JP2004087171A - Portable device - Google Patents

Abstract

A portable device that can be stably driven for a long time is provided.
Each circuit of a digital camera operates with electric power generated by a fuel cell. The electric energy generated by the fuel cell 30 is accumulated in the buffer 72 via the converter 70 and further accumulated in the buffer 76 via the converter 74. The converter 74 has a function of blocking the buffer 72 and the buffer 76. When the charge level of the buffer 76 becomes equal to or lower than the predetermined level V2, the buffer 76 is charged with the electric energy charged in the buffer 72. When a large load occurs, the converter 74 blocks between the buffer 72 and the buffer 76 in order to prevent the current from the buffer 76 from flowing back to the buffer 72.
[Selection] Figure 3

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital camera, and more particularly to a portable device that operates with electric power generated by a fuel cell.
[0002]
[Prior art]
Conventionally, a technique has been proposed in which electric power generated by a solar battery is stored in a secondary battery, and a camera is driven by the electric power stored in the secondary battery (see, for example, JP-A-6-163965).
[0003]
According to this invention, the solar cell unit detachably attached to the camera is provided with a connecting groove in the camera-side solar cell unit and the additional solar cell unit so that the additional solar cell unit can be attached and detached, The solar cell unit can be rotated with respect to the camera. Thereby, a solar cell unit can be easily turned to the light source direction, and the electric power generated by the solar cell can be efficiently charged to the secondary battery.
[0004]
However, the above-described conventional technique has a problem that since it uses a solar cell, it cannot be charged at night and cannot be used stably for a long time.
[0005]
In addition, a technique using a fuel cell as a power source of the apparatus has been proposed (see, for example, Japanese Patent Laid-Open Nos. 2002-134154, 2002-49440, and 10-64567).
[0006]
[Problems to be solved by the invention]
The fuel cell, for example, generates electric energy by chemically reacting a fuel such as methanol water or hydrogen. However, in the above-described prior art, the power generation control of the fuel cell is not disclosed in detail. There has been a problem that stable driving may not be possible when the load level suddenly increases, that is, when large electric power is required instantaneously.
[0007]
The present invention has been made to solve the above-described problems, and an object thereof is to provide a portable device that can be stably driven for a long time.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a fuel cell that generates electric energy by chemically reacting the supplied fuel, and the electric energy generated by the fuel cell is charged and charged. And charging means for supplying electric energy to each part of the apparatus, and control means for controlling power generation by the fuel cell and charging by the charging means in accordance with a load level of the apparatus.
[0009]
According to the present invention, the fuel cell is provided that generates electric energy by chemically reacting the supplied fuel, and the portable device is operated by the electric energy generated by the fuel cell. Examples of portable devices to which the present invention is applied include portable terminal devices such as digital cameras and cellular phones.
[0010]
The electric energy generated by the fuel cell is once charged in the charging means. Then, the electric energy charged in the charging means is supplied to each part of the apparatus. As the charging means, for example, a secondary battery such as a lithium ion battery, a high-capacity capacitor, or the like can be used. As described above, each part of the apparatus can be operated by the electric energy charged in the charging means, so that when the load level of the apparatus suddenly increases, that is, when a large amount of electric power is required instantaneously or the fuel cell Even when the power generation by is unstable, the apparatus can be operated stably for a long time compared to the case where the electric energy generated by the fuel cell is directly supplied to each part of the apparatus.
[0011]
The control means controls power generation by the fuel cell and charging by the charging means according to the load level of the apparatus. Here, the load level corresponds to a physical quantity (for example, current amount) related to power consumed by the operation of the apparatus, and differs depending on the type of operation of the apparatus. Therefore, the control unit controls the power generation by the fuel cell and the charging by the charging unit according to the type of operation selected by the user operating the portable device, for example. Further, the amount of current supplied from the charging means to each part of the apparatus may be detected, and the power generation by the fuel cell and the charging by the charging means may be controlled based on the amount of current.
[0012]
By the way, for example, when a large load is applied instantaneously, such as when a flash device is taken when the portable device is a digital camera, the current from the charging means flows backward to the fuel cell side, and the fuel cell is damaged. There is a risk of doing.
[0013]
Therefore, as described in claim 2, the apparatus further includes a blocking unit that blocks between the charging unit and the fuel cell, and the control unit has a load level of the device equal to or higher than a predetermined level. In this case, it is preferable to stop the power generation of the fuel cell and to control the shut-off means so that the charging means and the fuel cell are shut off.
[0014]
As a result, even when a large load is instantaneously applied, the current from the charging means can be prevented from flowing back to the fuel cell side, and the fuel cell can be protected.
[0015]
According to a third aspect of the present invention, the charging means charges the electric energy charged in the first buffer and the first buffer that charges the electric energy generated by the fuel cell, and It is good also as a structure further comprised with the 2nd buffer which supplies the charged electrical energy to each part of an apparatus, and also provided the interruption | blocking means which interrupts | blocks between the said 1st buffer and the said 2nd buffer.
[0016]
In this case, even when a large load is generated instantaneously, there is no influence between the fuel cell and the first buffer, so there is no need to stop the power generation of the fuel cell. Therefore, charging from the fuel cell to the first buffer can be continued and charging can be performed efficiently.
[0017]
According to a fourth aspect of the present invention, the control means charges the first buffer when the level of electrical energy charged in the second buffer is equal to or lower than a predetermined level. And controlling the electric energy so that the second buffer is charged at a predetermined supply level determined in advance, and the level of the electric energy charged in the second buffer is lower than the predetermined level. In this case, control may be performed so that the electric energy charged in the first buffer is charged in the second buffer at a high supply level higher than the predetermined supply level.
[0018]
As a result, even when a large load is generated and the electrical energy charged in the second buffer is reduced, the second buffer is charged by the electrical energy charged in the first buffer. It can be driven stably.
[0019]
According to a fifth aspect of the present invention, when the electrical energy charged in the second buffer is equal to or lower than a predetermined operation restriction level lower than the quick charge level, the control means You may make it restrict | limit the predetermined operation | movement of an apparatus.
[0020]
For example, when the electric energy charged in the second buffer becomes equal to or lower than the operation limit level, an operation that cannot be operated at the charge level of the operation limit level is prohibited. Then, the prohibition is canceled when the charge level exceeds at least the operation restriction level. In addition, you may provide the alerting | reporting means to alert | report that it has fallen below the charge level operation | movement restriction | limiting level. Accordingly, the function can be reduced and the operation of the apparatus can be continued without stopping the entire apparatus, and convenience can be improved.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, a case where the present invention is applied to a digital camera will be described.
[0022]
In the digital camera 10 to which the present invention is applied, as shown in FIGS. 1A and 1B, the main body 12 is substantially box-shaped, and the main body 12 can be easily gripped on the left side when viewed from the front. A grip 13 is formed.
[0023]
As shown in FIG. 1A, on the front side of the main body 12, a shooting lens 14, a finder 16 for visually confirming a shooting range, etc., for emitting illumination light in the case of shooting at low illuminance, etc. A flash device 18 is attached.
[0024]
A slot 22 into which an image storage memory 20 as a memory card such as a smart media can be loaded is provided on the right side as viewed from the front of the main body 12. ), A mode dial 24 and a power switch 26 are provided on the left side, and a central portion of the mode dial 24 is a shutter button 28. In addition, a housing opening for a fuel cell 30 that is a power source of the digital camera 10 is provided on the bottom surface on the left side when viewed from the front of the main body 12. A heater 32 for heating the fuel cell 30 is provided around a storage box (not shown) of the fuel cell 30. Thereby, when the fuel cell 30 is set in the storage box from the storage port (not shown), the heater 32 is disposed around the fuel cell 30 as shown in FIG.
[0025]
The mode dial 24 is a dial for selecting the shooting mode of the digital camera. For example, the photographer can select the shooting status of the subject from among the auto shooting mode, macro shooting mode, landscape shooting mode, sports shooting mode, night view shooting mode, and the like. An appropriate shooting mode can be selected. The shutter button 28 is configured to perform AF processing when half-pressed, and to perform imaging processing when fully pressed.
[0026]
Further, as shown in FIG. 1B, a color image display LCD 34 comprising a reflective LCD or a transmissive front LCD is provided at the lower left of the back surface of the main body 12, and above the image display LCD 34, Various selection buttons such as a monochrome status LCD 36, a flash button 38, a cross button 40, a menu execution button 42, and zoom buttons 43T and 43W are provided.
[0027]
The image display LCD 34 is composed of a liquid crystal display panel having a screen size of, for example, 640 × 480 pixels, and displays an image on the entire screen based on the image data stored in the image storage memory 20 when there is an image display instruction. Or display a plurality of reduced images side by side (hereinafter referred to as thumbnail display) or display various function selection screens. The status LCD 36 displays the current state and settings of the digital camera, such as the operation mode, image quality, battery capacity, flash on / off, and the number of images that can be taken.
[0028]
The cross button 40 is a button for selecting a button displayed when the image display LCD 34 is displaying a screen for selecting various items, or for moving the cursor. The flash button 38 is a button for issuing a forced flash instruction when the flash device 18 forcibly emits flash light, or a flash prohibition instruction when prohibiting the flash device 18 from flashing, and the menu execution button 42 is used. The button for issuing an instruction to execute the item selected by the cross button 40 on the screen displayed on the image display LCD 34. The zoom button 43T is a button for changing the shooting angle of view to the telephoto side, and the zoom button 43W is a button for changing the shooting angle of view to the wide angle side.
[0029]
FIG. 3 shows a block diagram of the digital camera 10. The digital camera 10 includes a photographic lens 14. The photographic lens 14 is composed of a plurality of lenses including, for example, a focus lens. For example, a zoom lens capable of changing the focal length is used, but a lens having a single focal length (fixed focus) may be used. Good.
[0030]
The taking lens 14 is zoom-controlled by a zoom control unit 45. The zoom control unit 45 drives the photographing lens 14 to change the photographing field angle to the telephoto side or the wide angle side according to the operation amount of the zoom buttons 43T and 43W.
[0031]
The focus lens of the photographic lens 14 is controlled by the distance measurement control unit 46. The distance measurement control unit 46 drives the focus lens so that the subject is in focus by autofocus control described later.
[0032]
The subject image formed on the light receiving surface of the image sensor 50 including the CCD and the like via the photographing lens 14 and the shutter 48 is converted into signal charges corresponding to the amount of incident light by each sensor. The signal charge accumulated in this way is read out by a drive pulse applied from a timing signal generation circuit (TG) 52, and is sequentially output from the image sensor 50 as a voltage signal (analog image signal) corresponding to the signal charge. .
[0033]
A shutter 48 is provided in front of the image sensor 50. The shutter 48 is controlled by the exposure control unit 54 and opens and closes at a set shutter speed.
[0034]
The image sensor 50 may be provided with an electronic shutter function and the shutter 48 may be omitted. In this case, the image pickup device 50 is provided with a shutter drain via a shutter gate and controlled by the exposure control unit 54, and drives the shutter gate with a shutter gate pulse to sweep out accumulated signal charges to the shutter drain. it can. That is, the image sensor 50 controls the accumulation time (shutter speed) of charges accumulated in each sensor by the shutter gate pulse.
[0035]
The signal read from the image sensor 50 is subjected to predetermined processing by the signal processing circuit 56. The signal processing circuit 56 includes, for example, a CDS circuit and an A / D converter (not shown). The CDS circuit performs correlated double sampling (CDS) processing on the image signal from the image sensor 50, color separation processing for each of the R, G, and B color signals, and adjustment of the signal level of each color signal (pre-white balance processing). I do. The image signal that has undergone these predetermined analog signal processes is converted into R, G, and B digital signals by an A / D converter and then output to the image processor 58.
[0036]
The timing signal generation circuit 52 provides appropriate timing signals to the image sensor 50 and the signal processing circuit 56 in response to a command from the image processor 58, and each circuit receives a timing signal applied from the timing signal generation circuit 52. Are driven in synchronization with each other.
[0037]
The image processor 58 includes circuits for performing various image processing, for example, an integration circuit, a gain adjustment circuit, a gamma correction circuit, a luminance / color difference signal processing circuit (YC processing circuit), a compression / decompression circuit, and an image storage memory. 20 card interfaces, a display driver for driving the image display LCD 34, and the like.
[0038]
The image processor 58 is connected to a high-speed calculation memory 60 as a work memory for performing image processing at high speed, an image storage memory 20, an external communication interface 62, and an image display LCD 34. The external communication interface is an interface for exchanging image data and the like with an external device such as a personal computer. For example, an interface such as USB (Universal Serial Bus) or IEEE1394 can be used.
[0039]
The data output from the A / D converter of the signal processing circuit 56 is stored in the high-speed calculation memory 60 and added to the integrating circuit. The integration circuit divides the photographing screen into a plurality of blocks (for example, 64 blocks of 8 × 8), and performs an integration calculation of the received G signal for each block. Note that the luminance signal (Y signal) may be generated from the R, G, and B data, and the luminance signal may be integrated.
[0040]
The image processor 58 calculates the evaluation value E of the shooting screen according to a predetermined algorithm based on the integrated value information (calculation result) obtained by the integrating circuit, and uses the obtained evaluation value E to obtain the gain in the gain adjustment circuit. Determine the value (amplification factor). The image processor 58 controls the gain amount in the gain adjustment circuit according to the determined gain value.
[0041]
The R, G, B image data stored in the high-speed calculation memory 60 is amplified by a gain adjustment circuit. The amplified image data is subjected to a gamma correction process in a gamma correction circuit and then sent to a YC processing circuit, where the RGB data is converted into a luminance signal (Y signal) and a color difference signal (Cr, Cb signal). The
[0042]
The luminance / color difference signal (abbreviated as YC signal) generated in the YC processing circuit is written back to the high-speed calculation memory 60. The YC signal stored in the high-speed calculation memory 60 is supplied to a display driver, converted into a predetermined signal (for example, an NTSC color composite video signal), and output to the image display LCD 34.
[0043]
The image displayed on the image display LCD 34 becomes visible when the backlight 65 that is controlled to be turned on by the control μ computer 64 is turned on. The image display LCD 34 may be a YC signal input type or an RGB signal input type, and a driver corresponding to the display device is applied.
[0044]
Further, the image data is periodically rewritten by the image signal output from the image sensor 50, and the video signal generated from the image data is supplied to the image display LCD 34, so that the image captured by the image sensor 50 is real-time. It is displayed on the image display LCD 34 as a moving image (live image) or as a substantially continuous image, although not in real time.
[0045]
The image display LCD 34 can be used as an electronic view finder, and the photographer can check the shooting angle of view with the display image on the image display LCD 34 or the optical viewfinder 16. In response to a predetermined recording instruction (shooting start instruction) operation such as an operation of pressing the shutter button 28 included in the switch group 66, the capture of image data for recording is started.
[0046]
The image data that has been subjected to various types of image processing is compressed by a compression / decompression circuit of an image processing processor. The compression / decompression circuit compresses the YC data on the high-speed calculation memory 60 in accordance with JPEG or another predetermined format. The compressed image data is recorded in the image storage memory 20 as a memory card by the card interface.
[0047]
When the mode for recording non-compressed image data (non-compression mode) is selected, the image data is recorded in the image storage memory 20 without being compressed without performing the compression processing by the compression / decompression circuit. .
[0048]
The digital camera 10 according to the present embodiment uses an image storage memory 20 as a memory card as means for storing image data. Specifically, for example, a recording medium such as smart media is applied. The form of the recording medium is not limited to the above, and various forms such as a PC card, a micro drive, a multimedia card (MMC), a magnetic disk, an optical disk, a magneto-optical disk, and a memory stick are possible. Corresponding signal processing means and interfaces are applied.
[0049]
In the reproduction mode, the image data read from the image storage memory 20 is decompressed by the compression / decompression circuit and output to the image display LCD 34 by the display driver.
[0050]
The control μ computer 64 controls the corresponding circuit block based on the input signal from the switch group 66. For example, the zoom control unit 45, the distance measurement control unit 46, and the exposure control unit 54 are collectively controlled to control the zooming operation and the automatic focus adjustment (AF) operation of the photographing lens 14, and the control of the automatic exposure adjustment (AE). Etc.
[0051]
The exposure control unit 54 performs various calculations such as a focus evaluation calculation and an AE calculation based on the image signal output from the image sensor 50, sets the shutter speed of the shutter 48 based on the calculation, and a diaphragm (not shown). Set to a proper aperture value.
[0052]
The distance measurement control unit 46 controls a driving means (for example, an AF motor or an iris motor) (not shown) of the photographing lens 14 to move the focus lens to the in-focus position.
[0053]
For example, a contrast AF method in which the focus lens is moved so that the high frequency component of the G signal is maximized is employed for the AF control. In the AE control, the subject brightness (shooting EV) is obtained based on the integrated value obtained by integrating the R, G, and B signals of one frame, and the aperture value and the shutter speed are determined based on the taken EV. In addition to driving, the opening and closing of the shutter 48 is controlled so as to achieve the determined shutter speed. Therefore, only by directing the photographing lens 14 of the digital camera 10 toward the subject, optimal exposure adjustment is performed and focusing is automatically performed.
[0054]
At the time of shooting and recording, when the shutter button 28 is “half-pressed”, the above-mentioned photometric operation is repeated a plurality of times to obtain an accurate shooting EV, and the aperture value and shutter speed at the time of shooting are finally determined based on this shooting EV. To do. Then, when the shutter button 28 is “fully pressed”, the aperture is driven so as to achieve the finally determined aperture value, and the opening / closing of the shutter 48 is controlled so as to achieve the determined shutter speed. In addition to a method of controlling AE and AF based on an image signal acquired from the image sensor 50, a well-known photometric sensor, a distance measuring sensor including an AF light projecting / receiving sensor, or the like may be used.
[0055]
The switch group 66 includes the shutter button 28 for giving an instruction to start image recording, the mode dial 24, the power switch 26, the zoom buttons 43T and 43W, the flash button 38, the cross button 40, and other various input means. included. These input means have various forms such as switch buttons, dials, and slide-type knobs. There is also an aspect in which a setting menu or a selection item is displayed on the screen of the touch panel or the liquid crystal monitor display unit, and a desired item is selected with a cursor. . The switch group 60 may be disposed in the camera body, or may be configured as a remote control transmitter separated from the camera body.
[0056]
The digital camera 10 also includes a flash device 18. The flash device 18 has a light-receiving element for dimming, and a “low-brightness automatic light-emitting mode” in which the flash device 18 automatically strobes light when the brightness is low according to the operation of the flash button 38 included in the switch group 66. ”,“ Forced light emission mode ”in which the flash device 18 emits strobe light regardless of subject brightness, or“ light emission inhibition mode ”in which the flash device 18 inhibits strobe light emission.
[0057]
The control μ computer 64 controls charging of the main capacitor of the flash device 18 and discharge (light emission) timing to the light emitting tube (for example, xenon tube) according to the strobe mode selected by the user, and from the light receiving element. The emission stop is controlled based on the measurement result. The light receiving element receives the reflected light from the subject illuminated by the light emitted from the strobe and converts it into an electrical signal corresponding to the amount of light received. The signals of the light receiving elements are integrated by an integration circuit (not shown), and the strobe light emission is stopped when the integrated amount of received light reaches a predetermined appropriate amount of received light.
[0058]
Each of the above circuits operates with electric power generated by the fuel cell 30. The fuel cell 30 is, for example, a polymer electrolyte fuel cell, and a methanol direct fuel cell (DMFC) that directly supplies methanol water to the cell is used. As shown in FIG. 4, the fuel cell 30 has a configuration in which a proton conductive film 30C is sandwiched between an anode 30A and a cathode 30B. Then, methanol water (CH ₃ OH + H ₂ O) is supplied, and oxygen (O ₂ ) Is supplied, a chemical reaction occurs along with proton conduction, methanol is continuously oxidized to generate an electromotive force e, and carbon dioxide (CO ₂ ) And water (H ₂ O) is discharged. Electric power can be supplied to the load 68, that is, each circuit of the digital camera 10 by the electromotive force e.
[0059]
Such a methanol direct fuel cell is suitable for miniaturization because it does not require a peripheral auxiliary device such as a reformer for producing hydrogen from methanol or a reactor for controlling CO concentration. However, since the temperature required for power generation, that is, the lower limit value of the operating temperature is higher than that of other batteries, the operation of the fuel cell may be unstable particularly in an extremely cold region. For this reason, in the present embodiment, as described above, the heater 32 for heating the fuel cell 30 is provided around the storage box (not shown) of the fuel cell 30. Thereby, the fuel cell 30 can be heated and can be operated stably.
[0060]
The digital camera 10 also includes a detection mechanism (not shown) that detects that the fuel cell 30 is set in the storage box, and the control μ computer 64 detects that the fuel cell 30 has been set by this detection mechanism. Can be detected.
[0061]
As shown in FIG. 5, the electric energy generated by the fuel cell 30 is converted into a predetermined level of electric energy (voltage) by the converter 70 and accumulated in the buffer 72, and further accumulated in the buffer 72. The electric energy is converted into electric energy (voltage) of a predetermined level by the converter 74 and stored in the buffer 76. The electric energy stored in the buffer 76 is supplied to each circuit. The buffer 72 is composed of, for example, a high-capacity capacitor, and the buffer 76 is composed of, for example, a secondary battery (for example, a lithium ion battery). The converters 70 and 74 are controlled by the control μ computer 64.
[0062]
The converter 74 has a function of converting the electric energy charged in the buffer 72 into a predetermined level of electric energy, and a function of blocking between the buffer 76 and the buffer 72 in accordance with an instruction from the control μ computer 64. Yes. As a result, when a large load such as strobe light emission occurs, the current from the buffer 76 can be prevented from flowing back to the buffer 72 side, and the fuel cell 30 can be protected. Further, it is not necessary to stop the power generation by the fuel cell 30, and the buffer 72 can be continuously charged.
[0063]
The heater 32 is supplied with electric power from the buffer 76 and heats the fuel cell 30. A switch 78 for turning on / off the electric power supply to the heater 32 is provided between the heater 32 and the buffer 76. The on / off state of the switch 78 is controlled by the control μ computer 64.
[0064]
A thermometer 80 that detects the temperature of the fuel cell 30 is provided in the vicinity of the fuel cell 30. The control μ computer 64 turns the heater 78 on and off by appropriately turning on and off the switch 78 based on the temperature of the fuel cell 30 detected by the thermometer 80 to heat the fuel cell 30 and is stored in the buffer 76. The level (for example, voltage level) of electric energy is monitored, and the start and stop of power generation of the fuel cell 30 are controlled according to the load level.
[0065]
The digital camera 10 corresponds to the portable device of the present invention, the fuel cell 30 corresponds to the fuel cell of the present invention, the buffer 72 corresponds to the first buffer of the present invention, and the buffer 76 corresponds to the second of the present invention. The control μ computer 64 corresponds to the control means of the present invention.
[0066]
Next, charging control by the control μ computer 64 will be described.
[0067]
FIG. 6 shows the transition of the power of section A shown in FIG. 5, that is, the transition of the power supplied from the fuel cell 30 to the buffer 72 side, and the transition of power of section B shown in FIG. FIG. 5 shows the transition of the power supplied to the C section and the transition of the power of the section C shown in FIG. 5, that is, the transition of the power supplied from the buffer 72 to the buffer 76 side.
[0068]
As shown in FIG. 6, the control μ computer 64 determines that when the power of the B part becomes equal to or higher than a predetermined level load 2, that is, when the load level (load power) becomes equal to or higher than the predetermined level load 2. The converter 74 is controlled so that the buffer 72 and the buffer 76 are disconnected from each other. The predetermined level Load2 is set to a level at which the current may flow backward from the buffer 76 to the buffer 72, for example, when the load level exceeds this level. For example, when the flash device 18 is used for flash photography, the load level is Load2 or higher.
[0069]
As described above, when the load level is equal to or higher than the predetermined level load2, the converter 74 is controlled so that the buffer 72 and the buffer 76 are disconnected, and charging from the buffer 72 to the buffer 76 is stopped. Therefore, the current from the buffer 76 can be prevented from flowing back to the buffer 72 side, and the fuel cell 30 can be protected. As shown in FIG. 6, when the load level is less than the predetermined level load 2, the buffer 76 is charged with the electric energy accumulated in the buffer 72.
[0070]
Further, in the present embodiment, as shown in FIG. 5, two buffers are provided, and the converter 72 can block between the buffer 72 and the buffer 76, so that the power generation of the fuel cell 30 is stopped. There is no need, and as shown in FIG. 6, power can be continuously generated, and the buffer 72 can be charged with the generated electric energy. Thereby, the apparatus can be driven stably for a long time.
[0071]
Further, details of charge control by the control μ computer 64 will be described.
[0072]
As shown in FIG. 7, when power generation by the fuel cell 30 is first started (at time t1), it is necessary to store electric energy to some extent in the first-stage buffer 72. When the level of the electric energy charged in the buffer 72, that is, the charge level is less than a predetermined level th1, the converter 70 is configured so that the electric energy generated by the fuel cell 30 is charged in the buffer 72. To control.
[0073]
When the charge level is equal to or higher than a predetermined level th1 (at time t2), the converters 70 and 74 are controlled so that the electric energy generated by the fuel cell 30 is charged in the buffer 76. To do.
[0074]
When the charging level of the buffer 76 reaches a predetermined level V1 (at time t3), charging of the buffer 76 is stopped and charging of the buffer 72 is started again. At this time, the buffer 72 is charged until the predetermined level th2 is reached, but until then, the charge level of the buffer 76 begins to decrease (at time t4), and when it decreases more than a predetermined level (at time t5). Then, charging of the buffer 72 is stopped, and charging of the buffer 76 is started. Then, when the charge level of the buffer 76 becomes equal to or higher than the predetermined level V1 again (at time t6), the charging of the buffer 76 is stopped and the charging of the buffer 72 is started.
[0075]
When a relatively small load 82 is generated (time t7), the charge level of the buffer 76 starts to decrease, but the buffer 72 is continuously charged. When the charge level of the buffer 76 becomes equal to or lower than the predetermined level V2 that requires recharging (at time t8), the charging of the buffer 72 is stopped, and the electric energy accumulated in the buffer 72 is charged into the buffer 76. The converter 74 is controlled as follows.
[0076]
As a result, when the tendency of the charge level of the buffer 76 to decrease becomes moderate, the charge level of the buffer 72 decreases. However, when the load 82 ends (at time t9), the charge level of the buffer 76 increases. Begin to.
[0077]
Then, when a relatively large load 84 is generated (at time t10), the charge level of the buffer 76 starts to rapidly decrease. When the charge level of the buffer 76 becomes equal to or lower than a predetermined level V4 that requires quick charge (at time t11), the converter 74 is controlled so that the electric energy supplied from the buffer 72 to the buffer 76 is maximized. To do. Thereby, the charge level of the buffer 72 falls rapidly.
[0078]
When the load 84 ends, the charge level of the buffer 76 rises, and when the charge level of the buffer 72 is less than the predetermined level th1 when the charge level of the buffer 72 is lower than the predetermined level th1 when the charge level becomes equal to or higher than the predetermined level V3 that does not require quick charging. Charging from the buffer 72 to the buffer 76 is stopped, and charging to the buffer 72 is started.
[0079]
Similarly, when the charge level of the buffer 72 becomes equal to or higher than the predetermined level th1 (at time t13), the charge of the buffer 72 is stopped and the charge to the buffer 76 is started. When the charge level of the buffer 76 becomes equal to or higher than the predetermined level V1 (time t14), the charging of the buffer 76 is stopped and the charging of the buffer 72 is started.
[0080]
Thus, in this embodiment, by providing two stages of buffers, power generation by the fuel cell 30 is continuously performed, and when the charge level of the buffer 72 is less than the predetermined level th1, the buffer 72 is preferentially charged. When the charge level of the buffer 76 is equal to or lower than the predetermined level V2, the buffer 76 is preferentially charged. When the buffer 76 becomes equal to or lower than the predetermined level V2 that requires recharging, the buffer 72 is charged to the buffer 76. Thereby, the digital camera 10 can be stably operated for a long time.
[0081]
Further, when the charge level of the buffer 76 becomes equal to or lower than the operation limit level V5, a function that cannot be operated unless the charge level of the buffer 76 exceeds the operation limit level V5 (such as flash photography) is prohibited. . Then, the prohibition is canceled when the charge level of the buffer 76 exceeds, for example, the operation restriction level V5. Accordingly, the operation can be continued in a reduced function without stopping the entire apparatus, the operation can be stabilized and the convenience can be improved.
[0082]
In the present embodiment, the case where two buffers are provided has been described. However, as shown in FIG. In this case, the converter 74 has a function of blocking between the buffer 76 and the fuel cell. In this case, as shown in FIG. 9, when the load level is equal to or higher than a predetermined level Load, the buffer 74 is disconnected from the fuel cell 30 by the converter 74 and the fuel cell 30 generates power. Stop. As a result, when a large load such as flash photography occurs, it is possible to prevent the current from flowing backward from the buffer 76 to the fuel cell 30 side, thereby protecting the fuel cell 30.
[0083]
In this embodiment, the digital camera has been described as an example. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to a mobile terminal such as a mobile phone or a PDA.
[0084]
【The invention's effect】
As described above, according to the present invention, there is an effect that it can be stably driven for a long time.
[Brief description of the drawings]
1A is a front view of a digital camera, and FIG. 1B is a rear view of the digital camera.
FIG. 2 is a perspective view showing a fuel cell and a heater.
FIG. 3 is a circuit block diagram of the digital camera.
FIG. 4 is a configuration diagram of a fuel cell.
FIG. 5 is a block diagram of a charging mechanism of a digital camera.
FIG. 6 is a diagram for explaining a power transition of a fuel cell, a power transition of a first-stage buffer, and a power transition of a second-stage buffer.
FIG. 7 is a diagram for explaining charge control of a first-stage buffer and a second-stage buffer.
FIG. 8 is a block diagram illustrating another example of a charging mechanism of a digital camera.
FIG. 9 is a diagram for explaining the power transition of the fuel cell and the power transition of the buffer.
[Explanation of symbols]
10 Digital camera
14 Shooting lens
16 Finder
18 Flash device
30 Fuel cell
32 Heater
58 Image processor
64 μ computer for control
65 Backlight
66 switches
70, 72 converter
72, 76 buffers
78 switch
80 thermometer

Claims (5)

A fuel cell that generates electric energy by chemically reacting the supplied fuel; and
Charging means for charging the electric energy generated by the fuel cell and supplying the charged electric energy to each part of the apparatus;
Control means for controlling power generation by the fuel cell and charging by the charging means according to the load level of the device;
Mobile device equipped with. The control unit further includes a blocking unit that blocks between the charging unit and the fuel cell, and the control unit stops power generation of the fuel cell when the load level of the device exceeds a predetermined level. The portable device according to claim 1, wherein the blocking unit is controlled so that the charging unit and the fuel cell are blocked. The charging means charges a first buffer for charging the electric energy generated by the fuel cell, and charges the electric energy charged in the first buffer, and supplies the charged electric energy to each part of the apparatus. 2. The portable device according to claim 1, further comprising: a blocking unit configured to block between the first buffer and the second buffer. When the level of the electric energy charged in the second buffer becomes equal to or lower than a predetermined level, the control means sets the electric energy charged in the first buffer at a predetermined predetermined supply level. The first buffer is controlled so that the second buffer is charged, and when the level of electrical energy charged in the second buffer becomes a quick charge level lower than the predetermined level. 4. The portable device according to claim 3, wherein control is performed so that the electric energy charged in the second buffer is charged in the second buffer at a high supply level higher than the predetermined supply level. The control means restricts a predetermined operation of the device when the electric energy charged in the second buffer falls below an operation restriction level lower than the quick charge level. The portable device according to claim 4.

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