JP5203672B2 - Charger - Google Patents

Description

  The present invention relates to a charging device having a power generation member.

  Portable electronic devices are added with various functions, and power consumption tends to increase. Further, in the portable electronic device, it is necessary to charge the battery using an external charging device or replace it with a new battery before the charge capacity of the battery is exhausted.

  Here, when using an external charging device, it is necessary to carry the charging device together with the portable electronic device, and the charging device requires an outlet or the like. must not.

  On the other hand, when it replaces | exchanges for a new rechargeable battery, the cost for purchasing a new rechargeable battery will start.

Therefore, a technique has been proposed in which a portable electronic device is provided with a power generation member that generates a certain amount of power separately from the rechargeable battery, and the rechargeable battery is charged by the power generation member (see, for example, Patent Document 1). ).
JP 2004-140521 A

By the way, the surface area of the power generation member (for example, a polycrystalline Si solar cell) provided in the portable electronic device is 4 [cm] × 7 [cm].
In this case, the generated power of the polycrystalline Si solar cell (hereinafter referred to as solar cell) is
4 [cm] × 7 [cm] × 100 [mW / cm ² ] × 0.17 = 476≈500 [mW]
become.

In addition, when the output current is maximized within a limited surface area, the voltage drops. Here, assuming that the output voltage of the solar cell is 0.5 [V], the maximum output current by the one-stage configuration of the solar cell is
500 [mW] ÷ 0.5 [V] = 1000 [mA]
become.

In addition, when the rechargeable battery is a Li-ion battery (rated 4.0 [V]), a circuit for boosting the voltage (0.5 [V]) output from the solar battery to 4.0 [V] or more is required. Become. In general, the efficiency of the DC-DC converter for boosting is about 80 to 85%, so the maximum charging current is
1000 [mA] × (0.5 ÷ 4.0) × 0.8 = 100 [mA]
become.

  Generally, as shown in FIG. 7, the charging circuit 200 is supplied from the solar cell 201, the charge pump 202 that raises the voltage supplied from the solar cell 201 to a certain voltage, and the charge pump 202. A booster circuit (DC-DC converter) 203 that boosts the voltage generated by the solar cell 201 to a certain voltage and a Li ion battery 204. The reason why the charge pump 202 is necessary is that the booster circuit 203 cannot be directly activated because the output voltage from the solar cell 201 is low.

  Here, problems of the charging circuit 200 shown in FIG. 7 will be described. In the charging circuit 200, when the impedance of the Li-ion battery 204 is low, especially when the voltage is low (eg, 3.6 V), the voltage of the solar battery 201 drops, the charge pump 202 cannot be started, and the booster circuit 203 Will also stop working. When the current stops flowing from the booster circuit 203 to the Li ion battery 204, the voltage of the solar cell 201 rises again, the charge pump 202 is activated, the booster circuit 203 operates, and the current starts to flow into the Li ion battery 204. . When the current starts to flow from the booster circuit 203 to the Li ion battery 204, the voltage of the solar cell 201 drops and no current flows from the booster circuit 203 to the Li ion battery 204.

  In the charging circuit 200, as shown in FIG. 8, the Li ion battery 204 is charged little by little while periodically repeating the phenomenon that voltage is applied to the Li ion battery 204 from the booster circuit 203 or not. However, there is a problem that charging efficiency is poor.

  The present invention has been made in view of the problems as described above, and one of the purposes thereof includes a power generation member in addition to the rechargeable battery, and when charging the rechargeable battery from the power generation member using a booster circuit, An object of the present invention is to provide a charging device capable of stably performing a charging operation on a rechargeable battery with a simple configuration.

In order to solve the above problems, a charging device according to the present invention has a power generation member whose power generation amount fluctuates in accordance with the surrounding environmental conditions, a booster circuit that boosts the voltage of the power generated by the power generation member, A secondary battery that is charged based on the electric power boosted by the booster circuit; and a current limiting circuit that limits a current supplied to the secondary battery between the booster circuit and the secondary battery. The current limiting circuit controls the amount of current supplied from the booster circuit to the secondary battery based on a relative variation in the voltage value of the electric power generated by the power generation member.

Moreover, in the said charging device, it is preferable that the said electric power generation member is comprised by the member from which electric power generation amount fluctuates according to the light reception amount which is the surrounding environmental condition.

  According to the present invention, the charging operation for the rechargeable battery can be performed stably.

  Embodiments of the present invention will be described below.

  FIG. 1 is an external perspective view of a mobile phone device 1 including a charging device according to the present invention. In the following, a mobile phone device will be described. However, the present invention is not limited to this, and any device having an imaging function and a communication function may be used. For example, PHS (registered trademark), PDA (Personal Digital) (Assistant), portable navigation device, notebook personal computer, or the like.

  The mobile phone device 1 includes an operation unit side body unit 2 and a display unit side body unit 3. The operation unit side body unit 2 includes an operation key group 11 and a microphone 12 into which a voice uttered by a user of the mobile phone device 1 is input on the surface unit 10. The operation key group 11 includes a function setting operation button 13 for operating various functions such as various settings, a telephone book function, and a mail function, and an input operation button 14 for inputting a telephone number and characters such as mail. And a determination operation button 15 for performing determination and scrolling in various operations.

  Further, the display unit side body unit 3 has a display 21 for displaying various information on the surface unit 20, an audio output unit 22 for outputting the voice of the other party on the call, and a CCD (Charge Coupled) for imaging the subject. (Device) An image pickup unit 23 constituted by a camera or the like and a speaker 24 for outputting music or the like to the outside are provided.

  In addition, since the image capturing unit 23 has an image capturing direction perpendicular to the display surface of the surface unit 20, the image capturing unit 23 captures an image when a person who holds and operates the mobile phone device 1 views the display 21 from the front. The direction is oriented in the direction in which the person's face is located. The imaging unit 23 may be provided on the surface portion 10 of the operation unit side body 2 instead of being provided on the display unit side body 3. In such a case, the imaging direction of the imaging unit 23 is also provided. The mobile phone device 1 may be held in the direction in which the face of the person who operates it is positioned.

  Further, the upper end of the operation unit side body 2 and the lower end of the display unit side body 3 are connected via a hinge mechanism 4. In addition, the cellular phone device 1 relatively rotates the operation unit side body 2 and the display unit side body 3 connected via the hinge mechanism 4, thereby The display unit side body 3 can be in a state of being open to each other (open state), or the operation unit side body 2 and the display unit side body 3 can be in a folded state (folded state).

  1 shows a form of a so-called foldable mobile phone device, but the form of the mobile phone device according to the present invention is not particularly limited to this, and the operation unit side body unit 2 and the display unit side body unit are not limited thereto. A slide type in which one housing is slid in one direction from a state in which the body portion 3 is overlapped, or an axis line along the overlapping direction of the operation portion side housing portion 2 and the display portion side housing portion 3 A rotary type (turn type) in which one casing is rotated around the center, and the operation section side casing section 2 and the display section side casing section 3 are arranged in one casing and have a connecting portion. There may be no type (straight type).

  FIG. 2 is a perspective view of the cellular phone device 1 in a folded state. The display unit side body 3 is provided with a power generation member 30 whose power generation amount varies according to the surrounding environmental conditions on the outer plane. The power generation member 30 is composed of, for example, a member (single-stage polycrystalline Si solar cell) whose power generation amount varies according to the amount of received light, which is the surrounding environmental condition, and a power supply circuit to be described later for the power generated by the power generation Supply to the department.

  FIG. 3 is a functional block diagram showing functions of the mobile phone device 1. As shown in FIG. 3, the cellular phone device 1 includes a communication unit 60 that communicates with an external terminal, a processing unit 70 that performs predetermined processing, and a power supply unit that supplies power to the communication unit 60 and the processing unit 70. 80.

  The communication unit 60 includes a main antenna 61 that communicates with an external device using a predetermined use frequency band, and a communication processing unit 62 that performs signal processing such as modulation processing or demodulation processing.

  The main antenna 61 communicates with an external device (base station) in a predetermined use frequency band (for example, 800 MHz). In the present embodiment, the predetermined use frequency band is 800 MHz, but other frequency bands may be used. Further, the main antenna 61 may have a so-called dual band compatible type that can support a second use frequency band (for example, 2 GHz) in addition to a predetermined use frequency band. You may be comprised by the type corresponding to multiple bands which can respond also to a use frequency band.

  The communication processing unit 62 demodulates the signal received by the main antenna 61, supplies the processed signal to the processing unit 70, and modulates the signal supplied from the processing unit 70, via the main antenna 61. To the external device (base station).

  The power supply unit 80 includes a rechargeable battery 81 having a predetermined capacity, a power generation member 30 that generates predetermined power, and a power supply circuit unit 82. The rechargeable battery 81 is, for example, a lithium ion secondary battery.

  The power supply circuit unit 82 converts the power supply voltage supplied from the rechargeable battery 81 into a predetermined voltage, supplies the converted voltage to the communication unit 60, the processing unit 70, and the like, and charges the rechargeable battery 81. Execute.

  Here, the charging operation will be described. When the rechargeable battery 81 starts to be charged from the discharged state, the power supply circuit unit 82 charges at a constant current because the initial voltage is low. When the power supply circuit unit 82 detects that the charging capacity gradually increases and the voltage value has reached a predetermined value, the power supply circuit unit 82 switches to charging with a constant voltage, and the voltage value does not exceed a predetermined value (for example, rated voltage). In this way, control is performed to reduce the current amount.

  As shown in FIG. 4, the power supply circuit unit 82 is driven by a charge pump 90 and an output voltage from the charge pump 90, and boosts a voltage generated by the power generation member 30 (DC-DC converter). 91 and a current limiting circuit 92 that limits the current supplied to the rechargeable battery 81 through the booster circuit 91. The power supply circuit unit 82 includes a step-up coil 93, a backflow-preventing Schottky diode 94, and a capacitor 95 having a certain capacity.

The charge pump 90 increases the voltage supplied from the power generation member 30 and supplies the increased voltage V _DD to the booster circuit 91.

The booster circuit 91 is activated based on the voltage V _DD supplied from the charge pump 90, boosts the voltage supplied from the power generation member 30 to a constant voltage, applies the boosted voltage to the current limiting circuit 92, Supply a constant current.

  The current limiting circuit 92 includes a transistor 92a and an FET 92b, and the collector terminal of the transistor 92a and the gate terminal of the FET 92b are electrically connected. The transistor 92a controls the switching operation of the FET 92b according to the voltage value (SLR_EN) applied from the power generation member 30, and the current flowing between the source and drain of the FET 92b is controlled according to the switching operation. The current limiting circuit 92 may be configured to limit the amount of current supplied from the booster circuit 91 to the rechargeable battery 81 in accordance with the voltage value (SLR_EN) applied from the power generation member 30. It may be.

  Here, the control of the current limiting circuit 92 during the charging operation for the rechargeable battery 81 will be described with reference to the flowchart shown in FIG.

  In step S1, the power generation member 30 generates predetermined power when a certain amount of light is irradiated.

In step S2, the charge pump 90 is supplied with the output voltage from the power generation member 30, and charges a certain amount of voltage. The charge pump 90 supplies a constant voltage V _DD to the booster circuit 91 when a certain amount of voltage is charged.

In step S <b> 3, the booster circuit 91 is activated when the constant voltage V _DD is supplied from the charge pump 90, boosts the voltage to a predetermined voltage, and outputs the boosted voltage to the current limiting circuit 92.

  In step S4, the current limiting circuit 92 controls the switching operation of the transistor 92a according to the voltage value (SLR_EN) supplied from the power generation member 30 in the step S1, and the source of the FET 92b is controlled according to the switching operation. The amount of current flowing between the drains is controlled.

  In this manner, the cellular phone device 1 according to the present invention is charged via the booster circuit 91 according to the power generation state of the power generation member 30, specifically according to the amount of power generated by the power generation member 30. The current value supplied to the battery 81 is controlled.

  For example, when the voltage of the rechargeable battery 81 is low (for example, 3.6 V), generally, current is suddenly supplied from the rechargeable battery 81, and thus the voltage of the power generation member 30 drops. However, in the present invention, when the voltage of the power generation member 30 (power generation voltage) starts to drop, the amount of current flowing through the FET 92b (switching operation in the FET 92b) is controlled according to the voltage value (SLR_EN) at that time. The rapid current supply to the battery 81 side is suppressed, and the output voltage of the power generation member 30 does not drop.

  Therefore, the cellular phone device 1 according to the present invention controls the amount of current supplied from the current limiting circuit 92 to the rechargeable battery 81 in accordance with the power generation state (power generated) in the power generation member 30. As shown in FIG. 6, the output voltage of the power generation member 30 is stabilized, and the rechargeable battery 81 can be stably charged.

  The power generation member 30 may be configured not only to charge the rechargeable battery 81 but also to supply a power supply voltage to a load (such as the processing unit 70) via the power supply circuit unit 82.

  In this embodiment, the charge pump 90 is disposed in the front stage of the booster circuit 91. However, if the booster circuit 91 is driven by the output power (about 0.5 V) from the power generation member 30 having a one-stage structure, The charge pump 90 may be omitted.

  In the present embodiment, the power generation member 30 is a polycrystalline Si solar cell, but is not limited thereto, and may be a fuel cell or the like.

It is a perspective view which shows the external appearance of the mobile telephone apparatus which concerns on this invention. It is a perspective view of the state which folded the mobile telephone apparatus shown in FIG. It is a block diagram which shows the function of the mobile telephone apparatus shown in FIG. It is a block diagram which shows the function of the power supply circuit part of the mobile telephone apparatus shown in FIG. It is a flowchart with which it uses for description about control of the current limiting circuit at the time of charge operation. It is a figure which shows the output voltage waveform of the electric power generation member which concerns on this invention. It is a block diagram which shows the function of the conventional power supply circuit part. It is a figure which shows the output voltage waveform of the conventional electric power generation member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cellular phone apparatus 30 Power generation member 60 Communication part 62 Communication processing part 70 Processing part 80 Power supply part 81 Rechargeable battery 82 Power supply circuit part

Claims (2)

A power generation member whose power generation amount varies depending on the surrounding environmental conditions;
A booster circuit that boosts the voltage of the power generated by the power generation member;
A secondary battery charged based on the electric power boosted by the booster circuit;
A current limiting circuit for limiting a current supplied to the secondary battery between the booster circuit and the secondary battery;
The current limiting circuit controls the amount of current supplied from the booster circuit to the secondary battery based on a relative variation in the voltage value of the power generated by the power generation member. . The generator member, the charging device according to claim 1, characterized in that it is constituted by a member fluctuating power generation amount according to the amount of light received is the surrounding environmental conditions.

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