JP4262412B2 - Battery end-of-discharge voltage setting device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a discharge end voltage setting device that sets a preset discharge end voltage value of a battery.
[0002]
[Prior art and its problems]
In a conventional portable device using a battery as a driving power source, the battery voltage is periodically checked, and when the battery voltage reaches a predetermined discharge end voltage value, the user is notified that there is no remaining battery power and the battery is replaced. The use of the battery is prohibited by prompting or stopping the operation of the device.
However, the ESR (series equivalent resistance) of the battery varies depending on the use environment, and particularly when the battery is used in a low-temperature environment of 0 ° C. or lower, the ESR of the battery rapidly increases (see FIG. 5). ). Therefore, if the end-of-discharge voltage value is set to be constant regardless of the usage environment as shown in FIG. 6, the battery voltage immediately reaches the end-of-discharge voltage value in a low temperature environment, and the battery energy is sufficiently increased. Could not be used up.
[0003]
OBJECT OF THE INVENTION
An object of the present invention is to provide a discharge end voltage setting device for a battery that can improve the use efficiency of the battery with a simple configuration based on the above problem awareness.
[0004]
Summary of the Invention
The present invention includes a battery, a position detecting means for detecting the current position on the earth, a clock means for measuring the date and time, a memory means for storing a temperature data table for each region and each date, and the position detecting means. The region is identified from the location information, the date is identified from the date and time information of the clock means, the corresponding current temperature data is read from the temperature data table, and the discharge end voltage of the battery is based on the read temperature data And a setting means for setting a value.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a control system of an electronic still camera to which the present invention is applied. The camera 10 includes an MPU 11 as a control unit that comprehensively controls camera operations. The MPU 11 includes a ROM 11a that stores a control program and parameters, a RAM 11b that temporarily stores control data, and a time counter 11c. The voltage of the battery 12 loaded in the camera 10 is supplied to the MPU 11 as a constant voltage via the power supply circuit 13. The MPU 11 is operated by a constant voltage supplied from the power supply circuit 13 and performs processing according to each switch state of the operation unit 20. The operation unit 20 is provided with a plurality of operation switches such as a GPS function switching switch 20a for switching whether to activate a GPS 33, which will be described later, and a date setting switch 20b for setting date information. Further, the MPU 11 monitors the battery voltage via the first A / D conversion circuit 14 so as to take a countermeasure such as giving a warning to the photographer before the battery voltage reaches the discharge end voltage value.
[0006]
A DSP 15 is connected to the MPU 11. In the DSP 15, a second A / D conversion circuit 16 that converts an analog image signal output from the image sensor 17 into a digital image signal and outputs the digital image signal, and a display unit 22 that displays an image captured by the image sensor 17 and information related to shooting. The image memory 24 for storing the digital image signal output from the second A / D conversion circuit 16 is connected. The MPU 11 controls display processing by the display unit 22 via the DSP 15, and controls imaging processing by the image sensor 17 via the DSP 15 and the second A / D conversion circuit 16.
[0007]
In addition, the MPU 11 receives an RTC (Real Time Clock) 31 that measures and holds the date (year / month / day) and time (hour / minute / second) and a radio wave transmitted from a GPS satellite to identify the current position on the earth. A GPS (Global Positioning System) 33 that outputs position information and a sub CPU 35 are connected. The RTC 31, the GPS 33, and the sub CPU 35 are supplied with a constant voltage output from the power supply circuit 13 as drive power.
The RTC 31 is provided with a backup power source 32. That is, the RTC 31 is supplied with power from the battery 12 via the power supply circuit 13 when the power of the camera 10 is on, and is supplied with power from the backup power supply 32 when the power of the camera 10 is off. Can work. The MPU 11 recognizes the current date and time based on the signal input from the RTC 31, and counts the subsequent time with the time counter 11c.
[0008]
The sub CPU 35 includes a ROM that stores a control program and a RAM that temporarily stores parameters, and a nonvolatile memory 37 is connected as an external memory. The nonvolatile memory 37 stores an air temperature data table in which temperature data is arranged for each region and month, and a correction data table for setting an end-of-discharge voltage value according to the ambient temperature of the camera 10. These stored data can be rewritten, for example, by downloading from another information device. As the non-volatile memory 37, for example, an EEPROM (flash memory) can be used. The non-volatile memory 37 may be an IC memory card that can be attached to and detached from the camera 10. In this case, data in units of regions is stored in the IC memory card, and the IC memory card is exchanged according to the region where the camera 10 is used. Can also be configured.
[0009]
FIG. 2A is an image diagram of a temperature data table stored in the nonvolatile memory 37. In this embodiment, the earth is divided into a plurality of regions in advance, and the temperature transition data table for each month from January to December is stored in the nonvolatile memory 37 for each region. As shown in the graphs of FIGS. 2B and 2C, the temperature transition data table represents the average temperature transition of the corresponding month on the first day (from 0:00 to 24:00).
The above-mentioned regional division is arbitrary. For example, it is divided into the northern hemisphere and the southern hemisphere with the equator as a boundary, and each of the northern hemisphere and the southern hemisphere is divided into 10 regions for each predetermined latitude, so that a total of 20 regions can be set.
[0010]
The sub CPU 35 identifies the temperature transition data table corresponding to the current date and time in the region including the current position of the user (camera 10) from the temperature data table, and the temperature data corresponding to the current time from the identified temperature transition data table. Is read out, the ambient temperature of the camera 10 can be specified. Further, in this embodiment, the end-of-discharge voltage value of the battery is uniquely determined with respect to the ambient temperature of the camera 10 and stored in the nonvolatile memory 37 as a correction data table. The sub CPU 35 can obtain a correction value for the discharge end voltage by reading a correction value corresponding to the read temperature data (ambient temperature) from the correction data table. FIG. 3 shows an example of a correction data table when a two-cell type lithium battery (general-purpose) is used as the battery 12. When the ambient temperature is high, the fluctuation of the ESR of the battery is small and the correction data becomes almost constant. Therefore, in this embodiment, correction data corresponding to the ambient temperature of 25 ° C. to −20 ° C. is provided. The number of significant digits of the correction value varies depending on the resolution of the first A / D conversion circuit 14.
[0011]
The camera 10 configured as described above corrects the discharge end voltage value of the battery 12 according to the ambient temperature of the camera 10. When the battery voltage falls below the end-of-discharge voltage value, a warning is given on the display unit 22, the camera operation is stopped, and the battery 12 is prohibited from discharging. Hereinafter, the setting operation of the discharge end voltage value will be specifically described with reference to FIG.
[0012]
When the power of the camera 10 is turned on by the user (S1), the power supply circuit 13 is activated, power supply from the battery 12 to each circuit and element is started, and the MPU 11 is activated. When the MPU 11 is activated, the default value of the discharge end voltage stored in the ROM 11a is set as the discharge end voltage value in the RAM 11b as an initial operation, and information necessary before photographing such as the current date is displayed on the display unit 22. Is done. Next, the MPU 11 inputs and sets the current date / time information from the RTC 31 (S2). At this time, if there is a user date setting operation, the date information is changed in response to the user operation. Then, the MPU 11 determines whether or not to acquire position information based on the state of the GPS function selector switch 20a (S3).
[0013]
When acquiring the position information, the MPU 11 activates the GPS 33 (S4), and inputs the current position information (latitude, longitude) from the GPS 33 (S5). Subsequently, the MPU 11 outputs the current position information and the current date / time information based on the count value of the time counter 11a to the sub CPU 13 (S6).
[0014]
Based on the input position information and date and time information, the sub CPU 13 specifies an area corresponding to the current position from a plurality of areas divided in advance, and specifies a month corresponding to the current date and time (S7, S8). Next, the sub CPU 13 specifies the temperature transition data table corresponding to the region and month specified in S7 and S8 from the temperature data table stored in the nonvolatile memory 37 (S9). Then, the sub CPU 13 reads temperature data corresponding to the current time from the specified temperature transition data table, and determines this temperature data as the current ambient temperature of the camera 10 (S10). For example, in the case of FIGS. 2B and 2C, if the current position is region 1 and the current date is noon in April, the temperature data is 21.5 ° C., and the same region 1 is the same in December. If it is time, temperature data will be 5.2 degreeC.
After determining the ambient temperature, the sub CPU 13 reads the correction data corresponding to the current ambient temperature from the correction data table stored in the nonvolatile memory 37 (S11), and outputs this correction data to the MPU 11 (S12). In FIG. 3, for example, if the ambient temperature is 22 ° C., the correction data is 6.1538 V, and if the ambient temperature is 5 ° C., it is 5.892 V.
[0015]
The MPU 11 overwrites the correction data input from the sub CPU 13 on the RAM 11b as a discharge end voltage value (S13), and displays the current position information on the display unit 22 (S14). Then, the MPU 11 detects the voltage of the battery 12 and compares it with the discharge end voltage value (S15, S16). If the battery voltage is equal to or lower than the discharge end voltage value, the display unit 22 has no remaining battery level. Is displayed and the power of the camera 10 is turned off (S16; Y, S17, S18). If the battery voltage is not lower than the discharge end voltage value in S16, the operation from S4 is repeated again (S16; N).
[0016]
The above is the operation for acquiring the position information. However, when the position information is not acquired (S3; N), the discharge end voltage value is not corrected. Therefore, the MPU 11 detects the voltage of the battery 12 to detect the discharge end voltage. Compared to (default value) (S15, S16), the battery voltage is monitored in the same manner as in the case of acquiring the above-described position information.
The end-of-discharge voltage value stored in the RAM 11b is erased when the camera 10 is turned off.
[0017]
As described above, in this embodiment, since the discharge end voltage value of the battery 12 is set according to the ambient temperature of the use date and time at the place where the camera 10 is used, the discharge capacity of the battery in each use environment can be maximized. . In particular, the energy of the battery 12 can be used up even in a low temperature environment.
In this embodiment, temperature data is stored in the non-volatile memory 37 as climate information. However, the end-of-discharge voltage value may be corrected by storing climate information such as weather information and humidity information. Data other than climate information can be stored upon request.
[0018]
As the battery 12, a dedicated secondary battery may be used, or a general-purpose battery (primary / secondary) may be used. When a dedicated battery is used, a correction data table for the dedicated battery is stored in the nonvolatile memory 37. On the other hand, when using a general-purpose battery, the characteristics differ depending on the manufacturer of the battery to be used, but by measuring discharge characteristics of a plurality of manufacturers in advance and storing a plurality of correction data tables in the nonvolatile memory 37. An appropriate discharge end voltage value can be set. However, in this case, the user needs to specify the manufacturer of the battery to be used by operating the switch.
[0019]
In this embodiment, the GPS 33 is built in the camera 10, but the GPS 33 may be provided as an option that can be attached to and detached from the camera 10.
[0020]
The embodiment in which the discharge end voltage setting device of the present invention is mounted on an electronic still camera has been described above. However, the present invention is applicable to various portable devices that use a battery as a drive power source.
[0021]
As mentioned above, although this invention was demonstrated according to the Example, this invention can be changed unless it deviates from the range, and of course, it is not limited to the said Example.
[0022]
【The invention's effect】
According to the present invention, since an appropriate discharge end voltage of the battery is set according to the use environment, the use efficiency of the battery can be improved with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a control system of an electronic still camera equipped with a battery final discharge voltage setting device of the present invention.
FIG. 2A is an image diagram of a temperature data table. (B) is the figure which represents the temperature data table of April in the area 1 of (a) in a graph. (C) is a figure which represents the temperature data table of December in the area 1 of (a) in a graph.
FIG. 3 is a diagram illustrating an example of a correction data table.
FIG. 4 is a flowchart showing an end-of-discharge voltage setting operation of the camera.
FIG. 5 is a diagram showing temperature dependence of ESR (equivalent series resistance) of a general battery.
FIG. 6 is a diagram comparing discharge characteristics when a battery is used in a normal temperature environment and when a battery is used in a low temperature environment.
[Explanation of symbols]
10 Camera 11 MPU
31 RTC
33 GPS
35 Sub CPU
37 Nonvolatile memory

Claims (5)

Battery,
Position detection means for detecting the current position on the earth;
Clock means for timing the date and time;
Memory means storing temperature data tables by region and date and time;
An area is specified from the position information of the position detection means, a date is specified from the date information of the clock means, and the corresponding current temperature data is read from the temperature data table, and the battery is based on the read temperature data Setting means for setting the discharge end voltage value of
A discharge final voltage setting device for a battery, comprising: 2. The battery end-of-discharge voltage setting device according to claim 1 , wherein the memory means includes, as the temperature data table, an average in each month from January to December for each region on the earth arbitrarily divided. Battery end-of-discharge voltage setting device in which typical daily temperature transition data is stored for each month. The battery discharge end voltage setting device according to claim 2 , wherein the memory means further stores a correction data table of a discharge end voltage corresponding to the ambient temperature,
The setting means, the area specifying means for specifying a region corresponding to the temperature data table on the position information and, identifying the temperature transition data table of the month corresponding to the date information in the area of the temperature data table which is the specific Date and time specifying means for performing; temperature specifying means for reading out temperature data corresponding to the time information from the specified temperature transition data table to obtain a current ambient temperature; and correcting the correction data corresponding to the current ambient temperature A discharge end voltage setting device for a battery, comprising: a discharge end voltage value determining unit that reads from a data table and uses the correction data as the discharge end voltage value. In the discharge end voltage setting device cell according to any one of claims 1 to 3, wherein the memory means, the discharge end voltage setting device of the battery is a nonvolatile memory capable of rewriting the stored data. The discharge end voltage setting device for a battery according to any one of claims 1 to 4 , further, a display means for displaying various information,
Battery check means for periodically detecting the voltage of the battery and comparing it with the discharge end voltage value, and determining that the battery check is NG when the detected voltage is lower than the discharge end voltage value;
If the battery check means determines that the battery check is NG, the control means for causing the display means to display that there is no remaining battery power and prohibiting discharge of the battery;
An end-of-discharge voltage setting device for a battery.

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