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Lens barrel

A lens barrel and lens group technology, applied in the field of lens barrels, can solve problems such as difficulty in obtaining a stable image at the farthest focus point, low precision, and hysteresis characteristics

Inactive Publication Date: 2001-05-09
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the excitation control of the stepping motor is open-loop, there are the following problems: low accuracy at the stop position; hysteresis characteristics; relatively few rotations; and the like
Therefore, a system consisting of a small and lightweight lens barrel, a stepping motor with an encoder, and a linear actuator cannot achieve high-speed responsiveness and low power consumption in driving zoom and focus lenses
[0009] (2) The small, lightweight and high-magnification lens barrel poses a problem that hand vibration makes it difficult to obtain a stable image at the farthest focus point
[0012] (3) As shown in question (1), when a stepper motor with an encoder is used as zoom and focus actuators respectively, magnetic flux leaks from two shift actuators for image vibration compensation , which negatively affects the magnetic sensor

Method used

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Experimental program
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Embodiment 1

[0060] A lens barrel according to Embodiment 1 of the present invention will be described below by referring to FIGS. 1 to 6 . 1 is a schematic perspective view of a lens barrel according to Embodiment 1 of the present invention, which includes a linear actuator and a stepping motor. Figure 2 is a schematic diagram of the principle of a beam of magnetic flux leaking from the lens barrel. Fig. 3 is a graph showing a magnetoresistance change characteristic of an MR element. Fig. 4 is a schematic perspective view of a position detecting section equipped with an MR element. Figure 5 is a simplified schematic diagram of a beam of magnetic flux leaking onto a stepper motor with an encoder. Figure 6 is a schematic diagram of the principle of a beam of magnetic flux leaked to the magnetic sensor according to Embodiment 1 of the present invention.

[0061] A focus lens moving frame 31 holds a focus lens group 30 which are directed in parallel to an optical axis. The focus lens movi...

Embodiment 2

[0082] The first lens group for compensating for image vibration when taking images is fixed on a holder 2 that can move along the Z direction shown in FIG. 7 . Hereinafter, the cage 2 is referred to as a pitching frame 2 . By installing a support 2a and a lock pin 2b on the opposite side of the support 2a, the pitch moving frame 2 can smoothly move through the two pitch axes 3a and 3b. An electromagnetic actuator 6p is also housed below the pitching mobile frame 2 .

[0083] The electromagnetic actuator 6p includes a coil 7p fixed on the pitch moving frame 2, a magnet 8p and a yoke 9p mounted on the fixed frame 10 as described later. The opposite sides of the yoke 9p have projections 9pa. The fixing frame 10 is provided with engaging holes 10pa capable of engaging the projections 9pa, and they are arranged substantially parallel to the direction in which the tilting movable frame 2 moves smoothly. Thus, the yoke 9p is fixed to the fixing frame 10 without adhesive or the ...

Embodiment 3

[0098] Next will refer to Figures 10 to 13 A third embodiment of the present invention will be described. Figure 10 is a schematic perspective view of a lens barrel according to Embodiment 3 of the present invention, which includes an image vibration compensating device and a linear actuator. Fig. 11 is a schematic structural view of a yoke in a linear actuator. Figure 12 is a simplified diagram of a beam of magnetic flux of a magnet in a displacement actuator of an image vibration compensation device. Figure 13 is a simplified diagram of a beam of magnetic flux of the magnet in the linear actuator according to Embodiment 3 of the present invention. The components described above are denoted by the same reference numerals, and their descriptions are omitted.

[0099] The shift unit 20 in Embodiment 3 is the same as that described in Embodiment 2. For simplicity, the fixing frame 10 of the displacement unit 20 is omitted in FIG. 11 . The pitch magnet 8p, the swing magn...

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Abstract

A lens barrel comprising a first lens group, a second lens group, a third lens group, a first actuator for driving the first lens group, a second actuator for driving the second lens group, and third and fourth actuators for driving the third lens group, wherein at least one of the first to fourth actuators is disposed in a position where the leakage flux from at least one of the first to fourth actuators is cancelled.

Description

technical field [0001] This invention relates to lens barrels for use in video cameras or the like. Background technique [0002] Recently, there has been a demand for a small lens barrel in a video camera that has been downsized. In addition, fast zooming and focusing are also required. [0003] A conventional lens barrel will be described below. [0004] Typically, there are four lens groups contained in a camera lens barrel. The movable lens barrel among the four lens barrels can be guided to move in an optical axis direction along a guide post for zooming and focusing. The lens barrel includes a fixed lens group, a lens group that can move on the zoom optical axis, another fixed lens group, a lens group that can move on the focusing optical axis, an aperture unit and an imaging plane. The zoom lens group and the focus lens group are held by the zoom lens holder and the focus lens holder, respectively. The zoom actuator and the focus actuator for driving the zoom len...

Claims

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Application Information

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IPC IPC(8): G02B7/10
CPCG02B7/102
Inventor 弓木直人林孝行高桥裕
Owner PANASONIC CORP
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