JP2001147258A - Device and method for monitoring voltage and digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for voltage monitoring which give a more adequate alarm according to the state of equipment and a digital camera which can use them. SOLUTION: The battery voltage of the power source of portable equipment having at least a 1st and a 2nd mode is monitored. A comparison voltage selection part 312 selects and outputs a 1st specific voltage provided corresponding to the 1st mode in the 1st mode and selects and outputs a 2nd specific voltage which is provided corresponding to the 2nd mode and different from the 1st given voltage in the 2nd mode. A lowest voltage comparison part 314 compares the current battery voltage with the value outputted from the comparison voltage selection part 312. An alarm process part 316 performs a predetermined alarm processing when it is decided that the battery voltage is lower than the value outputted from the comparison voltage selection part 312.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for monitoring battery voltage. In particular, the present invention relates to a voltage monitoring device that monitors a battery voltage of a device operable on a battery and performs a predetermined alarm process when the battery voltage becomes lower than a predetermined value.

[0002]

2. Description of the Related Art Conventionally, as a method for evaluating the remaining amount of a battery power supply, a voltage value of the battery power supply has been measured. FIG. 1 is a diagram showing a general discharge curve when a battery power supply is used. The horizontal axis indicates time, and the vertical axis indicates voltage. The voltage of the battery power, immediately after the start power supply, indicates the rated voltage greater than the battery power supply, immediately drops to the voltage V ₀ which rated. Thereafter, it continues to supply power while maintaining a substantially constant V _0. When the capacity of the battery decreases, the voltage value decreases rapidly,
When the voltage value reaches V _D stops the supply of electric power. Therefore, defining the alarm voltage V _A as the lowest voltage that can supply power from the battery power between V ₀ and V _D, when it reaches the V _A, that warn the user before the V _D To notify the user's convenience.

[0003]

However, the voltage value is V
_Since it rapidly decreases near _D and remains almost constant up to VD, it is generally difficult to determine the warning timing, that is, _VA .

[0004] Therefore, since a voltage higher than _VA is actually set as _VA , the battery must be replaced with the remaining battery capacity, and the battery cannot be used to the end.

Accordingly, an object of the present invention is to provide a voltage monitoring device that issues a more appropriate warning according to the status of equipment. JP-A-7-99734 (publication date: April 11, 1995) and JP-A-7-325133 (publication date: December 12, 1995) correctly warn even if the voltage drop amount fluctuates. Discloses a voltage monitoring device that emits light.
However, there is a strong demand for more detailed monitoring / warning technology for today's products in which the modes realized by the devices are various.

Accordingly, an object of the present invention is to provide a voltage monitoring device, a voltage monitoring method, and a digital camera that can use them, which can solve the above-mentioned problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous embodiments of the present invention.

[0007]

According to a first aspect of the present invention, there is provided an apparatus for monitoring a battery voltage in a power supply of a portable device having at least a first mode and a second mode. This device selects and outputs a first predetermined voltage provided corresponding to the first mode in the case of the first mode, and corresponds to the second mode in the case of the second mode. And a comparison voltage selection unit that selects and outputs a second predetermined voltage different from the first predetermined voltage, and a minimum voltage that compares the battery voltage with a value output from the comparison voltage selection unit. A comparison unit; and an alarm processing unit that performs a predetermined alarm process when it is determined that the battery voltage is lower than the value output from the comparison voltage selection unit.

[0008] The portable device may further include first and second electric circuits. The first mode may be a mode in which power is supplied from the power supply to the first electric circuit, and the second mode is a mode in which power is supplied from the power supply to the second electric circuit. It may be.

[0009] The first predetermined voltage may be a lower limit value of the battery voltage that permits supply of power from the power supply to the first electric circuit.
It may be a lower limit value of the battery voltage that permits supply of power from the power supply to the second electric circuit.

[0010] When the first mode is a mode in which the load on the power supply is lighter than that in the second mode, the alarm processing section determines whether the battery voltage is equal to the first predetermined voltage in the first mode. When it becomes lower than that, it may be possible to switch to the second mode. A mode determination unit that detects a request to switch from the second mode to the first mode; and a switching permission / prohibition voltage that determines whether to permit switching from the second mode to the first mode with respect to a battery voltage in the second mode. And a switching permission / prohibition voltage comparing section that compares the battery voltage with the switching permission / prohibition voltage comparing section.The alarm processing section may also check a comparison result of the switching permission / prohibition voltage comparing section when the switching request is detected. Good.

[0011] The switching permission / prohibition voltage may be such that the battery voltage in the second mode is such that if the switching from the second mode to the first mode occurs, the battery voltage shifts to the first predetermined voltage. It may be.

[0012] The alarm processing section may prohibit switching to the first mode when the battery voltage is lower than the switching permission / prohibition voltage in the second mode.

[0013] The alarm processing section may instruct output of an alarm sound as the alarm processing.

A second aspect of the present invention is a digital camera operable on battery power. The digital camera includes a processing unit that comprehensively controls the operation of the digital camera, and the processing unit includes a voltage monitoring device that monitors the battery voltage of the power supply. The voltage monitoring device includes a first mode in which the power supply supplies power to a first electric circuit of the digital camera, and a second mode in which the power supply supplies power to a second electric circuit of the digital camera.
A mode determination unit that determines which mode of the mode is selected; and, in the case of the first mode, a lower limit value of the battery voltage that permits supply of power from the power supply to the first electric circuit. A certain first alarm voltage is selected and output, and in the case of the second mode, a second alarm voltage that is a lower limit value of the battery voltage that permits supply of power from the power supply to the second electric circuit is set. A comparison voltage selection unit for selecting and outputting, a lowest voltage comparison unit for comparing the battery voltage with a value output from the comparison voltage selection unit,
An alarm processing unit that performs predetermined alarm processing when it is determined that the battery voltage is lower than the value output from the comparison voltage selection unit.

[0015] The first electric circuit may be an image pickup unit for picking up an image, and the second electric circuit may be an audio unit for outputting sound in accordance with an instruction from the processing section.

The alarm processing unit may instruct the audio unit to output an alarm sound.

A third aspect of the present invention is a method of monitoring a battery voltage in a power supply of a portable device having at least a first mode and a second mode. This voltage monitoring method is
In the case of the first mode, a first alarm voltage provided corresponding to the first mode is selected. In the case of the second mode, a second alarm voltage provided corresponding to the second mode is selected. And a comparing step of comparing the battery voltage with the value of the alarm voltage selected by the selecting step; and when the battery voltage is lower than the alarm voltage value selected by the selecting means. A warning stage for performing a predetermined alarm process.

The above summary of the present invention does not enumerate all of the necessary features of the present invention, and sub-combinations of these features may also constitute the present invention.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described through embodiments of the present invention. However, the following embodiments do not limit the claimed invention and have the features described in the embodiments. Not all combinations are essential to the solution of the invention.

FIG. 2 is a configuration diagram of the digital camera 10 operable with a battery power supply according to the embodiment. The digital camera 10 mainly includes an imaging unit 20, a processing unit 60, a display unit 100, an operation unit 110, and an audio unit 200. First, an entire digital camera including a voltage monitoring device for monitoring a battery voltage according to the present embodiment will be described with reference to FIG. The voltage monitoring device according to the present embodiment will be described in detail with reference to FIG.

The image pickup unit 20 includes a mechanism member and an electric member related to photographing and image formation. Imaging unit 20
First, a photographing lens 22 for capturing and processing images,
An aperture 24, a shutter 26, an optical LPF (low-pass filter) 28, a CCD 30, and an image signal processing unit 32 are included. The taking lens 22 includes a focus lens, a zoom lens, and the like. With this configuration, the subject image is
Image on the light receiving surface of. Charges are accumulated in each sensor element (not shown) of the CCD 30 according to the amount of light of the formed subject image (hereinafter, the charges are referred to as “accumulated charges”). The accumulated charge is read out to a shift register (not shown) by a read gate pulse, and is sequentially read out as a voltage signal by a register transfer pulse.

Since the digital camera 10 generally has an electronic shutter function, a mechanical shutter such as the shutter 26 is not essential. In order to realize the electronic shutter function, the CCD 30 is provided with a shutter drain via a shutter gate. When the shutter gate is driven, accumulated charges are swept out to the shutter drain. By controlling the shutter gate, the time for accumulating the electric charges in each sensor element, that is, the shutter speed can be controlled.

A voltage signal output from the CCD 30, that is, an analog signal is color-separated into R, G, and B components by an image signal processing unit 32, and the white balance is adjusted first.
Subsequently, the imaging signal processing unit 32 performs gamma correction, sequentially A / D converts the R, G, and B signals at necessary timing, and obtains digital image data (hereinafter, simply referred to as “digital image data”) obtained as a result. ) Is output to the processing unit 60.

The imaging unit 20 further includes a finder 3
4 and a strobe 36. The finder 34 may be equipped with an LCD (not shown). In this case, various information from the main CPU 62 and the like described later can be displayed in the finder 34. The strobe 36 functions by emitting light when energy stored in a capacitor (not shown) is supplied to the discharge tube 36a.

The image pickup unit 20 further has a zoom drive section 42, a focus drive section 44, an aperture drive section 46, a shutter drive section 48, an image pickup system CPU 50 for controlling them, a distance measuring sensor 52, and a photometric sensor 54. The driving units such as the zoom driving unit 42 each have a driving unit such as a stepping motor. Release switch 114 described later
When the button is pressed, the distance measurement sensor 52 measures the distance to the subject, and the photometry sensor 54 measures the brightness of the subject. The measured distance data (hereinafter simply referred to as “distance measurement data”) and the subject luminance data (hereinafter simply referred to as “photometry data”) are sent to the imaging system CPU 50. Imaging system CPU 50
Controls the zoom drive unit 42 and the focus drive unit 44 to adjust the zoom magnification and focus of the photographing lens 22 based on the photographing information such as the zoom magnification designated by the user.

The image pickup system CPU 50 controls the R of one image frame.
The aperture value and the shutter speed are determined based on the integrated value of the digital signal of GB, that is, the AE information. According to the determined values, the aperture driving unit 46 and the shutter driving unit 48 adjust the aperture amount and open and close the shutter 26, respectively.

The imaging system CPU 50 controls the light emission of the strobe 36 based on the photometric data, and at the same time adjusts the aperture of the aperture 26. When the user instructs the capture of an image, the CCD 30 starts to accumulate electric charges, and the accumulated electric charges are output to the imaging signal processing unit 32 after a lapse of a shutter time calculated from the photometric data.

The processing unit 60 includes the digital camera 10
Overall control of the whole. The processing unit 60 includes a main CPU 62 that controls the entire digital camera 10, particularly the processing unit 60 itself, and a memory control unit 64, a YC processing unit 70, an optional device control unit 74, a compression / decompression processing unit 78, It has an I / F section 80. The main CPU 62 exchanges necessary information with the imaging system CPU 50 by serial communication or the like. The operation clock of the main CPU 62 is a clock generator 88.
Given by The clock generator 88 is an imaging system CPU
50, a clock having a different frequency is also provided to the display unit 100.

The main CPU 62 is provided with a character generator 84 and a timer 86. The timer 86 is backed up by the battery 220 and always counts the date and time. From this count value, information about the shooting date and time and other time information are given to the main CPU 62. The character generation unit 84 generates character information such as a shooting date and time and a title, and the character information is appropriately combined with the captured image. The voltage monitoring process characteristic of this embodiment is also performed by the main CPU 6.
2 done. Details will be described later with reference to FIG.

The memory control unit 64 includes a nonvolatile memory 66
And the main memory 68. Non-volatile memory 66
Is constituted by an EEPROM (electrically erasable and programmable ROM) or a flash memory, and stores data to be retained even when the power of the digital camera 10 is off, such as setting information by a user and adjustment values at the time of shipment. ing. The non-volatile memory 66 may have a main CP
A boot program or a system program of U62 may be stored. On the other hand, the main memory 68 generally has a D
It is composed of a relatively inexpensive and large-capacity memory such as a RAM. The main memory 68 has a function as a frame memory for storing data output from the imaging unit 20, a function as a system memory for loading various programs, and a function as a work area. The non-volatile memory 66 and the main memory 68
Data is exchanged with each unit inside and outside the unit 0 via the main bus 82.

The YC processing unit 70 performs YC conversion on the digital image data, and outputs a luminance signal Y and a color difference (chroma) signal B-
Generate Y, RY. The luminance signal and the color difference signal are temporarily stored in the main memory 68 by the memory control unit 64.
The compression / decompression processing unit 78 sequentially reads out the luminance signal and the color difference signal from the main memory 68 and compresses them. The data thus compressed (hereinafter simply referred to as “compressed data”) is written to a memory card, which is a type of the optional device 76, via the optional device control section 74.

The processing unit 60 further includes an encoder 72
With. The encoder 72 receives a luminance signal and a color difference signal, converts them into a video signal (NTSC or PAL signal), and outputs the video signal from a video output terminal 90. When a video signal is generated from data recorded in the optional device 76, the data is first supplied to the compression / decompression processing unit 78 via the optional device control unit 74. Subsequently, the data subjected to the necessary expansion processing by the compression / expansion processing unit 78 is converted into a video signal by the encoder 72.

The optional device control unit 74 generates a necessary signal between the main bus 82 and the optional device 76, performs logical conversion, or converts voltage according to the signal specifications recognized by the optional device 76 and the bus specifications of the main bus 82. And so on. The digital camera 10 may include, for example, a PCM as an optional device 76 in addition to the above-described memory card.
A standard CIA-compliant standard I / O card may be supported. In that case, the optional device control unit 74
It may be constituted by an IA bus control LSI or the like.

The communication I / F unit 80 is provided for the digital camera 10
Communication specifications supported by, for example, USB, RS-23
It performs control such as protocol conversion according to specifications such as 2C and Ethernet. The communication I / F unit 80 includes a driver IC as necessary, and communicates with an external device including a network via a connector 92. In addition to such standard specifications, data may be exchanged with an external device such as a printer, a karaoke machine, a game machine, or the like by a unique I / F.

The display unit 100 includes an LCD monitor 10
2 and an LCD panel 104. These are the LCD driver monitor driver 106, panel driver 10
8 respectively. LCD monitor 102
Is provided on the back of the camera with a size of, for example, about 2 inches, and displays a current shooting and playback mode, a zoom ratio for shooting and playback, a remaining battery level, a date and time, a screen for mode setting, a subject image, and the like. . The LCD panel 104 is, for example, a small black-and-white LCD provided on the upper surface of the camera and has an image quality (FINE).
/ NORMAL / BASIC etc.), information such as strobe light emission / non-light emission, standard number of recordable images, number of pixels, battery capacity, etc. are simply displayed.

The operation unit 110 includes mechanisms and electrical members necessary for the user to set or instruct the operation and the mode of the digital camera 10. The power switch 112 determines whether the power of the digital camera 10 is turned on or off. The release switch 114 has a two-stage pressing structure of half pressing and full pressing. As an example, AF and AE are locked by a half-press, captured images are captured by a full-press, and are recorded in the main memory 68, the optional device 76, etc. after necessary signal processing, data compression, and the like. The operation unit 110 may receive a setting using a rotary mode dial, a cross key, or the like in addition to these switches, and these are collectively referred to as a function setting unit 116 in FIG. Examples of operations or functions that can be specified by the operation unit 110 include “file format”, “special effects”, “printing”, “determine / save”, and “display switching”. The zoom switch 118 determines a zoom magnification.

The audio unit 200 has an audio data decoder 210, a sound source 212, an audio output terminal 214, and a speaker 216. Audio data decoder 21
0 converts audio data input from the optional device 76 via the main bus 82 into an audio signal. Sound source section 21
2 receives an audio signal from the audio data decoder 210 and converts the audio signal from digital to analog. The analog signal output from the audio data decoder 212 is
The signal is output to the outside via the audio output terminal 214 or output from the speaker 216. The audio data may be written in a data format such as MP3 or MIDI together with an image on a memory card, which is a type of the optional device 76. The audio data may also be input from the connector 92 via the main bus 82.

The digital camera 10 further includes a battery 220
And an A / D converter 222. The battery 220 supplies power to the entire digital camera 10. A / D converter 2
Reference numeral 22 converts the battery voltage of the battery 220 into a digital signal. The battery voltage converted into a digital signal is monitored by a voltage monitoring device described later.

The main operation of the above configuration is as follows.

First, the power switch 112 of the digital camera 10 is turned on, and power is supplied to each part of the camera. The main CPU 62 reads the state of the function setting unit 116 to determine whether the digital camera 10 is in the camera mode or the audio mode. The camera mode is a mode for taking an image or displaying the taken image on the LCD monitor 102, and the audio mode is a mode for outputting a sound.

When the camera is in the camera mode and performs photographing, the main CPU 62 monitors the half-pressed state of the release switch 114. When the half-pressed state is detected, the main CPU 62 obtains photometry data and distance measurement data from the photometry sensor 54 and the distance measurement sensor 52, respectively. The imaging control unit 40 operates based on the obtained data, and the focus, aperture, and the like of the photographing lens 22 are adjusted. When the adjustment is completed, characters such as “Standby” are displayed on the LCD monitor 102 to inform the user of the completion, and then the release switch 114 is monitored for a fully pressed state. When the release switch 114 is fully pressed, the shutter 26 is closed after a predetermined shutter time, and the charge stored in the CCD 30 is swept out to the image signal processing unit 32. The digital image data generated as a result of the processing by the imaging signal processing unit 32 is output to the main bus 82. The digital image data is temporarily stored in the main memory 68, thereafter processed by the YC processing unit 70 and the compression / decompression processing unit 78, and recorded in the optional device 76 via the optional device control unit 74. The recorded image is displayed on the LCD monitor 102 for a while in a frozen state, so that the user can know the captured image. Thus, a series of photographing operations is completed.

When the digital camera 10 is in the playback mode,
The main CPU 62 reads the last captured image from the main memory 68 via the memory control unit 64 and displays this on the LCD monitor 102 of the display unit 100.
When the user instructs “forward” or “reverse” in the function setting section 116 in this state, images taken before and after the currently displayed image are read out, and the LCD monitor 1
02 is displayed.

[0043] Digital camera 10 is in audio mode
In this case, the main CPU 62
The voice data is read out, and is read out from the audio unit 200.
Output from the audio output terminal 214 of the
16 to output.

FIG. 3 shows a discharge curve 502 of the battery 220 when the digital camera 10 operates in the camera mode and a discharge curve 500 of the battery 220 when the digital camera 10 operates in the audio mode. Battery 2 in camera mode
The camera alarm voltage (V _A1 ), which is the lowest voltage that can supply power from the battery 20, and the audio alarm voltage (V _A2 ), which is the lowest voltage that can supply power from the battery 220 in the audio mode, are set. In the camera mode, the battery 220
0, supply power to the processing unit 60, the display unit 100, and the operation unit 110. Since the operation of these units places a relatively heavy load on the battery 220, the battery voltage during photographing is relatively large. In the audio mode, the battery 220 stores the audio unit 200
Supply power to In the operation of the audio unit 200, the load on the battery 220 is relatively light. Therefore, as shown in FIG. 3, the battery voltage becomes higher in the audio mode than in the camera mode, and the power is constantly supplied.

For example, when switching from the camera mode to the audio mode, the load on the battery 220 is reduced, and the battery voltage is increased. In the camera mode, the battery voltage higher than the camera alarm voltage (V _A1 ) is set to the audio alarm voltage (V) in the audio mode.
_A2 ) corresponds to a higher battery voltage.

On the other hand, when switching from the audio mode to the camera mode, the load on the battery 220 becomes heavy, and the battery voltage decreases. Even if the battery voltage is higher than the audio alarm voltage (V _A2 ) in the audio mode, there is a case where the battery voltage becomes lower than the camera alarm voltage (V _A1 ) when shifting to the camera mode. Therefore, it defined as switching換許not voltage (V _A21) for the battery voltage in the audio mode whether to permit switching from the audio mode to the camera mode. The switching permission / prohibition voltage (V _A21 ) is a battery voltage in the audio mode in which the battery voltage shifts to the camera alarm voltage (V _A1 ) when the switching from the audio mode to the camera mode occurs. That is, switching from the audio mode to the camera mode is determined based on whether the battery voltage is higher than the switching permission / prohibition voltage (V _A21 ).

FIG. 4 is a functional block diagram of the voltage monitoring unit 300. The voltage monitoring unit 300 is a unit that integrates functions for monitoring a voltage. A series of operations of the voltage monitoring unit 300 is mainly performed by the main CPU 62.
And the program stored in the non-volatile memory 66 cooperates. However, the voltage monitoring unit 300 may be realized by other components, and its design flexibility is high.

The voltage monitoring unit 300 includes a mode determination section 310, a comparison voltage selection section 312, and a minimum voltage comparison section 314.
An alarm processing section 316; a mode switching section 318; a battery voltage detection section 320; a camera alarm voltage storage section 330; an audio alarm voltage storage section 332; a switching permission / prohibition voltage comparing section 334;

The mode determination unit 310 is a digital camera 1
The operation mode of the digital camera 10 is monitored to determine whether the digital camera 10 is currently in the camera mode or the audio mode, and mode information indicating which mode the digital camera 10 is in is output to the comparison voltage selection unit 312. Mode determination unit 31
In addition, when the mode is switched by the operation unit 110, the mode switching unit 0 detects a mode switching request and outputs it to the alarm processing unit 316.

The comparison voltage selection unit 312 includes the mode determination unit 3
10, and selects one of the camera alarm voltage stored in the camera alarm voltage storage unit 330 and the audio alarm voltage stored in the audio alarm voltage storage unit 332 based on the mode information, and Output to the voltage comparison unit 314. In another embodiment, the voltage monitoring unit 300 does not include the camera alarm voltage storage unit 330 and the audio alarm voltage storage unit 332 that store the camera alarm voltage and the audio alarm voltage, respectively. The camera alarm voltage and the audio alarm voltage may be inputted from outside such as the optional device 76.

Thus, the voltage monitoring unit 300
Can monitor the voltage using the alarm voltage according to the set mode.

The battery voltage detector 320 detects the battery voltage by, for example, polling of software. That is, the battery voltage detection unit 320 converts the battery voltage from an analog signal to a digital signal at regular intervals, and outputs the converted signal to the lowest voltage comparison unit 314 and the switching permission / refusal voltage comparison unit 334. As described above, since the battery voltage is detected by the software polling, the voltage can be monitored at a constant cycle.

The lowest voltage comparing section 314 determines whether one of the camera alarm voltage and the audio alarm voltage received from the comparison voltage selecting section 312 and the battery voltage detecting section 32
Compare with the current battery voltage received from 0. The lowest voltage comparing section 314 outputs to the alarm processing section 316 mode voltage information indicating whether or not the battery voltage is higher than the voltage received from the lowest voltage comparing section 314.

The switching permission / refusal voltage comparing section 334 compares the current battery voltage received from the battery voltage detecting section 320 with the switching permission / prohibition voltage stored in the switching permission / prohibition voltage storage section 336. When receiving the instruction information from the alarm processing unit 316,
Switching permission / refusal voltage comparison section 334 outputs switching voltage information indicating whether or not the current battery voltage is higher than the switching permission / prohibition voltage to alarm processing section 316. As another embodiment, the voltage monitoring unit 300 does not include the switching permission / rejection voltage storage unit 336, and in this case, the switching permission / rejection voltage comparison unit 334 may input the switching permission / rejection voltage from the outside such as the optional device 76.

The alarm processing section 316 receives the mode voltage information from the lowest voltage comparing section 314 and receives the switching voltage information from the switching permission / prohibition voltage comparing section 334. The alarm processing unit 316 causes the audio unit 200 to generate an alarm sound based on the mode voltage information and the switching voltage information. The alarm sound may be output to the outside through the speaker 216 or the earphone. The alarm processing unit 316 also receives a switching request from the mode determination unit 310, and outputs mode switching information indicating permission or prohibition of mode switching to the mode switching unit 318 based on the switching request.

The mode switching unit 318 includes the alarm processing unit 3
Mode switching information is received from 16 and mode switching is controlled based on the received information.

FIG. 5 is a flowchart showing the operation of the voltage monitoring unit 300 when the camera mode is set. When the voltage monitoring operation by the voltage monitoring unit 300 starts, the comparison voltage selection unit 312 inputs the camera alarm voltage from the camera alarm voltage storage unit 330 and sends it to the lowest voltage comparison unit 314 (S102). Next, the battery voltage detector 320 detects the battery voltage and sends it to the lowest voltage comparator 314 (S104). The battery voltage is detected by
This may be performed by software polling. In that case, the battery voltage detection unit 320 may detect the battery voltage at regular intervals. The minimum voltage comparison unit 314 compares the battery voltage with the camera alarm voltage (S106). If the battery voltage is higher than the camera alarm voltage (S10
8) Return to S104, and continue the voltage monitoring operation in S104 and S106.

If the voltage of the battery 220 is lower than the camera alarm voltage (S108), the audio unit 2
00 makes preparations for generating an alarm sound (S11).
0). For example, when power is not supplied to the audio unit 200, power is supplied from the battery 220 to the audio unit 200. Audio unit 200
If power is supplied to the power supply and the preparation for generating an alarm sound is completed, the process proceeds to S112. Next, the audio unit 200 generates an alarm sound (S1).
12). Thus, the voltage monitoring operation in the camera mode ends. As described above, since the alarm sound is generated when the battery voltage becomes lower than the camera alarm voltage, the operator can hear the alarm sound and know that the capacity of the battery 220 is small.

FIG. 6 is a flowchart showing the operation of the voltage monitoring unit 300 when the audio mode is set. Overall flowchart (S132 to S140)
Is basically the same as the operation described with reference to FIG. S13
At 2, the audio alarm voltage is selected, and at S136, the battery voltage is compared with the audio alarm voltage. In this point, the operation of the voltage monitoring unit 300 when the audio mode is set in FIG. 6 is different from the operation of the voltage monitoring unit 300 when the camera mode is set in FIG. Further, in the audio mode, since preparation for generating an alarm sound is completed, a step corresponding to the alarm sound generation preparation step (S110) in FIG. 5 may not be provided.

FIG. 7 is a flowchart showing the operation of the voltage monitoring unit 300 when the mode is switched.
The operation of the voltage monitoring unit 300 starts, and the mode determination unit 310 determines whether there is a switching request. When a switching request is detected (S200), a request for switching to the audio mode in the camera mode (S20).
2) The alarm processing unit 316 sends a switching instruction to the mode switching unit 318. The mode switching unit 318 switches from the camera mode to the audio mode based on the switching instruction (S204). As described above, the voltage monitoring unit 3 when the audio mode is selected in the camera mode
The operation of 00 ends.

As described above, when the mode of the digital camera 10 is switched from the camera mode to the audio mode,
The comparison voltage selection unit 312 automatically switches the alarm voltage from the camera alarm voltage to the audio alarm voltage. Therefore, the alarm voltage and the battery voltage according to the mode can be compared.

In S202, if the request is for switching to the camera mode in the audio mode, the alarm processing unit 3
16 instructs the switching permission / refusal voltage comparison unit 334 to output the switching voltage information to the alarm processing unit 316, and inputs the switching voltage information from the switching permission / refusal voltage comparison unit 334 (S210). When the battery voltage is higher than the switching permission / prohibition voltage (S212), the alarm processing unit 316 sends a switching instruction to the mode switching unit 318. Mode switching unit 31
8 switches from the audio mode to the camera mode based on the switching instruction. (S214). Thus, the operation of the voltage monitoring unit 300 when the camera mode is selected in the audio mode ends.

If the voltage of the battery 220 is lower than the switching permission / prohibition voltage in S212, the audio unit 200
An alarm sound is generated (S230). Next, the alarm processing unit 316 sends a switching prohibition instruction to the mode switching unit 318 to prohibit switching to the camera mode (S2).
32). Thus, the operation of the voltage monitoring unit 300 ends.

As described above, when the camera mode in which the load is relatively heavy is selected in the audio mode in which the load on the battery 220 is relatively light, the battery voltage in the audio mode is compared with the switching permission voltage to determine whether switching is permitted. Therefore, when the camera mode is set, it is possible to prevent the camera mode from being set when the battery voltage is lower than the camera alarm voltage.

In the second embodiment, when the battery voltage is lower than the camera alarm voltage in S108 of FIG. 5 showing the flowchart of the voltage monitoring unit 300 in the first embodiment, an alarm sound is generated (S110).
Then, the mode is automatically switched from the camera mode to the audio mode. In this point, the present embodiment is different from the first embodiment. In this case, the mode is switched to the audio mode, and the process jumps to the audio alarm voltage selection step (S132) in FIG. 6 of the first embodiment. The other detailed operation of the voltage monitoring unit 300 in the present embodiment is the same as the detailed operation of the voltage monitoring unit 300 in the first embodiment described with reference to FIGS. Further, the overall configuration of the digital camera 10 and the function of the voltage monitoring unit 300 in the present embodiment are the same as the overall configuration of the digital camera 10 and the function of the voltage monitoring unit 300 described with reference to FIGS. 2 and 3 in the first embodiment. Is the same as

As described above, when the battery voltage becomes lower than the camera alarm voltage in the camera mode, the audio mode is switched to the audio mode which can operate with the battery voltage lower than the camera alarm voltage without waiting for the mode switching by the operator. be able to.

As described above, according to the above-described embodiment, when the battery voltage falls below the voltage at which the digital camera 10 can operate sufficiently in the audio mode and the camera mode, an alarm sound is generated. You can know that it is slight.

According to the above embodiment, when the audio mode is selected in the camera mode, the comparison voltage selection unit 312 automatically switches the alarm voltage from the camera alarm voltage to the audio alarm voltage. The voltage can be set.

According to the above-described embodiment, when the camera mode having a larger load than the audio mode is selected in the audio mode, it is possible to determine whether switching is possible by comparing the battery voltage with the switching permission voltage.

Although the present invention has been described with reference to the embodiment, the technical scope of the present invention is not limited to the scope described in the above embodiment. Various changes or improvements can be added to the above embodiment.

In a first modification, instead of the camera mode and the audio mode, a photographing mode for photographing an image,
It may be a voltage monitoring device in a reproduction mode for reproducing an image, or may be a combination of any other modes.

In the second modification, two alarm voltages are set in the first and second embodiments. However, three or more alarm voltages may be used.

In the third modification, in the camera mode of the digital camera 10, the audio unit may be off or on. That is, two modes may be provided when the audio unit is on.

A fourth modification is that, in this embodiment,
The sound is generated as the alarm processing. Alternatively, for example, the LED may blink or light, or a warning character may be displayed on the LCD monitor 102 or the LCD panel 104, for example. Further, the alarm processing may be an arbitrary combination of these.

In the fifth modification, the first and second embodiments have been described using the digital camera 10. However, any battery drive device other than the digital camera 10 may be used.

In the sixth modification, in the present embodiment, there are two alarm voltage values provided corresponding to the modes, but instead of these, the supply of power is stopped.
There may be two voltage values.

It is apparent from the description of the appended claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

[0078]

As is apparent from the above description, according to the present invention, a more appropriate warning is issued according to the status of the device.
be able to.

[Brief description of the drawings]

FIG. 1 is a diagram showing a general discharge curve when a battery power supply is used.

FIG. 2 is a configuration diagram of a digital camera 10 operable with a battery power supply according to the embodiment.

FIG. 3 is a diagram showing a discharge curve of a battery 220 when the digital camera 10 operates in a camera mode and an audio mode.

FIG. 4 is a functional block diagram of the voltage monitoring unit 300.

FIG. 5 is a flowchart illustrating an operation of the voltage monitoring unit 300 when the camera mode is set.

FIG. 6 is a flowchart showing an operation of the voltage monitoring unit 300 when the audio mode is set.

FIG. 7 is a flowchart showing an operation of the voltage monitoring unit 300 when the mode of the digital camera 10 is switched.

[Explanation of symbols]

Reference Signs List 10 digital camera 20 imaging unit 60 processing unit 62 main CPU 68 main memory 74 optional device control unit 76 optional device 110 operation unit 112 power switch 114 release switch 116 function setting unit 118 zoom switch 200 audio unit 210 audio data decoder 212 sound source unit 214 Audio output terminal 216 Speaker 220 Battery 222 A / D conversion unit 310 Mode determination unit 312 Comparison voltage selection unit 314 Minimum voltage comparison unit 316 Alarm processing unit 318 Mode switching unit 330 Camera alarm voltage storage unit 332 Audio alarm voltage storage unit 334 Switching permission / prohibition Voltage comparison unit 336 Switching permission / rejection voltage storage unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/00 302 H02J 7/00 302D 5G003 H04N 5/225 H04N 5/225 F 5H030 A F term (reference) 2G016 CA04 CB11 CB12 CC01 CC04 CC06 CC27 CE00 2G035 AA19 AA21 AB03 AC01 AC17 AD23 AD26 AD28 AD45 AD64 2H054 AA01 2H100 DD02 5C022 AA13 AB15 AB22 AB40 AB66 AC03 AC12 AC32 AC42 AC54 AC56 AC69 AC71 AC07 5GA003 DA01 BA03 DA03 DA01

Claims (11)

[Claims] 1. An apparatus for monitoring a battery voltage in a power supply of a portable device having at least a first mode and a second mode, wherein in the case of the first mode, a device provided corresponding to the first mode. 1. In the case of the second mode, a second predetermined voltage different from the first predetermined voltage provided corresponding to the second mode is selected and output. A comparison voltage selection unit, a lowest voltage comparison unit that compares the battery voltage with a predetermined voltage value output from the comparison voltage selection unit, and wherein the battery voltage is higher than a voltage value output from the comparison voltage selection unit. A voltage monitoring device comprising: an alarm processing unit that performs predetermined alarm processing when it is determined that the voltage is low. 2. The portable device further includes first and second electric circuits, wherein the first mode is a mode in which power is to be supplied from the power supply to the first electric circuit, and Two modes are
A mode in which power is to be supplied from the power supply to the second electric circuit, wherein the first predetermined voltage is a lower limit of the battery voltage that permits supply of power from the power supply to the first electric circuit. 2. The voltage according to claim 1, wherein the second predetermined voltage is a lower limit of the battery voltage that permits supply of power from the power supply to the second electric circuit. 3. Monitoring device. 3. When the first mode is a mode in which a load on the power supply is lighter than that in the second mode, the alarm processing unit sets the battery voltage to the first mode in the first mode. The voltage monitoring device according to claim 1, wherein when the voltage becomes lower than a predetermined voltage, the mode can be switched to the second mode. 4. A mode determining unit for detecting a request to switch from the second mode to the first mode when the first mode is a mode in which a load on the power supply is lighter than the second mode. A switching permission / rejection voltage comparison unit that compares the battery voltage with a switching permission / rejection voltage that determines whether or not the switching from the second mode to the first mode is possible with respect to the battery voltage in the second mode; 4. The voltage monitoring device according to claim 2, wherein when the switching request is detected, the comparison result of the switching permission / refusal voltage comparison unit is checked. 5. The switching permission / prohibition voltage is set in the second mode such that if the switching from the second mode to the first mode occurs, the battery voltage shifts to the first predetermined voltage. The voltage monitoring device according to claim 4, wherein the voltage monitoring device is a battery voltage. 6. The alarm processing unit according to claim 4, wherein switching to the first mode is prohibited when the battery voltage is lower than the switching permission / prohibition voltage in the second mode. 6. The voltage monitoring device according to 5. 7. The voltage monitoring apparatus according to claim 1, wherein the alarm processing unit instructs output of an alarm sound as the alarm processing. 8. A digital camera operable with a battery power supply, comprising: a processing unit that controls the operation of the digital camera overall, wherein the processing unit monitors the battery voltage of the power supply. The voltage monitoring device comprises: a first mode in which the power supply should supply power to a first electric circuit of the digital camera; and the power supply supplying power to a second electric circuit of the digital camera. A mode determining unit that determines which mode of the second mode to be selected; and, in the case of the first mode, the battery voltage that permits supply of power from the power supply to the first electric circuit. The first alarm voltage, which is the lower limit value, is selected and output, and the second
In the case of the mode, a comparison voltage selection unit that selects and outputs a second alarm voltage that is a lower limit value of the battery voltage that permits supply of power from the power supply to the second electric circuit; A lowest voltage comparison unit that compares the value output from the comparison voltage selection unit; and an alarm that performs a predetermined alarm process when the battery voltage is determined to be lower than the value output from the comparison voltage selection unit. A digital camera, comprising: a processing unit. 9. The image forming apparatus according to claim 1, wherein the first electric circuit is an image pickup unit that picks up an image, and the second electric circuit is an audio unit that outputs sound according to an instruction from the processing unit. The digital camera according to claim 8. 10. The digital camera according to claim 9, wherein the alarm processing unit instructs the audio unit to output an alarm sound. 11. A method for monitoring a battery voltage in a power supply of a portable device having at least a first mode and a second mode, wherein, in the case of the first mode, a second terminal provided corresponding to the first mode. Selecting one alarm voltage and, in the case of the second mode, selecting a second alarm voltage provided corresponding to the second mode; and selecting the battery voltage and the alarm voltage selected by the selecting step. And a warning step of performing a predetermined alarm process when the battery voltage is lower than the value of the alarm voltage selected in the selection step.