JP4844995B2 - Lens drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens driving device that is used in a portable small camera and zooms an object.
[0002]
[Prior art]
As this type of lens driving device, a device using a combination of a stepping motor and a feed screw transmission mechanism is known, and this lens driving device is shown in FIG. As shown in FIG. 5, the lens driving device 100 transmits the shaft of the rotating stepping motor 101 to the feed screw 103 via the gear 102 to convert the rotational motion into a straight motion. A lens 105 is fixed on a nut 104 guided and driven on the feed screw 103. Therefore, the linear position of the lens 105 is determined according to the rotation angle of the stepping motor 101.
[0003]
[Problems to be solved by the invention]
However, the above-described technique requires a complicated transmission mechanism such as the stepping motor 101, the gear 102, the feed screw 103, and the nut 104, so that there is a problem that the apparatus becomes large and expensive.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a lens driving device that is small and light and inexpensive.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 includes a front support frame that supports the front lens, a front coil attached to the rear of the front support frame, a front spring attached to the rear of the outer periphery of the front support frame, and a rear lens. A rear support frame for supporting, a rear coil attached to the rear of the rear support frame, a rear spring attached to the rear of the inner periphery of the rear support frame, a magnet, and a yoke. The yoke has an outer wall and an outer wall. The magnet is disposed between the outer wall and the inner wall of the yoke, and forms an outer gap between the outer wall of the yoke and an inner gap with the inner wall of the yoke. And having different magnetic poles on the side facing the outer wall and the side facing the inner wall, the front coil is disposed in the outer gap, the rear coil is disposed in the inner gap, and applying a current to the front coil, Forward Moving the lens to the front, by applying an electric current to the rear coil, and wherein the moving the rear lens forward.
The invention according to claim 2 supports the front support frame that supports the front lens, the front coil attached to the front support frame, the front spring that biases the front support frame toward the rear, and the rear lens. A rear support frame, a rear coil attached to the rear support frame, a rear spring for biasing the rear support frame toward the rear, a magnet, and a yoke are provided. The yoke is disposed on the outer wall and the inner peripheral side of the outer wall. The magnet is disposed between the outer wall and the inner wall of the yoke to form an outer gap with the outer wall of the yoke and an inner gap with the inner wall of the yoke. The opposite side and the side facing the inner wall have different magnetic poles, the front coil is placed in the outer gap, the rear coil is placed in the inner gap, and the current is applied to the front coil so that the front lens is moved forward. Move By applying a current in a square coil, and wherein the moving the rear lens forward.
[0006]
In the first and second aspects of the invention, since the front coil is disposed in the outer gap between the magnet and the yoke and the rear coil is disposed in the inner gap between the magnet and the yoke, when a current is applied to the front coil, The front lens can be moved forward by the action of the electromagnetic force of the outer gap, and when a current is applied to the rear coil, the rear lens can be moved forward by the action of the electromagnetic force of the inner gap. Thereby, the structure of the apparatus can be made simple and small.
[0007]
In the first and second aspects of the invention, the amount of movement of the front lens is determined by the balance between the elastic force of the front spring and the electromagnetic force based on the amount of current applied to the front coil, and the amount of movement of the rear lens. Is preferably determined by balancing the elastic force of the rear spring and the electromagnetic force based on the amount of current applied to the rear coil .
[0008]
The amount of movement of the front lens is determined by a balance between the elastic force of the front spring and the electromagnetic force based on the amount of current applied to the front coil. The amount of movement of the rear lens is determined by the elastic force of the rear spring and the rear coil. Therefore, each of the front lens and the rear lens can be easily moved by a desired amount. As a result, the structure of the apparatus can be made smaller and less expensive.
[0009]
In the first and second aspects of the present invention, the front spring and the rear spring are halved, and one is an energization path from the plus side of the applied current to the winding start side of the front coil and the rear coil, and the other is the front It is preferable to use an energization path from the winding end side of the coil and the rear coil to the minus side .
[0010]
The front spring and the rear spring are halved, one is the current path from the plus side of the applied current to the winding start side of the front coil and the rear coil, and the other is the minus side from the winding end side of the front coil and the rear coil Since it is made into the electricity supply path to, the elastic lead wire for electricity supply can be abbreviate | omitted.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a sectional view showing a lens driving device according to the present invention, FIG. 2 is an exploded perspective view of the lens driving device of FIG. 1, and FIG. 3 is an enlarged perspective view of a spring shown in FIGS. FIG. 4 is a cross-sectional view showing the operation of the lens driving device of FIG.
[0012]
The lens driving device 1 includes a front lens 2, a front support frame 3, a front coil 4, a front spring 5, a rear lens 6, a rear support frame 7, a rear coil 8, a rear spring 9, and a magnet 10. The yoke 11 is provided, and the front lens 2 is moved forward by applying a direct current to the front coil 4, and the rear lens 6 is moved forward by applying a direct current to the coil 8. It has become. In the present specification, the terms “front” and “rear” are used as appropriate. This indicates the positional relationship between the front and the rear relative to the subject from the camera.
[0013]
The ring-shaped front support frame 3 is an electrical insulator such as a synthetic resin, supports the front lens 2 at the center, includes a front coil 4 at the rear on the outer peripheral convex portion, and has a front spring at the outermost peripheral portion. The inner peripheral part (a) of 5 is fixed.
[0014]
Similarly, the ring-shaped rear support frame 7 is an electrical insulator such as a synthetic resin, supports the rear lens 6 at the center, includes a rear coil 8 on the rear on the outer peripheral convex portion, and has the innermost peripheral portion. The inner peripheral part (A) of the rear spring 9 is fixed to the inner part.
[0015]
The ring-shaped yoke 11 has a shape including an outer wall 11a, an inner wall 11b, and a bottom surface 11c. The outer wall 11a has a wall height larger than that of the inner wall 11b, and a ring-shaped magnet 10 is fixed on the bottom surface 11c. . The magnet 10 is magnetized in the radial direction, and a magnetic path is formed by the outer wall 11a, the inner wall 11b, and the bottom surface 11c.
[0016]
The front coil 4 is disposed between the gap formed by the magnet 10 and the outer wall 11a. Similarly, the rear coil 8 is disposed between the gap formed by the magnet 10 and the inner wall 11b. The outer peripheral portion (b) of the front spring 5 is fixed to the upper end of the outer wall 11a via the outer peripheral insulating ring 12, and similarly the outer peripheral portion (b) of the rear spring 9 is connected to the inner wall via the inner peripheral insulating ring 13. It is fixed to the upper end of 11b.
[0017]
FIGS. 3A and 3B are perspective views showing the structures of the front spring 5 and the rear spring 9, wherein FIG. 3A shows a folded state and FIG. 3B shows an extruded state. Show. The front spring 5 and the rear spring 9 are divided in half, and the spring property is maintained in the folded shape (a) when no external force is applied, and is extruded when the external force is applied (b). Deforms to the shape of
[0018]
The inner peripheral part (A) of the front spring 5 is fixed to the outermost peripheral part of the front support frame 3, and the outer peripheral part (B) is fixed to the upper end of the outer wall 11a. The frame 3 is positioned substantially in contact with the upper end of the outer wall 11a. Similarly, the inner peripheral part (A) of the rear spring 9 is fixed to the innermost peripheral part of the rear support frame 7, and the outer peripheral part (B) is fixed to the upper end of the inner wall 11b, so that no external force is applied. At times, the rear support frame 7 is positioned substantially in contact with the upper end of the inner wall 11b.
[0019]
The start and end of winding of the front coil 4 are both arranged on the front support frame 3 side, the start of winding is connected to one of the halves of the inner periphery (A) of the front spring 5, and the end of winding is halved. Connect to the other of the two. Furthermore, at the upper end of the outer wall 11a, the plus side of the current terminal for the front coil 4 is connected to one half of the outer peripheral portion (b) of the front spring 5, and the minus side is connected to the other half.
[0020]
With this connection, the current applied to the front coil 4 starts from the plus side via the one outer peripheral part (b) and inner peripheral part (b) of the front spring 5 and starts to wind the front coil 4. The applied end of the winding flows out to the minus side via the other inner peripheral part (A) and outer peripheral part (B) of the other half.
[0021]
Similarly, the winding start and the winding end of the rear coil 8 are both arranged on the rear support frame 7 side, and the winding start is connected to one half of the inner peripheral portion (A) of the rear spring 9 to complete the winding. Is connected to the other half. Furthermore, at the upper end of the inner wall 11b, the plus side of the current terminal for the rear coil 8 is connected to one half of the outer peripheral portion (b) of the rear spring 9, and the minus side is connected to the other half.
[0022]
Due to this connection, the current applied to the rear coil 8 starts from the plus side via the one outer peripheral portion (b) and inner peripheral portion (b) of the rear spring 9 and starts to wind the rear coil 8. The applied end of the winding flows out to the minus side via the other inner peripheral part (A) and outer peripheral part (B) of the other half.
[0023]
The outer peripheral insulating ring 12 and the inner peripheral insulating ring 13 are interposed between the outer peripheral portion (b) of the front spring 5 and the upper end of the outer wall 11a and between the outer peripheral portion (b) of the rear spring 9 and the upper end of the inner wall 11b, respectively. Thus, the spring, which is a conductor, and the yoke 11 are insulated.
[0024]
Next, the operation of the present embodiment will be described based on the configuration described above. In order to assemble the lens driving device 1, first, the front lens 2 is assembled into the front support frame 3, the front spring 5 and the outer peripheral insulating ring 12 are fixed (adhered) in this order, and then the front support frame 3. The front coil 4 is fixed (adhered) to the convex portion of the wire, and the start and end of winding are respectively connected to one and the other of the inner peripheral portion (A).
[0025]
Subsequently, similarly, the rear lens 6 is incorporated in the rear support frame 7, the rear spring 9 and the inner peripheral insulating ring 13 are fixed (adhered) in this order, and then the rear coil 8 is mounted on the convex portion of the rear support frame 7. Are fixed (adhered), and the start and end of winding are respectively connected to one side and the other side of the inner peripheral portion (A).
[0026]
The magnet 10 is fixed (adhered) by positioning in advance on the bottom surface 11 c of the yoke 11. While inserting the rear coil 8 into the gap between the magnet 10 and the inner wall 11b, the inner peripheral insulating ring 13 is fixed (adhered) to the upper end of the inner wall 11b, and one of the outer peripheral portions (b) and the other are respectively connected to the rear coil 8. Connect the positive and negative terminals of the current terminal.
[0027]
Similarly, while inserting the front coil 4 into the gap between the magnet 10 and the outer wall 11a, the outer peripheral insulating ring 12 is fixed (adhered) to the upper end of the outer wall 11a, and one and the other of the outer peripheral portions (b) are respectively connected to the front. Connect the current terminal for coil 4 to the plus side and minus side.
[0028]
The positive and negative connections for the rear coil 8 are drawn out to the outside by lead wires along the outer peripheral side of the inner wall 11b, and the positive and negative connections for the front coil 4 are drawn to the outside by lead wires along the outer peripheral side of the outer wall 11a. The structure is such that a direct current is applied to each of the lead wires.
[0029]
FIG. 4 shows a cross-sectional view when a DC current is applied to the front coil 4 and the rear coil 8 to operate the lens driving device 1 in the zoom state.
[0030]
When a current is applied to the front coil 4, an electromagnetic force forward (upward in FIG. 4) acts on the front lens 2, but the elastic force of the front spring 5 is rearward (downward in FIG. 4) in proportion to the displacement. ) Work. Therefore, the position of the front lens 2, that is, the moving distance forward is a point where the electromagnetic force and the elastic force are balanced.
[0031]
Thereby, the amount of movement of the front lens 2 can be determined by the amount of current applied to the front coil 4. Similarly, the amount of movement of the rear lens 6 can be determined by the amount of current applied to the rear coil 8.
[0032]
That is, the amount of movement of each of the front lens 2 and the rear lens 6 can be determined by the respective current amounts applied to the front coil 4 and the rear coil 8, so that the rear lens 6 is further rearward (lower in FIG. 4). Along with the action of the fixed lens 14 located inside the camera, the subject image can be zoomed and focused on the image plane 15 such as a CCD.
[0033]
Note that the convex shape of the front support frame 3 to which the front coil 4 is fixed and the convex shape of the rear support frame 7 to which the rear coil 8 is fixed are the front support frame 3 and the rear support frame 7 depending on the respective applied currents. This is a shape for creating a short coil structure in which the amount of magnetic flux linkage does not change even if moves forward.
[0034]
In this way, the amount of movement of each of the front lens 2 and the rear lens 6 can be controlled only by controlling the two current amounts supplied to the lens driving device 1, thereby zooming the object image. Further, if the applied current is set to zero, the zoom is not performed. Therefore, a direct current is required only during zooming, and power consumption can be saved.
[0035]
The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the invention. For example, in FIGS. 1 and 4, if the outer peripheral portions of the front support frame 3 and the rear support frame 7 are widened and deformed so as to move along the cylindrical guide, the parallelism of the front lens 2 and the rear lens 6 is maintained. A moving operation can be realized.
[0036]
Further, for example, if the front coil 4 is not directly fixed to the front support frame 3 and is disposed via the feed mechanism, the amount of movement of the front lens 2 can be increased, and the amount of movement of the rear lens 6 is also the same. Can be expanded.
[0037]
Further, in FIG. 3, the front spring 5 and the rear spring 9 have a halved structure, and each is used as a plus-side and minus-side energization path. May be used.
[0038]
【The invention's effect】
In the first and second aspects of the invention, the front lens can be moved forward by applying a current to the front coil, and the rear lens can be moved forward by applying a current to the rear coil. Therefore, the structure of the apparatus can be made simple and small.
[0039]
[0040]
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a lens driving device according to the present invention.
FIG. 2 is an exploded perspective view of the lens driving device of FIG.
FIG. 3 is an enlarged perspective view of the spring shown in FIGS.
4 is a cross-sectional view showing the operation of the lens driving device of FIG. 1. FIG.
FIG. 5 is a perspective view showing a conventional lens driving device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Front lens 3 Front support frame 4 Front coil 5 Front spring 6 Rear lens 7 Back support frame 8 Back coil 9 Back spring 10 Magnet 11 Yoke

Claims (2)

A front support frame for supporting a front lens, a front coil attached to the rear of the front support frame, a front spring mounted on an outer peripheral portion behind the front support frame, and a rear support frame for supporting the posterior lens, the rear support A rear coil attached to the rear of the frame, a rear spring attached to the rear of the inner periphery of the rear support frame, a magnet, and a yoke, the yoke including an outer wall and an inner wall located on the inner peripheral side of the outer wall The magnet is disposed between the outer wall and the inner wall of the yoke, forms an outer gap with the outer wall of the yoke, and forms an inner gap with the inner wall of the yoke, and the side facing the outer wall; have different magnetic poles at the side facing the inner wall, the front coil is arranged outside the gap, the rear coil is arranged inside the gap, by applying an electric current to the front coil to move the front lens in front, By applying a current in a square coil, the lens driving apparatus characterized by moving the rear lens forward. A front support frame that supports the front lens, a front coil attached to the front support frame, a front spring that biases the front support frame toward the rear, a rear support frame that supports the rear lens, and a rear support frame An attached rear coil, a rear spring that biases the rear support frame toward the rear, a magnet, and a yoke, the yoke having an outer wall and an inner wall located on the inner peripheral side of the outer wall, and a magnet Is arranged between the outer wall and the inner wall of the yoke and forms an outer gap between the outer wall of the yoke and an inner gap with the inner wall of the yoke, and the side facing the outer wall and the side facing the inner wall The front coil is arranged in the outer gap, the rear coil is arranged in the inner gap, and the current is applied to the front coil to move the front lens forward, and the current is applied to the rear coil. You It allows the lens driving apparatus characterized by moving the rear lens forward.

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