JP2009140539A - Portable electronic devices - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the accuracy in detecting a free fall is deteriorated due to the detection of centrifugal force in the free fall accompanied by rotation, because conventional free fall detection determines the free fall when all of three axes of a three-axis acceleration sensor are at a prescribed value or lower. <P>SOLUTION: In an imaging apparatus including a free fall detection means which determines a free fall when detected accelerations in three directions by the three-axis acceleration sensor are simultaneously at a prescribed threshold or lower, a free fall determination criterion by the three-axis acceleration sensor varies based on the state of cables. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is effective for a portable electronic device such as a digital video camera, particularly a video camera using a hard disk drive (HDD) which is a fixed recording medium having a large recording capacity as a video recording medium.

  In recent digital video cameras, in addition to those using conventional magnetic tape as a video recording medium, random access is possible, and the recorded video can be easily called and searched, and recorded before recording. There are products that use an optical disc such as a DVD as a recording medium, which has greatly improved usability, such as no fear of overwriting the contents. As mentioned above, this video camera is not a medium that has realized a capacity of 4.7 GB with a diameter of 12 cm, but has a capacity of 1.4 GB with a diameter of 8 cm while maintaining the same standard as this 12 cm disk. By adopting the media we have, we have realized a highly portable video camera that is the same as a conventional DV video camera.

  However, since the DVD medium having a diameter of 8 cm has a small capacity of 1.4 gigabytes as described above, it is a general recording rate for recording NTSC standard image quality (SD: vertical 480 × horizontal 720 pixels). Under the recording condition of 6 megabits / second, only about 30 minutes can be recorded. In addition, there is a mode of 3 megabits / second as the long-time mode, and recording can be performed for 1 hour under these conditions, but the image quality is considerably deteriorated. Further, only 20 minutes can be recorded under the condition of 9 megabits / second in the high image quality mode. Furthermore, recently, video cameras compatible with so-called high-definition image quality (HD: vertical 1080 × horizontal 1440 pixels) are becoming widespread, but at a recording rate of 12 megabits / second in this high-definition image quality mode, the recording time is 15 minutes and 2.6. Even with a dual-layer disc with a capacity of gigabytes, only 27 minutes can be recorded. Therefore, if you want to shoot in a group such as a trip, an athletic meet, or a school performance, you have to prepare and carry a lot of media.

  In order to solve this problem, a video camera using a hard disk drive (HDD), which is a large-capacity recording medium, as a video recording medium has recently been released. This video camera has a built-in HDD with a 1.8-inch diameter disk and a large capacity of 30 GB, and records for 10 hours and 50 minutes under a recording condition of 6 megabits / second, which is a general recording rate of standard image quality. The high-definition image quality mode of 15 megabits / second realizes recording for 4 hours, and the user can shoot without worrying about the remaining amount.

  However, the HDD has a structure in which the magnetic head floats with respect to the disk surface due to a rotating air current, and the magnetic head is in contact with the disk surface due to shock or vibration, and the disk surface is damaged. In this case, it may become impossible to read / write the data in that part. In order to solve this problem, a video camera that employs an HDD as an image recording medium has a built-in system for detecting a free fall state using a three-dimensional acceleration sensor, and the camera body is in a free fall state during shooting. When a thing is detected, the power supply of the main body is shut off or a predetermined command is transmitted to the HDD, and the magnetic head of the HDD is installed outside the disk, which is called a lamp shown in FIG. By quickly moving onto the member that supports the arm on which the head is mounted, it is configured to withstand the impact of dropping.

  Here, a method of detecting free fall by the three-dimensional acceleration sensor will be described. As shown in FIG. 6A, the three-dimensional acceleration sensor detects the acceleration applied to the sensor in each of the three axis directions including the X axis, the Y axis, and the Z axis orthogonal to each other, and incorporates the sensor. For example, when the device is stationary with the Z axis in the vertical direction, the Z axis detects 1G, which is gravitational acceleration, and the other X and Y axes detect 0G. ing. If the posture of the device is changed and the Y-axis is set to the posture that matches the vertical direction and the Z-axis is set to the posture that matches the vertical direction, the Y-axis and the Z-axis detect 1G, respectively. The axis detects 0G. When this device is in a free fall state, as shown in FIG. 6 (c), 0G is detected also in the vertical axis, and almost 0G is detected in all three axes, that is, almost 0G is detected in all three axes. When it is detected, it can be determined that the main body is freely falling. Actually, in order to perform detection irrespective of the axial direction, a vector synthesized value obtained by vector synthesis of detected acceleration values in the three axial directions is used, and the scalar amount of this vector synthesized value is 0.4 G, etc., taking into account detection errors and the like. Generally, it is determined that a free fall occurs when the value falls below a predetermined value.

As another conventional example, the following Patent Document 1 and Patent Document 2 can be cited.
JP 2005-078767 JP 2005-346840

  However, the position of the three-axis acceleration sensor mounted on the device does not necessarily match the position of the center of gravity of the device body. On the other hand, when some force is applied to the device and rotation occurs during free fall, the rotation is performed around the center of gravity of the device. That is, when the mounting position of the three-axis acceleration sensor and the position of the center of gravity of the device are separated from each other, the vector composite value of the three-dimensional acceleration sensor is influenced by centrifugal force and is in free fall. In some cases, the amount of scalar did not fall below a predetermined value, and a free fall state could not be detected. In particular, when a video input / output cable and a power cable are connected to the main body, there is a case where the cable is pulled by these cables during the fall and a strong rotation is applied. In addition, when the cable is connected, there is a situation of dropping different from that when the cable is connected alone, such as when the cable is hooked on the connected cable and dropped from the desk.

  The present invention has been made in view of the above points, and a first object thereof is to provide a portable electronic device that can detect free fall even when the device falls while rotating.

  It is a second object of the present invention to provide a portable electronic device that can detect a free fall even when a significant rotation is applied by being pulled by a cable connected to the main body during the fall.

  It is a third object of the present invention to provide a portable electronic device that can reliably protect a recording medium even when a connected cable is pulled and is expected to lead to a fall of the main body.

  The portable electronic device according to the first invention of the present application for realizing the object is free from a body from acceleration detection means for detecting acceleration in three axial directions orthogonal to each other and output values of the acceleration detection means. Operates the main body by a free fall judging means for judging whether or not it is in a fall state, a recording medium impact protecting means for protecting a recording medium for recording and reading data from impact according to a judgment result of the free fall judging means Connect the power supply terminal to connect the power cable to supply the power to be connected, the analog signal terminal to connect the analog signal cable to input or output the analog signal, or the digital signal cable to input or output the digital signal In a portable electronic device having a digital signal terminal, the power supply terminal or the analog signal terminal Has connection cable detection means for detecting whether the cable is connected to each of the digital signal terminals, and according to the detection result of the detected cable detection means, the free fall determination means is in a free fall state. It is characterized in that the threshold value of the output of the acceleration detecting means, which is determined to be present, changes.

  Furthermore, a portable electronic device according to a second aspect of the present invention is the portable electronic device according to the first aspect, wherein the free fall determination means has output values in three directions by the acceleration detection means. At the same time, it is determined that the main body is in a free-fall state when the threshold value is below the threshold value, and when the cable detection means detects that the cable is connected to a predetermined terminal, Output threshold for determining free fall in the axial output of the acceleration detection means, which is close to the axial direction connecting the position of the terminal to which the cable is connected and the position where the acceleration detection means is mounted. It is characterized by an increase in value.

  A portable electronic device according to a third aspect of the present invention is the portable electronic device according to the first aspect, wherein the free fall determining means vectorizes the three-direction output of the acceleration detecting means. The main body is determined to be in a free fall state when the absolute value of the vector composite value obtained by combining is equal to or less than a predetermined value, and the cable is connected to a predetermined terminal by the cable detection means. Is detected with respect to the axial output of the acceleration detection means, which is close to the axis connecting the position of the terminal to which the cable is connected and the position where the acceleration detection means is mounted. When the absolute value of the vector composite value obtained by vector synthesis of the value obtained by multiplying the coefficient less than 1 and the output in the other two directions is equal to or less than a predetermined value, it is determined to be in a free fall state Characteristic One in which you composed.

  Further, according to a fourth aspect of the present invention, there is provided a portable electronic device comprising: an acceleration detection means for detecting accelerations in three axial directions orthogonal to each other; A free fall judging means for judging whether or not, a recording medium impact protecting means for protecting a recording medium for recording and reading data from an impact according to a judgment result of the free fall judging means, and a power source for operating the main body A power supply terminal for connecting a power cable for connecting, an analog signal terminal for connecting an analog signal cable for inputting or outputting an analog signal, or a digital signal terminal for connecting a digital signal cable for inputting or outputting a digital signal A portable electronic device having the power supply terminal, the analog signal terminal, or the digital Each having a connection cable detection means for detecting whether the cable is connected to each of the terminal terminals, and when the connection cable detection means detects that the cable is connected, When any change in acceleration is observed with respect to one of the two axes other than the vertical axis, the free fall determining means determines that the free fall state is present.

  Further, a portable electronic device according to a fifth aspect of the present invention is the portable electronic device according to the first to fourth aspects, wherein the signals handled by the digital signal cable are the analog video signal and the analog signal. It is encoded video / audio data that is superimposed after the audio signal is digitized and compressed and encoded.

  A portable electronic device according to a sixth aspect of the present invention is the portable electronic device according to the first to fifth aspects, wherein the signal handled by the digital signal cable is the analog video signal and the analog signal. The audio signal is digitized and is uncompressed stream data of the encoded video and audio superimposed.

  Furthermore, a portable electronic device according to a seventh aspect of the present invention is the portable electronic device according to any one of the first to sixth inventions, wherein a signal handled by the digital signal cable is transmitted to the portable electronic device. It is a control signal for controlling from the outside.

  A portable electronic device according to an eighth aspect of the present invention is the portable electronic device according to the first to seventh inventions, wherein the recording medium is a hard disk drive, and the drive includes A ramp that is an arm holding mechanism for protecting the magnetic head and an arm that supports the magnetic head when the magnetic head is outside the disk, and the free fall detecting means detects a free fall state of the main body Is characterized in that the recording medium protection means operates, and the magnetic head is forcibly moved to the ramp and is held by the ramp.

  Furthermore, a portable electronic device according to a ninth aspect of the present invention is the portable electronic device according to the first to eighth aspects, wherein the data buffer temporarily stores data to be recorded on the recording medium. The recording data is continuously accumulated in the data buffer while the recording medium protection means is operating and data recording on the recording medium is stopped.

  According to the present invention, even when rotation is applied by the cable connected to the main body during the fall, the output of acceleration in the direction in which the centrifugal force is most affected is evaluated to be small according to the terminal position of the connected cable. Since the free fall determination is performed, it is possible to provide a portable electronic device that can reliably determine the free fall without being affected by the centrifugal force.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  An embodiment in which the present invention is applied to a video camera will be described with reference to the drawings.

  FIG. 1 is a block diagram of the video camera of this embodiment. In the figure, 101 is a photographic lens that captures a subject, 102 is an aperture that controls the amount of light to an image sensor described later, 103 is an image sensor that converts the captured subject into an image signal, and 104 samples and holds the image signal. The CDS / AGC 105 for setting an appropriate signal level is a digital signal processing circuit that performs A / D conversion on the image signal from the CDS / AGC and performs digital signal processing, and 106 is raw data from the digital signal processing circuit. A frame memory 107 for storing each frame, and a pixel number adjustment circuit 108 for adjusting an appropriate number of pixels so that the pixels of the frame memory can be recorded in the later-described MPEG2 or MPEG4 system. An image / sound data bus 109 for moving back and forth between the image data and sound data described later, Both are microphones for collecting sound recorded on a removable disk, which will be described later, 110 is an amplifier for amplifying the sound signal from the microphone to an appropriate level, and 111 is an A / D converter for A / D converting the amplified sound signal. A D converter 112 is a liquid crystal panel that displays reproduced image data from an MPEG2 codec 114 (to be described later) in the reproduction mode, a liquid crystal panel that displays an image captured by the image sensor 103 at the time of photographing, and a liquid crystal driver 114 that drives the liquid crystal panel. MPEG2 codec 115 compresses and encodes a digital image signal from the image bus as a moving picture by the MPEG2 system, and decompresses MPEG2 compressed data recorded in a flash memory, which will be described later. 115 is a compression encoding from the MPEG2 codec. The data is stored in the hard disk A stream buffer for temporarily recording and holding before recording in the disk drive 119, a video output terminal 116 for outputting an analog video signal from an NTSC encoder, which will be described later, and an object displayed on the liquid panel 118 An NTSC encoder that converts the same image into an analog signal and outputs it to the video output terminal 116, a disk driver 118 that reads / writes data from / to an optical disk 119 described later, and an MPEG2 image from the image / audio data bus 109 An optical disk 120 for recording data, a USB terminal for outputting data from a USB interface 121 (to be described later), a USB controller 121 for outputting MPEG2 format image data recorded on the optical disk 119 directly to the outside, and 122, The user can An operation key 123 for performing an operation controls a mode of the entire device, a main microcomputer that detects the operation key 122 and controls execution of various functions, and a main microcomputer 124 stores temporary data. RAM, 125 is an EEPROM which is a non-volatile memory for storing a predetermined state of the main microcomputer, 126 is a control signal bus through which a control signal from the main microcomputer 124 and a signal from the operation key 122 come and go, Reference numeral 127 denotes a three-dimensional acceleration sensor composed of acceleration sensors in three axial directions orthogonal to each other, and 128 denotes a cable connection detection switch that detects the presence / absence and type of a cable connected to the main body.

  With the above configuration, the operation of the video camera of the present invention will be described with reference to the drawings. FIG. 2 is a diagram showing the configuration of the present embodiment, in which FIG. 2A is the three-dimensional acceleration sensor, and the acceleration in the X-axis, Y-axis, and Z-axis directions with respect to the element An acceleration sensor that detects FIG. 2B shows the mounting position of the three-dimensional acceleration sensor in the video camera of the present embodiment. As shown in FIG. 2, the Y-axis of FIG. FIG. 2C is a diagram showing an output waveform of the three-dimensional acceleration sensor. Among these, the part (d) is a normal waveform, and the output of the X axis and the Z axis in FIG. 2 (a) is 0G, but the Y axis outputs 1G which is acceleration due to gravity. . Further, the area shown in (e) on the right side is a waveform during free fall, and since the influence of gravity on the Y axis is eliminated, 0 G is also output on this axis. In the video camera of this embodiment, when the outputs of the three axes become 0.4 G or less at the same time, it is determined that a free fall is in progress, and the recording head is connected to the hard disk drive (HDD) as shown in FIG. As shown in b), control is performed so that the head holding mechanism provided outside the disk surface called a ramp is retracted. Thereby, the contact of the disk and the head due to the impact after dropping can be prevented.

  FIG. 4 is a diagram illustrating an example when the video camera of the present embodiment is dropped with the power cable connected thereto.

  The figure shows a situation where the fall starts from the state of being placed on a desk or the like, the power cable is pulled upward immediately after the fall starts, and the main body rotates. In this case, the output of the three-dimensional acceleration sensor is in a state of free fall immediately after dropping, as shown in FIG. 4 (c), but at the moment when it is pulled by the power cable, it is shown in FIG. 4 (a). As shown in FIG. 4D, rotation is started, and centrifugal force is exerted on the X axis close to the axial direction connecting the center of gravity and the power supply terminal, so that an output as shown in FIG. 4D is observed. For this reason, although it is in the free fall, it will not be below 0.4G, and it will be in the state where the judgment of free fall was canceled.

  In the video camera of the present embodiment, when the connection of the power cable is detected, the threshold value for determining that only the X axis is free fall is set to 0.8 G, which is larger than 0.4 G, and at the same time the X axis is When the acceleration of 0.8 G or less and the other two axes, the Y axis and the Z axis, detect 0.4 G or less, it is determined that the main body is falling. As a result, free fall can be detected without being affected by the centrifugal force caused by the rotation.

  FIG. 5 is a diagram showing an example when the video camera is dropped with the video cable connected to the video terminal of the present embodiment.

  Fig. 5 (a) is a view of the video camera as viewed from above. The video camera starts to fall from a state where it is placed on a desk or the like, and immediately after the fall starts, the video cable is pulled upward and the main body rotates. Shows the situation. In this case, the output of the three-dimensional acceleration sensor is in a state of free fall immediately after dropping, as shown in FIG. 5C, but at the moment when it is pulled by the power cable, it is shown in FIG. As shown in FIG. 5D, rotation is started, and centrifugal force is exerted on the X axis and Z axis which are close to the axial direction connecting the center of gravity and the power supply terminal, so that an output as shown in FIG. 5D is observed. For this reason, although it is in the free fall, the state where the determination of the free fall which is not 0.4G or less is canceled occurs.

  In the video camera of the present embodiment, when the connection of the video cable is detected, the threshold value for determining the free fall of the X axis and the Z axis is set to 0.8 G, which is larger than 0.4 G, and at the same time, When the X axis and the Z axis detect acceleration of 0.8 G or less and the other axis, the Y axis, detects 0.4 G or less, it is determined that the main body is falling.

  The video camera according to the present embodiment is configured to determine that the main body is free-falling when an acceleration value that is simultaneously below a predetermined threshold value is detected for each of the X axis, the Y axis, and the Z axis. However, in this method, when the three axes fall in an intermediate direction that is orthogonal to each other, the apparent predetermined value becomes large. Therefore, the X-axis, Y-axis, and Z-axis acceleration values are vector-combined. The scalar amount may be less than a predetermined value. In this configuration, when a large-capacity battery is detected, the output of the X axis that is affected by the centrifugal force is multiplied by a factor of 0.5, and the value is combined with the other Y axis and Z axis outputs, By determining that the main body is free-falling when the amount of the scalar becomes 0.4, it is possible to detect free-fall without being affected by the centrifugal force due to rotation.

  Also, when connecting the cable, it is assumed that there are many cases where the user will fall on the cable and drop the main body, and the X-axis and Y-axis other than the Y-axis, which is the vertical direction, will change significantly. In the case where there is a head, the head is determined to be in a free fall, and the recording head is provided outside the disk surface called a ramp as shown in FIG. 3B with respect to the hard disk drive (HDD). You may add the structure which controls to retract | save to a holding | maintenance mechanism.

It is a block diagram of the video camera of an Example. It is a figure which shows the outline | summary of the video camera of an Example. It is a figure which shows the detail of the hard-disk drive of an Example. It is a figure which shows the outline | summary of the video camera of an Example. It is a figure which shows the outline | summary of the video camera of an Example. It is a figure which shows the output by a three-dimensional acceleration sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Shooting lens 102 Aperture 103 Image sensor 104 CDS / AGC
105 Digital Signal Processing Circuit 106 Frame Memory 107 Pixel Number Adjustment Circuit 108 Image / Audio Data Bus 109 Microphone 110 Amplifier 111 A / D Converter 112 Liquid Crystal Display 113 Liquid Crystal Driver 114 MPEG2 Codec 115 Stream Buffer 116 Video Output Terminal 117 NTSC Encoder 118 Disk Driver 119 Hard disk drive 120 USB terminal 121 USB controller 122 Operation key 123 Main microcomputer 124 RAM
125 EEPROM
126 Control bus 127 3D acceleration sensor 128 Cable connection detection switch

Claims (9)

An acceleration detection means for detecting accelerations in three axial directions orthogonal to each other, a free fall determination means for determining whether or not the main body is in a free fall state based on an output value of the acceleration detection means, and a free fall determination means Depending on the judgment result, the recording medium impact protection means for protecting the recording medium for recording and reading data from the impact and the power supply terminal for connecting the power cable for supplying the power to operate the main body, or an analog signal is input or output In a portable electronic device having an analog signal terminal for connecting an analog signal cable for performing or a digital signal terminal for connecting a digital signal cable for inputting or outputting a digital signal,
Connection cable detection means for detecting whether the cable is connected to the power supply terminal, the analog signal terminal or the digital signal terminal, respectively, and depending on the detection result of the detected cable detection means, the free A portable electronic device characterized in that a threshold value of an output of the acceleration detecting means for determining that the fall determining means is in a free fall state is changed. The portable electronic device according to claim 1,
The free fall determination means is for determining that the main body is in a free fall state when the output values in the three directions by the acceleration detection means simultaneously become equal to or less than a threshold value, and the cable detection means When it is detected that the cable is connected to a predetermined terminal, the acceleration detecting means close to the axial direction connecting the position of the terminal to which the cable is connected and the position where the acceleration detecting means is mounted. A portable electronic device, characterized in that an output threshold value for determining free fall in the axial output is large. The portable electronic device according to claim 1,
The free fall determination means determines that the main body is in a free fall state when the absolute value of the vector composite value obtained by vector synthesis of the outputs in the three directions of the acceleration detection means is not more than a predetermined value. When the cable detection means detects that the cable is connected to a predetermined terminal, the position of the terminal to which the cable is connected is connected to the position where the acceleration detection means is mounted. An absolute value of a vector synthesized value obtained by vector synthesis of a value obtained by multiplying an axial output of the acceleration detecting means close to the axis by a coefficient less than 1 and an output in the other two directions. A portable electronic device, which is determined to be in a free-fall state when it becomes a predetermined value or less. An acceleration detection means for detecting accelerations in three axial directions orthogonal to each other, a free fall determination means for determining whether or not the main body is in a free fall state based on an output value of the acceleration detection means, and a free fall determination means Depending on the judgment result, the recording medium impact protection means for protecting the recording medium for recording and reading data from the impact and the power supply terminal for connecting the power cable for supplying the power to operate the main body, or an analog signal is input or output In a portable electronic device having an analog signal terminal for connecting an analog signal cable for performing or a digital signal terminal for connecting a digital signal cable for inputting or outputting a digital signal,
It has connection cable detection means for detecting whether the cable is connected to the power supply terminal, the analog signal terminal or the digital signal terminal, respectively, and it is detected that the cable is connected by the connection cable detection means. If the change in acceleration is observed for one of the two axes other than the vertical axis among the accelerations in the three axis directions, the free fall determination means determines that the free fall state is in the free fall state. A portable electronic device. The portable electronic device according to any one of claims 1 to 4,
A portable electronic device characterized in that a signal handled by the digital signal cable is encoded video / audio data superimposed after the analog video signal and the analog audio signal are digitized and compressed and encoded. It is a portable electronic device in any one of Claims 1-5, Comprising:
A portable electronic device characterized in that the signal handled by the digital signal cable is uncompressed stream data of encoded video and audio superimposed by digitizing the analog video signal and analog audio signal. The portable electronic device according to any one of claims 1 to 6,
A signal handled by the digital signal cable is a control signal for controlling the portable electronic device from the outside. It is a portable electronic device in any one of Claims 1-7,
The recording medium is a hard disk drive, and the drive includes a ramp that is an arm holding mechanism that protects the magnetic head and an arm that supports the magnetic head when the magnetic head is outside the disk. When the free fall detection means detects a free fall state of the main body, the recording medium protection means is operated to forcibly move the magnetic head to the ramp to be held by the ramp. Portable electronic devices. It is a portable electronic device in any one of Claims 1-8, Comprising:
A data buffer for temporarily storing data to be recorded on the recording medium, and storing the recording data in the data buffer while the recording medium protection means is operating and data recording on the recording medium is stopped Is a recording device characterized by continuing.

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