JPS6346093A - Stereoscopic television receiver - Google Patents

Abstract

PURPOSE:To realize a stereoscopic vision free from flickering without using an optical shutter by using a liquid crystal display device having signal storing function and utilizing the signal storing function and information controllability of picture element device. CONSTITUTION:In a liquid crystal display 46, polarizing plates L (L11, L12,-, L13...) and R (R11, R12,-, 31...) intersecting orthogonally to each other are arranged at every picture element. A scanning driving circuit 44 drives R picture element string successively in case of video signals for a right eye, and drives L picture element string successively, in case of video signals for a left eye. As the two driving circuit 44, 48 are not provided with a refreshing function that refreshes picture elements of liquid crystal display at every field, the liquid crystal display 46 is accessed again at every picture element, and continues to display previous information until new information is written. Thus, no flickering occurs in the picture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stereoscopic television device, and more specifically to a polarization type stereoscopic television device using a liquid crystal display device having a signal storage function.

[Conventional technology]

Stereoscopic television devices have the advantage of allowing captured images to be viewed three-dimensionally, and although the principle has been known for a long time, in recent years it has been put into practical use as a moving image. In order to achieve stereoscopic vision with a television device, as shown in Figure 7, the TV device alternately displays right-eye images and left-eye images, and the viewer views the alternate images with his or her right and left eyes. Take turns observing.

In FIG. 7, 201 and 202 are cameras that form video signals for the right eye and left eye, respectively, and a mixer 203 is
The right eye signal and left eye signal are alternately switched for each field and sent to the TV receiver 204. For example, the mixer 203 uses odd fields as images for the right eye and uses even fields as images for the left eye. Therefore, the image from the right camera 201 appears on the TV receiver 204 in odd-numbered fields, and the image from the left camera 202 in even-numbered fields. The shutter drive circuit 205 receives the vertical synchronization signal of this mixed video signal from the TV receiver 204 and controls opening and closing of the shutters 206 and 207. Shutters 206 and 207 are PLZT
, liquid crystal, or other material that can electrically block light transmission at high speed. For example, the drive circuit 205
4, when the right eye image appears, the right eye shutter 206 is opened, the left eye shutter 207 is closed, and the TV receiver 204 is opened.
When the left eye image appears, close the right eye shutter 206,
Then, the left-eye shutter 207 is opened (. In this way, the viewer will observe the right-eye image and the left-eye image substantially simultaneously due to the afterimage effect, and stereoscopic vision is realized.

Another method for achieving stereoscopic vision is to use polarized light. In this method, two sets of polarizers and analyzers are used to observe a right-eye image and a left-eye image with the right and left eyes, respectively.

On the other hand, liquid crystal display elements have come to be used as display devices for video signals because of their features such as small size, flat panel size, and low power consumption. As a liquid crystal display element for this purpose, a matrix type display as shown in Fig. 5 is adopted because it is a two-dimensional display, and its typical driving method is as follows.
These are the simple matrix addressing method and the active matrix addressing method.

As shown in Figure 5, a matrix type display has a plurality of X-axis electrodes (scanning electrodes) and Y-axis electrodes (display electrodes) orthogonal to each other on each of two substrates sandwiching a liquid crystal. An image is displayed by applying an image signal voltage to the Y-axis electrode while sequentially applying a scanning voltage. A simple matrix addressing scheme simply addresses the X and Y axes, e.g.
By applying voltages to the two axes and the Y2 axis, the pixels (Xz, Y2
). However, in this method, the voltage of 172 of the selected pixel is applied to the pixels (half-selected pixels) in the shaded area other than the intersection (X2, Y2) in FIG. 5, which causes cross talk and deteriorates the display characteristics. make worse.

On the other hand, the active matrix addressing method
As shown in the figure, for each pixel, active elements such as transistors and FETs, switching elements, and capacitors are connected, and the target pixel is driven ``m times'' with the accumulated charge of the capacitor, thereby increasing the contrast.

Among these display liquid crystal elements, devices with a large number of pixels and high definition have been developed that can achieve large screens and high resolution. For example, a ferroelectric liquid crystal with a chiral smectic phase has a high-speed optical switching response, a memory function, that is, a function that maintains the previous display content unless the next signal is written or a reset process is performed, and a time division number. It has the feature that there is no deterioration in image quality even when the image size becomes large, and it is now being used in color LCD TVs. Details of this liquid crystal can be found in U.S. Patent No. 4367924.
No., JP-A-59-193427.

[Problem that the invention seeks to solve]

=5- In the stereoscopic television device using an optical shutter shown in FIG. 7, the right eye image and the left eye image are observed alternately every field or every frame, so the screen flickers and flickers occur. However, it is not very easy to see (also, because it has a complicated structure in which the optical shutter of the glasses part opens and closes in synchronization with the video signal, it lacks ease of use as a stereoscopic image reproduction system.

Therefore, the present invention eliminates flickering caused by flicker, and
Stereoscopic television that does not require an optical shutter in glasses A stereoscopic television device according to the present invention includes an analyzing member for polarization orthogonal to each other in the right eye and left eye of stereoscopic glasses, and a left eye image is transmitted to the left eye through the analyzing member. A stereoscopic television device that realizes stereoscopic vision by observing right-eye images with the right eye, which uses a liquid crystal display device having a signal storage function as a display device, and has right-eye pixels that alternate pixels of the liquid crystal display device. and a pixel column for the left eye, and the pixel column for the right eye is provided with a polarizing member for polarization corresponding to the right eye analyzing member of the glasses.
The left-eye pixel group is provided with a polarizing member for polarization corresponding to the left-eye analyzing member of the glasses, and a right-eye video signal is supplied to the right-eye pixel row, and a left-eye video signal is supplied to the left-eye pixel row.

[Effect]

In the present invention, a liquid crystal display device having a signal storage function is used as a display device, and its signal storage function and information controllability on a pixel basis are utilized. That is, on the playback screen, the pixel row for the right eye and the pixel row for the left eye are arranged in an interlaced manner,
A right-eye video signal is applied to the right-eye pixel column, and a left-eye video signal is applied to the left-eye pixel column. Polarizing plates orthogonal to each other are arranged in front of the right-eye pixel row and the left-eye pixel row, and corresponding analyzers are fitted into the right and left eyes of the viewing glasses. This eliminates the need for optical shutters in the glasses. Further, due to the signal storage function of the liquid crystal display device, both pixel columns maintain the previous display until the display contents are updated, and in winter, there is no display period and flicker is reduced.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1A is a block diagram of an embodiment of a stereoscopic television apparatus according to the present invention. In FIG. 1A, the same members as those shown in FIG. 7 are given the same reference numerals. In FIG. 1A, a changeover switch 10 switches between the stereoscopic video signal from the mixer 203 in FIG. Supplied to circuit 20. The mixer 203 is a circuit that alternately outputs the right-eye video signal from the camera 201 and the left-eye video signal from the camera 202 to the switch 12 for each field.

A video signal detection circuit 22 separates a video signal and an audio signal from the output of the intermediate frequency amplification and AGC circuit 20, and the audio signal of the output signal of the circuit 22 is converted into audio by an audio circuit 24 and a speaker 26.

The video signal output from the video signal detection circuit 22 is amplified by the video signal amplifier 28, converted to a digital signal by the A/D converter 30, and sequentially stored in the line memory 32 for each scanning line. . Further, the synchronization separation circuit 34 separates a horizontal synchronization signal and a vertical synchronization signal from the output of the video signal detection circuit 22, and supplies them to a horizontal oscillation circuit 36 and a vertical oscillation circuit 38, respectively. The timing circuit 40 is a clock that controls A/D conversion in the A/D converter 30, writing/reading to and from the line memory 32, and the shift register 42, respectively, according to the outputs of both oscillation circuits 36 and 38. Forms and outputs signals 40a, 40b, and 40c.

Shift register 42 applies timing pulses to scan drive circuit 44 such that scan drive circuit 44 sequentially drives the scan electrodes of liquid crystal display 46 . Furthermore, the video information data read out from the line memory 32 is
The modulation drive circuit 48 converts the signal into a signal suitable for driving the liquid crystal display 46, and drives the liquid crystal of the corresponding pixel.

The liquid crystal display 46 is a memory that retains the previous signal until the next signal input or signal clear processing is performed.
It is a matrix type display having a (signal storage) function, and is preferably made of a chiral-smectisok phase liquid crystal, which will be described later. This liquid crystal display 46 has a first
As shown in Figure B, polarizing plates L (L++
, L+z, -1L l 3. -) and the same R(R+ 8.
R+t, . The scan drive circuit 44 sequentially drives the R pixel columns in FIG. 1B in the case of the right-eye video signal, and sequentially drives the L pixel columns in FIG. 1B in the case of the left-eye video signal.

Since the redrive circuits 44 and 48 do not have a refresh function that refreshes the pixels of the liquid crystal display for each field, the liquid crystal display 46 displays the previous information until each pixel is accessed again and new information is written. Continue to do so.

Therefore, in this embodiment, the information is different between the odd field and the even field (for example, the left eye video signal in the odd field, the right eye video signal in the even field), and the pixels accessed are also different, so each pixel is stored in one frame. It will be rewritten once. However, due to the memory function of the liquid crystal display 46, all pixels are always displayed except when rewriting, so image information is always input to both eyes, and the screen does not flicker.

FIG. 1C shows the relationship between the polarizer and the analyzer of the glasses for the right eye and the left eye. In addition, it is difficult to differentiate the polarization angle for each pixel between high voltage and low voltage in the case of the same liquid crystal.
In this embodiment, control is performed by inverting the polarity of the drive voltage.

Next, a ferroelectric liquid crystal element having a chiral smectic phase (C3 phase) will be explained.

In addition to its memory function, CS-type liquid crystals with ferroelectric properties are capable of high-speed optical switching, and can display images without degrading image quality even when the number of time divisions becomes large. Therefore, it is suitable for liquid crystal color televisions that aim for flicker-free, multi-pixel, high-definition display.

Normal TN type liquid crystals do not have steep threshold characteristics, so it is difficult to increase the number of scanning lines, and they are not well suited for large screens or high resolution displays.

A CS phase ferroelectric liquid crystal is characterized by having an asymmetric carbon atom in its molecule and having a dipole moment in a direction perpendicular to the long axis of the molecule. This molecular arrangement has a helical structure as shown in FIG. 2, and the direction of spontaneous polarization rotates along the helical axis, so the dipole moment is canceled out as a whole.

However, when the thickness of the liquid crystal cell is made smaller than the helical pitch, the helix unravels and the spontaneous polarization is directed upward (third direction) with respect to the plane of the paper.
Figure 3(a)) or downward (Figure 3(b)). When a DC voltage is applied to the liquid crystal cell in this state, the direction of spontaneous polarization can be aligned in one direction throughout the liquid crystal cell.

The states shown in FIGS. 3(a) and 3(b) are maintained as they are even when the voltage is turned off, and the direction of spontaneous polarization is reversed by applying a voltage of opposite polarity.

Since spontaneous polarization interacts directly with an electric field, switching can be performed in an order of magnitude shorter time than with nematic liquid crystals, which do not have spontaneous polarization. Incidentally, while the switching time of a normal nematic liquid crystal cell is several tens of milliseconds,
With chiral smectic liquid crystals, 0.5 microseconds is also possible, making it possible to operate at high speeds that are approximately four orders of magnitude faster.

A method of driving a matrix type display using such a ferroelectric liquid crystal will be briefly explained.

FIG. 4A (a) is a schematic diagram of a cell 110 having a matrix electrode structure in which a ferroelectric liquid crystal compound is sandwiched. 112 is a scanning electrode group, and 113 is a signal electrode group. FIG. 4A(b) shows the selected scan electrode 112 (S
), (c) shows the electrical signal applied to the unselected scanning electrode 112(n), and (d) shows the electrical signal applied to the selected (information-containing) signal. Electrode 1
13(S), and (e) of the same figure shows an electrical signal applied to an unselected (no information) signal electrode 113(n).

The horizontal axes in (b), (c), (d), and (e) of FIG. 4A represent time, and the vertical axes represent voltage. When displaying a moving image, the scanning electrodes 112 are sequentially and periodically selected.

Let the threshold voltage for giving the first stable state of a liquid crystal cell having bistable property be Vthl, and the dark value for giving the second stable state be 1 and 2, and the voltage value ■ be v〈■5 ,
It is assumed that both <2■ and -V>-V2>=2v are satisfied. The voltage applied to the selection scan electrode 112(s) is the fourth
As shown in Fig. A (b), the alternating voltage is 2■ in the period t1 and -V in the period t2. Non-selected scanning electrode 1
The voltage applied to 12(n) is O (ground) as shown in FIG. 4A (C). On the other hand, selection signal electrode 113 (S
) is applied for a period t as shown in FIG. 4A(d).
, then O1 period 1. Then, it is ■, and the non-selected signal electrode 11
The voltage applied to 3(n) is 0 (ground) as shown in FIG. 4A(e).

When such a voltage is applied to the scanning electrode 112 and the signal electrode 113, the waveform of the voltage applied to each pixel is
Shown in Figure B. FIG. 4B (a).

(b), (c), and (d) are shown in Figure 4A (
This corresponds to pixels A, B, C, and D in a). That is, the fourth
As can be seen from Figure B, all pixels on the selected scanning line are
In the first period t1, the voltage exceeding the dark value voltage −■i2 −2■
is applied, so that the second stable state is first achieved. Then, in the second period t2, the pixel A corresponding to the presence of the information signal shifts to the first stable state because a voltage of 2.times.2.times.2.times.2.times.2.times.2.times.2.times.2.times. However, the pixel B corresponding to no information on the same scanning line remains in the second stable state because the applied voltage in the second period t2 is ■.

On the other hand, pixels on non-selected scanning lines, such as pixels C and D,
The applied voltage is ■ or O, neither of which exceeds the dark value, and the liquid crystal molecules in each pixel C and D retain the orientation of the signal state from the previous scan, in other words, they memorize the signal of the previous screen. There is. Therefore, even if the number of scanning electrodes increases, the actual duty ratio remains unchanged, and no reduction in contrast or crosstalk occurs. The value of the voltage (■) and the signal writing period T (t, +t,) for each pixel depend on the liquid crystal material used and the thickness of the cell, but are usually between 3 volts and 70 volts.
It is in the range of 0.1 μsec to 2 μsec.

When the liquid crystal display of FIG. 4A (a) is used in the embodiment of FIG. 1, the scan drive circuit 44 supplies scan drive signals to the scan electrodes 112 (see FIG. 4A (a)) of the display.

When using a color liquid crystal display, a color filter layer or color polarizing plate is arranged in a mosaic pattern for each pixel, and the transmittance of the three primary colors is controlled individually, but in this way the actual resolution is reduced by 1/2. 3, and the color display ability also deteriorates. Ferroelectric liquid crystals can be driven at high speeds, so
The display screen can be enlarged, and higher-definition images can be displayed than conventional TN liquid crystals.

〔Effect of the invention〕

As can be easily understood from the above explanation, according to the stereoscopic television device of the present invention, stereoscopic viewing can be realized without an optical shutter and therefore without an opening/closing control system, and the signal storage function of the liquid crystal display device enables stereoscopic viewing. , the flickering of the observation screen is
There are none, or even if there are, they are extremely rare.

[Brief explanation of the drawing]

Figure 1A is a block diagram of an embodiment of the device according to the present invention, Figure 1B is a diagram showing the arrangement of polarizers for each pixel on the display surface, and Figure 1C is a diagram showing the arrangement of polarizers for each pixel on the display surface. FIG. 3 is a diagram showing the relationship between the polarizer and the analyzer of the glasses. Figure 2 shows
Figure 3 is a diagram showing the molecular arrangement of a ferroelectric liquid crystal having a chiro-smectic phase, and Figures 4A and 4B are diagrams showing the arrangement of liquid crystal molecules when the thickness of the liquid crystal in Figure 2 is reduced. The figure is an explanatory diagram of the driving method and driving state when driving a ferroelectric liquid crystal in a matrix. Figure 5 is a simplified explanatory diagram of the outer surface of a typical matrix type liquid crystal display. Figure 6 is an active and matrix driving method. FIG. Figure 7 shows
FIG. 1 is a block diagram of the basic configuration of a 3D television device. 12-Selector switch l 4. -VTR device 20
-Intermediate frequency amplification and AGC circuit 22-Video detection circuit
24-Audio circuit 26-Speaker 28-Video amplifier 30-A/D converter 32-Line memory 34--Synchronization separation circuit 36-Horizontal oscillation circuit 3
8... Vertical oscillation circuit 40-timing circuit 42-
Shift register 44-Scanning drive circuit 46-Liquid crystal display 48-Modulation drive circuit 201, 202-Camera 203-Mixer 204-TV receiver 205-
Shutter drive circuit 206.207-Shutter patent applicant Canon Corporation-18=

Claims (2)

[Claims] (1) Stereoscopic vision is achieved by providing an analyzing member for polarized light orthogonal to each other in the right and left eyes of stereoscopic glasses, and observing the left eye image with the left eye and the right eye image with the right eye through the analyzing member. A 3D television device using a liquid crystal display device having a signal storage function as a display device,
The pixels of the liquid crystal display device are divided into alternating right-eye pixel rows and left-eye pixel rows, and the right-eye pixel row is provided with a polarizing member for polarizing light corresponding to the right-eye analyzing member of glasses, and the left-eye pixel row is provided with a polarizing member for polarizing light corresponding to the right-eye analyzing member of glasses. A polarizing member for polarization corresponding to the left eye analyzing member of the glasses is provided,
A stereoscopic television apparatus characterized in that a right-eye video signal is supplied to the right-eye pixel column, and a left-eye video signal is supplied to the left-eye pixel column. (2) Claim No. 1, wherein the liquid crystal display device comprises a ferroelectric liquid crystal having a chiral smectic phase.
3. The stereoscopic television device described in section.