JP2012202931A - Power supply device and electronic timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device having stable current output characteristics even when solar cells are shaded and to provide an electronic timepiece.SOLUTION: A power supply device comprises: a plurality of cells 11A to 11D connected in series which receive light and convert it to power; switches SWA to SWD which are connected in parallel to the plurality of the cells, respectively; a volt meter 22 which measures the voltage of the plurality of cells that are connected in series; and a control part 23 which sequentially opens and closes the switches and detects the cell of which shaded area is the largest based on the voltage value measured by the volt meter.

Description

  The present invention relates to a power supply device and an electronic timepiece using solar cells.

  As a technique of an electronic timepiece using a thin film solar cell in which a plurality of photoelectric conversion cells are connected in series, there is one described in Patent Document 1, for example. The configuration of the solar panel of this type of electronic timepiece is shown in FIG.

  The solar panel shown in FIG. 11 has, for example, four solar cells 101, 102, and 103 in a circumferential direction of an opening 110 that is substantially the center of the substrate on a substrate made of a substantially circular metal having an insulating film on the surface. , 104 are arranged in series. The drive shaft of the watch pointer 120 passes through the opening 110.

JP 2001-15781 A

  In the invention described in Patent Document 1, when a solar cell is shielded by the watch hand 120, the photovoltaic power of the cell is reduced by the shielded area. That is, the light-shielded cell behaves as a diode connected with the normal power generation direction of the cell as the reverse direction, and exhibits an extremely large resistance value. Therefore, when the photovoltaic power of one cell falls in this way, there is a problem that the output current of the entire solar cell module is greatly lowered and stable current output characteristics cannot be obtained.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a power supply device and an electronic timepiece that can obtain stable current output characteristics even when a solar cell is shielded from light.

  In order to achieve the above object, a power supply device according to the present invention includes a plurality of serially connected cells that receive light and convert it into power, a switch connected in parallel to each of the plurality of cells, and the plurality of the plurality of cells. A voltmeter that measures a voltage of cells connected in series; and a controller that sequentially opens and closes the switch and detects a cell having the largest light-shielding area based on a voltage value measured by the voltmeter. It is characterized by that.

  In the power supply device of the present invention, the control unit detects a cell having the largest light-shielding area by detecting a current flowing through each of the plurality of cells from a voltage value measured by the voltmeter. May be.

  In the power supply device of the present invention, the control unit may close a switch connected in parallel to the cell having the largest light shielding area.

  In the power supply device of the present invention, the control unit may close the switch that has been closed when the voltage value measured by the voltmeter becomes maximum.

  In the power supply device of the present invention, the control unit may detect the cell having the largest light shielding area in a first period corresponding to the number of the plurality of cells.

  The power supply device according to the present invention further includes a pointer driven on the plurality of cells according to a control signal of the control unit in a second period, and the plurality of cells are divided in a driving direction of the pointer. You may make it.

  The power supply device according to the present invention further includes an ammeter that measures a current of each of the plurality of cells, and the control unit sequentially opens and closes the switch, and a light shielding area based on a current value measured by the ammeter. The cell having the largest value may be detected.

  To achieve the above object, an electronic timepiece according to the present invention includes a plurality of serially connected cells that receive light and convert it into power, a switch connected in parallel to each of the plurality of cells, and the plurality of the plurality of cells. A voltmeter that measures a voltage of cells connected in series; and a controller that sequentially opens and closes the switch and detects a cell having the largest light-shielding area based on a voltage value measured by the voltmeter. It is characterized by that.

  In the electronic timepiece according to the aspect of the invention, the control unit may detect a cell having the largest light shielding area by detecting a current flowing through each of the plurality of cells from a voltage value measured by the voltmeter. May be.

  ADVANTAGE OF THE INVENTION According to this invention, the most light-shielded cell can be detected easily and accurately in the several solar cell of a power supply device. Thus, stable current output characteristics can be obtained by avoiding the use of the most shielded cell.

1 is an external perspective view of an electronic timepiece according to a first embodiment. It is a top view which shows the structural example of the solar panel in FIG. It is a block diagram which shows the structure of an electronic timepiece. It is a circuit diagram of the power supply device of the electronic timepiece in the first embodiment. It is a flowchart which shows the specific cell detection process in 1st Embodiment. It is a tabular form figure which shows the output voltage value at the time of the short circuit of each cell in 1st Embodiment. It is a principal part circuit diagram of the power supply device of the electronic timepiece in 2nd Embodiment. It is a table format figure which shows the output voltage value at the time of the short circuit of each cell in 2nd Embodiment. It is a top view which shows the structural example of the solar panel in 3rd Embodiment. It is a principal part circuit diagram of the power supply device of the electronic timepiece in 3rd Embodiment. It is a top view which shows the structural example of the conventional solar panel.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is an external perspective view of an electronic timepiece 10 according to the first embodiment of the present invention.
In FIG. 1, an electronic timepiece 10 includes a lower housing portion 10a and an upper housing portion 10b. The upper housing part 10b is provided with a dial 12 via a solar panel 11, and a circuit board such as a timepiece driving circuit is provided on the inner surface of the lower housing part 10a. A watch movement is installed between the lower housing portion 10a and the upper housing portion 10b, and a watch pointer shaft 13 connected to the watch movement is connected to the upper housing portion 10b, the solar panel 11, and the dial plate 12. It is the structure which penetrated each through-hole and protruded upwards.

  A time pointer 14 is attached to the clock pointer shaft 13. That is, the time hand 14 includes a second hand 15, a minute hand 16 and an hour hand 17. The clock pointer shaft 13 includes a second hand shaft, a minute hand shaft, and an hour hand shaft to which a second hand 15, a minute hand 16, and an hour hand 17 are attached, respectively. Reference numerals 18 and 19 denote button switches for operating a clock operation.

FIG. 2 is a plan view showing a configuration example of the solar panel 11 in FIG.
The solar panel 11 receives external light and converts it into electric power. A light emitting element (hereinafter simply referred to as an amorphous silicon semiconductor layer) is formed on a substrate made of a substantially circular metal having an insulating film on the surface. (Referred to as a cell). As shown in FIG. 2, the solar panel 11 is divided into four cells 11A, 11B, 11C, and 11D, and each of the cells 11A to 11D has an opening 13a at the substantially center of the solar panel 11 through which the clock pointer shaft 13 passes. Each is formed in a fan shape in the circumferential direction. That is, the four cells 11A, 11B, 11C, and 11D are divided in the driving direction of the time indicator 14 and connected in series.

FIG. 3 is a block diagram showing a configuration of the electronic timepiece according to the present embodiment, and FIG. 4 is a circuit diagram of a power supply device for the electronic timepiece according to the present embodiment.
As shown in FIG. 3, the electronic timepiece 10 includes a power supply device 20, a circuit block 30, and a timepiece movement 40. The power supply device 20 includes the solar panel 11 illustrated in FIG. 2, the switch unit 21, a voltmeter 22, a charge control circuit 23, and a secondary battery 24.

  As shown in FIG. 4, the switch unit 21 includes switches SWA, SWB, SWC, SWD connected in parallel to each of the four cells 11A to 11D. The voltmeter 22 is connected in series to the cells 11 </ b> A to 11 </ b> D and measures the voltage of the cell. The charge control circuit 23 outputs the control signal D1 to open and close the switches SWA to SWD in sequence, and based on the voltage value measured by the voltmeter 22, the cell having the largest light shielding area among the cells 11A to 11D is selected. It is a control part to detect.

Further, the charge control circuit 23 (control unit) stores the electromotive force generated in the solar panel 11 in the secondary battery 24 and adjusts the amount of storage. The charge control circuit 23 that performs such an operation includes, for example, a software configuration including a CPU, a RAM that is a work memory of the CPU, and a ROM that stores a control program including a specific cell detection process of FIG. It may be a hardware configuration including a logic circuit.
The secondary battery 31 of the watch body is charged by receiving power supply from the power supply device 20 having the above configuration.

The circuit block 30 includes a secondary battery 31, a power supply operation control circuit 32, a timepiece drive circuit 33, and a crystal resonator 34.
In the present embodiment, the secondary battery 31 is, for example, an ion lithium secondary battery. However, the present invention is not limited to this, and a rechargeable capacitor may be used for the secondary battery.
The power supply operation control circuit 32 controls the power supplied from the secondary battery 31 and outputs it to the timepiece drive circuit 33.
The timepiece driving circuit 33 includes a control circuit for controlling the operation of the timepiece, a timepiece driving oscillation circuit, a timepiece driving frequency dividing circuit, and a motor driving circuit.
The timepiece drive circuit 33 is connected to a crystal resonator 34 that constitutes a source oscillation.

  The watch movement 40 includes a conversion machine including a stepping motor including a coil block 41, a stator 42 and a rotor 43, a fifth wheel 44, a fourth wheel 45, a third wheel 46, a second wheel 47, a minute wheel 48 and A wheel train including the hour wheel 49. In the stepping motor, when a current is passed through the coil block 41, a magnetic field is generated, and the rotor 43 is rotated stepwise by 180 degrees. The operation of the stepping motor is controlled by a control signal output from the control circuit of the timepiece driving circuit 33. The fifth wheel 44 is rotated by the stepping motor, and the fourth wheel 45 is rotated by the fifth wheel 44. A second hand 15 is attached to the fourth wheel 45 via a second hand shaft.

  The third wheel 46 is rotated by the fourth wheel 45, the second wheel 47 is rotated by the third wheel 46, the minute wheel 48 is rotated by the second wheel 47, and the hour wheel 49 is the minute wheel. Rotate by 48. The minute hand 16 is attached to the center wheel 47 via a minute hand shaft, and the hour hand 17 is attached to the hour wheel 49 via an hour hand shaft.

  The solar panel 11 having the above-described configuration is shielded by, for example, the time hand 14, but hereinafter, a specific cell detection process for detecting a cell having the largest light shielding area among the four cells 11A to 11D will be described with reference to FIG. The description will be given with reference.

FIG. 5 is a flowchart showing specific cell detection processing in the present embodiment.
In the present embodiment, as shown in FIG. 4, only the cell 11C is shielded by 20% by the time pointer 14, and the remaining cells 11A, 11B, and 11D are not shielded at all.

  First, in step S51, the charging control circuit 23 closes only the switch SWA among the switches SWA, SWB, SWC, and SWD. Then, in the solar panel 11, only the cell 11A is short-circuited among the four cells 11A, 11B, 11C, and 11D, and the cell 11A does not function. For this reason, the solar panel 11 includes only the remaining three cells 11B, 11C, and 11D. As a result, the output current of the solar panel 11 is adjusted to the cell 11C (20% light shielding) having the largest light shielding area among the three cells 11B, 11C, and 11D. That is, the output current value It of the solar panel 11 can be expressed by the following formula (1).

  It = 0.8I (1)

Here, in Expression (1), I is the output current value of the solar panel 11 when all the four cells 11A to 11D are not shielded from light, and 0.8I means the output of the solar panel 11 It shows that the current is adjusted to the cell 11C (20% light shielding) having the largest light shielding area.
Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 is

    Vt = 0.8IR (2)

It becomes. Here, R is the resistance value of the solar panel 11.

  In the next step S52, the charge control circuit 23 records the output voltage value Vt = 0.8IR measured by the voltmeter 22 in, for example, the RAM of the charge control circuit 23.

  In subsequent step S53, the charging control circuit 23 opens the switch SWA closed in step S51, and closes only the switch SWB among the switches SWA, SWB, SWC, and SWD. Then, in the solar panel 11, only the cell 11B is short-circuited among the four cells 11A, 11B, 11C, and 11D, and the cell 11B does not function. For this reason, the solar panel 11 is comprised only with the remaining three cells 11A, 11C, and 11D.

  As a result, the output current of the solar panel 11 is adjusted to the cell 11C (20% light shielding) having the largest light shielding area among the three cells 11A, 11C, and 11D. That is, the output current value It of the solar panel 11 can be expressed in the same manner as the above-described formula (1). Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 can also be expressed by the above-described equation (2).

  In the next step S54, the charge control circuit 23 records the output voltage value Vt = 0.8IR measured by the voltmeter 22 in, for example, the RAM of the charge control circuit 23.

  In subsequent step S55, the charging control circuit 23 opens the switch SWB closed in step S53, and closes only the switch SWC among the switches SWA, SWB, SWC, and SWD. Then, in the solar panel 11, only the cell 11C which is short-circuited and shielded from the four cells 11A, 11B, 11C, and 11D does not function. For this reason, the solar panel 11 is comprised only with the remaining three cells 11A, 11B, and 11D. Since these three cells 11A, 11B, and 11D are all cells that are not shielded from light, the output current value It of the solar panel 11 can be expressed by the following equation (3).

  It = I (3)

  Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 is

  Vt = IR (4)

It becomes.

  In the next step S56, the charge control circuit 23 records the output voltage Vt = IR measured by the voltmeter 22 in, for example, the RAM of the charge control circuit 23.

  In subsequent step S57, the charging control circuit 23 opens the switch SWC closed in step S55, and closes only the switch SWD among the switches SWA, SWB, SWC, and SWD. Then, in the solar panel 11, only the cell 11D is short-circuited among the four cells 11A, 11B, 11C, and 11D, and the cell 11D does not function. For this reason, the solar panel 11 is comprised only by the remaining three cells 11A, 11B, and 11C.

  As a result, the output current of the solar panel 11 is adjusted to the cell 11C (20% light shielding) having the largest light shielding area among the three cells 11A, 11B, and 11C. That is, the output current value It of the solar panel 11 can be expressed in the same manner as the above-described formula (1). Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 can also be expressed by the above-described equation (2).

  In the next step S58, the charge control circuit 23 records the output voltage value Vt = 0.8IR measured by the voltmeter 22 in, for example, the RAM of the charge control circuit 23.

  The output voltage value Vt detected when the cells 11A to 11D are short-circuited as described above is as shown in FIG. In subsequent step S59, the charging control circuit 23 compares the detected output voltage values Vt to detect a cell having the maximum output voltage value Vt. In this example, as shown in FIG. 6, the output voltage value Vt becomes maximum when the cell 11C is closed by the switch SWC, and the output voltage value Vt = IR. For this reason, the charge control circuit 23 detects that the cell 11C is the cell having the largest light-shielding area (hereinafter also referred to as a specific cell) among the four cells 11A, 11B, 11C, and 11D.

  In step S60, the charging control circuit 23 opens the switch SWD closed in step S57, and holds the switch SWC of the cell 11C detected as the specific cell having the largest light shielding area in the closed state. Exit.

  By such a process, the solar panel 11 is configured by the remaining cells 11A, 11B, and 11D without using the cell 11C having the largest light shielding area among the plurality of cells 11A to 11D. The closed state of the switch SWC is held until the next specific cell detection process is executed.

Next, the execution timing of the specific cell detection process described above will be described.
In the present embodiment, in order to increase the detection accuracy of the specific cell, the execution timing of the specific cell detection process is adjusted to the rotation of the second hand 15, which moves most frequently among the second hand 15, the minute hand 16, and the hour hand 17. That is, when the solar panel 11 is composed of four cells 11A, 11B, 11C, and 11D as shown in FIG. 2, one round of the second hand 15 is 60 seconds, so the interval is 15 seconds divided by the number of cells 4. The specific cell detection process is executed.

  Note that the specific cell detection process may be executed even at intervals of 5 seconds, 3 seconds, and 1 second obtained by further dividing 15 seconds by 3, 5, and 15. In this case, since the power consumption increases, it is desirable to determine the execution timing of the specific cell detection process in consideration of the balance effect between the detection accuracy of the specific cell and the power consumption.

  As described above, according to the present embodiment, the power supply device 20 includes the plurality of cells 11A to 11D connected in series, the switches SWA to SWD connected in parallel to the plurality of cells 11A to 11D, and the voltage A total 22 and a charge control circuit 23 are provided. The cells 11A to 11D receive light and convert it into electric power. The voltmeter 22 measures the voltages of the plurality of cells 11A to 11D. Then, the charging control circuit 23 sequentially opens and closes the switches SWA to SWD, and detects a cell having the largest light shielding area based on the voltage value measured by the voltmeter 22. Thereby, even when a cell is shielded by a wide hand as the watch hand 14, for example, the most shielded cell can be detected easily and accurately.

  Further, the charge control circuit 23 detects a cell (for example, the cell 11C) in which the voltage value of the plurality of cells 11A to 11D measured by the voltmeter 22 is maximum, and the cell having the maximum voltage value based on the detection result. The switch SWC connected to 11C is closed. Accordingly, the solar panel 11 can be configured by the remaining cells 11A, 11B, and 11D without using the cell 11C having the largest light shielding area among the plurality of cells 11A to 11D. Is not affected by the cell 11C having the largest light shielding area, and a stable current output characteristic can be obtained.

  Note that the charging control circuit 23 may detect a cell having the largest light-shielding area by detecting a current flowing through each of the plurality of cells 11A to 11D from the voltage value measured by the voltmeter 22. Even with such a specific cell detection processing method, the most light-shielded cell can be detected easily and accurately. Then, by closing the switch connected to the cell detected by such a specific cell detection processing method, a stable current output characteristic can be obtained as described above.

  In addition, as the execution timing of the specific cell detection process, the charging control circuit 23 detects the cell having the largest light-shielding area in the first period (for example, 15 seconds for four cells) according to the number of the plurality of cells. To do. As a result, it is possible to detect the cell having the largest light shielding area with high accuracy.

  In the electronic timepiece of the present embodiment, the control signal output from the control circuit of the timepiece drive circuit 33 on the plurality of cells 11A to 11D in the second period (the period in the case of the second hand 15 is, for example, 1 second). A plurality of cells 11 </ b> A to 11 </ b> D are divided in the driving direction of the time hand 14. Thereby, the execution timing of the specific cell detection process can be matched with the rotation of the second hand 15 that moves most frequently, and the cell having the largest light shielding area can be detected easily and with high accuracy.

  In addition, when taking the structure by which the some cell was divided | segmented into the drive direction of the time hand, in the said embodiment, although the solar panel 11 was comprised with four fan-shaped cells as shown in FIG. 2, in addition to this, for example, It may be composed of five fan-shaped cells and six fan-shaped cells. In the case where the solar panel 11 is composed of five fan-shaped cells, it is desirable to execute the specific cell detection process at intervals of 12 seconds divided by 5 since one revolution of the second hand 15 is 60 seconds. In the case where the solar panel 11 is composed of six fan-shaped cells, it is desirable to execute the specific cell detection process at intervals of 10 seconds obtained by dividing 60 seconds by 6.

  Also, an ammeter that measures the current of each of the cells 11A to 11D is provided, and the charge control circuit 23 sequentially opens and closes the switches SWA to SWD, and the light shielding area is based on the current value measured by the ammeter. Even when the largest cell is detected, the light-shielded cell can be detected accurately.

[Second Embodiment]
Next, as a second embodiment, a case where two cells are shielded from light by the second hand 15, the minute hand 16, and the hour hand 17 will be described.
The configuration of the electronic timepiece in the present embodiment is the same as that described with reference to FIGS. 1, 2, and 3. However, as shown in FIG. 7, the cell 11C is shielded from light by the second hand 15 and the minute hand 16, and the hour hand 17 The difference is that the cell 11D is shielded from light. In the present embodiment, it is assumed that the cell 11C is shielded by 15% and the cell 11D is shielded by 10%. FIG. 7 is a main part circuit diagram of the power supply device of the electronic timepiece according to the second embodiment.

  The flow of the specific cell detection process in this embodiment is the same as that shown in FIG. 5, but the voltage value Vt detected by the voltmeter 22 is different. Only the parts different from the first embodiment will be described below.

  In step S51 of FIG. 5, the charging control circuit 23 closes only the switch SWA among the switches SWA, SWB, SWC, SWD. Then, the output current of the solar panel 11 is adjusted to the cell 11C (15% light shielding) having the largest light shielding area among the three cells 11B, 11C, and 11D. That is, the output current value It of the solar panel 11 can be expressed by the following formula (5).

  It = 0.85I (5)

  Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 is

  Vt = 0.85IR (6)

It becomes.

  In the next step S52, the charging control circuit 23 records the output voltage value Vt = 0.85IR measured by the voltmeter 22 in, for example, the RAM of the charging control circuit 23.

  In subsequent step S53, the charging control circuit 23 opens the switch SWA closed in step S51, and closes only the switch SWB among the switches SWA, SWB, SWC, and SWD. Then, the output current of the solar panel 11 is adjusted to the cell 11C (15% light shielding) having the largest light shielding area among the three cells 11A, 11C, and 11D. That is, the output current value It of the solar panel 11 can be expressed in the same manner as the above-described formula (5). Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 can also be expressed by the above-described equation (6).

  In the next step S54, the charge control circuit 23 records the output voltage value Vt = 0.85IR measured by the voltmeter 22 in, for example, the RAM of the charge control circuit 23.

  In subsequent step S55, the charging control circuit 23 opens the switch SWB closed in step S53, and closes only the switch SWC among the switches SWA, SWB, SWC, and SWD. Then, the output current of the solar panel 11 is adjusted to the cell 11D (10% light shielding) having the largest light shielding area among the three cells 11A, 11B, and 11D. As a result, the output current value It of the solar panel 11 can be expressed by the following formula (7).

  It = 0.9I (7)

  Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 is

  Vt = 0.9IR (8)

It becomes.

  In the next step S56, the charge control circuit 23 records the output voltage 0.9IR measured by the voltmeter 22 in, for example, the RAM of the charge control circuit 23.

  In subsequent step S57, the charging control circuit 23 opens the switch SWC closed in step S55, and closes only the switch SWD among the switches SWA, SWB, SWC, and SWD. Then, the output current of the solar panel 11 is adjusted to the cell 11C (15% light shielding) having the largest light shielding area among the three cells 11A, 11B, and 11C. That is, the output current value It of the solar panel 11 can be expressed in the same manner as the above-described formula (5). Therefore, the output voltage value Vt of the solar panel 11 measured by the voltmeter 22 can also be expressed by the above-described equation (6).

  In the next step S58, the charge control circuit 23 records the output voltage value Vt = 0.85IR measured by the voltmeter 22 in, for example, the RAM of the charge control circuit 23.

  The output voltage value Vt at the time of short circuit of each cell 11A-11D detected as mentioned above becomes as shown in FIG. In subsequent step S59, the charging control circuit 23 compares the detected output voltage values Vt to detect a cell having the maximum output voltage value Vt. In this example, as shown in FIG. 8, the output voltage value Vt becomes maximum when the cell 11C is closed by the switch SWC, and the output voltage value Vt = 0.9IR. For this reason, the charge control circuit 23 detects that the cell 11C is the cell having the largest light-shielding area among the four cells 11A to 11D.

  In step S60, the charging control circuit 23 opens the switch SWD closed in step S57, holds the switch SWC of the cell 11C detected as the specific cell in a closed state, and ends this process.

By such a process, the solar panel 11 is constituted by the remaining cells 11A, 11B, and 11D without using the cell 11C having the largest light shielding area among the plurality of cells 11A to 11D.
This embodiment also has the same effect as the first embodiment.

[Third Embodiment]
In 3rd Embodiment, the example from which the shape and arrangement | positioning of the several cell which comprise a solar panel differ from the said 1st and 2nd embodiment is shown.
FIG. 9 is a plan view showing a configuration example of the solar panel 71 of the electronic timepiece according to the third embodiment of the present invention. FIG. 10 is a main part circuit diagram of the power supply device of the electronic timepiece according to the third embodiment.

  As shown in FIG. 9, the solar panel 71 has a substantially circular shape in plan view, and is composed of cells 71A, 71B, 71C, 71D divided into four in the lateral direction. As shown in FIG. 10, the switch unit 21 includes switches SWA, SWB, SWC, and SWD connected in parallel to the four cells 71A to 71D. The voltmeter 22 is connected in series to the cells 71 </ b> A to 71 </ b> D and measures the cell voltage.

As shown in FIG. 10, the switch unit 21 includes switches SWA, SWB, SWC, and SWD connected in parallel to the four cells 71A to 71D. The voltmeter 22 is connected in series to the cells 71 </ b> A to 71 </ b> D and measures the cell voltage.
The charge control circuit 23 outputs the control signal D1 to open and close the switches SWA to SWD in sequence, and based on the voltage value measured by the voltmeter 22, the cell having the largest light-shielding area among the cells 71A to 71D. It is a control part to detect.

Other configurations of the electronic timepiece in the present embodiment are the same as those described in FIGS. 1 and 3 in the first embodiment, and the specific cell detection process in the present embodiment is also the same as that in the first embodiment. This is the same as that described in FIG.
Even with such a configuration, the same effects as those of the first embodiment can be obtained.

  The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention. For example, in each of the above embodiments, when measuring the voltage of the solar panel, the switching order of the switches SWA, SWB, SWC, and SWD is switched in order corresponding to the driving direction of the time hand 14, but is random. You may switch to.

  Note that all or a part of the functions of FIG. 3 of the present embodiment can be executed by a program stored in a ROM or the like connected to a CPU (not shown).

11 Solar panel 11A, 11B, 11C, 11D Cell 14 Time pointer 20 Power supply device 22 Voltmeter 23 Charge control circuit (control unit)
SWA, SWB, SWC, SWD switch

Claims (9)

A plurality of serially connected cells that receive light and convert it into electrical power;
A switch connected in parallel to each of the plurality of cells;
A voltmeter for measuring a voltage of the plurality of cells connected in series;
A controller that sequentially opens and closes the switch and detects a cell having the largest light-shielding area based on a voltage value measured by the voltmeter;
A power supply apparatus comprising: The controller is
The power supply apparatus according to claim 1, wherein a cell having the largest light-shielding area is detected by detecting a current flowing through each of the plurality of cells from a voltage value measured by the voltmeter. The controller is
The power supply apparatus according to claim 1, wherein a switch connected in parallel to the cell having the largest light-shielding area is closed. The controller is
The power supply device according to any one of claims 1 to 3, wherein a switch that has been closed is closed when a voltage value measured by the voltmeter becomes maximum. The controller is
The power supply device according to any one of claims 1 to 4, wherein the cell having the largest light-shielding area is detected in a first period corresponding to the number of the plurality of cells. Comprising a pointer driven on the plurality of cells in accordance with a control signal of the control unit in a second period;
The plurality of cells are:
The power supply device according to any one of claims 1 to 5, wherein the power supply device is divided in a driving direction of the pointer. An ammeter for measuring the current of each of the plurality of cells;
The controller is
7. The cell according to claim 1, wherein the switch is sequentially opened and closed, and the cell having the largest light-shielding area is detected based on a current value measured by the ammeter. Power supply. A plurality of serially connected cells that receive light and convert it into electrical power;
A switch connected in parallel to each of the plurality of cells;
A voltmeter for measuring a voltage of the plurality of cells connected in series;
A controller that sequentially opens and closes the switch and detects a cell having the largest light-shielding area based on a voltage value measured by the voltmeter;
An electronic timepiece characterized by comprising: The controller is
By detecting the current flowing through each of the plurality of cells from the voltage value measured by the voltmeter,
The electronic timepiece according to claim 8, wherein a cell having the largest light shielding area is detected.

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