JP2005275177A - Diaphragm device and digital camera using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm device which can have driving noise suppressed regardless of movement of sectors during photographing. <P>SOLUTION: A diaphragm device 1 is provided with sectors 10-1 to 10-5 for opening/closing an aperture 2HL formed in a substrate 2, an electromagnetic actuator 20 for driving the sectors, and a control means 25 for controlling driving of the electromagnetic actuator. The control means 25 executes drive control including a pause step ST of temporarily stopping driving the sectors 10-1 to 10-5 by the electromagnetic actuator during movement of the sectors 10-1 to 10-5 to positions wherein they form an objective diaphragm state. In such a simple configuration that drive control executed by the control means includes the pause step of temporarily stopping driving the sectors by the electromagnetic actuator, noise is restrained from occurring in comparison with the case of continuous driving of the electromagnetic actuator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a diaphragm device used in a digital camera or the like. More specifically, the present invention relates to an aperture device that is optimal for moving image shooting by suppressing the generation of driving sound during driving.

  In recent years, digital cameras have become widespread and their functions have become multifunctional. A moving picture shooting function is added to a digital still camera dedicated to still images. In general, when taking a still image with a still camera, the sector (aperture blade) moves first to form a predetermined aperture state. Then, shooting is performed with the sector stopped at that position. However, when performing moving image shooting, the ambient brightness changes every moment, and it is necessary to adjust the aperture accordingly. Therefore, in the moving image mode, shooting is performed while moving the sector.

  In the above video mode, audio can be recorded simultaneously. However, when a moving image is taken with a digital camera, a driving sound for controlling the diaphragm is generated. There is a problem that this driving sound is picked up by a microphone attached to the camera and reproduced as noise when the recording is reproduced.

  Thus, for example, Patent Document 1 proposes a digital camera that reduces the influence of diaphragm driving sound. This digital camera is provided with control means for controlling the motor so that the driving sound of the diaphragm mechanism is input during the sampling period of the analog audio signal to be recorded. In such a digital still camera, the motor drive is controlled so that the driving sound of the diaphragm mechanism is generated between a certain sampling time and the next sampling time. Therefore, it is possible to prevent the drive sound of the diaphragm drive mechanism from being recorded simultaneously.

Japanese Patent Laid-Open No. 2004-23502

  However, the technique disclosed in Patent Document 1 performs complicated control of driving a motor so that a driving sound is input during a sampling period of an audio signal. This control does not drive the motor during the sampling period, but controls the driving sound generated when the motor is driven during the sampling period, so that the control logic becomes complicated. Further, in the technique of Patent Document 1, when the timing at which the diaphragm mechanism needs to be driven in the moving image mode and the sampling period of the audio signal coincide with each other, the motor is not driven in order to suppress the input of driving sound. It will be. Therefore, the technique proposed in Patent Document 1 may not be able to drive the aperture mechanism in response to changes in ambient brightness.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an aperture device that can suppress the generation of drive sound even if the sector is moved during shooting.

  The object is a diaphragm device comprising a sector that opens and closes an opening formed in a substrate, an electromagnetic actuator that drives the sector, and a control unit that controls the driving of the electromagnetic actuator. In the middle of moving the sector to the position where the aperture state is formed, this can be achieved by an aperture device that performs drive control including a pause step in which the driving of the sector by the electromagnetic actuator is temporarily stopped. According to the present invention, noise generated in comparison with the case where the electromagnetic actuator is continuously driven with a simple configuration in which the drive control executed by the control means includes a pause step for temporarily stopping the driving of the sector by the electromagnetic actuator. Can be suppressed.

Moreover, you may make it the said pause step interrupt | block the electricity supply to the said electromagnetic actuator temporarily. If it does in this way, the heat_generation | fever and power consumption of a coil can be suppressed.
The drive control may include intermittent drive control that alternately repeats a drive step for energizing the electromagnetic actuator and a pause step. That is, the desired aperture state can be formed by moving the sector by intermittent drive in which the drive and pause steps are alternately executed.

  Further, it is preferable that the control means re-drives the electromagnetic actuator after performing an initial setting when the energization to the electromagnetic actuator is cut off. Thus, if the initial setting is performed at the time of re-driving, even if a position shift occurs due to the electromagnetic actuator being stopped, this can be removed. With a digital camera equipped with the aperture device as described above, moving image shooting can be performed while suppressing the influence of the drive sound of the electromagnetic actuator.

  As described above, according to the present invention, it is possible to provide a diaphragm device that suppresses the generation of drive sound by a simple drive control that includes a pause step of temporarily stopping the drive of a sector by an electromagnetic actuator. Further, when the energization of the electromagnetic actuator is temporarily interrupted as a pause step, it is possible to prevent the coil from generating heat and reduce power consumption.

  Hereinafter, a diaphragm device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of main parts of the diaphragm device 1 in a state where the diaphragm opening is fully opened. FIG. 2 is a diagram showing the diaphragm device 1 when the diaphragm aperture is the smallest diaphragm MN. FIG. 3 is a view showing one sector (diaphragm blade) included in the diaphragm device 1.

  In FIG. 1, the diaphragm device 1 includes a substrate 2 on which a circular diaphragm opening 2HL is formed. A diaphragm ring 5 that can rotate in the direction of the arrow RM is disposed so as to be parallel to the surface of the substrate 2. However, in the state shown in FIG. 1, since the position of the aperture ring 5 is located at the end rotated clockwise, the state shown in FIG. 1 is rotated counterclockwise. The aperture ring 5 has a ring opening 5HL at the center. The ring opening 5HL and the aperture opening 2HL of the substrate 2 have substantially the same shape, and the aperture ring 5 is disposed on the substrate 2 so that the apertures overlap each other.

  The aperture device 1 includes five sectors 10-1 to 10-5, and swings with the rotation of the aperture ring 5 to change the aperture of the aperture 2HL. Each of the five sectors 10-1 to 10-5 has a point-symmetric posture with respect to the center point CP of the aperture opening 2HL, and is swung in the same manner by the aperture ring 5 to cooperate with each other. Form a diaphragm.

  On the substrate 2, five fixed shafts 3-1 to 3-5 are provided upright at equal intervals in the circumferential direction. Each of the five sectors 10 swings with the fixed shafts 3-1 to 3-5 as the support shafts. On the other hand, engagement pins 6-1 to 6-5 are erected on the diaphragm ring 5 at equal intervals in the circumferential direction. These engagement pins 6-1 to 6-5 are engaged with cam grooves 11-1 to 11-5 having predetermined shapes formed in the sectors 10-1 to 10-5. Therefore, each engagement pin 6 is moved by the rotation of the aperture ring 5 and slides in each cam groove 11, so that each sector 10 swings along a predetermined locus.

  FIG. 2 is a diagram showing a case where the diaphragm ring 5 is rotated counterclockwise from the fully opened diaphragm shown in FIG. 1 to obtain the smallest diaphragm state. In FIG. 2, the position of the small aperture 2MN is shown by hatching so that the aperture that has been narrowed down can be easily confirmed. FIG. 3 shows a state in which one sector 10-1 included in the diaphragm device 1 is taken out and swings when the diaphragm ring 5 rotates from the state of FIG. 1 to the state of FIG. It is a figure. 3, it can be confirmed that when the engagement pin 6-1 moves counterclockwise by the rotation of the aperture ring 5, the sector 10-1 swings clockwise about the fixed shaft 3-1. Since the other sectors 10-2 to 10-5 operate in the same manner, the diaphragm opening 2HL can be narrowed as shown in FIG.

  With reference to FIG. 1 again, the configuration of the drive system of the diaphragm device 1 will be described. When changing the aperture as described above, the aperture ring 5 is rotated. The aperture ring 5 includes a protruding portion 5PR that protrudes in the radial direction. A tooth row 5GA is formed at the tip of the protruding portion 5PR. This tooth row 5GA meshes with a wheel train 15 driven by a rotor kana 21 of a step motor 20 as an electromagnetic actuator. The drive of the step motor 20 is controlled by a control unit 25 serving as control means. Therefore, when the aperture device 1 is incorporated in a camera and used, the control unit 25 receives a predetermined aperture signal from the camera side, and controls the step motor 20 based on this to rotate the aperture ring 5, Each sector 10 is moved to a predetermined position to form the desired aperture. As shown in FIG. 1, the control unit 25 controls the drive of the step motor 20 by switching the current supplied to the two drive coils CA and CB wound around the stator disposed in the step motor 20. I do.

  In particular, the control unit 25 included in the diaphragm device 1 includes an excellent feature of driving the step motor 20 so as to suppress the generation of drive sound when moving the sector in the moving image mode. Hereinafter, control of the step motor 20 by the control unit 25 will be described. In the moving image mode, the image to be taken changes every moment. Accordingly, it is necessary to change the aperture state, that is, the position of the sector 10. For example, when an image becomes dark during photographing, it is necessary to move the sector 10 to the side where the aperture is increased. Further, after that, when the photographed image becomes brighter, it is necessary to move the sector 10 to the side where the aperture is reduced. Thus, in the moving image mode, the state of the target aperture (a preferable aperture for photographing) changes every moment. Then, the sector 10 is continuously moved so as to successively form a preferable throttle state that changes in this way. Therefore, in the past, drive noise was generated as pointed out earlier.

  FIG. 4 is a diagram showing a pattern example in which the coils CA and CB of the step motor 20 are excited when the sector 10 located at a certain position is moved to form a desired aperture state. That is, FIG. 4 can be regarded as showing an example of a control pattern of the current supplied from the control unit 25 to the coils CA and CB. Note that Av shown in FIG. 4 represents a predetermined aperture value. Specifically, the aperture area is set to approximately double when the aperture is opened by 1 Av, and conversely, the aperture area is approximately halved when the aperture is reduced by 1 Av.

  FIG. 4 shows an example of an excitation pattern in the case where the aperture is changed to a small aperture in the upper stage (the aperture value is decreased), that is, when each sector 10 is moved from the state of FIG. 1 to the state of FIG. . On the contrary, in the lower stage, on the contrary, when the aperture is changed to a large aperture (the aperture value is increased), that is, when each sector 10 is moved from the state of FIG. 2 to the state of FIG. Is shown. Each of the upper and lower stages shown in FIG. 4 shows an example in which the target aperture state is changed by 2/3 Av from the original state.

  It should be noted in FIG. 4 that a pause step ST is inserted between the operation (driving step) for changing the aperture value of 1/3 Av first and the operation for changing the 1/3 Av value next. Is a point. In the rest step ST, energization to both the coils CA and CB is interrupted. That is, in the pause step ST, the driving of the step motor 20 is stopped. If the coils CA and CB are driven to move each sector 10 with an excitation pattern including at least one pause step ST as shown in FIG.

  FIG. 5 is a diagram showing excitation patterns of the coils CA and CB when the respective sectors 10 are moved within the same range as in FIG. That is, FIG. 5 does not include the pause step ST of FIG. 4, and the sector 10 is moved so that the aperture value of 2/3 Av continuously changes. However, in FIG. 5, a range corresponding to the aperture value of 1/3 Av and a place where the pause step ST is inserted are denoted by reference symbol SP so that the difference from FIG. 4 can be confirmed.

  When the inventor of the present application provides the pause step ST as shown in FIG. 4, the driving noise is reduced by about 5 dB as compared with the case where the sector 10 is moved by continuously energizing as in the prior art (see FIG. 5). Confirmed that it can be reduced. A graph is shown in FIG. The horizontal axis represents the pause time of the pause step ST, and the vertical axis represents the noise reduction value. As shown in the graph, if the pause step ST is taken for a long time, the noise value is lowered accordingly. However, if the pause step ST is taken for a long time, it takes too much time for the sector to move. In the present embodiment, a pause time of about 80 to 90 ms is provided as the pause step ST. In this way, the diaphragm blades can be driven in a time that is not much different from the drive time of the diaphragm of the conventional diaphragm device, and the noise is also small. That is, in the present diaphragm device 1, noise generation can be suppressed by about 35% as compared with the prior art by a simple control of inserting a pause step that temporarily stops the driving of the step motor 20 when changing the diaphragm. In addition, since the coil is not energized during the pause step, the heat generation of the coil can be suppressed. In addition, power consumption is reduced.

  Note that FIG. 4 shows an example in which one pause step ST is inserted between 1/3 Av value aperture operations when the aperture value is changed by 2/3 Av, but this is only an example. When the aperture value to be changed is large, the pause step ST may be set twice or more and intermittently driven. In addition, the aperture value to be changed in one operation may be changed as appropriate, and the target aperture value may be set with a different value without being divided equally. Further, since the energization to the step motor 20 is interrupted in the pause step ST, the position of the step motor 20 may change from the initial setting adjusted by the initial initial excitation. Therefore, as shown in FIG. 4, when the next 1/3 Av operation is started (when re-driving), it is desirable to perform the initial excitation PR again before substantially driving the step motor 20. 4 shows an example in which the energization is turned off in the pause step, the hold motor may be energized during the pause step to temporarily stop the step motor 20.

  FIG. 4 shows an example in which the step motor 20 is driven by 1-2 phase excitation, but it goes without saying that the generation of drive sound can be similarly suppressed when the step motor 20 is driven by two phase excitation. . The diaphragm device 1 described above can suppress the generation of driving sound even when the sector 10 continuously moves by simply controlling the step motor 20. Therefore, a digital camera incorporating such an aperture device 1 can capture a moving image while suppressing noise generation in the moving image mode.

  The preferred embodiment of the present invention has been described in detail above. However, the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the gist of the present invention described in the claims. Deformation / change is possible.

It is the figure which showed the principal part structure of the aperture_diaphragm | restriction apparatus in the state which made the aperture opening fully open. It is the figure which showed the aperture_diaphragm | restriction apparatus when an aperture opening is made into the minimum aperture_diaphragm | restriction MN. It is the figure which took out and showed one sector included in a diaphragm | throttle device. It is the figure which showed the example of a pattern which excites the coil of the step motor included in a diaphragm | throttle device. FIG. 5 is a diagram showing a coil excitation pattern when a sector is moved within the same range as in FIG. It is a figure showing the relationship between the rest time of the rest step ST and the noise reduction value.

Explanation of symbols

1 Diaphragm 2 Substrate 2HL Aperture Opening 5 Diaphragm Ring 10 Sector 20 Step Motor 25 Control Unit ST Rest Step PR Initial Excitation

Claims (5)

A diaphragm device comprising a sector that opens and closes an opening formed in a substrate, an electromagnetic actuator that drives the sector, and a control unit that controls the driving of the electromagnetic actuator,
The control means executes drive control including a pause step for temporarily stopping driving of the sector by the electromagnetic actuator while moving the sector to a position where a desired aperture state is formed. Squeezing device to do. The aperture device according to claim 1, wherein the suspension step temporarily interrupts energization of the electromagnetic actuator. 3. The diaphragm device according to claim 1, wherein the drive control includes intermittent drive control that alternately repeats a drive step of energizing the electromagnetic actuator and the pause step. 4. 4. The aperture device according to claim 1, wherein the control unit re-drives the electromagnetic actuator after performing an initial setting when the energization to the electromagnetic actuator is cut off. 5. A digital camera capable of shooting a moving image, comprising the aperture device according to any one of claims 1 to 4.

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