JP2005215573A - Lens hood - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent dust, a drop of water, etc., from entering the inside of a cover from a lens front part. <P>SOLUTION: A shape which fills a gap at the television lens front part present between the cover and a lens barrel is formed integrally with a lens hood. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lens hood for a television lens.

  Conventionally, a television lens for a broadcasting station has a lens barrel 1 that holds a photographing optical system as shown in FIG. 4, and a substantially rectangular fixed housing 3 that serves as a member for mounting to a broadcasting television camera. A substantially rectangular cover 2 that matches the shape of the fixed housing is provided outside the lens barrel. The front end portion of the cover shields the upper and lower portions of the lens front lens side as shown in FIG. 5A in order to block harmful light and mask the upper and lower portions that are unnecessary for photographing. In order to protect the edge of the cover at the front portion of the television lens, a lens hood 4 having such a shape as to wrap around the end face of the cover as shown in FIG. As shown in FIG. 6, the cover can be opened / closed and detached by sliding it from the front side direction. It is fixed and contains the lens barrel and the motor used for zooming. In order to facilitate opening and closing and removal, the TV lens is provided with a guide 6, and a guide function is achieved by providing a portion that fits with the guide in the case. Several proposals have been made regarding the structural relationship between the two (for example, JP-A-2000-206588).

  With respect to the lens hood in such a television lens for a broadcasting station, for example, by sliding, it is possible to obtain a desired light-shielding effect in both macro photography and telephoto photography (Japanese Patent Laid-Open No. 8-82831). In order to protect the front of the lens by attaching it to the front end of the cover, many have a substantially rectangular shape according to the shape of the cover. Here, since the lens barrel has a substantially cylindrical shape, there is a gap 2a in the front portion of the lens due to the difference in shape between the two. Foreign matters such as dust and water droplets enter the inside of the cover from this gap, which causes a lens failure.

Therefore, in order to prevent the entry of foreign matter into the cover, a method of sealing between the cover and the lens barrel using a sealing material 7 as shown in FIG. 7, and further dustproof and dripproof properties are required. For those used in an environment where the lens barrel is transparent, use a transparent member, make the case completely box-shaped, and put the lens barrel in it to prevent dust and splash A method of fulfilling this has also been proposed.
JP2000-206588 JP-A-8-82831

However, in order to prevent dust, water droplets and the like from entering the inside of the cover from the front of the lens, the case has a substantially rectangular shape as described above, and the lens barrel Because it has a substantially cylindrical shape and the shape of both is different,
1. In order to apply a constant pressure from both directions in order to make the effect of the sealing material effective, the shape of either the case or the sealing material must be complicated.

It becomes a problem. Also, in a structure that puts the entire lens barrel in a box,
2. The lens barrel is covered with a cover, which complicates the configuration.

  3. The weight on the front side of the TV lens increases, which causes problems in shooting.

It will be said that. Furthermore, because any of these methods will use new parts,
4). Manufacturing costs increase.

The cover is fixed in close contact with the fixed housing at the rear of the lens, but on the front side, it is combined with a guide used as a guide when being mounted, but is restricted between them. Not. For this reason,
5). The cover lacks the restraint on the front side of the lens, and the load on the mounting portion on the back is large.

  6). When the vibration generated from the motor attached to the lens is transmitted, the cover not restrained at the front portion vibrates.

  In relation to 7.6, noise is generated when the cover vibrates, and this noise is recorded during recording.

  It becomes a problem.

  In view of the above, the first object of the present invention is to prevent dust, water droplets, and the like from entering the interior of the cover with a low-cost and simple structure in the television lens for broadcasting stations. It is to be realized. A second object of the present invention is to prevent the generation of noise by restraining the cover on the lens front side and suppressing the vibration of the cover.

  As means for solving the above-mentioned problem, the first invention is that the cover is formed by integrally forming the lens hood with a shape that fills the gap in the front portion of the TV lens existing between the cover and the lens barrel. The structure is to keep the inside sealed, and to get dust and drip proof from the front side.

  According to a second aspect of the present invention, the lens hood is made of an elastic member, and the stability of the cover is improved by elastically supporting the cover and the lens barrel in the vicinity of the front side of the television lens. In addition to improving the shape, the lens hood has a shape having an elastic deformation structure, thereby providing a role of absorbing vibration from a motor or the like inside the television lens.

  The following can be said as an effect of the first invention.

  1. In a television lens for a broadcasting station, an improvement in dustproof and drip-proof properties in front of the television lens can be realized at a low cost by simply changing the shape of the lens hood without adding a new member.

  In relation to 2.1, it is possible to improve the dustproof and dripproof properties with the same simple structure as before, and without having to change the manufacturing process.

  The effects of the second invention can be summarized as follows.

  3. In the TV lens front portion, the lens barrel and the cover are elastically supported, so that the stability of the cover at the lens front portion is improved.

  4). By providing the lens hood with an elastic deformation structure, vibration transmitted from the motor inside the TV lens to the cover can be absorbed, and vibration of the cover can be suppressed.

  In relation to 5.4, noise generated by the vibration of the cover can be suppressed.

  6). In the fitting portion between the lens hood and the lens barrel, the adhesion between them increases, and the dust / drip proof property at the front portion of the lens is further improved.

(Example)
(First embodiment)
FIG. 1 is a sectional view showing an embodiment of the present invention.

  The lens hood 8 has a substantially rectangular shape along the shape of the cover 9 so as to protect the front end of the cover, as in the conventional case, and the lens hood and the cover are bonded to each other at the joint surface 8a. It is fixed and integrated with no gap over the entire circumference. The lens hood also has a shape for performing upper and lower masks that are unnecessary for photographing, but has a shape different from the conventional one, and an annular portion 8b is provided in the rear part so as to fit the lens barrel 10. Yes. Thus, when the cover with the lens hood fixed is slid along the guide and attached, the lens barrel is inserted inside the annular portion of the lens hood, and the two are fitted to each other so as to be in close contact with each other. Alternatively, the tip of the lens barrel can be brought into close contact with the protruding portion 8c of the lens hood. In this state, by fixing the cover to the fixed housing at the rear of the lens, it is possible to fill a gap existing on the front surface of the lens.

With this structure, the gap on the front side of the television lens can be closed without newly introducing parts, and the inside of the cover can be kept sealed. Also, the structure in which the lens hood is integrated with the cover is the same as the conventional one, and the method of sliding the cover from the front side of the lens and fixing it to the fixed housing is the same as the conventional one. There is no need to change the process at the time.
(Second embodiment)

  Further, the lens hood is made of an elastic body, and at the portion where the lens hood and the lens barrel are fitted, an appropriate pressure is applied to the inner side of the lens hood with respect to the outer diameter of the lens hood. By setting to, the degree of adhesion between the lens hood and the lens barrel can be increased, and the dust and drip proof performance can be improved. Further, by providing the groove 8d so that the lens hood is elastically deformed as shown in FIG. 1, the lens barrel and the cover are supported in the vicinity of the front of the lens in a state where an elastic force is applied. As a result, the stability of the cover at the front part of the lens is improved, and vibrations from the motor mounted on the TV lens can be absorbed by the lens hood deforming like a seismic isolation material. The effect which suppresses the vibration transmitted to is acquired. This eliminates the problem of noise from the cover, which has been caused by the vibration of the conventional case.

  The lens barrel and the lens hood are fitted from the inside of the lens barrel as shown in FIG. 2 in addition to the direction in which the lens hood restrains from the outside of the barrel as shown in FIG. A method of making the lens hood hit is also conceivable. Further, as shown in FIG. 3, by providing a groove 8f in a direction perpendicular to the optical axis, an elastic force is generated in the optical axis direction, thereby closing the gap between the lens barrel and the lens hood on the front side of the lens barrel. There is also a method.

A cross-sectional view best representing the features of an embodiment of the present invention The figure which a lens hood hits from the inner side of a lens-barrel among the Example of this invention. The figure which a lens hood hits from the inner side of a lens-barrel among the Example of this invention. A perspective view of a conventional TV lens for a broadcasting station The figure for explaining the role of the lens hood in the television lens for broadcasting stations The figure which shows the attachment method of the cover in the television lens for broadcasting stations Cross-sectional view when sealing material is used in the conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens barrel 2 Cover 3 Fixed housing 4 Lens hood 5 Screw 6 Guide 7 Sealing material 8 Lens hood 9 Cover 10 Lens barrel

Claims (2)

  A substantially cylindrical lens barrel that holds the photographing optical system and a substantially rectangular fixed housing are connected along the optical axis, and the projection area of the substantially rectangular fixed housing is the substantially cylindrical lens barrel. The housing is fixed to the fixed housing by covering the lens barrel and sliding the lens from the front side (front lens side). A lens hood having a substantially rectangular cover, wherein the lens hood is fixed to the cover and is fitted to the lens barrel, or is in close contact with the tip of the lens barrel without any gap.   The television lens according to claim 1, wherein the lens barrel and the cover are supported by an elastic force in the vicinity of the front side of the lens by being made of an elastic material and provided with an elastic deformation structure. The lens hood according to claim 1.

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