JP2009186234A - Light-transmitting member and timepiece provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-transmitting member provided with both high resistance to flaws and satisfactory visibility and provide a timepiece provided with the light-transmitting member. <P>SOLUTION: The light-transmitting member 1 has a substrate 10 having a light-transmitting property; a first functional layer 11 formed on the substrate 10; and a second functional layer 12 formed on the first functional layer 11. The refractive index of the second functional layer 12 is smaller than that of the first functional layer 11. Either the first functional layer 11 or the second functional layer 12 is a DLC (Diamond-Like Carbon) layer 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a translucent member such as a cover glass, and a timepiece including the translucent member.

  Conventionally, sapphire glass, quartz glass, soda glass, or the like is used as a cover glass for a watch. However, when these glasses are used alone, the visibility such as time display is poor due to the high reflectance. This is particularly noticeable when sapphire glass having a high refractive index is used. Therefore, a method is known in which an antireflection layer is provided on the surface of glass to improve visibility by suppressing the reflectance (see, for example, Patent Document 1).

On the other hand, since the material of the antireflection layer is often low in hardness, the antireflection layer is easily scratched. On the contrary, there is a possibility that the visibility is deteriorated and the design property is also lowered.
On the other hand, Patent Document 2 discloses a watch cover glass in which a DLC (diamond-like carbon) layer having a high hardness is provided on an antireflection layer to improve friction resistance.

Japanese Utility Model Publication No. 48-77456 JP 2004-93437 A

However, the DLC layer has a high refractive index, and when the DLC layer is formed on the antireflective layer having a low refractive index, there is a problem that the antireflection effect is impaired.
Then, an object of this invention is to provide the translucent member provided with both high scratch resistance and favorable visibility, and a timepiece provided with this translucent member.

  The translucent member of the present invention includes a base material having translucency, a first functional layer formed on the base material, a second functional layer formed on the first functional layer, The refractive index of the second functional layer is smaller than the refractive index of the first functional layer, and one of the first functional layer and the second functional layer is a DLC (diamond-like carbon) layer. It is characterized by that.

According to the present invention, since the DLC layer having high hardness is provided as the first functional layer or the second functional layer, the scratch resistance of the surface of the translucent member can be improved.
In addition, since the refractive index of the second functional layer is smaller than the refractive index of the first functional layer, the difference in refractive index between the surface of the translucent member and air is smaller than when the first functional layer is in contact with air. Get smaller. Thereby, the light transmittance can be increased and the reflectance can be reduced, and the visibility when the other side is viewed through the translucent member can be improved.
That is, according to this invention, the translucent member provided with both high scratch resistance and favorable visibility is realizable.

In addition, the refractive index of a DLC layer can be adjusted with the manufacturing method etc. of DLC among a 1st functional layer and a 2nd functional layer. For example, by implanting a light element such as a hydrogen atom (H) or a fluorine atom (F) into the DLC layer, the refractive index can be lowered without significantly impairing the hardness of the DLC layer. Further, the refractive index of the other functional layer can be adjusted by the material forming the same, the manufacturing method, and the like.
Moreover, although the material of a base material is not specifically limited, For example, sapphire glass, quartz glass, soda glass, etc. are mentioned.

In the translucent member of the present invention, the difference between the refractive index of the first functional layer and the refractive index of the second functional layer is 0.1 or more, and the refractive index of the second functional layer is 1. It is preferable that it is 7 or less.
According to this invention, the refractive index of the surface of the translucent member can be sufficiently reduced, and a good antireflection effect can be obtained.
Here, if the difference between the refractive index of the first functional layer and the refractive index of the second functional layer is less than 0.1, the antireflection effect due to the addition of the second functional layer is reduced, which is not preferable. Note that the difference between the refractive index of the first functional layer and the refractive index of the second functional layer is more preferably 0.2 or more, and further preferably 0.3 or more.
On the other hand, if the refractive index of the second functional layer exceeds 1.7, the difference in refractive index between the surface of the translucent member and air increases, and a sufficient antireflection effect cannot be obtained. The refractive index of the second functional layer is more preferably 1.6 or less, and further preferably 1.5 or less.

In the translucent member of the present invention, it is preferable that at least one of hydrogen and fluorine is added to the DLC layer.
In the present invention, since at least one of hydrogen and fluorine is contained in the DLC layer, coloring of the DLC layer can be prevented.
In addition, a DLC layer having a low refractive index can be obtained due to the presence of hydrogen or fluorine.

In the translucent member of the present invention, the total content of hydrogen and fluorine in the DLC layer is preferably 20% or more and 50% or less in terms of atomic ratio.
In the present invention, since a predetermined amount of at least one of hydrogen and fluorine is added to the DLC layer, coloring of the DLC layer can be appropriately prevented.
Here, when the total content of hydrogen and fluorine in the DLC layer is less than 20% or more than 50% in terms of atomic ratio, the DLC layer may be colored, which is not preferable. On the other hand, if it exceeds 50%, the hardness of the DLC layer may decrease, which is not preferable. The total content of hydrogen and fluorine in the DLC layer is more preferably 25% or more and 45% or less, and further preferably 30% or more and 40% or less in terms of atomic ratio.

In the translucent member of the present invention, the first functional layer is the DLC layer, and the second functional layer is SiO ₂ , MgF ₂ , LiF, Na ₃ AlF ₆ , NaF, CaF ₂ , LaF ₃ , It is preferably formed of at least one of NdF ₃ , Al ₂ O ₃ , CeF ₃ and SiO.
According to the present invention, the second functional layer is formed on the DLC layer having a high refractive index using the material having a refractive index lower than that of the DLC. Thereby, compared with the case where a DLC layer is exposed on the surface, the refractive index of the surface of a translucent member can be reduced, and a favorable antireflection effect can be acquired.
In addition, since the DLC layer having a smooth and high hardness exists under the second functional layer, the second functional layer also becomes smooth and less likely to be scratched, so that the scratch resistance of the surface of the translucent member is improved. Can be improved.
The second functional layer is more preferably formed of SiO ₂ , MgF ₂ or Al ₂ O ₃ from the viewpoint of the refractive index and hardness.

In the translucent member of the present invention, the first functional layer includes Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , MgO, Gd ₂ O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , ZnO, and ZrO _2. , In ₂ O ₃ , Nd ₂ O ₃ , ThO ₂ , SnO ₂ , Sb ₂ O ₃ , CeO ₂ , Bi ₂ O ₃ and HfO ₂ , and the second functional layer is the DLC layer It is preferable that
According to the present invention, the second functional layer formed of DLC having a lower refractive index is provided on the first functional layer formed of a material having a high refractive index. Thereby, compared with the case where a 1st functional layer is exposed on the surface, the refractive index of the surface of a translucent member can be reduced, and a favorable antireflection effect can be acquired.
Moreover, since the DLC layer with high hardness exists on the surface of the translucent member, the scratch resistance of the surface of the translucent member can be improved.
The first functional layer is more preferably formed of Ta ₂ O ₅ , HfO ₂ , TiO _2, or ZrO ₂ from the viewpoint of the refractive index and hardness.

In the translucent member of the present invention, the DLC layer preferably has a thickness of 5 nm to 150 nm.
According to this invention, it is possible to improve the scratch resistance while preventing the DLC layer from being colored and ensuring the transparency of the translucent member.
Here, if the thickness of the DLC layer is less than 5 nm, the scratch resistance cannot be sufficiently improved, which is not preferable. On the other hand, if the thickness of the DLC layer exceeds 150 nm, the DLC layer may be colored, which is not preferable. Note that the thickness of the DLC layer is more preferably 10 nm or more and 140 nm or less, and further preferably 10 nm or more and 130 nm or less.

In the translucent member of the present invention, it is preferable that the thickness of the first functional layer and the thickness of the second functional layer are both 5 nm or more and 150 nm or less.
According to this invention, coloring of the first functional layer and the second functional layer can be prevented, and the transparency of the translucent member can be maintained.
Here, when the thickness of the first functional layer and the thickness of the second functional layer exceed 150 nm, the first functional layer or the second functional layer may be colored, which is not preferable. Note that the thickness of the first functional layer and the thickness of the second functional layer are more preferably 140 nm or less, and further preferably 130 nm or less.
Further, the thickness of the first functional layer and the thickness of the second functional layer are preferably 5 nm or more. If these thicknesses are less than 5 nm, the optical properties and surface hardness may not be sufficiently satisfied.

The timepiece of the present invention is a timepiece provided with the above-described translucent member, wherein the translucent member is provided in a case that accommodates the timepiece body.
According to this invention, the above-mentioned translucent member is provided in a case as a cover glass, for example. At this time, the visibility of information is improved by the antireflection function of the translucent member. And this visibility is maintained over a long period of time by the flaw resistance of a translucent member.

  According to the present invention as described above, it is possible to provide a translucent member having both high scratch resistance and good visibility, and a timepiece having the same.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
[Configuration of translucent member]
In FIG. 1, the schematic layer structure of the translucent member which concerns on 1st Embodiment of this invention is shown.
As shown in FIG. 1, the translucent member 1 of the present embodiment is formed on the base material 10, the first functional layer 11 formed on the base material 10, and the first functional layer 11. A second functional layer 12.

  The base material 10 can be formed of a light-transmitting material such as sapphire glass, quartz glass, or soda glass. The base material 10 of this embodiment is sapphire glass.

The first functional layer 11 is a DLC layer 13 to which hydrogen is added.
Such a DLC layer 13 can be formed by, for example, a plasma CVD method, a sputtering method, an ionized vapor deposition method, or the like.
In the present embodiment, the DLC layer 13 is formed by a plasma CVD method.
For the formation of the DLC layer 13, an apparatus used for normal plasma CVD can be used. The source gas is a hydrocarbon gas such as methane. By incorporating hydrogen into the source gas, hydrogen can be introduced into the DLC layer 13.

Moreover, it is preferable that hydrogen content with respect to the DLC layer 13 is 20% or more and 50% or less by atomic ratio.
If the hydrogen content is 20% or more and 50% or less by atomic ratio, coloring of the DLC layer 13 can be appropriately prevented without reducing the hardness of the DLC layer 13. The hydrogen content in the DLC layer is more preferably 25% or more and 45% or less, and further preferably 30% or more and 40% or less in terms of atomic ratio.
It is important that the refractive index of the DLC layer 13 is not smaller than the refractive index of the first functional layer 11.

Here, the thickness of the DLC layer 13 is preferably 5 nm or more and 150 nm or less.
If the thickness of DLC layer 13 is 5 nm or more and 150 nm or less, coloring of DLC layer 13 can be prevented and transparency of translucent member 1 can be maintained. The thickness of the DLC layer 13 is more preferably 10 nm or more and 140 nm or less, and further preferably 10 nm or more and 130 nm or less.

The second functional layer 12 is formed of at least one of SiO ₂ , MgF ₂ , LiF, Na ₃ AlF ₆ , NaF, CaF ₂ , LaF ₃ , NdF ₃ , Al ₂ O ₃ , CeF ₃ and SiO. Is preferred.
In particular, the second functional layer 12 is more preferably formed of SiO ₂ , MgF _2, or Al ₂ O ₃ from the viewpoint of refractive index and hardness.
In the present embodiment, the second functional layer 12 is made of Al ₂ O ₃ .

The thickness of the second functional layer 12 is preferably 5 nm or more and 150 nm or less.
If the thickness of the second functional layer 12 is 5 nm or more and 150 nm or less, the inherent hardness of the layer can be obtained, and coloring of the second functional layer is prevented, and the transparency of the translucent member is maintained. be able to.
The thickness of the second functional layer 12 is more preferably 140 nm or less, and further preferably 130 nm or less.
The second functional layer 12 is formed by, for example, a plasma CVD method, a sputtering method, an ionization vapor deposition method, or the like.

The refractive index of the second functional layer 12 is smaller than the refractive index of the first functional layer 11.
In particular, the difference between the refractive index of the first functional layer 11 and the refractive index of the second functional layer 12 is preferably 0.1 or more, and the refractive index of the second functional layer 12 is preferably 1.7 or less. .
If the difference between the refractive index of the first functional layer 11 and the refractive index of the second functional layer 12 is 0.1 or more and the refractive index of the second functional layer 12 is 1.7 or less, sufficient antireflection An effect is obtained.
Note that the difference between the refractive index of the first functional layer 11 and the refractive index of the second functional layer 12 is more preferably 0.2 or more, and further preferably 0.3 or more. Further, the refractive index of the second functional layer 12 is more preferably 1.6 or less, and further preferably 1.5 or less.

[Clock structure]
FIG. 2 shows a cross-sectional view of a timepiece having the translucent member 1 as a cover glass.
As shown in FIG. 2, in the timepiece 100 of the present embodiment, the translucent member 1 is provided as a cover glass 2 on a case 4 that houses a timepiece (movement) 3. The case 4 is provided with a back cover 5.
Here, the body surface portion of the cover glass 2 of the present embodiment includes a front surface portion 2A, a rear surface portion 2B, and a side surface portion 2C. The front surface portion 2 </ b> A corresponds to an outer portion of the cover glass 2. The rear surface portion 2 </ b> B corresponds to an inner portion of the cover glass 2 and faces the dial 6 and the pointer 7.
In the present embodiment, the first functional layer 11 and the second functional layer 12 described above are located on the front surface portion 2 </ b> A of the cover glass 2.

[Effects of First Embodiment]
According to the above embodiment, the following effects can be obtained.
(1) Since the DLC layer 13 having high hardness is provided, the scratch resistance of the surface of the translucent member 1 can be improved.
Moreover, since the refractive index of the 2nd functional layer 12 is smaller than the refractive index of the 1st functional layer 11, compared with the case where the 1st functional layer 11 contacts air, the refraction of the surface of the translucent member 1 and air. The difference in rate is reduced. Thereby, the light transmittance can be increased and the reflectance can be reduced, and the visibility when looking through the translucent member 1 can be improved.
That is, according to this invention, the translucent member 1 provided with both high scratch resistance and favorable visibility is realizable.

(2) The difference between the refractive index of the first functional layer 11 and the refractive index of the second functional layer 12 is set to 0.1 or more, and the refractive index of the second functional layer 12 is set to 1.7 or less. The refractive index of the surface of the member 1 can be sufficiently reduced, and a good antireflection effect can be obtained.
(3) Since hydrogen is added to the DLC layer 13, coloring of the DLC layer 13 can be prevented.
In this embodiment, in particular, since the hydrogen content in the DLC layer 13 is set to 20% or more and 50% or less in atomic ratio, coloring of the DLC layer 13 is appropriately prevented without reducing the hardness of the DLC layer 13. be able to.

(4) Since the second functional layer 12 is formed on the DLC layer 13 having a high refractive index using Al ₂ O ₃ having a refractive index lower than that of the DLC, as compared with the case where the DLC layer 13 is exposed on the surface. And the refractive index of the surface of the translucent member 1 can be reduced, and the favorable antireflection effect can be acquired.
In addition, since the smooth and hard DLC layer 13 is present under the second functional layer 12, the second functional layer 12 is also smoothed and hardly damaged, so that the surface of the translucent member 1 It is possible to improve the scratch resistance.

(5) Since the thickness of the DLC layer 13 is 5 nm or more and 150 nm or less, the DLC layer 13 can be prevented from being colored and the transparency of the translucent member 1 can be ensured, and the scratch resistance can be improved.
(6) Since the thickness of the 2nd functional layer 12 was 150 nm or less, coloring of the 2nd functional layer 12 can be prevented and the transparency of the translucent member 1 can be maintained.
(7) In the timepiece 100, since the translucent member 1 is provided in the case 4 as the cover glass 2, the visibility of information is improved by the antireflection function of the translucent member 1. And since the 1st functional layer 11 and the 2nd functional layer 12 are located in the front-surface part 2A of the cover glass 2, this visibility is maintained over a long period by the flaw resistance of the translucent member 1. FIG.

[Second Embodiment]
The translucent member 1 of the present embodiment differs from the first embodiment described above in the contents of the first functional layer 11 and the second functional layer 12. For this reason, the same code | symbol as 1st Embodiment is used, and description of the overlapping part is abbreviate | omitted suitably.

FIG. 3 shows a schematic layer configuration of the translucent member according to the present embodiment.
As shown in FIG. 3, in the translucent member 1 of the present embodiment, the second functional layer 12 is a DLC layer 13.
The formation method, thickness, hydrogen content, and the like of the second functional layer 12 are the same as those of the first functional layer 11 (DLC layer 13) of the first embodiment. However, the refractive index of the DLC layer 13 (second functional layer 12) must be smaller than the refractive index of the first functional layer 11.
Note that the refractive index of the DLC layer 13 can be lowered by containing hydrogen in the layer.

The first functional layer 11 of the present embodiment includes Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , MgO, Gd ₂ O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , ZnO, ZrO ₂ , In ₂ O _3. , Nd ₂ O ₃ , ThO ₂ , SnO ₂ , Sb ₂ O ₃ , CeO ₂ , Bi ₂ O ₃ and HfO ₂ are preferably used.
In particular, the first functional layer 11 is more preferably formed of Ta ₂ O ₅ , HfO ₂ , TiO _2, or ZrO ₂ from the viewpoint of refractive index and hardness.
In the present embodiment, the first functional layer 11 is made of Ta ₂ O ₅ .
The first functional layer 11 is formed by, for example, a plasma CVD method, a sputtering method, an ionized vapor deposition method, or the like.

The thickness of the first functional layer 11 is preferably 5 nm or more and 150 nm or less.
If the thickness of the first functional layer 11 is 5 nm or more and 150 nm or less, the original hardness of the layer can be obtained, and coloring of the first functional layer 11 is prevented, and the transparency of the translucent member is maintained. can do.
Note that the thickness of the first functional layer 11 is more preferably 140 nm or less, and further preferably 130 nm or less.

[Effects of Second Embodiment]
According to the above embodiment, in addition to the above (1) to (3) and (5) to (7), the following effects can be obtained.
(8) Since the second functional layer 12 formed of DLC having a lower refractive index is provided on the first functional layer 11 formed of Ta ₂ O ₅ having a high refractive index, the first functional layer 11 Compared with the case where is exposed on the surface, the refractive index of the surface of the translucent member 1 can be reduced, and a good antireflection effect can be obtained.
Moreover, since the DLC layer 13 with high hardness exists on the surface of the translucent member 1, the scratch resistance of the surface of the translucent member 1 can be improved.

[Modification of the present invention]
The present invention is not limited to the above-described embodiments, and various improvements and modifications can be made within a range in which the object of the present invention can be achieved.
In each of the embodiments described above, the mode in which hydrogen is added to the DLC layer 13 is exemplified, but the present invention is not limited to this. For example, fluorine may be added to the DLC layer 13 instead of hydrogen, or both hydrogen and fluorine may be added. If the thickness of the DLC layer 13 is 20 nm or less and transparency is ensured, hydrogen or fluorine may not be added.

  In each said embodiment, although the 1st functional layer 11 and the 2nd functional layer 12 were formed only in the front part 2A of the cover glass 2, you may form also in the rear surface part 2B. Here, the antireflection performance of the cover glass 2 can be further enhanced by forming the first functional layer 11 and the second functional layer 12 on both the front surface portion 2A and the rear surface portion 2B.

  In each of the above embodiments, the example in which the present invention is applied to the cover glass 2 as a windshield is shown, but the translucent member 1 of the present invention is not limited to the cover glass 2 as a windshield. In a mechanical timepiece or the like, a translucent member 1 as a cover member is provided at a position where a back cover 5 (see FIG. 2) is provided, and a mechanism inside the timepiece 3 is visually recognized through the translucent member 1. It may be considered as a see-through back specification. In such a case, the present invention can be applied to the translucent member 1.

  In addition, as the base material 10 of the translucent member 1, sapphire having high hardness is suitable, but use of quartz glass, soda glass, or the like may also be considered.

The translucent member 1 of the present invention is not limited to the cover member used in the timepiece 100, but is information in various devices such as a mobile phone, a portable information device, a measuring device, a digital camera, a printer, a diving computer, and a pulse meter. It can be suitably used as a cover member for the display unit.
In addition, the translucent member 1 of this invention is not limited to a cover member. The 1st functional layer 11 and the 2nd functional layer 12 which concern on this invention are formed in the arbitrary locations in which the hardness ensuring and the antireflection function are requested | required in the base material 10 of the translucent member 1. FIG.

[Example]
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples at all.

[Change in characteristics of DLC layer depending on hydrogen content]
The sapphire glass as the substrate 10 was immersed in hot sulfuric acid at 120 ° C. for 10 minutes, rinsed thoroughly with pure water, and then dried in an air oven set at 120 ° C. for 30 minutes.
The cleaned substrate 10 was set in a CVD apparatus, and acetylene gas containing a predetermined concentration of hydrogen was introduced at 15.0 SCCM to a pressure of 0.2 mTorr. In this state, plasma was generated, and the DLC layer 13 as the first functional layer 11 was formed to have a thickness of about 120 nm.
Here, by using acetylene gases having different hydrogen contents, a plurality of translucent members 1 having different hydrogen contents with respect to the DLC layer 13 (the second functional layer 12 is not provided) were obtained.

These translucent members 1 were evaluated by the following methods.
Hydrogen concentration: The hydrogen concentration of the DLC layer 13 was measured using SIMS.
Refractive index: The refractive index of the DLC layer 13 was measured using an ellipsometer.
Color: The color of the DLC layer 13 was visually evaluated.
Surface hardness: A value obtained by measuring the surface hardness of the DLC layer 13 using a nanoindenter, and conforms to ISO14577.
The results of these evaluations are summarized in Table 1 below.

From Table 1, it was found that when the hydrogen content with respect to the DLC layer 13 is 20% or more in terms of atomic ratio, coloring of the DLC layer 13 can be prevented. In addition, it was found that the surface hardness of the DLC layer 13 can be a high hardness of 19600 N / mm ² or more if it is 50% or less. In general, if the surface hardness is 19600 N / mm ² or more, the scratch resistance of the surface is sufficient.

[Example 1]
The second functional layer 12 was formed by laminating Al ₂ O ₃ as follows on the translucent member 1 (the hydrogen concentration of the DLC layer 13 of 30%) that does not include the second functional layer 12 described above.
First, the translucent member 1 was set in a sputtering apparatus. After the inside of the chamber was set to 120 ° C. and 10 ⁻⁶ Torr, Ar gas was introduced at 9.0 SCCM and oxygen was introduced at 9.5 SCCM to obtain 0.2 mTorr. In this state, sputtering was performed by applying a sputtering power of 1500 W to the Al ₂ O ₃ target.
The second functional layer 12 thus formed had a thickness of 82 nm and a refractive index of 1.62. The first functional layer 11 had a thickness of 123 nm and a refractive index of 1.75.

[Comparative Example 1]
Under the same conditions as in Example 1, a transparent member 1 was obtained by laminating Al ₂ O ₃ (refractive index 1.62) directly on sapphire glass (refractive index 1.769).
[Reference example]
A single sapphire glass was used as the translucent member 1.

[Evaluation of transparent substrate]
The translucent member 1 of Example 1, Comparative Example 1 and Reference Example was evaluated as follows.
[Scratch resistance test 1: Cutter test]
The blade of the stationery cutter was applied perpendicularly to the surface of the base material, and the cutter blade was moved linearly along the surface of the base material while applying a load of 10 kg to the cutter. After performing the movement operation | movement of the blade of such a cutter 10 times, the presence or absence of the damage | wound on the surface of the translucent member 1 was observed with the stereomicroscope.
Those without scratches were OK, and those with scratches were NG.

[Scratch resistance test 2: sandfall test]
The following sandfall test is performed. The translucent member 1 was disposed at an inclination angle of 45 ° with respect to the horizontal plane. At this time, the translucent member 1 was arranged so that the side on which the first functional layer 11 and the second functional layer 12 were formed was the upper surface side. And the sand was dropped toward the translucent member 1 from the height of 1 m from the horizontal surface. Thereafter, the translucent member 1 is washed, and based on the difference ΔT (%) between the transmissivity of the translucent member 1 before the test and the transmissivity of the translucent member 1 after the test, The difficulty was evaluated.
The sand material used was carborundum produced by pulverizing and classifying black silicon carbide ingot and green silicon carbide ingot. In this test, 800 cm ³ of Carborundum # 24 having a center particle size of 600 to 850 μm was used.

[Surface roughness (Ra)]
The surface roughness (Ra) of the translucent member 1 was measured using a surface roughness measuring device (Talistep manufactured by Taylor Hobson).
[Reflectance]
The reflectance of standard light incident at an incident angle of 90 ° with respect to the surface of the translucent member 1 is obtained, and this reflectance is multiplied by the luminous sensitivity at an incident angle of 90 ° at each wavelength in the visible light region. It is a value calculated based on the integrated value of the combined values.
The results of these evaluations are summarized in Table 2 below.

From the results of the cutter test and the sand fall test, it was found that the translucent member 1 of Example 1 having the DLC layer 13 of the present invention had higher scratch resistance than Comparative Example 1 having no DLC layer 13. . Since the smooth DLC layer 13 is used as a base, the second functional layer 12 on the surface is also smoothed, and it is considered that the scratch is difficult to be damaged.
Moreover, since the translucency member 1 of Example 1 has a low reflectance compared with the reference example which is not provided with the 1st functional layer 11 and the 2nd functional layer 12, it turns out that it is excellent in antireflection property and visibility is high. It was.

[Example 2]
A translucent member 1 was produced in the same manner as in Example 1 except that the second functional layer 12 was formed using a SiO ₂ target.
The hydrogen content with respect to the DLC layer 13 was 30% in atomic ratio, and the thicknesses of the first functional layer 11 and the second functional layer 12 were 118 nm and 88 nm, respectively. Further, the refractive indexes were 1.75 and 1.46, respectively.

[Comparative Example 2]
Under the same conditions as in Example 2, a material obtained by laminating SiO ₂ directly on sapphire glass was used as translucent member 1.
The evaluation results of the translucent member 1 of Example 2 and Comparative Example 2 are shown in Table 3 below.

From the results of the cutter test and the falling sand test, it was found that the translucent member 1 of Example 2 provided with the DLC layer 13 of the present invention had higher scratch resistance than Comparative Example 2 provided with no DLC layer 13. . Since the smooth DLC layer 13 is used as a base, the second functional layer 12 on the surface is also smoothed, and it is considered that the scratch is difficult to be damaged.
Moreover, since the translucency member 1 of Example 2 has a low reflectance compared with the reference example which is not provided with the 1st functional layer 11 and the 2nd functional layer 12, it turns out that it is excellent in antireflection property and visibility is high. It was.

[Example 3]
Sapphire glass cleaned by the same method as described above was set in a sputtering apparatus.
Sputtering was performed under the same conditions as in Example 1 using a Ta ₂ O ₅ target, and Ta ₂ O ₅ was laminated on sapphire glass to form a first functional layer 11.
Then, the DLC layer 13 as the 2nd functional layer 12 was formed by the CVD method similar to the above, and the translucent member 1 was obtained.
The hydrogen content with respect to the DLC layer 13 was 50% in atomic ratio, and the thicknesses of the first functional layer 11 and the second functional layer 12 were 123 nm and 89 nm, respectively. The refractive indexes were 2.3 and 1.55, respectively.

[Comparative Example 3]
A material obtained by laminating DLC directly on sapphire glass under the same conditions as in Example 3 is referred to as translucent member 1.
The results of evaluation of the translucent member 1 of Example 3 and Comparative Example 3 are shown in Table 4 below.

  The translucent member 1 of Example 3 including the first functional layer 11 and the second functional layer 12 of the present invention is more reflective than Comparative Example 3 including only the DLC layer 13 and the reference example which is a single sapphire glass. Since the rate was low, it was found that the antireflection property was excellent and the visibility was high.

[Examples 4 to 18]
The translucent member 1 was produced in the same manner as in Example 3 except that the target used for sputtering of the first functional layer 11 and the thickness of the first functional layer 11 were changed as shown in Table 5 below.
The second functional layer 12 (DLC layer 13) had a refractive index of 1.6 and a thickness of 85 nm.

As is apparent from Table 5, Ta ₂ O ₅ , TiO ₂ , Gd ₂ O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , ZnO, ZrO ₂ , In ₂ O ₃ , Nd ₂ O ₃ , ThO ₂ , SnO ₂ , Sb ₂ O ₃ , CeO ₂ , Bi ₂ O _3, and HfO ₂ are the first functional layer 11 and the second functional layer 12 is the DLC layer 13, the translucent member 1 has scratch resistance. It was found that the visibility was excellent.

[Example 19 to Example 29]
The translucent member 1 was produced in the same manner as in Example 1 except that the target used for sputtering of the second functional layer 12 and the thickness of the second functional layer 12 were changed as shown in Table 6 below.
The first functional layer 11 (DLC layer 13) had a refractive index of 2.2 and a thickness of 124 nm.

Table 6 As is apparent, the first functional layer 11 and DLC layer _{13, SiO 2, MgF 2,} LiF, Na 3 AlF 6, NaF, CaF 2, LaF 3, NdF 3, Al 2 O 3, CeF 3 It was found that when any one of SiO and SiO was used as the second functional layer 12, the translucent member 1 was excellent in scratch resistance and visibility.

The figure which shows schematic layer structure of the translucent member which concerns on 1st Embodiment of this invention. Sectional drawing of the timepiece provided with the translucent member which concerns on 1st Embodiment as a cover glass. The figure which shows schematic layer structure of the translucent member which concerns on 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Translucent member, 3 ... Clock body, 4 ... Case, 10 ... Base material, 11 ... 1st functional layer, 12 ... 2nd functional layer, 13 ... DLC layer, 100 ... Clock

Claims (9)

A substrate having translucency,
A first functional layer formed on the substrate;
A second functional layer formed on the first functional layer,
The refractive index of the second functional layer is smaller than the refractive index of the first functional layer,
Either one of the first functional layer and the second functional layer is a DLC (diamond-like carbon) layer. The translucent member according to claim 1,
The difference between the refractive index of the first functional layer and the refractive index of the second functional layer is 0.1 or more,
The translucent member, wherein the second functional layer has a refractive index of 1.7 or less. In the translucent member of Claim 1 or Claim 2,
The translucent member, wherein at least one of hydrogen and fluorine is added to the DLC layer. In the translucent member of Claim 3,
The total content of hydrogen and fluorine in the DLC layer is 20% to 50% in atomic ratio. In the translucent member in any one of Claim 1 thru | or 4,
The first functional layer is the DLC layer;
The second functional layer is made of at least one of SiO ₂ , MgF ₂ , LiF, Na ₃ AlF ₆ , NaF, CaF ₂ , LaF ₃ , NdF ₃ , Al ₂ O ₃ , CeF ₃ and SiO. A translucent member characterized by the above. In the translucent member in any one of Claim 1 thru | or 4,
The first functional layer includes Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , MgO, Gd ₂ O ₃ , La ₂ O ₃ , Pr ₆ O ₁₁ , ZnO, ZrO ₂ , In ₂ O ₃ , Nd ₂ O. ₃ , ThO ₂ , SnO ₂ , Sb ₂ O ₃ , CeO ₂ , Bi ₂ O ₃ and HfO ₂ ,
The translucent member, wherein the second functional layer is the DLC layer. In the translucent member in any one of Claim 1 thru | or 6,
The thickness of the DLC layer is 5 nm or more and 150 nm or less. In the translucent member in any one of Claim 1 thru | or 7,
The thickness of the first functional layer and the thickness of the second functional layer are both 5 nm or more and 150 nm or less. A timepiece comprising the translucent member according to claim 1,
The translucent member is provided in a case that accommodates a watch body.

Images