JPH10319294A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize appropriate exposure even when the opening amount of a diaphragm is changed at the time of shift and tilt operation or at the time of zoom operation by correcting the driving amount of a diaphragm mechanism by a driving device based on the detected result by a detecting device. SOLUTION: A shift amount and a tilt amount are detected by a shift amount detecting device 18 and a tilt amount detecting device 19 and the detected result is transmitted to a rotational angle processing circuit 14. The storage device of the circuit 14 calculates the correction driving amount of a diaphragm blade 17 corresponding to the rotational angle of an interlocked disk member 10 and corresponding to the shift amount and the tilt amount based on the corresponding data of the correction amount of the driving amount of the blade 17 with respect to the shift amount and the tilt amount. An electromagnetic diaphragm driving control circuit 15 transmits a necessary driving instruction to an electromagnetic diaphragm unit 16 based on the value of the correction driving amount transmitted from the circuit 14. The unit 16 drives the blade 17 by the correction driving amount by using a motor in the unit so as to change the opening amount D formed by the blade 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel which is interchangeable with a camera body and has an aperture mechanism.

[0002]

2. Description of the Related Art When a lens barrel of a camera is replaceable with respect to a camera body and an aperture of an aperture is determined in accordance with the brightness of a subject, conventionally, an aperture mechanism interlocking lever on the lens barrel side and a camera are conventionally used. 2. Description of the Related Art There is generally known a mechanism in which an aperture setting lever on a main body side is mechanically interlocked to change an aperture amount of an aperture in a lens barrel in conjunction with an amount of movement of the aperture setting lever. In this mechanism, a method of controlling the aperture of the lens barrel by controlling the position of an aperture setting lever based on an exposure result measured on the camera body side or an aperture value set by a user is known.

An example of such a conventional aperture mechanism will be described with reference to FIG. An aperture mechanism interlocking lever 201 is rotatably supported on a rotation shaft 202 fixed to a lens barrel (not shown). The lever interlocking pin 203 fixed to the aperture blade drive plate 204 is
Is engaged with the groove 201a at the tip end of the head. The aperture blade driving plate 204 is rotatably supported with respect to the lens barrel.

The spring 206 has one end fixed to the diaphragm blade driving plate 204 and the other end fixed to the lens barrel. The elastic force of the spring 206 acts in the direction of the arrow F shown in the figure, and the diaphragm blade drive plate 204 is urged by the elastic force in the direction of the arrow Y3 shown in the figure to be rotatable.
The aperture blade driving plate 204 is provided with a plurality of cam grooves 207 (only one groove is shown in the figure). The fixed disk 211 is fixed to the lens barrel. The fixed disk 211 has a plurality of holes 212 for rotatably supporting the aperture blade 209 (only one hole is shown in the figure). The aperture blade 209 has a pin 208 for engaging with the cam groove 207.
And a pin 2 for fitting into the hole 212 of the fixed disk 211
10 are provided. The aperture setting lever A is provided on the camera body (not shown), and the aperture mechanism interlocking lever 201 presses the aperture setting lever A by the elastic force of the spring 206.

When the aperture setting lever A moves in the direction of the arrow Y1 shown in the drawing, the aperture mechanism interlocking lever 210 rotates about the rotary shaft 202 without separating from the aperture setting lever A by the elastic force of the spring 206, and the groove 201a. Moves in the direction of arrow Y2 shown in the figure. Accordingly, the lever interlocking pin 203 moves by an amount equivalent to the amount of movement of the groove 201a,
The aperture blade driving plate 204 rotates about the center of the aperture blade driving plate 204 as the rotation center in the direction of the arrow Y3 shown in the figure by the movement amount of the groove 201a. As a result, the position of the cam groove 207 changes, and the aperture blade 209 is rotated by the pin 208 engaged with the cam groove 207 in the direction of reducing the aperture amount in the arrow Y4 direction shown in the drawing. Thus, the aperture blade 20
Since the rotation amount of the stop 9 can be controlled by the movement amount y of the aperture setting lever A, the opening amount of the stop can be controlled by the movement amount y of the aperture setting lever A.

However, according to the conventional aperture mechanism shown in FIG. 3, for example, in a lens barrel which performs shift and tilt during tilt photographing, the aperture mechanism section 20 shown by a broken line in FIG.
Since the entire lens 0 shifts and tilts with respect to the camera main body, it becomes impossible to interlock the aperture setting lever A on the camera main body side with the lever interlocking pin 203 by the aperture mechanism interlocking lever 201.

As described above, when the optical axis of the photographing optical system is shifted and tilted with respect to the image plane as in tilt shooting, the aperture interlocking mechanism is used to shift and tilt the lens barrel together with the photographing optical system. Incorporation into the device causes the mechanism itself to be complicated, and the precision of each component must be strict, and it is very difficult to realize, and the cost is high. The same applies to a case where the aperture amount of the lens barrel that can be zoomed is changed with respect to the same aperture value during zooming.

Also, information such as an exposure result measured by the camera body and an aperture value set by a user are electrically transmitted to the lens side, and the aperture mechanism is driven by a desired amount by an electromagnetic force or the like, so that the aperture is controlled. A method of controlling the opening amount is known. According to this method, since there is no mechanical interlock between the camera body and the lens barrel, even in the above-described type of lens barrel, the control of the aperture opening amount from the camera body is performed without any special treatment. be able to.

However, in the case of this method, it is necessary to incorporate a relatively expensive actuator for the stop mechanism even in a lens barrel which does not have a problem with the aforementioned low-cost mechanical interlocking stop mechanism. In other words, a lens barrel that does not need to incorporate a relatively expensive actuator diaphragm mechanism must also incorporate the actuator, resulting in higher costs than a mechanically linked mechanism.

Further, in order to make the above two methods compatible, an aperture setting lever interlocked with an aperture mechanism interlocking lever on the lens barrel side, and information such as exposure and aperture value are electrically connected to the lens barrel. It is not preferable to have two control mechanisms, that is, a circuit mechanism for transmitting the signal to the camera side, because it complicates the camera body and increases the cost.

For this reason, for example, Japanese Patent Application Laid-Open No.
As proposed in Japanese Patent Application Publication No. 7-107, there is a system that converts the amount of movement of an aperture setting lever in a lens barrel into an equivalent electric signal and controls driving of an aperture mechanism by a motor based on the signal. It is known.

[0012]

However, in this case, the exposure result measured by the camera body is such that when the built-in photographing optical system is shifted and tilted with respect to the camera body and the image plane during the above-described tilt photographing, the image is obtained. Since the optical axis of the photographing optical system shifts and tilts with respect to the surface, the camera body designed so that proper exposure can be measured when the optical axis of the photographing optical system is substantially perpendicular to the image plane has a large error. This makes it impossible to obtain a desired aperture opening amount, making it impossible to perform shooting with proper exposure.

Further, in the case where the aperture amount changes with respect to the same aperture value during zooming in the zoom lens barrel, one aperture position in the aperture setting lever of the camera main body is moved relative to one aperture position in the aperture mechanism of the lens barrel. Since the amount is determined in a one-to-one relationship, it cannot cope with a change in the aperture opening amount due to zooming. For this reason, it is impossible to take a photograph with proper exposure.

An object of the present invention is to provide a lens barrel for electrically controlling the aperture opening based on the aperture information from the camera body side, in which the aperture opening changes during a shift and tilt operation or a zoom operation. Another object of the present invention is to provide a lens barrel capable of performing proper exposure.

[0015]

In order to achieve the above object, a lens barrel according to the present invention is provided with a photographing optical system, a diaphragm mechanism, a driving device for driving the diaphragm mechanism, and a camera body. A device that obtains an electric signal based on aperture information, a control device that controls the driving device based on the electric signal, and a detection device that detects a displacement amount caused by operation of the imaging optical system, The control device corrects a drive amount of the diaphragm mechanism by the drive device based on a detection result by the detection device.

According to the present invention, the driving amount of the diaphragm mechanism of the lens barrel is controlled by an electric signal based on the diaphragm information from the camera body side, and the photographing optical system is operated to generate a displacement and an appropriate exposure amount. Is changed, the amount of displacement is detected, and the amount of drive of the aperture mechanism is corrected based on the detection result. Therefore, it is possible to obtain an appropriate amount of exposure in consideration of the amount of displacement of the imaging optical system. Therefore, even if the photographing optical system is operated, photographing can always be performed with proper exposure. Further, since this correction is performed on the lens barrel side, no special mechanism or circuit is required on the camera body side, and a conventional camera body can be used.

Further, when the lens barrel has a shift / tilt mechanism, the displacement amount is at least one of a shift amount when the photographing optical system is shifted and a tilt amount when the imaging optical system is tilted. Thus, in the case of tilting photographing or the like, even if the photographing optical system is shifted and tilted, photographing can be performed with an appropriate exposure amount.

In the case where the lens barrel has a zoom mechanism, the displacement amount is a change amount of a focal length due to a zoom operation of the photographing optical system. Thus, an appropriate exposure amount can be obtained even during zoom shooting.

Further, the correction of the driving amount of the diaphragm mechanism is configured to change the diaphragm opening amount of the diaphragm mechanism based on the diaphragm information transmitted from the camera body based on the displacement amount. Thus, an appropriate aperture amount can be set in the aperture mechanism to obtain an appropriate exposure amount.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic longitudinal section when the lens barrel according to the present embodiment is mounted on a camera body. FIG. 2 is a diagram illustrating a configuration of a diaphragm mechanism provided in the lens barrel according to the present embodiment. As shown in FIG. 1, a lens barrel 2 is mounted on a camera body 1 constituting a camera body. The lens barrel 2 is
Between the second lens group 302 and the third lens group 303, and a three-group single-focus lens imaging optical system including the first lens group 301, the second lens group 302, and the third lens group 303. And a diaphragm 100 arranged.

The diaphragm 100 has diaphragm blades 17 and adjusts the amount of light reaching the image surface 1a, which is the film surface of the camera body, by adjusting the amount of aperture around the optical axis I. First lens group 301, second lens group 30
The second and third lens groups 303 and the stop 100 are positioned on the optical axis I.
By moving them in the same direction as arrow A without changing their relative positions, an image of the subject is formed on the image surface 1a.

The lens barrel 2 has a lens barrel configuration including a front lens barrel 2a, an intermediate lens barrel 2b, and a rear lens barrel 2c.
The rear lens barrel 2c is configured to be detachable from the camera body 1, and is rotatably supported with the optical axis I as a rotation center axis.

The intermediate barrel portion 2b has a substantially wedge-shaped engaging portion 21 at an end on the side of the rear barrel portion 2c, and engages with the engaging portion 22 of the rear barrel portion 2c. 2c is supported so as to be movable in the direction perpendicular to the plane of FIG. With this moving mechanism, the lens barrel 2 can be shifted.

The front lens barrel 2a has a cylindrical surface (convex shape) whose end surface 24 on the side of the intermediate lens barrel 2b is centered on an axis orthogonal to the optical axis I passing through a point C on the optical axis I. It is engaged with the concave end surface 23 of the intermediate lens barrel 2b. Thus, the front lens barrel 2a rotates with respect to the intermediate lens barrel 2b about the cylindrical axis together with the first lens group 301, the second lens group 302, the third lens group 303, and the diaphragm 100. Supported as possible. With this moving mechanism, the lens barrel 2 can be tilted.

The front lens barrel 2a comprises a first lens group 301,
The second lens group 302, the third lens group 303, and the stop 100 are movably supported in the direction of arrow A in the same direction as the optical axis I without changing their relative positions.

As described above, the first lens group 301 and the second lens group
Lens group 302, third lens group 303 and aperture 10
Numeral 0 is supported so as to be rotatable with respect to the camera body 1 and the image plane 1a and to be movable in a direction parallel and perpendicular to the optical axis I.

As described above, according to the lens barrel 2 of FIG. 1, the first lens group 30 which is a lens group of the photographing optical system is used.
By shifting and tilting the first, second lens group 302, the third lens group 303, and the aperture 100 with respect to the image plane 1a, the inclination of the object in the image plane 1a in the vertical and horizontal directions and the depth of the object are changed. be able to.

Next, the structure and operation of the diaphragm mechanism for driving the diaphragm 100 of the lens barrel shown in FIG. 1 will be described with reference to FIG. The diaphragm mechanism shown in FIG. 2 processes the electromagnetic diaphragm unit 16 and the diaphragm blade 17 constituting the diaphragm 100, the interlocking disk member 10 having the interlocking lever 10a and the rotation angle sensors 12 and 13, and processes the rotation angle information of the rotation angle sensor. A rotation angle processing circuit 14, an electromagnetic diaphragm drive control circuit 15 for controlling and driving an electromagnetic diaphragm unit 16 based on a signal from the rotation angle processing circuit 14, a shift amount for detecting a shift amount of a photographing optical system in a lens barrel. It includes a detection device 18 and a tilt amount detection device 19 for detecting the tilt amount.

The interlocking disk member 10 is supported rotatably about the center of the interlocking disk member 10 with respect to the lens barrel. One end of the coil spring 11 is fixed to the interlocking disc member 10, and the other end is fixed to the lens barrel. When the interlocking disc member 10 receives the elastic force of the coil spring 11 in the direction of the arrow F 'shown in the drawing, the interlocking disc member 10 is urged in the direction of the arrow W1 shown in the drawing and becomes rotatable. I have.

The interlocking disk member 10 is provided with a rotation angle sensor for detecting the rotation angle of the interlocking disk member 10 on the outer periphery. This rotation angle sensor is connected to the interlocking disc member 1.
And a slit plate 12 that rotates together with the
A rotation angle detection unit 13 including a D13a and an SPD 13b as a light receiving unit is provided. The slit plate 12 has an arc shape, and the center of the arc is the interlocking disc member 1.
It is fixed to the outer periphery of the interlocking disc member 10 so as to substantially coincide with the center of 0. A large number of slits 12 a are provided in the slit plate 12 radially on an extension of the center of the interlocking disk member 10.

The LED 13a and the SPD 13b in the rotation angle detector 13 are arranged so as to sandwich the slit plate 12. When the slit plate 12 is at a position where light from the LED 13a passes through the slit 12a, the light
It reaches PD13b. For this reason, the interlocking disc member 1
When 0 rotates, the SPD 13b is proportional to the rotation angle.
A pulse wave appears on the upper side, and the rotation angle of the interlocking disc member 10 can be detected by counting the number of the pulse waves.

The aperture setting lever A 'is provided on the camera body, and is configured to move based on an exposure result measured on the camera body side or an aperture value set by a user. The interlocking lever 10 a of the interlocking disc member 10 presses the aperture setting lever A ′ by the elastic force of the coil spring 11. In this mechanism, for example, when the aperture setting lever A ′ moves in the direction of the arrow W1 shown in FIG.
The interlocking disc member 10 rotates in the direction of the arrow W2 without a being separated from the aperture setting lever A '. That is, the movement amount y 'of the aperture setting lever A' and the rotation angle of the interlocking disc member 10 are directly proportional. Therefore, the amount of movement of the aperture setting lever A ′ and the number of pulse waves output from the SPD 13b in the rotation angle detection unit 13 are in direct proportion.

The pulse wave signal output from the rotation angle detection unit 13 is transmitted to a rotation angle processing circuit 14, and the rotation angle processing circuit 14 uses the number of pulse waves output from the rotation angle detection unit 13 to operate the interlocking disk member. The rotation angle of 10 is calculated.
The storage device of the rotation angle processing circuit 14 is
Correspondence data between the rotation angle of 0 and the drive amount of the diaphragm blade 17 is stored, and the drive amount of the diaphragm blade 17 corresponding to the rotation angle of the interlocking disk member 10 is calculated based on the correspondence data.

The value of the drive amount of the diaphragm blade 17 calculated by the rotation angle processing circuit 14 is transmitted to the electromagnetic diaphragm drive control circuit 15. The electromagnetic diaphragm drive control circuit 15 has a control circuit for controlling the driving amount of the diaphragm blade 17 by driving the motor in the unit of the electromagnetic diaphragm unit 16, and the driving amount of the diaphragm blade 17 transmitted from the rotation angle processing circuit 14. Is transmitted to the electromagnetic diaphragm unit 16 on the basis of the value of.

As the electromagnetic diaphragm unit 16, a known one can be used and is fixed to the lens barrel. The electromagnetic diaphragm unit 16 drives the diaphragm blades 17 by the calculated driving amount by a motor in the unit according to a command from the electromagnetic diaphragm drive control circuit 17, and changes the aperture opening amount D formed by the diaphragm blades 17.

As described above, according to the aperture mechanism shown in FIG. 2, the amount of drive of the aperture blade 17 can be controlled by the amount of movement y 'of the aperture setting lever A'. It can be controlled by the movement amount y 'of the setting lever A'. Thus, an exposure amount corresponding to the aperture information from the camera body can be obtained by the aperture 100.

The rotation angle of the interlocking disk member 10 stored in the storage device in the rotation angle processing circuit 14 and the aperture blade 1
By making the data corresponding to the driving amount of 7 non-linear,
Aperture blade 17 for moving amount y 'of aperture setting lever A'
Can be made non-linear.

Next, a description will be given of the correction of the aperture amount when the photographing optical system shown in FIG. 1 is shifted and tilted. As the photographing optical system shifts and tilts, the optical axis I is also shifted and tilted with respect to the image plane 1a. When the optical axis I does not shift or tilt, that is, when the photographing optical system is in a normal state, a photometric element (not shown) provided in the camera body 1 performs accurate photometry based on this state. Due to the arrangement, an error occurs in the photometric value at the time of shift and tilt movement of the imaging optical system.

By shifting and tilting the lens barrel, a shift amount and a tilt amount generated when the photographing optical system shifts and tilts are detected by a shift amount detecting device 18 and a tilt amount detecting device 19 shown in FIG. Then, it is transmitted to the rotation angle processing circuit 14. The displacement amount sensor unit in the shift amount detecting device 18 and the tilt amount detecting device 19 is provided in a lens barrel, and can be configured by a rotation angle detecting device such as a brush encoder.
The configuration is not limited to this, and another configuration may be used as long as the amount of displacement can be detected and converted into an electric signal.

The storage device of the rotation angle processing circuit 14 stores, in addition to the data corresponding to the rotation angle of the interlocking disk member 10 and the driving amount of the diaphragm blade 17, the driving amount of the diaphragm blade 17 with respect to the shift amount and the tilt amount. Corresponding data of the correction amount is stored, and based on this correspondence data, the correction drive amount of the diaphragm blade 17 corresponding to the rotation angle of the interlocking disk member 10 and corresponding to the shift amount and the tilt amount is calculated.

The value of the correction drive amount of the diaphragm blade 17 calculated by the rotation angle processing circuit 14 in this way is transmitted to the electromagnetic diaphragm drive control circuit 15. The electromagnetic diaphragm drive control circuit 15 controls the diaphragm blades 17 transmitted from the rotation angle processing circuit 14.
The drive command of the required correction drive amount of the aperture blade 17 is transmitted to the electromagnetic aperture unit 16 according to the value of the correction drive amount. The electromagnetic diaphragm unit 16 includes the electromagnetic diaphragm drive control circuit 1
In accordance with the command from 7, the aperture blade 17 is driven by the correction drive amount by the motor in the unit, and the aperture opening amount D formed by the aperture blade 17 is changed.

As described above, the driving amount of the diaphragm blade 17 can be controlled by the moving amount y 'of the diaphragm setting lever A', in other words, the diaphragm opening amount D can be controlled by the moving amount y 'of the diaphragm setting lever A'. Further, since the diaphragm blade 17 can be driven with a drive amount corrected for a photometric error in the camera body that occurs when the photographing optical system is shifted and tilted, the diaphragm opening amount D is corrected according to the shift amount and the tilt amount. can do. Therefore, even if the photographing optical system is shifted and tilted, photographing can always be performed with an appropriate exposure amount.

In the case of a zoom lens barrel having a built-in zoom encoder for detecting the set focal length, the rotation angle of the interlocking disk member 10 stored in the storage device in the rotation angle processing circuit 14 and the driving of the aperture blade 17 By changing the data corresponding to the amount in accordance with the focal length detected by the zoom encoder, it is possible to correct the aperture D in accordance with the amount of change in the focal length due to the zooming operation.

As described above, according to the lens barrel according to the present embodiment, the correction of the photometric error when the photographing optical system is shifted and tilted can be performed while the system on the camera body side remains unchanged. This can be achieved by correcting the aperture D in the system in the lens barrel. That is, the system in the lens barrel can correct the aperture amount D by non-mechanical interlock based on the movement amount y 'of the aperture setting lever A' on the camera body side. As a result, even in a lens barrel in which it is difficult to control the aperture opening amount D based on the movement amount y 'of the aperture setting lever A' on the camera body due to mechanical interlocking, a conventional mechanism is used on the camera body side. As it is, it becomes possible to control the aperture amount D based on the aperture information from the camera body.

Further, by providing a photometric error correcting means for shifting and tilting which is not used in a normal lens in the lens barrel, correction of the aperture opening for coping with photometric errors can be performed by the camera body and the lens mirror. It is possible to perform the communication without performing complicated communication with the tube and without falling into a correction impossible state due to a defective contact point between the camera body and the lens barrel. Furthermore, since the conventional mechanism can be used as it is on the camera body side, it is possible to correct a photometric error that occurs when the photographing optical system is shifted and tilted without increasing the cost of the camera body.

Note that this conventional method is applied to a lens barrel employing a method of controlling the aperture opening amount D with the movement amount y 'of the aperture setting lever A' on the camera body side by conventional mechanical interlocking. Since the aperture D can be controlled, the lens barrel employing the conventional mechanical interlocking method does not require specially built-in actuators, sensors, processing circuits, etc. for controlling the aperture D, and is inexpensive. It becomes possible to manufacture a lens barrel.

[0047]

According to the present invention, in a lens barrel for electrically controlling the aperture opening based on the aperture information from the camera body side, the change in the aperture opening during shift and tilt operations and zoom operation. , It is possible to obtain an appropriate exposure amount at the time of shooting.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view when a lens barrel according to an embodiment of the present invention is mounted on a camera body.

FIG. 2 is a diagram showing a configuration of a diaphragm mechanism provided in the lens barrel shown in FIG.

FIG. 3 is a diagram showing a configuration of an aperture mechanism provided in a conventional lens barrel.

[Description of Signs] 1 Camera body 1a Image plane 2 Lens barrel 10 Interlocking disk member 10a Interlocking lever 11 Coil spring 12 Slit plate 12a Slit 13 Rotation angle detection unit 13a LED (light emission unit) 13b SPD (light reception unit) 14 Rotation angle Processing Circuit 15 Electromagnetic Aperture Drive Control Circuit 16 Electromagnetic Aperture Unit 17 Aperture Blade 18 Shift Amount Detector 19 Tilt Amount Detector 100 Aperture A 'Aperture Setting Lever I Optical Axis

Claims (4)

[Claims] A photographing optical system; a diaphragm mechanism; a driving device for driving the diaphragm mechanism; a device for obtaining an electric signal based on diaphragm information transmitted from a camera body; A control device for controlling the drive device; and a detection device for detecting a displacement amount caused by operation of the photographing optical system; and the diaphragm mechanism by the drive device based on a detection result by the detection device in the control device. A lens barrel for correcting a driving amount of the lens barrel. 2. The lens barrel according to claim 1, wherein the displacement amount is at least one of a shift amount when the imaging optical system is shifted and a tilt amount when the imaging optical system is tilted. 3. The lens barrel according to claim 1, wherein the displacement amount is a change amount of a focal length due to a zoom operation of the photographing optical system. 4. The method according to claim 1, wherein the correction of the driving amount of the diaphragm mechanism changes the diaphragm opening amount of the diaphragm mechanism based on the diaphragm information transmitted from the camera body based on the displacement amount. The lens barrel according to claim 1, 2, or 3.