JP2001352510A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a conventional digital camera having a plural ity of memories in which the selection of the memories is left to a user but he does not have criteria as to the choice of the memories because he is not grasping the difference in data write speed of each memory in spite of the fact that it is an important factor in the case of especially writing moving picture data to each memory resulting in selecting the memories in a non-com mittal way. SOLUTION: The digital camera of this invention to which read/write enable external recording media are loaded is provided with a write speed detection section that detects a data write speed of each external recording medium by actually writing investigation data to each external recording medium and with a write medium selection section that selects an external recording medium to which recording data are written on the basis of the detected write speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a digital camera. In particular, the present invention relates to a digital camera having a plurality of memories such as smart media.

[0002]

2. Description of the Related Art As digital cameras have become more sophisticated, digital cameras equipped with a plurality of external recording media have been proposed. A typical example of the external recording medium is a memory such as a smart media. By making it possible to mount a plurality of memories, it is possible to handle a larger amount of data and to record data in different types of memories.

Japanese Patent Application Laid-Open No. H11-146328 discloses a digital camera that can use a plurality of recording media.
Japanese Patent Application Laid-Open No. 8-317326 discloses a digital camera that switches an appropriate recording medium according to the state of the power supply voltage of the camera and records an image.

[0004]

In a digital camera having a plurality of memories, the data writing speed differs for each memory. The data writing speed is an important factor in writing data normally. However, usually, a user who uses a digital camera does not know the speed of writing data between memories. Therefore, the memory to which the data is to be written has been determined by the user appropriately selecting it.

For example, data recorded by a digital camera includes moving image data and still image data. Moving image data, unlike still image data, has a very large data amount per unit time. If the writing speed of the memory is not sufficient with respect to the amount of moving image data per unit time, dropping of frames or sound interruption of moving image data may occur. Moving image data in which frames are dropped or sound is cut reduces the interest in viewing, so a means for preventing dropped frames and the like is required.

However, regarding a conventional digital camera equipped with a plurality of memories, as described above, no consideration is given to the relationship between the writing speed of the used memory and the amount of data to be written.

The writing speed of a memory differs between different types of memories. Furthermore, even if the type of memory is the same, the type may be different depending on the manufacturer of the memory used or the individual difference of the memory. For this reason, although one memory has a sufficiently high writing speed, moving image data may be written to the other memory having a low writing speed, which may cause dropping of frames or the like.

Accordingly, an object of the present invention is to provide a digital camera capable of solving 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.

[0009]

That is, the present invention relates to a digital camera to which a plurality of readable and writable external recording media can be mounted. This digital camera, based on the detected writing speed, based on the writing speed detecting unit that detects the data writing speed of each external recording medium by actually writing the investigation data to each of the plurality of external recording media,
A writing medium selection unit for selecting an external recording medium to which the recording data is to be written.

The writing speed detecting section may detect the data writing speed by actually writing the investigation data to the mounted external recording medium when the external recording medium is mounted on the digital camera. When detecting the data writing speed of the attached external recording medium, the writing speed detection unit may actually write the survey data to the already installed external recording device to detect the data writing speed. .

The writing speed detector may detect the data writing speed by actually writing the survey data each time the recording data is written to the external recording device.

The survey data may be prepared separately from the recording data. The investigation data may be a part of the recording data.

The investigation data, which is a part of the recording data, is written in parallel to a plurality of external recording media, and is written to the external recording medium determined to have a faster data writing speed, following the investigation data. Recording data may be written.

The writing medium selecting section may select either an external recording medium having a higher data writing speed or an external recording medium having a lower data writing speed according to the recording data.

[0015] The recording medium selecting section may select an external recording medium having a higher data writing speed when the recording data is moving image data.

In the digital camera of the present invention, when a certain external recording medium is mounted on the digital camera for the first time, the survey data may be actually written and the obtained data writing speed may be recorded.

In the digital camera according to the present invention, when an external recording medium on which a data writing speed is recorded is mounted, the writing medium selecting unit refers to the recorded data writing speed to write an external recording medium. A recording medium may be selected.

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. 1 shows the appearance of a digital camera 10 according to an embodiment of the present invention. The appearance differs from a normal digital camera in that two slots for external recording media are provided. In the present embodiment, two smart media slots into which smart media can be mounted as external recording media are provided. In addition, examples of the external recording medium include a memory stick and a compact flash (registered trademark).

Two or more slots for external recording media may be provided, or slots for different types of external recording media may be provided. For example, two slots for smart media and a slot for compact flash may be provided.

FIG. 2 shows the configuration of the digital camera 10 according to the embodiment. A configuration characteristic of the embodiment will be described in detail with reference to FIG. Note that the digital camera according to the present embodiment includes a slot for an external recording medium as an example of a medium mounting unit for an external recording medium.

The digital camera 10 shown in FIG. 1 mainly includes an imaging unit 20, an imaging control unit 40, and a processing unit 6.
0, a display unit 100, and an operation unit 110.

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 first, white balance is adjusted.
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 imaging control unit 40 includes a zoom drive unit 4
2. It has a focus drive unit 44, an aperture drive unit 46, a shutter drive unit 48, an imaging system CPU 50 that controls them, a distance measurement sensor 52, and a photometry sensor 54. The driving units such as the zoom driving unit 42 each have a driving unit such as a stepping motor. When a release switch 114 described later 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 imaging system CPU 50 determines 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 emission of the strobe light 36 based on the photometric data, and at the same time adjusts the aperture of the aperture 24. 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
The main C that controls the whole, especially the processing unit 60 itself
PU 62 and memory control unit 6 controlled by PU 62
4, a YC processing unit 70, an external recording medium control unit 74, a compression / decompression processing unit 78, and a communication I / F unit 80. Main CP
U62 is connected to the imaging CPU 50 by serial communication or the like.
Exchange necessary information with Main CPU 62
Is supplied from the clock generator 88. The clock generator 88 also provides clocks having different frequencies to the imaging system CPU 50 and the display unit 100, respectively.

The main CPU 62 is provided with a character generator 84 and a timer 86. The timer 86 is backed up by a battery 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 memory control unit 64 includes a nonvolatile memory 66
And the main memory 68. Non-volatile memory 66
The digital camera 1 includes an EEPROM (electrically erasable and programmable ROM), a flash memory, and the like, and stores setting information by a user and adjustment values at the time of shipment.
The data to be held even while the power supply of 0 is off is stored. The non-volatile memory 66 may have a main CPU
62, a boot program and a system program may be stored. On the other hand, the main memory 68 generally has a DR
It is composed of a relatively inexpensive and large-capacity memory like an AM. The main memory 68 functions as a frame memory for storing data output from the imaging unit 20,
It has a function as a system memory for loading various programs and a function as a work area. The nonvolatile memory 66 and the main memory 68 exchange data with each unit inside and outside the processing unit 60 via the main bus 82.

The YC processing section 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 transmitted to the external recording medium slot A under the control of the external recording medium control unit 74.
Alternatively, the data is written on the external recording medium mounted in the external recording medium slot B. Whether the external recording medium control unit 74 writes to the external recording medium slot A or the external recording medium slot B is selected by a writing medium management device 75 described later with reference to FIG.

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 on an external recording medium, the data is first supplied to a compression / decompression processing section 78 under the control of an external recording medium control section 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 external recording medium control unit 74 generates and logically converts signals required between the main bus 82 and the external recording medium (slot) in accordance with the signal specifications recognized for the external recording medium and the bus specifications of the main bus 82. Or voltage conversion. The digital camera 10 may include optional devices other than the external recording medium.
It may be configured to support A-compliant standard I / O cards. In that case, the bus control L for PCMCIA
SI or the like may be provided.

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 (registered trademark). 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, for example, data may be exchanged with an external device such as a printer by using 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 electric members necessary for the user to set or instruct the operation of the digital camera 10 and its mode. 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 half-pressing, captured images are captured by full-pressing, and are recorded in the main memory 68, an external recording medium or the like 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”,
There are “printing”, “decision / save”, “display switching”, and the like. The operation unit 110 is also used for selecting an external recording medium. The zoom switch 118 determines a zoom magnification.

The main operation of the above configuration is as follows. First, the power switch 11 of the digital camera 10
2 is turned on, and power is supplied to each part of the camera. The main CPU 62 determines whether the digital camera 10 is in the shooting mode or the playback mode by reading the state of the function setting unit 116.

When the camera is in the shooting mode, the main C
The PU 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. Once the adjustment is complete,
Characters such as "standby" are displayed on the LCD monitor 102 to inform the user of the fact, and then the release switch 114 is fully pressed. Release switch 11
When the button 4 is fully pressed, the shutter 26 is closed after a predetermined shutter time, and the accumulated charges of the CCD 30 are 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, then processed by the YC processing unit 70 and the compression / decompression processing unit 78, and is recorded on the external recording medium via the external recording medium control unit 74. The recorded image is
The frozen image is displayed on the LCD monitor 102 for a while, and the user can know the photographed image. Thus, a series of photographing operations is completed.

On the other hand, when the digital camera 10 is in the reproduction mode, the main CPU 62 reads out the last photographed image from the main memory 68 via the memory control unit 64,
This is displayed on the LCD monitor 102 of the display unit 100.

In this state, when the user instructs "forward" or "reverse" in the function setting section 116, images taken before and after the currently displayed image are read out and displayed on the LCD monitor 102. You.

The above is the outline of the overall configuration of the digital camera 10 and the operation thereof. Next, a characteristic configuration of the present embodiment will be described.

FIG. 3 shows an outline of the writing medium management device 75. The configuration of the writing medium management device 75 is realized mainly by the processing unit 60. The main CPU 62 and the programs stored or loaded in the main memory 68 or the non-volatile memory 60 suitably function. The writing medium management device 75 detects a data writing speed for each external recording medium, and selects an external recording medium to be used for data writing based on the detected data writing speed.

The writing speed detecting section 210 detects the data writing speed for each external recording medium by actually writing the investigation data for detecting the writing speed on the external recording medium (benchmark test). The data actually written to the external recording medium when the data writing speed is detected is referred to as investigation data. On the other hand, data such as still image data, moving image data, and audio data recorded on an external recording medium is referred to as recording data.

For detecting the data writing speed, for example, data having a capacity of 2 MB is prepared as investigation data.
If it takes 2 seconds to write 2MB data,
The data writing speed is 2 MB / 2 seconds = 1 MB / second.
The investigation data may be a plurality of investigation data having different capacities, and the capacity of the investigation data may be selected according to the recording data to be written.

When there is recording data, a part of the recording data can be used as the investigation data. In this case, a part of the recording data serving as the investigation data is actually written on the external recording medium. By using a part of the recording data as the investigation data, the digital camera not only does not need to have the investigation data separately, but also can detect the data writing speed according to the recording data actually written. Therefore, selection of the external recording medium is performed more finely. This process is suitable when the order of the data writing speed between the external recording media is reversed due to the data capacity of the recording data.

A part of the recording data serving as the investigation data may be simultaneously written to a plurality of external recording media.
From the result of this writing, the data writing speed for each external recording medium is detected. Based on the detected data writing speed,
An external recording medium with a higher data writing speed is selected.
After the writing of a part of the recording data is completed, the remaining recording data is continuously written to the selected external recording medium. On the other hand, data writing to the unselected external recording medium is interrupted, and part of the written recording data is erased. As a result, the time required for selecting the external recording medium from the writing of the investigation data can be omitted, so that the writing of the recording data can be performed more smoothly.

The data writing speed may be calculated from the data volume written within a predetermined time. For example, when the predetermined time is 2 seconds, the data writing speed is calculated from the amount of data written in 2 seconds.

The data writing speed detected in this way is recorded in the writing speed database 230. FIG.
Is an example of the writing speed database 230. The writing speed database 230 records the detected data writing speed and the date and time when the writing speed was detected for the recording medium ID determined for each external recording medium. The data writing speed recorded in the database can be referred to when the data writing speed needs to be compared after the external recording medium is mounted. Further, it is also possible to refer to when the external recording medium on which the data writing speed has been recorded is once removed and mounted again.

The detected data writing speed may be recorded on each external recording medium in a readable state so that it can be used later.

The writing medium selection unit 220 included in the writing medium management device 75 outputs the data writing speed detected by the writing speed detection unit 210, the data writing speed recorded in the writing speed database 230, or The external recording medium on which the recording data is to be written is selected based on the data writing speed recorded on the external recording medium.

Since it is important to consider the timing of speed detection in detecting the data writing speed, the writing medium management device 75 also has components related to the detection timing. The recording medium attachment detection unit 250 detects attachment of the external recording medium to the digital camera. The detection of the attachment of the external recording medium is used for setting the data writing speed detection timing described below.

The speed detection timing setting section 240 sets the timing for detecting the data writing speed of the external recording medium. 5 and 6 show examples of settable detection timings. The following example is a typical example assuming a digital camera to which two external recording media can be mounted. The two external recording media are called a first recording medium and a second recording medium, respectively.

At the detection timing (A) shown in FIG. 5, when an external recording medium is mounted on the digital camera, the data writing speed of the external recording medium is detected. That is, when the first recording medium is mounted, only the data writing speed detection of the first recording medium is performed. On the other hand, when the second recording medium is mounted, only the data writing speed of the second recording medium is detected. In this case, since it is only necessary to detect the data writing speed of each external recording medium once, it is simple.

FIG. 7 shows a flowchart from the mounting of the first recording medium to the selection of the writing medium when the detection timing (A) is set. First, the mounting of the first recording medium is detected by the recording medium mounting detecting unit 250 (S1).
0). When the mounting of the first recording medium is detected, the writing speed detecting unit 210 detects the data writing speed by actually writing the inspection data on the first recording medium (S2).
0). The detected data writing speed is recorded in the writing speed database 230 so that it can be referred to later (S30).
The data writing speed of the second recording medium is read from the writing speed database 230 (S40). The data writing speeds of the first recording medium and the second recording medium are compared, and one of the external recording media is selected (S50).

At another detection timing (B) shown in FIG. 5, when the external recording medium is mounted on the digital camera and there is another external recording medium already mounted, The data writing speed of the already mounted external recording medium is detected together with the external recording medium. That is, even if the data writing speed of the second recording medium has already been detected, the data writing speed of the second recording medium is detected again when the first recording medium is mounted. Accordingly, when the data writing speed of the second recording medium is once detected, and the data writing speed changes due to data writing or the like, the changed data writing speed can be detected. Useful for selecting an external recording medium.

Next, at the detection timing (C) shown in FIG. 6, when a plurality of external recording media are already mounted on the digital camera, all the recording data that needs to be written is generated. The data writing speed of the external recording medium is detected at a time. In this case, even if the first recording medium and the second recording medium are mounted, the data writing speed is not detected. When recording data is generated by capturing a moving image or the like, the data writing speed of the first recording medium and the second recording medium is detected.

The writing medium management device 75 can also select an external recording medium to which data is to be written according to the type of recording data. The recording data type acquisition unit 260 acquires the type of recording data. Based on the acquired data type, the writing medium selection unit 220 selects an external recording medium to which data is to be written.

FIG. 8 shows an example in which an external recording medium to which data is written is determined by the type of recording data. In FIG. 7, it is assumed that the first recording medium has a higher data writing speed than the second recording medium. The data type of the recording data is acquired by the recording data type acquisition unit 260, and an external recording medium for writing is selected based on the acquired data type.
In this case, the moving image data is stored in the first data having a higher data writing speed.
The still image data is written to the recording medium, and the still image data is written to the second recording medium.

According to this, the still image data which does not require a high writing speed is written to the second recording medium having a lower writing speed, so that the load on the first recording medium can be reduced. In addition, it is possible to save the free space of the first recording medium that requires a larger capacity when writing moving image data.

Next, a digital camera according to another embodiment of the present invention will be described. FIG. 9 schematically illustrates a writing medium management device 75 included in the digital camera 10 according to another embodiment. The basic configuration of the writing medium management device 75 is the same as that of the writing medium management device 75 of the embodiment shown in FIG. A feature of the present embodiment is that a writing medium is selected based on the type of the attached external recording medium. The medium type acquisition unit 270 acquires the type of the attached external recording medium. The data writing speed is obtained based on the type of the obtained external recording medium. The data writing speed for each type of external recording medium is stored in the writing speed database 230 and can be referred to at any time.

As described above, according to the present invention, an external recording medium to which data is to be written from a plurality of external recording media is appropriately selected in consideration of the actually detected data writing speed of the external recording medium. Furthermore, considering the type of data to be written,
An external recording medium to which data is to be written is appropriately selected.

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. It should be noted that such modified or improved embodiments may be included in the technical scope of the present invention.
It is clear from the description of the claims.

[0066]

As is apparent from the above description, according to the present invention, there is provided a digital camera which automatically selects an external recording medium to which data is to be written in consideration of the data writing speed of the external recording medium. Can be.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an appearance of a digital camera according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a digital camera according to an embodiment.

FIG. 3 is a block diagram schematically showing a write medium management device.

FIG. 4 is a diagram showing an example of a writing speed database.

FIG. 5 is a diagram showing an example of detection timings (A) and (B) for detecting a data writing speed.

FIG. 6 is a diagram illustrating an example of a detection timing (C) for detecting a data writing speed.

FIG. 7 shows a case where a detection timing (A) is set.
FIG. 7 is a diagram showing a flowchart from when a first recording medium is mounted to when a writing medium is selected.

FIG. 8 is a diagram showing an example in which an external recording medium to which data is written is determined according to the type of recording data.

FIG. 9 is a schematic block diagram of a writing medium management device included in a digital camera according to another embodiment.

[Explanation of symbols]

 Reference Signs List 10 digital camera 74 external recording medium control unit 200 external recording medium management device 210 writing speed detection unit 220 writing medium selection unit 230 writing speed database 240 speed detection timing setting unit 250 recording medium attachment detection unit 260 recording data type Acquisition unit 270 Medium type acquisition unit

Continued on front page F-term (reference) 2H054 AA01 5C022 AA00 AA13 AB22 AB66 AC42 AC52 AC56 AC69 AC74 AC80 5C052 AA17 GA01 GB01 GC05 GD09 GE06 GE08

Claims (10)

[Claims] 1. A digital camera to which a plurality of readable and writable external recording media can be mounted, wherein a data write speed of each of the plurality of external recording media is written by actually writing survey data to each of the plurality of external recording media. A digital camera comprising: a writing speed detecting unit for detecting the recording speed; and a writing medium selecting unit for selecting an external recording medium to which the recording data is to be written, based on the detected writing speed. 2. The writing speed detecting section detects a data writing speed by actually writing investigation data into the attached external recording medium when the external recording medium is attached to the digital camera. The digital camera according to claim 1, wherein: 3. The writing speed detecting unit, when detecting a data writing speed of an attached external recording medium, further writes survey data to an already attached external recording device, and further writes a data writing speed. The digital camera according to claim 2, wherein the digital camera detects 4. The apparatus according to claim 2, wherein the writing speed detecting unit detects the data writing speed by actually writing the inspection data every time the recording data is written to the external recording device. Digital camera as described. 5. The digital camera according to claim 1, wherein the survey data is prepared separately from the recording data. 6. The digital camera according to claim 1, wherein the investigation data is a part of the recording data. 7. The investigation data, which is a part of the recording data, is written in parallel to the plurality of external recording media, and is written to an external recording medium determined to have a faster data writing speed. The digital camera according to claim 6, wherein the recording data is written following the survey data. 8. The writing medium selection unit selects one of an external recording medium having a higher data writing speed and an external recording medium having a lower data writing speed according to the recording data. The digital camera according to claim 1, wherein: 9. The digital camera according to claim 8, wherein the writing medium selection unit selects an external recording medium having a higher data writing speed when the recording data is moving image data. . 10. When a certain external recording medium is attached to a digital camera for the first time, survey data is actually written,
A write speed recording unit for recording the obtained data write speed, and when an external recording medium on which the data write speed is recorded is attached, the write medium selecting unit refers to the recorded data write speed. 2. The digital camera according to claim 1, wherein an external recording medium to which the recording data is written is selected.