that can be detected by the first detection means is equal to or greater than the number of detection positions of the drive means in the region where the driven member is detected, which is detected by the second detection means. The light quantity adjusting device according to claim 1. The driving means has a magnet,
3. The light amount adjusting device according to claim 1, wherein the first detection unit includes two magnetic sensors that detect a position of the magnet in order to detect a position of the driving unit.   The second detection unit includes an optical sensor including a light emitting unit and a light receiving unit, and a light shielding unit in which a light shielding region that shields light from the light emitting unit toward the light receiving unit is formed for each of the corresponding regions. The light quantity adjusting device according to any one of claims 1 to 3, wherein   5. The light amount adjustment according to claim 4, wherein the light shielding region of the light shielding unit shields light so that a light shielding ratio of light traveling from the light emitting unit to the light receiving unit is different for each corresponding region of the region. apparatus.   5. The light quantity according to claim 4, wherein the plurality of light shielding regions of the light shielding unit are adjacent to a light shielding region whose light shielding ratio changes according to a position of the driven member and a light shielding region whose light shielding ratio does not change. Adjusting device.   The position calculating means is based on the output of the optical sensor at a first position and the output of the optical sensor at a second position after driving the driven member by a predetermined value. The light quantity adjusting device according to claim 6, wherein a region in which is located is detected.   The light quantity adjusting device according to claim 4, wherein the light shielding portion is formed on the driven member.   An optical apparatus comprising the light amount adjusting device according to any one of claims 1 to 8.