JPS59189329A - Focal plate and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a focal plate which is brighter than a conventional one and provides similar out-of-focus image by slanting axial lines of microprisms so that peaks are inward more and more from the center toward the circumference of the focal plate, and providing such directivity that transmitted light enters an iris efficiently. CONSTITUTION:Light incident to the microprism 18 which has an acute angle is refracted acutely, so the quantity of light incident to the iris 17 is small and a finder is dark. For this purpose, a smooth shape like a prism 19 is employed effectively to eliminate the above-mentioned problem. Then, the directivity is so determined that only light scattered by a mat surface 21 enters the iris 22. Namely, a microprism 11 is used as a center part, microprisms 12 are used as longitudinal and lateral parts, and microprisms 12 are used as corner parts as shown in a figure to guide a directional line 23 to the iris 22. Thus, the shape of prisms of the mat surface are determined so that the center of scattering coincides with the iris 17, obtaining the mat which is brighter than before and provides the same out-of-focus images as before.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a focusing plate for use in a single-lens reflex camera.

A focusing plate used in a single-lens reflex camera focuses the entire image on the film surface. For this imaging,
A frosted glass-like matte surface is formed on the focus plate. The most important thing for a matte surface is that the viewfinder image is bright (and easy to focus on).If you improve the diffusivity of the matte surface, the blur will be thicker and it will be easier to focus, but The viewfinder becomes noticeably darker.In order to make the viewfinder brighter, it is better to reduce the diffusivity and make it almost clear, but this will reduce the ability to detect blur.

The conventional matte and machine-polished surface of the mold is roughened by sanding and transferred to an acrylic surface.

It is composed of a collection of tiny prisms with sharp edges of irregular shapes and sizes.

When light enters this prism, it is originally bent at a sharp angle, so much of the light does not reach the eye, darkening the viewfinder.

In order to improve this point, a focusing plate with a configuration based on Japanese Patent Application Laid-Open No. 52-27634 was developed as shown in FIG. It is a cone with a diameter of about 20μ, a base surface of about 15 degrees, a rounded tip, and fine irregularities on the surface.

The height of the cone from the bottom is approximately 2.7μ. The details of this part are shown in Figures 2a and b, and the minute cone 2 is located at the center point 3.
The cones are regularly arranged with the microscopic surfaces 4 sandwiched between each cone 2 with the apex being the circumference 6 and the bottom being the circumference 6.

FIG. 3 shows how this honeycomb mat is used. The Fresnel lens 7 on the back side of the mat with cones 2 generates power directed toward the pupil angle α, but since the honeycomb mat scatters photons in a flat state, the scattered light enters the heel and tilt angle α, and the brain This results in an element 8 passing outside the capsule λ angle. The light passing through the flat part 4 between the cones passes without becoming scattered light.

Mat and cone body 2 described in JP-A No. 57-13436
Although the surface of the substrate 10, that is, the microscopic surface 4 is a flat (one curved surface), the original diffusion does not occur at the inflection point.
There is no big difference in that the amount of blur is insufficient.

Focusing plates that use a laser to form and transfer random smooth irregularities onto a mold, creating an effect similar to microtourism, are also in use.

It is not locally available and is extremely expensive.

In a reticle using microprisms, the light that passes through the microprisms, especially at the periphery, is not concentrated on the pupil, resulting in a large amount of original loss, resulting in a total loss of brightness of the reticle.

The object of the invention is to provide a complete reticle in the form of a microprism, which is brighter than known reticle lenses and has a similar blur quality.

The outline of the reticle according to the present invention is that the axis of the microprism is y-perpendicular to the reticle at the center of the reticle, and the apex is tilted outward from the center of the reticle. Make sure that the first passing source falls within the pupil angle for maximum efficiency.

According to the present invention, the part txP where the scattered light after passing through the microprism enters the pupil angle! ￥: The number of microprisms of knowledge increases significantly and becomes a bright dot plate.

Embodiments and drawings illustrating the present invention will be described.

4th-,-1. , OX diagram shows an embodiment of the present invention, and the fourth
FIG. 9 shows various microprisms arranged in the reticle according to the present invention, and FIG. 10 shows the arrangement of the microprisms.

The fourth figure shows the angle θ1°192 with the base of the microprism.
, 0s, and e are all equal, that is, a microprism with the same shape as a normal microprism. The fifth focal diagram shows the angle θ1. A microprism with the same value as ``Tohe'' but different from ``Tohe'', Figure 6''@ shows a prism with different θ and θ, and θ and ``Tohe'' are different. 4〉 is also a microprism with a 1°C diagram, whose ridge lines and apex are removed by chemical processing such as etching or plating, etc., to form a minute convex lens shape, and furthermore, extremely fine unevenness is added to the entire surface.By this, It is originally directed in a certain direction and spreads.

FIG. 10 schematically shows the state in which the microprisms shown in FIGS. 7 to 9\°C are arranged on the matte surface of the focus plate. 1st o
As shown in the figure, the 9th microprism 13 shown in the figure is arranged at the corner of the mat, and the 8'
``The micro prism 12 shown in Fig. 1 is arranged.Although not shown, the micro prism 11 shown in Fig. 7 is arranged in the center. In other words, the present invention provides such directivity that the most of the particles that pass through the mat section are concentrated on the hoof.

The optical effect will be explained.

FIG. 11 shows a case where the surface 16 of the Fresnel lens 150 is flat, and the light passing through the lens 15 is directed toward the pupil 17. However, when one surface 16 is a matte surface, the light becomes scattered light. In this case, the light scattered within the range of the pupil angle α enters the pupil 17, but the light scattered in other directions becomes inactive.

Figures 1 and 2 show the difference in the properties of the matte surface, showing microprisms 18 with sharp corners and microprisms 19 with a smooth shape. Since the light beam incident on the microprism 18 is bent at an acute angle, the light weight incident on the lens 17 is small and the finder becomes dark. In order to eliminate this problem, it is advantageous to have a smooth shape like the prism 19. In this case, the angle θ with the base is 8° to 1
Set to 0°. At this time, when the lens aperture F is small, it is extremely bright, but when F is large and n is large, the amount of light is small. Kon
In order to avoid this, the surface of the microprism is usually roughened, but there is a significant amount of scattered light that does not enter the vinegar 17, that is, there is a significant amount of elements that cannot be effectively utilized.

1 and 3 show the characteristics of the mat according to the present invention, and clearly show that the mat has directionality so that the light scattered on the mat surface 21 enters the pupil 22 as much as possible.

In order to make the directivity line 23 enter the point 22, the center part should be the microprism 11 shown in Figure 7, the vertical and horizontal directions should be the microprisms 12 shown in Figure 88, and the corners should be the microprisms 12 shown in Figure 9. The microprism 13 shown in FIG. 10 has the configuration shown in FIG.

In this way, by adjusting the shape of the prism on the matte surface so that the center of scattering is always in the direction of the pupil 17, a matte that is significantly brighter than the conventional matte and has the same blur as the conventional matte can be obtained. .

The method for manufacturing the above-mentioned mat of the present invention will be briefly explained.

As shown in Fig. 14, using a cutting tool 25 with a tip angle θ,
In the case of the center portion shown in FIG. 141, the inclination angle ΔB is set to 0°.

The inclination angle ΔB is sequentially changed in the outer circumferential direction, and in Fig. 14a, -
ΔB, and in FIG.
The pitch P of the upper microprisms was preferably about 20μ.

Determination of pitch and change of inclination angle can be easily performed by computer control. The apex and ridgeline of the female microprism on the mold machined in this way are etched or plated to blur.

Figures 13 and 13 show the completed mold with the required rough surface.
Obtain the focusing plate shown in the figure.

FIG. 15 shows a comparison of brightness between a conventional mat and a mat according to the present invention. MA is a traditional sand-printed mat, Hi B&
Z known microprism mat.

Line C shows the pine needle according to the invention; HD Matsu) G! As mentioned above, it cannot be used because of the blur. The mat of the present invention is superior in brightness to the conventional mat, and is similar to the mat of line B in terms of blur.

The effects of the focusing plate mat according to the present invention are as follows.

Compared to conventional microprism mats and mats with random irregularities, a significantly brighter mat with the same level of blur was obtained.

This process is performed using a matte laser or the like to create random irregularities, and it is impossible to form the same pattern and is very expensive.

Since the present invention is finished by machining and simple etching, it is extremely easy to reproduce and can be manufactured at low cost.

[Brief explanation of drawings]

Figure i1 ft An enlarged view of the microprism of the known reticle,
2(a) is a partial enlarged view of FIG. 1, FIG. 2(a) is a partial sectional view taken along the line A--A in FIG. 2(a), FIG. Figure 5.6 shows the basic configuration diagram of each Tsukuda microprism used in the focusing plate of the present invention, and Figure 4a,
b and c are the plan view, front view, and side view of the microprism;
Figures 5a, b, and c are the top view, front view, and front view of the microprism; Figures 6a, b, and c are the top view, front view, and side view of the microprism; 7.8.9 Figure 4.5.6
The completed diagrams of the corresponding microprisms are shown in the figures, and Figures 7a, b, and c are plan views, front views, and
Figure 8 a, b, and C are the top view, front view, and side view of the microprism. Figure 9 a, b, and c are the top view, front view, and side view of the microprism. Figure 10 is the main view. A diagram showing the arrangement of various microprisms on the invention reticle, FIG.
FIG. 12 is a diagram showing light transmission of a known focusing plate, FIG. 13 is a diagram showing light transmission of a focusing plate of the present invention, and FIG. 14 a, b, and c show processing of a matrix of a microprism of the present invention. Figure, No. 15
The figure is a diagram showing the brightness of the focusing plate of the present invention. 1, 7.14.15 --- i point plate 2.11.12.1; 3.18.19.21 --- Micro prism 17.22... Pupil (11) Figure 1 Figure 2 ( a) (b) Figure 3 Figure 4 ((1) (b) (C) Figure 5 (Q) (b) (C) Figure 6 (a) (b) (c) Yu 11 M No. 10 Figure 141 - Zhu 11 Kyo 6 Figure 12 Figure 14 (Q) (b) (C) Lens F-number procedure?nTj2E book (self-motivated) July 1981 911 1. Indication of the incident 1982 Patent Application No. 64245 2, Name of the invention Focusing plate, manufacturing method 3, Relationship with the case of the person making the amendment Patent applicant address: 2-43-2-4 Hatagaya, Shibuya-ku, Tokyo, Agent 6, Subject of amendment 7. Contents of the amendment (1) The claims are amended as shown in the attached sheet. (2) The description of "J7 directed outward" on page 4, line 17 of the specification is amended to read "directed inward". (3) In the drawings, Figure 10 is amended as shown in the attached amended drawing. 8. List of attached documents (1) 1 attached sheet (2) Supplementary 11 drawings 1 attached sheet 2. Claims ( 1) Focus plate pine for reflex nonomera 1~
A large number of tiny microprisms are arranged on the surface, and the axes of the microprisms are tilted from the center of the reticle to the apex or inward from the center of the reticle in the 9L direction to efficiently direct the passing light into the pupil. A focus plate characterized in that it has a directivity 11' so as to enter the focus plate. (2) the prism blurs the prism apex angle and ridgeline;
2. The focusing plate according to claim 1, wherein the focusing plate has a matte surface. (3) When applying a hide to the mold surface to process the surface and use it as a matrix for a refocusing plate for a nonomera, the bipedal hide axis should be perpendicular to the surface at the center of the mold, and from the center to the periphery. A method for manufacturing a focusing plate for a nonomera, characterized by forming a large number of microprism master molds by sequentially tilting the bite axis inward with respect to the perpendicular line of the mold surface. -1-

Claims (3)

[Claims] (1) The matte surface of the focus plate for reflex cameras is tilted toward the matte surface of the focus plate to provide directivity so that the first passing light efficiently enters the pupil angle. A focus plate featuring: (2) The focusing plate according to claim 1, wherein the prism has a prism apex angle, a ridge Hf, and a blur 1 surface as a matte surface. (3) When the mold surface is machined with a bit-cutting edge to form a matrix for a focusing plate for a camera, the biting @ line is perpendicular to the plane in the center of the mold. A method for manufacturing a focusing plate for a camera, which comprises forming a large number of microprism master molds by sequentially tilting the bite axis outward from the perpendicular line of the mold surface from the center toward the periphery. .