JP2021148623A - Dial face for timepiece with solar cell and timepiece with solar cell - Google Patents

Abstract

To provide a dial face for a timepiece with a solar cell, on which a design based on color difference is shown while the transparency is being secured.SOLUTION: A dial face 10 includes a polarizer 11, a phase difference plate 12, and a cholesteric structure layer 13. The polarizer 11 draws out a straight polarization. The phase difference plate 12 is arranged on a back surface side of the polarizer 11 and changes the linear polarization into a round polarization. The cholesteric structure layer 13 is a film laminated on a support member and selectively arranged in a colored part for providing a predetermined color phase, the film being also a wavelength selective reflection film which reflects the component of the color phase of an incident light to the dial face 10 and can transmit the rest of the incident light.SELECTED DRAWING: Figure 3

Description

The present invention relates to a dial for a timepiece with a solar cell and a timepiece with a solar cell.

In a clock with a solar cell, a dial having light transmission is used in order to allow light to enter the solar cell. Solar cells have a distinctive deep purple color, and if the solar cells can be seen through the dial, they can be aesthetically unpleasant. Regarding this point, a configuration has been proposed in which a polarizing plate and a circularly polarized light retardation plate are arranged in front of the solar cell to suppress the reflected light from the solar cell while ensuring the transmitted light to the solar cell. Therefore, it is possible to provide a clock having a design in which the solar cell is difficult to see on the exterior.

Japanese Unexamined Patent Publication No. 11-23738 Japanese Unexamined Patent Publication No. 11-14716

The dial on which the polarizing plate and the circularly polarized light retardation plate are arranged on the front surface of the solar cell basically looks black. In order to widen the range of dial design, I would like to color the dial. In this respect, if the color is simply painted, there is a problem that the transmitted light to the solar cell is reduced and the power generation efficiency can be significantly reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a dial having light transmission and a design due to a difference in color, and a timepiece with a solar cell using the dial. And.

(1) The dial for a clock with a solar cell according to the present invention is a dial having light transmission and a design due to a difference in color, and is arranged on a polarizing plate and the back surface side of the polarizing plate. Of the incident light on the dial, which is a retardation plate that converts linearly polarized light into circularly polarized light and a film laminated on a support member, which is selectively arranged in a colored portion having a predetermined hue in the above design. It has a wavelength-selective polarizing film that can reflect the components of the hue and transmit the remaining components.

(2) In the dial for a timepiece with a solar cell according to the above (1), the wavelength-selective reflective film may be configured such that the retardation plate is used as the support member and is laminated on the back surface thereof. ..

(3) In the dial for a timepiece with a solar cell according to the above (1) and (2), the wavelength-selective reflective film may be configured to be a cholesteric structural layer coated on the support member. ..

(4) In the dial for a watch with a solar cell according to (1) above, the wavelength-selective reflective film is a cholesteric structural layer coated on the back surface of the retardation plate as the support member. The rotation direction of the circularly polarized light emitted from the back surface of the retardation plate and the rotation direction of the circularly polarized light of the light reflected by the cholesteric structure layer can be set to be the same.

(5) In the dial for a watch with a solar cell according to the above (3) and (4), the wavelength-selective reflective film has a shade related to the hue in the design due to a change in the thickness of the cholesteric structural layer. It can be a resulting configuration.

(6) The clock with a solar cell according to the present invention is a clock having a dial according to any one of (1) to (5) above and a solar cell arranged behind the dial. Therefore, the solar cell includes a power generation region that generates power in response to light incident and a non-power generation region that does not generate power, and the non-power generation region has the wavelength-selective reflective film arranged in the dial. It is placed in a position that does not overlap with the non-reflective film area.

(7) In the timepiece with a solar cell according to the above (6), the non-reflective coating region can be configured to include at least an hour character provided on the dial.

According to the present invention, it is possible to obtain a clock with a solar cell in which a design such as a pattern by coloring is applied while suppressing a decrease in power generation efficiency.

It is a top view which looked at the dial of the wristwatch which concerns on embodiment of this invention from the view side. It is a schematic plan view which shows the simplified pattern of the colored part and the black part in the dial of a wristwatch. FIG. 3 is a schematic partial cross-sectional view taken along the line III-III of FIG. 2 of the wristwatch according to the first embodiment. 2 is a schematic partial cross-sectional view taken along the line III-III of FIG. 2 of the wristwatch according to the second embodiment.

Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. In all the drawings for explaining the embodiment, the members having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted.

[First Embodiment]
FIG. 1 is a plan view of the dial of the wristwatch 1 according to the first embodiment as viewed from the viewing surface side. The visible surface is a surface that the user visually recognizes when using the wristwatch 1, that is, a front surface, and the opposite surface is the back surface. Hereinafter, the front-back direction or the up-down direction is defined with the viewing surface side as the front surface or the upper surface.

The wristwatch 1 includes a dial 10 which is a visual recognition member and a solar cell 30. The alternate long and short dash line in FIG. 1 shows the outer shape and the dividing line D of the solar cell 30 arranged on the back surface side of the dial 10. Although not shown in FIG. 1, it is preferable that the pointer is arranged on the dial 10 so as to move the hands.

On the visible surface side of the dial 10, a time character 50 indicating the time, a logo mark indicating a brand name, a product name, etc., and a display unit 60 displaying other patterns and the like are provided. In FIG. 1, Roman letters I to XII are shown as hour letters 50, and “ABCDEFG” indicating a brand name and a mark consisting of a black triangle and a quadrangle are displayed as a display unit 60.

In the following description, the chromatic region of the dial 10 is referred to as a colored portion CL, and the dark region recognized by the user as black is referred to as a black portion BK. In the wristwatch 1 shown in FIG. 1, the area where the hour character 50, the display unit 60, etc. are provided is the black portion BK, and the region other than the black portion BK is the coloring portion CL. In the present embodiment, the hue of the coloring portion CL is blue.

Incidentally, FIG. 1 shows an example of the dial 10 in which about 86% of the visual recognition surface is the colored portion CL and about 14% is the black portion BK. The shape and design of the dial 10 shown in FIG. 1 is an example, and is not limited to this, and may include at least the colored portion CL and the black portion BK.

Next, the cross-sectional structure of the dial 10 will be described. Here, the patterns of the colored portion CL and the black portion BK on the visual plane of the dial 10 are simplified to obtain a schematic plan view shown in FIG. Incidentally, the black portion BK in FIG. 2 schematically represents the hour character 50. FIG. 3 is a schematic partial cross-sectional view of the wristwatch 1 on lines III-III of FIG. 2, showing a vertical cross-sectional structure of the dial 10 and the solar cell 30.

The dial 10 is arranged in front of the solar cell 30 and has a laminated structure including a polarizing plate 11, a retardation plate 12, and a cholesteric structure layer 13. In the present embodiment, the dial 10 further includes a prism layer 14 and a thickness adjusting layer 15, and the prism layer 14 has a thickness from the front side (upper side in FIG. 3) to the back side (lower side in FIG. 3). It is a laminated structure in which the adjusting layer 15, the cholesteric structure layer 13, the polarizing plate 11, and the retardation plate 12 are arranged in this order.

The polarizing plate 11 is a linear polarizing plate. That is, the polarizing plate 11 has a transmission axis and an absorption axis orthogonal to the transmission axis, absorbs and removes a component in the absorption axis direction from the incident light, and extracts linearly polarized light in the transmission axis direction.

The retardation plate 12 changes the linearly polarized light into circularly polarized light. Specifically, the retardation plate 12 is a 1/4 wave plate, typically made of a birefringent material such as a stretched film or a liquid crystal film, and its optical axis and the polarization direction of the emitted light of the polarizing plate 11. It is arranged so that the angle θ formed by the light crystal is 45 °. By combining the polarizing plate 11 and the retardation plate 12, circularly polarized emitted light can be obtained from the retardation plate 12 to the rear with respect to the incident light from the front to the polarizing plate 11.

The cholesteric structure layer 13 is made of a cholesteric liquid crystal display, and functions as a wavelength-selective reflective film capable of reflecting the hue component of the coloring portion CL of the incident light on the dial 10 and transmitting the remaining component. The cholesteric liquid crystal has a laminated structure in which layers of molecules arranged in one direction are stacked, and the molecular arrangement direction is gradually twisted along the overlapping direction of the layers, whereby a spiral structure having a fixed period is formed in the laminated structure. It is formed. Due to this structure, the cholesteric structure has the property of reflecting circularly polarized light having the same wavelength as the product of the period of the helix and the refractive index and in the same direction as the winding of the helix. The cholesteric structure layer 13 is formed so that the spiral axis is along the front-rear direction and reflects blue light, which is the hue attached to the coloring portion CL.

The thickness adjusting layer 15 is a plate-shaped member for adjusting the thickness of the dial 10, and is made of a material having high transparency with respect to light in the visible light wavelength range. In the present embodiment, the thickness adjusting layer 15 is used as a support member for the cholesteric structure layer 13, and the cholesteric structure layer 13 is formed on the back surface of the thickness adjusting layer 15. The cholesteric structure layer 13 can be formed on the back surface of the thickness adjusting layer 15 by coating, and the colored portion CL of the dial 10 is selectively cholesteric by using printing techniques such as inkjet, gravure printing, and flexographic printing. The structural layer 13 is formed. Therefore, with respect to the dial 10 of FIG. 2, the cholesteric structural layer 13 is not formed because the portion of the hour character 50 existing at two locations in the cross section of FIG. 3 is the black portion BK, and the other portions The cholesteric structural layer 13 is formed only in a certain colored portion CL.

The prism layer 14 is formed on the front surface of the thickness adjusting layer 15 with, for example, a resin having high transparency with respect to light in the visible light wavelength range. The prism layer 14 has a large number of irregularities having a triangular vertical cross section, and its surface forms, for example, triangular grooves such as a straight line, a spiral shape, and a concentric circle shape in the plane of the dial 10. For example, the apex angles of the triangles aligned with the cross section of the prism layer 14 are formed at right angles. A part of the light incident on the dial 10 is reflected forward by total reflection on the surface of the triangular groove of the prism layer 14. As a result, the brightness of the surface of the dial 10 can be increased, the surface can be given a metallic texture (gloss, color, etc.), and the decorativeness of the dial 10 can be improved.

According to the structure of the dial 10 shown in FIG. 3, in the coloring portion CL, the cholesteric structure layer 13 is a blue component of the light incident from the front and transmitted through the prism layer 14 and the thickness adjusting layer 15 in a clockwise direction. Alternatively, it reflects either one of the counterclockwise circularly polarized light components. As a result, the coloring unit CL exhibits a blue color to the user who visually recognizes the dial 10.

On the other hand, in the black portion BK, since the cholesteric structure layer 13 does not exist, the blue component is not reflected, and the light incident from the front and transmitted through the prism layer 14 and the thickness adjusting layer 15 is the polarizing plate 11 and the retardation plate 12. And enter the solar cell 30. This incident light is used for power generation in the solar cell 30. Here, a part of the incident light can be reflected on the surface of the solar cell 30, but the direction of circularly polarized light in the reflected light is opposite to that of the incident light, and the reflected light is polarized by the retardation plate 12. It becomes linearly polarized light in the absorption axis direction of the plate 11. Therefore, this reflected light is blocked by the polarizing plate 11. That is, since the polarizing plate 11 and the retardation plate 12 basically do not transmit the light reflected by the solar cell 30 forward, the black portion BK exhibits black color to the user who visually recognizes the dial 10.

The light that is not reflected by the cholesteric structure layer 13, that is, the components of colors other than blue and the circularly polarized light components that are blue and are not reflected pass through the cholesteric structure layer 13, the polarizing plate 11, and the retardation plate 12 to the solar cell 30. It is incident and used for power generation by the solar cell 30. That is, by using the cholesteric structure layer 13, the dial 10 can be colored while suppressing a decrease in power generation efficiency. Further, in the black portion BK, the amount of incident light on the solar cell 30 increases because there is no reflection on the cholesteric structure layer 13. Therefore, according to the dial 10 of the present embodiment, the cholesteric structure layer is selectively formed in the plane of the dial 10 by printing or the like, so that the pattern is due to the difference in color between the colored portion CL and the black portion BK. Etc. can be applied, high designability can be realized, and a part without a cholesteric structural layer can be made, as compared with the case where the cholesteric structural layer is uniformly provided over the entire in-plane of the dial 10. It is possible to realize the watch 1 in which the transmittance of the dial 10 is increased and the decrease in the power generation efficiency of the solar cell 30 is suppressed.

By the way, the solar cell 30 may include a power generation region that generates power with respect to the incident light and a non-power generation region that does not generate power. Specifically, the solar cell 30 is divided into four power generation regions by the dividing line D, and a non-power generation region is provided along the dividing line D as a boundary between these regions. In order to suppress a decrease in the power generation efficiency of the solar cell 30, the non-power generation region is a non-reflective coating region in which the wavelength-selective reflective coating is not arranged in the dial 10, that is, the black portion BK in which the cholesteric structural layer 13 is not arranged. It is preferable to arrange it at a position where it does not overlap with.

As described above, the design of the dial 10 in FIG. 1 is an example, and the larger the proportion of the black portion BK, the more the power generation efficiency can be improved. For example, in the design of FIG. 1, if the colored portion CL and the black portion BK are reversed, the power generation efficiency is increased.

[Second Embodiment]
The wristwatch 1 according to the second embodiment of the present invention has a difference in the structure of the dial 10 from the first embodiment, and both embodiments are basically common in other respects. Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment. In the following description of the present embodiment, the dial is represented by the reference numeral “10B” and the cholesteric structure layer is represented by the reference numeral “13B” in order to facilitate the distinction from the first embodiment.

The plan view of the dial 10 of FIGS. 1 and 2 can be used for the dial 10B of the present embodiment, and the design is composed of the colored portion CL and the black portion BK. For example, the hour character 50 is the black portion BK. Is.

FIG. 4 is a schematic partial cross-sectional view taken along line III-III of FIG. 2 for the wristwatch 1 according to the second embodiment, and similarly to FIG. 3 of the first embodiment, the dial 10B and the solar cell 30 Shows the vertical cross-sectional structure of.

The dial 10B is arranged in front of the solar cell 30 and has a laminated structure including a polarizing plate 11, a retardation plate 12, and a cholesteric structure layer 13B. The dial 10B of the present embodiment has a laminated structure in which the polarizing plate 11, the retardation plate 12, and the cholesteric structure layer 13B are arranged in this order from the front side (upper side in FIG. 4) to the back side (lower side in FIG. 4). Is. In this structure, the retardation plate 12 serves as a support member for the cholesteric structure layer 13B, and the cholesteric structure layer 13B is laminated on the back surface of the retardation plate 12. As in the first embodiment, the cholesteric structure layer 13B is selectively formed on the colored portion CL by coating or the like, and the portion of the hour letter 50 existing at two locations in the cross section of FIG. 4 is the black portion BK. Therefore, the cholesteric structural layer 13B is not formed.

By combining the polarizing plate 11 and the retardation plate 12, as in the first embodiment, with respect to the incident light from the front side to the polarizing plate 11, the emitted light of circularly polarized light from the retardation plate 12 toward the back surface side. Is obtained. In the present embodiment, it is assumed that the polarizing plate 11 and the retardation plate 12 are arranged so that the circularly polarized light becomes clockwise circularly polarized light at θ = 45 °. Correspondingly, the cholesteric structural layer 13B is formed so as to reflect the clockwise circularly polarized light among the blue components.

In this configuration, the clockwise circularly polarized light component of the light incident on the coloring portion CL is incident on the cholesteric structure layer 13B, and the blue color of the component is reflected by the cholesteric structure layer 13B. The reflected light in the cholesteric structure layer 13B is clockwise circularly polarized light, and the retardation plate 12 is linearly polarized light in the transmission axis direction of the polarizing plate 11. Therefore, this reflected light passes through the polarizing plate 11. That is, since the polarizing plate 11 and the retardation plate 12 basically transmit the blue reflected light from the cholesteric structure layer 13B forward, the coloring portion CL exhibits blue color to the user who visually recognizes the dial 10B.

On the other hand, in the black portion BK, since the cholesteric structural layer 13B does not exist, the blue component is not reflected, and as described in the first embodiment, the polarizing plate 11 and the retardation plate 12 are the solar cells 30. Since the reflected light in the above is basically not transmitted forward, the black portion BK exhibits black color to the user who visually recognizes the dial 10B.

Light other than blue, which is not reflected by the cholesteric structure layer 13B, enters the solar cell 30 and is used for power generation by the solar cell 30.

Similar to the first embodiment, the dial 10B of the present embodiment can also color the dial while suppressing a decrease in power generation efficiency, and the black portion BK has no reflection at the cholesteric structure layer 13B. Therefore, the amount of light incident on the solar cell 30 increases. That is, also in the present embodiment, as in the first embodiment, it is possible to design a pattern or the like due to the difference in color between the colored portion CL and the black portion BK, and it is possible to realize high designability and print or the like. By selectively forming the cholesteric structural layer in the in-plane of the dial 10B, a portion without the cholesteric structural layer can be formed, and when the cholesteric structural layer is uniformly provided in the entire in-plane of the dial 10B. Compared with this, it is possible to realize the watch 1 in which the transmittance of the dial 10B is increased and the decrease in the power generation efficiency of the solar cell 30 is suppressed.

By the way, FIG. 4 shows an example in which the thickness of the cholesteric structure layer 13B in the colored portion CL is not uniform and changes. Specifically, the thickness of the cholesteric structural layer 13B in the region surrounded by the 12 hour letters 50 in FIG. 2 becomes thinner toward the center of the region in the cross-sectional view of FIG. Such a change in thickness can be realized by changing the coating amount when the cholesteric structure layer 13B is formed by, for example, an inkjet or the like depending on the location, and the change in thickness is related to the hue in the colored portion CL. It can produce shades. Specifically, in the example of FIG. 4, the cholesteric structural layer 13 is thick at the portion near the outer edge of the dial 10B, and the blue color appears deep at the portion. On the other hand, in the region surrounded by the hour letter 50, as the cholesteric structural layer 13B becomes thinner toward the center of the dial 10B, the blue color becomes lighter and the blackness increases, and a design having a gradation in saturation can be realized. For such shading / gradation, instead of changing the thickness of the cholesteric structure layer, the print density is adjusted by adjusting the size and spacing of the halftone dots when the cholesteric structure layer is formed by halftone dot printing. It can also be realized by changing it. The gradation can also be applied to the first embodiment.

Further, as in the first embodiment, in the present embodiment as well, in order to suppress the decrease in power generation efficiency, it is preferable that the non-power generation region of the solar cell 30 is arranged at a position that does not overlap with the black portion BK.

Further, in the present embodiment, the tint of the coloring portion CL can be adjusted by changing the phase difference generated in the retardation plate 12. For example, by changing the phase difference in the plane of the dial 10B, it is possible to give a color width with respect to the blue presented in the plane.

Further, the hue of the coloring portion CL can be increased by changing the reflection wavelength of the cholesteric structure layer. Specifically, in each of the above embodiments, the cholesteric structure layer 13 is configured to use only those that reflect blue, but even if a plurality of types of cholesteric structure layers that reflect different colors are arranged in the coloring portion CL. good. In that case, it is preferable to arrange solar cells corresponding to each color in the power generation region of the solar cell 30 or to provide a wavelength conversion layer to suppress a decrease in power generation efficiency.

In each of the above embodiments, the configuration in which the cholesteric structural layer 13 functions as a wavelength-selective reflective film has been described, but a dielectric multilayer film may be used as the wavelength-selective reflective film instead of the cholesteric structural layer. ..

1 Wristwatch, 10,10B dial, 11 polarizing plate, 12 retardation plate, 13,13B cholesteric structure layer, 14 prism layer, 15 thickness adjustment layer, 30 solar cells, 50 o'clock character, 60 display unit.

Claims (7)

A dial for a watch with a solar cell that has light transmission and a design due to the difference in color.
Polarizing plate and
A retardation plate arranged on the back surface side of the polarizing plate to convert linearly polarized light into circularly polarized light,
A film laminated on a support member, which is selectively arranged in a colored portion having a predetermined hue in the design, reflects a component of the hue among the incident light on the dial, and transmits the remaining component. Possible wavelength selective reflective film and
A dial characterized by having. The dial for a timepiece with a solar cell according to claim 1, wherein the wavelength-selective reflective film has the retardation plate as the support member and is laminated on the back surface thereof. The dial for a watch with a solar cell according to claim 1 or 2, wherein the wavelength-selective reflective film is a cholesteric structural layer coated on the support member. The wavelength-selective reflective film is a cholesteric structure layer coated on the back surface of the retardation plate as the support member.
The rotation direction of the circularly polarized light emitted from the back surface of the retardation plate and the rotation direction of the circularly polarized light of the light reflected by the cholesteric structure layer are set to be the same.
The dial for a timepiece with a solar cell according to claim 1. The character for a timepiece with a solar cell according to claim 3 or 4, wherein the wavelength-selective reflective film produces shades related to the hue in the design due to a change in the thickness of the cholesteric structural layer. Board. A timepiece with a solar cell having the dial according to any one of claims 1 to 5 and a solar cell arranged behind the dial.
The solar cell includes a power generation region that generates power in response to light incident and a non-power generation region that does not generate power.
The non-power generation region is arranged at a position in the dial that does not overlap with the non-reflective coating region on which the wavelength-selective reflective coating is not arranged.
A watch that features. The timepiece with a solar cell according to claim 6, wherein the anti-reflective coating region includes at least an hour character provided on the dial.

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