JP2623851B2 - Viewfinder optical system with photometric system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a finder optical system having a photometric system suitable for a photographing device such as a still video camera.

(Prior Art) Conventionally, photometry performed by a compact camera has been performed through a photometry window arranged separately from a photographic lens and a finder system. However, in recent years, compact cameras have been made into zoom lenses, so that in the conventional configuration, the parallax of the photometry system on the telephoto lens side becomes large, and the photometry range with respect to the photographing screen greatly changes due to zooming.

In particular, a camera having a small shooting screen such as a still video camera can be configured to have a small shooting lens itself, so that zooming is relatively easy. Therefore, in such a still video camera, the above-mentioned problem becomes remarkable.

Therefore, in a so-called external finder system for performing finder observation at a position different from the photographing system, the finder system is constructed by sequentially ordering the objective concave lens 1, the objective convex lens 2, the objective convex lens 2 from the object side as shown in FIGS. 4 (a) and 4 (b). 1 field lens 3, primary focus surface 4, half mirror 5, total reflection mirror 6 disposed on the reflection side of the half mirror 5, secondary imaging lens 7, second field lens 8, secondary focus surface 9 , An optical member of the eyepiece 10, and a condensing lens 11, a color glass 12,
By arranging the light receiving (light measuring) sensor 13 to constitute the light measuring system, it is possible to eliminate the parallax of the light measuring system and to optimally set the light measuring range for the photographing screen.

An objective lens system capable of zooming is constituted by the objective concave lens 1 and the objective convex lens 2. The objective convex lens 2 moves from the image side to the object side to increase and reduce the magnification, and the objective concave lens 1 corrects the image plane movement accompanying the magnification. The first field lens 3 has a function of condensing the light beam of the objective lens system near the entrance pupil of the secondary imaging lens 7. The secondary imaging lens 7 converts the primary image of the objective lens system formed on the four primary focus surfaces into two.
It has the function of re-imaging on the next focus plane 9. The second field lens 8 has a function of condensing the light flux of the secondary imaging system near the position of the eye to be observed.

The finder system composed of the optical members 1 to 10 of this example is a real image finder system of a secondary imaging system used when the depth of the camera is long, and is a zoom finder obtained by zooming the objective system.

The half mirror 5 has a function of folding the finder optical path in order to reduce the depth dimension of the camera, and a function of partially transmitting the light amount to the photometric system. A photometric system is composed of a photometric condenser lens 11, a colored glass 12, and a light receiving sensor 13 arranged behind the half mirror 5. Condensing lens 11 for photometry detects the image of primary focus surface 4
An image is formed in the vicinity of 12, and a specific part of the viewfinder screen is measured. The photometric system is the first field lens 3
Because it is behind, the surrounding area can be measured without vignetting.

The optical members 11 to 13 of the photometric system are arranged in this order on the optical axis of the transmitted light of the half mirror 5 to the rear of the half mirror, and the half mirror 5, the condensing lens 11 for photometry, and the color glass 12 are shown in FIG.
The light-receiving sensor 13 is fixed to the finder structure (body) 20 as shown in FIG. Then, it is positioned and fitted and fixed to the finder structure 20 by fitting it into a dowel engaging hole 14a provided on the substrate 14 side.

(Problems to be Solved by the Invention) However, the optical system having the above layout has the following problems.

That is, since the constituent optical members 11 to 13 of the photometric system are arranged in the finder front-back direction on the transmitted light optical path of the half mirror 5 in the rear of the half mirror in order, the substrate 14 on which the light receiving sensor 13 is mounted is held. FIG. 4 (b)
As described above, the finder structure 20 is installed and fixed in the finder structure 20 in a vertical posture that is the cross-sectional direction of the finder structure 20. In this case, the cross section of the finder structure is originally small in area, and the area occupied by the substrate 14 in the cross section is further limited, and the designable dimensions of the substrate 14 in both the vertical and horizontal directions are reduced. Limited. Therefore the substrate
As 14, there are problems that it is difficult to secure a sufficient size for stably holding the light receiving sensor 13, and that the assembling and assembling properties in the finder structure 20 are poor. This problem becomes more pronounced as the viewfinder becomes smaller.

An object of the present invention is to solve such a problem.

(Means for Solving the Problems) The gist of the present invention is a finder optical system having a photometric system having the following configuration.

(1) A half mirror for splitting an optical path is arranged between a field lens of an external type finder system and a secondary imaging lens for performing finder observation with a finder system provided independently of a photographing system, and a transmission side of the half mirror. In a finder optical system having a photometric system including a condensing lens and a light receiving sensor for photometry, the transmitted light path of the half mirror, which is a front-rear direction of the finder, is provided in the finder optical system in a direction substantially perpendicular to the optical path. A finder optical system having a photometric system, wherein the light whose optical path has been changed by the reflection surface member enters a light receiving sensor supported on a substrate fixed to a structure.

(2) The light-measuring light-collecting lens and the reflecting surface member of the light metering system are constituted by an integrally formed optical element having a refracting surface portion acting as a condensing lens and a reflecting surface portion acting as a reflecting surface member. A finder optical system having the photometric system according to the above (1).

(3) The finder optical system having the photometric system according to the above (1), wherein a color glass is interposed between the optical element and the light receiving sensor by being adhered and fixed to the optical element.

(4) The finder optical system having a photometric system according to the above (3), wherein one or both of the optical element and the colored glass which are adhered and fixed to each other are provided with mutual positioning means.

(5) The dowel according to any one of (2) to (4), further comprising a dowel and a dowel engaging portion that are positioned relative to the optical element and the light receiving sensor substrate. Viewfinder optical system with photometric system.

(6) A finder optical system having a photometry system, wherein a mutual positioning fitting portion is provided between the optical element and the light receiving sensor and fitted.

(Operation) As described in item (1), the photometric system has an optical member array structure capable of mounting and fixing the support substrate of the light receiving sensor to the finder structure in a lateral posture substantially parallel to the front and rear direction of the finder system. By doing so, the degree of freedom in designing the size of the light-receiving sensor support substrate in the front-back direction of the finder is greater than in the transverse direction of the finder. Therefore, it is possible to increase the size of the substrate, that is, to secure a sufficient size for stably holding the light receiving sensor, and to improve the assembling and assembling property in the finder structure.

The structures described in the above items (2) to (6) facilitate the alignment and positioning of the optical members constituting the photometric system, and are advantageous in that they are easy to design, assemble, and have high accuracy.

(Embodiment) FIGS. 1A and 1B show an embodiment. The same reference numerals are given to the same constituent members and portions as those in the examples of FIGS. 4 (a) and 4 (b), and the description will not be repeated.

In this embodiment, the photometric imaging lens of the photometric system and the reflecting surface member are integrally formed (molded) having a refracting surface portion 11a acting as an imaging lens and a reflecting surface portion 11b acting as a reflecting surface member. Optical element 11A. The light transmitted through the half mirror 5 and entering the optical element 11A from the refraction surface portion 11a is reflected downward by the reflection surface portion 11b of the optical element 11A. That is, the transmission path of the half mirror transmitted in the front-rear direction of the finder is changed downward by a reflection surface portion 11b in a direction substantially perpendicular to the transmission path of the half mirror. Optical element
In the case of this embodiment, the colored glass 12 is previously positioned and adhered to the light emitting surface of 11A. Light reflected downward by the reflection surface portion 11b passes through the color glass 12 from the light emission surface of the optical element 11A, and faces the color glass 12
Light enters 13

The half mirror 5 is held by a finder structure 20. The optical element 11A to which the colored glass 12 is adhered is also held by the finder structure.

The substrate 14 supporting the light-receiving sensor 13 is positioned in a horizontal posture substantially parallel to the front and rear direction of the finder. The positioning dowel 20a protruding from a part of the finder structure 20 with respect to the finder structure 20 and the substrate 14 side. The dowel engaging hole 14a is fitted to and engaged with the dowel engaging hole 14a to be mounted and supported.

Thus, the size of the light receiving sensor holding substrate 14 is
Compared to the viewfinder cross-sectional direction in FIGS.
Since the finder has a greater degree of design freedom in the front-rear direction, the substrate 14 can be made large enough to hold the light receiving sensor 13, and the finder structure
Easy to assemble and assemble for 20.

When the colored glass 12 interposed between the optical element 11A and the light receiving sensor 13 is bonded and fixed to the optical element 11A, mutual positioning (alignment) means, for example, positioning, is provided on one or both of the optical member 11A and the colored glass 12. Protrusions, holes and fittings may be provided. FIG. 2 shows an example in which a concave portion 11c into which the colored glass 12 is fitted is provided on the light emitting surface of the optical element 11A, and the two members 11A and 12 are positioned relative to each other. Most colored glass
The 12 may be independently attached to and supported by the finder structure 20.

Further, one or both of the optical element 11A or the colored glass 12 integrally bonded to the optical element 11A and the light receiving sensor 13
Alternatively, a mutual positioning means, for example, a positioning protrusion, a hole, and a fitting portion may be provided on the substrate 14 holding the sensor. FIG. 3 shows that the colored glass 12 is positioned on the optical element 11A through the fitting concave hole 11c and adhered thereto.
A dowel 11d for positioning is provided in a part of 1A, and this dowel 1
1d and the dowel fitting hole 14b provided on the light receiving sensor substrate 14 side are fitted and adhered or welded to form an optical element.
An example in which 11A and the light receiving sensor 13 are aligned is shown.

(Effects of the Invention) As described above, according to the present invention, it is possible to secure a sufficient size for the light-receiving sensor holding substrate of the photometric system to stably hold the light-receiving sensor, and to incorporate the light-receiving sensor into the finder structure.・ Assemblability improves. In addition, the positioning and positioning of the optical members constituting the photometric system are facilitated, the design is easy, the assembling is easy, and the accuracy can be improved, and the intended purpose is well achieved.

[Brief description of the drawings]

FIG. 1A is a schematic view of an optical system according to an embodiment, and FIG.
FIG. 2 is an enlarged vertical sectional view of the photometric system portion, FIGS. 2 and 3 are schematic diagrams of examples of positioning means for optical members constituting the photometric system, and FIG. 4 (a) is a schematic diagram of a conventional optical system. FIG. 2B is an enlarged vertical sectional view of the photometric system. Reference numerals 1 to 10 denote a finder optical system, 11 to 13 are photometric optical systems, 5 is a half mirror, 11A is a molded optical element, 13 is a light receiving (photometric) sensor, and 14 is a supporting substrate thereof.

Claims (6)

(57) [Claims] 1. A finder image formed on a first object plane by an objective lens provided independently of a photographing system is re-imaged on a second object plane by a secondary imaging lens via a field lens.
A half mirror for dividing an optical path is provided between the field lens and the secondary imaging lens of an external finder system for observing the second object image with an eyepiece, and a light beam reflected by the half mirror A finder optical system that guides the light flux passing through the half mirror to a photometric system including a condenser lens and a light receiving sensor, and a part of the photometric system. A reflection member for reflecting the transmitted light beam from the half mirror in a direction substantially perpendicular to the finder optical axis is provided, and the light receiving sensor is supported on a substrate mounted and fixed to the finder structure substantially in parallel with the finder optical axis. A finder optical system having a photometric system, wherein a light beam is incident on the light receiving sensor via a member. 2. The photometric device according to claim 1, wherein said condensing lens and said reflecting member are constituted by an integrally formed optical element having a refracting surface portion acting as a condensing lens and a reflecting surface portion. Finder optical system with a system. 3. A finder optical system having a photometric system according to claim 2, wherein a color glass is interposed between said optical element and said light receiving sensor by being adhered and fixed to said optical element. 4. A finder optical system having a photometric system according to claim 3, wherein one or both of said optical element and colored glass which are bonded and fixed to each other are provided with mutual positioning means. 5. The photometric system according to claim 2, further comprising a dowel and a dowel engaging portion for positioning the optical element and the light receiving sensor substrate relative to each other. Viewfinder optical system. 6. A finder optical system having a photometric system according to claim 5, wherein a fitting portion for mutual positioning is provided between said optical element and said light receiving sensor.