Horology: time measuring systems or devices – Chronological – With mechanical or electromechanical driven display
Reexamination Certificate
2001-05-25
2004-09-14
Miska, Vit (Department: 2859)
Horology: time measuring systems or devices
Chronological
With mechanical or electromechanical driven display
C368S082000, C368S205000
Reexamination Certificate
active
06791905
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a timepiece comprising a time display unit for displaying time and a calendar, and a solar cell for generating electric power utilizing light as an energy source, wherein electric power generated by the solar cell is used as an energy source for displaying time on the time display unit.
BACKGROUND TECHNOLOGY
A battery has been in use traditionally as a power source of an electronic wrist watch and the like, however, owing to inconvenience in replacement of the battery and needs to overcome environmental pollution problems and so forth caused by waste batteries, there has recently come to be commercially available and in widespread use an electronic wrist watch wherein needs of replacing a battery are eliminated by assembling therein a solar cell, a secondary cell, and a charge-discharge control circuit for the secondary cell.
With a timepiece incorporating such a solar cell as power generation means, electric power generated by the solar cell through conversion of radiated optical energy into electric energy is stored in the secondary cell, and a clock circuit and so forth, and a stepping motor or a liquid crystal display panel are driven by the electric power as stored, thereby displaying time and calendar information in the form of analog display by use of a dial and hands, or digital display by use of the liquid crystal display panel.
The solar cell incorporated in such a timepiece is provided with power generation units, each formed by a first electrode, an optical power generation layer, and a second electrode that are stacked up in that order on a solar cell substrate in such a way as to be superimposed on each other. The solar cell substrate has transmitting portions, however, the transmitting portions are provided for the purpose of separating the power generation units from each other or connecting the same with each other, but not for positively ensuring transmitting property.
Accordingly, assuming that the visible side (a viewer's side) of a time display unit of the timepiece is referred to as the front side while the back cover side thereof is referred to as the rear side, the solar cell is generally disposed on the rear side of the time display unit, or on the periphery thereof.
Further, a configuration of the timepiece has been proposed such that in order to shield a color of the solar cell substrate detrimental to a design feature of the timepiece incorporating the solar cell, or to shield a pattern of the power generation units, a shielding film such as a white diffusing film, a color diffusing film, a color filter, and so forth are disposed on the front side of the solar cell substrate, thereby shielding the solar cell substrate so as not to be directly visible.
In the case of installing the solar cell on the underside of the time display unit of the timepiece, however, it becomes necessary to keep a proper balance between the design feature and power generation efficiency because the solar cell substrate becomes visible through the time display unit or the shielding film is used on top of the solar cell substrate in order to shield the solar cell substrate. Use of a shielding film having a large optical absorption coefficient results in considerable deterioration of the power generation efficiency while use of a shielding film having a small optical absorption coefficient results in deterioration of the shielding effect of the solar cell substrate.
Further, in the case of installing the solar cell on top of the time display unit, the design feature of the timepiece would be largely dependent on a color and shape of the power generation units because, in this case, the transmitting portions only are installed over the time display unit without the power generation units installed thereon, and the power generation units are installed on the periphery of the time display unit for generation of electric power.
In this case as well, it is possible to shield a color tone or the pattern of the power generation units by installing a shielding film on top of the power generation units of the solar cell, however, in such a case, due to an increase in the difference of transmittance between the surface of the time display unit and the power generation units, the power generation units of the solar cell is distinctly recognized against the transmitting portions thereof, thereby subjecting the design feature of the timepiece to some constraints.
The invention has been developed to solve the problems described above encountered in the case of a timepiece provided with a solar cell, and it is therefore an object of the invention to provide a timepiece wherein visibility of a time display unit is not impaired even if the solar cell in whole, including power generation units, is installed on the visible side of the time display unit of the timepiece, and power generation units can be rendered inconspicuous so as not to introduce restrictions on the design feature of the timepiece even if no shielding film is installed, while ensuring satisfactory power generation efficiency of the solar cell.
DISCLOSURE OF THE INVENTION
To this end, a timepiece according to the invention comprises a time display unit, and a solar cell comprised of a solar cell substrate, and a power generation unit having at least a first electrode, a photovoltaic layer, and a second electrode, stacked up in that order so as to be superimposed on each other on the solar cell substrate, using electric power generated by the solar cell as an energy source for executing time display in the time display unit; said solar cell comprising a plurality of patterned power generation units provided on the solar cell substrate composed of a transparent material, and transmitting portions having a large transmittance in the visible light range and provided between the plurality of the patterned power generation units, wherein the solar cell is disposed on the visible side of the time display unit so as to be superimposed on the time display unit, the power generating units and the transmitting portions are superimposed on the time display unit, and the time display region is rendered to be recognized through the transmitting regions.
In the case of the time display unit being an analog time display unit having a dial and hands, the solar cell may be disposed on a visible side of the dial.
Or the solar cell may be disposed between the dial and the hands.
Otherwise, the solar cell is preferably provided with the plurality of the patterned power generation units being connected with each other via the respective first electrodes and the respective second electrodes, and the solar cell is preferably disposed between the time display unit and a glass of the timepiece so as to be superimposed on the time display unit.
The solar cell may have regions where transmittance of partial power generation and transmitting units comprised of the respective power generation units in combination with the respective transmitting portions is in a range of 30 to 80%, thereby enabling a condition on the underside of the solar cell substrate to be seen in the regions from a viewer's side.
Further, the solar cell may be constructed such that an area ratio of the respective power generation units installed on the solar cell substrate to the respective transmitting portions adjoining the respective power generation units varies depending on a region on the solar cell substrate.
The solar cell may be constructed such that a plurality of solar cell substrates which vary in area ratio of the respective power generation units installed thereon to the respective transmitting portions adjoining the respective power generation units, are disposed therein.
Otherwise, the solar cell may be constructed such that a plurality of solar cell substrates, each having the power generation unit and the transmitting portion, are stacked up one after another, and are disposed such that transmitting portions of the plurality of the solar cell substrates are superimposed on each other.
A printed layer having n
Citizen Watch Co. Ltd.
Miska Vit
Westerman Hattori Daniels & Adrian LLP
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