JP2007033541A - Lens barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens barrel, wherein looseness occurring when a lens holding frame is stopped is reduced, the lens holding frame is surely fixed, and a lens is smoothly driven when the lens is moved, that means, large driving force is not required. <P>SOLUTION: The lens barrel is equipped with a lens, a lens holder for holding the lens and a driving means for moving the lens holder in an optical axis direction, and a driving device having a magnet and a magnetic substance in a housing. The magnet is attached to either the lens holder or the housing, and the magnet or the magnetic substance is attached to the other, so that the lens holder is fixed by magnetic force between the magnet and the magnetic substance when stopping the lens holder. Then, the magnetic force between the magnet and the magnetic substance is made weaker when moving the lens holder than when stopping it. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens barrel in a video camera, a still camera, and other imaging apparatuses, and more particularly to a mechanism that securely holds a lens frame of a lens in a lens barrel.

  In recent years, in video camera lenses and the like, a high-magnification and compact lens is required, and in order to ensure optical performance, there is a demand for higher accuracy in lens barrels and lens frames. .

  The lens frame that is guided by the guide member provided in parallel with the optical axis of the lens and can be advanced and retracted in parallel with the optical axis prevents the “swing” during the advancing / retreating operation due to the backlash of the guide member. A method for improving the positional accuracy between the optical axis of the lens group held by the lens frame and the optical axis of the lens barrel by reducing as much as possible the fitting play with the guide member in order to securely hold the lens frame when stopped Is common.

As such a conventional example, there is JP-A-08-75974, and FIG. 6 shows a schematic diagram thereof. (FIG. 6 (a) is a front view, and FIG. 6 (b) is a top view of FIG. 6 (a) viewed from the reference guide shaft 2.)
In FIG. 6, a magnet 5 is attached to a part of the side surface of the lens holding frame 1 that engages with the reference guide shaft 2 extending along the optical axis direction and engages with the rotation restricting guide shaft 3 parallel to the reference guide shaft 2. A belt-like magnetic member 4 is disposed opposite to the magnet 5 on the inner surface of the lens barrel 6 in the forward / backward movement range of the lens holding frame 1 while maintaining a certain distance L, and the magnetic member of the magnet 5 The lens holding frame 1 is brought into contact with the reference guide shaft 4 and the rotation restricting guide shaft 3 at the same time by the action of the suction force to 4 to remove the fitting play, thereby preventing the “swing” during the holding frame advancement / retraction operation and stopping the holding frame. Sometimes the holding frame is securely fixed.
Japanese Unexamined Patent Publication No. 08-75974

  However, the above prior art has the following drawbacks.

  In the case of the configuration shown in FIG. 6, not only when holding the lens holding frame 1, but also when moving, the attractive force of the magnet 5 and magnetic member 4 is working, so a large force that exceeds the attractive force when moving is required. Become. Therefore, the motor of the drive source becomes large, which is disadvantageous for downsizing, and cost reduction is difficult.

  In addition, since the lens holding frame is always urged by a magnetic force, it is necessary to place a magnetic material having a length as long as the moving distance of the lens holding frame in the lens barrel. This is also disadvantageous for miniaturization because the body occupies it.

  Accordingly, an object of the present invention is to reduce the backlash when the lens holding frame is stopped, to securely fix the lens holding frame, and to drive smoothly when the lens is moved, that is, a lens mirror that does not require a large driving force. The purpose is to provide a tube.

  The object of the present invention described above is achieved by the following present invention.

  The lens includes a lens, a lens holder for holding the lens, a driving means for moving the lens holder in the optical axis direction, and a driving device having a magnet and a magnetic body. A magnet or magnetic body is attached to the lens holder, which is fixed by the magnetic force between the magnet and the magnetic body when the lens holder is stopped, and the magnetic force between the magnet and the magnetic body is weaker than when the lens holder is moved. This is a featured lens barrel. A preferable form thereof is a lens barrel in which permanent magnets are attached to both the housing and the lens holder. The lens barrel is characterized in that an electromagnet is attached to the housing and a magnetic material is attached to the lens holder. Further, the lens barrel is characterized in that the permanent magnet is attached to both the housing and the lens holder, and the permanent magnet on the housing side has a drive unit and is rotated by the drive unit. Then, the permanent magnet on the housing side is rotated so that the permanent magnet attached to the housing and the permanent magnet attached to the lens holder are attracted. A lens barrel characterized in that a permanent magnet attached to a magnet and a lens holder is repelled.

  As described above, according to the present invention, a magnetic body such as a magnet is disposed at the zoom point and the lens holder in the housing, and the magnitude of the magnetic force is switched between when the lens holder is stopped and when the lens holder is moved. When the lens holder is stopped, the lens holder is securely held, and when the lens holder is moved, it can be driven smoothly without requiring a large driving force. As a result, the motor can be downsized, and thus the lens barrel can be downsized.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  1 and 2 are diagrams according to the first embodiment of the present invention.

  FIG. 1 is a front view of the lens barrel of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. 101 is a lens, 102 is a lens holder that holds the lens 101, 103 and 104 are bars arranged parallel to the optical axis of the lens 101, the bar 103 guides the lens holder 102 to be movable in the optical axis direction, The bar 104 prevents the lens holder 102 from rotating about the bar 103. 105 is a lead screw, and the groove portion 105a of the lead screw is drawn only at the tip in FIG. 2, but originally has a groove to the root. A motor 106 is a power source for rotationally driving the lead screw. The lead screw 105 meshes with the rack 107 and is urged by the elastic member 108. The components 101 to 108 are housed in the housing 109.

  Further, permanent magnets 110a and 110b are attached to the lens holder 102, and the side facing the optical axis of both magnets is the S pole. Permanent magnets 111a and 111b are arranged at the position where the lens stops such as the zoom stop point of the housing, such as the Wide position / Tele position, and the permanent magnets 111a and 111b are bonded and fixed to the movable portion 122 of the plunger 121. Yes. The permanent magnet 111a has an S pole on the side facing the optical axis, and the permanent magnet 111b has an N pole on the side facing the optical axis.

  Plunger 121 is of an electromagnetic type, operates in response to a control signal, and moves movable part 122 back and forth. A coil spring 123 is attached to the movable part 122. The coil spring 123 biases the movable part 122 in the protruding direction.

  Next, the operation in the housing according to the present embodiment will be described.

  As shown in FIG. 2 (a), the power of the plunger 121 is turned off at the time of shooting, and the movable part 122 is protruded. As a result, the permanent magnet 111a fixed to the movable part 122 and the permanent magnet 110a attached to the lens holder attract each other by magnetic force, and the permanent magnet 111b and the permanent magnet 110b repel each other with their N poles facing each other. The holder 102 is biased and fixed upward.

  Next, when a zoom operation is performed by the photographer, the plunger 122 is energized and the movable portion 122 moves in the retracting direction as shown in FIG. As a result, the permanent magnets 111a and 111b fixed to the movable portion 122 are separated from the optical axis, and are attached to the lens holder, and the distance between the permanent magnets 110a and 111b and the permanent magnets 110b is increased. The magnetic force is weakened, and the lens holder 102 can move smoothly.

  By arranging the magnet at the zoom stop point in this way, the lens holder can be securely fixed by the magnetic force when the lens is stopped. Further, by moving the magnet on the housing side using the plunger, the magnitude of the magnetic force can be switched, and the driving force when the lens is moved can be reduced, so that the drive source can be downsized and the overall size can be reduced.

(Modification of Example 1)
In Example 1, as shown in FIG. 2 (a), at the time of shooting, all the plungers 121 in the casing are turned off. However, as shown in FIG. 3, only the point where the lens holder 102 has reached is shown. These plungers may be energized OFF, the lens holder 102 may be fixed, and the other plungers may be energized ON.

  Alternatively, at the plunger 121 at the point where the lens holder 102 has reached, only the upper plunger to be sucked may be turned off and only the lower plunger that will repel may be turned on.

  FIG. 4 is a diagram according to the second embodiment of the present invention.

  In FIG. 4, except for a part, the configuration is the same as that of the first embodiment. Here, for convenience of explanation, the same reference numerals are given to the components shown above, and the components shown on the left are shown. Will be described as needed, and components different from those of the first embodiment will be described with new reference numerals.

  In this embodiment, an electromagnet 211 is used instead of the permanent magnet 111 of the first embodiment shown above, and a magnetic body 210 is used instead of the permanent magnet 110 of the first embodiment.

  As shown in FIG. 4 (a), at the time of photographing, the electromagnet 211 at the position where the lens holder 102 has reached is energized, and the lens holder is fixed by the attractive force acting between the electromagnet 211 and the magnetic body 210.

  When the lens holder 102 is moved, the energization of the electromagnet is turned off, and the magnetic force acting between the electromagnet 211 and the magnetic body 210 is weakened.

  By turning the electromagnet energization on or off in this way, the magnitude of the magnetic force acting on the electromagnet and the magnetic body can be easily switched. When the energization is on, the lens holder is securely fixed, and when the energization is off, the lens is The driving force when moving the holder can be reduced.

  FIG. 5 is a diagram according to the third embodiment of the present invention.

  5 (a-1) and FIG. 5 (b-1) are front views of the lens barrel of the present invention, respectively in BB and CC of FIG. 5 (a-1) and FIG. 5 (b-1). FIG. 5 (a-2) and FIG. 5 (b-2) are cross-sectional views of FIG. 5 (a-1) and 5 (a-2) are diagrams when the lens holder is stopped, and FIGS. 5 (b-1) and 5 (b-2) are diagrams when the lens holder is moved. It is.

  Reference numeral 501 denotes a lens, and reference numeral 502 denotes a lens holder that holds the lens 501. Reference numeral 504 denotes a lead screw that is attached to the lens holder 502 via a holder 503. The holder 503 and the lens holder 502 are coupled to each other so as to move integrally in the lens holder moving direction and be relatively movable in a plane perpendicular to the lens holder moving direction. A motor 505 is a power source that rotationally drives the lead screw 504. By driving the motor 505 and rotating the lead screw, the lens holder 502 moves in the optical axis direction. A permanent magnet 506 is attached to the lens holder, and the tip 506a of the permanent magnet 506 is V-shaped. The permanent magnet 506 has an N pole on the optical axis side. The components 501 to 506 are housed in a housing 507. A V-shaped groove is provided at a part of the housing 507, specifically, at a position facing the permanent magnet 506 attached to the lens holder 502, and at a zoom stop point (for example, a wide position, a tele position, etc.) of the lens holder 502. 507a is cut off.

  Reference numeral 511 denotes a permanent magnet, which is disposed at a position facing the permanent magnet 506 attached to the lens holder 502. The permanent magnet 511 is attached to the shaft 513 of the motor 512.

  Operations related to the present embodiment will be described.

  As shown in FIG. 5 (a-2), the permanent magnet 511 attached to the motor 512 at the time of shooting has an N pole on the side facing the optical axis, so in this state, the permanent magnet 511 and the lens holder The attached permanent magnet 506 is attracted by the magnetic force. Further, the V-shaped tip 506a of the permanent magnet 506 fits in the V groove 507a of the housing and is fixed securely.

  Next, when a zoom operation is performed by the photographer, the motor 512 is reversed, and the permanent magnet 511 has an S pole on the optical axis side (FIG. 5 (b-2)), and is attached to the permanent magnet 511 and the lens holder. The permanent magnet 506 repels and the lens holder 502 is lifted. As a result, the tip 506a of the permanent magnet 506 is disengaged from the V groove 507a of the housing, and the lens holder 502 can be moved in the optical axis direction by driving the motor 505.

1 is a front view of a lens barrel according to a first embodiment of the present invention. 1 is a cross-sectional view of a lens barrel according to a first embodiment of the present invention. FIG. 5 is a cross-sectional view of a lens barrel according to a first modification of the present invention. FIG. 4 is a cross-sectional view of a lens barrel according to a second embodiment of the present invention. FIG. 6 is a front view and a sectional view of a lens barrel according to a third embodiment of the present invention. It is the front view and side view of a lens barrel in a conventional example.

Explanation of symbols

101 lens
102 Lens holder
103,104 bar
105 Lead screw
106 motor
107 racks
108 Elastic member
109 housing
110, 111 permanent magnet
121 Plunger
122 Moving parts
123 coil spring
210 Magnetic material
211 electromagnet
501 lens
502 Lens holder
503 Holder
504 lead screw
505, 512 motor
506,511 Permanent magnet
507 chassis
513 axes

Claims (8)

  The lens includes a lens, a lens holder for holding the lens, a driving means for moving the lens holder in the optical axis direction, and a driving device having a magnet and a magnetic body. Has a means to attach a magnet or a magnetic material, strengthen the magnetic force acting between the magnet and the magnetic material when the lens holder is stopped, and weaken the magnetic force acting between the magnet and the magnetic material when moving the lens holder Lens barrel.   2. The lens barrel according to claim 1, wherein permanent magnets are disposed on both the casing and the lens holder.   3. The lens barrel according to claim 2, further comprising a magnet interval changing mechanism that changes an interval between the housing-side permanent magnet and the lens holder-side permanent magnet when the lens holder is stopped and when the lens holder is moved.   2. The lens barrel according to claim 1, wherein an electromagnet is disposed in the housing and a magnetic body is disposed in the lens holder, and a current supplied to the electromagnet is changed when the lens holder is stopped and moved.   A permanent magnet is attached to both the housing and the lens holder, and a magnetic force change mechanism is provided that relatively changes the direction of the magnetic field lines on the housing side and the direction of the magnetic field lines on the lens holder side when the lens holder is stopped and moved. 2. The lens barrel according to claim 1, wherein:   When the lens holder is stopped, the casing-side permanent magnet is driven by the magnet interval changing mechanism, and the interval between the casing-side permanent magnet and the lens holder-side permanent magnet is narrowed. When the lens holder is moved, the casing-side permanent magnet and the lens holder-side permanent magnet are 4. The lens barrel according to claim 3, wherein a gap between the magnets is widened.   When the lens holder is stopped, the current to be applied to the electromagnet is increased so that the magnetic material disposed on the electromagnet and the lens holder is attracted. When the lens holder is moved, the current to be supplied to the electromagnet is decreased to reduce the current. 5. The lens barrel according to claim 4, wherein no magnetic force acts on the magnetic body disposed on the lens holder.   When the lens holder is stopped, the permanent magnet on the housing side is rotated so that the permanent magnet attached to the housing and the permanent magnet attached to the lens holder are attracted. When the lens is moved, the permanent magnet on the housing side is rotated. 6. The lens barrel according to claim 5, wherein the permanent magnet attached to the housing and the permanent magnet attached to the lens holder are repelled.

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