JP2009175596A - Motor-driven diaphragm device and driving method for motor-driven diaphragm device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-driven diaphragm device capable of accurately positioning a diaphragm blade at an initial position and a driving method therefor. <P>SOLUTION: The motor-driven diaphragm device is equipped with: the diaphragm blade 4 making the size of an aperture variable; a driving means 5 taking a plurality of excitation states and driving the diaphragm blade between the initial position P0 and a stop-down position Pf where the size of the aperture is restricted; a control means 250 outputting a driving signal to the driving means so as to change the excitation state; and a storage means 250 storing the excitation state of the driving means at the initial position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric diaphragm device and a method for selecting an excitation state thereof.

An electric diaphragm device that drives a diaphragm blade using a pulse motor is known (Patent Document 1). In this electric diaphragm device, when the power switch of the camera is turned on, the diaphragm blades are once driven from the initial position to the reference position and then returned to the initial position. When the release button is pressed, the diaphragm blade is driven from the initial position to the narrowing position.

Utility Model Registration No. 2586964

However, the electric diaphragm device has a problem that an error occurs in the stop position as the initial position, and the accuracy of the diaphragm aperture is lowered.

The problem to be solved by the present invention is to provide an electric diaphragm device that can accurately position the diaphragm blades at the initial position and a driving method thereof.

  The present invention solves the above problems by the following means. In addition, although the code | symbol corresponding to drawing which shows embodiment of this invention is attached | subjected and demonstrated, this code | symbol is only for making an understanding of this invention easy, and is not the meaning which limits this invention.

[1] An electric diaphragm device (220) according to the present invention includes a diaphragm blade (4) having a variable opening size,
Driving means (5) for taking a plurality of excitation states and driving the diaphragm blades between an initial position (P0) and a narrowing position (Pf) for limiting the size of the opening;
Control means (250) for outputting a drive signal to the drive means to change the excitation state;
Storage means (250) for storing the excitation state of the drive means at the initial position.

In the electric throttle device according to the above invention,
Detecting means (6) for detecting that the aperture blade is positioned at a reference position (Ps) that is a predetermined drive distance away from the initial position between the initial position and the aperture position;
The control unit is configured to drive the diaphragm blade from the reference position detected by the detection unit toward the initial position by the predetermined driving amount, and then set the driving unit to an excitation state stored in the storage unit. can do.

In the electric diaphragm apparatus according to the above invention, a stepping motor can be used as the driving means.

[2] A lens barrel according to the present invention includes the electric diaphragm device according to the invention. Further, an imaging apparatus according to the present invention includes the electric diaphragm device according to the above invention.

[3] In the driving method of the electric diaphragm device according to the present invention, the driving is performed by outputting a driving signal at a predetermined first time interval (t1) to the driving means (5) for driving the diaphragm blade (4). A driving method of an electric diaphragm device (220) for driving the diaphragm blades between a narrowing position (Pf) and an initial position (P0) by changing an excitation state of the means,
A first step of outputting the driving signal to the driving means at a second time interval (t2) longer than the first time interval, and driving the diaphragm blades from the narrowed position toward the initial position;
A second step of detecting that the aperture blade has reached a reference position (Ps) set between the aperture position and the initial position;
By outputting a driving signal corresponding to the interval between the reference position and the initial position to the driving means at the second time interval from the time when the diaphragm blade reaches the reference position, the diaphragm blades are moved to the initial position. A third step of stopping at the position;
And a fourth step of storing the excitation state of the driving means when stopped at the initial position as an excitation state corresponding to the initial position.

In the driving method of the electric diaphragm device according to the above invention,
Prior to the first step,
Driving the diaphragm blades toward the reference position by outputting the drive signal to the drive means at the first time interval;
The diaphragm blades are driven from the reference position to the narrowing position by outputting the drive signal at the first time interval to the driving means after the diaphragm blades reach the reference position. can do.

  According to the present invention, it is possible to accurately position the aperture blade at the initial position.

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

FIG. 1 is a main part configuration diagram showing a digital camera C according to an embodiment of the present invention. A digital camera C according to the present embodiment (hereinafter simply referred to as camera C) includes a camera body 100 and a lens barrel 200, and the camera body 100 and the lens barrel 200 are detachably coupled by a mount unit 300. .

The lens barrel 200 incorporates a photographing optical system including a focus lens 211 and other lens groups 210 and a diaphragm device 220.

The focus lens 32 is provided so as to be movable along the optical axis of the light beam L1 of the lens barrel 200, and its position is adjusted by the lens driving motor 230 while its position is detected by the encoder. The focus lens 211 can move in the direction of the optical axis L1 from the end on the camera body side (closest end) to the end on the subject side (infinite end) by the rotation of the rotating cylinder. Incidentally, the current position information of the focus lens 211 detected by the encoder is transmitted to the lens drive control unit 165 described later via the lens control unit 250, and the lens drive motor 230 calculates the focus lens calculated based on this information. The drive position 211 is driven by a command signal received from the lens drive control unit 165 via the lens control unit 250.

  The aperture device 220 is configured such that the aperture diameter around the optical axis L1 can be adjusted in order to limit the amount of light beam that passes through the imaging optical system and reaches the image sensor 110 and to adjust the blur amount. . The adjustment of the aperture diameter by the diaphragm device 220 is performed by transmitting an appropriate aperture diameter calculated in the automatic exposure mode from the camera control unit 170 via the lens control unit 250, for example. The aperture diameter is also adjusted by inputting the set aperture diameter from the camera control unit 170 to the lens control unit 250 by a manual operation by the operation unit 150 provided in the camera body 100. Details of the diaphragm device 220 will be described later.

On the other hand, the camera body 100 includes a mirror system 120 for guiding the light beam L1 from the subject to the image sensor 110, the observation optical system 130, and the focus detection optical module 161. The mirror system 120 includes a main mirror 121 that rotates about a rotation axis O by a predetermined angle between a subject observation position and a photographing position, and a sub mirror 122 that is fixed to the main mirror 121 and rotates integrally with the main mirror 121. With.

In FIG. 1, a state where the mirror system 120 is at the observation position of the subject is indicated by a solid line, and a state where the mirror system 120 is at the photographing position of the subject is indicated by a two-dot chain line. The mirror system 120 is inserted on the optical path of the light beam L1 in the state where the subject is in the observation position, while rotating to retract from the optical path of the light beam L1 in the state where the subject is in the photographing position.

The main mirror 121 is composed of a half mirror, and in a state where the subject is in the observation position, a part of the light beam L2 from the subject is reflected by the main mirror 121 and guided to the observation optical system 130, and a part of the light beam is reflected. L4 is transmitted and guided to the sub mirror 122. On the other hand, the sub mirror 122 is constituted by a total reflection mirror, and guides the light beam L4 transmitted through the main mirror 121 to the focus detection optical module 161. Note that the focus detection optical module 161 performs automatic focusing control by a phase difference detection method using subject light.

Therefore, when the mirror system 120 is at the observation position, the light beam L1 from the subject is guided to the observation optical system 130 and the focus detection optical module 161, and the subject is observed by the user and the focus adjustment of the focus lens 211 is performed. State detection is performed. When the user presses a release button (not shown), the mirror system 120 rotates to the shooting position, and all the light flux L1 from the subject is guided to the image sensor 110, and the shot image data is stored in a memory (not shown).

The image sensor 110 is fixed on the camera body 100 at a position on the optical axis of the light beam L1 from the subject, which is the planned focal plane of the photographing optical system 210. The imaging element 110 is a two-dimensional array of a plurality of photoelectric conversion elements, and can be configured by a two-dimensional CCD image sensor, a MOS sensor, a CID, or the like. The electrical image signal photoelectrically converted by the image sensor 110 is subjected to image processing by the camera control unit 170 and then stored in a memory (not shown). Note that the memory for storing the photographed image can be constituted by a built-in memory or a card-type memory.

On the other hand, part of the subject light reflected by the half mirror 121 is guided to the pentaprism 132 through the finder screen 131 disposed on a surface optically equivalent to the image sensor 110, and bent by the pentaprism 132. After that, it passes through the eyepiece 133 along the optical axis L2 and is guided to the photographer's eyeball. As a result, the subject and its background can be observed through the finder 134 in a state where the release is not performed.

A photometric lens 135 and a photometric sensor 136 are provided in the vicinity of the eyepiece 133, and part of the subject light reflected by the half mirror 121 is imaged on the finder screen 131 and then guided to the pentaprism 132. After being bent by the pentaprism 132, the light is guided to the photometric sensor 136 along the optical axis L3.

The photometric sensor 136 is composed of a two-dimensional color CCD image sensor or the like, detects the brightness of the image to calculate the exposure value at the time of shooting, and detects the subject image at the time of the automatic tracking operation as necessary. . Image information detected by the photometric sensor 136 is output to the camera control unit 170 and used for automatic exposure control and subject tracking control.

The focus detection optical module 161 is a phase difference type focus detection element, which is on the optical axis of the light beam L4 reflected by the sub mirror 122 of the camera body 100 and is optically equivalent to the image pickup surface of the image pickup element 110. The position is fixed. Although not shown in detail, the focus detection optical module 161 includes a converter lens, a diaphragm mask having a pair of apertures, a pair of re-imaging lenses, and a pair of line sensors. Two partial light fluxes are taken out of the image, and the focus state is detected based on the difference in the imaging position of each partial light flux.

The AF-CCD control unit 162 controls the gain and accumulation time of the line sensor of the focus detection optical module 161 in the autofocus mode, and receives information on the focus detection area selected as the focus detection position from the camera control unit 170. The pair of output patterns detected by the pair of line sensors corresponding to the focus detection area are read out and output to the defocus calculation unit 162.

The defocus calculation unit 162 calculates a deviation amount (defocus amount ΔW) of the output pattern from the pair of output patterns sent from the AF-CCD control unit 162, and outputs this to the lens drive amount calculation unit 164. .

Based on the defocus amount ΔW sent from the defocus calculation unit 163, the lens drive amount calculation unit 164 calculates a lens drive amount Δd for making the defocus amount ΔW zero, and performs lens drive control on this. To the unit 165.

The lens drive control unit 165 sends a drive command to the lens drive motor 230 while taking in the lens drive amount Δd sent from the lens drive amount calculation unit 164, and moves the focus lens 211 by the lens drive amount Δd.

The camera body 100 is provided with a camera control unit 170. The camera control unit 170 is electrically connected to the lens control unit 250 through an electrical signal contact unit provided in the mount unit 300, receives lens information from the lens control unit 250, and defocuses to the lens control unit 250. And information such as aperture diameter. The camera control unit 170 reads out image information from the image sensor 110 as described above, performs predetermined information processing as necessary, and outputs the information to a memory (not shown). The camera control unit 170 controls the entire camera C such as correction of captured image information and detection of the focus adjustment state and the aperture adjustment state of the lens barrel 200.

The operation unit 150 is a shutter relay button or an input switch for the user to set various operation modes of the camera C. The auto-focus mode / manual focus mode is switched or the one-shot mode / continuous mode is selected even in the auto-focus mode. The as mode can be switched. Here, the one-shot mode is a mode in which the focus position once adjusted is fixed, and shooting is performed at the focus position. On the other hand, the continuous mode is a focus in accordance with the subject without fixing the focus position. This is a mode for adjusting the position. Various modes set by the operation unit 150 are transmitted to the camera control unit 170, and the operation of the entire camera C is controlled by the camera control unit 170.

  Next, the electric diaphragm device 220 according to the present embodiment will be described.

  2 is a perspective view showing an assembled state of the electric diaphragm device 220 of this example, FIG. 3 is an exploded perspective view of the same, and FIG. 4 is a front view of a rotating member showing a driving position of the diaphragm blades.

  As shown in FIGS. 2 and 3, the electric diaphragm device 220 of the present embodiment (hereinafter also simply referred to as a diaphragm device) is a fixing member 1 that is fixed to a fixed cylinder (frame) of the lens barrel 200 with a bolt or the like. A cam member 3 fixed to the fixing member 1 with a bolt or the like, a rotating member 2 sandwiched between the fixing member 1 and the cam member 3 and rotating in both directions by a predetermined angle, and the rotating member 2 And a plurality of aperture blades 4 that are mounted between the cam member 3 and open and close as the rotary member 2 rotates, and a stepping motor 5 that is attached to the fixed member and serves as a drive source for the rotary member 2 (the aperture shown in FIG. 1). And a photo interrupter 6 that is attached to the fixed member 1 and detects the position of the rotating member 2 in the rotational direction.

  An opening 11 having a larger diameter than the fixed aperture 31 of the cam member 3 is formed in the center of the fixing member 1, and the annular protrusion 21 of the rotating member 2 is rotatably fitted in the opening 11. The rotating member 2 can be smoothly rotated in both directions while being supported by the fixed member 1.

  The pinion gear 51 of the stepping motor 5 attached to the fixed member 1 is inserted into the through hole 12 formed in the fixed member 1, while the segment gear 22 formed on the edge of the rotating member 2 is formed on the fixed member. Is inserted into the circular arc-shaped through hole 13. The pinion gear 51 and the segment gear 22 mesh with each other in the through holes 12 and 13, and the rotation of the stepping motor 5 is transmitted to the rotating member 2.

  A light shielding plate 23 erected on the rotating member 2 is inserted into the arc-shaped through hole 14 formed in the fixing member 1, and as shown in the lower left circle of FIG. When the light shielding plate 23 rotates along the arc-shaped through hole 14, the detection light of the photo interrupter 6 is blocked at a predetermined position. Thereby, the reference position Ps of the rotating member 2 is detected. Details of this will be described later. The diagram in the lower left circle of the figure is a perspective view showing the positional relationship between the photo interrupter 6 and the light shielding plate 23 in a state where the fixing member 1 and the rotating member 2 are assembled, and in the figure, the arrow indicates the light shielding. The moving direction of the plate 23 is shown, and the alternate long and short dash line shows the optical axis of the detection light of the photo interrupter 6.

  On the other hand, the curved wedge-shaped diaphragm blade 4 in which the inner peripheral edge 43 constitutes the diaphragm opening has protrusions 41 and 42 formed on both surfaces of the base end. The protrusion 41 on the rotating member 2 side is inserted into the circular hole 24 formed on the rotating member 2, while the protrusion 42 on the cam member 3 side is a long hole-shaped cam groove formed on the cam member 3. 31 is inserted. When the rotating member 2 rotates in either direction, the protruding portion 41 on the rotating member 2 side rotates (circular locus) together with the rotating member 2, but the protruding portion 42 on the cam member 3 side has the shape of the cam groove 31. Since the following path is followed, the diaphragm blade 4 rotates on the rotating member 2 by a predetermined angle around the protrusion 41.

  In the present embodiment, nine diaphragm blades 4 are mounted at equal intervals along the entire circumference of the rotating member 2. FIG. 4 is a front view showing nine diaphragm blades 4 attached to the cam member 3. FIG. 4A shows a state in which the diaphragm blades 4 are at the initial position P0, and FIG. Is the reference position Ps, and FIG. 5C shows the state where the diaphragm blades 4 are in the narrowed position Pf. In this drawing, when the diaphragm blade 4 (that is, the rotating member 2) rotates clockwise with respect to the cam member 3, the diaphragm becomes smaller (see (A) → (C) in the figure), and conversely with respect to the cam member 3. When the aperture blade 4 (that is, the rotating member 2) rotates counterclockwise, the aperture becomes larger.

Here, the reference position Ps of the diaphragm blade 4 is a position where the inner peripheral edge 43 of the diaphragm blade 4 constituting the diaphragm opening coincides with the fixed diaphragm opening 32 of the cam member 3 as shown in FIG. It ’s a position to open the aperture.

Further, the initial position P0 of the diaphragm blade 4 is a position in a direction in which the aperture diameter is further increased from the reference position Ps, and the diaphragm can be surely opened even if there is an assembly error in the components constituting the diaphragm device 220. This is the retracted position of the aperture blade 4.

On the other hand, the narrowing position Pf of the diaphragm blade 4 refers to a position where the opening formed by the inner peripheral edges 43 of the nine diaphragm blades 4 has a smaller diameter than the fixed diaphragm opening 32 of the cam member 3.

  FIG. 5 is a front view of the main part showing the rotating member 2 according to the present embodiment, and is a front view showing the positional relationship between the initial position P0, the reference position Ps, the narrowing position Pf, and the rotating member 2 (light shielding plate 23). is there.

For example, when the power source of the camera C is OFF, the rotating member 2 stops at the initial position P0, and the rotating member remains at the initial position P0 until the actual aperture control is performed by turning on the power source and starting photographing. stand by.

When the aperture control is started, a pulse signal based on the initial position P0 is output from the lens control unit 250 to the stepping motor 5, and the rotating member 2 rotates by an amount of movement corresponding to the pulse signal. A diaphragm aperture corresponding to the amount of movement is formed by the inner peripheral edge 43 of the diaphragm blade 4. This position is the narrowing position Pf. For example, the movement amount between the initial position P0 and the reference position Ps is 3 pulses, and the movement amount between the reference position Ps and the first narrowing down is 12 pulses.

When the photographing is completed, the rotating member 2 rotates in the reverse direction toward the initial position P0, passes through the reference position Ps, and waits again at the initial position P0.

As shown in FIG. 5, in the photo interrupter 6, when the rotary member 2 rotates from the narrowed position Pf toward the initial position P 0, the front end of the light shielding plate 23 in the traveling direction transmits the detection light of the photo interrupter 6. The positional relationship between the light shielding plate 23 and the photo interrupter 6 is determined so as to be shielded. The photo interrupter 6 detects the light shielding plate 23 by the photo interrupter 6 while the light shielding plate 23 moves in the direction of the initial position P0 after the front end of the light shielding plate 23 blocks the detection light of the photo interrupter 6. It is configured as follows.

For example, in the case of a two-phase type, the stepping motor 5 that rotates the rotary member 2 to drive the diaphragm blade 4 can be driven by a one-phase excitation method, a two-phase excitation method, or a 1-2 phase excitation method. It is not limited to these. Further, the invention is not limited to the two-phase type, and may be a three-phase type. When the drive pulse from the lens control unit 250 is input to the stepping motor 5, the rotor of the stepping motor 5 rotates by the input drive pulse.

FIG. 6A is a diagram showing a part of the stator 5 s and the rotor 5 r of the stepping motor 5 according to the present embodiment developed on a plane, and FIG. 6B is an excitation pattern input to the stepping motor 5. It is a figure which shows according to an excitation system.

As shown in FIG. 6A, a stator 5s made of an electromagnet in which a coil is wound through a gap is opposed to a rotor 5r made of a permanent magnet, and as shown in FIG. The currents supplied to the four excitation phases A, B, A , B of the coil of the stator 5s (A bar is indicated by A and B bar is indicated by B because “bar notation” cannot be used for the convenience of the electronic application format). By turning ON (+) / OFF (-), the rotor 5r rotates.

For example, in the one-phase excitation stepping motor shown in FIG. 4B, the rotor 5r is rotated by passing current sequentially through each of the four excitation phases A, B, A , and B , and in the two-phase excitation stepping motor, The rotor 5r is rotated by passing current sequentially through two adjacent excitation phases of the two excitation phases A, B, A and B. Further, in the 1-2 phase excitation stepping motor, the rotor 5r rotates by alternately performing 1 phase excitation and 2 phase excitation on the four excitation phases A, B, A and B.

The one-phase excitation stepping motor and the two-phase excitation stepping motor are driven by four excitation patterns 1 to 4 having different excitation states, and the 1-2 phase excitation stepping motor has eight excitation patterns having different excitation states. Drive by 1-8.

Next, an excitation pattern selection procedure at the initial position P0 of the stepping motor 5 according to the present embodiment will be described.

FIG. 7 is a diagram illustrating a driving method when selecting an excitation pattern of the stepping motor according to the present embodiment, and FIG. 8 is a graph and a diagram illustrating the relationship between the pulse signal and the movement angle with respect to the time of the diaphragm blade in the present embodiment. 9 is a flowchart showing a driving method when selecting an excitation pattern of the stepping motor according to the present embodiment.

When driving the diaphragm blade 4 to the desired narrowing position Pf, a pulse signal corresponding to the amount of movement to the target position is output to the stepping motor 5 with the diaphragm blade 4 being at the initial position P0. Therefore, if the aperture blade 4 is not accurately positioned at the initial position P0, the position accuracy of the aperture position Pf is lowered.

In this example, for example, in the manufacturing process of the aperture device 220 or the lens barrel 200, the excitation pattern of the stepping motor 5 corresponding to the initial position P0 of the aperture blade 4 is obtained and stored in the memory of the lens control unit 250. . When the diaphragm blade 4 is positioned at the initial position when using the camera C, the excitation blade 4 is output by outputting the excitation pattern of the stepping motor 5 stored in the memory of the lens control unit 250. Stop at the correct initial position P0.

Specifically, as shown in FIG. 7, when the diaphragm blade 4 is at an arbitrary narrowing position Pf1, a pulse signal is output to the stepping motor 5 at a time interval t1, and the diaphragm blade 4 is moved in the direction of the reference position Ps. Drive (step 101 in FIG. 9). Then, when the light shielding plate 23 is detected by the photo interrupter 6, the stepping motor 5 is stopped (steps S102 to S103 in FIG. 9). This position is assumed to be Ps1. The pulse signal output interval time t1 is not particularly limited, and can be set to a short time interval such that the diaphragm blades 4 are driven while the camera C is in use. Note that this operation can be omitted when the aperture blade 4 has already stopped at the reference position Ps.

Here, when the diaphragm blade 4 is driven by outputting a pulse signal to the stepping motor 5 at a short time interval t1, a delay of the rotation mechanism such as the diaphragm blade 4 and the rotating member 2 with respect to the pulse signal is generated and detected by the photo interrupter 6. The location may not be accurate. FIG. 8A shows this state.

As shown in the figure, the rotation mechanism such as the diaphragm blade 4 reaches the position corresponding to the first pulse signal PL1 with respect to the first pulse signal PL1 output from the lens control unit 250 at the time interval t1. Before the second pulse signal is output, a second pulse signal is output. By repeating this, the diaphragm blade 4 is delayed by Δω with respect to the pulse signal. Since the delay error Δω is not constant depending on the acceleration component of the stepping motor 5, it is difficult to estimate the delay error Δω.

Even if the reference position Ps is detected in the state where the delay error of Δω is generated in this way, the detected position includes the delay error Δω. Therefore, in the present embodiment, this delay error Δω is eliminated by the following procedure.

That is, following the above-described steps, a predetermined amount of pulse signal is output at a time interval t1 to the stepping motor 5 with the aperture blade 4 stopped at the reference position Ps1, and the aperture blade 4 is driven in the direction of the aperture position Pf ( Step S104 in FIG. 9). The time interval t1 at this time can be set to a short time interval such that the diaphragm blades 4 are driven during use of the camera C, as in the case described above. Further, the amount of movement in the direction of the narrowing position Pf is not particularly limited as long as the amount of movement is separated from the reference position Ps. By this operation, the aperture blade 4 stops at the aperture position Pf2.

Next, in a state where the aperture blade 4 is stopped at the aperture position Pf2, a pulse signal is output to the stepping motor 5 at a time interval t2, and the aperture blade 4 is driven in the reference position Ps direction (step S105 in FIG. 9). Then, when the light shielding plate 23 is detected by the photo interrupter 6, the stepping motor 5 is stopped (steps S106 to S107 in FIG. 9). This position is defined as a reference position Ps2.

At this time, the time interval t2 at which the pulse signal is output is longer than the time interval t1, and the time interval at which the rotation mechanism including the diaphragm blades 4 can be driven by the amount of movement commanded by the pulse signal. FIG. 8B shows this state.

As shown in the figure, the diaphragm blade 4 is moved by the first pulse signal during the time t2 from the output of the first pulse signal PL1 to the output of the second pulse signal PL2. If it can move by the amount, the delay of the diaphragm blade 4 is eliminated. As a result, the position where the light shielding plate 23 shields the photo interrupter 6 and the reference position Ps coincide with each other with high accuracy.

Finally, a predetermined amount of pulse signal is output at a time interval t2 to the stepping motor 5 with the diaphragm blade 4 stopped at the reference position Ps2, and the diaphragm blade 4 is driven in the direction of the initial position P0 and stopped (FIG. 9). Step S108). Then, the excitation pattern for the excitation phase of the stepping motor 5 at the initial position P0 is stored (step S109 in FIG. 9). For example, in the case of the one-phase excitation stepping motor and the two-phase excitation stepping motor shown in FIG. 6B, the excitation pattern is any one of 1 to 4, and in the case of the 1-2 phase excitation stepping motor, the excitation pattern. The excitation pattern is any one of 1 to 8. This excitation pattern is stored in the memory of the lens control unit 250 or the like.

When the diaphragm device 220 is driven, for example, a pulse signal is output from the arbitrary diaphragm position Pf in the direction of the initial position P0 at the time interval t1, and when the light shielding plate 23 shields the photo interrupter 6, the position is set as the reference position. Recognize as Ps, and further output a predetermined amount of pulse signal from the reference position Ps to stop the diaphragm blade 4 at the initial position P0. However, since there may be a delay error Δω in this state, the excitation pattern stored in the lens controller 250 is finally read and output to the stepping motor 5.

Thereby, the stop position of the rotary member 2 of the aperture blade 4 can be prevented from shifting, and the aperture blade 4 can be positioned at the accurate initial position P0.

It is a block diagram which shows the digital camera which concerns on embodiment of this invention. It is an assembly perspective view showing an electric diaphragm device according to an embodiment of the present invention. FIG. 3 is an exploded perspective view of FIG. 2. It is a front view which shows the drive position of the aperture blade which concerns on embodiment of this invention. It is a principal part front view which shows the rotating member which concerns on embodiment of this invention. It is a figure which shows the excitation pattern of the stepping motor which concerns on embodiment of this invention. It is a figure which shows the drive method at the time of selecting the excitation state of the stepping motor which concerns on embodiment of this invention. It is a graph which shows the relationship of the movement angle with respect to the time of the pulse signal and aperture blade in the drive method shown in FIG. It is a flowchart which shows the drive method when selecting the excitation pattern of the stepping motor which concerns on embodiment of this invention.

Explanation of symbols

220 ... Electric diaphragm device 1 ... Fixed member 2 ... Rotating member 3 ... Cam member 4 ... Diaphragm blade 5 ... Stepping motor 6 ... Photo interrupter 23 ... Shading plate P0 ... Initial position Ps ... Reference position Pf ... Narrowing position

Claims (7)

A diaphragm blade that makes the size of the opening variable,
Driving means for driving the diaphragm blades between an initial position and a narrowing position that limits the size of the opening, taking a plurality of excitation states;
Control means for outputting a drive signal to the drive means and changing the excitation state;
And a storage means for storing an excitation state of the drive means at the initial position. In the electric throttle device according to claim 1,
Detecting means for detecting that the diaphragm blades are located at a reference position separated from the initial position by a predetermined drive amount between the initial position and the aperture position;
The control means drives the diaphragm blades for the predetermined drive amount from the reference position detected by the detection means toward the initial position, and then sets the drive means to an excitation state stored in the storage means. Electric throttle device. In the electric throttle device according to claim 1 or 2,
The electric diaphragm device characterized in that the driving means is a stepping motor. A lens barrel comprising the electric diaphragm device according to any one of claims 1 to 3. An imaging apparatus comprising the electric diaphragm device according to any one of claims 1 to 3. Electricity for driving the diaphragm blades between the narrowed position and the initial position by changing the excitation state of the drive means by outputting a drive signal at a predetermined first time interval to the drive means for driving the diaphragm blades. A driving method of the diaphragm device,
A first step of outputting the driving signal to the driving means at a second time interval longer than the first time interval, and driving the diaphragm blades from the narrowing position toward the initial position;
A second step of detecting that the aperture blade has reached a reference position set between the aperture position and the initial position;
By outputting a driving signal corresponding to the interval between the reference position and the initial position to the driving means at the second time interval from the time when the diaphragm blade reaches the reference position, the diaphragm blades are moved to the initial position. A third step of stopping at the position;
And a fourth step of storing an excitation state of the driving means when stopped at the initial position as an excitation state corresponding to the initial position. In the driving method of the electric diaphragm device according to claim 6,
Prior to the first step,
Driving the diaphragm blades toward the reference position by outputting the drive signal to the drive means at the first time interval;
After the diaphragm blades reach the reference position, the diaphragm blades are driven from the reference position to the narrowing position by outputting the drive signal at the first time interval to the driving means. A driving method of the electric diaphragm device.

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