JP4949698B2 - Light amount adjusting device and imaging device - Google Patents

Description

  The present invention relates to a light amount adjusting device and an imaging device used in optical equipment such as a digital still camera and a video camera.

  2. Description of the Related Art Conventionally, a light amount adjusting device such as an optical device used in a digital still camera, a video camera, or the like has been used in many cases using a so-called galvanometer as a driving source. In this diaphragm mechanism, the position of a rotor, which is a permanent magnet of a galvanometer, is detected using a Hall element, and the detection result is feedback-controlled to operate the rotor to a target position, thereby performing diaphragm control.

  Furthermore, a light amount adjustment device mounted on a digital still camera or the like that requires a shutter mechanism applies an excitation magnetic field generated by the permanent magnet and coil of the galvanometer from the aperture control position described above to rotate the rotor by repulsion and suction operations. The aperture control is performed to open and close the aperture shutter blades to perform the shutter operation.

  However, when the galvanometer is used as a drive source in the aperture mechanism as described above, a detection unit for detecting the position of the rotor is required, and a control unit for feedback controlling the output result of the position detection unit is required. Therefore, there is a problem that the drive circuit becomes large and the number of parts increases.

  Furthermore, when a galvanometer is used as a driving source, the speed is slow even when a shutter operation is performed, and it is not suitable for high-speed time adjustment.

  Therefore, a diaphragm mechanism using a stepping motor instead of a galvanometer as a drive source can be considered. In a diaphragm mechanism using a stepping motor, for example, as disclosed in Patent Document 1, a linear drive lever is press-fitted into a rotating shaft of a stepping motor, and a drive pin is provided on the drive lever. The drive pins are engaged through the long holes of the two aperture shutter blades. In such an aperture mechanism, the stepping motor is rotated to cause the two aperture shutter blades to go straight in opposite directions. The amount of light is adjusted by changing the size of the opening of the two aperture shutter blades according to their positional relationship, and the shutter operation is performed by rotating the stepping motor at high speed in the direction in which the blades close.

Further, the aperture / shutter mechanism using the stepping motor requires means for detecting the closed position (initial position) in order to guarantee the aperture diameter. For example, as in Patent Document 2, the initial position is controlled by aperture control. Some of them are provided with home position detecting means for detecting the above.
JP 2004-109531 A JP-A-6-59309

  In the light amount adjusting apparatus using the above-described driving unit, for example, home position detecting means for detecting whether or not the position of the aperture is in the initial position and whether or not the stepping motor is out of step during the high-speed operation of the shutter. Such a detection means is required.

  Since a circuit for driving the detection means is also required, there is still a problem that the apparatus is increased in size and cost.

  In addition, in an imaging apparatus equipped with a light amount adjusting device using the above-described stepping motor, particularly a digital still camera, high-speed second control of the shutter speed is required.

  However, when the shutter is closed from the aperture control position, the blade moves to the fully closed position at high speed, which may cause the shutter blade to bounce and re-exposure. You may need to delay the timing. In addition, since it may bounce when moving from the fully closed position to the fully open position, there is a problem that the aperture switching time becomes long.

  The present invention has been made in view of such a problem, and an object thereof is to provide a light amount adjusting device and an imaging device capable of realizing a high speed shutter and a stable stop of a blade using a driving unit. is there.

According to a first configuration of a light amount adjusting device that realizes the object of the present invention, a ground plate having an opening that allows light to pass therethrough, and a linear reciprocating motion guided by the ground plate to reciprocate the opening. A light-shielding blade that opens and closes the blade, a blade drive lever that is disposed along the moving direction of the light-shielding blade, and that has a drive pin that engages with the engagement hole of the light-shielding blade at the tip, and pivots the blade drive lever A light source adjusting device having a drive source,
The base plate has an abutting portion that abuts in the turning direction of the blade driving lever, and the engagement hole formed in the light shielding blade is configured so that the driving pin is shielded from light by the rotation of the blade driving lever. A first elongated hole portion that linearly reciprocates the blade, and a conversion of movement between the swivel movement of the drive pin and the rectilinear reciprocating motion of the light-shielding blade that is connected to at least one end of the first elongated hole portion. second elongated hole operation is formed in the groove amounts to linear reciprocating motion is less than the first long hole portion provided in the tangential direction with respect to the turning locus of the groove, or the drive pin forms a dead zone is not performed and a section, when pre-Symbol shielding blade fully closes the opening of the base plate, the blade driving lever abuts against the abutting portion, said drive pin is positioned at the second long hole portion It is characterized by.

According to a second configuration of the light amount adjusting device for realizing the object of the present invention, as described in claim 2, in the first configuration described above, the second long hole portion is the first long hole portion. It is characterized by being located at both ends.

According to a third configuration of the light amount adjusting device for realizing the object of the present invention, as in claim 3 , in any of the configurations described above, the drive source is configured by a stepping motor, and the drive pin is the first pin. The stepping motor is driven to a position where it is engaged with the second long hole portion.

According to a fourth aspect of the present invention, there is provided an image pickup apparatus that realizes the object of the present invention. And recording an image by transferring the charge of the imaging device.

  According to the present invention, it is possible to prevent bounce of a light-shielding blade such as an aperture shutter blade, to increase the speed of the shutter operation and to prevent double opening. Further, since the fully closed position of the light shielding blade can be guaranteed, the blade position detecting means can be omitted, and the apparatus can be reduced in size and cost.

  Further, it is possible to prevent remaining blades when fully opened, and to achieve quick bounce convergence of the blades after fully opening operation.

  Furthermore, in the control of the stepping motor, the diaphragm shutter blades are driven from the fully open state to the fully closed state at the stop position on the closed side, for example, 3 pulses of 2-phase drive, the excitation phase at 54 ° position, or the fully closed state to the fully open state To hold the damping bounce of the motor in the second slotted hole at the end of the first slotted hole to release the pivoting force of the drive pin, and bounce the blade after the shutter fully closed and fully opened It is possible to prevent this, and the durability of the blade can also be improved.

  In addition, an image pickup apparatus incorporating this light amount adjustment device can quickly transfer charges from the image pickup device, enables quick still image shooting and continuous shooting speed improvement, and realizes a high-speed shutter function. Can be provided.

  In addition, even during continuous shooting, the stabilization time of the aperture shutter blades can be shortened even when the subject undergoes a sudden change in luminance, so that an imaging device capable of stable control can be provided.

  Next, this embodiment will be described in detail with reference to FIGS. Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is an exploded perspective view showing a configuration of a light amount adjusting device according to an embodiment of the present invention, and FIG. 2 is a diagram showing aperture shutter blades provided in the light amount adjusting device shown in FIG. FIG. 2A illustrates a state in which the opening is fully opened, and FIG. 2B illustrates a state in which the opening is fully closed. FIG. 3 is a top view of each aperture shutter blade.

  This light quantity adjusting device includes a stepping motor 6 as a drive source, a blade drive lever 2 fixed to the motor shaft 6 a of the stepping motor 6, and a drive pin protruding from one end of the blade drive lever 2. 2a, a pair of aperture shutter blades 3 and 4 engaged with the drive pin 2a, and a blade cover 5 that is a cover metal plate that regulates and accommodates movement of the pair of aperture shutter blades 3 and 4 in the optical axis direction. The base plate 1 in which the opening 9 is formed is provided.

  This stepping motor 6 is fastened to the main plate 1 with fixing screws 7. The blade cover 5 is fastened to the base plate 1 by a blade cover fixing screw 8.

  Guide pins 1a and 1b projecting from the base plate 1 are provided so as to guide the reciprocating movement of the pair of shutter blades 3 and 4 that overlap in the optical axis direction.

One aperture shutter blade 3 positioned on the image plane side has a aperture portion 3a formed of a hole formed in a circular shape on the tip side, and the other aperture shutter blade 4 positioned on the subject side has a throttle portion 4a made of cutout portions formed in a semicircular shape on the side, also in the width direction on both sides of the pair of the diaphragm shutter blades 3 and 4, the guide pins 1a projecting from the base plate 1 The horizontally elongated holes 3d and 4d that are engaged with each other, and the horizontally elongated holes 3c and 4c that are engaged with the guide pin 1b that protrudes from the base plate 1 are formed.

In the present embodiment, the drive pin 2a projecting on one side of the blade drive lever 2 is inclined with respect to the moving direction of the aperture shutter blades formed at the rear ends of the pair of aperture shutter blades 3 and 4, respectively. The driving cam groove portions 3b and 4b, which are long holes arranged, are engaged. When the stepping motor 6 is rotated in the forward direction from the position shown in FIG. 2A and the blade driving lever 2 is turned in the forward direction, the first aperture shutter blade 3 faces the rear end side and the second aperture straight move in each other opposite directions shutter blade 4 on the tip side and the scan stepping motor 6 from the position shown in FIG. 2 (b) by reverse rotation to pivot the blade drive lever 2 in the opposite direction, the first The aperture shutter blade 3 of the first aperture moves toward the front end side, and the second aperture shutter blade 4 moves linearly toward the rear end side in opposite directions.

At this time, the pair of aperture shutter blades 3 and 4 is guided in linear reciprocating motion by the long holes 3c, 4c and 3d and 4d formed on both sides in the width direction being guided by the guide pins 1a and 1b. The

In this embodiment, the relief cam portions 3e, 4e, 3f, and 4f are provided continuously on both sides of the drive cam groove portion 3b of the first aperture shutter blade 3 and the drive cam groove portion 4b of the second aperture shutter blade 4. Each is formed.

The drive pin 2a projecting from one side of the blade drive lever 2 rotates in the forward and reverse directions while drawing an arc of radius r centered on the motor shaft 6a, and is a drive cam groove portion engaged with the drive pin 2a. 3b and 4b reciprocate the pair of aperture shutter blades 3 and 4 by reciprocating by interfering with the locus drawn by the drive pin 2a. As shown in FIGS. 1 and 2, the blade drive lever 2 is disposed along the moving direction of the aperture shutter blades 3 and 4, and the drive pin 2 a is arranged in the width direction orthogonal to the moving direction of the aperture shutter blades 3 and 4. Turn. On the other hand, the escape grooves 3e, 4e, 3f, and 4f that are connected to both ends of the drive cam grooves 3b and 4b are tangents of the arc drawn by the drive pin 2a at both ends of the drive cam grooves 3b and 4b. It is formed along the direction. Therefore, when the drive pin 2a is disengaged from the drive cam grooves 3b and 4b and enters the escape grooves 3e, 4e, 3f and 4f, the drive pin 2a is restricted with respect to the escape grooves 3e, 4e, 3f and 4f. The shutter blades 3 and 4 become insensitive without any contact state that generates a component force with respect to the reciprocating linear motion direction. In this insensitive state, conversely, no force is generated to rotate the drive pin 2a with respect to the bounce force from the aperture shutter blade, so that the aperture shutter blade is prevented from moving due to the bounce.

  Accordingly, in the rotation range in which the drive pin 2a is disengaged from the drive cam grooves 3b and 4b and engaged with the escape grooves 3e, 4e, 3f and 4f, the drive pin 2a is a pair of aperture shutter blades 3 4 is not allowed to reciprocate linearly. Conversely, even if a force in the direction opposite to the direction driven by the pair of aperture shutter blades 3 and 4 is applied, no force in the rotational direction is applied to the drive pin 2a. The movement in the direction opposite to the driving direction is prevented.

  In addition, the positions of the horizontally elongated holes 3d and 4d of the aperture shutter blades 3 and 4 that engage with one guide pin 1a protruding from the base plate 1 are provided at the cam groove portions 3b and 4b that are disposed obliquely and at both ends thereof. It is desirable to arrange it inside the inflection points with the escape grooves 3e and 4e.

  In the light quantity adjusting device having the above-described configuration, the drive pin 2a protruding from the blade drive lever 2 is engaged in a direction in which the pair of aperture shutter blades 3 and 4 are linearly reciprocated in opposite directions. The aperture shutter blades 3 and 4 linearly reciprocate in opposite directions, and the aperture 9 is formed by the aperture portions 3a and 4a of the aperture shutter blades 3 and 4.

  Then, when the area of the opening 9 changes based on the positional relationship between the diaphragm portions 3a and 4a, the amount of light passing through the opening 9 changes, and light amount adjustment is performed.

  The shutter closing operation is performed by excitation driving of a stepping motor 6 that operates the pair of aperture shutter blades 3 and 4 in the closing direction. As shown in FIG. 3, the pair of aperture shutter blades 3 and 4 are formed with cam groove portions 3b and 4b for driving which are formed by oblique holes arranged to be engaged with one drive pin 2a. Escape groove portions 3e and 4e are formed continuously with one end of the cam groove portions 3b and 4b.

  For this reason, the pair of aperture shutter blades 3 and 4 perform a closing operation at a high speed when the drive pin 2a of the drive lever 2 is engaged with the driving cam groove portions 3b and 4b which are in an interference state and rotated. When rotating along the clearance grooves 3e and 4e in the non-interference state, the blades do not move and the fully closed position can be maintained.

A shutter that shields the opening 9 at a high speed by having a slot portion having a long hole shape as a whole, in which the aperture shutter blades 3 and 4 are provided continuously with the driving cam groove portion to form the relief groove portions 3e (3f) and 4e (4f). Re-exposure (twice-opening) can be prevented even when a so-called bouncing occurs that can be operated and rebounds when the blade driving lever 2 or the aperture shutter blades 3 and 4 come into contact with the base plate 1.
As shown in FIG. 2, the base plate 1 has a contact portion 1 c with which the other side 2 b on the opposite side to the one side where the drive pin 2 a of the drive lever 2 protrudes in the turning direction of the drive lever 2. 1d.

  Furthermore, even if the stop position of the stepping motor, which is a drive source, is slightly deviated due to the bounce, the stop position of the aperture shutter blades 3 and 4 is not affected.

The escape groove portions 3e and 4e may have an arc shape formed with a curvature matching the locus drawn by the drive pin 2a.

  Further, in this embodiment, when the drive pin 2a is engaged with the escape grooves 3e and 4e, it is set so as to create a dead state in which the aperture shutter blades 3 and 4 do not move. However, as shown in FIG. The angle (θ) from the long holes 3b and 4b arranged obliquely may be selected as appropriate to allow a slight movement. In this case, it is possible to eliminate the dead zone when the drive pin 2a starts moving again from the stop position in the opening direction.

  If the inclination of the driving cam groove portions 3b and 4b is 45 ° or less with respect to the moving direction of the blade, the traveling distance of the blade becomes longer with respect to the rotation angle of the driving lever 2, and the driving force of the driving source is increased. In this case, the shutter speed is increased, but the friction is also increased, so that the driving cam grooves 3b and 4b are worn. When the driving force is small, the shutter speed is slowed down as the load increases. When it is 60 ° or more with respect to the moving direction of the aperture shutter blade, the travel distance is shortened, and when the opening is enlarged, the aperture shutter blade is insufficient and cannot be covered by the aperture shutter blade.

  In this embodiment, the angle is set to 48 °, but 45 ° to 60 ° is the most desirable range in terms of design.

  Next, a description will be given of the case of moving from the fully closed state or the predetermined aperture position to the fully open position.

  Even in this case, since the blade drive lever 2 or the aperture shutter blades 3 and 4 come into contact with the main plate 1, so-called bounce occurs, and the position of the blade is not stable for several tens of ms or more. Delay in switching to capture. Further, when the vehicle stops in a bound state, the diaphragm shutter blades 3 and 4 may not completely retract from the opening 9 of the base plate 1, so-called blade remaining may occur.

However, as in the shutter operation, the relief shutter blades 3f and 4f parallel to the rotation direction of the drive pin 2a of the blade drive lever 2 ( tangential direction) are provided at one end of the aperture shutter blade, so that the bounce can be made early. It is possible to converge and prevent the remaining blades.

  The shape of the escape grooves 3f and 4f may be the same as the shape of the escape grooves 3e and 4e on the fully closed side of the aperture shutter blade.

Second Embodiment The drive control of the stepping motor 6 according to the second embodiment will be described below.

  In the present embodiment, the driving for the stepping motor 6 rotates the blade drive lever 2 by 54 ° corresponding to 6 pulses in the 1-2 phase excitation from the fully open state to the fully closed state of the opening 9.

  Further, the stepping motor 6 can be stopped at an arbitrary position, for example, by performing micro-step driving with a sin-cos wave, and the area of the opening 9 can be continuously changed.

  Next, FIG. 4 shows the relationship between the energized states of the two phases A and B, which are the two phases of the stepping motor 6 of this embodiment, the rotation angle of the blade drive lever 2, and the blade operation.

  To change the aperture by continuously changing the area of the opening 9 from the fully open state of the opening 9 as shown in FIG. 2A to the fully closed state of the opening 9 as shown in FIG. From the energized state 0 ° where the opening 9 is fully opened to the energized state 54 ° where the fully closed mechanical end state (for example, the state where the blade drive lever 2 is in contact with the side surface of the main plate 1 and the rotation is mechanically blocked). And the excitation energization of the A phase and B phase of the stepping motor 6 is performed.

For example, in the above embodiment, the diaphragm control is continuously changed by 1-2 phase driving.
In the controlled light amount adjusting device, the electric current of the stepping motor 6 can be changed from the fully open state to the fully closed state by performing the above-described energization operation regardless of the position within the rotation control range of the stepping motor 6. The angle is set to be driven within 360 °. This is because it is possible to omit the position detecting means of the stepping motor 6 or the blade drive lever 2 by performing energization control that does not repeat the same excitation phase in the energization pattern during the 1-2 phase driving of the stepping motor. Further, a circuit for driving the position detecting means is not required. For this reason, size reduction and cost reduction of the light quantity adjusting device can also be realized.

Third Embodiment An image pickup apparatus incorporating the light amount adjusting apparatus shown in each of the above-described embodiments, which is the third embodiment, will be described.

  FIG. 5 shows an example of an image pickup apparatus that records an image by transferring the electric charge of the image pickup element 10 composed of a CCD or the like incorporating the light amount adjusting device of each of the above-described embodiments.

  The stepping motor 6 drives the aperture shutter blades 3 and 4 to a position where an appropriate amount of light is incident on the imaging device 10 by a control circuit (not shown).

  When the release button 11 is pressed to take a still image in this state, a predetermined amount of charge is accumulated in the image sensor 10, the stepping motor 6 rotates at a high speed after a predetermined time has elapsed, and the aperture shutter blades 3 and 4 One opening 9 is shielded. After being completely shielded, the image sensor 10 transfers the charges accumulated in a video recording processing circuit (not shown).

  At this time, since the bounce of the blades when the aperture shutter blades are fully closed is suppressed to a minimum by the light amount adjusting device according to the present invention, the image pickup device 10 is charged immediately after the blades reach the fully closed position of the opening 9. You can start the transfer.

  As a result, the shooting speed of the imaging apparatus can be improved, and the continuous shooting speed is improved. Furthermore, since the aperture 9 can be reliably fully closed without detecting the stop position of the aperture shutter blades 3 and 4, the image pickup apparatus can be reduced in size and cost.

  In addition, when the imaging device continuously shoots and the brightness of the subject changes abruptly, particularly when it changes from a bright state to a dark state, the aperture shutter blades 3 and 4 of the light amount adjusting device are rapidly stepped from the small aperture position. 6 to the fully open position. At this time, since the aperture shutter blades 3 and 4 bounce after being fully opened in the same manner as when fully closed, the subsequent control can be performed only after the blades are stabilized.

  However, according to the present embodiment, the bounds of the aperture shutter blades 3 and 4 can be quickly converged even when fully opened, so that the imaging apparatus can perform the next light quantity control immediately after being fully opened. As a result, it is possible to realize an imaging apparatus capable of quickly adjusting the amount of light even when there is a sudden change in luminance of the subject.

  The present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and various controls are possible. For example, in the above-described embodiment, the driving method of the stepping motor 6 is 1-2 phase excitation or 2-phase excitation driving. However, a driving method such as microstep driving may be used.

1 is an exploded perspective view showing a first embodiment of a light amount adjusting apparatus according to the present invention. The top view of FIG. 1 is shown, (a) represents the fully open state of the aperture shutter blade | wing with which a light quantity adjustment apparatus is equipped, (b) represents the fully closed state similarly. (A) (b) is a figure showing the structure of the cam groove of the blade | wing of FIG. The figure showing the relationship of the energization state of the A phase of a stepping motor which shows the 2nd Example of this invention, a B phase, the rotation angle of a blade drive lever, and a blade | wing operation | movement. Schematic of an imaging apparatus showing a third embodiment according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base plate 1a, 1b ... Guide pin 2 ... Blade drive lever 2a ... Drive pin 3, 4 ... Diaphragm shutter blade 3a, 4a ... Diaphragm part 3b, 4b ... Drive cam groove part 3c, 4c, 3d, 4d ... Horizontal elongate hole 3e 4e, 3f, 4f ... escape groove 5 ... blade cover 6 ... stepping motor 7 ... motor fixing screw 8 ... blade cover fixing screw 9 ... opening 10 ... image sensor 11 ... release button

Claims (4)

A ground plate having an opening through which light passes, a light shielding blade guided by the ground plate to reciprocate linearly to open and close the opening, and arranged along the moving direction of the light shielding blade, In a light quantity adjusting device having a blade drive lever having a drive pin that engages with the engagement hole portion, and a drive source for turning the blade drive lever,
The base plate has an abutting portion that abuts in the turning direction of the blade driving lever, and the engagement hole formed in the light shielding blade is configured so that the driving pin is shielded from light by the rotation of the blade driving lever. A first elongated hole portion that linearly reciprocates the blade, and a conversion of movement between the swivel movement of the drive pin and the rectilinear reciprocating motion of the light-shielding blade that is connected to at least one end of the first elongated hole portion. second elongated hole operation is formed in the groove amounts to linear reciprocating motion is less than the first long hole portion provided in the tangential direction with respect to the turning locus of the groove, or the drive pin forms a dead zone is not performed and a section, when pre-Symbol shielding blade fully closes the opening of the base plate, the blade driving lever abuts against the abutting portion, said drive pin is positioned at the second long hole portion A light quantity adjusting device characterized by the above. It said second elongated hole portion, the light quantity adjusting device according to claim 1, characterized in that located at both ends of the first long hole portion. 3. The light amount adjusting device according to claim 1, wherein the driving source is configured by a stepping motor, and the stepping motor is driven to a position where the driving pin is engaged with the second long hole portion. A light amount adjusting device according to any one of claims 1 to 3 and an image pickup device on which a subject image is formed through the light amount adjusting device, and transferring an electric charge of the image pickup device to record an image. An imaging apparatus characterized by the above.

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