JP4291712B2 - Battery level detection method - Google Patents

Description

  The present invention relates to a remaining battery level detection method for detecting a remaining battery level in an electrical device.

  For example, a DC / DC converter of an electric device has a regulation of a power supply voltage and is provided with a function of turning off an output for protection when a voltage outside the regulation is applied.

  In electrical equipment, if the power is suddenly turned off during operation, there is a possibility of destroying data such as ROM. Therefore, if the battery voltage is detected and falls below a certain preset voltage, the power of the electrical equipment is forced. To come off.

  However, in digital cameras, power consumption during normal operation has been reduced, but power consumption when driving a motor such as a lens has not been reduced so much, and the load during driving the lens and during normal operation (when not driving the lens) is reduced. The rate of change is increasing.

  As described above, when the power consumption rapidly changes, there is a case where the voltage that is higher than the end voltage in the steady state becomes equal to or lower than the DC / DC converter protection voltage due to the internal impedance of the battery or the circuit.

  As a method for solving this, a method described in Patent Document 1 is raised.

  In the method described in Patent Document 1, a judgment is made so that the remaining battery level becomes insufficient when a low level state is continued for a certain period so that a temporary voltage drop is not erroneously detected as insufficient battery level. Yes.

However, when a battery that has been used up for a while after it has been used up is used in a device, even if it is above the specified voltage when checked with a dummy load, it is shorter than the above-mentioned fixed period while it is still in use. The battery voltage drops suddenly over the period and falls below the specified voltage of the DC / DC converter, and the device may not be able to force the power off properly and destroy the data in the storage means (ROM, etc.) Is
JP-A-8-271597

  The present invention has been made to solve the above problem, and provides a battery remaining amount detection method capable of detecting a battery voltage even when a device suddenly changes its load and normally turning off the device. The purpose is to do.

  In order to achieve the above object, the battery remaining amount detecting method according to claim 1 is a battery remaining amount detecting method for detecting a remaining battery amount of a device including a plurality of devices having different load sizes driven by a battery. The voltage comparison measurement between the battery voltage and the reference voltage corresponding to the device is performed at regular intervals during the operation of the device, and the voltage of the battery is lower than the reference voltage corresponding to the active device. The comparison result is compared by comparing the counting process for counting the number of times, the number of voltage comparison measurements in which the battery voltage has dropped below the reference voltage corresponding to the device in operation, and the number of times of voltage drop recognition set in advance for each device. An output comparison step, wherein the number of voltage drop recognitions of a device with a large load is set to be smaller than the number of voltage drop recognitions of a device with a small load.

  In the battery remaining amount detection method according to the first aspect, during the operation of the apparatus, voltage comparison measurement between the battery voltage and the reference voltage corresponding to the apparatus is performed at regular intervals.

  In the counting step, the number of times that the voltage of the battery has dropped below the reference voltage corresponding to the operating device is counted.

  In the comparison step, the number of times that the battery voltage has dropped below the reference voltage corresponding to the device in operation is compared with the number of times of voltage drop recognition provided for each device, and a comparison result is output.

  For example, when a certain device operates, the reference voltage of the operated device and the battery voltage are compared at regular intervals, and the number of times that the battery voltage has dropped below the reference voltage is preset. When the number of times is reached, it is determined that the remaining battery level is low. For example, a comparison result indicating that the remaining battery level is low is output.

  Here, when a device with a large load is activated, power consumption is larger than when a device with a small load is activated. For example, when the remaining battery level is low, the voltage drops rapidly and the remaining battery level May decrease at once.

  For this reason, by setting a small number of settings for a heavily loaded device, it is possible to detect the battery end when the heavily loaded device is operating, and the device can perform a normal end sequence based on the comparison result. It becomes.

  The devices include, for example, an image sensor, a lens that forms a subject image on the image sensor, a driving device that drives the lens to focus, and a recording medium that performs predetermined processing on the image signal output from the image sensor A digital camera equipped with a control device for recording can be raised.

  As described above, according to the present invention, there is an effect that the power of the device can be normally turned off even when the load of the device suddenly changes.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram of an electric system of a digital camera to which the battery remaining amount detection method of the present invention is applied.

  In FIG. 1, reference numeral 10 is a control device including a CPU, an A / D converter, etc., reference numeral 12 is a motor driver for driving an iris motor, reference numeral 14 is a motor driver for driving a focus and zoom motor, Reference numeral 16 is a strobe, reference numeral 17 is a shutter device, reference numeral 18 is an image sensor (CCD or the like), reference numeral 20 is a timing generator, reference numeral 22 is a CDSAMP, reference numeral 24 is an A / D converter, reference numeral 26 is an image input controller, reference numeral 28. Is an image processing signal circuit, symbol 30 is a compression processing circuit, symbol 32 is a GPS position conversion circuit, symbol 34 is a video / LCD encoder, symbol 36 is an image display device (LCD), symbol 36 is an AF (autofocus) detection circuit, Reference numeral 40 is an AE & AWB detection circuit, reference numeral 42 is a memory (SDRAM), reference numeral 44 is VRAM, reference numeral Reference numeral 6 denotes a media controller, reference numeral 48 denotes a recording medium for recording image data of a photographed image, reference numeral 50 denotes a USB interface, reference numeral 52 denotes a DC / DC converter, reference numeral 54 denotes a battery, reference numeral 56 denotes a shutter device 17 for operating the shutter device 17. A switch, symbol 58 is a menu button (switch), and symbol 60 is a shooting / playback switching button (switch).

  The control device 10 includes a battery voltage detection unit that detects the battery voltage Vs of the battery 54.

  In the control apparatus 10, a plurality of reference voltages (battery end voltages) according to the magnitude of the load, in this embodiment, a high reference voltage VH for steady state (low load) and a low reference voltage VL for high load are used. A reference voltage is set (stored).

  As shown in FIG. 2 and FIG. 3, the battery voltage Vs changes variously by driving the load.

  FIG. 2 is an example of a voltage waveform at the time of shooting, and FIG. 3 is an example of a voltage waveform at the time of a through movie (a state in which the image content being captured by the CCD 18 is displayed on the image display device 36 in real time). .

  The control device 10 is in a steady state (when a low-load device is operating. For example, when the CCD 18 performs imaging but each motor is stopped and the strobe is not charged.) The comparison between the battery voltage Vs and the reference voltage VH is performed by a comparator. When a high-load device is operating (for example, when the iris motor is operating), the battery voltage Vs of the battery 54 and the reference voltage VL are compared. The comparison is performed with a comparator.

  In the present embodiment, the CPU performs 10 ms polling as the comparison operation, and in a steady state, as shown in FIG. 4A, the number of comparisons that the battery voltage Vs is lower than the reference voltage VH is 20 times. When reaching the above, the control device 10 performs end processing of the device.

  Therefore, for example, a voltage drop at the time of driving an iris or a shutter is not detected.

  On the other hand, when a high-load device is activated, for example, when the iris or shutter is driven, as shown in FIG. 4B, if the number of comparisons that the battery voltage Vs is lower than the reference voltage VL is one, The control device 10 performs end processing of the device.

  For this reason, according to the present embodiment, the battery end can be detected even during a sudden load change during a high load operation, and a normal end sequence of the operation of the digital camera is possible.

  The number of comparisons between the battery voltage and the reference voltage is not limited to that in the above embodiment.

  In the above embodiment, two reference voltages are provided. However, the present invention is not limited to this. For example, the reference voltage has three reference voltages having different values according to low load, medium load, and high load devices. The number of times of polling is not limited to the number of times of the above embodiment.

  In the above embodiment, the battery remaining amount detection method of the present invention is applied to a digital camera. However, the battery remaining amount detection method of the present invention can be applied to all devices using a battery as a power source.

It is a block diagram of the electric system of a digital camera. It is an example of the voltage waveform at the time of imaging | photography. It is an example of the voltage waveform at the time of a through movie. (A) is an example of a voltage waveform at high load, and (B) is an example of a voltage waveform at steady state.

Explanation of symbols

10 Control device 12 Motor driver (high load)
14 Motor driver (high load)
16 Strobe (high load)
17 Shutter (High load)
54 batteries

Claims (2)

A battery remaining amount detection method for detecting a remaining battery amount of a device having a plurality of devices with different load sizes driven by a battery,
During the operation of the device, voltage comparison measurement between the battery voltage and the reference voltage corresponding to the device is performed at regular intervals, and the number of voltage comparison measurements when the battery voltage is lower than the reference voltage corresponding to the operating device is counted. Counting process;
A comparison step of comparing the number of times of voltage comparison measurement in which the voltage of the battery is lower than the reference voltage corresponding to the device in operation and the number of times of voltage reduction recognition set in advance for each device, and outputting a comparison result;
With
A method for detecting a remaining battery level, wherein the number of times of voltage drop recognition of a device with a large load is set to be smaller than the number of times of voltage drop recognition of a device with a small load.   The device includes an image sensor, a lens that forms a subject image on the image sensor, a driving device that drives the lens to focus, and a control that performs predetermined processing on the image signal output from the image sensor and records it on a recording medium. The battery remaining amount detection method according to claim 1, wherein the method is a digital camera including the device.

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