JP2007263828A - Battery remaining amount management device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine accurately a battery remaining amount in consideration of an influence of a temperature or a load. <P>SOLUTION: This battery remaining amount management device for an apparatus (for example, a mobile printer) driven by a battery (lithium ion battery) determines an internal resistance (DCIR) of the battery from a battery temperature (t), determines a no-load voltage (V0) from a battery voltage (V), the internal resistance (DCIR), and the power (W) used by the apparatus by means of the expression: no-load voltage (V0)=V+DCIR×W/V, and determines the battery remaining amount by using a correspondence table of the battery remaining amount between the battery temperature and the no-load voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for managing the remaining amount of a battery.

  In a battery-driven device such as a mobile printer, there is a method of reading the battery voltage as a method of managing the remaining battery level at a low cost (see Patent Document 1).

JP 2002-86848 A

  However, the battery voltage varies depending on the environmental temperature and load. In a device having a large load fluctuation, accurate remaining amount management cannot be performed if the remaining amount of the battery is obtained with a certain fixed voltage threshold.

  For example, as shown in FIG. 5, the internal resistance of the battery increases as the temperature decreases. Therefore, as shown in FIG. 6, with a certain load, the battery voltage decreases at a low temperature, and the battery voltage increases at a high temperature. Naturally, since there is an internal resistance, the battery voltage decreases when a large load is applied, and the battery voltage increases when the load is light. At this time, for example, if it is determined that there is no remaining battery power based on whether or not it falls below a certain fixed voltage threshold, the battery voltage becomes lower when a large load is applied in a low temperature environment, so that energy remains in the battery. It is determined that there is no remaining battery power.

  The present invention has been made to solve the above-described problems, and an object thereof is to more accurately determine the remaining battery level.

  In order to solve the above-mentioned problem, a first aspect of the present invention is a battery remaining amount management device, which uses the means for obtaining the internal resistance of the battery and the internal resistance to obtain the no-load voltage of the battery. A battery remaining amount management device comprising: a no-load voltage calculating means; and a means for obtaining a remaining battery level using the no-load voltage.

  According to a second aspect of the present invention, there is provided a battery remaining amount management device, comprising: a means for acquiring battery voltage; a means for acquiring battery temperature; and a predetermined calculation formula, from the battery temperature. Means for obtaining an internal resistance of the battery; and a no-load voltage calculating means for obtaining a no-load voltage from the battery voltage, the internal resistance, and power used by the device, using a predetermined calculation formula; The battery remaining amount corresponding to the battery temperature and the no-load voltage obtained by the no-load voltage calculating means is obtained using a predetermined relationship between the battery temperature, the no-load voltage and the remaining battery amount. A battery remaining capacity management device.

The no-load voltage calculation means has the following formula:
(No load voltage) = (Battery voltage) + (Internal resistance) x (Equipment power consumption) / (Battery voltage)
Thus, the no-load voltage can be obtained.

  The power usage of the device may be determined based on the current mode of the device.

  The battery may be a lithium ion battery.

  FIG. 1 is a schematic configuration diagram of a printer 1 to which a battery remaining amount management device according to an embodiment of the present invention is applied. The printer 1 is a portable so-called mobile printer that is driven by a battery 30 as a power source. The printer 1 is also a direct printer that can read and print image data directly from a memory card or the like without being connected to a host such as a personal computer.

  The printer 1 includes a print processing unit 10 that executes a printing process that is an original function of the printer, and a battery management unit 20 that manages the remaining amount of the battery 30.

  The print processing unit 10 includes an operation panel including a liquid crystal display and an input device, a control unit that analyzes a request from a user and generates image data for printing, and printing that performs printing by an inkjet method or the like. It consists of an engine.

  The battery management unit 20 calculates the remaining amount of the battery 30. In general, the voltage of the battery 30 (referred to as “battery voltage”) is monitored, the battery surface temperature determined from the battery voltage, the voltage of the thermistor (temperature sensor) 31 attached to the battery 30, and the use of the print processing unit 10. The no-load voltage, which is a voltage when there is no load on the battery 30, is calculated from the power that is generated and the internal resistance (DCIR) of the battery 30. Then, the remaining battery level (energy) is obtained from the calculated no-load voltage using a predetermined table.

  The battery 30 is a lithium ion battery.

  These functional units can be realized in software or hardware.

  For example, the control unit and the battery management unit 20 of the print processing unit 10 include a CPU that is a main control device, a ROM that stores programs and the like, a RAM that temporarily stores data and the like as a main memory, and between each device And a system bus serving as a communication path. The battery management unit 20 may be achieved by a separate circuit from the control unit of the print processing unit 10 or may be achieved by software using the same circuit.

  The battery 30 can be removable from the printer 1. Further, it may be removable together with the thermistor 31.

  Further, such a battery management unit 20 may be a microcomputer (not shown) built in a battery pack including the battery 30. Therefore, the battery remaining amount management device and the management method thereof according to the present embodiment may be incorporated in the battery pack. In this case, the battery pack includes the battery 30, the thermistor 31, and the microcomputer constituting the battery management unit 20. The battery pack may be removable from the printer 1.

  Hereinafter, a method for obtaining the remaining battery level (energy) of the printer 1 configured as described above will be specifically described.

  The main factor that changes the battery voltage depending on the environmental temperature and load is the internal resistance. Therefore, in this embodiment, the no-load voltage of the battery 30 that can ignore the influence of the internal resistance is used for the remaining amount management of the battery 30. That is, using a table that associates the no-load voltage and the battery remaining amount, the remaining amount (energy) of the battery 30 is calculated by referring to where the no-load voltage is located in the table.

  Therefore, first, the battery management unit 20 acquires the thermistor voltage (Vs). The thermistor voltage (Vs) is converted from the thermistor voltage (Vs) detected from the thermistor 31 and the battery temperature (t) using a conversion table as shown in FIG. Ask. Note that this conversion table is stored in the battery management unit 20 in advance.

Next, the battery management unit 20 calculates an internal resistance (DCIR) from the battery temperature (t) using a predetermined relational expression. Here, the formula used for the calculation is predetermined based on the measured values of the battery temperature (t) and the internal resistance (DCIR). For example, in the same relationship as FIG. 5, it is expressed as the following formula (1).
DCIR = -0.0018t ³ + 0.2994t ² -16.997t + 649.9 [mΩ] ・ ・ ・ Formula (1)

  Next, the battery management unit 20 checks the power (W) used in the print processing unit (that is, the “main body” of the printer 1) 10. Specifically, the power consumption (W) corresponding to the current printer mode is specified using information associating the printer mode with the power usage as shown in FIG. The printer mode includes “printing mode”, “standby mode”, “low power mode”, and the like. Information regarding the power used for each mode is stored in the battery management unit 20 in advance.

Next, the battery management unit 20 measures the battery voltage (V) from the output of the battery 30. Furthermore, a no-load voltage (V0) is calculated from the battery voltage (V), internal resistance (DCIR), and power consumption (W) using the following formula (2).
V0 = V + DCIR × W / V Expression (2)

Instead of specifying the power consumption (W) corresponding to the printer mode, the current value (I) is measured by a current sensor provided in the printer 1 as a device or in the battery pack in the power supply path. In place of the above equation (2),
It is also possible to obtain V0 as V0 = V + DCIR × I.

  Next, as shown in FIG. 4, using the battery remaining amount correspondence table in which the battery temperature (t), the no-load voltage (V0), and the battery remaining amount ratio (%) are associated, The amount ratio (%) is obtained.

  As shown in the figure, the no-load voltage (V0) 402 and the remaining battery ratio (%) 403 are associated with each other in the battery temperature band 401 having a certain width in the battery remaining capacity correspondence table. Stored. That is, if the battery remaining amount conversion table is used, the battery remaining amount ratio (%) is obtained from the battery temperature (t) and the no-load voltage (V0).

  The battery management unit 20 specifies which battery temperature band the battery temperature (t) belongs to in the battery remaining capacity correspondence table. Then, in the battery temperature band, the remaining battery ratio (%) that gives the no-load voltage (V0) obtained by the above equation (2) is obtained.

  Here, as shown in FIG. 4, the remaining battery rate (%) in the remaining battery level correspondence table is a jump value such as 5%, 10%, 15%... ) And the remaining battery ratio (%) are approximated as having a linear relationship in a narrow range. That is, the battery remaining rate (%) of the no-load voltage (V0) obtained by the above formula (2) is specified between which battery remaining rate (%) in the battery remaining amount correspondence table. When it is between A% and B%, the battery remaining rate (%) and the no-load voltage (V0) are in a linear relationship between them, and are approximated by a straight line and obtained by the above equation (2). Further, the remaining battery ratio (%) of the no-load voltage (V0) is obtained. Note that the slope of the approximate line at this time is given by [(BA) / {(B% no-load voltage) − (A% no-load voltage)}].

  Next, the battery management unit 20 obtains the energy when the battery remaining amount ratio is 100% from the battery remaining amount correspondence table, and obtains the current battery remaining amount ratio obtained above to the value of 100% energy. Multiply (%) to obtain the remaining battery level (Wh).

  The method for obtaining the remaining battery capacity has been described above.

  Processing according to the remaining battery level of the printer 1 varies depending on how it is set. For example, when the remaining battery level is 2 Wh or less, the battery management unit 20 instructs the print processing unit 10 to turn off the power. In response to this, the print processing unit 10 turns off the power.

  The print processing unit 10 also instructs the battery management unit 20 to calculate the remaining battery level when the user requests display of the remaining battery level via the operation panel, and acquires the calculated remaining battery level. Then, the display on the operation panel may be displayed.

  The embodiment of the present invention has been described above.

  According to the embodiment, since the no-load voltage is used, it is possible to more accurately determine the battery remaining amount while suppressing the influence of temperature and load.

  The present invention is not limited to the above embodiment. The above embodiment can be variously modified. For example, in the above embodiment, the present invention is applied to a printer. However, the present invention is not limited to this, and can be applied to a battery-driven device. For example, the present invention can be applied to mobile devices such as mobile DVDs and mobile electric drills, and portable devices.

  Further, the present invention is not limited to the case where the battery is a lithium ion battery, but can be applied to a battery having temperature characteristics such that the battery voltage changes depending on the temperature.

1 is a schematic configuration diagram of a printer to which an embodiment of the present invention is applied. The figure which shows the relationship table | surface between a thermistor voltage and battery temperature. The figure which shows the relationship table of printer mode and electric power used. The figure which shows a battery remaining charge conversion table. The figure which shows the relationship between internal resistance and battery temperature. The figure which shows the relationship between a battery voltage and a discharge time characteristic.

Explanation of symbols

1 ... Printer,
DESCRIPTION OF SYMBOLS 10 ... Print processing part, 20 ... Battery management part, 30 ... Battery, 31 ... Temperature sensor

Claims (7)

A battery level management device,
Means for determining the internal resistance of the battery;
No-load voltage calculation means for obtaining the no-load voltage of the battery using the internal resistance;
Means for determining the remaining battery level using the no-load voltage. A battery level management device,
Means for obtaining battery voltage;
Means for obtaining battery temperature;
Means for determining the internal resistance of the battery from the battery temperature using a predetermined calculation formula;
No-load voltage calculation means for obtaining a no-load voltage from the battery voltage, the internal resistance, and the power used by the device using a predetermined calculation formula,
Means for obtaining a battery remaining amount corresponding to the battery temperature and the no-load voltage obtained by the no-load voltage calculating means, using a predetermined relationship between the battery temperature, the no-load voltage and the remaining battery amount. A battery remaining capacity management device comprising: It is a battery remaining charge management apparatus of Claim 2, Comprising:
The no-load voltage calculation means has the following formula:
(No load voltage) = (Battery voltage) + (Internal resistance) x (Equipment power consumption) / (Battery voltage)
A battery remaining amount management device characterized in that a no-load voltage is obtained. It is a battery remaining charge management apparatus of Claim 2, Comprising:
The battery remaining power management apparatus characterized in that the power used by the device is determined based on a current mode of the device. It is a battery remaining charge management apparatus of Claim 1 or 2,
The battery is a lithium ion battery. A battery level management method,
Determining the internal resistance of the battery;
Using the internal resistance, a no-load voltage calculation step for obtaining a no-load voltage of the battery;
And a step of obtaining a remaining battery level using the no-load voltage. A battery level management method,
Obtaining a battery voltage;
Obtaining a battery temperature;
Using a predetermined calculation formula, obtaining the internal resistance of the battery from the battery temperature;
Using a predetermined calculation formula, a no-load voltage calculation step for obtaining a no-load voltage from the battery voltage, the internal resistance, and the power used by the device;
A step of obtaining a remaining battery level corresponding to the battery temperature and the no-load voltage obtained by the no-load voltage calculation step using a predetermined relationship between the battery temperature, the no-load voltage and the remaining battery level. A method for managing the remaining battery level.

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