WO2005094065A1

WO2005094065A1 - Diaphragm and digital camera using the same

Info

Publication number: WO2005094065A1
Application number: PCT/JP2005/005145
Authority: WO
Inventors: Seiichi Oishi; Hiroyuki Koizumi; Eiji Tanaka; Satoru Tada; Hideki Tanaka
Original assignee: Seiko Precision Inc.
Priority date: 2004-03-25
Filing date: 2005-03-22
Publication date: 2005-10-06
Also published as: TW200540556A; JP4908741B2; JP2005275177A; TWI264613B

Abstract

A diaphragm (1) includes: sectors (10-1 to 10-5) for opening/closing an opening (2HL) formed in a substrate (2); an electromagnetic actuator (20) driving the sectors; and control means (25) for controlling drive of the electromagnetic actuator. The control means (25) executes drive control containing a stop step ST for temporarily stopping drive of the sectors (10-1 to 10-5) by the electromagnetic actuator during a process of moving the sectors (10-1 to 10-5) to the position for forming a target diaphragm state. According to the present invention, by the simple configuration that the control means has a stop step for temporarily stopping drive of the sectors by the electromagnetic actuator, it is possible to suppress the noise as compared to the case when the electromagnetic actuator is continuously driven.

Description

Specification

Aperture device and digital camera using the same

Technical field

The present invention relates to an aperture device used in a digital camera or the like. More specifically, the present invention relates to an aperture device that suppresses generation of driving noise during driving and is optimal for moving image (movie) mode shooting. Background art

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

[0003] In the moving image mode described above, sound can be recorded simultaneously. However, when a moving image is shot with a digital camera, a drive sound for controlling the aperture is generated. There is a problem that this driving noise is picked up by the microphone attached to the camera and is reproduced as noise when the recorded image is reproduced.

[0004] Therefore, for example, Patent Document 1 proposes a digital camera that reduces the influence of the drive sound of the aperture. This digital camera is provided with control means for controlling the motor so that the driving sound of the aperture 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 drive sound of the aperture mechanism is generated between a certain sampling time and the next sampling time. Therefore, it is possible to prevent the drive sound of the aperture drive mechanism from being recorded simultaneously.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-23502

Disclosure of the invention

Problems to be solved by the invention

[0006] However, the technology disclosed in Patent Document 1 performs complicated control of driving a motor so that driving sound is input during a sampling period of an audio signal. This control is Rather than driving the motor during the pulling cycle, the control logic makes the driving noise generated when the motor is driven into the sampling cycle, so that the control logic becomes complicated. In the technique of Patent Document 1, when the timing at which it is necessary to drive the aperture mechanism in the moving image mode and the sampling period of the audio signal coincide with each other, the motor is controlled in order to suppress the driving noise. It will not be driven. Therefore, the technique proposed in Patent Document 1 may not be able to drive the aperture mechanism in response to a change in ambient brightness.

[0007] Therefore, an object of the present invention is to provide an aperture device that can suppress generation of driving noise even when a sector is moved during shooting.

Means for solving the problem

[0008] The above object is a throttle device comprising: a sector for opening and closing an opening formed in a substrate; an electromagnetic actuator for driving the sector; and control means for controlling driving of the electromagnetic actuator. The means can be achieved by a diaphragm device that executes drive control including a pause step of temporarily stopping the driving of the sector by the electromagnetic actuator while moving the sector to a position where a desired diaphragm state is formed. . According to the present invention, the drive control executed by the control means has a simple configuration in which a pause step for temporarily stopping the drive of the sector by the electromagnetic actuator is included. Noise can be reduced.

[0009] The suspending step may temporarily interrupt energization to the electromagnetic actuator. By doing so, heat generation and power consumption of the coil can be suppressed. The drive control may include an intermittent drive control in which a drive step of energizing the electromagnetic actuator and the pause step are alternately repeated. In other words, it is possible to move the sector by intermittent driving that alternately executes the steps of driving and pausing, thereby forming a desired aperture state.

[0010] Further, it is preferable that the control means, when the energization of the electromagnetic actuator is cut off, perform an initial setting and then re-drive the electromagnetic actuator. By performing the initial setting at the time of re-driving in this way, even if a position shift occurs due to the stop of the electromagnetic actuator, it can be eliminated. With a digital camera provided with the above-described aperture device, it is possible to capture a moving image while suppressing the influence of the driving sound of the electromagnetic actuator. The invention's effect

[0011] As described above, it is possible to provide the aperture device according to the present invention in which the generation of driving noise is suppressed by a simple driving control including a pause step of temporarily stopping the driving of the sector by the electromagnetic actuator. Also, when the power to the electromagnetic actuator is temporarily cut off as a pause step, heat generation of the coil can be prevented and power consumption can be reduced.

Brief Description of Drawings

FIG. 1 is a diagram showing a main part configuration of a diaphragm device in a state where a diaphragm aperture is fully opened.

FIG. 2 is a diagram showing a diaphragm device when a diaphragm aperture is a minimum diaphragm MN.

FIG. 3 is a view showing one sector included in the aperture device.

FIG. 4 is a diagram showing an example of a pattern for exciting a coil of a step motor included in a diaphragm device.

FIG. 5 is a diagram showing a coil excitation pattern when the sector is moved in the same range as in FIG. 4 by continuous energization as in the related art.

FIG. 6 is a diagram showing a relationship between a pause time of a pause step ST and a noise reduction value.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an aperture device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main configuration 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 set to the minimum diaphragm MN. FIG. 3 is a view showing one sector (aperture 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. An aperture ring 5 rotatable in the direction of arrow RM is provided so as to be parallel to the surface of the substrate 2. However, the state shown in FIG. 1 is rotated counterclockwise from the state shown in FIG. 1 since the position of the aperture ring 5 is located at the end rotated clockwise. The aperture ring 5 has a ring opening 5HL at the center. The ring opening 5HL and the stop opening 2HL of the substrate 2 have substantially the same shape, and the stop ring 5 is arranged on the substrate 2 such that the openings overlap.

[0015] The aperture device 1 includes five sectors 10-1 10-5, and swings in accordance with the rotation of the aperture ring 5 to change the opening degree of the aperture opening 2HL. 5 sectors 10—1— 10—5 Each of them has a point symmetry with respect to the center point CP of the aperture opening 2HL, and is similarly swung by the aperture ring 5 to cooperate to form a predetermined aperture.

[0016] 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 about the fixed axis 3-1, 3-5. On the other hand, engaging pins 6-1-6-5 are also provided on the drawing ring 5 at equal intervals in the circumferential direction. These engagement pins 6-1-6-5 are engaged with cam grooves 11-1-11-11_5 of a predetermined shape formed in the sectors 10-1-10-5. Accordingly, the rotation of the aperture ring 5 moves each engagement pin 6 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 aperture ring 5 is rotated counterclockwise from the fully opened aperture shown in FIG. 1 to the smallest aperture state. In FIG. 2, the position of the small aperture opening 2MN is hatched so that the narrowed aperture can be easily checked. FIG. 3 shows a state in which one sector 10-1 included in the aperture device 1 is taken out and the aperture ring 5 swings when rotating from the state of FIG. 1 to the state of FIG. FIG. From FIG. 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. The other sectors 10-2-10-5 operate in the same manner, so that the aperture 2HL can be reduced as shown in FIG.

The configuration of the drive system of the diaphragm device 1 will be described again with reference to FIG. When the aperture is changed as described above, the aperture ring 5 is rotated. The aperture ring 5 has a protruding portion 5PR that protrudes in the radial direction. A tooth row 5GA is formed at the tip of the protrusion 5PR. The gear train 5GA is combined with a wheel train 15 driven by a rotor pinion 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 stepping motor 20 based on the signal to rotate the aperture ring 5. Then, each sector 10 is moved to a predetermined position to form a target aperture. As shown in FIG. 1, the control unit 25 switches the current supplied to the two drive coils CA and CB wound around the stator disposed in the step motor 20 to drive the step motor 20. Perform control.

[0019] In particular, the control unit 25 included in the aperture device 1 moves the sector in the moving image mode. In this case, the stepping motor 20 is driven so as to suppress generation of driving noise. Hereinafter, control of the step motor 20 by the control unit 25 will be described. In the moving image mode, the image to be shot changes every moment. Accordingly, it is necessary to change the state of the aperture, that is, the position of the sector 10. For example, if the image becomes darker during shooting, it is necessary to move the sector 10 to the side where the aperture is increased. Furthermore, when the captured image becomes brighter thereafter, 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 preferred aperture for shooting) changes every moment. Then, the sector 10 is continuously moved so as to successively form such changing preferred aperture states. As a result, drive noise was generated in the past, as pointed out earlier.

FIG. 4 is a diagram showing an example of a pattern for exciting the coils CA and CB of the step motor 20 when the sector 10 located at a certain position is moved to form a target aperture state. That is, it can be seen that FIG. 4 shows 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 ΙΑν, and conversely, the aperture area is set to approximately 1/2 when the aperture is stopped by 込む ν.

FIG. 4 shows an example of the excitation pattern when the aperture is changed to a small aperture at the upper stage (the aperture value is reduced), that is, when each sector 10 is moved from the state of FIG. 1 to the state of FIG. Is shown. On the other hand, in the lower part, on the contrary, the excitation pattern 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. An example is shown. The upper and lower rows shown in FIG. 4 both show examples in which the target aperture state is changed by 2Z3Av from the original state.

It should be noted in FIG. 4 that a pause step ST is inserted between the operation of changing the aperture value of l / 3Av (drive step) and the operation of changing the lZ3Av value first. That is. In this pause step ST, the power supply to both coils CA and CB is cut off. That is, in the pause step ST, the drive of the step motor 20 is stopped. By driving the coils CA and CB to move each sector 10 in an excitation pattern including at least one pause step ST as shown in Fig. 4, noise can be greatly reduced. FIG. 5 is a diagram showing the excitation patterns of the coils CA and CB when the current is continuously applied and the respective sectors 10 are moved in 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 changes continuously. However, in FIG. 5, the range corresponding to the aperture value of each l / 3Av and the place where the pause step ST is inserted are denoted by reference numerals SP, and are illustrated and checked so that differences from FIG. 4 can be confirmed.

[0024] The inventors of the present invention have provided a pause step ST as shown in Fig. 4, by about 5 dB compared to a conventional case where the sector 10 is moved by continuous energization (see Fig. 5). It was confirmed that driving noise could be reduced. Figure 6 shows the graph. 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, the longer the pause step ST is taken, the lower the noise level becomes. The longer the pause step ST takes, the longer it takes to move the sector. 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 driving time of the diaphragm of the conventional diaphragm device, and the noise is reduced. That is, the diaphragm device 1 can suppress the generation of noise by about 35% as compared with the conventional one by a simple control in which the stop of the step motor 20 is temporarily stopped when the diaphragm is changed. In addition, since no power is supplied during the pause step, the coil can generate heat S. Also, power consumption is reduced.

FIG. 4 shows an example in which one stop step ST is inserted between 1/3 Av value aperture operations in the case of changing the aperture value by 2/3 Av. This is an example. If the aperture value to be changed is large, the pause step ST may be set at least twice and intermittent drive may be repeated. In addition, the aperture value changed in one operation may be changed as appropriate, and a different aperture value may be set without dividing the target aperture value equally. Further, since the energization of the idle step ST In stearyl Ppumota ₂₀ is interrupted, there is a case where the initial setting force adjusted by the initial initial excitation, the position of al the step motor 20 is changed. Therefore, when the next 1/3 Av operation is started (when re-driving) as shown in FIG. 4, it is desirable to perform the initial excitation PR again to substantially drive the force step motor 20. Also, Fig. 4 shows an example in which the energization is turned off in the pause step. Alternatively, the step motor 20 may be temporarily stopped.

FIG. 4 shows a case where the step motor 20 is driven by 1_2-phase excitation as an example. However, when the step motor 20 is driven by two-phase excitation, the generation of driving noise can be similarly suppressed. Needless to say. The diaphragm device 1 described above can suppress the generation of driving noise even when the sector 10 moves continuously by simply controlling the step motor 20. Therefore, a digital camera incorporating such an aperture device 1 can capture a moving image while suppressing the generation of noise in the moving image mode.

As described above, a preferred embodiment of the present invention has been described in detail. However, the present invention is not limited to the specific embodiment, but may be embraced within the scope of the present invention described in the appended claims. Various modifications and changes are possible.

Claims

The scope of the claims

[1] A diaphragm device comprising: a sector for opening and closing an opening formed in a substrate; an electromagnetic actuator for driving the sector; and control means for controlling the driving of the electromagnetic actuator. A diaphragm device which performs drive control including a pause step for temporarily stopping the drive of the sector by the electromagnetic actuator while moving the sector to a position where a state is formed.

[2] The diaphragm device according to claim 1, wherein the pause step is a step of temporarily interrupting energization to the electromagnetic actuator.

3. The aperture device according to claim 1, wherein the drive control includes an intermittent drive control that alternately repeats a drive step of energizing the electromagnetic actuator and the pause step.

[4] The control device according to any one of claims 1 to 3, wherein when the power supply to the electromagnetic actuator is cut off, the control means performs an initial setting and then drives the electromagnetic actuator again. The squeezing device as described.

[5] A digital camera capable of shooting a moving image, comprising the aperture device according to any one of claims 1 to 4.