JP3772034B2 - Battery remaining amount notification device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery remaining amount notification device that is built in a small portable electronic device such as a digital still camera that can be driven by a battery and notifies a user of the remaining amount of the battery.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a small portable electronic device that can be driven by a battery, a method for informing the user of the remaining battery level and the degree of consumption by a battery mark, a character character, or the like has been proposed. The small portable electronic device here is a dry battery such as a digital still camera, a portable music CD (compact disc) drive device, a portable cassette tape recording / reproducing device, an MD (mini disc) drive, and a PDA (information portable terminal). Anything that can be driven.
[0003]
For example, a video camera that uses a dedicated battery, such as a video camera, is known in which a battery level measurement circuit and a display function are provided on the battery side to indicate the battery level.
[0004]
By the way, in a small portable electronic device using a general dry battery, for example, Japanese Patent Application Laid-Open No. 3-108960, Japanese Patent Application Laid-Open No. 8-205414, Japanese Patent Application Laid-Open No. 9-7644, etc. As shown in FIG. 4, a method for determining the remaining battery level by detecting the load current flowing in a small portable electronic device or the battery terminal voltage directly has been proposed.
[0005]
However, with the above method, it is possible to know the relative remaining amount of the battery, but it is difficult to actually know how much time the battery has from this remaining amount. For example, when applied to a digital still camera The user cannot obtain information such as how many images can be captured and how long the liquid crystal display can be continued. For this reason, inconveniences such as turning off the power of the device during use or missing the subject when it is important.
[0006]
[Problems to be solved by the invention]
As described above, the battery remaining amount detection method described above can know the relative remaining amount of the battery, but it is difficult to know how much the battery actually has from this remaining amount of time. Has inconvenience.
[0007]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a battery remaining amount notification device capable of obtaining an absolute battery remaining amount while using a general battery and notifying a user of a remaining usable time from the remaining amount. There is to do.
[0008]
[Means for Solving the Problems]
A battery remaining amount notification device according to the present invention is a device built in an electronic device that includes a load circuit that is driven by a battery and generates a load current according to the driving state, and a display that displays the state of the battery. The battery terminal voltage is converted into a voltage required by the load circuit and supplied to the load circuit, and a pulsed waveform signal corresponding to the load current generated from the load circuit is generated and used. The DC / DC converter circuit for controlling the voltage conversion process, the integration means for integrating the pulsed waveform signal output from the DC / DC converter circuit, the output of the integration means, and the terminal voltage of the battery are selectively selected. Switching derivation means for deriving switching, analog / digital conversion means for converting the output derived by the switching derivation means into digital data, and the type of battery in advance. Characteristic storage means for storing the attached discharge characteristic value and the characteristic value of the DC / DC converter circuit, battery type information input means for inputting battery type information from the outside, and input by the battery type information input means A battery that reads the corresponding discharge characteristic value and the characteristic value of the DC / DC converter circuit from the characteristic storage unit based on the type information, and calculates the remaining amount of the battery using the read result and the output of the analog / digital conversion unit It is characterized by comprising: a remaining amount calculating means; and a display control means for displaying information indicating the remaining amount of the battery calculated by the remaining battery amount calculating means on the display.
[0009]
According to this configuration, the discharge characteristic value corresponding to the battery type and the characteristic value of the DC / DC converter circuit are stored in advance in the characteristic storage unit, and the battery type information is input by the user. The discharge characteristic value and the characteristic value of the DC / DC converter circuit are read out, and the remaining amount of the battery is calculated by using these values and the load current information and battery terminal voltage information obtained by the DC / DC converter circuit. By displaying the information indicating the remaining amount on the display, it is possible to obtain an absolute real-time remaining amount of the battery depending on the type of the battery.
[0010]
For this reason, the user can grasp the current power consumption state and the remaining usable time based on the remaining amount of the battery, so that it is easy to avoid various troubles due to running out of the battery.
[0011]
Further, in the above-described configuration, when the electronic device operates in two or more types of operation modes, an expected value storage unit that stores predicted power consumption values respectively associated with a plurality of types of operation modes, and a plurality of types of Monitoring means for monitoring the operation mode, the battery remaining amount calculating means is based on the type information input by the battery type information input means, the corresponding discharge characteristic value and the DC / DC converter circuit of the DC / DC converter circuit Based on the type of operation mode detected by the monitoring means and reading out the characteristic values, the corresponding power consumption expected values are read out from the predicted value storage means, and these discharge characteristic values, the DC / DC converter circuit characteristic values, and the power consumption The remaining amount of the battery is calculated using the predicted value and the output of the analog / digital conversion means.
[0012]
According to this configuration, the predicted value storage means stores power consumption predicted values respectively associated with a plurality of types of operation modes, automatically detects the type of operation mode, and based on the detection result, The estimated power consumption value is read out, and the remaining battery power is combined with the load current information obtained by the DC / DC converter circuit, the battery terminal voltage information, the discharge characteristic value corresponding to the battery type, and the DC / DC converter circuit characteristic value. By being subjected to the amount calculation process, it becomes possible to obtain an absolute and real-time remaining battery capacity corresponding to the operation mode.
[0013]
In the above configuration, the display control means has means for displaying the power consumption status and the remaining usable time in real time on the display based on the remaining battery level calculated by the remaining battery level calculation means. Therefore, the user can easily recognize how much the battery has, and can be aware of power saving, and as a result, can contribute to an increase in operating time and the like.
[0014]
Further, in the above configuration, the information display device further includes information transfer means for transferring the battery remaining amount information calculated by the battery remaining amount calculation means to / from an external device, so that the display is turned off. Even so, the battery remaining amount information can be displayed on the display of another device, and the user can easily obtain the battery remaining amount information, which is convenient.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a circuit block diagram showing an embodiment of a battery remaining amount notification device according to the present invention. The battery remaining amount notification device includes a load circuit 2 that is driven by the battery 1 and generates a load current corresponding to the driving state, and a display 3 that displays the state of the battery 1, for example, a digital still camera or the like. Built in electronic equipment.
[0016]
Reference numeral 11 in the figure denotes a DC / DC (direct current / direct current) converter circuit which converts the terminal voltage of the battery 1 into a voltage required by the load circuit 2 and supplies it to the load circuit 2, and a load generated from the load circuit 2. A DC pulse-shaped PWM (Pulse Width Modulation) signal whose duty changes according to the current state is generated, and the voltage conversion process is controlled using this PWM signal.
[0017]
The PWM signal obtained by the DC / DC converter circuit 11 is subjected to impedance conversion by the buffer 12 and then smoothed to a DC voltage by the integration circuit 13. That is, the output of the integrating circuit 13 is input to the switch unit 14 as load current information indicating the state of the load current. Battery voltage information indicating the terminal voltage of the battery is input to the other end of the switch unit 14. Here, switching of the switch unit 14 is appropriately switched by control from the control unit 15, and load current information or battery voltage information is derived and output to the A / D (analog / digital) converter 16. The A / D converter 16 converts the output of the switch unit 14 into digital data and outputs the digital data to the control unit 15.
[0018]
The control unit 15 is connected to the display 3, the storage unit 17, and an input unit 18 for inputting type information indicating the type of the battery 1 by a user operation, and further includes a mode monitoring unit 151, A remaining amount calculating unit 152 and a display control unit 153 are provided. The storage unit 17 stores a control program and control data used by the control unit 15, and further stores a discharge characteristic value associated with the type of the battery 1 and a characteristic value of the DC / DC converter circuit 11 in advance. And a power consumption prediction table 172 that stores predicted power consumption values respectively associated with a plurality of types of operation modes.
[0019]
The mode monitoring means monitors these operation modes when the digital still camera operates in two or more operation modes.
[0020]
The remaining amount calculation means 152 reads the corresponding discharge characteristic value and the characteristic value of the DC / DC converter circuit 11 from the characteristic table 171 of the storage unit 17 based on the type information of the battery 1 input by the input unit 18, and Based on the type of operation mode detected by the mode monitoring unit 151, the corresponding power consumption prediction value is read from the power consumption prediction table 172 of the storage unit 17, and these discharge characteristic values, the characteristic values of the DC / DC converter circuit 11, The remaining amount of the battery 1 is calculated using the predicted power consumption value and the output of the A / D converter 16.
[0021]
The display control unit 153 displays the remaining amount of the battery 1 calculated by the remaining amount calculation unit 152 on the display unit 3 to notify the user.
[0022]
The control unit 15, the A / D converter 16 and the storage unit 17 can be realized in a general-purpose microcomputer (hereinafter referred to as a microcomputer), and use the functions of the microcomputer originally incorporated in the product. May be.
[0023]
The display 3 may be various user interfaces such as an alarm LED and a liquid crystal display, but it goes without saying that the means and implementation method are not limited in the content of the present invention.
[0024]
FIG. 2 shows a specific configuration of the DC / DC converter circuit 11.
That is, the electric power generated from the battery 1 is turned on / off by the switching element Tr after passing through the inductor L, and becomes DC output via the rectifier diode D and the smoothing capacitor C. The DC output is fed back to the DC / DC converter IC 111 as a voltage determined by the division ratio of the resistors R1 and R2, and a reference voltage value generated from the reference voltage generation circuit 111a by the operational amplifier 111a inside the DC / DC converter IC 111. Is converted into an error voltage value corresponding to the comparison result and supplied to the PWM waveform generation circuit 111c.
[0025]
As shown in FIG. 3A, the PWM waveform generation circuit 111c compares the error voltage value output from the operational amplifier 111a with the internal sawtooth waveform for generating PWM, and outputs the PWM output as the base terminal of the switching element Tr. To turn on / off the switching element Tr.
[0026]
Here, when the feedback voltage is high, a pulse signal having a short H (high) period (ON period) shown in FIG. 3B is input to the base terminal of the switching element Tr. On the contrary, when the feedback voltage is low, FIG. Since the duty ratio is controlled so that a pulse signal having a long H section shown in (c) is input, a desired voltage can be obtained even if the load varies.
[0027]
Conversely, when the load is heavy (when the load side pulls a lot of current), the duty ratio of the PWM waveform is steadily small (H section → small) and the load is light (current consumption on the load side) When the amount is small), the duty ratio becomes large.
[0028]
That is, the duty ratio of the PWM output waveform is inversely proportional to the weight of the load. Therefore, if the PWM output waveform is smoothed, it is possible to know the state of the load (current consumption) from the smoothed voltage.
[0029]
The present invention is characterized by applying the above principle and detecting a load current with a relatively simple circuit configuration by utilizing an existing circuit system.
[0030]
Next, an example of a specific method for calculating the remaining amount of the battery 1 in the control unit 15 will be described with reference to FIGS. Here, a method for calculating the remaining amount of the battery 1 according to the type of the battery 1 will be described.
FIG. 4 shows voltage-discharge capacity characteristics of a general dry battery used as the battery 1. Here, in order to express the load current, the nominal capacity is 1, and the ratio is N, which is expressed in units of NC. For example, in a battery having a nominal capacity of 1000 mAh, 1C = 1000 mA (200 mA for 0.2C).
[0031]
The reason why the power supply voltage changes depending on the load current is mainly due to the internal resistance of the battery. However, at a certain constant load current, the discharge capacity is uniquely determined from the battery voltage. That is, in a 1000 mAh battery having the characteristics shown in FIG. 4, if the terminal voltage when a load current of 0.2 C is passed is 1.25 V, the total discharge capacity can be calculated to be about 600 mAh. If 1.2 V (800 mAh) is set as the input voltage limit value in the DC / DC converter circuit 11 of the corresponding product in consideration of temperature characteristics and measurement accuracy, the remaining capacity can be converted to 800−600 = 200 mAh. . In this state, if 100 mA is consumed on the load side, the product can be operated for another 2 hours, and if 200 mA is consumed, it means that only 1 hour is left.
[0032]
On the other hand, FIG. 5 shows an example of the difference in voltage-discharge capacity characteristics due to the battery.
That is, the characteristics vary greatly depending on the type of battery (alkali, manganese, secondary battery, etc.), and therefore the type of battery needs to be considered when calculating the remaining usable time. Since it is generally difficult for the product side to automatically detect the type information indicating the type of battery, it is desirable that the user should initially set the minimum information using the input unit 18.
[0033]
In this embodiment, the discharge characteristic value and the voltage limiter value that is the characteristic value of the DC / DC converter circuit 11 are stored in the characteristic table 171 corresponding to the type of the battery. The characteristic value may be obtained by calculating with a microcomputer using an approximate curve or the like.
[0034]
Next, an example of the battery terminal voltage and load current detection timing by the control unit 15 will be described.
When the battery terminal voltage is detected, for example, every time the product is powered on, a constant current load state is established for a certain period of time, and the battery terminal voltage value during that period is converted into digital data by the A / D converter 16, and the controller 15 Detect with. At this time, the control unit 15 switches the switch 14 to the battery 1 side. Thereafter, in the operating state, the control unit 15 detects the digital data of the PWM integral value every certain period to obtain the load current value. Since the relationship between the PWM integral value and the consumption current depends on the characteristics of the DC / DC converter circuit 11, conversion from the A / D conversion value to the current value may be stored as a table in the storage unit 17. Needless to say, the conversion formula may be used.
[0035]
Next, an example of a battery remaining amount calculation method according to the operation mode in the control unit 15 will be described.
That is, in a product field such as a digital still camera, power consumption may vary depending on combinations of strobe usage, liquid crystal usage, and image sensor usage conditions. That is, even in the shooting mode, the load current varies depending on the presence or absence of strobe light emission, display / non-display of the liquid crystal, image size, and the like. Also, the load current generally increases considerably from the stand-by state, although it is temporarily during the actual “shooting” and “recording on the media”, although it is temporarily.
[0036]
Normally, there are several modes to be switched such as a dial type and a liquid crystal menu selection format, but the user often wants to know the approximate number of remaining images to be captured when various modes are switched. Here, there is a method of using a “prediction mode” that assumes a certain use condition for each mode in order to know in advance “how many images can be taken” in advance.
[0037]
In the prediction mode, for example, assuming continuous shooting at 1 minute intervals, the current consumption value when using the strobe, the current consumption value of the image sensor, the standard average current consumption value in the liquid crystal display, etc. It memorize | stores in the memory | storage part 17 and uses it for a calculation.
[0038]
That is, for each mode, information such as an increase of +50 mA / frame when shooting in the flash mode, and an increase of +200 mA / frame when there is no liquid crystal display is set for each mode. Using the information and the remaining capacity calculated above, the number of images that can be taken in each mode can be roughly known in advance (when the settings such as the dial are changed).
[0039]
Note that the remaining usable time and the number of remaining shots can be displayed on a liquid crystal display or the like different from the display 3 so that the user can obtain information even when the display 3 is turned off. It becomes. In this case, the control unit 15 transfers real-time information indicating the remaining usable time and prediction information indicating the remaining number of shots to another liquid crystal display or the like via the terminal 19.
[0040]
In addition, the control unit 15 may selectively switch between the real-time information and the prediction information and display it on the display 3 or may always display it simultaneously.
[0041]
Further, the display control means 153 of the control unit 15 has a load current monitor function for displaying the current consumption value itself on the display 3 in real time on the display 3 based on the calculated remaining amount of the battery 1. If this is done, the user can be alerted to power consumption and conscious of power saving.
[0042]
As described above, according to the above embodiment, the discharge characteristic value corresponding to the type of the battery 1 and the characteristic value of the DC / DC converter circuit 11 are stored in advance in the characteristic table 171 of the storage unit 17, and the battery 1 is stored by the user. Is input to the input unit 18, the corresponding discharge characteristic value and the characteristic value of the DC / DC converter circuit 11 are read out, and these values and the output of the DC / DC converter circuit 11 are integrated into the integrating circuit 13. The control unit 15 calculates the remaining amount of the battery 1 using the load current information and the battery terminal voltage information obtained from the PWM integral value integrated in step 1, thereby making the absolute real-time battery 1 depending on the type of the battery 1 available. The remaining usable time can be converted from the remaining amount of the battery 1, and the remaining amount is indicated thereafter. Information is displayed on the display device 3.
[0043]
For this reason, since the user can grasp the current power consumption status and the remaining usable time based on the information indicating the remaining amount of the battery 1 displayed on the display 3, it avoids various troubles caused by running out of the battery. Easy to do.
[0044]
In addition, by storing power consumption prediction values associated with a plurality of types of operation modes in the power consumption prediction table 172 of the storage unit 17, the control unit 15 automatically detects the type of operation mode. Based on the detection result, the corresponding expected power consumption value is read, and the load current information obtained from the PWM integrated value obtained by integrating the output of the DC / DC converter circuit 11 by the integrating circuit 15, the battery terminal voltage information, and the battery 1 By using the discharge characteristic value corresponding to the type and the characteristic value of the DC / DC converter circuit 11 for battery remaining amount calculation processing, an absolute real-time battery remaining amount corresponding to the operation mode is obtained. Is possible.
[0045]
Furthermore, the display control means 153 of the control unit 15 displays the power consumption status and the remaining usable time on the display 3 in real time based on the remaining amount of the battery 1 calculated by the load current monitoring function. Therefore, the user can easily recognize how much the battery 1 has, and can raise awareness of power saving, and as a result, can contribute to the increase in operating time, the number of images taken, and the like.
[0046]
Further, since the control unit 15 can transfer the calculated remaining amount information of the battery 1 to another liquid crystal device or the like via the terminal 19, even when the display device 3 is turned off, The remaining amount information of one can be displayed on another liquid crystal display, and the user can easily obtain the remaining amount information of the battery, which is convenient.
[0047]
In addition, each circuit configuration and the calculation method in the control unit 15 can be variously modified and implemented without departing from the present invention.
[0048]
【The invention's effect】
As described above in detail, according to the present invention, the remaining battery level that can be used to determine the absolute remaining battery level while using a general battery, and to inform the user of the remaining usable time from this remaining level. A notification device can be provided.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing a configuration of an electronic apparatus to which an embodiment of a battery remaining amount notification device according to the present invention is applied.
2 is a circuit block diagram showing a specific configuration of the DC / DC converter circuit shown in FIG.
FIG. 3 is a waveform diagram for explaining PWM output in the DC / DC converter circuit.
4 is a voltage-discharge capacity characteristic diagram of a general dry battery used for arithmetic processing of the control unit shown in FIG.
FIG. 5 is a voltage-discharge capacity characteristic diagram of a battery used for arithmetic processing of the control unit shown in FIG.
[Explanation of symbols]
1 ... Battery
2 ... load circuit,
3 Display,
11 ... DC / DC converter circuit,
12 ... buffer,
13 ... Integral circuit,
14 ... switch part,
15 ... control unit,
16 ... A / D converter,
17 ... storage unit,
18 ... Input section,
19 ... terminal,
151... Mode monitoring means,
152... Remaining amount calculating means
153 ... display control means,
171 ... Characteristic table,
172 ... Electricity consumption prediction table.

Claims (4)

A device built in an electronic device that includes a load circuit that is driven by a battery and generates a load current according to the driving state, and a display that displays the state of the battery,
The terminal voltage of the battery is converted into a voltage required by the load circuit and supplied to the load circuit, and a pulsed waveform signal corresponding to the load current generated from the load circuit is generated and used. A DC / DC converter circuit for controlling the voltage conversion process;
Integrating means for integrating the pulsed waveform signal obtained by the DC / DC converter circuit;
Switching deriving means for selectively deriving the output of the integrating means and the terminal voltage of the battery;
Analog / digital conversion means for converting the output derived by the switching derivation means into digital data;
Characteristic storage means for storing in advance the discharge characteristic value associated with the type of battery and the characteristic value of the DC / DC converter circuit;
Battery type information input means for inputting the battery type information from the outside;
Based on the type information input by the battery type information input unit, the corresponding discharge characteristic value and the characteristic value of the DC / DC converter circuit are read from the characteristic storage unit, and the read result and the analog / digital conversion unit Battery remaining amount calculating means for calculating the remaining amount of the battery using the output,
A battery remaining amount notification device comprising: display control means for displaying the battery remaining amount information calculated by the battery remaining amount calculating means on the display. A device built in an electronic device that is driven by a battery and includes a load circuit that generates a load current according to the driving state, and a display that displays the state of the battery. There,
The terminal voltage of the battery is converted into a voltage required by the load circuit and supplied to the load circuit, and a pulsed waveform signal corresponding to the load current generated from the load circuit is generated and used. A DC / DC converter circuit for controlling the voltage conversion process;
Integrating means for integrating the pulsed waveform signal obtained by the DC / DC converter circuit;
Switching deriving means for selectively deriving the output of the integrating means and the terminal voltage of the battery;
Analog / digital conversion means for converting the output derived by the switching derivation means into digital data;
Characteristic storage means for storing in advance the discharge characteristic value associated with the type of battery and the characteristic value of the DC / DC converter circuit;
Predicted value storage means for storing predicted power consumption values respectively associated with a plurality of types of operation modes;
Battery type information input means for inputting the battery type information from the outside;
Monitoring means for monitoring the plurality of operation modes;
Based on the type information input by the battery type information input unit, the corresponding discharge characteristic value and the characteristic value of the DC / DC converter circuit are read from the characteristic storage unit, and the operation mode detected by the monitoring unit is read. Based on the type, the corresponding predicted power consumption value is read from the predicted value storage means, and the discharge characteristic value, the characteristic value of the DC / DC converter circuit, the predicted power consumption value, and the output of the analog / digital conversion means are used. Battery remaining amount calculating means for calculating the remaining amount of the battery,
A battery remaining amount notification device comprising: display control means for displaying information indicating the remaining battery amount calculated by the remaining battery amount calculating means on the display. The display control means includes means for displaying the power consumption status and the remaining usable time on the display in real time based on the remaining battery level calculated by the remaining battery level calculating means. The battery remaining amount notification device according to claim 1 or 2, characterized in that: 3. The battery remaining amount notification device according to claim 1, further comprising information transfer means for transferring battery remaining amount information calculated by the battery remaining amount calculating means to / from an external device.

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