JP2015105989A - Focal plane shutter and camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase resolution of a detection object member detected by an optical sensor while achieving simplification, miniaturization, and so on of a structure in a focal plane shutter.SOLUTION: A focal plane shutter includes a plate 10 with an aperture for exposure, a blade member 40 freely movably provided on the plate so as to open/close the aperture, a driving member 60 for driving the blade member, a detection object plate 80 moved according to the blade member, and an optical sensor 90 disposed so as to face the detection object plate. The detection object plate 80 includes; a plurality of slits 83a and 84a formed to open radially at intervals of a prescribed angle; and light-transmissive plate parts 83b and 84b which are disposed in each of the plurality of slits so as to equally divide the slit in a circumferential direction and have prescribed light transmissivities. Thus the resolution of the detection object plate detected by the optical sensor can be increased while simplification, miniaturization, and so on of a structure are achieved.

Description

  The present invention relates to a focal plane shutter provided with a blade member that opens and closes an opening for exposure and a detection sensor that detects the position of the blade member, and the like, and more particularly, a digital video that requires high-precision, high-resolution control and downsizing. The present invention relates to a focal plane shutter applied to an optical apparatus such as a camera or a digital still camera, and a camera using the focal plane shutter.

As a conventional focal plane shutter, a substantially rectangular base plate having an opening for exposure, a front blade and a rear blade (blade member) movably provided on the base plate to open and close the opening, and a tip for driving the front blade A blade driving member, a rear blade driving member for driving the rear blade, a pulse plate (detected plate) provided on each of the front blade driving member and the rear blade driving member to detect the positions of the front blade and the rear blade, A device provided with an optical sensor or the like arranged so as to face each other is known (for example, see Patent Document 1).
However, in this focal plane shutter, the pulse plate has a substantially fan-shaped outline and a plurality of radially extending slits formed at intervals of a predetermined angle. Therefore, the number of slits is increased to increase the resolution. However, there is a limit due to constraints such as material strength. On the other hand, even if it is possible to increase the number of slits while securing the strength by enlarging the fan-shaped pulse plate, the pulse plate becomes larger and the focal plane shutter as a whole In addition, when the pulse plate rotates together with the leading blade driving member and trailing blade driving member, the moment of inertia increases, the load applied to the driving portion increases, and quick shutter operation becomes difficult. is there.

Further, as a device for detecting the position of the blade member, there are a substantially disk-shaped ground plate having an opening for exposure, a pair of shutter blades also serving as a diaphragm provided movably on the ground plate to open and close the opening, There are known motors that open and close the shutter blades, a plurality of slit rows (long hole rows) formed in one shutter blade, and an optical sensor arranged so as to face the slit rows ( For example, see Patent Document 2).
However, in this apparatus, the detection slit row is integrally formed by drilling a part of the shutter blade, so that the shutter blade is enlarged and the moment of inertia is increased, and the entire apparatus is enlarged. It invites.

JP 2007-240783 A Japanese Patent Laid-Open No. 6-332035

  The present invention has been made in view of the above circumstances, and its object is to improve the resolution of a member to be detected detected by an optical sensor while simplifying the structure and reducing the size. Another object of the present invention is to provide a focal plane shutter suitable for optical equipment such as a digital video camera and a digital still camera that require high precision and high resolution control and downsizing, and a camera using the focal plane shutter.

The focal plane shutter of the present invention includes a ground plate having an opening for exposure, a blade member movably provided on the ground plate to open and close the opening, a drive member for driving the blade member, and a linkage with the blade member. A focal plane shutter having a plate to be detected and an optical sensor arranged to face the plate to be detected, wherein the plate to be detected is radially opened at a predetermined angle interval. A plurality of slits, and a light transmission plate portion having a predetermined light transmittance disposed in each of the plurality of slits so as to equally divide the plurality of slits in the circumferential direction.
According to this configuration, when the blade member is driven to open and close by the driving member, the detected plate that is interlocked with the blade member is detected by the optical sensor, so that the position (or speed) of the blade member is detected. Can do.
Here, since the plate to be detected has a light transmitting plate portion arranged so as to equally divide the slit (bisected, bisected, etc.) in the plurality of slits arranged in the circumferential direction, only the slit is provided. Compared with the above, the resolution can be increased by the increase of the light transmission plate portion, and therefore the blade member can be controlled with high accuracy and high resolution, and the light transmission plate adjacent to the slit. Since only the portion is provided, the structure can be simplified and reduced in size, and can be preferably applied to an optical apparatus such as a digital video camera and a digital still camera that are required to be downsized.

In the above configuration, the plate to be detected has a light-shielding substrate having a plurality of slits that are radially opened at a predetermined angle interval, and a plurality of slits that are radially opened at a predetermined angle interval. In addition, a configuration including a transmissive thin plate having a predetermined light transmittance laminated on a light-shielding substrate can be employed.
According to this configuration, since the transmissive thin plate is laminated on the light-shielding substrate, if there is a limit to mechanical processing, the desired processing can be performed by performing processing such as thin film technology on the transmissive thin plate. A plurality of slits can be formed at a pitch, and mechanical strength can be secured with a relatively thick light-shielding substrate, so that it is possible to easily achieve both mechanical strength and high resolution. In particular, high resolution can be achieved by using a plurality of threshold values set based on information on the amount of light in the opening of the slit and the portion of the transmissive thin plate (light transmissive plate portion).

In the above configuration, the plate to be detected has a plurality of slits formed by opening radially at intervals of a predetermined angle, and has a first transmissive thin plate having a first light transmittance, and radially at intervals of the predetermined angle. A second transmissive thin plate having a plurality of slits formed to be open and having a second light transmittance laminated with the phase of the slits shifted from each other with respect to the first transmissive thin plate; A configuration including a transparent substrate on which the thin plate and the second transmissive thin plate are laminated can be employed.
According to this configuration, since the first transmissive thin plate and the second transmissive thin plate are laminated with the phase of the slit being shifted with respect to the transparent substrate, the first transmissive thin plate and the second transmissive thin plate are laminated. By applying processing such as thin film technology, a plurality of slits can be formed at a desired pitch, and mechanical strength can be secured with a relatively thick transparent substrate. It is possible to easily achieve both high resolution and high resolution. In particular, the slit opening, the first transmissive thin plate (the light transmissive plate portion forming the first light transmittance), the second transmissive thin plate (first Part of the light transmission plate portion having a light transmittance of 2), the first light transmission thin plate and the second light transmission thin plate are overlapped (the light transmission plate portion where the first light transmittance and the second light transmittance are overlapped) ) By using multiple thresholds set based on the light quantity information It is possible to achieve a functionalised.

In the above configuration, the transparent substrate may include a pair of transparent substrates that sandwich the first transmissive thin plate and the second transmissive thin plate.
According to this configuration, since the first transmissive thin plate and the second transmissive thin plate are sandwiched between the transparent substrates from both sides, the mechanical strength can be further increased while increasing the resolution.

The above configuration includes a support shaft that rotatably supports the drive member around a predetermined axis, and the detected plate is detachably attached to the support shaft so as to rotate integrally with the drive member. The configuration can be adopted.
According to this configuration, since the plate to be detected is detachably attached to the support shaft of the drive member and rotates integrally with the drive member, the blade member while reducing the moment of inertia of the blade member, etc. Can perform a quick shutter operation, and can detect the position (or speed) of the blade member with high accuracy.

In the above configuration, the blade member includes a plurality of blade main bodies and a plurality of arms that connect the plurality of blade main bodies, and the detection plate is attached so as to rotate integrally with the arms. be able to.
According to this configuration, since the plate to be detected is formed to be relatively small and light, it can be attached so as to rotate integrally with the plate constituting the blade member. ) And the like can be directly detected with high accuracy.

The camera of the present invention includes a focal plane shutter having any one of the above-described configurations.
According to this configuration, it is possible to obtain a camera capable of high-precision and high-resolution control by increasing the resolution of the detected member detected by the optical sensor while achieving simplification and downsizing of the structure. .

  According to the focal plane shutter having the above-described configuration, the resolution of the detected member detected by the optical sensor is increased while achieving the simplification and downsizing of the structure, and the high precision, high resolution control, downsizing, etc. Therefore, it is possible to obtain a focal plane shutter and a camera suitable for optical equipment such as a digital video camera and a digital still camera.

FIG. 3 is a plan view showing a focal plane shutter according to an embodiment of the present invention and showing a state in which blade members (front blade and rear blade) have completed a shutter operation (exposure operation). FIG. 2 is a plan view showing a focal plane shutter according to an embodiment of the present invention and showing a state immediately before a shutter operation (exposure operation) in which blade members (front blade and rear blade) are charged. FIG. 3 is a partial perspective exploded view partially showing a drive member that forms part of a focal plane shutter according to the present invention, a support shaft that supports the drive member, a plate to be detected, an optical sensor, and a blade member. 1 shows one embodiment of a plate to be detected (fixed to a support shaft) included in a focal plane shutter according to the present invention, and (a) is a plane showing a plate to be detected and an optical sensor in the state shown in FIG. FIG. 2B is a plan view showing the plate to be detected and the optical sensor in the state shown in FIG. It is a disassembled perspective view of the to-be-detected plate (a pair of transparent substrate, 1st transparent thin plate, 2nd transparent thin plate) shown in FIG. FIG. 6 is a plan view showing a state in which a first transmissive thin plate and a second transmissive thin plate included in the detection plate shown in FIG. 5 are laminated. FIG. 6 is a plan view showing a first light-shielding thin plate and a second light-transmitting thin plate included in the detection plate shown in FIG. 5. FIG. 6 shows another embodiment of the plate to be detected (fixed to the support shaft) included in the focal plane shutter according to the present invention, and (a) shows the plate to be detected and the optical sensor in the state shown in FIG. 1. FIG. 4B is a plan view showing the plate to be detected and the optical sensor in the state shown in FIG. It is a top view which shows the to-be-detected plate shown in FIG. FIG. 10 is a plan view showing a light-shielding substrate and a transmissive thin plate that constitute the plate to be detected shown in FIG. 9. FIG. 10 is a plan view showing another embodiment of a focal plane shutter according to the present invention, in which a blade member (front blade and rear blade) has completed a shutter operation (exposure operation). FIG. 9 is a plan view showing another embodiment of a focal plane shutter according to the present invention, and showing a state immediately before a shutter operation (exposure operation) in which blade members (front blade and rear blade) are charged. In the focal plane shutter shown in FIGS. 11 and 12, (a) is a plan view showing the plate to be detected and the optical sensor in the state shown in FIG. 11, and (b) is the plate and optical sensor to be detected in the state shown in FIG. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
As shown in FIGS. 1 and 2, the focal plane shutter according to this embodiment is provided so as to be movable with respect to a substantially rectangular base plate 10, a support plate 20 arranged and fixed in parallel to the base plate 10, and the base plate 10. The leading blade 30 as a blade member, the trailing blade 40 as a blade member provided movably with respect to the main plate 10, the leading blade drive lever 50 as a driving member for driving the leading blade 30, and the trailing blade 40 are driven. A set member (not shown) for setting the trailing blade driving lever 60, leading blade driving lever 50, and trailing blade driving lever 60 as driving members to be set to the setting position before the shutter operation, and leading blade driving lever 50 set to the setting position And the two electromagnets 71 and 72 for attracting and holding the rear blade drive lever 60, and the detected plate 8 provided to rotate integrally with the rear blade drive lever 60. , And a light sensor 90 or the like which is disposed to face the object to be detected plate 80.

As shown in FIGS. 1 and 2, the base plate 10 is formed in a substantially rectangular flat plate shape, and has a substantially rectangular opening 10 a for exposure, a long hole 10 b in which an arc portion and a semicircular portion are continuous, and a long length. Hole 10c, support shafts 10d and 10e erected to rotatably support the leading blade 30, support shafts 10f and 10g erected to rotatably support the rear blade 40, and a leading blade drive lever 50 10h, a support shaft 10i for rotatably supporting the rear blade drive lever 60, a support shaft (not shown) erected to support the set member for rotation. ing.
An intermediate plate (not shown) that defines a blade chamber that houses the leading blade 30 and a back plate (not shown) that defines the blade chamber that houses the trailing blade 40 are fixed to the base plate 10 at predetermined intervals. Has been.
The support plate 20 is formed so as to hold the two electromagnets 71 and 72 and fit and support the tip portions of the support shafts 10h and 10i.

As shown in FIGS. 1 and 2, the leading blade 30 is composed of four blade bodies 31, 32, 33, 34 and two arms 35, 36 that connect the blade bodies 31, 32, 33, 34. Yes.
The arm 35 is rotatably supported by the support shaft 10 d and a part of the arm 35 is connected to the drive pin 50 a of the leading blade drive lever 50.
The arm 36 is rotatably supported by the support shaft 10e.
Then, as shown in FIG. 1, the arm 35 is driven upward (clockwise) in the drawing by the leading blade driving lever 50, whereby the four blade bodies 31, 32, 33, 34 are moved. On the other hand, the opening 10a is overlapped, and as shown in FIG. 2, the four blade main bodies 31 are driven by being driven downward (counterclockwise) in the figure by the leading blade driving lever 50, as shown in FIG. 32, 33, and 34 are developed to close the opening 10a.

As shown in FIGS. 1 and 2, the rear blade 40 is composed of four blade bodies 41, 42, 43, 44 and two arms 45, 46 that connect the blade bodies 41, 42, 43, 44. Yes.
The arm 45 is rotatably supported by the support shaft 10 f and a part of the arm 45 is connected to the drive pin 60 a of the trailing blade drive lever 60.
The arm 46 is rotatably supported by the support shaft 10g.
Then, as shown in FIG. 1, the arm 45 is driven upward (clockwise) in the figure by the rear blade drive lever 60, whereby the four blade bodies 41, 42, 43, 44 are moved. As shown in FIG. 2, the four blade main bodies 41 are developed by being expanded and closed by opening the rear blade driving lever 60 downward (counterclockwise) as shown in FIG. , 42, 43, 44 overlap each other to open the opening 10a.

  The leading blade driving lever 50 includes a driving pin 50a to which the arm 35 is coupled, an engaging portion 50b to which a set member is engaged and a rotational force is exerted counterclockwise, an attracted portion 50c to be attracted by the electromagnet 71, and a support A cylindrical portion 50d and the like for fitting the shaft 10h are provided, and are urged to rotate clockwise in FIGS. 1 and 2 by a biasing spring such as a torsion coil spring (not shown) disposed around the support shaft 10h. And is rotatably supported by a support shaft 10h.

  The rear blade drive lever 60 includes a drive pin 60a to which the arm 45 is coupled, an engagement portion 60b to which a set member is engaged and a rotational force is exerted counterclockwise, an attracted portion 60c that is attracted by an electromagnet 72, and a support A cylindrical portion 60d for fitting the shaft 10i, a positioning portion 60e for attaching and positioning the plate 80 to be detected, and the like are provided, and an urging spring such as a torsion coil spring (not shown) arranged around the support shaft 10i is used. 1 and 2 is urged to rotate clockwise and supported rotatably by a support shaft 10i.

  The electromagnets 71 and 72 are held by the support plate 20 and face the attracted portions 50c and 60c of the leading blade driving lever 50 and the trailing blade driving lever 60 rotated counterclockwise by the set member, respectively. An electromagnetic force is generated by energization to exert an attracting force on the attracted portions 50c and 60c.

  In the above configuration, the leading blade driving lever 50 is rotatably supported by the support shaft 10h and is urged to rotate clockwise by the urging spring, and the driving pin 50a is inserted into the elongated hole 10b to It is connected to the arm 35 and is rotated clockwise by the biasing spring in the resting state to move the leading blade 30 to the open position, while being rotated counterclockwise by the set member to close the leading blade 30 When the electromagnet 71 is energized, the attracted part 50c is attracted and held at the set position before the shutter operation. By de-energizing the electromagnet 71, the attraction by the magnetic force is released, and the biasing spring is attached. The leading blade 30 is rotated clockwise by the force to move it to the open position.

  The rear blade drive lever 60 is rotatably supported by the support shaft 10i and is urged to rotate clockwise by the urging spring, and the drive pin 60a is inserted into the long hole 10c so that the arm 45 of the rear blade 40 is provided. And is rotated clockwise by the biasing spring in the resting state to move the rear blade 40 to the closed position, while being rotated counterclockwise by the set member to bring the rear blade 40 to the open position. When the electromagnet 72 is energized, the attracted portion 60c is attracted and held at the set position before the shutter operation. It is rotated clockwise to move the rear blade 40 to the closed position.

As shown in FIGS. 3 and 4, the plate 80 to be detected is positioned by the positioning portion 60e in contact with the end face of the trailing blade driving lever 60 and supported so as to rotate the trailing blade driving lever 60 integrally. The shaft 10i is detachably attached (using a biasing spring or the like for biasing in the thrust direction as necessary).
As shown in FIG. 5, the detection plate 80 includes a pair of transparent substrates 81 and 82, a first transmissive thin plate 83 and a second transmissive thin plate 84 which are stacked so as to be sandwiched between the pair of transparent substrates 81 and 82. It is comprised by.

As shown in FIG. 5, the transparent substrate 81 includes a fitting hole 81a into which the support shaft 10i is fitted, a positioning hole 81b into which the positioning part 60e is fitted, a transparent flat plate part 81c having a substantially fan shape, and the like. .
As shown in FIG. 5, the transparent substrate 82 is slightly thinner than the transparent substrate 81, and has a fitting hole 82a into which the support shaft 10i is fitted, a positioning hole 82b into which the positioning portion 60e is fitted, and a substantially fan shape. And a transparent flat plate portion 82c.

The first transparent thin plate 83 is formed of a thin plate-like flexible substrate or a thin film material having the first light transmittance, and as shown in FIGS. 3 and 7, the outer contour is formed in a substantially fan shape, A plurality of slits 83a formed radially with an interval of a predetermined angle 2θ around the axis S (of the support shaft 10i), a light transmission plate portion 83b formed between the slits 83a and 83a, and a positioning portion A fitting hole 83c and the like for fitting 60e are provided.
Here, the circumferential width (angle) of the slit 83a is formed as an angle θ, and the circumferential width (angle) of the light transmission plate portion 83b between the slits 83a and 83a is formed as an angle θ.

The second transparent thin plate 84 is formed of a thin plate-like flexible substrate or a thin film material having the second light transmittance. As shown in FIGS. 3 and 7, the outer contour is formed in a substantially fan shape. A plurality of slits 84a formed by opening radially about the axis S (of the support shaft 10i) at an interval of a predetermined angle 2θ, a light transmitting plate portion 84b formed between the slits 84a and 84a, and a positioning portion A fitting hole 84c for fitting 60e is provided.
Here, the circumferential width (angle) of the slit 84a is formed as an angle θ, and the circumferential width (angle) of the light transmission plate portion 84b between the slits 84a and 84a is formed as an angle θ.

Then, as shown in FIG. 6, the first transmissive thin plate 83 and the second transmissive thin plate 84 are laminated so that the phases of the slits 83a and 84a are shifted by an angle θ / 2.
As a result, as shown in FIG. 6, in the detection plate 80, the light transmission plate portion 80a having the first light transmittance, the first light transmittance portion and the second light transmittance portion overlap each other. The four regions of the light transmitting plate portion 80b, the light transmitting plate portion 80c having the second light transmittance, and the opening portion 80d where the slit 83a and the slit 84a overlap each other are formed so as to be repeated every angle 2θ.
Therefore, the amount of light passing through these four areas is detected by the optical sensor 90, and by using a plurality of (four) threshold values set based on the detection information, the resolution can be improved as compared with the case of only a slit. Can be increased.
Further, the light transmitting plate portion 80a that forms the first light transmittance → the light transmitting plate portion 80b in which the first light transmittance portion and the second light transmittance portion overlap → the second light transmittance. By reading the order and elapsed time of the opening 80d where the light transmitting plate portion 80c → the slit 83a and the slit 84a overlap each other, the clockwise rotation and the counterclockwise rotation and the speed can be detected. Thus, the positions of both rotation ends can be detected as the reference position.
Here, since the first transmissive thin plate 83 and the second transmissive thin plate 84 are sandwiched between the transparent substrates 81 and 82 from both sides, the mechanical strength can be further increased while increasing the resolution.
In addition, the plate 80 to be detected is detachably attached to the support shaft 10i of the rear blade drive lever 60 and rotates integrally with the rear blade drive lever 60, so that the moment of inertia of the rear blade 40 is reduced. In addition, the rear blade 40 can be caused to perform a quick shutter operation, and the position of the rear blade 40 can be detected with high accuracy.

The optical sensor 90 is a light transmission type optical sensor including a light emitting element and a light receiving element, and sandwiches a plate 80 to be detected so as to rotate integrally with the rear blade drive lever 60 so as to face each other. It is fixed to the support plate 20.
The optical sensor 90 outputs a plurality of detection information in accordance with the amount of light passing through the detection plate 80.

Next, the operation of the focal plane shutter will be described with reference to FIG. 1, FIG. 2, and FIG.
First, in the rest state after the shutter operation is completed, as shown in FIG. 1, the leading blade drive lever 50 rotates clockwise by the biasing force of the biasing spring, and the drive pin 50a is provided at the end of the long hole 10b. The leading blade 30 is located at a position where the opening 10a is opened, and the trailing blade driving lever 60 is rotated clockwise by the biasing force of the biasing spring to drive the driving pin 60a. Stops in contact with a buffer rubber provided at the end of the long hole 10c, and the rear blade 40 is located at a position where the opening 10a is closed.
At this time, the detected plate 80 that rotates integrally with the rear blade drive lever 60 is in the state shown in FIG. 4A, and the rear blade 40 is positioned at the closed position (shutter operation completion position) by the optical sensor 90. Is being detected.

Here, when a shutter operation preparation command is issued by a release operation or the like, the set member (not shown) rotates clockwise, and the leading blade drive lever 50 rotates counterclockwise as shown in FIG. And set the position before the shutter operation (the front blade 30 closes the opening 10a) and rotate the rear blade drive lever 60 counterclockwise to set the position before the shutter operation (the rear blade 40 When the electromagnets 71 and 72 are energized, the attracted portions 50c and 60c are attracted to rotate the leading blade driving lever 50 and the trailing blade driving lever 60 clockwise. The set spring is held at the set position against the biasing force of the biasing spring. Then, the set member rotates counterclockwise, and the state of restricting the clockwise rotation of the leading blade driving lever 50 and the trailing blade driving lever 60 is released.
At this time, the detected plate 80 that rotates integrally with the rear blade drive lever 60 is in the state shown in FIG. 4B, and the rear blade 40 is opened by the optical sensor 90 (set position before the shutter operation). Although it is located in, it is detected.

  Subsequently, when the electromagnet 71 is de-energized at a desired timing, the leading blade drive lever 50 rotates clockwise by the biasing force of the biasing spring, and the leading blade 30 opens the opening 10a. When the energization of the electromagnet 72 is interrupted at a predetermined timing after the energization of the rear blade 40 is cut off, the rear blade drive lever 60 rotates clockwise by the biasing force of the biasing spring and the rear blade 40 closes the opening 10a. As shown in FIG. 1, the opening and closing operation of the opening 10a is performed by the leading blade 30 and the trailing blade 40, and the shutter operation is completed.

  According to the above-described embodiment, the light transmission plate in which the plate 80 to be detected is arranged so as to equally divide the slits 83a and 84a (bisect) in the plurality of slits 83a and 84a arranged in the circumferential direction. Since the portions 84b and 83b are provided, the resolution can be increased by the increase in the light transmission plate portions 83b and 84b as compared with the case of only the slit, and therefore the rear blade 40 can be controlled with high accuracy and high resolution. Therefore, the present invention can be preferably applied to an optical apparatus such as a digital video camera and a digital still camera that are required to be downsized while achieving simplification and downsizing of the structure.

8 to 10 show another embodiment of the plate to be detected included in the focal plane shutter according to the present invention.
In this embodiment, as shown in FIGS. 8A and 8B, the plate 180 to be detected is detachably attached to the support shaft 10i so as to rotate integrally with the rear blade drive lever 60.
As shown in FIGS. 9 and 10, the detection plate 180 includes a light-shielding base 181 formed in a substantially fan shape and a transmissive thin plate 182 laminated on the light-shielding substrate 181.

The light-shielding substrate 181 is formed of an opaque resin material or a metal plate or the like. As shown in FIGS. 9 and 10, the outer contour is formed in a substantially fan shape, and the fitting hole into which the support shaft 10i is fitted. 181a, a plurality of slits 181b that are formed to open radially at an interval of a predetermined angle 3θ / 2 around the axis S (of the support shaft 10i), and a light shielding plate portion 181c formed between the slits 181b and 181b. Etc.
Here, the circumferential width (angle) of the slit 181b is formed as an angle θ, and the circumferential width (angle) of the light shielding plate 181c between the slits 181b and 181b is formed as an angle θ / 2. .

The transmissive thin plate 182 is formed of a thin plate-like flexible substrate or a thin film material having a predetermined light transmittance. As shown in FIGS. 9 and 10, the outer contour is formed in a substantially fan shape, and the support shaft 10i. Fitting holes 182a, a plurality of slits 182b formed radially around the axis S (of the support shaft 10i) at an interval of a predetermined angle 3θ / 2, and slits 182b and 182b on one end side. A light transmission plate portion 182c formed between each other, a light transmission plate portion 182d formed between the slits 182b and 182b in other regions, and the like are provided.
Here, the circumferential width (angle) of the slit 182b is formed as an angle θ (excluding one end side), and the circumferential width (angle) of the light transmitting plate portion 182c is formed as an angle θ. The width (angle) in the circumferential direction of the light transmission plate portion 182d is formed as θ / 2.

As shown in FIG. 9, the light-shielding substrate 181 and the transmissive thin plate 182 are configured such that the other slits 181b and 182b are out of phase by an angle θ / 2, except for the slits 181b and 182b at both ends. Are stacked.
As a result, as shown in FIG. 9, the plate 180 to be detected has an angle θ / 2 following the opening 180a that forms the angle θ where the slits 181b and 182b (located at the clockwise rotation end) overlap. Three regions of the light shielding plate portion 180b, the light transmitting plate portion 180c having a predetermined light transmittance, and the opening portion 180d having an angle θ / 2 where the slits 181b and 182b overlap are repeated every angle 2θ, and the final angle θ The light transmitting plate portion 180e faces the slit 181b (located at the counterclockwise rotation end) following the light shielding plate portion 180b that forms a / 2.
Therefore, the reference value can be detected by detecting the opening 180a and the light transmitting plate 180e located at both ends, and the amount of light passing through the two regions (the light transmitting plate 180c and the opening 180d) is converted into light. By using a plurality of (two) threshold values that are detected by the sensor 90 and set based on the detection information, the resolution can be improved as compared with the case of only a slit.
Further, by reading the order of change from the light transmitting plate portion 180c to the opening portion 180d and the elapsed time, it is possible to detect the clockwise rotation or the counterclockwise rotation and the speed.
Here, since the light-transmitting substrate 181 has a structure in which the transmissive thin plate 182 is laminated, the resolution can be improved while ensuring the mechanical strength.
In addition, the plate 180 to be detected is detachably attached to the support shaft 10i of the rear blade drive lever 60 and rotates integrally with the rear blade drive lever 60, so that the moment of inertia of the rear blade 40 is reduced. In addition, the rear blade 40 can be caused to perform a quick shutter operation, and the position of the rear blade 40 can be detected with high accuracy.

11 to 13 show another embodiment of the focal plane shutter according to the present invention, except that a detection plate 80 is added to the frame 36 constituting the leading blade 30, as shown in FIG. The configuration is the same as that of the embodiment shown in FIG. 7. Therefore, the same reference numerals are given to the same configuration and the description is omitted, and the description is omitted because the shutter operation is also the same. .
In this embodiment, as shown in FIGS. 11 to 13, the plate 80 to be detected has two positions of the rear blade drive lever 60 and the arm 36 constituting the leading blade 30 as shown in FIGS. 11 and 12. The optical sensors 90 and 90 are arranged corresponding to the detected plates 80 and 80, respectively.

As shown in FIG. 13, the plate 80 to be detected is fixed so that it partially overlaps the end region of the arm 36 and is positioned by the positioning portion 36a.
The detected plate 80 attached to the arm 36 and the optical sensor 90 detect the position of the leading blade 30 when the position shown in FIG. 13A completes the shutter operation shown in FIG. Corresponding to the state, the position shown in FIG. 13B corresponds to the state of detecting the position of the leading blade 30 immediately before the shutter operation shown in FIG.
According to this embodiment, since the plate 80 to be detected is provided not only on the rear blade drive lever 60 but also on the arm 36 constituting the front blade 30, the structure is simplified and the size is reduced. The positions (or speeds) of the leading blade 30 and the trailing blade 40 can be detected with higher accuracy.

In the above embodiment, in the configuration provided with the leading blade 30 and the trailing blade 40, the configuration in which the detected plates 80 and 180 are integrally rotated with respect to the trailing blade driving lever 60 is shown. However, the present invention is not limited to this, and the detected plate may be provided so as to rotate integrally with the leading blade drive lever 50.
In the above-described embodiment, the detection plate 80 is provided on the arm 36 constituting the leading blade 30 and the detection plate 80 is provided on the trailing blade drive lever 60. However, the present invention is not limited to this. Conversely, the detected plates 80 and 180 may be provided on the leading blade driving lever 50, and the detected plates 80 and 180 may be provided on the arm 46 constituting the trailing blade 40.
Moreover, although the structure provided with the two blade members of the front blade 30 and the rear blade 40 was shown as a blade member, it is not limited to this, For example, it is equipped with one blade member, and only opens an opening part. The present invention can also be adopted in a configuration in which a shutter operation is performed by moving from a closed state to a closed state.

  As described above, the focal plane shutter according to the present invention can increase the resolution of the detected member detected by the optical sensor while achieving simplification and downsizing of the structure. In addition to being applicable to digital video cameras, digital still cameras, and the like that require control, downsizing, etc., they are also useful in other optical devices.

10 ground plane 10a opening 10i support shaft 30 leading blade (blade member)
36a Positioning part 40 Rear blade (blade member)
50 Leading blade drive lever (drive member)
60 Rear blade drive lever (drive member)
60a Drive pin 60e Positioning portion 71, 72 Electromagnet 80 Detected plate 80a, 80b, 80c Light transmitting plate portion 80d Opening portion 81, 82 Transparent substrate 81a, 82a Fitting hole 81b, 82b Positioning hole 81c, 82c Transparent flat plate portion 83 1 transmissive thin plate 83a slit 83b light transmissive plate portion 83c fitting hole 84 second transmissive thin plate 84a slit 84b light transmissive plate portion 84c fitting hole 90 optical sensor 180 detected plate 180a opening 180b light shielding plate portion 180c light transmissive plate Portion 180d opening 180e light transmission plate portion 181 light shielding substrate 181a fitting hole 181b slit 181c light shielding plate portion 182 light transmission thin plate 182a fitting hole 182b slit 182c, 182d light transmission plate portion

Claims (7)

A ground plate having an opening for exposure; a blade member movably provided on the ground plate to open and close the opening; a drive member for driving the blade member; and a substrate moved in conjunction with the blade member. A focal plane shutter comprising: a detection plate; and an optical sensor disposed to face the detection plate,
The detected plate includes a plurality of slits formed by opening radially at a predetermined angle interval, and predetermined slits respectively disposed in the plurality of slits so as to equally divide the plurality of slits in the circumferential direction. Having a light transmissive plate portion having light transmittance,
A focal plane shutter characterized by that. The plate to be detected has a light-shielding substrate having a plurality of slits that are radially opened at intervals of a predetermined angle, and has a plurality of slits that are radially opened at intervals of a predetermined angle, and the light-shielding plate. Including a transparent thin plate having a predetermined light transmittance laminated on a conductive substrate,
The focal plane shutter according to claim 1. The plate to be detected has a plurality of slits formed to be radially opened at intervals of a predetermined angle and has a first transmissive thin plate having a first light transmittance, and is radially opened at intervals of a predetermined angle. A second transmissive thin plate having a plurality of slits formed and having a second light transmittance laminated on the first transmissive thin plate by shifting the phase of each slit; and the first transmissive thin plate And a transparent substrate on which the second transmissive thin plate is laminated,
The focal plane shutter according to claim 1. The transparent substrate includes a pair of transparent substrates that sandwich the first transparent thin plate and the second transparent thin plate,
The focal plane shutter according to claim 3. Including a support shaft that rotatably supports the drive member around a predetermined axis,
The detected plate is detachably attached to the support shaft so as to rotate integrally with the drive member.
The focal plane shutter according to claim 1, wherein the focal plane shutter is a shutter. The blade member includes a plurality of blade main bodies and a plurality of arms connecting the plurality of blade main bodies,
The detected plate is attached so as to rotate integrally with the arm.
The focal plane shutter according to any one of claims 1 to 5, wherein The focal plane shutter according to claim 1 is provided.
A camera characterized by that.

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