JP2016090742A - Shutter device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shutter device that can further shorten a shutter release time lag.SOLUTION: A shutter device comprises: a first light shield member that has a linear first end of a length corresponding to a width of an aperture, and shields a part of a light flux passing through the aperture upon moving the first end thereof along a prescribed movement direction from a first position out of the aperture; a second light shield member that has a linear second end of the length corresponding to the width of the aperture, moves the second end thereof along a movement direction from a second position on a side of the aperture further than the first position out of the aperture, and shields the light flux passing through the aperture; and a control unit that controls an electric power to be supplied to a first drive unit driving the first light shield member by a prescribed electric power, and a second drive unit driving the second light shield member thereby. The control unit makes the electric power to be supplied to the first drive unit upon starting a movement of the first light shield member smaller than the electric power supplied to the first drive unit when the first light shield member moves the aperture.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a shutter device and an imaging device.

  A so-called normally open type shutter device having a front curtain light shielding blade and a rear curtain light shielding blade is known. In an electronic camera equipped with this shutter device, in order to display a preview image in a shooting preparation state before performing the main exposure, the front curtain is shielded from the photographing opening of the shutter device to one side along the moving direction of each light shielding blade. The blade is retracted, and the rear curtain light-shielding blade is retracted on the other side (see, for example, Patent Document 1).

JP 2008-164804 A

In the electronic camera provided with the shutter device described in the above-mentioned patent document, the front curtain light-shielding blade that has been retracted from the photographing opening to one side is moved toward the other side before the main exposure starts to shield the photographing opening. Then, the reset operation of the image sensor is performed. Thereafter, the image capturing element is exposed by moving the front curtain light shielding blade and the rear curtain light shielding blade toward one side with a predetermined time difference. Therefore, the release time lag becomes longer.
However, a specific configuration of the shutter device that can further reduce the release time lag has not been proposed.

The shutter device has a substrate having a rectangular opening and a linear first end having a length corresponding to the width of the opening, and the first end is moved from the first position outside the opening of the substrate by a predetermined amount. A first light-shielding member that shields a part of the light flux passing through the opening when moving along the direction, and a linear second end having a length corresponding to the width of the opening, and the second end Is moved along the moving direction from the second position on the opening side of the first position outside the opening of the substrate, and the first light shielding member is driven with a predetermined power by shielding the light beam passing through the opening. A first driving unit, a second driving unit that drives the second light shielding member, and a control unit that controls electric power supplied to the first driving unit, and the control unit starts to move the first light shielding member. The first power supplied to the first drive unit during the first drive when the first light shielding member is moving through the opening Smaller than the second electric power supplied to.
An imaging device includes the shutter device described above and an imaging element that receives a light beam from a subject via the shutter device.

The principal part block diagram of the digital camera by embodiment. The block diagram which shows the structure of the control system of the digital camera by embodiment Plan view of shutter device according to embodiment The figure which shows typically the relationship between the distance which each slit formation edge moves, and an opening, when a front curtain and a rear curtain move from a storing position The diagram which shows the relationship between the electric power supplied to the actuator for front curtains and the actuator for rear curtains in 1st Embodiment, and time The figure which shows the relationship between the moving speed of the front curtain and rear curtain, and the time after starting supply of electric power in 1st Embodiment The diagram which shows the relationship between the electric power supplied to the actuator for front curtains in the modification (1) of 1st Embodiment, and time. The figure which shows typically the waveform of the electric power supplied to the actuator for front curtains in a modification A diagram showing a relationship between electric power supplied to the front curtain actuator and the rear curtain actuator and time in the second embodiment The figure which shows the relationship between the moving speed of the front curtain and rear curtain, and the time after starting supply of electric power in 2nd Embodiment The diagram which shows the relationship between the electric power supplied to the actuator for trailing curtains in the modification (1) of 2nd Embodiment, and time.

-First embodiment-
An imaging apparatus including a shutter device according to an embodiment will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a main part of a digital camera 1 that is an imaging apparatus according to the first embodiment, and FIG. 2 is a block diagram illustrating a configuration of a control system of the digital camera 1. As shown in FIG. 1, the digital camera 1 is a so-called mirrorless camera including a camera body 20 and a lens barrel 10 that can be attached to and detached from the camera body 20 via a lens mount 9. The digital camera 1 may be a single lens reflex camera instead of a mirrorless camera.

  The lens barrel 10 includes an imaging optical system 11 and a diaphragm 12. The imaging optical system 11 is an optical system for forming a subject image on a predetermined imaging surface, and is composed of a plurality of lenses including a focus adjustment lens. The focus adjustment lens moves forward and backward in the direction of the optical axis L by the operation of a lens driving motor (not shown). In FIG. 1, for convenience of illustration, the imaging optical system 11 is schematically shown as a single lens. The diaphragm 12 limits a light beam passing through the imaging optical system 11, that is, an incident light amount.

  Inside the camera body 20, a shutter device 21, an image sensor 22, and a control device 26 are provided. On the back surface of the camera body 20, a back monitor 30 constituted by a display device such as a liquid crystal display is provided. The camera body 20 is provided with an operation unit 40.

  The image pickup device 22 is an image pickup device such as a CMOS having a number of pixels arranged in a matrix, and is arranged so that the image pickup surface is positioned on the image formation surface of the image formation optical system 11. The imaging element 22 captures a subject image formed on the imaging surface by the imaging optical system 11 via the shutter device 21, and outputs an imaging signal to the control device 26. Although not shown in FIG. 1, various optical filters such as an infrared cut filter are provided on the imaging surface of the imaging element 22. A plurality of pixels constituting the image sensor 22 are two-dimensionally arranged in a pixel row direction (X-axis direction in FIG. 3 described later) and a pixel column direction orthogonal to the pixel row direction (Y-axis direction in FIG. 3 described later). The pixel reset and the readout of the imaging signal are performed at different timings for each pixel row at different positions in the pixel column direction.

  The shutter device 21 is provided on the front surface (subject side) of the image sensor 22. By driving the front curtain actuator 270 and the rear curtain actuator 271 (see FIG. 2) according to a drive signal from a power control unit 261 (see FIG. 2) of the control device 26 to be described later, the subject is directed toward the image sensor 22. This is a so-called focal plane shutter that shields incident light flux. The details of the shutter device 21 will be described later.

The control device 26 is composed of a microprocessor and its peripheral circuits and the like, and by reading and executing a control program stored in advance in a storage medium (not shown) (for example, a flash memory), each part of the digital camera 1 is controlled. Control. The control device 26 performs various image processing on the imaging signal output from the imaging element 22 to generate image data of the subject image, and generates the image data on a portable storage medium (not shown) (for example, a memory card). Record image data. The control device 26 controls the operations of the shutter device 21 and the image sensor 22 as will be described in detail later. The control device 26 includes a power control unit 261 (see FIG. 2) for controlling the operation of the shutter device 21 as a function.
Note that the control device 26 may be configured by an electronic circuit having a function equivalent to that of the control program.

  The operation unit 40 includes various switches provided corresponding to various operation members operated by the user, and outputs an operation signal corresponding to the operation of the operation member to the control device 26. The operation member determines, for example, a release button, a menu button for displaying a menu screen on the rear monitor 30, a cross key operated when selecting and operating various settings, a setting selected by the cross key, and the like. And a mode switching button for switching the operation of the digital camera 1 between the shooting mode and the playback mode.

Details of the shutter device 21 according to the embodiment will be described below.
FIG. 3 is a plan view of the shutter device 21. FIG. 3A shows a state before the start of shooting is instructed by the user operating the release button, that is, before the movement of the front curtain 211 is started. FIG. 3B shows a state where the movement of the front curtain 211 is completed. For convenience of explanation, a coordinate system consisting of an X axis and a Y axis is set as shown. The shutter device 21 includes a substrate 210, a front curtain 211, a rear curtain 212, a front curtain drive member 213, a rear curtain drive member 214, a front curtain actuator 270 (see FIG. 2), and a rear curtain actuator 271 ( 2). In FIG. 3, the front curtain actuator 270 and the rear curtain actuator 271 are omitted for the sake of illustration.

  The substrate 210 is fixed inside the camera body 20 and has an opening 215 for exposing the image sensor 22 with a subject light beam. The opening 215 is formed in a rectangular shape surrounded by two sides extending along the X axis and two sides extending along the Y axis. In the following description, it is assumed that the Y-axis side of the opening 215 is the upper end 215U, the Y-axis + side is the lower end 215B, and the length in the Y-axis direction between the upper end 215U and the lower end 215B is L0.

  The front curtain 211 is composed of a single blade, and is formed in, for example, a polygonal shape having sides (211U) extending along the X axis. An upper end 211U that is a side extending along the X axis on the Y axis minus side of the front curtain 211 has a length at least equal to or longer than the length of the opening 215 in the X axis direction. That is, the upper end 211U of the front curtain 211 has a length corresponding to the width of the opening 215 in the longitudinal direction. The length along the Y-axis direction (the movement direction of the shutter blades of the front curtain 211 and the rear curtain 212) between the upper end 211U and the lower end 211B that extends along the X axis on the Y axis + side of the front curtain 211 The length (light shielding width) L1 is shorter (smaller) than the length L0 of the opening 215 along the Y-axis direction. Therefore, the front curtain 211 has a structure that can cover only a part of the opening 215. That is, the front curtain 211 has a structure in which the light shielding range in the moving direction is shorter than the length of the opening 215 in the moving direction.

  The front curtain 211 that does not cover the entire opening 215 moves (runs) along the Y-axis direction by a front curtain drive member 213 described later, with the upper end 211U being parallel to the upper end 215U and the lower end 215B of the opening 215. That is, the upper end 211U of the front curtain 211 is a slit forming end at the time of slit exposure. As described above, since the pixel rows of the image sensor 22 extend along the X-axis direction, the pixel reset direction and the moving direction of the front curtain 211 are orthogonal to each other. The front curtain 211 is set so as to move in the Y axis + direction at the moving speed v1. This moving speed v1 has a characteristic that it is slow at the start of the movement of the front curtain 211 and gradually increases with acceleration.

The length L1 of the front curtain 211 in the Y-axis direction is determined so that the subject luminous flux is not irradiated to at least the pixel row of the image sensor 22 that is undergoing pixel reset. By matching the moving speed v1 of the front curtain 211 with the pixel reset speed based on the time required for the pixel reset of the image sensor 22 for the entire pixel row (usually can be arbitrarily set), the minimum design length of the length L1 is achieved. Can be the pixel pitch. However, in actual driving of the front curtain 211, it is difficult to completely match the moving speed v1 of the front curtain 211 with the pixel reset speed. Since other error factors are included, the length L1 of the front curtain 211 in the Y-axis direction is determined so as to satisfy the following expression (1).
L0> L1 ≧ ΔL11 (1)
Note that ΔL11 is a constant, a margin for deformation during movement due to manufacturing errors and material strength of the front curtain 211, a margin for preventing the influence of light that wraps around the end of the front curtain 211 in the Y-axis direction, and pixel reset The margin for the synchronization error between the speed and the moving speed v1 of the front curtain 211 is determined by experiments or the like.
In the present embodiment, the front curtain 211 is described as moving on the front surface (subject side) of the opening 215. However, the front curtain 211 also moves on the back surface of the opening 215 (imaging element 22 side). It is included in one aspect. Further, the front curtain 211 is not limited to the one configured with a single blade, and may be configured so as not to cover the entire opening 215 with a plurality of blades.

  The rear curtain 212 is constituted by a plurality of blades, and each blade is formed in, for example, two sides extending along the X axis and a rectangular shape extending along the Y axis. In the following description, the side extending along the X axis on the Y axis + side of the blade provided most on the Y axis + side among the plurality of blades constituting the rear curtain 212 is the lower end of the rear curtain 212. Called 212B. The lower end 212B of the rear curtain 212 has a length that is at least equal to or greater than the length of the opening 215 in the X-axis direction. That is, the lower end 212 </ b> B of the rear curtain 212 has a length corresponding to the width in the longitudinal direction of the opening 215.

  The rear curtain 212 moves (runs) along the Y-axis direction by a rear curtain driving member 214 described later. When the rear curtain 212 moves (runs) along the Y-axis direction and all the blades are deployed, the rear curtain 212 blocks the light beam incident from the subject on the entire area of the opening 215. The lower end 212B of the rear curtain 212 moves (runs) along the Y-axis direction in a state parallel to the upper end 215U and the lower end 215B of the opening 215. Therefore, at the time of exposure, the upper end 211U of the front curtain 211 and the lower end 212B of the rear curtain 212 move along the Y-axis direction in a state of being parallel to each other. That is, the lower end 212B of the rear curtain 212 is a slit forming end at the time of slit exposure. As described above, since the pixel rows of the image sensor 22 extend along the X-axis direction, the readout direction of the imaging signal and the moving direction of the trailing curtain 212 are orthogonal to each other. The rear curtain 212 is set to move in the Y axis + direction at the moving speed v2. This moving speed v2 has a characteristic that it is slow when the trailing curtain 212 starts to move, and gradually increases with acceleration.

In the present embodiment, the rear curtain 212 is described as moving on the front surface (subject side) of the opening 215. However, the rear curtain 212 also moves on the rear surface (image sensor 22 side) of the opening 215. Included in embodiments.
Further, in the present embodiment, the rear curtain 212 is not limited to the one that shields the entire area of the opening 215. Similarly to the front curtain 211, a part of the opening 215 may be shielded from light. In this case, the rear curtain 212 may be configured by a single blade or may be configured not to cover the entire opening 215 with a plurality of blades.

  The front curtain drive member 213 includes a first front curtain drive arm 213a, a second front curtain drive arm 213b, shafts 213c and 213d, and connecting pins 213e and 213f. The front curtain 211 is caulked and fixed to the X axis-side ends of the first front curtain drive arm 213a and the second front curtain drive arm 213b by connecting pins 213e and 213f. Ends on the X axis + side of the first front curtain drive arm 213a and the second front curtain drive arm 213b are pivotally supported on the substrate 210 by shafts 213c and 213d provided on the surface of the substrate 210.

The first front curtain drive arm 213a and the second front curtain drive arm 213b are connected to the front curtain actuator 270. The front curtain actuator 270 rotates the first front curtain drive arm 213a and the second front curtain drive arm 213b around the axes 213c and 213d on surfaces parallel to the XY plane, respectively. The front curtain actuator 270 is configured by an electric motor or the like. The front curtain actuator 270 is driven by receiving a drive signal from the power control unit 261 of the control device 26, that is, power supply. When the first front curtain drive arm 213a and the second front curtain drive arm 213b are rotationally driven as described above, the front curtain 211 moves along the Y-axis direction.
Note that the front curtain 211 is configured to remain at the storage position 220 in FIG. 3 even when power is not supplied to the front curtain actuator 270 from the power control unit 261.

  The rear curtain drive member 214 includes a first rear curtain drive arm 214a, a second rear curtain drive arm 214b, shafts 214c and 214d, and connecting pins 214e and 214f (see FIG. 3B). A rear curtain 212 is pivotally fixed to end portions on the X-axis side of the first rear curtain drive arm 214a and the second rear curtain drive arm 214b by connecting pins 214e and 214f. Ends on the X axis + side of the first rear curtain drive arm 214a and the second rear curtain drive arm 214b are pivotally supported on the substrate 210 by shafts 214c and 214d provided on the surface of the substrate 210.

The first rear curtain drive arm 214 a and the second rear curtain drive arm 214 b are connected to the rear curtain actuator 271. The rear-curtain actuator 271 rotates and drives the first rear-curtain drive arm 214a and the second rear-curtain drive arm 214b about the shafts 214c and 214d in planes parallel to the XY plane, respectively. The rear curtain actuator 271 is configured by an electric motor or the like. The front curtain actuator 271 is driven by receiving a drive signal from the power control unit 261 of the control device 26, that is, power supply. As a result, the first rear curtain drive arm 214a and the second rear curtain drive arm 214b are rotationally driven as described above, so that the rear curtain 212 moves along the Y-axis direction.
Note that the rear curtain 212 is configured to remain at the storage position 220 in FIG. 3 even when power is not supplied from the power control unit 261 to the rear curtain actuator 271.

Next, the operation of the shutter device 21 will be described with reference to FIG.
Until the release button is operated by the user and shooting is instructed, the front curtain 211 is retained and stored in the storage position 220 as described above (see FIG. 3A). The storage position 220 is outside the area of the opening 215 formed in the substrate 210, that is, the area on the Y axis minus side from the upper end 215U. As described above, the rear curtain 212 is retained and stored in the storage position 220 on the Y axis minus side from the upper end 215U of the opening 215. That is, when the front curtain 211 and the rear curtain 212 are stored in the storage position 220, the opening 215 is not shielded by the front curtain 211 and the rear curtain 213. In this state, a so-called live view display is performed in which the imaging signal is repeatedly read from the imaging element 22 and an image (preview image) corresponding to the imaging signal is displayed on the rear monitor 30.

  When the user operates the release button, supply of power for moving the front curtain 211 to the power control unit 261 and the front curtain actuator 270 is started. When electric power is supplied, the first front curtain drive arm 213a and the second front curtain drive arm 213b are driven to rotate in a plane parallel to the XY plane around the shafts 213c and 213d, respectively. Therefore, the front curtain 211 moves in the Y axis + direction from the storage position 220. In the front curtain 211, the upper end 211U moves to the Y axis + side from the lower end 215B of the opening 215 (see FIG. 3B). This drive power is power required to drive the front curtain drive member 213 so that the front curtain 211 moves through the opening 215 at the moving speed v1. The power control unit 261 has a large difference in moving speed when the slit forming end (upper end 211U) of the front curtain 211 and the slit forming end (lower end 212B) of the rear curtain 212 move in the same position in the Y-axis direction. The supply of power to the front curtain actuator 270 is controlled so that this can be prevented and the occurrence of uneven exposure can be suppressed. Details of the control of power supply to the front curtain actuator 270 will be described later.

  When the time corresponding to the exposure time elapses after the front curtain 211 starts moving, the power control unit 261 supplies power for moving the rear curtain 212 to the rear curtain actuator 271. When electric power is supplied, the first rear curtain drive arm 214a and the second rear curtain drive arm 214b are driven to rotate in a plane parallel to the XY plane around the axes 214c and 214d, respectively. Therefore, the trailing curtain 212 moves from the storage position 220 in the Y axis + direction. The rear curtain 212 moves to a position (movement end position) where the lower end 212B of the rear curtain 212 is on the + side in the Y-axis direction by a predetermined distance from the lower end 215B of the opening 215. When reading of the imaging signal from the image sensor 22 is completed, the control device 26 drives the front curtain actuator 270 and the rear curtain actuator 271 to move the front curtain 211 and the rear curtain 212 in the Y-axis direction to store them. By storing at the position 220, the exposure operation is terminated.

  In the present embodiment, as described above, the front curtain 211 and the rear curtain 212 are stored in the same storage position 220 until the start of exposure. For this reason, it is not necessary to move the front curtain 211 to the charge position with the start of exposure, as compared with the case where the front curtain 211 and the rear curtain 212 are stored in positions facing each other across the opening 215. Therefore, the release time lag can be shortened compared to the conventional case. However, as will be described later, the distance when the upper end 211U that is the slit forming end of the front curtain 211 moves to the upper end 215U of the opening 215 (the running range of the front curtain 211) and the lower end that is the slit forming end of the rear curtain 212 The distance at which 212B moves to the upper end 215U of the opening 215 (the run-up range of the rear curtain 212) is greatly different. In the present embodiment, power supply to the front curtain actuator 270 is controlled so that there is no significant difference in the movement characteristics between the front curtain 211 and the rear curtain 212 during exposure.

  Hereinafter, control of power supplied to the front curtain actuator 270 and the rear curtain actuator 271 by the power control unit 261 will be described. FIG. 4A schematically shows the relationship between the opening 215 and the distance to which the slit forming end (that is, the upper end 211U) moves when the front curtain 211 moves from the storage position 220. FIG. FIG. 4B schematically shows the relationship between the distance that the slit forming end (that is, the lower end 212 </ b> B) moves and the opening 215 when the rear curtain 212 moves from the storage position 220. In FIG. 4B, for convenience of illustration, only a blade having a slit forming end among the plurality of blades constituting the rear curtain 212 is shown.

  As shown in FIG. 4A, when the front curtain 211 is stored in the storage position 220, the position in the Y-axis direction of the upper end 211U that is the slit forming end of the front curtain 211 is Y0. The position of the upper end 215U of the opening 215 in the Y-axis direction is Y2. The position of the lower end 215B of the opening 215 in the Y-axis direction is Y3. In the following description, it is assumed that the exposure start position coincides with the upper end 215U of the opening 215 for convenience of explanation. When the exposure starts, the front curtain 211 accelerates while the upper end 211U of the front curtain 211 moves from the position Y0 to the position Y2. At the time of exposure, the upper end 211U of the front curtain 211 moves while accelerating from the position Y2 to the position Y3. In the present specification, in the following description, the range from the position Y0 to Y2 is referred to as the run-up range R1 of the front curtain 211.

  As shown in FIG. 4B, when the rear curtain 212 is stored in the storage position 220, the position in the Y-axis direction of the lower end 212B, which is the slit forming end of the rear curtain 212, is Y1 (<Y2). That is, the lower end 212 </ b> B that is the slit forming end of the rear curtain 212 is positioned closer to the opening 215 than the upper end 211 </ b> U that is the slit forming end of the front curtain 211. At the start of exposure, the rear curtain 212 accelerates while the lower end 212B of the rear curtain 212 moves from the position Y1 to the position Y2. At the time of exposure, the lower end 212B of the trailing curtain 212 moves while accelerating from the position Y2 to the position Y3. In the present specification, in the following description, the range from the positions Y1 to Y2 is referred to as the run-up range R2 of the trailing curtain 212. Since the lower end 212B of the rear curtain 212 is located closer to the opening 215 than the upper end 211U of the front curtain 211, the running range R2 of the rear curtain 212 is smaller than the running range R1 of the front curtain 211.

  FIG. 5 is a diagram showing the relationship between the power supplied to the front curtain actuator 270 and the rear curtain actuator 271 and time. While moving from the start of the movement of the front curtain 211 in the run-up range R1, the power control unit 261 supplies power to the front curtain actuator 270 until the power value P1 is reached. This power value P1 is the power required for the front curtain 211 to move through the opening 215 at the moving speed v1. As shown in FIG. 5, the power control unit 261 starts supplying power to the front curtain actuator 270 at time t0, and supplies power so as to reach the power value P1 at time t1. The power control unit 261 supplies power to the front curtain actuator 270 at an increase rate ΔP1 per unit time. After time t1, when the front curtain 211 travels through the opening 215, the power control unit 261 supplies power to the front curtain actuator 270 at a constant power value P1. In other words, the power control unit 261 supplies the power supplied to the front curtain actuator 270 while the front curtain 211 is moving through the opening range 215 while the front curtain 211 is moving through the opening 215 when the front curtain 211 starts moving. It is made smaller than the electric power supplied to 270. In other words, the power control unit 261 supplies the power per unit time supplied to the front curtain actuator 270 when the front curtain 211 starts moving, and the front curtain actuator 270 when the front curtain 211 moves through the opening 215. Less than the power per unit time supplied to For this reason, the electric power supplied to the front curtain actuator 270 by the time t0 to t1 when the front curtain 211 moves in the run-up range R1 is equal to the time from the time t1 to the time t0 to t1 after the time t1 (for example, It becomes smaller than the power supplied at times t1 to t1 ′) in FIG.

  When the rear curtain 212 starts to move, the power control unit 261 supplies the rear curtain actuator 271 with the power of the power value P2. The electric power P2 is electric power required to reach the moving speed v2 when the trailing curtain 211 moves through the opening 215. As shown in FIG. 5, the power control unit 261 supplies the power of the power value P2 to the trailing curtain actuator 271 at time t2 when a time corresponding to the exposure time has elapsed. That is, as shown in the figure, the rear curtain actuator 271 is supplied with electric power so as to form a rectangular waveform.

  As described above, the power control unit 261 requires time for the power supplied to the front curtain actuator 270 to reach the power value P1 until the power supplied to the rear curtain actuator 271 reaches the power value P2. Control to be longer than time. In other words, the power control unit 261 does not supply power to the front curtain actuator 270 so as to form a rectangular waveform unlike the power supply to the rear curtain actuator 271. For this reason, compared with the case where electric power that forms a rectangular waveform is supplied, the rate of increase in the number of revolutions of the electric motor constituting the front curtain actuator 270 is small. Since the rate of increase in the number of revolutions of the electric motor is small, the rate of increase when the first front curtain drive arm 213a and the second front curtain drive arm 213b are rotationally driven is also reduced. As a result, acceleration of the leading curtain 211 that is moving in the approach range R1 is suppressed.

  FIG. 6 shows the relationship between the position of the front curtain 211 and the rear curtain 212 in the Y-axis direction and the time when the power supply is controlled as described above. In FIG. 6, the vertical axis indicates the position in the Y-axis direction, and the horizontal axis indicates time. K1 indicated by a solid line indicates the position of the front curtain 211 when receiving power supply according to the present embodiment, and K2 indicated by a broken line indicates the position of the rear curtain 212.

  As shown in FIG. 6, the front curtain 211 when receiving power supply according to the present embodiment indicated by K <b> 1 moves the upper end 215 </ b> U (position Y <b> 2) of the opening 215 at time t <b> 3 and the opening curtain 215 at time t <b> 5. The lower end 215B (position Y3) is moved. As shown by K2, the rear curtain 212 moves the upper end 215U (position Y2) of the opening 215 at time t4, and moves the lower end 215B (position Y3) of the opening 215 at time t6. Therefore, as illustrated, the exposure time at the upper end 215U of the opening 215 is (t4-t3), and the exposure time at the lower end 215B is (t6-t5).

  As described above, since the acceleration when the front curtain 211 moves in the run-up range R1 is suppressed, an increase in speed when the front curtain 211 moves from the upper end 215U to the lower end 215B of the opening 215 is suppressed. . On the other hand, since the electric power having the electric power value P2 is supplied to the rear curtain actuator 271 at time t2, the acceleration when the rear curtain 212 is moving the distance of the run-up range R2 is not suppressed. Therefore, an increase in speed when the rear curtain 212 moves from the upper end 215U of the opening 215 to the lower end 215B is not suppressed. However, since the run-up range R2 of the rear curtain 212 is smaller than the run-up range R1 of the front curtain 211, the moving speed of the rear curtain 212 is not extremely accelerated.

As a result, the difference between the exposure time (t 4 -t 3) at the upper end 215 U of the opening 215 and the exposure time (t 6 -t 5) at the lower end 215 B becomes smaller than the comparative example described later. Therefore, it is possible to suppress the occurrence of exposure unevenness (vertical unevenness) in the vertical direction of the image due to the difference in exposure time depending on the position in the Y-axis direction.
In order to change the shutter speed, the traveling timing of the front curtain 211 and the rear curtain 212 may be changed as is well known, and this embodiment can be applied in the same manner as the conventional shutter.

(Comparative example)
As a comparative example, a case where the power of the power value P1 is received so that the front curtain actuator 270 forms a rectangular waveform at time t0 will be described. The position of the front curtain 211 in the case of the comparative example is indicated by K3 represented by a one-dot chain line in FIG. In this case, as in the case of the rear curtain 212 described above, acceleration when the front curtain is moving in the run-up range R1 is not suppressed, and the front curtain moves from the upper end 215U of the opening 215 to the lower end 215B. The increase in speed is not suppressed. The running range R1 of the leading curtain 211 is longer than the running range R2 of the trailing curtain 212. Therefore, the moving speed of the front curtain 211 in the comparative example is higher than that in the embodiment, and the speed of the front curtain 211 increases when the front curtain 211 moves from the upper end 215U to the lower end 215B of the opening 215. This is larger than the increase in the speed of the trailing curtain 212. As a result, as indicated by K3, the front curtain moves the upper end 215U of the opening 215 at time t31 (<t3), and moves the lower end 215B of the opening 215 at time t51 (<t5). Therefore, as illustrated, in the case of the comparative example, the exposure time at the upper end 215U of the opening 215 is (t4-t31), and the exposure time at the lower end 215B is (t6-t51). That is, the difference between the exposure time (t4-t31) at the upper end 215U of the opening 215 and the exposure time (t6-t51) at the lower end 215B becomes large, causing uneven exposure in the vertical direction of the image and lowering the image quality. become.

According to the first embodiment described above, the following operational effects can be obtained.
(1) The shutter device 21 is configured so that both the front curtain 211 and the rear curtain 212 are retracted to the Y-axis-side storage position 220 in the shooting preparation state before performing the main exposure. At the time of the main exposure, while moving the front curtain 211 toward the Y axis + side, the range of light shielding by the front curtain 211 of the image sensor 22 is reset, and the rear curtain 212 is shifted from the front curtain 211 by a predetermined time difference. Is moved toward the Y axis + side to complete the exposure of the image sensor 22.

  If the shutter device 21 is configured so that both the front curtain 211 and the rear curtain 212 are retracted to the storage position 220, the run-up range R2 of the front curtain 211 is larger than the run-up range R1 of the rear curtain 212. Therefore, the speed of movement of the front curtain 211 is larger than that of the rear curtain 212, and the speed difference between the front curtain 211 and the rear curtain 212 increases for each position along the Y-axis direction of the opening 215. May cause uneven exposure.

  Therefore, in the present embodiment, the power control unit 261 first supplies the power supplied to the front curtain actuator 270 when the movement of the front curtain 211 starts, while the front curtain 211 moves through the opening 215. The electric power supplied to the curtain actuator 270 is made smaller. In the front curtain 211 and the rear curtain 212 that start moving from the same storage position 220 at the start of exposure, the moving speed with respect to the front curtain 211 that moves in a larger run-up range R1 than the run-up range R2 of the rear curtain 212 The increase of is suppressed. An increase in the moving speed of the front curtain 211 when the front curtain 211 moves from the upper end 215U to the lower end 215B of the opening 215 is also suppressed. As a result, the difference between the exposure time at the upper end 215U of the opening 215 and the exposure time at the lower end 215B is reduced, and the occurrence of uneven exposure in the vertical direction of the image can be suppressed to prevent deterioration in the image quality of the captured image.

Further, unlike the technique of accelerating the front curtain and the rear curtain until reaching a specific constant speed state before the start of exposure, each of the front curtain 211 and the rear curtain 212 moving in the approaching ranges R1 and R2 has a large electric power. Need not be supplied. Therefore, in a digital camera that performs many processes such as focus adjustment, camera shake correction, aperture drive, image sensor drive, and image processing during shooting, it is possible to suppress power supply required for the operation of the shutter device 21.
Also, when power is supplied by the above technique, particularly when the exposure time is short (high shutter speed), a state in which large power is instantaneously supplied to the front curtain and the rear curtain in the overlapping period. May occur. In this case, the electrical efficiency is deteriorated as compared with when power is consumed on average, and the life of the battery is reduced. On the other hand, in the present embodiment, it is possible to prevent the occurrence of a state in which a large amount of power is instantaneously supplied as described above, thereby suppressing deterioration in electrical efficiency and preventing a decrease in battery life. it can.

  Furthermore, it is not necessary to increase the running range R1 of the front curtain 211 and the running range R2 of the rear curtain 212 so that the front curtain 211 and the rear curtain 212, which are sufficiently accelerated, move through the opening 215. As a result, it is possible to prevent the blades constituting the front curtain 211 and the rear curtain 212 from increasing in size and mass, and the shutter device 21 from increasing in size.

(2) The power control unit 261 increases the power supplied to the front curtain actuator 270 at an increase rate ΔP1 per unit time after the front curtain 211 starts moving. Therefore, an increase in the moving speed of the front curtain 211 that is moving in the approaching range R1 can be suppressed as compared with the case where power is supplied so as to have a rectangular waveform.

The shutter device 21 of the first embodiment described above can be modified as follows.
(1) It is not limited to supplying power to the leading curtain actuator 270 at an increase rate ΔP1 per unit time. For example, the power control unit 261 may increase the power supplied to the front curtain actuator 270 in a stepwise manner from time t0 to time t1. In this case, for example, as shown in FIG. 7, the power of the power value P10 (<P1) is supplied to the front curtain actuator 270 at time t0. At time t10, the power of the power value P11 (P10 <P11 <P1) is supplied to the front curtain actuator 270. Then, at time t1, the power of the power value P1 is supplied to the front curtain actuator 270. As a result, as in FIG. 7, an increase in the speed of the leading curtain 211 in the approach range R1 is suppressed. Therefore, as in the case of the embodiment, the difference between the exposure time at the upper end 215U of the opening 215 and the exposure time at the lower end 215B is reduced, and the occurrence of uneven exposure (vertical unevenness) in the vertical direction of the image is suppressed. Can do.

(2) The waveform of the electric power supplied to the front curtain actuator 270 is not limited to the examples shown in FIGS. The electric power supplied to the front curtain actuator 270 when the movement of the front curtain 211 starts is controlled to be smaller than the electric power supplied to the front curtain actuator 270 when the front curtain 211 moves through the opening 215. Just do it. The power supplied to the front curtain actuator 270 by the time t0 to t1 is controlled to be smaller than the power supplied during the same time as the time from the time t0 to the time t1 after the time t1. FIG. 8 shows an example of a waveform of power supplied to the front curtain actuator 270. In FIG. 8A, electric power having a rectangular waveform is supplied to the front curtain actuator 270 in the range of time t0 to t10 (t0 <t10 <t1), and thereafter, electric power is supplied in the range of time t10 to t1. Interrupted. Then, after time t1, electric power having a constant electric power value P1 is supplied to the front curtain actuator 270 again.

In FIG. 8B, the power increases until reaching the peak power value Pp (> P1) at a predetermined increase rate in the range of time t0 to t10 (t0 <t10 <t1), and the power value P1 at time t1. Power is supplied to the front curtain actuator 270 so that the power decreases until After time t1, electric power having a constant electric power value P1 is supplied to the front curtain actuator 270. In FIG. 8C, electric power is supplied to the front curtain actuator 270 in the range of time t0 to t1, similarly to the case shown in FIG. 8B. After time t1, the power supplied to the front curtain actuator 270 increases from the power value P1 at a predetermined increase rate. In FIG. 8D, the electric power supplied to the leading curtain actuator 270 increases within a range of time t0 to t1 until the electric power value P1 is reached at a predetermined increase rate ΔP1. After time t1, the electric power supplied to the front curtain actuator 270 increases at a predetermined increase rate.
(3) The rear curtain actuator 271 may be mechanically driven instead of being electrically driven. In the case of mechanical driving, electric power may be replaced with mechanical driving force (or driving torque).

-Second Embodiment-
A second embodiment of the present invention will be described with reference to the drawings. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. The present embodiment is different from the first embodiment in that the power control unit supplies power to the rear curtain actuator in the same manner as the power supply to the front curtain actuator.

  FIG. 9 is a diagram showing the relationship between the power supplied to the front curtain actuator 270 and the rear curtain actuator 271 and time. The first curtain actuator 270 is supplied with electric power so as to increase to the electric power P1 at a time t1 'longer than t1 as compared with the case of the first embodiment. Therefore, for the front curtain 211, the moving section until the power P1 is reached is longer than that in the first embodiment. The power control unit 261 supplies power to the rear curtain actuator 271 until the power value P2 is reached while the rear curtain 212 is moving in the approach range R2 from the start of movement. This power value P2 is power required for the trailing blade 212 to move through the opening 215 at the moving speed v2. The power control unit 261 starts supplying power to the trailing curtain actuator 271 at time t2, and supplies power so as to reach the power value P2 at time t3. The power control unit 261 supplies power to the trailing curtain actuator 271 at an increase rate ΔP2 per unit time. After time t3, when the rear curtain 212 travels through the opening 215, the power control unit 261 supplies power to the rear curtain actuator 271 at a constant power value P2. That is, the power control unit 261 supplies the power supplied to the rear curtain actuator 271 while moving in the run-up range R2 when the rear curtain 212 starts moving, and the rear curtain actuator while the rear curtain 212 moves through the opening 215. The electric power supplied to 271 is made smaller. In other words, the power control unit 261 supplies the power per unit time supplied to the rear curtain actuator 271 when the rear curtain 212 starts moving, and the rear curtain actuator 271 when the rear curtain 212 moves through the opening 215. Less than the power per unit time supplied to For this reason, the electric power supplied to the rear curtain actuator 271 before the time t2 to t3 when the rear curtain 212 moves in the approach range R2 is the same as the time from the time t2 to the time t2 after the time t2 (see FIG. 9 is smaller than the power supplied at time t3 to t3 ′). That is, the power of the power value P2 is supplied to the rear curtain actuator 271 in a time shorter than the time of supplying the power of the power value P1 to the front curtain actuator 270.

  Even in this case, the power control unit 261 supplies the power to the trailing curtain actuator 271 in comparison with the time (t1-t0) required for the power supplied to the leading curtain actuator 270 to reach the power value P1. Control is performed so that the time (t3-t2) required for the electric power to reach the electric power value P2 is shortened. For this reason, also in the present embodiment, the rate of increase in the rotational speed of the electric motor constituting the front curtain actuator 270 is smaller than that of the rear curtain actuator 271.

  FIG. 10 shows the relationship between the positions of the front curtain 211 and the rear curtain 212 in the Y-axis direction and the time since the start of power supply when the power supply is controlled as described above. 10, as in FIG. 6, the vertical axis indicates the distance in the Y-axis direction, and the horizontal axis indicates time. K1 'indicated by a solid line indicates the position of the front curtain 211 when receiving power supply according to the present embodiment, and K2' indicated by a solid line indicates the position of the rear curtain 212 of the present embodiment. Further, K2 indicated by a broken line indicates the position of the trailing curtain 212 in the case of the first embodiment.

As shown in FIG. 10, the front curtain 211 indicated by K1 ′ moves the upper end 215U (position Y2) of the opening 215 at time t3 later than in the first embodiment, and the lower end 215B of the opening 215 at time t5. Move (position Y3). That is, since acceleration when the front curtain 211 is moving in the run-up range R1 is suppressed, an increase in speed when the front curtain 211 moves from the upper end 215U of the opening 215 to the lower end 215B is suppressed. By controlling the power supplied to the rear curtain actuator 271 as described above, the rear curtain 212 moves the upper end 215U of the opening 215 at time t41 and opens at time t61, as indicated by K2 ′. The lower end 215B of 215 is moved. Compared to the moving speed of the trailing curtain 212 of the first embodiment shown in K2, the trailing curtain 212 of the present embodiment is restrained from accelerating when moving in the run-up range R2. Increases the speed when moving from the upper end 215U of the opening 215 to the lower end 215B. As a result, as illustrated, the exposure time at the upper end 215U of the opening 215 is (t41-t3), while the exposure time at the lower end 215B of the opening 215 is (t61-t5), and the exposure time at the upper end 215U of the opening 215. The difference between (t41−t3) and the exposure time (t61−t5) at the lower end 215B can be suppressed small, and the occurrence of exposure unevenness can be suppressed.
The exposure time (t41-t3) at the upper end 215U of the opening 215 is longer than the exposure time (t4-t3) in the first embodiment, and the exposure time (t61-t5) at the lower end 215B of the opening 215. ) Is longer than the exposure time (t6-t5) in the case of the first embodiment, but as described above, the desired shutter speed is controlled by controlling the timing of the front curtain 211 and the rear curtain 212. can do.

According to the second embodiment described above, the following functions and effects can be obtained in addition to the functions and effects (1) to (2) obtained in the first embodiment.
(1) The power control unit 261 supplies power to the rear curtain actuator 271 when the rear curtain 212 starts moving, and supplies the power to the rear curtain actuator 271 when the rear curtain 212 moves through the opening 215. Make it smaller than the power you use. Therefore, an increase in the speed of the trailing curtain 212 can be suppressed in the same manner as the leading curtain 211 in the first embodiment.
In particular, when the power value P2 of the power supplied to the rear curtain actuator 271 is larger than the power value P1 of the power supplied to the front curtain actuator 270, by suppressing the increase in the speed of the front curtain 211, the front curtain There is a possibility that the speed difference for each position in the Y-axis direction between the second curtain 211 and the rear curtain 212 increases. In this embodiment, in such a case, by controlling the power supplied to the rear curtain 212, an increase in the speed of the rear curtain 212 is suppressed, and exposure between the upper end 215U and the lower end 215B of the opening 215 is performed. The occurrence of uneven exposure due to an increase in time difference can be suppressed.

(2) After the trailing curtain 212 starts moving, the power control unit 261 increases the power supplied to the trailing curtain actuator 212 to the power P2 at an increase rate ΔP2 per unit time. Therefore, an increase in the moving speed of the rear curtain 212 that is moving in the approaching range R2 can be suppressed as compared with the case where power is supplied so as to have a rectangular waveform.

(3) The power control unit 261 supplies the power of the power value P2 to the rear curtain actuator 271 in a time shorter than the time of supplying the power of the power value P1 to the front curtain actuator 270. Accordingly, the moving speed of the rear curtain 212 becomes excessively slow, and the moving speed of the front curtain 211 and the rear curtain 212 at the upper end 215U of the opening 215 and the moving speed of the front curtain 211 and the rear curtain 212 at the lower end 215B of the opening 215 Suppresses the difference from increasing. That is, it is possible to suppress an increase in the exposure time at the lower end 215B compared to the exposure time at the upper end 215U of the opening 215, and to suppress occurrence of exposure unevenness (vertical unevenness) in the vertical direction of the image.

The shutter device 21 according to the second embodiment described above can be modified as follows.
(1) Instead of the power supplied to the trailing curtain actuator 271 increasing at an increase rate ΔP2 per unit time, it may be increased stepwise from time t2 to time t3. In this case, for example, as shown in FIG. 11, the power of the power value P20 (<P2) is supplied to the trailing curtain actuator 271 at time t2. At time t20, the power of the power value P21 (P20 <P21 <P2) is supplied to the trailing curtain actuator 271. Then, at time t3, the power of the power value P2 is supplied to the trailing curtain actuator 271. In this case, power may be supplied to the front curtain actuator 270 so as to increase stepwise as shown in FIG. 11, or to increase at an increase rate ΔP1 as shown in FIG. Electric power may be supplied.

(2) The waveform of the power supplied to the front curtain actuator 270 or the rear curtain actuator 271 is not limited to the examples shown in FIGS. 9 and 11, and the power of the waveform shown in FIG. it can. In this case, the waveforms of the power supplied to the leading curtain actuator 270 and the trailing curtain actuator 271 do not have to match. For example, power is supplied to the front curtain actuator 270 with the waveform shown in FIG. 8A, and power is supplied to the rear curtain actuator 271 with the waveform shown in FIG. 8B. be able to. Even in such a case, the time until the power supplied to the rear curtain actuator 271 reaches the power value P2 is longer than the time until the power supplied to the front curtain actuator 270 reaches the power value P1. The supply of power is controlled so as to be shorter.

As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .
In the above-described embodiments and modifications, the power supplied to the front curtain actuator 270 or the rear curtain actuator 271 while the front curtain 211 is moving in the running range R1 and the rear curtain 212 is moving in the running range R2 is provided. The case of controlling has been described. However, the present invention is not limited to this example, and the electric power that is continuously supplied to a position where the front curtain 211 and the rear curtain 212 reach the opening 215 beyond the run-up ranges R1 and R2 may be controlled.

DESCRIPTION OF SYMBOLS 1 ... Digital camera, 21 ... Shutter apparatus, 22 ... Image sensor, 26 ... Control apparatus,
210 ... Substrate, 211 ... Front curtain, 212 ... Rear curtain, 213 ... Front curtain drive member,
214 ... rear curtain drive member, 215 ... opening, 261 ... power control unit,
270 ... Actuator for front curtain, 271 ... Actuator for rear curtain

Claims (6)

A substrate having a rectangular opening;
The linear first end portion having a length corresponding to the width of the opening is provided, and the opening is moved when the first end portion is moved along a predetermined movement direction from a first position outside the opening of the substrate. A first light shielding member for shielding a part of the light flux passing through
The linear second end having a length corresponding to the width of the opening is provided, and the second end is moved from the second position outside the opening of the substrate to the moving direction from the second position on the opening side. A second light-shielding member that travels along and shields the light beam passing through the opening;
A first drive unit that drives the first light shielding member with a predetermined power;
A second driving unit for driving the second light shielding member;
A control unit that controls electric power supplied to the first drive unit,
The control unit supplies the first power supplied to the first driving unit when starting the movement of the first light shielding member, and the first driving unit when the first light shielding member is moving through the opening. The shutter device is made smaller than the second power supplied to the. The shutter device according to claim 1,
The said control part is a shutter apparatus which increases the electric power supplied to the said 1st drive part by the predetermined | prescribed increase rate per unit time after a movement start of a said 1st light-shielding member. The shutter device according to claim 1 or 2,
The second driving unit drives the second light shielding member with a predetermined power,
The control unit supplies the third power supplied to the second driving unit when starting the movement of the second light shielding member, and the second driving unit when the second light shielding member is moving through the opening. Shutter device for lower than fourth power supplied to The shutter device according to claim 3.
The said control part is a shutter apparatus which supplies the said 3rd electric power in a time shorter than the time which supplies the said 1st electric power. The shutter device according to claim 3 or 4,
The said control part is a shutter apparatus which increases the electric power supplied to the said 2nd drive part by the predetermined | prescribed increase rate per unit time after the movement start of a said 2nd light-shielding member. The shutter device according to any one of claims 1 to 5,
An imaging device comprising: an imaging device that receives a light beam from a subject via the shutter device.

Images