JP4216621B2 - Shutter for digital still camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens shutter used in a digital still camera.
[0002]
[Prior art]
In most cases, a lens shutter for a digital still camera, like a lens shutter for a silver halide camera, has two shutter blades rotated relatively by the same drive source, and a circular opening for a photographing optical path. As the shape of the opening regulating edge of the shutter blade, a complicated curved shape (for example, see Patent Document 1) and a straight shape (for example, see Patent Document 2) Is known. In the former shape, the two shutter blades start to open the opening from the approximate center (optical axis position) and finish closing toward the center, so that the shutter blade is also used as the aperture blade. Although advantageous in some cases, the shape of each blade is larger for the size of the opening in order to prevent collision between the tips of the two during the closing operation. On the other hand, in the latter shape, there is no risk of collision between the two at the time of closing operation, so the shape of each blade is reduced, which is advantageous for making the shutter unit compact. I can't. The present invention relates to a lens shutter for a digital still camera including the latter shape of shutter blades.
[0003]
[Patent Document 1]
Japanese Patent Publication 2001-215554 (page 4-7, Fig. 1-4)
[Patent Document 2]
Japanese Patent Publication No. 2002-162666 (page 3-5, FIG. 1-6)
[0004]
[Problems to be solved by the invention]
When the lens shutter is employed in a digital still camera, and the shutter blade does not serve as the diaphragm blade, the exposure to the solid-state imaging device for photographing is performed with the opening for the photographing optical path fully opened, It starts by releasing the charge accumulated in the solid-state image sensor. In addition, the exposure started in such a manner is normally terminated when the shutter blade closes the opening, and the imaging information is transferred to the storage device in the closed state. However, it is also known that the above-described exposure is terminated by an electric signal to the solid-state imaging device, and the shutter blade is closed only for transferring the imaging information to the storage device. In these cases, it is required that the time from when the shutter blade starts to close to when it closes is as short as possible. That is, if the closing time from the start of closing the opening to the end of closing is long, it causes the exposure unevenness to increase in the former case, and causes the occurrence of smear phenomenon to increase in the latter case. Because it becomes.
[0005]
By the way, as described above, the diameter of the opening to be opened and closed is the same for the shutter blade having a curved opening regulating edge and the shutter blade having a straight shape, and the shutter blade is located from the mounting position of the shutter blade. Assuming that the distance to the optical axis is the same and the operating speed is also the same, the closing time is shorter for the former shutter blade than for the latter shutter blade. This is because, in the case of the former shutter blades, the closing time is when the optical axis position of the opening is closed. In the case of the latter shutter blades, the shutter is closed when the optical axis position is closed. This is because the region on the tip side of the blade is still closed.
[0006]
Therefore, in order to close the latter shutter blade in a short time, it is necessary to increase the power of the drive source and operate at a high speed. However, there is a limit to such a high speed, and if the speed is increased too much, the shutter blade is closed. Measures against bounce caused by abutting against the stopper at the time of stopping and measures against destruction of the shutter blades are also troublesome. The shutter described in Patent Document 2 has been devised to make the closing point earlier without increasing the force of the drive source, and is extremely effective in that respect. However, since it is necessary to provide play between the connecting hole formed in the shutter blade and the drive pin or to devise the shape of the connecting hole, the shutter blade does not completely interlock with the operation of the drive pin, Even when the closing operation is performed, the operation is started with a slight delay. Accordingly, it cannot be said that there are no problems associated therewith, and depending on the required specifications of the camera, it is necessary to take measures to overcome them.
[0007]
The present invention has been made in order to solve such problems. The object of the present invention is to provide two shutter blades each having a straight opening regulating edge formed by a driving means. In a conventional lens shutter that reciprocally rotates in opposite directions and starts to open a circular opening for a photographing optical path from its predetermined peripheral position during opening operation, and finishes closing at the peripheral position during closing operation. Auxiliary blades that are reciprocated substantially linearly by the driving means are provided, and at the time of closing operation, the shutter blades close the opening by closing the opening from the peripheral position toward the optical axis by the auxiliary blade. To provide a shutter for a digital still camera that can shorten the time from the start to the end of closing.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a shutter for a digital still camera according to the present invention has two ground planes in which a circular opening for a photographing optical path is formed in at least one and constitutes a blade chamber therebetween. Each opening regulating edge is formed in a straight line so as to be reciprocally rotatable in opposite directions in the blade chamber, and the opening is opened from its predetermined peripheral position by the opening regulating edge during opening operation. First, two shutter blades that are closed at the peripheral position at the time of closing operation, and a reciprocating operation in a substantially linear shape within the blade chamber are arranged so that the shutter blade can be reciprocated. An auxiliary blade that closes toward the shaft and opens toward the peripheral position during the opening operation of the shutter blade, and a reciprocating operation, and the two shutter blades and the auxiliary blade are open. So that and a driving means for reciprocating the blade simultaneously.
[0009]
In that case, the drive means has a permanent magnet rotor that can be reciprocally rotated in a predetermined angular range in a direction corresponding to the energization direction of the stator coil, and its output pin is connected to the two shutter blades. A current-controlled motor that is fitted in the formed long hole and the long hole formed in the auxiliary blade, and in the open position of the opening, even if the current to the stator coil is cut off, If the rotor is kept stopped by the magnetic force of its permanent magnet, an electric compact shutter unit can be obtained.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the illustrated examples. 1 to 4 are all plan views showing examples, and FIG. 1 shows an initial state before photographing. FIG. 2 shows the moment when the shutter blades are activated from the state shown in FIG. 1 at the end of photographing and begin to close the photographing optical path opening. FIG. 3 shows the state shown in FIG. After that, the moment when the photographing optical path opening is closed is shown. Further, FIG. 4 shows a state in which the operation of the shutter blades is stopped immediately after the state shown in FIG.
[0011]
First, the configuration of the embodiment will be described mainly with reference to FIG. The shutter base plate 1 is attached with an auxiliary base plate 2 by an appropriate means (not shown), and a blade chamber is formed between the two. In FIG. 1, a part of the shutter base plate 1 is cut out so that a part of the blade chamber can be seen. In the present embodiment, the shutter base plate 1 and the auxiliary base plate 2 are separated from each other. Have substantially the same planar shape. And circular opening part 1a, 2a is formed in the center part of those two ground boards 1,2. Usually, one of the two openings 1a and 2a is often configured to restrict the photographing optical path opening, but in the case of this embodiment, the diameters of both are exactly the same.
[0012]
In the blade chamber, the auxiliary blade 3, the shutter blade 4, and the shutter blade 5 are arranged in this order from the shutter base plate 1 side. Among them, the auxiliary blade 3 has an opening 3a having a diameter larger than the above-described openings 1a and 2a and three long holes 3b, 3c and 3d, and among them, the long holes 3b and 3c are shuttered. It fits into pins 1b and 1c installed upright on the main plate 1 so that it can be operated in a substantially vertical direction in FIG. The two shutter blades 4 and 5 have long holes 4a and 5a, and are rotatably attached to shafts 1d and 1e provided upright on the shutter base plate 1.
[0013]
A current control type motor called a moving magnet type motor or the like is attached to a surface outside the blade chamber of the shutter base plate 1. Since this type of motor is well known, the detailed configuration is not shown. However, the rotor 6 is a bearing in a position overlapping the shaft 1e inside the stator frame 7 made of synthetic resin. Has been. The rotor 6 includes a permanent magnet magnetized in two radial directions (in FIG. 1, the magnetic poles are indicated by N and S, and the boundary line is indicated by a one-dot chain line). An output pin 6a is provided at the tip of the arm portion extending in the radial direction. The output pin 6a passes through an arc-shaped long hole (not shown) formed in the shutter base plate 1, and in the blade chamber, the long holes 3d, 4a, 5a is fitted.
[0014]
In addition, a groove is formed on the outside of the stator frame 7, and a coil 8 is wound around the groove so as to surround the two bearing portions of the rotor 6. 8 is rotated in a predetermined angle range in a direction corresponding to the energization direction to 8. Furthermore, two elongated grooves are formed on the outer circumferential surface of the stator frame 7 in parallel with the rotation axis of the rotor 6, and an elongated columnar magnetic bar (iron pin) is formed therein. 9, 10 are fitted. A cylindrical yoke 11 is fitted on the outside of the stator frame 7. The arc-shaped long hole (not shown) formed in the shutter base plate 1 also serves as a stopper for the rotation of the rotor 6 by causing both ends in the length direction to contact the output pin 6a. It is supposed to be.
[0015]
Next, the operation of this embodiment will be described with reference to FIGS. FIG. 1 shows an initial state before photographing. The camera is turned on and the subject image can be observed by the monitor, but the motor coil 8 is not energized. Nevertheless, the three blades 3, 4 and 5 can maintain a state in which the opening 1a is fully opened. That is, the magnetic rods 9 and 10 are opposed to the peripheral surfaces of the S pole and N pole of the rotor 6, but it is close to the peripheral surface position that forms 90 ° with the boundary line (one-dot chain line) of the magnetic pole. This is a magnetic rod 10. Therefore, the attractive force acting between the N pole and the magnetic rod 10 is larger than the attractive force acting between the S pole and the magnetic rod 9, so that the rotor 6 is counterclockwise. A rotating force is applied. This is because the output pin 6a of the rotor 6 is in contact with the upper end of an arc-shaped elongated hole (not shown) formed in the shutter base plate 1 and is prevented from rotating.
[0016]
When shooting, the release button (switch) is pushed in the state shown in FIG. Then, the electric signal stored in the solid-state image sensor is released by the electrical signal from the control circuit, and exposure (charge accumulation) for photographing is started immediately after the completion of the emission, and the exposure is controlled by the exposure time control circuit. Counting of a predetermined time corresponding to the time is started. After that, when the count ends, the motor coil 8 is energized in the positive direction. Accordingly, the rotor 6 is rotated clockwise from the state shown in FIG. 1, and the shutter blade 4 is rotated clockwise and the shutter blade 5 is rotated counterclockwise by the output pin 6a. The blade 3 is operated downward. FIG. 2 shows a state at the moment when the three blades 3, 4 and 5 start to close the opening 1 a.
[0017]
The shutter blades 4 and 5 of the present embodiment have the same shape, and are disposed so that one of them is reversed with respect to the other. For this reason, the edge in the closing operation direction has the shape of the shutter blade 4 having a "<" shape and the shutter blade 5 has an inverted shape of "<", and each has two linear edges. . However, as can be seen from FIG. 2, it is only the straight edge on the tip side that closes the opening 1 a from this state. Accordingly, also in this embodiment, the two shutter blades 4 and 5 that rotate relatively to open and close the opening 1a (that is, the photographing optical path opening) have linear opening restriction edges. become.
[0018]
When the rotor 6 still rotates clockwise from the state of FIG. 2, the shutter blades 4 and 5 close the opening 1a from the left and right lower positions by the straight opening restriction edges, and the auxiliary base plate 3 is The opening 1a is closed from the upper position in the optical axis direction by the arc-shaped opening regulating edge. FIG. 3 shows the moment when the opening 1a has been closed in this way. At this time, if only the shutter blades 4 and 5 are considered, the opening 1a is not completely closed. Therefore, when the auxiliary blade 3 is not provided, the time until the opening 1a is completely closed becomes longer. In this way, the three blades 3, 4, 5 continue to operate even after the opening 1 a is closed, and the output pin 6 a is an arc-shaped elongated hole (not shown) formed in the shutter base plate 1. It stops when it touches the lower end surface. This state is shown in FIG.
[0019]
As described above, in the case of the present embodiment, the opening 1a is closed at the timing shown in FIG. 3, so that the imaging information accumulated in the solid-state imaging device can be stored in the storage device anytime thereafter. It is possible to transfer. In other words, the transfer completion time can be accelerated, the opening 1a can be fully opened quickly, and preparation for the next shooting can be made. Preferred.
[0020]
Further, in the present embodiment, when it is desired to maintain the state shown in FIG. 4 for a predetermined time, it is safe to cut off the power supply to the coil 8 for power saving. That is, in this state, the attractive force acting between the south pole and the magnetic rod 9 is larger than the attractive force acting between the north pole and the magnetic rod 10, and the rotor 6 has This is because a clockwise rotating force is applied. Therefore, if such a function is not required, the magnetic rod 9 need not be provided.
[0021]
When the imaging information accumulated in the solid-state imaging device is transferred to the storage device in this manner, the coil 8 is energized in the reverse direction. Therefore, the rotor 6 rotates counterclockwise from the state of FIG. 4, operates the auxiliary plate 3 upward, rotates the shutter blade 4 clockwise, and rotates the shutter blade 5 counterclockwise. Thereby, the opening 1a is opened, and immediately after the opening 1a is fully opened, the output pin 6a comes into contact with the upper end surface of an arc-shaped long hole (not shown) formed in the shutter base plate 1, and the opening operation is performed. finish. After that, the state where the power supply to the coil 8 is cut off is the initial state shown in FIG.
[0022]
As described above, in this embodiment, the two shutter blades 4 and 5 whose opening regulating edges are formed in a straight line are reciprocally rotated in opposite directions by the output pin 6a of the motor, and the photographing optical path opening (opening) 1a) is a lens shutter for a digital still camera of the type configured to start to open from its predetermined peripheral position during opening operation and finish closing at its peripheral position during closing operation, Since the time from the start of closing to the end of closing can be made shorter than before, when the closing operation is performed after the exposure for shooting is completed, the occurrence of smear phenomenon is prevented. If the exposure for photographing is finished simultaneously with the end of the closing operation, uneven exposure can be suppressed. Furthermore, in the latter case, it is needless to say that the highest shutter speed (effective exposure time) can be increased.
[0023]
In the above embodiment, the opening / closing operation of the three blades 3, 4, 5 is directly performed by a current control type motor, but the present invention is not limited to such a configuration. A mediating member may be interposed. Also, the configuration of the current control type motor is not limited to the configuration of the embodiment, and any configuration may be used, and a step motor may be used instead of the current control type motor. Furthermore, although not very practical, the opening operation may be driven by a motor and the closing operation may be driven by a spring.
[0024]
【The invention's effect】
As described above, in the lens shutter of the present invention, the two shutter blades whose opening restriction edges are formed in a straight line are reciprocally rotated in opposite directions by the driving means, and the circular opening for the photographing optical path is In the opening operation, the auxiliary blades are started to be opened from the predetermined peripheral position, and in the closing operation, the auxiliary vanes are made to be substantially linear by the above drive means in the closing operation even though it is configured to finish closing at the peripheral position. Since the opening is closed from the peripheral position toward the optical axis, the time from the start of closing the opening to the end of the opening is shortened, which is extremely suitable for use in a digital still camera. It is.
[Brief description of the drawings]
FIG. 1 is a plan view of an embodiment showing an initial state before photographing.
FIG. 2 is a plan view showing a moment when shutter blades are operated from the state shown in FIG. 1 at the end of photographing and start to close the photographing optical path opening;
FIG. 3 is a plan view showing the moment when the photographing optical path opening is closed after the state shown in FIG. 2;
4 is a plan view showing a state in which the operation of the shutter blades is stopped immediately after the state shown in FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a, 2a, 3a Opening part 1b, 1c Pin 1d, 1e Axis 2 Auxiliary base plate 3 Auxiliary blade 3b, 3c, 3d, 4a, 5a Long hole 4, 5 Shutter blade 6 Rotor 6a Output pin 7 Stator frame 8 Coil 9, 10 Magnetic bar 11 Yoke

Claims (2)

A circular opening for the photographing optical path is formed in at least one of the two ground plates constituting the blade chamber between them, and each opening regulating edge is formed in a straight line, and there is a conflict between the blade chamber. Two shutter blades which are arranged so as to be reciprocally rotatable in a direction to be opened and start opening the opening from its predetermined peripheral position by the opening restricting edge at the time of opening operation and finish closing at the peripheral position at the time of closing operation, The reciprocating operation is arranged substantially linearly in the blade chamber, and the opening is closed from the peripheral position toward the optical axis when the shutter blade is closed, and toward the peripheral position when the shutter blade is open. Auxiliary blades to be opened and drive means capable of reciprocating operation and reciprocating the two shutter blades and the auxiliary blades at the same time are provided. Shutter for digital still camera. The drive means has a permanent magnet rotor that is reciprocally rotated in a predetermined angular range in a direction corresponding to the energization direction of the stator coil, and an output pin thereof is formed on the two shutter blades. A motor of current control type that is fitted in a long hole and a long hole formed in the auxiliary blade, and the rotor remains in the open position of the opening even if the current to the stator coil is cut off. The shutter for a digital still camera according to claim 1, wherein the stop state is maintained by the magnetic force of the permanent magnet.

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