JP2535066Y2 - Camera pressure plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure plate used in a camera, and more particularly to a pressure plate formed of plastic.

(Prior Art) Conventionally, in a camera, a pressure plate for positioning a film to be exposed to a predetermined position from a photographing lens and matching a focal position of a shutter image with a film position is provided on a rear lid. The pressure plate has a flat surface in contact with the film and is made of a metal such as aluminum.

However, as needs for weight reduction of the entire camera and reduction of manufacturing cost are increased, the material of the pressure plate is gradually changed from metal such as aluminum to plastic, and at present, a pressure plate made of plastic is mostly used.

By the way, in recent cameras, a data module for imprinting data such as date and characters on a shutter image is provided on a rear lid. In order to match a focal position of a data image from this data module with a film position. In addition, it is necessary to reduce the thickness of the pressure plate.

Therefore, in the pressure plate made of plastic, a plurality of pressure plates formed in a planar shape are provided on one surface of the film contact side so that the flatness of the contact surface with the film can be improved even if the plate thickness is reduced. Spherical projections are formed.

Here, the shape of the conventional spherical projection of the pressure plate will be described with reference to FIG. 4. Referring to FIG. 4, a plurality of conventional spherical projections 11, 11, and Have a substantially semicircular side surface, and the pressure plate 10 on which the spherical projections 11, 11,... Are usually formed by molding such as injection molding using a mold. .

(Problem to be Solved by the Invention) In the conventional pressure plate 10 described above, the plane portion M of the pressure plate 10
Are large (generally about 20 °) between the tangent line N at the starting point of the spherical projections 11, 11, and so on, so that the above-described configuration in a mold (not shown) for manufacturing the pressure plate 10 by injection molding or the like is used. The bend angle at the starting point of the spherical projections 11, 11,... Becomes acute.

For this reason, the fluidity of the plastic material in the mold at the bent portion is deteriorated, and the inflow pressure of the plastic material into the spherical protrusion on the mold side is reduced, so that the spherical protrusion on the mold side is reduced. Bubbles are mixed in or the flow of the plastic material is insufficient.
Wrinkles and rough surfaces may occur in the ten spherical projections 11, 11,....

Then, when winding up the film positioned by the pressure plate 10, the spherical projections 11, 11, and
In order to prevent this, there is a problem that the surface on the side where… comes into contact is damaged. There was a problem that there was.

Also, since the spherical projections 11, 11,... Of the conventional pressure plate 10 are substantially semicircular on the side surface, the radius value thereof cannot be increased, so that the contact area with the film becomes small, and the spherical projections 11, 11,. ... There was a problem that the load per contact increased.

The present invention has been made in view of the above circumstances, and can prevent the occurrence of wrinkles and rough surfaces on the spherical projections of the pressure plate during molding, and can prevent the surface of the film from being damaged. It is another object of the present invention to provide a camera pressure plate capable of reducing the load per spherical projection.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a pressure plate having a plurality of spherical projections formed on one surface of a flat plate, and a flat portion of the pressure plate and a starting point of the spherical projection. The angle α between the tangent and the tangent is within the range of 10 ° ≦ α ≦ 15 °.

Further, in the present invention, the height h of the spherical projection as viewed from the plane portion of the pressure plate is in the range of 0.05 mm ≦ h ≦ 0.08 mm.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing the shape of a spherical projection on a camera pressure plate according to one embodiment of the present invention, FIG. 2 is a plan view showing the camera pressure plate according to one embodiment of the present invention, and FIG. FIG. 4 is an explanatory view of relevant parts showing a state where the pressure plate of the camera shown in FIG.

As shown in FIG. 2, a plurality of spherical projections 21, 21,... Are formed on one surface of the pressing plate 20 on the side of contact with a film (not shown). The guide rails 22, 22 are formed as shown in FIG.

In this embodiment, the pressure plate 20 shown in FIG.
The length t of the plane portion P is 1.3 mm, the angle α formed by the plane portion P of the pressure plate 20 and the tangent S at the starting point of the spherical projections 21, 21,. The height h of the spherical projections 21, 21,... As viewed from the plane portion P is 0.07 mm.

On the other hand, the rear cover 2 of the camera body 1 to which the pressure plate 20 is attached
Each of the upper and lower edges has a holding piece 3 having a substantially L-shaped side surface, and a pressing spring 4 is disposed on the inner surface thereof. The pressure plate 20 is positioned and mounted on the rear lid 2 of the camera body 1 by pressing the surface side to press the guide rails 22 and 22 against the holding piece 3.

When the pressure plate of the camera according to the present embodiment having the above configuration is formed by molding such as injection molding, for example, the angle α formed by the plane portion P of the pressure plate 20 and the tangent S at the starting point of the spherical projections 21, 21,. , So that spherical projections 21, 21,... Inside a mold (not shown) used for molding the pressure plate 20 are provided.
Of the plastic material at the bent portion of the mold is improved.

Then, the inflow pressure of the plastic material in the portion where the spherical projections 21, 21,... Of the mold are formed increases, and the insufficient inflow of the plastic material in the bubbles in this portion is eliminated.
The generation of wrinkles and rough surfaces on the molded product side, that is, on the spherical projections 21, 21,... Of the pressure plate 20 is prevented.

For this reason, it is possible to prevent the film surface from being damaged when the film is wound up without newly applying mirror finishing or the like to the spherical projections 21, 21,... After forming the pressure plate 20.

Also, spherical projections 21, 21, viewed from the plane portion P of the pressure plate 20,
Are set to 0.07 mm, the radius of the spherical projections 21, 21,... On the pressure plate 20 is increased, and the contact area with the film is increased, so that the spherical projections 21, 21,.
... The load per contact can be reduced.

Although the embodiment has been described with reference to the case where a spherical projection is formed on one surface of the pressure plate, the present invention is also applicable to a projection such as a rib.

(Effects of the Invention) As described above, according to the present invention, the angle α formed by the flat portion of the pressure plate and the tangent at the starting point of the spherical projection is within the range of 10 ° ≦ α ≦ 15 °. Because it was
The fluidity of the plastic material at the starting point of the spherical projection inside the mold used for press plate molding is improved.

For this reason, it is possible to prevent the formation of wrinkles and rough surfaces on the molded product side, that is, on the spherical projections of the pressure plate, and thus, the spherical projections of the molded pressure plate can be prevented from being subjected to mirror finishing or the like. Of the film can be increased so as not to damage the film.

Further, the height h of the spherical projection as viewed from the plane portion of the pressure plate
Is set to be in the range of 0.05 mm ≦ h ≦ 0.08 mm, so that the radius value of the spherical projections increases and the contact area with the film increases, so that the load per each spherical projection is reduced. Can be.

[Brief description of the drawings]

FIG. 1 is a side view showing the shape of a spherical projection on a camera pressure plate according to one embodiment of the present invention, FIG. 2 is a plan view showing the camera pressure plate according to one embodiment of the present invention, and FIG. And FIG. 4 is a side view showing the shape of a spherical projection on a conventional camera pressure plate, with the camera pressure plate shown in FIG. In the drawing, reference numeral 20 denotes a pressure plate, and reference numeral 21 denotes a spherical projection.

Claims (2)

(57) [Scope of request for utility model registration] 1. A pressure plate having a plurality of spherical projections formed on one surface of a flat plate, wherein an angle α formed by a plane portion of the pressure plate and a tangent at a starting point of the spherical projection is 10 ° ≦ α ≦ 15 °. A pressure plate for a camera, wherein: 2. The camera pressure plate according to claim 1, wherein a height h of the spherical projection as viewed from a plane portion of the pressure plate is in a range of 0.05 mm ≦ h ≦ 0.08 mm.