JPH0442821Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of application of the invention] This invention relates to an electric exposure device that can electronically control the aperture device of a camera, and in particular, an electric exposure device that is integrated with a camera lens barrel or an interchangeable lens. The present invention relates to an electric exposure apparatus with a novel structure.

[Background of the idea]

A 35mm camera with a non-interchangeable lens is generally referred to as a compact camera, and this type of camera is equipped with a lens shutter device that serves as an exposure device and serves as both a shutter and an aperture. The lens shutter device mounted on a compact camera has a direct electromagnetic drive structure, and examples of lens shutter devices with such a direct electromagnetic drive structure include the one disclosed in Japanese Patent Application Laid-Open No. 1983-1999.
Some of these are disclosed in Publication No. 37745, etc.

In this known lens shutter device with a direct electromagnetic drive structure, the annular disk itself (or an annular disk of the same shape connected to the annular disk) carrying the shutter blades (i.e., aperture blades)
constitutes the rotor of the electromagnetic drive device (i.e. motor), there is no need to provide a mechanical mechanism within the camera body for rotating and positioning the annular disk, and therefore the exposure device in a compact camera (that is, the shutter and diaphragm device) are very small and lightweight, and have a structure suitable for electronic control. Also, although it has not been put to practical use, a cylindrical (or ring-shaped) rotor with a ring-shaped rotor of about the same diameter as the lens barrel is also available.
A lens shutter device in which a sector ring is rotated by a stepping motor has also been proposed (see, for example, Japanese Patent Laid-Open No. 17428/1983). In these known lens shutter devices, the sector ring carrying the aperture blades (sectors) is driven by a motor directly coupled to it, so that the sector ring can be rotated and positioned by any desired angle. It does not require a complicated mechanical mechanism, is therefore small and lightweight, and is suitable for electronic control.

On the other hand, single-lens reflex cameras (hereinafter abbreviated as single-lens reflex cameras) are equipped with larger-diameter lenses than compact cameras and are interchangeable. The barrel (that is, the interchangeable lens) is equipped with an aperture device, and the aperture device is configured to be mechanically driven via an interlocking lever from an aperture drive device provided inside the camera body. has been done. In conventional single-lens reflex cameras with such a structure, not only is the mechanical structure of the aperture drive device inside the camera body complicated, but also the mechanical structure inside the lens barrel related to the aperture device, including the interlocking lever, is complicated. Due to the complicated structure of the camera, the weight of the entire camera including the lens barrel is heavy, and the volume of the entire camera is also large. Further, since power is transmitted to the throttle device via a complicated mechanical power transmission mechanism, the responsiveness of the control operation is poor and it is unsuitable for electronic control.

Therefore, in conventional single-lens reflex cameras, it has been necessary to reduce the overall weight of the camera by improving the aperture device, and to realize an aperture device that operates at high speed and has good control response.

In order to reduce the weight and volume of the camera body and interchangeable lenses, as well as to realize an aperture device that operates at high speed and has good control response, the aperture device for single-lens reflex cameras is a direct electric type, similar to that for compact cameras. Preferably, it is constructed as a diaphragm device.

However, conventionally, the electromagnetic drive device of the lens shutter equipped in a compact camera is the annular disk itself (or an annular disk of the same diameter that is integrated with the annular disk) that carries the aperture blades, as described above. is the rotor, so the inertia of the rotor ^itself is very large. (The inertial mass of the rotor of the electromagnetic drive device is very large.) Therefore, the starting performance and control response are poor, and furthermore, the stator coil has the same effective diameter as the annular disk. Since it is a circular coil, it is not possible to increase the number of turns, so a high ampere turn cannot be obtained, and therefore only a small starting torque can be obtained. Therefore, although it is practical as an aperture drive motor for a small-diameter lens such as a compact camera, it is impossible to use the structure of the electromagnetic drive device as a motor for a large-diameter aperture device for a single-lens reflex camera. It was hot. In other words, if a motor for a large-diameter diaphragm device with the same structure as the electromagnetic drive device is designed, it is difficult to start the rotor because the magnetomotive force cannot be increased even though the inertial mass of the rotor is extremely large. This becomes difficult, and step-out easily occurs, causing the rotor to frequently remain in a state where it vibrates at the stop position and does not rotate.

Therefore, it has been found that an electric aperture device for a large-diameter lens cannot be realized with an aperture device having the same structure as a lens shutter device installed in a conventional compact camera.

[Purpose of invention]

The purpose of this invention is to provide an electric exposure device that does not increase the outer diameter when attached to a lens barrel having a large-diameter lens, and that can prevent unauthorized reflections caused by the parts of the motor used. It's about doing.

[Summary of the idea]

The electric exposure apparatus of this invention includes a rotating member that supports a plurality of light shielding blades and changes the opening amount of an optical path hole by rotating the light shielding blades, and a rotary member that rotates the rotary member. The drive source is a rotor having a rotor axis parallel to the optical axis, a stator disposed facing each other so as to sandwich the rotor, and having a plurality of fork-shaped pole teeth formed parallel to the optical axis, and a light beam. A motor consisting of a coil arranged parallel to an axis, the rotor, the stator, and the coil arranged in a substantially arc shape near the periphery of the optical path hole; and a motor that supports at least the stator of the motor. and a support member having a light-shielding tube portion concentric with the optical path hole formed in a region on the inner diameter side of the stator and the coil so as to overlap with the stator and the coil in a direction perpendicular to the optical axis. shall be.

[Example of idea]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view of essential parts of an electric exposure apparatus according to the present invention.

The electric exposure apparatus of the present invention is composed of an exposure apparatus main body part, a motor part, and a motor support plate and light shielding member configured as a part of a lens barrel of a camera or a part of an interchangeable lens. ing.

The main body of the exposure apparatus includes an annular disk-shaped rotating ring 17 having an optical path hole 17g in the center, and a plurality of aperture blades (shading blades) 16 that are pivotally mounted to the rotating ring 17 to open and close the optical path hole 17g. and the rotating ring 1
7 rotatably supported and the aperture blade 16
an annular disk-shaped cam plate 15 that guides the rotary ring 17 along a predetermined path; and an annular disk-shaped support member 1 that prevents the rotation ring 17 from moving in the axial direction and also serves as a support plate for a motor to be described later. , is composed of.

An optical path hole 17g is formed in the center of the rotating ring 17, and a plurality of pin holes 17a are formed outside the optical path hole into which pins 16b protruding from the aperture blade 16 are inserted. A gear portion 17c that meshes with a pinion 4, which will be described later, is formed on the surface. Further, a protrusion 17b is formed on the outer peripheral surface of the rotary ring 17, and the protrusion 17b constitutes a rotation angle limiting means for limiting the rotation angle of the rotary ring 17 together with the protrusion of the cam plate 15, which will be described later. ing.

The support member 1 is disposed facing one end surface of the rotating ring 17 (the end surface on which the aperture blades 16 are not disposed), and is fixed to a structural member (not shown). The support member is formed to have a larger external dimension than the rotating ring 17, and has an optical path hole 1a having the same diameter as the optical path hole 17g of the rotating ring 17 in the center. Around the optical path hole 1a of the support member 1, a bearing 1 rotatably supports a rotor shaft of a motor to be described later.
b, two holes 1c and 1d for fitting and fixing the iron core of the stator coil of the motor, four screw holes 1e for fastening the cam plate 15, and a motor support plate and light shielding plate to be described later. Pin insertion holes 1g and 1h for connecting members and a long hole 1f for attaching a conductive pattern plate 14 (described later) are formed.

The cam plate 15 is arranged to face the aperture blade mounting surface of the rotary ring 17 and is fastened to the support member 1. The cam plate 15 is connected to the optical path hole.
17g and an optical path hole 15i having the same diameter as that of the support member 1.
The flat protrusions 15b to 15e are provided.
These protrusions 15b to 15e are all formed to have the same protrusion height, and the inner circumferential surface of the protrusion 15b fits into the smooth cylindrical surface 17h of the rotating ring 17, and the inner circumferential surfaces of the other protrusions are It fits into a smooth cylindrical surface 17i formed on the outer periphery of the rotating ring 17, and the rotating ring 17 is rotatably supported by the cam plate 15 by the protrusion. Each of the protrusions 15b to 15e has a long hole 15f extending in the circumferential direction, and when the cam plate 15 is fastened to the support member 1, the long hole 15f
The cam plate is fixed to the support member 1 by inserting a fastening screw 3 into the screw hole 1e and screwing the screw 3 into the screw hole 1e. Since the long hole 15f is formed in the cam plate 15, when fastening the cam plate 15 to the support member 1, the fixed position of the cam plate 15 is adjusted by rotating the cam plate 15 in the circumferential direction. be able to. By this fixed position adjustment operation, the initial rotational position of the rotary ring 17 and the relationship between the aperture blade 16 and the cam groove 15a are adjusted.

When the cam plate 15 is fastened to the support member 1, the rotary ring 17 uses two smooth cylindrical surfaces 17h and 17i on its outer circumferential surface to engage the protrusions 15b to 1 of the cam plate 15.
5e, while the left end surface of the rotating ring 17 (i.e., the aperture blade 1
6 is not disposed) is brought into contact with the right end surface of the support member 1, and the rotary ring 17 is supported by the support member 1 so as not to move in the axial direction.

Further, when the cam plate 15 and the support member 1 are fastened together as described above, each aperture blade 16 pivotally attached to the rotating ring 17 via the pin 16b is attached to the cam plate 15.
A pin 16a protruding from the aperture blade 16 is inserted into the cam groove 15a, facing the cam groove 15a formed in the cam groove 15a.

Support member 1, cam plate 15, and rotating ring 1
7 is assembled, the protrusion 15b of the cam plate 15 is positioned between the protrusion 17b and the tooth 17c of the rotary ring 17. Therefore, rotating ring 1
When 7 is rotated clockwise in Fig. 1, the tooth 1
When one end 17f of 7c comes into contact with one end surface 15g of the protrusion 15b, the clockwise rotation of the rotary ring 17 is prevented, and when the rotary ring 17 is rotated counterclockwise, one of the protrusions 17b end face 1 of
When the ring 7e comes into contact with the other end surface 15h of the protrusion 15b, the rotation of the rotating ring 17 in the counterclockwise direction is prevented. That is, the protrusion 15b of the cam plate 15, the protrusion 17b of the rotary ring 17, and one end 17f of the toothed portion 17c are configured as a stopper for restricting the rotation of the rotary ring 17 within a certain rotation angle range. .

Further, the protrusions 15b to 15e are formed on the cam plate 15.
It also serves as a spacer for forming a space for accommodating the rotary ring 17 and the aperture blade 16 between the rotary ring 17 and the support member 1, and by forming the protrusions 15b to 15e, the rotary ring 17 and the aperture blade 16
and is protected from external forces in the axial direction.

A sliding contact piece 17d, which together with a conductive pattern plate 14 (described later) constitutes a sliding contact type detector, is attached to the protrusion 17b of the rotating ring 17.
Correspondingly, a conductive pattern plate 14 having a conductive pattern 14a in sliding contact with the sliding contact piece 17d is fastened to the surface of the support member 1 facing the rotating ring with screws 14c. Since the screws 14c are inserted into the long holes 1f of the support member 1, when attaching the conductive pattern plate 14 to the support member 1, the conductive pattern plate 14 can be adjusted and positioned in the circumferential direction of the support member 1. . (Adjustment of the mounting position of the conductive pattern plate 14 is necessary to adjust the contact position between the sliding contact piece 17d and the conductive pattern plate 14a.) The sliding contact piece 17d and the conductive pattern 14a are of a sliding contact type. The detector constitutes an aperture state detection device that detects the aperture state of the optical path hole 17g (the position of the aperture blade 16) by detecting the rotational position (rotation angle) of the rotating ring 17. constitutes a means.

The conductive pattern 14a is connected to a detection circuit (not shown) via a lead wire 14b, and is activated in the detection circuit in response to on/off signals generated by contact and non-contact between the sliding contact piece 17d and the conductive pattern 14a. Detection of the open hole state is performed electrically.

In the case of this embodiment, when the contact piece 17d is in contact with the conductive pattern 14a, it is in a small aperture state,
The aperture is configured to be in an open state when the contact piece 17d and the conductive pattern 14a are not in contact with each other. The detection means is for determining whether the aperture is opened or not, and for example,
It forms part of a safety system that prohibits photometry (that is, prohibits photography) when the aperture blades move toward a smaller aperture due to an external impact or the like.

Next, the structure of the motor portion and the motor support plate and light shielding member in the electric exposure apparatus of the present invention will be explained.

The motor built into the device of the present invention is a two-phase stepping motor, and has the following structure.

The motor includes a cylindrical (or cylindrical) rotor 2 having a smaller diameter than the radius difference between the inner and outer circumferential surfaces of the support member 1, and a stator disposed close to the outer circumferential surface of the rotor 2. 6 to 9, stator coils 12 and 13 disposed close to the outside of the stators 6 to 9, and iron cores 10 and 11 of the stator coils. The shafts 2a and 2b of the rotor 2, the pole teeth 6a to 9a of the stators 6 to 9, and the stator coils 12 and 1
3 is formed to be parallel to the optical axis, and is arranged in an arc shape along the periphery of the optical path hole 1a of the support member 1, and the motor is arranged in a partially annular shape that curves along the periphery of the optical path hole 1a. It is formed.

One end of the motor is supported by a support member 1, and the other end of the motor is supported by a motor support plate/shading member 5 spaced in front of the support member 1.

The motor support plate/light shielding member 5 is a constituent member of a lens barrel of a single-lens reflex camera or a constituent member of a lens barrel of an interchangeable lens. It has a cylindrical part having an optical path hole with a diameter equal to , and a light shielding part/motor support part integrally formed above the cylindrical part. The light shielding part and motor support part has a cylindrical surface having an outer diameter equal to the outer diameter of the support member 1 on the upper part and has a shape that widens laterally, and the shaft 2a of the rotor 2 of the motor is supported in this part. a bearing 5a for fixing and positioning the stator 7; and a pin 5 for fixing and positioning the stator 7.
b, and a pin 5c for fixing and positioning the stator 9. Note that the bearing 5a
Eight square holes 5d arranged in an arc shape with
have teeth 7a of stator 7 and stator 9, respectively.
tooth 9a is inserted.

The rotor 2 is constructed as a cylindrical body with an outer diameter smaller than the difference between the inner and outer radii of the support member 1, and the motor is therefore more compact than known motors for lens shutters having an annular rotor. It has an extremely small GD ² value, resulting in a motor with excellent starting performance and control response.

The rotor 2 is a cylindrical body made of permanent magnets, and its outer peripheral surface has an N pole piece parallel to the axial direction and an S pole piece parallel to the axial direction.
The pole pieces are arranged alternately in the circumferential direction, and the circumferential length of each north pole piece and each south pole piece is approximately equal to the circumferential length of the teeth 6a to 9a of the stators 6 to 9. In this embodiment, the number of N poles and S poles on the outer circumferential surface of the rotor 2 is 11. That is, the outer circumferential surface of the rotor 2 is composed of 11 N pole pieces and 11 S pole pieces arranged alternately. ing.

The teeth 6a of the stator 6 and the teeth 7a of the stator 7 are alternately arranged along the outer peripheral surface of the rotor 2, as shown in FIG.
Similarly, the teeth 9a of the stator 9 and the teeth 9a of the stator 9 are alternately arranged along the outer peripheral surface of the rotor 2. The width l of the inner end surface of each stator tooth (the circumferential length l on the surface facing the outer circumferential surface of the rotor 2) is approximately equal to the circumferential length of each pole piece of the rotor 2 facing it, and therefore the stator The teeth of the rotor 2 and the magnetic pole pieces of the rotor 2 are arranged to directly face each other. However, in this embodiment, as shown in FIG.
The teeth 8a and 9a are arranged at an intermediate position between the north pole piece and the south pole piece of the rotor 2.

A cylindrical stator coil 12 wound around an iron core 10 is disposed outside the stator teeth 6a and 7a arranged in an arc shape along the outer peripheral surface of one half of the rotor 2.
A cylindrical stator coil 13 wound around an iron core 11 is arranged outside the stator teeth 8a and 9a arranged in an arc along the outer peripheral surface of the other half of the rotor 2. Each of the stators 6 to 9 has holes 6b to 9b through which the respective iron cores 10 and 11 are fitted and fixed, and the iron core 10 is fitted into the holes 6b and 7b and integrated with the stators 6 and 7, The iron core 11 is fitted into the holes 8b and 9b and integrated with the stators 8 and 9. Further, one ends of the iron cores 10 and 11 are fitted into the holes 1d and 1c of the support member 1, respectively, and one end side of the iron core 10 and the stators 6 and 7, and one end side of the iron core 11 and the stators 8 and 9 are respectively inserted into the support member 1. is fixed to and supported by the support member 1.

One shaft 2b of the rotor 2 is rotatably supported in a bearing 1b provided on the support member 1, and projects toward the rotating ring 17 through the bearing 1b, and is connected to the shaft 2b at the projecting end. A fixed pinion 4 is engaged with a rotating ring 17.

Pin insertion holes 7c and 9c are formed in the stators 7 and 9 at positions that are aligned with pins 5b and 5c provided in the motor support plate and light shielding member 5, and when the device of the present invention is assembled, the pin insertion holes 7c and 9c are formed as motor support plates and light shielding members. Insert the pin b of the light shielding member 5 into the pin insertion hole 7 of the stator 7.
At the same time, the pin 5c is inserted into the pin insertion hole 9c of the stator 9, and the stators 7 and 9 are supported by the motor support plate and light shielding member 5.

On the other hand, the stator 6 is formed with a hole 6c that is aligned with the hole 1g of the support member 1 and has the same diameter as the hole 1g, and the stator 8 is formed with a hole 6c that is aligned with the hole 1h of the support member 1 and has the same diameter as the hole 1g. A hole 8c with a diameter of The stators 6 and 8 are supported by the support member 1, and when attaching the stators 6 and 8 to the support member 1, the holes 1g and 6c are aligned and a motor support plate/shading member 5 is inserted into both holes. While fixing the stator 6 to the support member 1 by driving pins (not shown) provided on the back surface of the motor supporting plate and light shielding member 5, aligning the holes 1h and 8c, The stator 8 is fixed to the support member 1 by driving in a pin (not shown).

FIG. 2 is a diagram for explaining the relative positional relationship between the rotor 2 and the stators 6 to 9 and the rotation indexing operation of the rotor 2.

In addition, FIG. 3 corresponds to FIG.
9 is a chart explaining the excitation state of No. 9.

FIG. 2a shows the relative positional relationship between the rotor 2 and the stators 6 to 9 when the coils 12 and 13 are not energized. Directly facing each tooth 6a,
Further, the N pole piece of the rotor 2 is connected to each tooth 7a of the stator 7.
The rotor 2 is stationary in a state facing directly. On the other hand, at this time, each of the teeth 8a and 9a of the stator 8 and the stator 9 is directly opposed by half of the S pole piece and the half of the N pole piece of the rotor 2. In this case, stator 7
stator 8 at the endmost tooth and the stator 8 at the position closest to the tooth.
The angle θ between the teeth is expressed as θ=np+1/2P. (However, P is the pitch between adjacent teeth of stators 6 and 7, and the pitch between adjacent teeth of stators 8 and 9.) The rotor 2, which is stopped in the state shown in FIG. Coil 1 to rotate by angle
The energization time (or number of control pulses) and energization direction for 2 and 13 are controlled, for example, as shown in FIG.

FIG. 3 shows the energization direction and energization time for the coils 12 and 13, where the horizontal axis shows the energization time (or number of pulses) and the vertical axis shows the on/off state. Further, as shown in FIGS. 2b to 2d, A indicates energization in the positive direction to the coil 13, B indicates energization in the reverse direction to the coil 13, B indicates energization in the positive direction to the coil 12, and
2 respectively represent the reverse direction of energization.

A method for controlling the rotation of the rotor 2 will be described below with reference to FIGS. 2b to 2d and FIG. 3.

When the coil 13 is energized A and the coil 12 is energized as shown in FIGS. 2b and 3, the teeth 6a of the stator 6 become N, the teeth 7a of the stator 7 become S,
The teeth 8a of the stator 8 are magnetized to N, and the teeth 9a of the stator 9 are magnetized to S. For this reason,
Each tooth of each stator 6 to 9 and the magnetic pole pieces on the outer circumferential surface of the rotor 2 attract or repel each other, and the rotor 2
The rotor rotates counterclockwise by 4P, but when it rotates by 1/4P, the forces exerted on the rotor 2 by the stators 6 and 7 and the forces exerted on the rotor 2 by the stators 8 and 9 are equal and in opposite directions. 2 stops. At this time, as shown in Figure 3, the coil 1
When only the current to stator 2 is cut off, stator 6
and 7 are demagnetized, and only the energized state of stators 8 and 9 continues as shown in FIG. 2c. Therefore, the rotor 2, which had stopped at a position shifted by 1/4P with respect to each tooth of the stators 6 and 7, until its N pole piece directly faces the tooth 9a of the stator 9 (which is magnetized to S). After rotating counterclockwise, it will stop again. The rotation angle of the rotor 2 in this case is also 1/4P.

Next, as shown in FIG. 2d, when the coils 12 and 13 are energized B and A, respectively, the stator 6
The teeth 6a of the stator 7 are excited to S, the teeth 7a of the stator 7 are excited to N, and the teeth 8a of the stator 8 are excited to N.
Also, since the teeth 9a of the stator 9 are excited to S, the rotor 2 is excited by the same principle as above.
rotates counterclockwise by 1/4P and then stops.

As shown in FIG. 2, the number of combinations of current direction to the coils 12 and 13 is as follows:
There are 5 ways of A, , and 8 ways of energization in total. In the apparatus of this embodiment, the rotor 2 is rotated in steps by pulse-controlling the energization of the coils 12 and 13, with each of the energization methods described above as one pulse.

In the case of this embodiment, the shape of the cam groove 15a and the rotation angle of the rotary ring 17 are determined so that the aperture diameter changes by 1/8 step when the rotor 2 rotates one step. That is, in the case of this embodiment, the relationship between the cam groove 15a and the rotation angle of the rotary ring 17 is determined so that the aperture changes by one step when the rotor 2 rotates eight steps.

FIG. 4 is a longitudinal sectional view of an interchangeable lens integrally formed with the electric exposure apparatus of the present invention. In the figure, reference numeral 5 denotes the aforementioned motor support plate and light shielding member which is a structural member of the interchangeable lens, and the presence of the motor support plate and light shielding member 5 prevents light from flowing in the direction of arrow F. Entry is blocked.

Teeth 6a of the stators 6 to 9 that easily reflect light
9a and the coils 12 and 13 are arranged parallel to the optical axis in order to be arranged in a circular arc, which increases the possibility that the light guided into the interchangeable lens will be incorrectly reflected. In this embodiment, the cylindrical portion of the motor support plate and light shielding member 5 is formed so as to overlap in the inner diameter side region of the stators 6 to 9 and the coils 12 and 13 in the direction perpendicular to the optical axis.
Unauthorized reflection of light can be prevented. ,or,
The cylindrical part does not shield only the inner diameter area of the motor structure, but is made into a light-shielding cylindrical part concentric with the optical path hole, so that it is possible to prevent stray light throughout the donut-shaped space caused by the arrangement of the motor structure. can.
In addition, the square holes 5d provided in the motor support plate and light shielding member 5 can accurately position the tips of the teeth 6a and 8a of the stators 6 and 8, and even if the stator teeth 6a to 9a are formed long in parallel with the optical axis, the motor Performance can be improved.

In FIG. 4, 2 is a rotor, 18 is an autofocus motor, 19 is a lens mount, and 20 is a connection terminal for connecting the power supply and electronic circuit inside the camera body to the electronic circuit inside the interchangeable lens. , L ₁ to L ₆ are lenses. Further, the upper half of FIG. 4 shows the zoomed state, and the lower half of FIG. 4 shows the non-zoomed state.

Next, a case will be described in which an interchangeable lens having a built-in electric exposure device as described above is attached to a camera with an AE (automatic exposure control device) to take pictures.

FIG. 5 is a block diagram showing a part of the control system of a camera having an electronically controlled aperture device as described above.

In FIG. 5, 21 is a photometry circuit, 22 is a light amount setting circuit, 23 is a shutter drive circuit, 24 is a clock pulse generation circuit, 25 is a distribution circuit, and 26 is a motor control circuit for controlling the motor.

Next, the control operation and the operation of the aperture blades 16 when photographing with the camera will be explained with reference to FIGS. 1 and 5.

When you press the camera release button when taking a picture, the photometry circuit 21 operates and automatically measures the light. Based on the resulting photometry value, the light amount setting circuit 22 sets the film sensitivity, required shutter speed, and required aperture. The required number of aperture stages is determined by calculation from the values and the like. The number of aperture stages determined by the light amount setting circuit 22 is input to the distribution circuit 25 and
Then, the clock pulse generated by the clock pulse generating circuit 24 is divided into a predetermined number of steps and applied to the motor control circuit 26. Motor control circuit 26
In this case, the direction of current flowing through the coils 12 and 13 and which coil is energized are controlled according to input signals, and as a result, the rotor 2 is rotated by a predetermined angle in a predetermined direction. (The control of the rotation of the rotor 2 has already been explained, so the explanation will be omitted.) Therefore, the rotating ring 17 is rotated via the pinion 4, and the aperture blades 16, which are pivotally connected to the ring 17, are rotated together with the ring 17. 17 while rotating around its own pin 16b.
It is oscillated along the cam groove 15a around the cam groove 15a.
When the aperture blades 16 are rotated clockwise around the pin 16b in FIG. 1, the aperture is opened, and when the pin 16a reaches the outermost position of the cam groove 15a, the aperture becomes open. . The opening of the aperture is detected by a switch composed of a sliding contact piece 17d and a conductive pattern plate 14.
The information is electrically stored and the next control operation is performed by an electronic circuit (not shown).

The features of the electric exposure apparatus of this embodiment described above are listed as follows.

() Since the rotor of the motor has a small diameter with dimensions close to the difference between the inner and outer radii of the rotating ring, the rotor's GD ²
Therefore, the motor has excellent startability and call response.

() The support member 1, which is a structural member of the main body of the exposure device, also serves as a support member for the motor, and since the motor and the main body of the exposure device are integrated, the electric exposure device is small and lightweight. .

() Compared to the electromagnetic drive means of conventional lens shutter devices, the motor of the device of the present invention has a smaller rotor diameter, a larger number of turns of the stator coil, and a larger cross-sectional area of the iron core for the coil, which results in less magnetic saturation. Therefore, an electric exposure apparatus equipped with a motor having a large starting torque and good high-speed response can be obtained.

() Since the motor support plate and light shielding member that supports one end of the motor is configured as a part of the lens barrel of the interchangeable lens or camera, the interchangeable lens or camera incorporating the device of the present invention can be made lightweight and compact. In addition, the interchangeable lens and the aperture of the camera can be electronically controlled.

[Effect of idea]

The electric exposure apparatus of the present invention has the motor arranged in a substantially arc shape near the periphery of the optical path hole, so it can be made smaller and the outer diameter can be reduced. To solve the problem of irregular reflection of stray light due to the teeth and coils being parallel to the optical axis, a light shielding member was formed on the stator support member so that it was concentric with the optical path hole and overlapped in the direction orthogonal to the optical axis of the stator and coil. It was resolved by this.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of essential parts of an embodiment of an electric exposure apparatus according to the present invention, and FIG. 2 a, b, c,
d is a diagram for explaining the arrangement of the rotor and stator of the motor built in the device of FIG. 1 and the operation of the motor, and FIG. 3 shows the control signal applied to the stator of the motor of FIG. 2. 4 is a vertical cross-sectional view of an interchangeable lens formed integrally with the device of FIG. 1, and FIG. 5 is a block diagram showing part of the control system of a camera incorporating the device of the present invention. 1...Support member, 2...Rotor, 4...Pinion, 5...Motor support plate and light shielding member, 6-9...
Stator, 10... Iron core, 11... Iron core, 12...
... Coil, 13 ... Coil, 14 ... Conductive pattern plate, 15 ... Cam plate, 16 ... Aperture blade, 17
...Rotating ring.

Claims (1)

[Claims for Utility Model Registration] A rotary member that supports a plurality of light shielding blades and rotates to move the light shielding blades and change the opening amount of an optical path hole; and rotating the rotary member. A rotor having a rotor axis parallel to the optical axis, a stator disposed opposite to each other so as to sandwich the rotor, and having a plurality of fork-shaped pole teeth formed parallel to the optical axis, and an optical axis. a motor comprising a coil arranged in parallel with the rotor, the stator, and the coil arranged in a substantially arc shape near the periphery of the optical path hole; and a motor supporting at least the stator of the motor. The support member further includes a support member formed with a light-shielding cylinder portion concentric with the optical path hole in a region on the inner diameter side of the stator and the coil so as to overlap with the stator and the coil in a direction perpendicular to the optical axis. Electric exposure equipment.