JP2003084050A - Method of checking battery in digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make reference values in respective operation electric currents corresponding to driving conditions of a camera not required to be set respectively, and to detect a residual capacity of a battery without generating an error. SOLUTION: In this battery check method for the digital camera for measuring a terminal voltage to be A/D-converted, and for comparing an A/D-converted value therein with a reference voltage value for determination of the battery residual capacity to detect the battery residual capacity, respective electric current values in plural circuits are stored, an internal resistance of the battery is found based on a voltage value difference between the respective batteries under the condition where a consumed electric current is different in any of the circuits and the current value the corresponding circuit, a voltage value of the battery predicted in the reference current value is found based on the internal resistance value and the current under an operation at present, in an operation time of the camera, and the voltage value is compared with the reference voltage value for the determination of the battery residual capacity to detect the battery residual capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery check method for a digital still camera.

[0002]

2. Description of the Related Art In a digital still camera, a battery check is performed to detect the remaining capacity of the battery based on the terminal voltage of the battery. Such a battery check is generally performed for the following purpose.

1) Confirm that the camera operates properly. 2) Display the remaining amount on the display to inform the user of the replacement time.

The battery check method is usually carried out by dividing the terminal voltage of the battery, obtaining the voltage value by A / D conversion, and comparing this voltage value with a reference value.

When a current is applied to the battery, the terminal voltage of the battery decreases due to the internal resistance of the battery. The current value of the camera is different in each operation state such as a shooting standby state, shooting with the LCD monitor turned on, shooting without, and playback.

Since the current value in each operating state is different as described above, the discharge characteristics of the battery are also different. Therefore, the current consumption value in each operating state usually causes, for example, light load, medium load, heavy load, etc. Classify and have a fixed level judgment level (corresponding to A / D conversion value) corresponding to each load state, and
The determination is made by comparing the / D converted value with this value.

[0007]

Since the reference value for determination differs depending on the current (circuit load), it is set for each current value and stored in the EEPROM or the like. Since this value eliminates detection circuit error for each camera,
The value is adjusted by the adjustment process.

Various situations are conceivable for the driving state of the camera. For example, during standby (almost no current flows), when shooting with preview (CCD drive system, L
The CD monitor, the signal processing system, etc. are operated), and the reproduction is performed (the image processing system, the LCD monitor, etc. are operated). Moreover, focus driving, shutter driving, zoom driving, strobe charging, etc. are also added, and there are many combinations of current values.

FIG. 4 shows an outline of the voltage waveform of the battery when stroboscopic photography is performed using zoom. Thus, during zoom driving, when the release switches S1 and S2,
Since the current value is different during strobe charging,
It is difficult to determine and adjust the reference value by setting the reference value according to each discharge characteristic corresponding to these.

Further, the batteries are easily affected by the usage conditions (time and temperature), and the same battery and same operation (same current).
However, the internal resistance changes greatly depending on the temperature. For this reason, in the method of setting the reference value based on the discharge characteristic of each operating current and comparing, there are many errors in the determination.

Therefore, an object of the present invention is to provide a battery check method capable of detecting the remaining battery level without the need to set the reference value at each operating current corresponding to the driving state of the camera and without error. Especially.

[0012]

According to a first aspect of the invention for solving the above-mentioned problems, the terminal voltage of a battery is measured and A / D-converted, and the A / D-converted value and a reference for battery remaining amount determination. In a battery check method for a digital camera that detects the remaining battery level by comparing with a voltage value, each current value of a plurality of circuits is stored, and each circuit has a different current consumption. The internal resistance of the battery is calculated from the difference in the voltage value of the battery and the current value of the circuit, and the expected battery at the reference current is calculated from the internal resistance value and the current value of the circuit currently operating during camera operation. The battery check method for a digital camera is characterized in that the battery remaining amount is detected by obtaining the voltage value of the above and comparing this voltage value with a reference voltage value for battery remaining amount determination.

According to a second aspect of the present invention, there is provided a battery check method for a digital camera according to the first aspect, wherein the detection result of the remaining battery level is displayed on the display means.

The invention according to claim 3 is the battery check method for a digital camera according to claim 1 or 2, characterized in that the reference current value is a current at the maximum load of the camera.

According to a fourth aspect of the present invention, the battery check of the digital camera according to the first, second or third aspect is characterized in that the internal resistance value is updated at an arbitrary timing when the camera is activated or while the camera is operating. Is the way.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a block diagram showing an outline of a battery check function unit in a digital camera.

In this embodiment, the battery check function unit for checking the battery includes a battery voltage detection unit 1 for detecting the terminal voltage of the battery BA used, a battery check unit 2 for detecting the remaining battery amount, and a battery check unit. 2, a control unit 3 that performs control based on the detection result, a memory 4 that stores the current value of each drive circuit of the digital camera, and a battery display unit 5 that displays the detection result of the battery check unit 2.
Is configured.

The control unit 3 includes drive circuits of a digital camera, for example, a zoom control unit 6 for performing a zoom operation of a photographing lens, a focus control unit 7 for driving the photographing lens to focus a subject image, and an image. An LCD (liquid crystal display) monitor control unit 8 for displaying, a strobe charging control unit 9 for charging a strobe, a CCD system control unit 10 for controlling driving of a CCD as an image sensor, and a predetermined image data generated. An image processing control unit 11 that performs image processing is connected, and the control unit 3 controls the drive of each of these units.

The current value of the circuit in each of these parts is stored in the memory 4 in advance. The memory 4 is a non-volatile memory and, for example, an EEPROM or the like is used.

The current value of each circuit is 2 points (5.
The current value at a voltage of 0 V, 4.0 V) may be held as table data, or may be obtained from impedance or power consumption. Further, in the case where it varies depending on the input voltage, a plurality may be prepared according to the input voltage value.

The battery voltage detection unit 1 periodically or at a certain timing when the camera is activated or while the camera is operating.
The terminal voltage of the battery BA is measured. The measured voltage value is A
A / D converted, and output to the battery check unit 2 as an A / D converted value (Vad) of voltage.

The battery check unit 2 checks the remaining amount of the battery BA using the A / D converted value (Vad).
The battery check method will be described below with reference to the flowchart shown in FIG.

First, the battery check unit 2 acquires the A / D conversion value (Vad) of the voltage value of the battery BA (S).
1).

At this time, the battery check unit 2 obtains the internal resistance value (R) of the battery BA in advance. This internal resistance value (R) is calculated by using the zoom control unit 6, for example.
It can be determined by measuring the terminal voltage of the battery BA when the zoom is energized and not. That is, the current value of the circuit of the zoom control unit 6 is Izoom, the voltage during zoom driving is VzoomOn, and the voltage during zoom non-driving is VzoomOn.
If zoomOff is set, the internal resistance value (R) is obtained as follows.

R = (VzoomOff-VzoomOn) / Izoom

Any circuit other than the zoom control section 6 may be used as a circuit for energizing to obtain the internal resistance value (R).

Further, since the internal resistance value (R) varies not only with time factors but also with temperature, the internal resistance value (R) should be successively obtained at any timing during camera startup with the power turned on or during camera operation. It is preferable to update the value each time.

The internal resistance value (R) of the battery BA thus obtained is held in the battery check unit 2.

Next, the current value (I) of the circuit currently operating (during battery check) is read from the memory 4 (S
2) Using this current value (I) and the internal resistance value (R) of the battery BA, the voltage value (V) at the reference current is obtained (S3).

The voltage value (V) at this reference current is obtained as follows.

V = Vad- (Iref-I) * R

Here, Iref is a reference current value, which is held in the battery check unit 2 in advance. Then, the difference (Iref-I) between the reference current value (Iref) and the current value (I) of the circuit currently in operation is multiplied by the internal resistance value (R) of the battery BA already obtained, and the battery BA The difference between the voltage value and the A / D conversion value (Vad) is obtained, and the obtained voltage value (V) is compared with the reference voltage value (Vref) for battery remaining amount determination, thereby determining the battery remaining amount. Is determined.

In the present invention, the reference current value (Iref)
Is preferably a current value at the maximum load of the camera. By determining the remaining amount of the battery BA with reference to the current value at the maximum load of the camera, it becomes easy to guarantee all camera operations.

As the reference voltage value (Vref) for determining the battery remaining amount, the battery remaining amount is Full (FIG. 3A), Half
(FIG. 3 (b)) and Empty (FIG. 3 (c)) are visually displayed using an LCD monitor, a status display LCD, or the like, for example, Vref 70%, Vref 10
Each reference voltage value of% is used. These reference voltage values (Vref
) Is stored in the memory 4 in advance, and the comparison is performed by reading it out to the battery check unit 2.

Therefore, first, the voltage value (V) and Vref
70% is compared to determine whether V ≧ Vref 70% or not (S4).

If the result of this determination is Yes, it is determined that the battery level is 100%, and it is displayed on the display means such as the LCD monitor or the status display monitor that the battery is in the Full state as shown in FIG. 3 (a). Yes (S5).

If the determination result in S4 is No, then the above voltage value (V), Vref 70% and Vre
Comparing with f 10%, Vref 70%> V ≧ Vref 10%
It is determined whether or not (S6).

If the result of this determination is Yes, it is determined that the battery level is approximately 70%, and the display means such as the LCD monitor and the status display monitor is in the Half state as shown in FIG. 3B. Display (S7).

Further, when the result of the determination in S6 is No, it is determined that the remaining battery level is less than about 10%, and the LCD
As shown in FIG. 3C, it is displayed on the display means such as a monitor or a status display monitor that the status is Empty (S8).

Thus, the expected battery voltage value (V) at the reference current is obtained from the internal resistance value (R) of the battery and the current value (I) of the circuit currently in operation, and this voltage value is obtained. (V)
And the reference voltage value (Vref) for battery remaining amount determination are compared to determine the battery remaining amount. Therefore, as in the conventional case, the reference value at each operating current corresponding to the driving state of the camera is determined. There is no need to set each.

Further, in order to obtain the expected voltage value (V) of the battery at the reference current, the internal resistance value (R) of the battery BA is obtained.
Therefore, the remaining battery level can be detected without error.

When the reference current value (Iref) is the current value at the maximum load of the camera, the reference voltage value (Vref) is the minimum voltage value at which the camera can operate, and as a result of the comparison between the two, V ≦ It is also preferable to prohibit the normal operation of the camera at the time of Vref. In this case, it is preferable that the normal operation such as photographing is prohibited, and the LCD monitor or the status display monitor is used to display the voltage drop of the battery BA to the user or turn off the camera.

When obtaining the expected battery voltage value (V) at the reference current, an error due to A / D conversion and an error due to calculation are included. In particular, the reference current value (Iref
) And the actual current value are significantly different, the error increases. Therefore, the display of the remaining amount may not be constant,
In order to prevent this, it is preferable that the reference voltage value (Vref) has a width so that the changed display is not restored.

[0045]

According to the present invention, there is provided a battery check method capable of detecting the remaining battery level without the need to set the reference value for each operating current corresponding to the driving state of the camera and without error. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a battery check function unit in a digital camera.

FIG. 2 is a flowchart showing a battery check method.

3A to 3C are diagrams showing an example of a battery remaining amount display.

FIG. 4 is a diagram showing an outline of a voltage waveform of a battery. 1: Battery voltage detector 2: Battery check section 3: Control unit 4: Memory 5: Battery display

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G016 CA04 CB06 CB12 CB24 CC01                       CC04 CC06 CC16 CE03                 5C022 AA13 AC42 AC69 AC73                 5G003 BA01 DA02 EA05 GC05                 5H030 AA03 AA04 AA08 AS11 FF42                       FF44 FF68

Claims (4)

[Claims] 1. A terminal voltage of a battery is measured and A / D converted,
In a battery check method for a digital camera that detects the remaining battery level by comparing the A / D converted value with a reference voltage value for remaining battery level determination, the current values of a plurality of circuits are stored. , The internal resistance of the battery is obtained from the difference between the voltage values of the batteries in which the current consumption is different in one of the circuits and the current value of the circuit, and at the time of camera operation, the internal resistance value and the current operating circuit From the current value of, the expected battery voltage value at the reference current is obtained, and the remaining battery level is detected by comparing this voltage value with the reference voltage value for battery remaining level determination. How to check battery of digital camera. 2. The battery check method for a digital camera according to claim 1, wherein the detection result of the remaining battery level is displayed on the display means. 3. The battery check method for a digital camera according to claim 1, wherein the reference current value is a current at the maximum load of the camera. 4. A battery check method for a digital camera according to claim 1, 2 or 3, wherein the internal resistance value is updated at the time of starting the camera or at any timing during the operation of the camera.