JPH028265Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a distance control device used in a camera.

In general, the active method that projects infrared light toward the subject from the camera side and performs triangulation by receiving the reflected light from the subject is often used as the distance measurement method for autofocus (automatic focus adjustment) in compact cameras. . However, conventional methods use the distance signal obtained by the above active method to display the distance, drive the lens, etc., and detect the movement of the meter pointer using a step-like cam mechanism. Various methods can be considered, such as a method of starting an electromagnetic drive device and stopping it in a predetermined position with a locking member, and a method using a servo motor, but these methods have drawbacks such as large size, high current consumption, and complicated structure. .

Therefore, the present invention eliminates the above-mentioned drawbacks and provides a distance control device suitable for low- and intermediate-class cameras that is capable of three-step focus adjustment of near, middle, and far distances.

According to the present invention, there is provided a rotor consisting of a rotatably supported permanent magnet magnetized with two radial poles, a stator having a pair of magnetic poles facing the outer periphery of the rotor, and a distance from a coil that excites the stator. An electric circuit is provided that can control energization and de-energization of the coil in the forward and reverse directions based on the detected information, and also directly or indirectly controls the lens drive or displays the distance in conjunction with the rotor. This is achieved by providing a drive lever and a second magnetic pole that stops the rotor so that the rotor pole is orthogonal to the magnetic field direction of the stator magnetic pole when the coil is not energized.

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

A rotor 1 consisting of permanent magnets magnetized with two poles of N and S in the radial direction is integrally fixed to a rotor shaft 2. One end of the rotor shaft 2 is rotatably supported by a hole in the lower plate 3, and the other end is rotatably supported by a hole in the upper plate 4. A drive lever 5 is fixed. A stator 6 has two magnetic pole portions 6a facing the outer periphery of the rotor 1, and the magnetic pole portions 6a are integrally connected via a narrow portion 6b. Further, the gap between the stator 6 and the rotor 1 is such that the gap δ ₁ of the narrow portion 6b is smaller than the gap δ ₂ of the magnetic pole portion 6a, and the inner shape of the stator 6 is an oval hole.
The center line of a (Y axis) and the center line of the two narrow parts (X
The narrow portion 6b is formed to serve as a second magnetic pole by arranging the two axes so that they are perpendicular to each other. On the other hand, a coil 7 that generates a magnetic field in the magnetic pole portion 6a of the stator is connected to an electric circuit to be described later and is wound around a coil frame 8 in which an iron core 9 is inserted in the center. And the stator 6
is positioned on the lower plate 3 by a guide means (not shown), and the iron core 9 is superimposed so as to be magnetically connected to the stator 6, and the upper plate 4
and the lower plate 3 are fixed by screwing with set screws 10. The drive lever 5 fixed to the rotor shaft 2 is connected to a pin 4a provided on the upper plate 4 and has a rotation range 5a, 5b that regulates the range of rotation in the forward and reverse directions. It has a connecting pin 5c that transmits rotational movement to a control lever 11, which will be described later. Reference numeral 11 denotes a control lever that is located near a groove 11a that fits with the connecting pin 5c and a locking portion 11b that engages with a distance ring 12 (described later).
It has an indicator part 11c for displaying middle and far distance information on a viewfinder, etc., and is rotatably supported. Reference numeral 12 denotes a distance ring, which has a three-stage stepped cam portion 12a that engages with a locking portion 11b of the control lever, and a locking portion 12b that engages with a locking hole 13, which will be described later, and is rotatable. It is supported and urged counterclockwise by a spring 15. The distance ring 12 is linked to a lens system (not shown), and is configured such that focus can be adjusted by rotating the distance ring 12. 1
Reference numeral 3 denotes a locking claw, which has a claw portion 13a that engages with the locking portion 12b of the distance ring, and an arm portion 13b that engages with a release plate 14, which will be described later, and is rotatably supported and rotated clockwise by a spring 16. is energized by 1
Reference numeral 4 denotes a release plate, which has an engaging part 14a that engages with the arm part 13b of the locking claw, and a pin 14b that operates a switch SW, which will be described later. In the figure, it is urged upward.

FIG. 4 shows a distance measuring configuration diagram used in the distance control device of the present invention, which is a known active type distance measuring system. Reference numeral 20 denotes a light emitting element such as a red LED, and a light emitting circuit 21 projects light onto a subject 23 through a light projecting lens 22. The reflected light reflected by the subject 23 passes through the light receiving lens 24 to the PSD.
The incident image is formed on a semiconductor position detection element 25 such as (Position Sensitive Detectors). This imaging position is 25a,
25b for medium distance position 23b, short distance position 2
3c and 25c, and the imaging position of the reflected spot light differs depending on the distance. Since the output current of the detection element 25 differs depending on the difference in the imaging position, this output current is used as distance information. The above output current is input to a control circuit 27 via a detection circuit 26, and this control circuit 27 directs the current to the coil 7 in the A direction (forward direction) when the distance is long, and in the B direction (reverse direction) when the distance is short. ) is energized, and the circuit is configured to be in a non-energized state during intermediate distances. Furthermore, the control circuit 27 includes a switch that is opened and closed by the camera release operation.
The switch SW is connected to the light projection circuit 21, and distance measuring operation is performed by turning on the switch SW.

The operation of the above configuration will be explained below.

When the coil 7 is not energized, due to the difference between the gap δ ₁ and δ ₂ between the stator 6 and the rotor 1, the attractive force between the NS pole of the rotor 1 and the narrow part 6b of the stator becomes the attractive force with the magnetic pole part 6a of the stator. Since the NS pole of the rotor 1 stops along the center line (X-axis) of the narrow part 6b of the stator, this state is maintained continuously unless energized. Next, in FIG. 1, for example, the N pole of the rotor 1 is on the minus X axis and the S pole is on the plus X axis, and when the coil 7 is energized in the positive direction, a magnetic field is generated, and this magnetic field is transmitted through the iron core 9 to the stator. 6, the magnetic pole part 6a on the positive Y axis has an N pole, and the magnetic pole part 6a on the negative Y axis
When an S pole occurs in the rotor 1, the attraction force between the NS pole of the rotor 1 and the narrow part 6b of the stator is
Since the attractive force between the NS pole and the magnetic pole part 6a of the stator is strong, the rotor 1 begins to rotate counterclockwise until the driving lever's determining part 5a contacts the pin 4a of the upper plate, causing the coil 7 to move in the positive direction. The rotor 1 is stopped in this state while energized. Then, when the current to the coil is cut off, the NS of rotor 1 is turned off again.
The poles and the narrow part 6b of the stator are attracted to each other and the rotor 1 is
The NS pole and the narrow part 6b of the stator return to the opposing state. Further, in FIG. 1, when a current is applied in the opposite direction to the coil 7, an S pole is generated in the positive Y-axis direction of the magnetic pole portion 6a of the stator, and an N pole is generated in the negative Y-axis direction, and the rotor 1 is clockwise rotated. It rotates in the direction until the determining part 5b of the drive lever contacts the pin 4a of the upper plate and then stops. When the current to the coil 7 is cut off, the coil 7 returns to its non-energized state. Note that the rotation angle of the rotor 1 and the drive lever 5 is appropriately set to an angle of 1/6 rotation or less in each direction, taking into account the above-mentioned return operation when energization is interrupted, responsiveness when energization, rotational output torque, etc. It is something that

On the other hand, FIG. 3 shows the state before the camera is released, in which the locking part 12b of the distance ring and the locking part 13a of the locking claw are locked, and the distance ring 12 is rotated counterclockwise. is regulated. Further, the release plate 14 is urged upward by the spring 17 to turn the switch SW into the OFF state, and the engaging portion 14 of the release plate
a and the arm portion 13b of the locking claw are not engaged with each other. Furthermore, since the switch SW is in the OFF state, the electrical circuit is also
In the OFF state, the coil 7 is not energized. Therefore, the drive lever 5 is stopped at the neutral position, and the locking part 11b of the control lever that is interlocked with the drive lever 5 is stopped at a position corresponding to the central stepped part of the cam part 12a of the distance ring. .

If you operate the camera release in this state,
In FIG. 3, the release plate 14 is moved downward against the spring force of the spring 17. As the release plate 14 descends, the switch SW is first turned on.
When this state is reached, the light emitting element 20 is turned on by the control circuit 27 and the light projection circuit 21, and light is projected onto the subject 23 via the light projection lens 22. The projected light is the subject 23
The reflected light is incident and imaged on the semiconductor position detection element 25 via the light receiving lens 24, and the output current of the detection element 25 according to the distance to the subject 23 is transmitted via the detection circuit 26 to the control circuit 27. Further, the control circuit 27 controls the energization of the coil 7 according to the far, middle, and near distances.

Therefore, when the distance to the subject is long, current flows in the coil 7 in the A direction (positive direction) and the rotor 1
rotates counterclockwise, and when the distance is intermediate, no current flows through coil 7, so rotor 1 stops at the neutral position; when the distance is short, current flows through coil 7 in direction B (reverse direction). Since the rotor 1 rotates clockwise, the drive lever 5, which is interlocked with the rotor 1, can have three rotational positions: a counterclockwise rotational position, a neutral position, and a clockwise rotational position, depending on the distance. Since the stopping position of the locking part 11b and index part 11c of the control lever linked to the drive lever 5 is determined, distance measurement information can be easily obtained by looking at the index part 11c in the viewfinder at the initial stage of the release operation. It will be done.

Further, as the release plate 14 moves downward, the engagement part 14a of the release plate engages with the arm part 13b of the locking pawl, and the engagement pawl 13 is rotated counterclockwise and engaged with the locking part 12b of the distance ring. Locking part 13a of the pawl
is released and the distance ring 12 begins to rotate counterclockwise. However, since the stopping position of the locking portion 11b of the control lever is determined according to the distance as described above, the predetermined step portion of the cam portion 12a and the locking portion 11
b engages and stops. Therefore, three stopping positions of the control lever 11 are selected according to near, medium, and long distances, so the rotation angle of the distance ring 12 is determined by the stopping position of the control lever 11 and the three step-shaped cam portions 12a. Three ways are selected, and this circuit angle is further transmitted to the lens system linked to the distance ring 12 to perform focus adjustment. Thereafter, a well-known camera exposure device (not shown) is activated to take a picture, and the release plate 14 is returned to its initial position by the force of the spring 17, and the distance ring 12 is moved in preparation for the next picture. The locking pawl 13 and the like are in the state shown in FIG. 3.

Note that if the release operation is interrupted within the operating range where the engaging part 14a of the release plate and the arm part 13b of the locking claw are not related, the release plate 14 will be returned to its initial state by the spring 17, so no photographing will be performed and distance measurement will be performed. operation is possible. Furthermore, by adding a latch circuit that maintains the energized state of the coil 7 controlled by distance information while the switch SW in the control circuit 27 is ON, a release operation within the operating range of the release plate 14 can be performed. It is also possible to measure the distance to the object, change the photographing range in which the distance was measured, and then press the release plate 14 downward to take the photograph.

In the above description, the control lever is provided with a locking part that engages with the step cam part of the distance ring and an index part that displays distance information, but the locking part and index part may also be provided on the drive lever. A similar effect can be obtained.

As explained above, in the present invention, a distance control device for a camera is constructed using an electromagnetic drive device that is an improved stator type step motor.Moreover, as a means of obtaining an intermediate position in three-position control, the distance control device for a camera is constructed using an electromagnetic drive device that is an improved version of a stator-type step motor. Since this is carried out, no external force such as a spring is required, resulting in high efficiency, low current consumption, and miniaturization.In addition, the structure is simple and the number of components is small, so it is economically advantageous. Furthermore, even if the rotor and drive lever become inoperable due to exhaustion of the camera's built-in battery, etc., the focal length can be adjusted to an intermediate distance, thereby avoiding the worst situation of photographing in an extremely out-of-focus state.

[Brief explanation of the drawing]

Fig. 1 is a partial plan view of the present invention, Fig. 2 is a sectional view of Fig. 1, Fig. 3 is a plan view of the entire invention, Fig. 4
The figure is a diagram of the distance measurement configuration used in the present invention. 1... Rotor, 5... Drive lever, 6... Stator, 7... Coil, 11... Control lever, 1
2...Distance ring.

Claims (1)

[Scope of utility model registration request] A rotor consisting of a rotatably supported permanent magnet magnetized with two radial poles; a stator having a pair of magnetic poles facing the outer periphery of the rotor; a coil for exciting the stator; and a coil for exciting the stator. an electric circuit that can control energization and de-energization in the forward and reverse directions, and a drive lever that works in conjunction with the rotor to directly or indirectly control lens drive or display distance; A distance control device for a camera, characterized in that a second magnetic pole is provided for stopping the rotor so that the pole of the rotor is perpendicular to the magnetic field direction of the magnetic pole of the stator when the coil is not energized.