JPS631270Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electronic watch powered by a solar cell.

Since electronic watches require batteries as a power source, they are expensive to use, and replacing batteries is troublesome. For this reason, there is a demand for electronic watches equipped with solar cells as a power source. As the solar cell, it is considered to use a conventionally produced crystalline silicon solar cell. In this crystalline silicon solar cell, a pn junction is formed on one side of a thick silicon plate for mechanical strength reasons, and power is generated using incident light from that side. The light-receiving surface of such a crystalline silicon solar cell is only on one side. Electronic watches equipped with such solar cells have the disadvantage that they have restrictions on where they can be installed because the light-receiving surface of the solar cell must be directed toward the light source.

The purpose of this invention is to eliminate the above-mentioned drawbacks and provide an electronic timepiece with fewer restrictions on the installation location.

According to this invention, the above object has been achieved by an electronic timepiece characterized in that it is equipped with an amorphous solar cell formed on a transparent substrate and which generates electricity using incident light from both sides as a power source.

Examples of this invention will be described below based on the drawings. FIG. 1 is a front view of an electronic timepiece according to an embodiment of this invention, and FIG. 2 is a side view of FIG. 1. A transparent glass disc-shaped substrate 2 is vertically attached to a support stand 1, and an electronic clock module 3 is attached to the center of the substrate 2. Electronic clock module 3
A solar cell 4 made of a thin film of amorphous silicon is formed on the surface of the outer substrate 2 to which the solar cell 4 is attached. As shown in the circuit diagram of FIG. 3, a storage battery 5 is connected in parallel to the electronic clock module 3, and an amorphous silicon solar cell 4 is connected to this parallel connection via a diode 6. There is. As shown in the cross-sectional view of FIG. 4, the amorphous silicon solar cell 4 includes a transparent conductive film 7 formed on the surface of the substrate 2 and made of, for example, indium or tin oxide;
Thereon, an n-type amorphous silicon film 8, an intrinsic amorphous silicon film 9, and a p-type amorphous silicon film 10 are sequentially formed by decomposing monosilane doped with impurities as necessary by glow discharge. p-i-
It consists of an n-layered film and a transparent conductive film 11 formed thereon. Both the n-type semiconductor film 8 and the p-type semiconductor film 10 are thin films that allow light to pass through. Therefore, in this solar cell 4, incident light from both sides of the transparent conductive films 7 and 11 is transmitted. The electrons reach the intrinsic semiconductor film 9 and generate electron-hole pairs to generate electricity. The generated power is supplied to the electronic timepiece module 3 via the transparent conductive films 7 and 11 serving as electrodes, and the excess power is stored in the storage battery 5. Storage battery 5
is the electronic clock module 3 in Figures 1 and 2.
It is not particularly shown in the figure.

In such a configuration, during the daytime, the clock is driven while charging the storage battery 5 with the power generated by the solar cell, but at night, when photovoltaic power is not available, the clock is maintained by discharging from the storage battery 5. . Therefore, if the capacity of the solar cell 4 is determined so that the amount of charge of the storage battery 5 is greater than the amount of discharge during the night, this electronic timepiece will continue to be driven until the life of the parts ends. The diode 6 prevents backflow from the storage battery 5 when the solar cell 4 is not generating power, and is biased in the forward direction and conducts current when the solar cell 4 is generating power. Since the smaller the forward voltage drop at this time, the better, germanium or Schottky barrier diodes are more convenient than silicon diodes.

As mentioned above, in this electronic clock that does not require battery replacement, the solar cell generates electricity using light incident from both sides, so for example, it can be attached to a window and utilizes external light from the back and light scattered by indoor walls from the front. By doing so, it is possible to save the solar cell area for the required clock drive power, which is also economically advantageous. Additionally, since both sides are used for light reception, there are fewer restrictions on installation location. In addition, since an amorphous semiconductor film of any shape can be formed on a transparent substrate, it is also possible to provide decorative properties.

[Brief explanation of the drawing]

Figure 1 is a front view of an electronic timepiece according to an embodiment of this invention, Figure 2 is a side view of Figure 1, and Figure 3 is a side view of Figure 1.
FIG. 4 is a sectional view of the solar cell shown in FIG. 1. 2...Substrate, 4...Solar cell.

Claims (1)

[Scope of utility model registration request] A transparent substrate is attached to a support base, an electronic clock module is attached approximately to the center of the back side of the substrate so that the time display surface faces the front side, and a transparent electronic clock module is attached to the back side of the substrate in order so as to surround the clock module. It is formed by laminating a conductive film, an amorphous silicon film with a pin junction, and other transparent conductive films, and includes a plurality of solar cells connected in series to each other, and the cells are connected to a substrate and other transparent conductive films. An electronic timepiece characterized in that it is possible to utilize light incident through a membrane and to supply power to the module.