JPH10227961A - Lens part for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel having nearly the same diameter as the conventional lens barrel and to use a plastic lens having a nearly equal effective aperture to a glass lens by attaching the plastic lens to the object-side end face of the lens barrel. SOLUTION: The lens barrel 1 is fixed inside a base plate 11 in a state where a male helicoid screw threaded on the outside surface part of the lens barrel 1 is screwed with a female helicoid screw threaded on the inner wall surface of the plate 4. The part near the circumference of the plastic lens 5 is attached to the object-side end face 1c of the lens barrel 1 by adhesion, a recessed part is formed at the object-side edge of the outside surface part of the lens barrel 1, and a groove part is formed by a projecting part 1b and the lens 5. Then, a focusing ring 8 is fit in the groove part in a state where the projection part 3b of a distance ring 3 is engaged with the notch of the engaging part 8a of the ring 8. In such a case, the glass lenses 6 and 7 are inscribed inside the lens barrel 1 from the object side and attached by the adhesion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens section of a camera having a lens barrel to which a photographing lens group including a plastic lens is attached.

[0002]

2. Description of the Related Art Conventionally, a lens portion of a camera provided with a lens barrel to which a photographing lens group composed of a glass lens is attached has a structure as shown in FIG. FIG. 4 is a cross-sectional view showing an example of the structure of a lens unit in a conventional camera. In the figure, 31 is a lens barrel, 32 is an upper substrate, 33 is a distance ring, 34 is a base plate, 35, 36, and 37.
Is a glass lens, and 38 is a focusing ring. Lens barrel 3
Reference numeral 1 denotes a substantially cylindrical shape, and a glass lens 3
5, 36 and 37 are attached. And the lens barrel 3
A groove 31a is formed on the outer surface of the object 1 on the subject side, and the focus adjustment ring 38 is fitted into the groove 31a.

[0003]

The lenses used in the photographing lens group of the lens portion of the conventional camera shown in FIG. 4 are all glass lenses. recently,
Inexpensive and lightweight plastic lenses have been developed as compared to glass lenses, and attempts have been made to use them as lenses for cameras. However, plastic lenses are obtained by molding by pouring the raw resin into the mold. However, since the transferability from the mold is poorer in the radial direction of the lens, as a result, an effective aperture comparable to that of a glass lens is obtained. In such a case, the diameter of the entire plastic lens must be increased. Therefore, when using a plastic lens in the structure of the conventional lens portion shown in FIG. 4, the diameter of the lens barrel 31 must be increased, and as a result, the entire lens portion becomes large. there were. In addition, when the diameter of the lens barrel 31 is increased, it is difficult to secure a space for fitting a focus adjustment ring provided as a groove 31a near the front end of the lens unit.

An object of the present invention is to use a plastic lens having a lens barrel having a diameter substantially equal to that of a conventional lens barrel to which a photographing lens group consisting of only a glass lens is mounted, and having an effective aperture substantially equal to the glass lens. It is another object of the present invention to provide a lens unit of a camera capable of performing the above-described operations, and further to provide a lens unit capable of sufficiently securing a space for providing a member for adjusting a focus such as a focus adjustment ring.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is directed to a camera lens provided with a lens barrel to which a photographing lens group including a plastic lens is attached. Wherein the plastic lens is attached to an object-side end face of the lens barrel.

According to the lens portion of the camera according to the first aspect, the lens is not attached to the inner surface of the lens barrel by bonding the peripheral portion of the lens or the like as in a conventional lens barrel. Since the plastic lens is attached to the object-side end surface of the lens barrel, a portion of the lens near the circumference of the camera body-side surface can be used when attaching the lens. In other words, when trying to use a plastic lens having the same effective aperture as the glass lens used conventionally, it is necessary to use a plastic lens whose overall diameter is larger than the glass lens.
Since the peripheral part of the surface that does not contribute to the effective aperture of the plastic lens can be used when mounting it on the lens barrel, there is no need to enlarge the lens barrel. The use of a plastic lens having an effective aperture approximately equal to that of the glass lens can be used for a lens barrel having a small diameter.

According to a second aspect of the present invention, there is provided a lens unit of the camera according to the first aspect, wherein the lens unit includes a focus adjusting member such as a focus adjusting ring, and an object on an outer surface of the lens barrel. A recess is provided in the vicinity of the side end, and the recess forms a groove with the plastic lens so that the focus adjusting member can be fixed.

According to the second aspect of the present invention, a plastic lens having an effective aperture substantially equal to that of a glass lens can be used for a lens barrel having a conventional diameter, and the outside of the lens barrel can be used. A concave portion is provided in the vicinity of the object side end of the surface portion, and since the concave portion forms a groove with a plastic lens so that the focus adjusting member can be fixed, a focus adjusting ring or the like is formed. Space for providing the focus adjusting member can be secured.

According to a third aspect of the present invention, there is provided a lens unit of the camera according to the first aspect, wherein the lens unit includes a focus adjusting member, and a lens barrel side end of an outer surface of the plastic lens. There is a recess in the vicinity,
The concave portion forms a groove with the lens barrel so that the focus adjusting member can be fixed.

According to the third aspect of the present invention, a plastic lens having an effective aperture substantially equal to that of a glass lens can be used for a lens barrel having a conventional diameter, and the outside of the plastic lens can be used. A concave portion is provided near the end of the surface portion on the lens barrel side. The concave portion forms a groove with the lens barrel so that the focus adjusting member can be fixed. The space for providing the focus adjusting member can be secured.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a lens section of a camera according to the present invention will be described below with reference to FIGS.

(First Embodiment) First, the configuration will be described. FIG. 1 is an exploded perspective view showing a schematic configuration of main parts of a lens unit of a camera to which the present invention is applied. FIG.
FIG. 2 is a cross-sectional view illustrating main components of a lens unit of the camera in FIG. 1. 1 and 2, 1 is a lens barrel, 2 is an upper substrate, 3 is a distance ring, 4 is a ground plate, 5 is a plastic lens, 6 and 7 are glass lenses, and 8 is a focus adjusting ring (focus adjusting member). In this case, the lens unit is constituted by these components.

The lens barrel 1 has a substantially cylindrical shape, and its inner surface is hollow for mounting glass lenses 6 and 7. Also, on the outer side near the camera body,
A male helicoid screw 1a screwed into the inner wall surface of the cylindrical portion 4a of the main plate 4 is cut. The lens barrel 1 can be moved in the front-rear direction while being rotated by turning the male helicoid screw 1a in parallel with the optical axis of the photographing lens group.
Further, a protrusion 1b is provided in the vicinity of the object side end of the outer surface of the lens barrel 1, whereby a concave portion is formed at the object side edge of the outer surface of the lens barrel 1.

The upper substrate 2 is formed in a disk shape having an opening 2a, and a distance ring guiding portion 2b surrounded by an arc at the top and bottom for inserting a projection 3b of a distance ring 3 to be described later is opened. doing. Also, screwing projections 2c, 2c (not shown) with which the screw 9 is engaged when screwing the base plate 4 are provided.

A gear 3a is formed on a part of the outer periphery of the distance ring 3 to engage with a drive gear (not shown) driven by an autofocus mechanism on the camera body side. Further, a projection 3b is formed on a part of the outer periphery of the distance ring 3.

The base plate 4 is formed in a disk shape having an opening, and the outer surface is formed in a two-step shape of a first step portion 4b and a second step portion 4c at the edge of the opening on the subject side. A cylindrical portion 4a is provided. A female helicoid screw 4d screwed with the male helicoid screw 1a of the lens barrel 1 is cut on the inner wall surface of the cylindrical portion 4a. The disk portion of the base plate 4 is provided with screw holes 4e, 4e (not shown) into which the screws 9 are fitted.

In the photographing lens group of the lens section, the plastic lens 5 is a negative meniscus lens, the glass lens 6 is a plano-convex lens, and the glass lens 7 is a positive meniscus lens, and the optical axes of these lenses coincide. Then, the light of the subject image that has entered the plastic lens 5 passes through the glass lenses 6 and 7 and reaches a photographic film in a camera body (not shown).

A focus adjustment ring 8 as a focus adjustment member is
An engagement portion 8 a having a notch is formed integrally with the focus adjustment ring 8 in a part of the ring.

These parts are assembled in a state as shown in FIG. That is, the distance ring 3 is fitted into the first step portion 4b of the two steps provided on the outer periphery of the cylindrical portion 4a of the main plate 4 so as to be rotatable. From above, the upper substrate 2 is attached to the second step portion 4c. At this time, the projection 3b of the distance ring 3 protrudes from the distance ring guiding portion 2b of the upper substrate 2, and the gear 3a is engaged with a drive gear (not shown). The positions of the upper substrate 2 and the distance ring 3 are determined so as to match. In this state,
The base plate 4 and the upper substrate 2 are fixed by screws 9. The lens barrel 1 is fixed inside the main plate 4 in a state where the male helicoid screw 1a cut on the outer surface of the lens barrel 1 and the female helicoid screw 4d cut on the inner wall surface of the main plate 4 are screwed together. A portion near the circumference of the plastic lens 5 is attached to the end face 1c of the lens barrel 1 on the subject side by bonding. Since the lens barrel 1 is provided with a protrusion 1b, thereby forming a concave portion on the object side edge (near the object side end) of the outer side surface of the lens barrel 1, as shown in FIG. So that the protrusion 1b
And the plastic lens 5 will form a groove. Then, with the projection 3b of the distance ring 3 engaged with the notch of the engagement portion 8a of the focus adjustment ring 8, the focus adjustment ring 8 is fitted into the groove. Glass lenses 6 and 7 are inscribed inside the lens barrel 1 from the subject side, and are attached by bonding.

The entire lens section is attached to the front of the camera body (not shown) integrally with the camera body or in a detachable state.

The operation of the camera having the above-described configuration at the time of photographing the lens unit will be described below.

When the photographer half-presses a release button provided on the camera body, an in-focus position of the photographing lens group (in accordance with the distance from the camera to the subject) is determined by an AF mechanism built in the camera body. A position at which the light of the subject image passing through the taking lens group is focused on the photographic film) is obtained. According to the result, the AF motor in the AF mechanism is driven by a predetermined amount, and the amount of rotation is transmitted to the above-mentioned drive gear via the AF coupler, and the distance ring 3 engaged with the drive gear is moved by a predetermined amount. It will rotate by an angle. And
The focus adjustment ring 8 engaged with the projection 3b of the distance ring 3 by the engagement portion 8a also rotates by the same angle. Since the focus adjustment ring 8 is fixed to the lens barrel 1, the rotation of the focus adjustment ring also rotates the lens barrel 1, but the lens barrel 1 is screwed to the main plate 4 by the male helicoid screw 1 a. The lens barrel 1 moves in the front-rear direction while rotating by the same angle as the focus adjustment ring 8, and the photographing lens group in the lens barrel 1 is located at the above-mentioned in-focus position.

For example, when focusing on an object located closer, the distance ring 3 rotates clockwise (FIG. 1).
(In the direction of arrow A), whereby the focusing ring 8 and the lens barrel 1 also rotate clockwise. Then, the lens barrel 1 moves forward while being fed from the main plate 4 while rotating. Conversely, when focusing on an object located at a farther position, the distance ring 3 rotates counterclockwise (in the direction of arrow B in FIG. 1), and the focus adjustment ring 8 and the lens barrel 1 also rotate counterclockwise. Rotate. Then, the lens barrel 1 rotates and moves backward while being drawn into the main plate 4.

According to the lens portion of the camera of the present invention described above, since the portion near the circumference of the plastic lens 5 is attached to the end surface 1c of the lens barrel 1 on the subject side by bonding, only the conventional glass lens is used. It is possible to use a plastic lens having an effective diameter substantially equal to that of the glass lens and a large overall diameter as the lens closest to the subject on a lens barrel having the same diameter as the lens barrel to which the photographing lens group made of is attached. It becomes possible.

Further, a projection 1b is provided on the outer surface of the lens barrel 1 on the subject side, and a concave portion is formed on the object side edge of the outer surface of the lens barrel 1; 1b and the plastic lens 5 form a groove. Therefore, the focus adjustment ring 8 can be fitted into the groove, and a space for providing the focus adjustment ring 8 can be secured.

(Second Embodiment) FIG. 3 is a cross-sectional view of main parts showing another example of the lens unit of the camera of the present invention. 1 and 2 are denoted by the same reference numerals, and description thereof will be simplified.

The lens barrel 11 shown in FIG. 3 is the same as the lens barrel 1 shown in FIGS.
The structure is almost the same as that described above, except that no protrusion is provided on the outer side surface of the lens barrel 11 to form a concave portion on the edge thereof. Also, the plastic lens 1 shown in FIG.
0 has the same optical characteristics as the plastic lens 5 of FIGS. 1 and 2 except that a concave portion 10 is provided near the end of the outer surface of the plastic lens 10 on the lens barrel 11 side.
a is provided. When assembling the parts, the plastic lens 10 is attached to the end surface 11a of the lens barrel 11 on the subject side.
Are attached by bonding. As a result, as shown in FIG. 3, a groove is formed by the concave portion 10a of the plastic lens 10 and the end surface 11a of the lens barrel 11, and the focusing ring 8 is fitted into the groove. The operation of the lens unit of the camera of the present invention having the above-described configuration at the time of shooting is exactly the same as the operation of the lens unit of the camera of FIGS. 1 and 2. The lens barrel 11 to which the photographing lens group including 10 is fixed also moves in the front-rear direction while rotating, and the photographing lens group is positioned at the in-focus position.

According to the lens portion of the camera of the present invention described above, since the portion near the circumference of the plastic lens 10 is attached to the end surface 11a of the lens barrel 11 on the subject side by bonding, only the conventional glass lens is used. It is possible to use a plastic lens having an effective diameter substantially equal to that of the glass lens and a large overall diameter as the lens closest to the subject on a lens barrel having the same diameter as the lens barrel to which the photographing lens group made of is attached. It becomes possible.

Since a concave portion 10a is provided in the outer surface of the plastic lens 10 near the end on the lens barrel 11 side, a groove is formed by the concave portion 10a and the lens barrel 11. Therefore, the focus adjustment ring 8 can be fitted into this groove, and the focus adjustment ring 8
Can be secured.

In the first and second embodiments, the camera has an autofocus mechanism.
The present invention is not limited to this, and may be a type of camera in which the user sets the distance by himself and adjusts the focus of the photographing lens group. In this case, when the user himself operates the distance ring according to the distance to the subject, the focus adjustment ring rotates the lens barrel in the same manner as in the above embodiment.

Further, the configuration of the camera body of the present invention and the detailed structure including the specific size and shape of each part of the lens unit are arbitrary, and can be changed as appropriate.

[0032]

As described above, according to the lens unit of the camera according to the first aspect, the lens barrel having the same diameter as the conventional lens barrel to which the photographing lens group including only the glass lens is attached is provided. Thus, it becomes possible to use a plastic lens having an effective aperture substantially equal to that of the glass lens.

According to the lens portion of the camera according to the second aspect, it is possible to use a plastic lens having a lens barrel having a diameter substantially equal to that of a conventional lens barrel and having an effective aperture substantially equal to a glass lens. In addition, a sufficient space for providing a member for adjusting the focus such as a focus adjustment ring can be secured.

According to the lens portion of the camera according to the third aspect, it is possible to use a plastic lens having a lens barrel having a diameter substantially equal to that of a conventional lens barrel and having an effective aperture substantially equal to a glass lens. In addition, a space for providing a member for adjusting a focus such as a focus adjustment ring can be sufficiently secured.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a schematic configuration of main parts of an example of a lens unit of a camera to which the present invention is applied.

FIG. 2 is a sectional view showing main components of a lens unit of the camera of FIG.

FIG. 3 is a cross-sectional view illustrating main components of another example of a lens unit of a camera to which the present invention is applied.

FIG. 4 is a cross-sectional view showing main components of a lens unit of a conventional camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens barrel 2 Upper substrate 3 Distance ring 4 Main plate 5 Plastic lens 6 Glass lens 7 Glass lens 8 Focusing ring 10 Plastic lens 11 Lens barrel

Claims (3)

[Claims] 1. A lens unit of a camera including a lens barrel to which a photographing lens group including a plastic lens is attached, wherein the plastic lens is attached to an object-side end surface of the lens barrel. Characteristic camera lens. 2. The method according to claim 1, wherein the lens unit includes a focus adjusting member, and a concave portion is provided near an object side end of the outer surface of the lens barrel. The concave portion fixes the focus adjusting member. The lens part of the camera according to claim 1, wherein a groove is formed together with the plastic lens so as to be able to be formed. 3. The plastic lens according to claim 1, wherein the lens portion includes a focus adjusting member, and a concave portion is provided near an end on the lens barrel side of the outer surface portion of the plastic lens, wherein the concave portion fixes the focus adjusting member. The lens part of the camera according to claim 1, wherein a groove is formed together with the lens barrel so that the lens barrel can be formed.