JP2012089994A - Stereoscopic image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stereoscopic image display device in which when an image is displayed in a reduced size to adjust a parallax amount, realizes image luminance and cross talk performance in good balance.SOLUTION: An image reduction circuit 12 reduces a stereoscopic image by a predetermined reduction rate. An image display circuit 13 displays the reduced stereoscopic image on a display part 14. A shutter spectacle control circuit 15 supplies an opening/closing timing signal to shutter spectacles 16. The image display circuit 13 limits a scanning time at the display part 14 to the display area of the reduced stereoscopic image, and a shutter spectacle control circuit 15 increases the opening time of the shutter spectacles 16 by the reduced portion of the scanning time at the display part 14.

Description

  The present invention relates to a stereoscopic image display apparatus, and more particularly to a stereoscopic image display apparatus using a shutter glasses method.

  Conventionally, stereoscopic image display methods have been studied and put into practical use in many fields that handle images such as photographs, movies, and televisions. Among them, a stereoscopic image display method called a parallax type is a method in which image light with parallax is separately incident on the left and right eyes of the viewer, and the viewer recognizes the stereoscopic image by giving the parallax. Is. Furthermore, as a parallax type realization method, there is a glasses method, and a method using shutter glasses and a method using polarized glasses are known.

  In the shutter glasses method, for example, a left-eye image and a right-eye image are alternately displayed on a display screen for each frame. As a result of the viewer viewing this image through shutter glasses composed of liquid crystal, for example, which are alternately opened and closed, the left eye image is viewed only by the left eye and the right eye image is viewed only by the right eye. Can be recognized as a stereoscopic image.

  When the viewer views a stereoscopic image, if the parallax, which is a shift between corresponding points of the left and right images, exceeds a certain range, the images of both eyes will not be fused. In other words, if the parallax is excessive, the image appears as a double image even when glasses are used, and stereoscopic viewing becomes impossible. As a countermeasure for this, for example, Patent Document 1 describes that, in order to adjust the parallax amount of a stereoscopic image, image processing for changing the parallax amount of the stereoscopic image is performed by enlarging or reducing the image and displaying the image.

JP-A-2005-73013

  In the shutter glasses method, the left-eye image and the right-eye image are alternately displayed for each frame, but it is important to control the opening / closing timing of the shutter glasses. While the shutter glasses are open for a period within each image display period, the image display period for each frame is from one frame period to the scanning time of a display element (for example, a liquid crystal element) in the screen and the display element. The time obtained by subtracting the response time is the effective display time of the entire screen. Therefore, as the number of elements in the screen increases (the resolution increases), the scanning time increases and the effective display time decreases. As a result, the time during which the shutter is open is shortened and the image brightness during viewing is reduced.

On the other hand, it is assumed that the shutter opening time is longer than the effective image display period in order to increase the image brightness. When the shutter is opened at an early timing, the image of the previous frame remains, and when the shutter is closed at a later timing, the image of the next frame starts to appear. The front and rear frames are images for the opposite eye, and should not be viewed with the originally intended eye. In this way, a state where an image that should not be seen with the originally intended eye is visible is crosstalk. On a screen with a lot of crosstalk, the image appears double, which promotes adverse health effects such as image sickness, eye strain, and irritation.
As described above, when a stereoscopic image is viewed using the shutter glasses method, it is difficult to achieve both because the image brightness and the crosstalk performance are in a trade-off relationship.

  On the other hand, if the parallax of the stereoscopic image is excessive, the image appears as a double image, and the original stereoscopic view cannot be performed. As described in Patent Document 1, the amount of parallax can be optimally adjusted by enlarging or reducing the image. Thus, no particular consideration was given to optimizing the shutter timing when reducing the screen for adjusting the parallax amount.

  An object of the present invention is to provide a stereoscopic image display device that realizes a good balance between image luminance and crosstalk performance when an image is reduced and displayed for parallax amount adjustment.

  The present invention relates to an image reduction circuit that reduces a stereoscopic image at a predetermined reduction ratio in a stereoscopic image display device that displays a reduced stereoscopic image on a display unit and views the displayed stereoscopic image with shutter glasses. And a shutter glasses control circuit for supplying an opening / closing timing signal to the shutter glasses, and the image display circuit displays a stereoscopic image display region with a reduced scanning time in the display unit. However, the shutter glasses control circuit is configured to increase the opening time of the shutter glasses by the reduction of the scanning time in the display unit.

  Here, the image reduction circuit reduces the stereoscopic image at a predetermined reduction rate according to an operation instruction from the remote controller or according to the parallax amount of the stereoscopic image to be displayed.

  Further, the image display circuit moves and displays the reduced stereoscopic image display position on the display unit according to an operation instruction from the remote controller or according to the occurrence of crosstalk of the stereoscopic image to be displayed.

  According to the present invention, it is possible to provide a stereoscopic image display device that realizes a good balance between image luminance and crosstalk performance when an image is reduced and displayed.

The block block diagram which shows embodiment of the three-dimensional image display apparatus by this invention. The figure which shows reduction of the display screen by the image reduction circuit 12. FIG. The figure which shows the timing of the drive signal of the image display part and shutter spectacles in a full screen display (comparative example). FIG. 6 is a diagram illustrating timings of driving signals for an image display unit and shutter glasses in a reduced screen display (Example 1). FIG. 6 is a diagram illustrating timings of driving signals for an image display unit and shutter glasses for reducing crosstalk (Example 2).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a stereoscopic image display apparatus according to the present invention.
The input terminal 10 receives an image signal 100 of a stereoscopic image. The image processing circuit 11 performs conversion to a field sequential method signal required for the shutter glasses method, image quality improvement processing, and the like, and creates a stereoscopic image display signal 101. The image reduction circuit 12 receives an instruction (screen reduction rate setting signal 105) from the remote controller 17 and converts the image signal 101 into a set reduction rate. The image display circuit 13 outputs the reduced image signal 102 to the display unit 14 such as a liquid crystal panel, and displays the reduced image. At that time, the display position of the reduced image in the display unit 14 can be moved. Further, the image display circuit 13 sends an image synchronization signal 103 to the shutter glasses control circuit 15. The shutter glasses control circuit 15 supplies the shutter glasses 16 with a shutter drive signal 104 for controlling the opening / closing timing of the shutter. The shutter glasses 16 are composed of, for example, a liquid crystal shutter, and perform an opening / closing operation of the shutter at an appropriate timing in synchronization with the left-eye image and the right-eye image displayed on the display unit 14. The viewer views the stereoscopic image using the shutter glasses 16.

  When the viewer sees the stereoscopic image displayed on the display unit 14 and feels that the parallax is excessive, the viewer operates the remote controller 17 to send the screen reduction ratio setting signal 105 to the image reduction circuit 12 to optimize the parallax. To adjust the amount of parallax. In addition, the viewer operates the remote controller 17 to send a display position setting signal 106 to the image display circuit 13 to adjust where the reduced image is displayed on the screen of the display unit 14. Further, the viewer can adjust the shutter timing by operating the remote controller 17 and sending the shutter timing correction signal 107 to the shutter glasses control circuit 15. By adjusting the display position of the reduced image or adjusting the shutter timing, it is possible to reduce crosstalk as described later.

  In the present embodiment, the viewer operates the remote controller 17 while viewing the displayed image, and adjusts the parallax amount and the crosstalk to be optimal. Instead of this, the image display device itself may have a function of detecting the amount of parallax and crosstalk. The amount of parallax is estimated by measuring the shift between corresponding points of the left and right images, and crosstalk is obtained by calculating the reaction speed of the liquid crystal by measuring the switching timing of the display screen. The image reduction circuit 12, the image display circuit 13, and the shutter glasses control circuit 15 are controlled from these detection results, and the adjustment can be made automatically.

  FIG. 2 is a diagram showing the reduction of the display screen by the image reduction circuit 12. On the display unit 14, the screen 20 is a display area when the entire screen is displayed without being reduced, and the screen 21 is a display area when the screen is reduced and displayed. In the case of reduced display, non-display areas 22a, 22b, 22c, and 22d exist around the screen 21. These non-display areas may be equally distributed to the top, bottom, left, and right of the screen 21, or may be displayed with a bias in the top, bottom, left and right directions under the control of the image display circuit 13. In the non-reduced screen 20, the scanning start point is A and the end point is B, but in the reduced screen 21, the scanning start point is P and the end point is Q as will be described later.

  By reducing the display screen, the shift between corresponding points of the left and right images of the stereoscopic image is reduced. That is, when the amount of parallax between the left and right images is excessive, the amount of parallax is reduced by reducing the screen, and the viewer can view the stereoscopic image normally and comfortably.

  FIG. 3 is a diagram showing timings of driving signals for the image display unit and the shutter glasses in full screen display (screen 20 in FIG. 2) for comparison. The horizontal axis represents time, and the vertical axis represents the relationship between the scanning position signal of the image display unit (liquid crystal panel) and the transmittance of the left and right shutter glasses (liquid crystal shutter). The transmittance On is the shutter open state, and the transmittance Off is the shutter closed state.

  In the image display unit, the left-eye image (L) and the right-eye image (R) are F1 (L), F2 (R), F3 (L), F4 (R),. Displayed alternately. When the drive frequency is 120 Hz, the time t0 allocated to each frame is 1/120 sec. In each frame, first, writing 31 is performed in order from the top of the screen (position A in FIG. 2) according to the image signal, and scanning is performed to the bottom of the screen (position B in FIG. 2). The time required for scanning from the upper part (A) to the lower part (B) of this screen is the “in-screen writing time t1”. Furthermore, a period 32 from when the image signal is received until the liquid crystal display element (display cell) actually reacts is the “cell response time t2”. The added value of the “in-screen writing time t1” and the “cell response time t2” is the time required for switching from the image of the previous frame to the image of the frame. The time obtained by subtracting the “in-screen writing time t1” and the “cell response time t2” from the time t0 assigned to each frame is the “display time t3” of the image of the frame (t3 = t0− (t1 + t2). ).

  On the other hand, the shutter eyeglass drive signals are indicated by a left-eye shutter 41L and a right-eye shutter 41R. Ideally, the time t4 at which one shutter of the shutter glasses is opened (transmittance On) and the timing thereof are synchronized with the display time t3 on the image display unit. This is because if the shutter is opened earlier than this, the image of the previous frame remains, and the image of the next frame starts to appear at a later timing. Since the preceding and following frames are images for the opposite eye, mixing these images causes crosstalk. In order to avoid crosstalk, it is necessary to completely close the shutter between “in-screen writing time t1” + “cell response time t2” and to open the shutter only for a time t4 equal to “display time t3”. There is.

  In order to avoid crosstalk in this way, the opening time t4 of the shutter glasses is uniquely determined by the “in-screen writing time t1” and the “cell response time t2” of the display unit. The opening time t4 is about 2 to 4 msec. When the resolution and frame rate of the display unit are increased, the shutter opening time t4 is further shortened. As a result, the luminance of the image visually recognized on the display unit is lowered. On the contrary, if the image brightness is improved, the crosstalk deteriorates, and the two are in a trade-off relationship.

  In the embodiment described below, a configuration for improving the image luminance visually recognized on the display unit without deteriorating the crosstalk in the reduced screen (screen 21 in FIG. 2) will be described.

FIG. 4 is a diagram illustrating timings of driving signals for the image display unit and shutter glasses in the reduced screen display. The description of the horizontal axis and the vertical axis is the same as in FIG.
In this embodiment, when the screen is displayed in a reduced size, the scanning range is limited to the display area 21 as shown in FIG. 2, the scanning start point is P, and the end point is Q. That is, the time for scanning the non-display areas 22a, 22b, 22c, and 22d becomes unnecessary, and the in-screen writing time is shortened from t1 to t1 ′. The cell response time t2 does not change. As a result, the display time t3 ′ becomes t3 ′ = t0− (t1 ′ + t2), which is increased by the reduction of the scanning time. By generating an opening / closing timing signal of the shutter glasses in synchronization with the display time t3 ′, the shutter opening time becomes t4 ′. The shutter opening time t4 ′ is longer than the shutter opening time t4 (shown by a dotted line) in the case of FIG. 3 shown as a comparative example. As a result, the viewer's visual brightness can be increased without deteriorating the crosstalk. Note that the display time t3 ′ and the shutter opening time t4 ′ do not necessarily have to be equal. In practice, the luminance performance can be further improved by increasing the shutter opening time t4 ′ within a range where crosstalk is allowed.

  Although FIG. 2 shows the case where the reduced screen 21 is displayed at the center of the display unit 14, the reduced screen can be displayed in the vertical and horizontal directions by the image display circuit 13. In this case, the scanning periods P to Q of the reduced screen are shifted on the time axis, and the timing of the display time t3 'and the shutter opening time t4' may be shifted accordingly.

  The operation of this embodiment is realized by the following flow. The viewer operates the remote controller 17 to instruct image reduction (sends the screen reduction ratio setting signal 105), and adjusts the stereoscopic image to be viewed to have an optimum amount of parallax (or the device itself measures the amount of parallax. It is also possible to reduce the image automatically). The image reduction circuit 12 reduces the screen (image) at the instructed reduction rate, and the image display circuit 13 generates a display drive signal for the reduced screen (image) and causes the display unit 14 to display the image. Normally, a reduced screen is displayed at the center of the display unit 14, but the viewer can move the display position in the vertical and horizontal directions by operating the remote controller 17 (sends a display position setting signal 106). The image display circuit 13 sends an image synchronization signal 103 indicating a display time t3 ′ corresponding to the display position of the reduced screen to the shutter glasses control circuit 15. The shutter glasses control circuit 15 sends a shutter drive signal 104 (41L, 41R) having a shutter opening time t4 'to the shutter glasses 16. The shutter glasses 16 open the shutter at a time t4 'synchronized with the reduced image display time t3'. As a result, the reduced stereoscopic image can be viewed with a good balance between the image brightness and the crosstalk performance.

  FIG. 5 is a diagram illustrating timings of driving signals for the image display unit and shutter glasses for reducing crosstalk. In the first embodiment (FIG. 4), the configuration for improving the image luminance while avoiding the crosstalk has been described. For this purpose, high accuracy is required for the driving signal (shutter opening / closing timing signal) of the shutter glasses. In this embodiment, a method for reducing crosstalk when the shutter opening / closing timing is shifted will be described. FIG. 5 shows the drive signal of the image display unit before and after the correction.

  Assume that the shutter opening time t4 'is shifted by Δt with respect to the reduced image display time t3' in the drive signal (before correction) of the image display unit. Here, when the shutter opening timing is advanced, crosstalk occurs because the previous frame image remains in the lower part of the display screen (near the Q position). Conversely, if the shutter closing timing is delayed, the image of the next frame is displayed at the top of the display screen (near the P position), and crosstalk occurs. That is, crosstalk tends to occur at the upper or lower part of the display screen and hardly occurs at the center of the screen.

  Furthermore, the cause of crosstalk may be caused not only by the deviation of the shutter opening / closing timing but also by the difference in the device characteristics of the display device and the shutter glasses and the fluctuation of the environmental conditions when using these devices. That is, characteristics such as the response responsiveness of the liquid crystal of the display device and the shutter glasses, and the response of the transmitter and receiver of the shutter drive signal may vary depending on the device, and the response speed of the liquid crystal may vary depending on the ambient temperature. . Due to such a change in characteristics, crosstalk occurs at the top or bottom of the display screen.

  On the other hand, in the present embodiment, the drive signal of the image display unit is corrected, and the reduced screen is moved and displayed according to the occurrence state of the crosstalk, thereby suppressing the occurrence of the crosstalk. That is, since the display position of the reduced screen can be freely selected, the display position is biased at the upper part of the screen or at the lower part of the screen while avoiding the position where crosstalk is likely to occur.

  In the corrected drive signal shown in FIG. 5, the screen scanning position is shifted in the direction to advance, and the start point is changed from P to P 'and the end point is changed from Q to Q'. As a result, the shift Δt in timing between the reduced image display time t3 'and the shutter opening time t4' can be eliminated, and the occurrence of crosstalk can be suppressed. Alternatively, when the shutter opening time t4 ′ is longer than the display time t3 ′, the crosstalk is not completely removed, but the crosstalk that is visually recognized is reduced by equally distributing the crosstalk to the upper and lower portions of the screen. effective.

  The operation of this embodiment is realized by the following flow. The viewer operates the remote controller 17 to move the display position of the reduced image in the vertical and horizontal directions (send the display position setting signal 106), thereby adjusting the crosstalk of the stereoscopic image to be viewed (or the apparatus itself). It is also possible to move the display position automatically by measuring the change in the reaction speed of the liquid crystal and estimating the amount of crosstalk). The image display circuit 13 moves the display position of the reduced image according to the display position setting signal 106. However, the image synchronization signal 103 indicating the display time t3 'sent from the image display circuit 13 to the shutter glasses control circuit 15 is not changed. If a new timing relationship between the corrected display position (scanning position) and display time t3 ′ is stored, there is no shutter opening / closing timing shift Δt in subsequent stereoscopic image viewing, and crosstalk adjustment work is reduced. Or become unnecessary.

  In the second embodiment, the display position of the reduced image is moved in order to reduce crosstalk. However, as another method, a structure in which the shutter opening / closing timing is shifted while the display position remains unchanged is also possible. In that case, the viewer may operate the remote controller 17 to send the shutter timing correction signal 107 to the shutter glasses control circuit 15 and adjust so as to reduce the crosstalk of the stereoscopic image to be viewed.

11: Image processing circuit,
12: Image reduction circuit,
13: Image display circuit,
14 ... display part,
15 ... Shutter glasses control circuit,
16 ... Shutter glasses,
17 ... Remote control,
21 ... Reduced display screen,
103: Image synchronization signal,
104: shutter drive signal,
105: Screen reduction ratio setting signal,
106: Display position setting signal,
107: shutter timing correction signal,
t0: time allocated to the frame,
t1, t1 '... In-screen writing time,
t2: Cell response time,
t3, t3 '... display time,
t4, t4 '... Shutter opening time.

Claims (5)

In a stereoscopic image display device that displays a reduced stereoscopic image on a display unit and views the displayed stereoscopic image with shutter glasses,
An image reduction circuit for reducing the stereoscopic image at a predetermined reduction rate;
An image display circuit for displaying the reduced stereoscopic image on the display unit;
A shutter glasses control circuit for supplying an opening / closing timing signal to the shutter glasses;
The image display circuit limits the scanning time in the display unit to the reduced stereoscopic image display area,
The three-dimensional image display device, wherein the shutter glasses control circuit increases the opening time of the shutter glasses by a reduction in scanning time in the display unit. The stereoscopic image display device according to claim 1,
The stereoscopic image display apparatus, wherein the image reduction circuit reduces the stereoscopic image at an instructed reduction ratio in response to an operation instruction from a remote controller. The stereoscopic image display device according to claim 1,
The stereoscopic image display apparatus, wherein the image reduction circuit reduces the stereoscopic image at a reduction rate that provides a predetermined amount of parallax according to the amount of parallax of the stereoscopic image to be displayed. The stereoscopic image display device according to claim 1,
3. The stereoscopic image display apparatus according to claim 1, wherein the image display circuit moves the display position of the reduced stereoscopic image and displays the reduced stereoscopic image in response to an operation instruction from a remote controller. The stereoscopic image display device according to claim 1,
The three-dimensional image display device, wherein the image display circuit moves the display position of the reduced three-dimensional image on the display unit according to a crosstalk occurrence state of the three-dimensional image to be displayed.

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