JPH036488B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a focusing screen matrix used in manufacturing a focusing screen to be included in a focusing plate of a single-lens reflex camera, etc. This relates to a manufacturing method.

(Prior Art) Conventionally, as a method for manufacturing a focusing screen for use in a focusing plate of a single-lens reflex camera, a mold having an uneven surface is prepared, and a mold made of, for example, acrylic resin is used. A technique is known in which the above-described uneven shape is transfer-molded onto a plastic optical material.

As a method for producing this mold, for example, sand or the like is rubbed on the surface of a metal plate to form uneven portions. However, as can be understood from FIG. 2, which shows a schematic cross-section of the mold, most of the concavo-convex portions 13 of the mold 11 obtained by this method are formed in a pointed shape. For this reason, in a focusing screen (not shown) manufactured by transferring the uneven portion 13, the incident light is bent at a steep angle, and the brightness of the image obtained through the finder is low and grainy. It had the disadvantage that it was conspicuous.

In order to improve the above-mentioned drawbacks, a focusing screen matrix (hereinafter sometimes simply referred to as a matrix) with optically uneven parts was produced,
Furthermore, a technique for manufacturing a focusing screen by molding an optical material using a mold onto which the irregularities of a mother mold are transferred has been developed and put into practical use by electroforming.

In this manufacturing technology, the shape of the matrix that defines the surface shape of the focusing screen is
It is accurately reflected on the focusing screen as a product through a mold that is transferred by electroforming. Therefore, in the manufacturing technology mentioned above,
The production technology of the matrix becomes important, and related technologies include:
For example, JP-A-57-148728, or JP-A-59
The one disclosed in Japanese Patent No. 208536 is known.

Among these techniques, according to the matrix manufacturing technique proposed in JP-A No. 57-148728, a mask is placed on the surface of a photosensitive material such as a substrate coated with a resist material or a gelatin dry plate. A master mold is produced by projecting the defined regular fine pattern, performing a predetermined development (or bleaching) process, and forming the above-mentioned photosensitive material as an uneven portion.

In the matrix obtained in this way, for example, the distance Δt between a mask defining a fine pattern and a photosensitive material coated with a photosensitive material is changed to a predetermined value and exposure is performed, thereby forming a pattern on the surface of the matrix. It is possible to change the shape of the uneven portion.

Hereinafter, the technology disclosed in the above-mentioned publication will be explained with reference to the drawings.

FIGS. 3A to 3C are explanatory diagrams showing schematic cross sections of the matrix. In these figures, components having the same functions are designated by the same reference numerals.

First, when the mask and the photosensitive material are brought into close contact with each other and exposed with the distance Δt described above being substantially O, as can be understood from FIG. 3A, the substrate 1
5, the shape of the uneven portion 17a formed on the mask accurately transfers the planar shape of a fine pattern of a mask (not shown), and each uneven portion 17a has a flat portion 19, and the ridge line has a right angle. Thus, the matrix 21 is constructed.

Further, when exposure is performed with a distance Δt of about 20 μm, the outline of the image formed on the surface of the photosensitive material through the mask is blurred by the diffracted light. Therefore, as shown in FIG. 3B, a matrix 23 is obtained in which the uneven portion 17b has the above-described flat portion 19 and the ridge line is a slope.

Furthermore, the distance Δt is made larger than the above value,
When the degree of diffraction is increased, the above-mentioned flat portion 19 disappears and the uneven portion 17c forming the matrix 25 becomes a continuous gentle curve, as shown in FIG. 3C.

(Problems to be Solved by the Invention) However, with the above-mentioned conventional technology, the matrix is formed only by optical methods, so it is difficult to obtain the desired unevenness according to the design. There was.

That is, first, as can be understood from FIGS. 3A and 3B, the uneven parts 17a and 17b including the flat part 19
In this case, the straight component of the light that passes through the focusing screen as a product increases, resulting in insufficient blur.

Furthermore, as shown in FIG. 3C, in the uneven portion 17c consisting of a continuous gentle curve,
At the inflection point indicated by the symbol , a phenomenon similar to that of the flat portion 19 described above occurs, and the light diffusion efficiency decreases, resulting in insufficient blur.

An object of the present invention is to provide a method for manufacturing a focusing screen matrix that solves the above-mentioned conventional problems, and to easily and easily manufacture a focusing screen that can achieve good blur. There is.

(Means for Solving the Problems) In order to achieve this object, according to the method for producing a focusing screen matrix of the present invention,
In a method for producing a matrix for a focusing screen, in which a regular fine pattern defined on a mask is projected onto a photosensitive material adhered to a substrate, exposed to light, and then developed to form uneven parts. , After forming an uneven part where the part corresponding to the fine pattern is flat and the ridge line between the flat parts is a slope,
It is characterized in that the uneven portion is heat-treated for a required period of time at a temperature that gives fluidity to the photosensitive material after curing, so as to cause the edges connected to the slopes to flow slightly.

(Function) According to the configuration of the method for producing a focusing screen matrix of the present invention, fluidity is generated in the edges constituting the uneven portion with respect to the uneven portion obtained by an optical method. The heat treatment is carried out for a period of time to cause the part to flow slightly at a certain temperature. Therefore, it is possible to eliminate the above-described flat surface and form an uneven portion without inflection points.

(Example) Hereinafter, with reference to the drawings, an example of the method for producing a focusing screen matrix according to the present invention will be described.

It should be noted that the drawings referred to in the following description are merely shown schematically to the extent that the present invention can be understood.
It should be understood that the invention is not limited only to these illustrated examples.

Further, in the following description, in order to facilitate understanding of the description, conventionally well-known steps will also be described in detail.

FIGS. 1A to 1D are explanatory diagrams schematically showing each manufacturing process for obtaining a matrix. In the drawings, components having the same functions as those already described are designated by the same reference numerals. In addition, in these figures, in illustrating the various components used in the examples, except for FIG. It is shown in the same way as FIGS. 3A to 3C.

First, the mask used in this example will be briefly explained with reference to FIG. 1A.

The mask 29 used in this example is made of a glass plate, and has a dot-like fine pattern 31 made of chromium (Cr) with a pitch of about 15 to 25 (μm).
and printed with a diameter of about 10 to 16 (μm).

Next, the exposure process will be explained with reference to FIG. 1B.

First, prior to exposure, a substrate 1 made of glass is
5, a positive resist material as a photosensitive material 33 is uniformly applied to a predetermined thickness within a film thickness range of approximately 2 to 3 (μm), thereby producing a photosensitive material 35.

Next, similarly to the technique disclosed in the above-mentioned publication, the surface of the mask 29 on the fine pattern 31 side and the surface of the photosensitive material 35 on the photosensitive material 33 side are made to face each other for alignment. At this time, the distance Δt between the mask 29 and the photosensitive material 35 was set to about 20 (μm).

Thereafter, light indicated by a series of arrows a in the figure is irradiated toward the photosensitive material 35 from the side of the mask 29, and a fine pattern 31 is projected onto the surface of the photosensitive material 33, thereby performing exposure. .

After passing through the above-described steps, a phenomenon treatment is performed to form the exposed photosensitive material 33 as an uneven portion having a predetermined shape.

The shape of the uneven portion obtained in the above-mentioned exposure process is
It has a shape as already described with reference to FIGS. 3A-3C. Among these three shaped uneven parts,
By using the method of the present invention, various shapes can be considered as the shape of the uneven portion after exposure in order to eliminate the above-described flat surface and form an uneven portion without inflection points.

Hereinafter, with reference to FIG. 1C, a preferred shape of the uneven portion after exposure obtained after the above-described exposure process will be described in detail.

FIG. 1C is an explanatory diagram showing a case where the uneven portion 17b shown in FIG. 3B, which has already been explained, is formed.

As can be understood from this figure and the above explanation, the uneven portion 1 after exposure is preferably applied to the present invention.
7b is formed under the conditions that at least the flat portion 19 and the edge portion 27 defining the portion 19 are formed.
The conditions mentioned here include not only the value of the distance Δt described above, but also the exposure amount, the film thickness of the photosensitive material 33, the development conditions of the material 33, the γ value of the material 33, or other conditions, and may be arbitrarily selected. Select and set.

Next, by heat-treating the uneven portion 17b described above, the uneven portion 39 has a continuous arc-shaped cross-sectional shape as shown in FIG. Ta.

A detailed explanation of the conditions for this heat treatment is as follows:
The heating temperature was set at a value close to the flow temperature of the resist material used for the photosensitive material 33 after curing, and in this example, the heating temperature was within the range of approximately 150 to 200°C. Further, the time conditions are preferably within a time range of approximately 5 to 10 minutes when the temperature range is as described above.

By carrying out the heat treatment under the above-mentioned temperature and time conditions, the surface layer of the uneven portion 17b shown in FIG. 1C, except for the deeper layer, is softened and has slight fluidity. Then, a slight volume movement (downward movement due to gravity) occurs in the surface layer, especially the edges 37 of the uneven portions 17b, and as a result, the shapes of the flat portions and the edges are averaged, and each of the uneven portions 39 becomes approximately uniform. It was possible to form the matrix 41 in the form of an arcuate convex portion having a cross-sectional shape.

After obtaining a mold using such a matrix 41,
When molding optical materials in the same way as before,
We were able to produce a bright focusing screen with excellent diffusivity and no graininess.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

For example, in the above-described embodiments, a positive resist material was used as the photosensitive material, but the present invention is not limited to this, and a negative resist material may also be used. In addition, at least as illustrated in FIG. The material is not limited to the above materials as long as it can be formed into a curved surface shape without curved points.

It is clear that these materials, shapes, arrangement relationships, numerical conditions, and other conditions can be modified and changed as desired according to the design without departing from the scope of the present invention.

(Effects of the Invention) As is clear from the above description, according to the method for manufacturing a focusing screen matrix of the present invention, the uneven portions obtained by an optical method are heat-treated, and the above-mentioned It becomes possible to eliminate the flat surface and form uneven portions without inflection points.

Therefore, by using the focusing screen matrix obtained by the manufacturing method of the present invention, it is possible to efficiently diffuse light without impairing brightness, eliminating graininess, and producing good bokeh. It becomes possible to simply and easily manufacture an excellent focusing screen.

[Brief explanation of the drawing]

FIGS. 1A to 1D are diagrams for explaining an embodiment of the present invention, and FIGS. 2 and 3A to 3C are diagrams for explaining the prior art. 11... Molding mold, 13, 17a, 17b, 17
c, 39... Uneven part, 15... Substrate, 19... Flat part, 21, 23, 25, 41... Mother mold, 27...
...Inflection point, 29...Mask, 31...Fine pattern, 33...Photosensitive material, 35...Photosensitive material, 37...
...Edge, a...Light used during exposure.

Claims (1)

[Scope of Claims] 1. A focusing screen in which a regular fine pattern defined on a mask is projected and exposed onto a photosensitive material adhered to a substrate, and then a development process is performed to form uneven portions. In the method for producing a mother mold, after forming an uneven portion in which the portion corresponding to the fine pattern is flat and the ridge line between the flat portions is an inclined surface, the uneven portion imparts fluidity to the photosensitive material after curing. A method for producing a matrix for a focusing screen, comprising heating at a temperature for a required period of time so as to cause the edges connected to the slopes to slightly flow.