JP3144758B2 - Dustproof device for camera with variable focus lens device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera provided with a variable focal length lens device capable of changing a focal length by moving a taking lens in the direction of an optical axis. The present invention relates to a dustproof device for preventing such a situation.

[0002]

2. Description of the Related Art In order to easily enjoy taking a picture, a camera using a see-through finder having a variable focal length lens device capable of changing a focal length without changing a photographing lens has become widespread. The variable focus lens device mounted on this type of popular camera mainly includes a so-called bifocal switching type in which the focal length of a photographing lens can be switched between a wide-angle side or a standard side and a telephoto side, and There is a zoom lens type in which the focal length of the lens can be continuously changed from the wide-angle side or the standard side to the telephoto side. Each of the variable focus lens devices includes a movable lens that moves forward and backward in the optical axis direction, and has a structure in which the movable lens is moved when the focal length is changed. In addition,
If necessary, a converter lens that retracts on the optical axis is provided, and this converter lens is retracted in the optical axis when the moving lens moves forward or backward. A structure is adopted in which the lens is also moved in the optical axis direction so that the moving lens and the fixed lens maintain a predetermined optical relationship.

A structure for moving a movable lens in a conventional camera with a variable focus lens device of this type includes a lens which is fixed with respect to the movable lens and which is rotatable about an optical axis. A structure in which a movable lens is held by a fixed lens barrel supported by a main body and a movable lens is held by a movable lens barrel slidable in the optical axis direction with respect to the fixed lens barrel is mainly employed. ing. Then, a cam hole of an appropriate shape is formed on the side surface of the fixed-side lens barrel, and an engaging pin that is loosely inserted into the cam hole is protruded from the outer surface of the movable-side lens barrel. And the engaging pin is engaged with the cam hole. Therefore, when the fixed-side barrel rotates about the optical axis, the cam hole rotates about the optical axis, and the engagement pin moves along the optical axis guided by the cam hole. Moves to change the focal length.

FIGS. 5 and 6 are schematic longitudinal sectional views of a central portion for explaining movement of a movable barrel of a conventional camera with a variable focal length lens device. FIG. 5 is a movable mirror holding a movable lens 1. FIG. 6 shows a state in which the front of the camera casing 3 coincides with the front of the movable barrel 2 when the barrel 2 is retracted. , Respectively, project from the front surface of the camera casing 3. That is, in the conventional camera with a variable focal length lens device, the movable lens barrel 2 moves in the optical axis direction with respect to the camera casing 3 so that the focal length is changed. 5 and FIG.
Reference numeral 5 denotes a fixed lens, and reference numeral 5 denotes an image forming surface such as a film surface or a CCD.

[0005]

However, in the above-described conventional camera with a variable focal length lens device, the movable lens barrel has a structure in which the movable lens barrel advances and retreats with respect to the camera casing.
There are the following problems. Since the movable barrel is inserted into the fixed barrel and is slidable with respect to the fixed barrel, the movable barrel, the fixed barrel, the movable barrel, and the camera casing A slight gap is formed between them. Therefore, the inside and outside of the casing communicate with each other via this gap. Therefore, there is a possibility that dust such as dust or dirt may enter the inside of the camera casing from the gap. Then, dust or the like that has entered the camera casing may enter the inside of the lens barrel and adhere to the lens surface.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dustproof device for a camera with a varifocal lens device which can prevent dust from entering through a gap communicating the inside and outside of a casing.

[0007]

As a technical means for achieving the above object, a camera with a variable focal length lens device according to the present invention moves an appropriate lens constituting a taking lens in the optical axis direction. In the camera provided with the variable focal length lens device that changes the focal length of the photographing lens, the movable lens barrel that holds the movable lens that moves in the optical axis direction is inserted through the front surface of the camera casing. A ring-shaped charging member is provided at the periphery of the hole, a booster circuit is connected to the charging member, and power is supplied from the booster circuit to the charging member at a high voltage.

[0008] The present invention is characterized in that power is supplied to the charging member when the movable barrel is moved or in conjunction with turning on a main switch of the camera.

When a high voltage is supplied from the booster circuit to the charging member, the charging member is charged with static electricity. Since the charging member is provided on the front surface of the casing of the camera and at the periphery of the hole through which the moving lens barrel is inserted, dust on the peripheral surface of the moving lens barrel due to static electricity carried by the charging member. Dust such as dust adheres to the charging member.

The power supply to the charging member can be performed by operating a main switch or a power supply dedicated switch of the camera. However, if the power supply is performed in synchronization with the movement of the movable barrel. This is preferable because it can be activated when dust easily enters the casing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dustproof device for a camera with a variable focus lens device according to the present invention will be specifically described below based on a preferred embodiment shown in the drawings.

FIG. 1 is a schematic longitudinal sectional view for explaining the structure of a camera provided with the dustproof device.
It is sectional drawing cut | disconnected along the A line. The front lens group 11, which is a movable lens, is held by a movable lens barrel 12, and the movable lens barrel 12 advances and retreats in the optical axis direction with respect to the front surface of a casing 13 housing a camera body. Is changed. Note that a rear group lens 14 is located behind the movable lens 11, and an image plane 15 such as a film surface or a CCD is located further behind.

On the front surface of the casing 13 and on the periphery of the hole through which the movable lens barrel 12 is inserted, a charging member made of a synthetic resin such as nylon or a metal such as silver is formed in a substantially annular shape. 21 are arranged. As shown in FIG. 3, the charging member 21 is connected to a power supply 22 via a booster circuit 23, and a high voltage is applied from the booster circuit 23. The power supply 22 may be a power supply battery for a motor for driving, for example, a zoom lens device incorporated in the camera, or a power supply battery for a film feeding motor. A switch 24 is connected to the booster circuit 23,
When this switch 24 is turned on, this booster circuit
23 is activated. Further, this switch 24 may be a switch dedicated to the operation of the booster circuit 23,
If the switch is linked to a main switch of the camera, or preferably to a switch operated when zooming the zoom lens device, it is advantageous in the operation described later.

As shown in FIG. 4, the charging member 21 is provided with four or more electrode plates 25 made of a conductive rubber material or the like at substantially equal intervals. These electrode plates 25 are connected.

The operation of the embodiment of the dustproof device for a camera with a variable focal length lens device according to the present invention constructed as described above will be described below.

When a zoom switch or the like is operated to change the focal length of the photographing lens, the boosting circuit 23 operates to output a high voltage, and the high voltage is applied to the charging member 21 from the electrode plate 25. Will be. As a result, the charging member 21 is charged with static electricity, and dust such as dust and garbage adheres to the charging member 21. This charging member
Reference numeral 21 denotes a front surface of the casing 13 of the camera,
Is disposed at the peripheral edge of the hole through which dust is inserted, so that dust can be prevented from entering the inside of the casing 13 from this hole.

When the switch 24 is turned off and the power supply to the charging member 21 is stopped, the static electricity disappears, and dust and the like attached to the charging member 21 fall. For this reason, it is preferable to keep the surface of the charging member 21 as a smooth surface because dust does not easily fall off the charging member 21 and remain on the front surface of the casing 13.

If the switch 24 is turned on and off in conjunction with the zoom drive switch of the zoom lens device, the switch 24 is synchronized with the movement of the movable lens barrel 12 where dust easily enters the interior of the casing 13. As a result, dust is attached to the charging member 21, so that dust can be efficiently prevented from entering. The zoom lens is driven to move the movable lens barrel 12 to the casing.
Even if dust adheres to the outer peripheral surface of the movable lens barrel 12 in a state where it is protruded from the front surface of the movable member 13, when the movable lens barrel 12 retreats, the charging member 21 magnetizes and attaches the dust. become. Therefore, there is no possibility that dust will be carried into the casing 13 even if the movable lens barrel 12 is retracted.

[0019]

As described above, according to the dustproof device for a camera with a varifocal lens device according to the present invention, the peripheral edge of the hole through which the movable lens barrel is inserted is the front surface of the camera casing. Since a member is provided and a high voltage is applied to the charging member to generate static electricity, dust such as dust around the movable barrel is attached to the charging member. Therefore, it is possible to prevent dust from entering the inside of the casing from the hole.

When a high voltage is applied to the charging member in synchronization with the movement of the movable barrel, dust around the movable barrel adheres when dust and the like are most likely to enter. Therefore, intrusion of dust can be satisfactorily prevented.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a camera with a variable-focus lens device provided with a dustproof device according to the present invention, which is taken along line AA in FIG.
It is sectional drawing cut | disconnected along the line.

FIG. 2 is a schematic front view of a camera with a variable focus lens device provided with the dustproof device.

FIG. 3 is a schematic block diagram illustrating a circuit for driving a charging member.

FIG. 4 is a schematic view of a charging member, and is a perspective view seen from inside a casing of the camera.

FIG. 5 is a view for explaining a moving state of the movable lens barrel, and shows a state in which the movable lens barrel is retracted and accommodated in the camera casing;

FIG. 6 is a view for explaining a moving state of the moving-side lens barrel, and shows a state in which the moving-side lens barrel advances and projects from the camera casing;

[Explanation of symbols]

 11 Front group lens (moving side lens) 12 Moving side lens barrel 13 Casing 14 Rear group lens 15 Imaging surface 21 Charging member 22 Power supply 23 Boost circuit 24 Switch 25 Electrode plate

Claims (3)

(57) [Claims] 1. A camera equipped with a variable-focus lens device for changing a focal length of a taking lens by moving an appropriate lens constituting the taking lens in an optical axis direction, wherein the camera has a front surface of a casing of the camera, An annular charging member is disposed on the periphery of the hole through which the moving lens barrel that holds the moving lens that moves in the optical axis direction is inserted, and a booster circuit is connected to the charging member. A dustproof device for a camera with a variable focus lens device, wherein a high voltage is supplied to the charging member. 2. The dustproof device for a camera with a variable focus lens device according to claim 1, wherein power is supplied to the charging member when the movable barrel moves. 3. The dustproof device for a camera with a variable focus lens device according to claim 1, wherein power supply to the charging member is performed in conjunction with turning on of a main switch of the camera.