JP2013048528A - Illumination power control method and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination power control method and a lighting device that can perform efficient charging of a secondary battery while avoiding a decline in illumination intensity in a surrounding area in the case that charging the secondary battery and illuminating the surrounding area is performed by electric power generated by a solar cell.SOLUTION: Regarding a time period from clock time t4 to clock time t5 common to a time period from the clock time t4 to the clock time t5 when generation voltage of a solar panel exceeds a prescribed voltage threshold and a time period from clock time t3 to clock time t6 when charging current of a secondary battery exceeds a prescribed current threshold, if an LED is on in a high or low intensity state, driving current of the LED is limited and the current corresponding to it is diverted to charging the secondary battery.

Description

  The present invention performs a lighting power control method for controlling power supplied to a light source driven by power generated by a solar panel and / or power discharged by a secondary battery charged with the power, and this control method is executed. The present invention relates to a lighting device.

  In recent years, the energy density of secondary batteries and the number of cycles that can be charged and discharged have increased, and coupled with the progress of improvements in various characteristics, the places where secondary batteries are used have become widespread. Rechargeable batteries can be recharged and reused without being discarded even after the discharge is completed, so solar cells that use natural energy (solar panels), especially when resource saving and reduction of running costs are important A synergistic effect is expected when used together.

  For example, Patent Documents 1 and 2 disclose an illuminating device including a solar battery that charges a built-in secondary battery and an LED that is lit by the charged secondary battery. This type of lighting device charges the secondary battery exclusively by the power from the solar battery during the day, and illuminates by the power from the secondary battery at night (or when the ambient illuminance decreases) It is not possible to supply power to the LED while charging the secondary battery with the power from the battery. In the lighting devices disclosed in Patent Documents 1 and 2, when a secondary battery is fully charged except when a secondary battery having excellent overcharge resistance characteristics such as a nickel cadmium battery is used, the battery is overcharged. Charging is stopped to prevent this.

  On the other hand, for example, in an illumination device that is also used as auxiliary light during the day, the secondary battery is charged with power from the solar battery during the day and is also illuminated, and is illuminated exclusively with power from the secondary battery at night. It becomes. Thus, in an apparatus that can simultaneously charge a secondary battery with power from the solar battery and supply power to a light source that illuminates the surroundings, the solar battery, the secondary battery, and the light source are connected via a switch. Connected in parallel.

JP 2004-259521 A JP 2010-55789 A

  However, when lighting is performed while the secondary battery is being charged, a considerable proportion of the power generated by the solar battery is supplied to the light source. There was a problem that the secondary battery could not be charged efficiently.

  The present invention has been made in view of such circumstances, and an object of the present invention is to avoid a decrease in ambient illuminance when the secondary battery is charged and the surrounding illumination is performed using the power generated by the solar battery. Another object of the present invention is to provide a lighting power control method and a lighting device capable of efficiently charging a secondary battery.

  The illumination power control method according to the present invention is driven by a secondary battery that is charged with power generated by a solar panel, and power supplied by the secondary battery and / or supply of power generated by the solar panel. In a method of controlling power supplied to the light source by a lighting device comprising a light source, the power generation voltage or output current of the solar panel and the charging current of the secondary battery are detected, and the generated power generation voltage or output current is detected. The electric power supplied to the light source is limited based on one or both of the charging current and the charging current.

  The method for controlling illumination power according to the present invention is characterized in that when the detected power generation voltage or output current is larger than a predetermined magnitude and a charging current is detected, the power supplied to the light source is limited. To do.

  The method for controlling illumination power according to the present invention includes a PWM control unit that PWM-controls the power generated by the solar panel and supplies the power to the secondary battery and the light source, and detects the battery voltage of the secondary battery, The PWM control is performed by determining the duty ratio based on the detected difference between the generated voltage and the battery voltage.

  In the illumination power control method according to the present invention, a switch is interposed in a power supply path from the solar panel to the secondary battery and the light source, and the secondary battery is fully charged based on the detected charging current. Whether or not the battery is in a state is detected, and when it is detected that the battery is fully charged, the switch is turned off.

  A lighting device according to the present invention includes a secondary battery that is charged with power generated by a solar panel, and a light source that is driven by supply of power discharged from the secondary battery and / or power generated by the solar panel. The lighting device includes a power generation detection unit that detects a power generation voltage or output current of the solar panel, and a current detection unit that detects a charging current of the secondary battery, and the power generation voltage or output detected by the power generation detection unit. The power supplied to the light source is limited based on one or both of the current and the charging current detected by the current detection unit.

  The lighting device according to the present invention provides power supplied to the light source when the power generation voltage or output current detected by the power generation detection unit is larger than a predetermined value and the current detection unit detects a charging current. It is characterized by restricting.

  The illumination device according to the present invention includes a PWM control unit that PWM-controls the power generated by the solar panel and supplies the power to the secondary battery and the light source, and a voltage detection unit that detects a battery voltage of the secondary battery. The PWM control unit is configured to perform PWM control by determining a duty ratio based on a difference between a power generation voltage detected by the power generation detection unit and a battery voltage detected by the voltage detection unit. .

  The lighting device according to the present invention includes a switch in a power supply path from the solar panel to the secondary battery and the light source, and the secondary battery is based on the charging current detected by the current detection unit. Detection means for detecting whether or not the battery is fully charged is provided, and when the detection means detects that the battery is fully charged, the switch is turned off.

In this invention, the electric power supplied to a light source is restrict | limited based on any one or both of the electric power generation voltage or output current of a solar panel (solar cell), and the charging current of a secondary battery.
Here, when the power generation voltage or output current of the solar panel is appropriately detected, it is assumed that the surroundings are appropriately illuminated by sunlight, and the charge / discharge current of the secondary battery is swung to the charging side. In this case, it is assumed that sunlight is incident at such an illuminance that the surplus power generated by the solar panel is directed to charging. In any of the above cases or a combination of these, even if the illuminance of the light source is reduced in a room where sunlight enters, the user's convenience is unlikely to be impaired, so the power supplied to the light source is limited. As a result, the electric power directed to the charging of the secondary battery is increased, and the influence of the decrease in the amount of ambient light due to insufficient illumination is suppressed to a small level. And long-time illumination at night is possible.
Note that, depending on the mounting form of the lighting device, if the light source is not turned on during power generation of the solar battery, the light is not turned on even when the switch is turned on, and the user may consider it a failure. To prevent this, it is necessary to turn on the light source during daytime solar cell power generation even when the surroundings are so bright that the light source does not need to be turned on.

In the present invention, when the generated voltage or output current of the solar panel is larger than a predetermined value and the charging current of the secondary battery is detected, the power supplied to the light source is limited.
As a result, when the power generation voltage of the solar panel is higher than a certain voltage or when the output current from the solar panel is larger than the certain current, and at least a part of the output current from the solar panel is When it is directed to charge the secondary battery, it is assumed that the surroundings are brightly illuminated by sunlight. Therefore, the power supplied to the light source is limited and directed to charge the secondary battery.

In the present invention, when the electric power generated by the solar panel is PWM-controlled and supplied to the secondary battery and the light source, the PWM control is performed based on the difference between the generated voltage generated by the solar panel and the battery voltage of the secondary battery. Determine the duty ratio.
Thus, when the duty ratio is controlled to be small / large according to the large / small difference between the generated voltage and the battery voltage, the secondary battery is prevented from being overcharged. Further, in the power supply path to the secondary battery and the light source, for example, heat generation in a constant current circuit or a dropper circuit can be suppressed.

  In the present invention, in order to prevent the secondary battery from being overcharged when the secondary battery charged by the power generated by the solar panel is fully charged, the secondary battery is removed from the solar panel. In addition, the power supplied to the light source is cut off.

According to the present invention, when the power generation voltage of the solar panel (solar cell) is high or the output current is large, or when the charging / discharging current of the secondary battery is swung to the charging side, this corresponds to one or both. In this case, by limiting the power supplied to the light source, the power directed to the charging of the secondary battery increases, and the influence of a decrease in the amount of ambient light due to insufficient illumination can be suppressed to a small level.
Therefore, when the secondary battery is charged and the surrounding illumination is performed using the electric power generated by the solar battery, it is possible to efficiently charge the secondary battery while avoiding a decrease in ambient illuminance.

1 is a perspective view schematically showing an appearance of a lighting device according to the present invention. It is a circuit diagram which briefly shows the connection structure of an illuminating device. A is an explanatory diagram showing the time change of the power generation voltage of the solar panel, B is an explanatory diagram showing the time change of the charge / discharge current of the secondary battery, C is an explanatory diagram showing a period during the power generation by the solar panel, D is the LED It is explanatory drawing which shows the period which restrict | limits a drive current. It is a flowchart which shows the process sequence of CPU which carries out PWM control of the electric current output from a constant current circuit. It is a flowchart which shows the process sequence of CPU which calculates the residual amount of a secondary battery. It is a flowchart which shows the process sequence of CPU which monitors the discharge end state of a secondary battery. It is a flowchart which shows the process sequence of CPU which restrict | limits the drive current of LED.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a perspective view schematically showing the appearance of a lighting device according to the present invention. In the figure, reference numeral 1 denotes a case made of a synthetic resin. The case 1 has a substantially rectangular shape when viewed from the front, and an L shape when viewed from the side. On the front of the case 1, a solar panel 2 composed of eight solar cells 21, 22,... 28 is arranged so as to form a grid pattern of a grid. On the back surface of the case 1, LEDs 82 and 86 (see FIG. 2) that illuminate the surroundings are provided side by side in the center in the height direction, and a push switch 961 (for switching on and off of the LEDs 82 and 86) 2) is provided at the top of one side.

  The electric power generated by the solar panel 2 is charged in a secondary battery 6 described later, and the LEDs 82 and 86 emit light by the electric power discharged from the secondary battery 6 and / or the electric power generated by the solar panel 2, so that the surroundings are Illuminated. The light emission intensities of the LEDs 82 and 86 can be switched by the push switch 961 so that each time the push switch 961 is pressed, the LEDs 82 and 86 are cyclically switched to “light”, “light”, and “light off”. It has become.

  FIG. 2 is a circuit diagram schematically showing the connection configuration of the illumination device. In FIG. 2, a resistor and a capacitor for appropriately reducing noise in the main part of the circuit are omitted without being shown. The illustration and description of the pull-up resistors that are used as appropriate are also omitted. All of the MOSFETs shown in the figure are P-channel type, and all of the grounded transistors are NPN type. The resistor connected between the base of each NPN transistor and the ground potential is for surely turning on and off each transistor, and the description thereof is omitted.

The lighting device includes a solar panel 2 formed by connecting solar cells 21, 22,... 28 in series. The voltage generated by the solar panel 2 is applied to the base of the base-grounded transistor 32 via the resistor 31, and the input terminal of the constant current circuit 4 and one end to the ground potential via the backflow prevention diode 33. It is given to the other end of the series circuit of the connected resistors 34 and 35.
Note that the circuit shown in FIG. 2 does not include a circuit for detecting the current generated by the solar panel 2, but in order to use it as an index of the power generated by the solar panel 2, for example, a current flowing in the diode 33 in the forward direction is used. You may make it detect.

  The constant current circuit 4 includes a resistor 41 having one end connected to an input terminal, and a PNP transistor 42 having a collector connected to an output terminal, and a control terminal 40 is connected to the base of the transistor 42. . The emitter of the transistor 42 is connected to the other end of the resistor 41. The emitter and base of a PNP transistor 43 are connected to both ends of the resistor 41 so that the voltage drop generated in the resistor 41 is in the forward direction. The collector of the transistor 43 is connected to the base of the transistor 42 via a forward diode 44.

  The control terminal 40 of the constant current circuit 4 is connected to the collector of the grounded transistor 46 through a resistor 45. The output terminal of the constant current circuit 4 is connected to the source of the charging MOSFET 50 and one end of the resistor 51 through the resistor 48. The other end of the resistor 51 is connected to the gate of the MOSFET 50 and the other end of the resistor 52 whose one end is connected to the collector of the transistor 53 whose base is grounded.

  The drain of the MOSFET 50 for charging is a series circuit of a positive terminal of the secondary battery 6 formed by connecting the cells 61 and 62 made of nickel metal hydride batteries in series and the resistors 64 and 65 having one end connected to the ground potential. Is connected to the other end. The negative terminal of the secondary battery 6 is connected to the ground potential via the resistor 63. The connection point of the cells 61 and 62 is connected to the other end of a series circuit of resistors 66 and 67 having one end connected to the ground potential.

  The drain of the charging MOSFET 50 and the positive terminal of the secondary battery 6 are connected to the source of the discharging MOSFET 55 and one end of the resistor 55. The other end of the resistor 55 is connected to the gate of the MOSFET 55 and to the other end of the resistor 57 whose one end is connected to the collector of the grounded transistor 58. The drain of the discharging MOSFET 55 is connected to the input terminal of the switching power supply unit 7.

  The switching power supply unit 7 outputs Vcc (+5 V), and the output terminal is connected to the anodes of the LEDs 82 and 86 via the resistors 81 and 85, respectively. The cathodes of the LEDs 82 and 86 are connected to the collectors of the base-grounded transistors 83 and 87, respectively.

  The lighting device also includes a control unit 9 composed of a microcomputer. The control unit 9 includes a CPU 91. The CPU 91 includes a ROM 92 that stores information such as programs, a RAM 93 that stores temporarily generated information, a timer 94 that measures various times in parallel, and each unit in the lighting device. A bus is connected to an I / O port 96 for input / output. The input terminal of the I / O port 96 is connected to the collector of the transistor 32 and the other end of the push switch 961 having one end connected to the ground potential. The output terminal of the I / O port 96 is connected to the bases of the transistors 53 and 58 via resistors 54 and 59, respectively.

  The CPU 91 is also connected by bus to an A / D conversion circuit 97 that converts an analog voltage into a digital voltage, and PWM control circuits 95 and 98 that arbitrarily control the duty ratio of an output control signal. . The A / D conversion circuit 97 is connected to the connection points of the resistors 34 and 35, the connection points of the resistors 64 and 65, the connection points of the resistors 66 and 67, and both ends of the resistor 63. The PWM control circuit 95 is connected to the base of the transistor 46 through the resistor 47. The PWM control circuit 98 is connected to the bases of the transistors 83 and 87 via resistors 84 and 88, respectively.

  The ROM 92 is a nonvolatile memory composed of an EEPROM (Electrically Erasable Programmable ROM) or a flash memory. In addition to the program, the ROM 92 stores fixed data such as an initial value of the remaining amount of the secondary battery 6. The CPU 91 executes various processes for realizing the function as the illumination device according to the present invention in accordance with a control program stored in advance in the ROM 92. In the following, the operation of the circuit of FIG. 2 and the outline of the processing contents of the CPU 91 will be described.

  When sunlight is irradiated and the solar panel 2 starts power generation, a base current flows to the transistor 32 via the resistor 31, the transistor 32 is turned on, and the collector becomes L (low) level. The CPU 91 detects that the solar panel 2 is generating power by taking in the L level of the collector of the transistor 32 via the I / O port 96.

  The voltage generated by the solar panel 2 is divided by a series circuit of resistors 34 and 35, and the divided voltage is taken into the A / D conversion circuit 97 and converted into a digital voltage value. The CPU 91 takes in the converted digital voltage value and reversely calculates the voltage division ratio by the resistors 34 and 35 to detect the power generation voltage of the solar panel 2.

  The constant current circuit 4 is a circuit that makes the collector current of the transistor 42 flowing between the input terminal and the output terminal constant. When the voltage drop generated in the resistor 41 due to the collector current of the transistor 42 flowing through the resistor 41 rises to the ON voltage between the emitter and base of the transistor 43, the transistor 43 starts to conduct. After that, the voltage obtained by adding the emitter-collector voltage of the transistor 43 and the on-voltage of the diode 44 is equal to the voltage obtained by adding the emitter-base voltage of the transistor 43 and the emitter-base voltage of the transistor 42. The collector currents of the transistors 42 and 43 are balanced. In this state, the voltage drop generated in the resistor 41 is substantially equal to the on-voltage between the emitter and base of the transistor 43, so that the collector current of the transistor 42 is kept constant (250 mA in this embodiment).

  By the way, in order to allow the collector current to flow through the transistor 42, it is necessary to cause the base current of the transistor 42 to flow to the ground potential via the control terminal 40, the resistor 45, and the transistor 46. Here, the transistor 46 is turned on when the control signal supplied from the PWM control circuit 95 to the base of the transistor 46 via the resistor 47 is turned on. Therefore, a constant current flows between the input terminal and the output terminal of the constant current circuit 4 with a duty ratio corresponding to the control signal output from the CPU 91 to the PWM control circuit 95. That is, the constant current flowing through the constant current circuit 4 is reduced at a duty ratio corresponding to the control signal. The CPU 91 controls the duty ratio of the control signal to be small / large according to the large / small difference between the voltage generated by the solar panel 2 and the battery voltage of the secondary battery 6. Thereby, the overcharge of the secondary battery 6 is prevented. Further, in the power supply path to the secondary battery and the light source, for example, heat generation in a constant current circuit or a dropper circuit can be suppressed.

  In the MOSFET 50 for charging, when the transistor 53 to which an ON signal is applied to the base from the output terminal of the I / O port 96 via the resistor 54 is turned on, the gate becomes L level, and the source and the drain become conductive. In this way, the MOSFET 50 is normally turned on, and among the current supplied from the constant current circuit 4 via the resistor 48 while the solar panel 2 is generating power, the current consumed for lighting the LEDs 82 and 86. The secondary battery 6 is charged by the surplus current excluding.

  The voltage across the secondary battery 6 is divided by a series circuit of resistors 64 and 65. The divided voltage is taken into the A / D conversion circuit 97 and converted into a digital voltage value. Similarly, in the secondary battery 6, the voltage across the cell 62 on the ground potential side is divided by the series circuit of the resistors 66 and 67, and the divided voltage is supplied to the A / D conversion circuit 97. Captured and converted to a digital voltage value. The CPU 91 takes in these converted voltage values and reversely calculates the voltage division ratios of the resistors 64 and 65 and the resistors 66 and 67 to detect the battery voltages of the secondary battery 6 and the single battery 62. The battery voltage of the single battery 61 is calculated by subtracting the battery voltage of the single battery 62 from the battery voltage of the secondary battery 6.

  The voltage drop generated in the resistor 63 by the charge / discharge current of the secondary battery 6 (the charge current is a positive current and the discharge current is a negative current) is taken into the A / D conversion circuit 97 and is digitally converted. Converted to current value. The CPU 91 detects the charge / discharge current of the secondary battery 6 by taking in the converted digital current value. The CPU 91 detects the charging / discharging current of the secondary battery 6 at a cycle of 250 ms, calculates an average value for 1 minute, integrates the calculated charging / discharging current, and calculates the remaining amount of the secondary battery 6.

  When the calculated remaining amount is 2000 mAh or more, the CPU 91 turns off the ON signal supplied from the output terminal of the I / O port 96 to the base of the transistor 53 via the resistor 54, thereby charging the MOSFET 50 for charging. Is turned off to stop the charging of the secondary battery 6. When the battery voltage of the single battery 61 or 62 becomes 1.45 V or more while calculating the remaining amount, the CPU 91 forcibly corrects the remaining amount of the secondary battery 6 to 1500 mAh (= 75%). Further, when the battery voltage of the single battery 61 or 62 becomes less than 1.15 V during calculation of the remaining amount, the CPU 91 forcibly corrects the remaining amount of the secondary battery 6 to 100 mAh (= 5%).

  In the discharging MOSFET 55, when the transistor 58 to which an ON signal is applied to the base from the output terminal of the I / O port 96 via the resistor 59 is turned on, the gate becomes L level, and the source and the drain become conductive. The MOSFET 55 in the ON state in this way is a current supplied from the constant current circuit 4 via the charging MOSFET 50 while the solar panel 2 is generating power and / or a current discharged from the secondary battery 6. Is conducted to the input terminal of the switching power supply unit 7.

  When the battery voltage of the secondary battery 6 detected at a cycle of 250 ms is continuously less than 2V (e.g., less than 1V / cells 61, 62) during the discharge of the secondary battery 6 (for example, 8 times). In order to prevent the secondary battery 6 from being over-discharged, the CPU 91 turns off the ON signal supplied from the output terminal of the I / O port 96 to the base of the transistor 58 via the resistor 59. The MOSFET 55 is turned off. In this case, the CPU 91 further corrects the remaining amount of the secondary battery 6 to 0 mAh and forcibly turns off the LEDs 82 and 86.

  When the transistors 83 and 87 are turned on, the LEDs 82 and 86 are driven by a current flowing from the Vcc (+5 V) through the resistors 81 and 85 to emit light. The transistors 83 and 87 are turned on when the control signal supplied from the PWM control circuit 98 to the bases of the transistors 83 and 87 via the resistors 84 and 88 is turned on. Therefore, the LEDs 82 and 86 are PWM dimmed at a duty ratio corresponding to the control signal output from the CPU 91 to the PWM control circuit 98. Since the current and power supplied to the LEDs 82 and 86 are constant while the transistors 83 and 87 are on, PWM control of the current that drives the LEDs 82 and 86 means that the power supplied to the LEDs 82 and 86 is PWM. Control and consent.

The specific example which restrict | limits the electric power supplied to LED82,86 based on the electric power generation voltage of the solar panel 2 and the charging / discharging electric current of the secondary battery 6 with the illuminating device comprised as mentioned above is demonstrated.
3A is an explanatory diagram showing the time change of the power generation voltage of the solar panel 2, B is an explanatory diagram showing the time change of the charge / discharge current of the secondary battery 6, and C is an explanation showing the period during power generation by the solar panel 2. FIG. FIG. 4D is an explanatory diagram showing a period during which the drive current of the LEDs 82 and 86 is limited. In the figure, the horizontal axis represents time, and the vertical axis from A to D represents the generated voltage, the charge / discharge current, the detection signal during power generation, and the LED drive current.

In FIG. 3A to FIG. 3D, the amount of sunlight irradiated to the solar panel 2 increases from before the time t1 until the time t4 passes, and the amount of light changes from increasing to decreasing during the period from the time t4 to the time t5. Thereafter, the amount of light continues to decrease until after time t8.
From time t1 to time t8, the transistor 32 continues to be turned on, thereby detecting that the solar panel 2 is generating power. At time t1, the electric power generated by the solar panel 2 does not contribute to the charging of the secondary battery 6, and the secondary battery 6 is discharged to drive the LEDs 82 and 86.

  The electric power generated by the solar panel 2 starts to contribute to the charging of the secondary battery 6 from the time t1 to the time t2, and the LEDs 82 and 86 are turned on by the electric power generated by the solar panel 2 from the time t2 to the time t7. The power to be driven is covered and the secondary battery 6 is charged with surplus power.

  Between time t3 and time t6, the charge / discharge current of the secondary battery 6 exceeds a predetermined current threshold. Between time t4 and time t5 when the amount of sunlight further increases, the power generation voltage of the solar panel 2 exceeds a predetermined voltage threshold. In the present embodiment, a period in which the charge / discharge current of the secondary battery 6 exceeds a predetermined current threshold and the generated voltage of the solar panel 2 exceeds the predetermined voltage threshold, that is, from time t4 to time t5. In the meantime, the drive currents of the LEDs 82 and 86 are limited assuming that the surroundings are brightly illuminated by sunlight.

Below, operation | movement of the control part 9 of the illuminating device mentioned above is demonstrated using the flowchart which shows it. The following processing is executed by the CPU 91 in accordance with a control program stored in advance in the ROM 92.
FIG. 4 is a flowchart showing a processing procedure of the CPU 91 that performs PWM control on the current output from the constant current circuit 4, and FIG. 5 is a flowchart showing a processing procedure of the CPU 91 that calculates the remaining amount of the secondary battery 6. FIG. 6 is a flowchart showing a processing procedure of the CPU 91 that monitors the discharge end state of the secondary battery 6. FIG. 7 is a flowchart showing the processing procedure of the CPU 91 for limiting the drive current of the LEDs 82 and 86.

The process of FIG. 4 is started at a cycle of 250 ms while the power generation detection signal (see FIG. 3C) is on by turning on the transistor 32 by the voltage generated by the solar panel 2, but is limited to this. It is not something.
When the process of FIG. 4 is started, the CPU 91 detects the generated voltage of the solar panel 2 via the series circuit of the resistors 34 and 35 and the A / D conversion circuit 97 (S11), and further, the resistors 64, The battery voltage of the secondary battery 6 in which the cells 61 and 62 are connected in series is detected via the 65 series circuit and the A / D conversion circuit 97 (S12).

  Next, the CPU 91 calculates the difference between the detected power generation voltage and the battery voltage (S13), and determines whether the calculated difference is greater than 6V (S14). When the voltage is higher than 6V (S14: YES), the CPU 91 sets the duty ratio set in the PWM control circuit 95 to 0% (S15) and ends the process of FIG.

  When the calculated difference is not larger than 6V (S14: NO), the CPU 91 determines whether or not the difference is smaller than 3V (S16), and when it is smaller than 3V (S16: YES), the CPU 91 sets it in the PWM control circuit 95. The duty ratio is set to 100% (S17), and the processing of FIG. On the other hand, when the difference is from 3V to 6V (S16: NO), the CPU 91 calculates the duty ratio set in the PWM control circuit 95 by [(6V−difference) /0.3V] × 10 ([x] is 4 is finished (S18), and the process of FIG. 4 is terminated. In this way, while the difference decreases from 6V to 3V, the duty ratio is controlled to increase by 10% every 0.3V.

  Next, the process of FIG. 5 is started each time the average value of the charge / discharge current of the secondary battery 6 is calculated. The charging / discharging current of the secondary battery 6 is detected at a cycle of 250 ms by another process different from the process of FIG. 5, and an average value of 240 detection values is calculated every minute. The remaining amount used in the process of FIG. 5 is stored in the RAM 93, and the battery voltage of the secondary battery 6 or the single battery 61 or the single battery 62 is detected at the time of initialization upon power-on and when the removal of the secondary battery 6 is detected. Is detected and set to an appropriate value.

  When the processing of FIG. 5 is started, the CPU 91 detects the battery voltage of the secondary battery 6 in which the single cells 61 and 62 are connected in series, and the detected battery voltage is 2 V or less which is the discharge end voltage. It is determined whether or not (S21). When it is not 2 V or less (S21: NO), the CPU 91 adds the above average value of the charge / discharge current to the remaining amount stored in the RAM 93 to update the remaining amount (S22). When the battery voltage is 2 V or less (S21: YES), the CPU 91 advances the process to step S23 without updating the remaining amount.

  Next, the CPU 91 determines whether or not the remaining amount is 2000 mAh or more (S23). If it is 2000 mAh or more (S23: YES), the CPU 91 turns off to the base of the transistor 53 via the I / O port 96 and the resistor 54. By giving a signal, the MOSFET 50 for charging is turned off (S24), and the processing of FIG. Although subsequent processing is omitted, when the remaining amount of the secondary battery 6 is reduced to 1800 mAh (corresponding to 90%), the MOSFET 50 is turned on to allow the secondary battery 6 to be charged.

  When the remaining amount is not 2000 mAh or more (S23: NO), the CPU 91 determines whether or not the secondary battery 6 is being charged (S25). Here, the determination that the battery is being charged may determine that the average value of the charge / discharge current described above is a positive current, or the power generation detected via the transistor 32 and the I / O port 96. It may be determined that the medium signal is on.

  When the secondary battery 6 is being charged (S25: YES), the CPU 91 detects the battery voltage of the single cells 61 and 62 and determines whether or not the higher battery voltage is 1.45V or more (S26). ). When it is not 1.45 or more (S26: NO), the CPU 91 ends the process of FIG. 5 without correcting the remaining amount.

  When the higher battery voltage is 1.45V or more (S26: YES), the CPU 91 determines whether or not the remaining amount stored in the RAM 93 is less than 1500 mAh (S27), and when it is not less than 1500 mAh (S27: NO), the process of FIG. 5 is terminated without correcting the remaining amount. On the other hand, when the remaining amount is less than 1500 mAh (S27: YES), the CPU 91 forcibly corrects the remaining amount to 1500 mAh (S28) and ends the processing of FIG.

  When the secondary battery 6 is not being charged in step S25 (S25: NO), that is, when the secondary battery 6 is being discharged, the CPU 91 detects the battery voltage of the single cells 61 and 62, and the lower battery voltage is detected. Is determined to be less than 1.15V (S29). If it is not less than 1.15 (S29: NO), the CPU 91 ends the process of FIG. 5 without correcting the remaining amount.

  When the lower battery voltage is less than 1.15 V (S29: YES), the CPU 91 determines whether or not the remaining amount stored in the RAM 93 is more than 100 mAh (S30), and when it is not more than 100 mAh (S30: NO). ), The process of FIG. 5 is terminated without correcting the remaining amount. On the other hand, when the remaining amount is greater than 100 mAh (S30: YES), the CPU 91 forcibly corrects the remaining amount to 100 mAh (S31) and ends the processing of FIG.

Next, the processing of FIG. 6 is started at a cycle of 250 ms, but is not limited thereto. The CNT used in this process is a variable for counting the number of times, and is stored in the RAM 93.
When the process of FIG. 6 is started, the CPU 91 detects the battery voltage of the secondary battery 6 in which the cells 61 and 62 are connected in series (S41), and whether or not the detected battery voltage is less than 2V. Is determined (S42).

  When the battery voltage is not less than 2V (S42: NO), the CPU 91 clears CNT to zero (S43) and ends the process of FIG. When the battery voltage is less than 2V (S42: YES), the CPU 91 increments CNT by 1 (S44), determines whether or not CNT has become 8 (S45), and when it has not reached 8 (S45: NO), that is, when the number of times that the battery voltage is continuously determined to be less than 2 V is less than 8, the CPU 91 ends the process of FIG. 6 as it is.

  When the CNT reaches 8 (S45: YES), that is, when it is determined that the secondary battery 6 is in a discharge end state, the CPU 91 determines the base of the transistor 58 via the I / O port 96 and the resistor 59. The discharge MOSFET 55 is turned off by giving an OFF signal to (S46). Although the subsequent processing is not shown, when the secondary battery 6 is charged by the power generated by the solar panel 2 and the push switch 961 is pressed to turn on the LEDs 82 and 86, the MOSFET 55 is turned on. The secondary battery 6 can be discharged.

  Next, the CPU 91 forcibly corrects the remaining amount stored in the RAM 93 to 0 mAh (S47), and further sets the duty ratio of the control signal applied from the PWM control circuit 98 to the transistors 83 and 87 via the resistors 84 and 88. By setting it to 0%, the LEDs 82 and 86 are turned off (S48), and the processing of FIG.

Finally, the processing of FIG. 7 is started, for example, at a cycle of 1 second, but is not limited thereto.
When the process of FIG. 7 is activated, the CPU 91 determines whether or not the LEDs 82 and 86 are lit (S51). If the LEDs are not lit (S51: NO), the LEDs 82 and 86 are not driven. Then, the processing of FIG. Whether or not the LEDs 82 and 86 are lit may be determined based on the state information stored when the push switch 961 is pressed and the LEDs 82 and 86 are lit, or set in the PWM control circuit 98. The determination may be made based on the duty ratio.

  When the LEDs 82 and 86 are lit (S51: YES), the CPU 91 determines whether or not the secondary battery 6 is in a fully charged state (S52), and in a fully charged state (S52: YES), Since there is no need to limit the drive currents of the LEDs 82 and 86 to direct the charging of the secondary battery 6, the processing of FIG. Whether or not the secondary battery 6 is in a fully charged state may be determined based on the state information stored when the charging MOSFET 50 is turned off, or the remaining amount stored in the RAM 93 is, for example, 1800 mAh (90 It may be determined on the basis of whether or not it is greater than (equivalent to%).

  When the secondary battery 6 is not in a fully charged state (S52: NO), the CPU 91 determines whether or not the secondary battery 6 is in a discharge end state. When the secondary battery 6 is in a discharge end state (S53: YES), the LED 82 , 86 are not driven, the processing of FIG. Whether or not the secondary battery 6 is in an end-of-discharge state may be determined based on the state information stored when the discharging MOSFET 55 is turned off, or may be appropriately determined based on other information. Good.

When the secondary battery 6 is not in the final discharge state (S53: NO), the CPU 91 detects that the generated voltage of the solar panel 2 detected through the series circuit of the resistors 34 and 35 and the A / D conversion circuit 97 is a threshold value. It is determined whether or not the voltage is higher than 5V (S54). The threshold voltage is not limited to 5V. If the generated voltage is not higher than 5V (S54: NO), the amount of sunlight irradiated to the solar panel 2 is not sufficient, so the CPU 91 does not limit the drive currents of the LEDs 82 and 86 in FIG. The process ends.
In step S54, instead of the determination based on the generated voltage, it is determined whether or not the output current of the solar panel 2 is larger than a predetermined current. If not, the amount of sunlight irradiated to the solar panel 2 is determined. The processing of FIG. 7 may be terminated as not being sufficient.

  When the generated voltage is higher than 5V (S54: YES), the CPU 91 detects that the charging / discharging current (the charging current here) of the secondary battery 6 detected through the resistor 63 and the A / D conversion circuit 97 is the threshold current. It is determined whether it is more than 50 mA (S55). The threshold current is not limited to 50 mA, and it may be determined whether the charging current can be detected. When the charging current is not more than 50 mA (S55: NO), the amount of sunlight irradiated to the solar panel 2 is not sufficient, so the CPU 91 does not limit the drive current of the LEDs 82 and 86 as shown in FIG. The process ends.

  When the charging current is higher than 50 mA (S55: YES), the CPU 91 determines whether or not the LEDs 82 and 86 are lit with “strong” (S56), and when the LED is lit with “strong” (S56: YES). ) After the PWM control circuit 98 switches the LEDs 82 and 86 to “low” lighting, for example, by limiting the duty ratio of the control signal applied to the transistors 83 and 87 via the resistors 84 and 88 (S57) Then, the processing of FIG. By limiting the duty ratio in this way, the electric power to be supplied to the LEDs 82 and 86 is reduced and directed to charging the secondary battery 6.

  On the other hand, when the LEDs 82 and 86 are not lit at “strong” (S56: NO), that is, when lit at “weak”, the CPU 91 causes the transistor 83 from the PWM control circuit 98 to pass through the resistors 84 and 88. , 87 by setting the duty ratio of the control signal to 0%, for example, the LEDs 82, 86 are switched off (S58), and the processing of FIG. Here, the duty ratio of the control signal may be set to a value smaller than that when the LEDs 82 and 86 are lit at “weak”, and is not limited to 0%. Even when the light emission intensity of the LEDs 82 and 86 is reduced by limiting the duty ratio in this way, it is assumed that the solar panel 2 is irradiated with a sufficient amount of sunlight. The rate of decline is kept small.

  In the present embodiment, in the process shown in FIG. 7, when the power generation voltage of the solar panel 2 is higher than the threshold voltage or the output current is larger than the predetermined current and the charging current is larger than the threshold current. The drive current of the LEDs 82 and 86 is limited according to the lighting intensity (“strong” or “weak”) of the LEDs 82 and 86, but the generated voltage is higher than the threshold voltage or the output current is larger than the predetermined current, or The drive current of the LEDs 82 and 86 may be limited when any of the cases where the charging current is larger than the threshold current.

As described above, according to the present embodiment, the current for driving the LED is limited based on one or both of the generated voltage or output current of the solar panel (solar cell) and the charging current of the secondary battery. . As a result, the current directed to the charging of the secondary battery increases, and the influence of a decrease in the amount of ambient light due to insufficient illumination can be kept small.
Therefore, when the secondary battery is charged and the surrounding illumination is performed using the electric power generated by the solar battery, it is possible to efficiently charge the secondary battery while avoiding a decrease in ambient illuminance.
For example, when a solar cell is installed outdoors and a light source is installed indoors, even if the illuminance of the light source is reduced in a room where sunlight is incident during the daytime, the user's convenience is unlikely to be impaired. If the illuminance of the light source is reduced enough to charge the battery, long-time illumination is possible at night.
Further, in the lighting device shown in FIG. 1, since the light source is installed on the back surface, it is not necessary to turn on the light source in the daytime, but even if the lighting switch is accidentally left on, Charging can be performed while limiting the power to the light source. Further, in the integrated lighting device as shown in FIG. 1, if the light source is not turned on during the power generation of the solar battery, the light is not turned on even when the switch is turned on, and there is a possibility that the user considers it as a failure. To prevent this, it is necessary to turn on the light source during daytime solar cell power generation even when the surroundings are so bright that the light source does not need to be turned on.

Moreover, when the magnitude | size of the power generation voltage or output current of a solar panel is larger than a predetermined threshold value, and the charging current of a secondary battery is detected, the electric current which drives LED is restrict | limited.
Therefore, the generated voltage of the solar panel is higher than a certain voltage or the output current from the solar panel is larger than the certain current, and at least a part of the output current from the solar panel is secondary. Even if it is directed to charging the battery, it is assumed that the surroundings are brightly illuminated by sunlight, so it is possible to limit the power supplied to the LED and redirect it to the charging of the secondary battery It becomes.

  Furthermore, when supplying current based on the power generated by the solar panel to the secondary battery and the LED by PWM control, depending on the magnitude of the difference between the generated voltage generated by the solar panel and the battery voltage of the secondary battery The duty ratio is controlled to be small / large. Therefore, it becomes possible to prevent the secondary battery from being overcharged.

  Furthermore, when the secondary battery charged by the power generated by the solar panel is fully charged, the secondary battery is overcharged by cutting off the current supplied from the solar panel to the secondary battery and the LED. Can be prevented.

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

2 Solar panel 6 Secondary battery 61, 62 Cell 82, 86 LED (light source)
34, 35 Resistor (part of power generation detector)
50 MOSFET (switch)
63 Resistor (part of current detector)
64,65 resistor (part of voltage detector)
91 CPU
92 ROM
93 RAM
95 PWM control circuit (PWM controller)
96 I / O port 97 A / D conversion circuit (part of power generation detection unit, current detection unit and voltage detection unit)

Claims (8)

Supply to the light source by a lighting device comprising: a secondary battery charged with power generated by a solar panel; and a light source driven by supply of power discharged from the secondary battery and / or power generated by the solar panel In a method of controlling power to be
Detecting the generated voltage or output current of the solar panel and the charging current of the secondary battery,
A method for controlling illumination power, comprising: limiting power supplied to the light source based on one or both of a detected generated voltage or output current and a charging current. 2. The illumination power control according to claim 1, wherein when the detected power generation voltage or output current is larger than a predetermined value and a charging current is detected, the power supplied to the light source is limited. Method. A PWM control unit that PWM-controls the power generated by the solar panel and supplies the power to the secondary battery and the light source;
Detecting the battery voltage of the secondary battery,
The method of controlling illumination power according to claim 1 or 2, wherein the duty ratio is determined based on the detected difference between the generated voltage and the battery voltage and PWM control is performed. A switch is interposed in the power supply path from the solar panel to the secondary battery and the light source,
Detecting whether or not the secondary battery is fully charged based on the detected charging current;
The method for controlling illumination power according to any one of claims 1 to 3, wherein the switch is turned off when it is detected that the battery is fully charged. In a lighting device comprising: a secondary battery charged with power generated by a solar panel; and a light source driven by supply of power discharged from the secondary battery and / or power generated by the solar panel,
A power generation detection unit for detecting the power generation voltage or output current of the solar panel;
A current detection unit for detecting a charging current of the secondary battery,
The power supplied to the light source is limited based on one or both of the generated voltage or output current detected by the power generation detection unit and the charging current detected by the current detection unit. A lighting device. When the power generation voltage or output current detected by the power generation detection unit is larger than a predetermined value and the current detection unit detects a charging current, the power supplied to the light source is limited. The lighting device according to claim 5. A PWM control unit that PWM-controls the electric power generated by the solar panel and supplies the secondary battery and the light source;
A voltage detection unit for detecting a battery voltage of the secondary battery,
The PWM control unit is configured to perform PWM control by determining a duty ratio based on a difference between a power generation voltage detected by the power generation detection unit and a battery voltage detected by the voltage detection unit. The lighting device according to 5 or 6. A switch is interposed in the power supply path from the solar panel to the secondary battery and the light source,
Detecting means for detecting whether or not the secondary battery is in a fully charged state based on the charging current detected by the current detection unit;
The lighting device according to any one of claims 5 to 7, wherein the switch is turned off when the detection means detects that the battery is fully charged.

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