JPS6271884A - Cover glass for timepiece with diffraction grating - Google Patents

Abstract

PURPOSE:To obtain a diffraction grating which is corrected freely without any deterioration in the strength of a glass cover by etching a specific metallic thin film formed on the glass surface by a PVD method and forming the diffraction grating which has specific transmissivity and size. CONSTITUTION:The metallic thin film 2a of Cr2O3, Cr, Au, Ni, etc., is formed on the cover glass 1 for a timepiece by the PVD method and etched to form such a diffraction grating 2 that the light transmissivity of the pattern is 20-80% and the width and pitch of the grating are >=1mum and <=7mum. Then, the diffraction grating which has no deterioration in the strength of the glass cover and is corrected freely is obtained by the constitution in which no diffraction grating is formed by making the glass uneven.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a watch cover with a diffraction grating.

[Conventional technology]

As for the conventional technology, the patent application 4F-! ;0640, after applying a photosensitive resist paint to the back surface of a watch cover glass, placing a screen with a diffraction grating carved in the no'=turns on the photosensitive resist surface;
After exposure and development to remove the resist in non-exposed areas, etching is performed with chemicals such as hydrofluoric acid to form a pattern of diffraction gratings directly on the back surface of the watch cover glass.

[Problem that the invention seeks to solve]

This conventional watch cover glass with a pattern formed by a diffraction grating has many minute recesses on the back side, which causes its strength to deteriorate.Furthermore, watch cover glasses are generally strengthened to increase their strength. is applied, and a stress layer is formed on the entire surface layer, so if minute recesses are made in a part of the surface, the balance of the stress layer will be shifted (shifting, and even a weak force from a certain direction can easily In addition, there are many minute recesses on the back of the watch cover glass (because they are created by chemical etching, if the pattern created by the diffraction grating becomes unclear due to poor etching, it is almost impossible to correct it, and the watch cover glass became a defective product.

The present invention solves one of the drawbacks of the above-mentioned conventional watch cover glass patterned with a diffraction grating, and allows the intensity of the iridescent interference color obtained from the diffraction grating to be clearly changed, and can be formed into any shape. The aim is to create a watch cover glass with a diffraction grating that provides a new patterned design, eliminates the worry of strength deterioration of the watch cover glass due to the diffraction grating, and can be modified as necessary. do.

[Means for solving problems]

In order to achieve the above object, the present invention has a structure in which a metal thin film of Cr2O3, Cr, Au, Ni, etc. is formed on the surface of a watch cover glass by a PVD method, and a part of the metal thin film is removed by photoetching. The pattern formed by the diffraction grating is characterized in that the transmittance is 20% or more and 80% or less, and the grating width and pitch of the diffraction grating are each 1μ or more and 7μ or less.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the drawings.

1 and 2 show a first embodiment of the present invention, and FIG. 1 is an enlarged sectional view of a diffraction grating provided on a watch cover glass.
FIG. 2 is a plan view of a watch cover glass on which a pattern of diffraction gratings is formed.

On the back surface of the watch cover glass 1 (the surface that faces the dial when the completed watch is attached to the case), a thin metal film made of C203 is formed to a thickness of 52oX using the PVD vacuum deposition technique.Next After forming a photoresist film on the metal thin film using a spinner, using a mask with a pattern formed by a diffraction grating, exposure and development are performed to remove the photoresist in the unexposed areas.Next, unnecessary photoresist is removed by chemical etching. The metal thin film made of Cr2O3 in the Cr2O3 portion is removed, and a pattern 6 is formed on the back surface of the watch cover glass 1 by a diffraction grating 2 consisting of a grating 2a of the metal thin film made of Cr2O3 and fine slits 2b. 2a is made of 2μ width and 2μ pinch, and the diffraction grating 2
The transmittance is 50%.

The pattern 6 formed by one diffraction grating 2 on the back surface of the watch cover glass 1 in this way is such that the incident light that enters the diffraction grating 2 due to external light is diffracted by the fine sulphur 2b, and the reflected light is Due to interference, it shows a beautiful sparkle as a red color. Also, unlike the conventional technology in which a watch cover glass is provided with many minute recesses, the strength of the watch cover glass 1 is almost the same as before the pattern 6 is formed by the diffraction grating 2, and there is a problem of strength deterioration as with conventional products. There isn't. Furthermore, even if the pattern 3 formed by the diffraction grating 2 has poor appearance quality, the metal thin film of Cr2O3 can be peeled off without damaging the watch cover glass 1 using a chemical method, and the pattern 6 formed by the diffraction grating 2 can be removed again. can be formed.

In the above example, the metal thin film was formed using Cr and O5, and the metal thin film was formed using a vacuum evaporation method, but it is also possible to use Cr, Au, or Ni as the type of metal thin film.
PVD sputtering I as a metal thin film formation method?
etc. is also fine. It is also possible to form a pattern of diffraction gratings on the surface of a watch cover glass. In addition, it is practical and design-friendly to vary the thickness of the metal thin film formed on the back surface of the watch cover glass so that the transmittance of the diffraction grating ranges from 20% to 80%, and is lower than 20% ( If it becomes higher than 80%, the beautiful rainbow-colored sparkle will decrease.Also, regarding the rainbow-colored interference color depending on the grating width and pitch range and transmittance of the diffraction grating, A combination of grating width from 1μ to 7μ and pitch from 1μ to 7μ has a transmittance of 2.
The case of 0% to 80% was good as a deep red color.

If the grid width and pitch are thicker than 7μ, the number of rainbow colors will decrease, and even if either one is larger than 7μ, the number of rainbow colors will decrease.Also, if the grid width and pitch are 1μ
The smaller the size, the better the rainbow colors will appear, but due to processing problems such as photo-etching, mass production is extremely difficult.Therefore, the grating width, pitch,
The transmittance is arbitrarily selected from the above range and used in combination.

An example of the combination of grating width and pitch of the diffraction grating is shown in Table 1 below.
Shown below. Table 1 shows that the grating width of the diffraction grating is 2μ and the pitch is 2μ.
In this case, the material of the metal coating is Cr, 0. , or C
It shows the transmittance and the thickness of the metal thin film when r.

Next, FIG. 3 shows a second embodiment of the present invention, and is an enlarged sectional view of a diffraction grating and a printed backing section provided on a watch cover glass.

An organic ink is used for the pattern portion of the diffraction grating 2 made of C r 20 s, which is formed on the back surface of the watch cover glass 1 in the same manner as in the first embodiment, and a backing printed portion 4 is formed by printing.

The pattern of the diffraction grating 2 created on the back side of the watch cover glass 1 in this way is a combination of the iridescent color of the diffraction grating 2 and the color of the organic ink used for the back printing part 4. Harmony allows for a new sense of design expression.

Other than the above, the explanation is omitted since it is the same as the first embodiment.

Next, FIG. 4 shows a third embodiment of the present invention, and is an enlarged sectional view of a diffraction grating and a backing metal thin film provided on a watch cover glass.

A metal such as Ag or Au is used for the pattern portion of the diffraction grating 2 made of Cr2O3, which is formed on the back surface of the watch cover glass 1 in the same manner as in the first embodiment, and a backing metal is formed using the vacuum evaporation technique of the PVD method. A thin film portion 5 is formed.

In the pattern part of the diffraction grating 2 made on the back surface of the watch cover glass 1 as shown in 2, the red color showing the sparkling and beautiful shine of the diffraction grating 2 becomes even more brilliant due to the reflection from the backing metal thin film part 50, making it even more jewel-like. As well as improving the design, design variations can be expanded.

Although the backing metal thin film portion was formed using the vacuum evaporation technique of the PVD method, sputtering or IP of the PVD method may also be used. In addition, the metal used to form the backing metal thin film part is
If a metal with a high reflectance is used, the iridescent color of the patterned portion of the diffraction grating will shine more beautifully.

Note that other than the above, the explanation is omitted since it is the same as in the i1 embodiment.

〔Effect of the invention〕

As is clear from the above explanation, the cover glass for a watch with a diffraction grating of the present invention has a pattern of a diffraction grating formed on a metal thin film by photo-notching technology. 1. There is no strength deterioration, and it does not easily break due to external force.7Also, even if the pattern formed by the diffraction grating has poor appearance quality, the metal thin film can be chemically coated without damaging the watch cover glass. Since it can be peeled off, corrections can be made as many times as you like.Also, the transmittance of the diffraction grating pattern is between 20% and 80%, so the time display will not be visible.
Buzanon shows a beautiful shine with moderate iridescent sparkle, improves the jewelry quality of the watch, and gives a new sensation. can be provided.

[Brief explanation of drawings]

Figures 1 and 2: A first embodiment of the present invention is shown, and Figure 1 is an enlarged sectional view of a diffraction grating provided on a watch cover glass.
Fig. 2 is a plan view of a watch cover glass with turns formed by a diffraction grating, Fig. 3 is an enlarged cross-sectional view of the diffraction grating and backing printed portion provided on the watch cover glass, showing the second embodiment; FIG. 4 shows a third embodiment and is an enlarged sectional view of a diffraction grating and a backing metal thin film portion provided on a watch cover glass. 1...Cover glass for watches, 2...Diffraction grating, 2a...Grating, 2b...Fine slit, 6... ...Pattern, 4...Backing printed part, 5...Backing metal thin film part. Patent applicant Citizen Watch Co., Ltd. Kawaguchiko Seimitsu Co., Ltd. Agent Patent attorney Toshi Kanayama Hikohisa τ'5 ゛ ・

Claims (1)

[Claims] A diffraction grating pattern formed by forming a thin metal film of Cr_2O_3, Cr, Au, Ni, etc. on the surface of a watch cover glass by the PVD method and removing a part of the metal thin film by photoetching has a transmittance of 20%. 80% or less, and each of the grating width and pitch of the diffraction grating is 1
A cover glass for a watch with a diffraction grating, characterized in that the particle diameter is greater than or equal to μ and less than or equal to 7 μ.