JP4673810B2 - Portable video display device - Google Patents

Description

  The present invention relates to a portable video terminal device, and more particularly to a video display technique thereof.

  In recent years, miniaturization and low power consumption of video display devices have progressed, and portable video display devices have become widespread. In addition, ISDB-T (Integrated Services Digital Broadcasting for Terrestrial) terrestrial digital one-segment broadcasting service that has strong multipath ghost resistance and strong error correction, and has strong characteristics for mobile mobile reception, has also started.

  This one-seg broadcast receiving terminal can watch clear broadcast video even while walking, in a running train, car, or walking, so it has become possible to watch TV while moving, which was difficult in the past.

  However, video viewing by a portable video display device on a traveling vehicle represented by a train or the like is because the viewer himself / herself holds the portable video display device by hand, so that the broadcast video can be viewed on an unstable and vibrating display screen. Will do. Watching video in this way can cause symptoms called “video sickness” similar to motion sickness.

  As a measure to improve the shaking of the image due to the unstable and vibrating display screen, when the spatial position of the image display unit moves, so that the spatial display position of the image seen by the viewer does not change, An image display apparatus having a configuration as shown in FIG. 12 that moves the display position of an image on the image display in a direction opposite to the vibration acceleration is disclosed (for example, see Patent Document 1).

According to the description of Patent Document 1, as shown in FIG. 12, the image stored in the image data storage unit 127 is moved in the opposite direction to the acceleration detected by the longitudinal accelerometer 123 and the lateral accelerometer 124, thereby Even if the display device 121 vibrates, the image is spatially stable and the visibility is improved. Furthermore, a configuration is also disclosed in which a high-pass filter provided in the display position correction calculation unit 125 is passed through the outputs of the accelerometers 123 and 124 to perform display position correction 128 only for high-speed vibrations that are difficult to follow with human eyes. ing.
JP 07-36421 A, "Image display device"

  In the image display device described in Patent Document 1, the vibration of the image display device 121 is detected, and the image corresponding to this is detected to compensate for the image shake caused by the vibration of the image display device 121. It is possible to do.

However, in order to cancel the image shake caused by vibration, the accelerometers 123 and 124 must be capable of high-speed detection and have a highly sensitive position sensor, and the display position correction calculation unit 125 can perform high-speed computation. As for processing performance, the display position correction driving unit 128 needs high-speed drawing processing performance. For this reason, when the invention described in Patent Document 1 is applied to a portable video display device in order to prevent “video sickness”, the following problems occur.
1) Increase in volume and weight of portable video display device due to the installation of a high-speed, high-sensitivity position sensor, a high-speed arithmetic processing device, and a high-speed drawing processing device, and an increase in cost.
2) Increase in power consumption and cost due to high-speed arithmetic processing devices and high-speed drawing processing devices.

  An object of the present invention is to provide an image display device that effectively reduces “video sickness” with a simple configuration.

  The image display device according to the present invention includes means for extracting vibrations that cause image motion that is likely to cause image sickness from the vibrations, and canceling the image motions based on this. This eliminates the need to use a high-speed arithmetic processing device, a high-speed drawing processing device, and the like that cause an increase in volume and weight of the portable video display device and an increase in power consumption.

  In order to solve the above-mentioned problems, the portable video display device of the present invention detects the movement of the device itself, and the CFF (Critical Flicker Frequency) of the blinking frequency that human perception can be perceived from the detected movement of the device. It is characterized by extracting a vibration component of 30 Hz or less and correcting the image display position in a direction to correct the vibration.

  Furthermore, the portable video display device according to the present invention is characterized in that the video display position is changed in a direction in which a rotational motion with a low frequency of, for example, 30 Hz or less is extracted from the detected motion and corrected.

  Furthermore, the portable video display device according to the present invention is characterized in that the motion vector of the entire screen of the moving image to be displayed is detected and the video display position is changed in comparison with the motion of the device itself.

  The portable video display device of the present invention extracts a slow vibration component from the movement of the device itself, and changes the video display position in a direction to correct the movement. In particular, the slow rotational motion is a motion that easily causes video sickness, and can efficiently reduce video sickness. Furthermore, since a low-frequency vibration component is corrected, it is possible to realize a portable video display device that does not require high speed, arithmetic processing, or drawing processing.

(First embodiment)
The best mode for carrying out the portable video display device of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration example of a portable video display device according to this embodiment. As shown in FIG. 1, the portable video display device according to the present embodiment includes an antenna 11 that receives, for example, a digital terrestrial one-segment broadcasting radio wave, a receiver 12, and a motion detector 13 that detects the motion of the device itself. A correction vibration extraction unit 14 that extracts a vibration component to be corrected from the detected motion, a display position change processing unit 15 that changes a display position of the broadcast video in a direction to correct the extracted vibration component, and a video display And a display unit 16. And the said structure is accommodated in the upper housing | casing 21 and the lower housing | casing 22 which are shown, for example in the apparatus general-view figure of FIG. The upper housing 21 is provided with a display screen 16 and an antenna 11. The lower casing 22 is provided with operation buttons 23 and the like, and the viewer can hold the lower casing and watch the broadcast video displayed on the display screen 16 while pressing the operation buttons 23 when necessary. . For example, in the mobile phone shown in FIG. 2, when viewing digital broadcasting, the upper casing 21 can be horizontally long, and in the case of general calls and mails, it can be vertically long. In the case of landscape, that is, the vibration component may be corrected only when viewing a digital broadcast such as one segment. In this case, as correction cases, when it is detected that a digital broadcast is being viewed, when a planar movement of a mobile phone is detected (when a user's movement is detected by GPS or the like), a correction process is started. The correction may be performed only when the user's operation is performed.

  With reference to FIG. 3, an example of a reception process of terrestrial digital one-segment broadcasting will be described. The digital broadcast radio wave received by the antenna 11 is tuned to the broadcast channel desired by the user by the tuner 31 in the receiving unit 12. More specifically, the RF signal from the antenna 11 is amplified, and an IF signal obtained by converting the frequency of the broadcast channel desired by the user into a predetermined frequency is output. The IF signal output from the tuner 31 is subjected to OFDM demodulation processing in an OFDM (Orthogonal Frequency Division Multiplexing) demodulator 32 to output TS data (Transport Stream).

  More specifically, the input IF signal is A / D converted and then quadrature detected to be converted into a baseband symbol. Thereafter, the data is demodulated by symbol synchronization, a frame synchronization unit, and FFT processing. Furthermore, error correction processing such as deinterleaving processing, Viterbi decoding processing, and RS decoding processing is executed, and TS data is output. The TS data output from the OFDM demodulator 32 is subjected to demax processing and decoding processing in the TS processing unit 33, and video data and audio data are output. The video data is output to the display position changing unit 15, and the audio data is output from the speaker.

  The motion detection unit 13 detects the motion of the mobile terminal itself and outputs the detection result to the corrected vibration extraction unit 14. The motion detection unit 13 is provided with an angular velocity sensor that detects rotational motion. As a specific example of a miniaturized angular velocity sensor that can be mounted on a portable terminal according to this embodiment, a piezoelectric vibration gyro sensor, an inertial sensor using the Coriolis effect, or the like can be used.

  The motion detection unit 13 is arranged at the center of the display screen unit 16 as indicated by the hatched portion in FIG. When the motion detection unit 13 is arranged in the lower housing 22, the motion of the terminal detected by the motion detection unit and the motion of the display screen 16 do not match, so correction processing needs to be performed. Further, when the upper housing 21 is provided with a mechanism that is hingedly connected to the lower housing 22 and rotates, the correction process is further complicated. By arranging the motion detection unit 13 at the center of the display screen 16 as in the present embodiment, the rotational motion of the terminal detected by the motion detection unit 13 matches the rotational motion of the display screen, and the upper housing 21 Even when a mechanism is provided that is hinged to the lower housing 22 and rotates, there is an advantage that it is not necessary to perform correction processing.

  In the present embodiment, an angular velocity sensor is used as the motion detection unit 13, but an acceleration sensor that detects vertical and horizontal motions relative to the display screen, for example, a piezoresistive sensor manufactured by MEMS technology using a Si material or an electrostatic sensor. It is also possible to use a capacitive type, a magnetic sensor for detecting a magnetic change, or the like. In addition, a CCD camera that captures the viewer is provided near the display screen, and the movement of the viewer's eyes is detected by analyzing the video captured by the CCD camera, and the position of the display screen and the viewer's eyes is determined. It is also possible to detect changes in the relationship and movement.

  The processing contents in the corrected vibration extracting unit 14 will be described with reference to FIG. The vibration detection result detected by the motion detector 13 is converted into digital data by the A / D converter 41, and only the vibration component in the low frequency band is extracted by the low-pass filter. As shown in FIG. 5A, the low-pass filter 42 includes an IIR filter (Infinite-duration Impulse Response Filter) including an adder 51, a delay unit 52, and a multiplier 53, and FIG. As shown in B), a digital filter such as an FIR filter (Finite Impulse Response Filter) including an adder 51, a multistage delay unit 52, and a multiplier 53 can be used. The IIR filter is a low-pass filter that delays the input signal from the A / D conversion unit 41 by a delay unit 52 for a predetermined time, feeds back the signal by the adder 51, multiplies the coefficient K by the multiplier 53, and outputs the result. The FIR filter sequentially delays the input signal from the A / D converter 41 by each delay unit 52-1, 52-2, and outputs the output of each delay unit 52-1, 52-2 to the multiplier 53-1, 53- 2, a low-pass filter that multiplies coefficients K1, K2, and K3 by 2,53-3, adds the multiplication results by an adder 51, and outputs the result. Although not particularly illustrated, the output of the motion detector 13 may be converted into a digital signal after extracting a low-frequency vibration component with an analog low-pass filter composed of analog elements such as L, C, and R.

  In the present embodiment, as a characteristic of the low-pass filter, for example, a low frequency component of 6 Hz to 10 Hz or less is extracted. The filter characteristics of the low-pass filter 32 are set with coefficients K, K1, K2, and K3 for digital filters, and set with the LCR time constant for analog filters, but various designs can be made by using filter design simulation. Is possible. Information on the slow rotational vibration of the mobile terminal itself is sent to the display position change processing unit 15 by the motion detection unit 13 and the correction vibration extraction unit 14 described above.

  In the display position changing process 15, the display position of the video is changed in a direction to cancel the input vibrational motion. Specifically, when the terminal shown in FIG. 7 is rotated by Δd (62) from the assumption that the cross image 61 is displayed on the display screen 16 shown in FIG. That is, the display position is reversely rotated by Δ−d (63). When the display position is rotated here, as shown in FIG. 8, a state (FIG. 8A) in which a part 81 protrudes from the display screen 16 area and cannot be displayed occurs. This can be solved by setting the limit angle ΔL63 at which the image protrudes to the limit value of the correction amount by setting the image size to be smaller than the size of the display screen 16 (FIG. 8B).

  With the above configuration, it is possible to correct a slow rotational movement that easily causes video sickness, and to realize a portable video display device that can efficiently reduce video sickness.

(Second Embodiment)
A portable video display device according to the second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a functional block diagram showing a configuration example according to the second embodiment of the present invention. The difference from the first embodiment is that the function blocks indicated by bold lines, that is, the entire screen motion detection unit 91 that detects the motion component of the moving image to be displayed, the corrected vibration extraction unit 14 and the entire screen motion detection unit 91 And a motion comparison unit 92 that compares the motion information and calculates the correction amount. The same reference numerals are used for the same functions other than that, and the description thereof is omitted.

  The entire screen motion detection unit 91 calculates a motion vector of the entire screen to be displayed. FIG. 10 is a diagram illustrating a method of calculating the motion vector of the entire screen. For example, the detection areas 101 are arranged at four places on the display screen 16, and the partial motion vectors 102 in the respective detection areas 101 are calculated.

  The detection process of the partial motion vector 102 is calculated by correlating the image signal within each detection area to indicate where the representative pixel of the previous screen (previous frame) has moved on the current screen (current frame). Thereafter, the motion vector 103 of the entire screen can be detected by arithmetically averaging the partial motion vectors 102 of each detection region 101. Using the low-pass filter 42 described in the first embodiment, a slow vibration component of 6 to 10 Hz or less is extracted from the motion vector 103 of the entire screen and output to the motion comparison unit 92.

  The processing content of the motion comparison unit 92 will be described with reference to FIG. The motion comparison unit 92 compares the two vectors of the input motion information of the terminal itself and the motion information of the moving image to be displayed, and outputs the display screen correction amount to the display position change process 15. Specifically, as shown in FIG. 11, in a state where the image rotated at Δi is displayed on the display screen 16 (FIG. 11A), the terminal is only Δd in the same direction as the image rotation Δi. In the case of rotation (FIG. 11B), the motion comparison unit 92 rotates the display position by Δi + Δd (112). On the other hand, when the terminal rotates Δd in the opposite direction to the image rotation Δi (FIG. 11C), the motion comparison unit 62 rotates the display position by Δi−Δd.

  With the above configuration, it is possible to further reduce the motion sickness by changing the video display position based on the motion of the moving image to be displayed and the motion of the terminal as compared with the first embodiment.

  As described above, the portable video display apparatus according to the present embodiment extracts a slow vibration component from the movement of the apparatus itself, and changes the video display position in a direction to correct the movement. In particular, the slow rotational motion is a motion that easily causes video sickness, and can efficiently reduce video sickness.

  Furthermore, since the low-frequency vibration component is corrected, there is no need for high speed, arithmetic processing and drawing processing, and the cost of the portable video display device can be reduced. In addition, an increase in power consumption of the portable video display device based on the correction can be suppressed.

  The present invention is applicable to a portable video display device.

1 is a functional block diagram illustrating a configuration example of a portable video display device according to a first embodiment of the present invention. 1 is an overview of a portable video display device according to the present embodiment. It is a block diagram which shows the structural example of the receiving part of the portable video display apparatus by this Embodiment. It is a block diagram which shows the structural example of the correction | amendment vibration extraction part of the portable video display apparatus by this Embodiment. It is a block diagram which shows the low-pass filter used for the portable video display apparatus by this Embodiment. It is a figure which shows the processing content in the display position change part used for the portable video display apparatus by this Embodiment with the motion of a display part. It is a figure which shows the processing content in the display position change part used for the portable video display apparatus by this Embodiment with the motion of a display part. It is the figure which showed the processing content of the display position change part used for the portable video display apparatus by this Embodiment with the movement of a display part. It is a functional block diagram which shows the example of 1 structure of the portable video display apparatus by the 2nd Embodiment of this invention. It is a figure which shows operation | movement of the whole screen motion detection part of the portable video display apparatus by this Embodiment on a display screen. It is a figure which shows operation | movement of the movement comparison part in the portable video display apparatus by this Embodiment by the movement of a display part. It is a block diagram which shows the structural example of the portable video display apparatus of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Antenna, 12 ... Reception part, 13 ... Motion detection part, 14 ... Correction vibration extraction part, 15 ... Display position change process part, 16 ... Display part, 21 ... Upper housing | casing, 22 ... Lower housing | casing, 31 ... Tuner 32 ... OFDM demodulation unit, 33 ... TS processing unit, 41 ... A / D conversion unit, 42 ... low pass filter, 51 ... adder, 52 ... delayor, 53 ... multiplier, 54 ... filter coefficient, 61 ... display video , 62 ... terminal rotation, 63 ... display position rotation, 81 ... area that protrudes from the screen, 9 ... entire screen motion detection unit, 92 ... motion comparison unit, 101 ... detection region, 102 ... partial motion vector, 103 ... entire screen Motion vector, 111 ... image rotation, 112 ... terminal rotation, 113 ... display position rotation, 121 ... image display device, 122 ... display unit, 123 ... vertical accelerometer, 124 ... lateral accelerometer, 125 ... display position correction calculation unit , 126 ... display content control section, 127 ... image data storage section, 128 ... display position correction drive section.

Claims (6)

Based on the signal from one of the angular velocity sensor provided at the center of the image display section, an image display unit rotational movement detecting section for detecting a rotational movement of said image display unit,
Based on the rotation movement of the image display section detected by the image display section rotation movement detection section, the image display position on the image display section is changed in a direction to cancel the rotation of the display image caused by the rotation movement of the image display section. A portable image display device comprising: an image display position changing unit for correcting the image display position only for a rotational motion of 30 Hz or less.   Considering the fact that rotating the display position partially prevents the display screen area from being displayed, the display video size is set to be slightly smaller than the display screen size, and the limit angle at which the image protrudes is the limit of the correction amount. The portable image display device according to claim 1, wherein the portable image display device is set to a value. A display image motion vector detection unit that extracts a motion vector of the entire screen of the display video image;
Of the motion vectors of the entire screen of the displayed moving image, the rotational motion vector having a vibration component of 6 to 10 Hz is compared with the rotational motion vector of the image display unit of 30 Hz or less, and the combined vector of the two rotational motions A motion comparison unit that calculates a correction amount so as to cancel out
A display position changing unit that changes the display position of the image based on the correction amount from the motion comparison unit;
The portable video display device according to claim 1 or 2, further comprising:   It is characterized in that detection areas are arranged at a plurality of locations on a display screen, partial motion vectors in each detection area are calculated, and a motion vector of the entire screen is detected by arithmetic averaging of the partial motion vectors in each detection area. The portable video display device according to claim 3.   A terrestrial digital broadcast receiver comprising the portable video display device according to any one of claims 1 to 4.   A portable terminal device comprising the terrestrial digital broadcast receiver according to claim 5.

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