JPH11259048A - Plasma address type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma address type liquid crystal display device which does not cause burning on a liquid crystal even if displaying a video signal of a still picture, when displaying a television signal of NTSC system on a liquid crystal by converting it into a sequential scanning video signal. SOLUTION: This plasma address type liquid crystal display device has a sequential scanning signal transformation circuit 12 for transforming a video signal of an interlace scanning method, for example, a television signal of NTSC method into a video signal of a sequential scanning method, a movement adaptive non-correlation processing circuit 19 which performs non-correlation processing of a sequential scanning video signal which does not move at least, an inverting circuit 17 which reverses the non-correlation processed video signal in polarity for every one line and one frame, and a plasma address type liquid crystal display part 18. Since non-correlation processing is executed on a still picture, DC current component is not accumulated in the liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma addressed liquid crystal display device, and more particularly to a plasma addressed liquid crystal display device which processes a video signal of a progressive scanning method with a non-correlated signal component to prevent a liquid crystal portion from burning. Related to the device.

[0002]

2. Description of the Related Art In a plasma addressed liquid crystal display device, display is performed on a liquid crystal unit by writing a voltage in the liquid crystal unit using impedance change at the time of plasma discharge. In a display device using a liquid crystal, when a voltage (DC voltage) in the same direction is applied to the liquid crystal for a long time, a so-called burn-in phenomenon occurs in which the orientation of the liquid crystal is fixed and the liquid crystal does not return to the original state. To prevent this burning,
Inversion drive (AC drive) is performed to periodically invert the polarity of the voltage applied to the liquid crystal and prevent DC voltage from accumulating in the liquid crystal.

When displaying an image such as a television signal on a plasma addressed liquid crystal display device, the period of the inversion drive is two frames for the image signal. In other words, in the plasma addressed liquid crystal display device, the liquid crystal is driven by inverting the video signal every two frames. However, when the entire screen of the liquid crystal display section is driven to be inverted with the same polarity, surface flicker occurs in the plasma addressed liquid crystal display device due to the residual unbalanced component. Is also performed. In this case, the voltage applied to the same pixel of the liquid crystal display switches between positive polarity and negative polarity every frame.

In a plasma addressed liquid crystal display device, a sequentially scanned video signal is displayed. Therefore, video signals of the interlaced (interlaced) scanning method, for example, N
Since a TSC television signal cannot be displayed as it is on a non-interlaced scanning (sequential scanning) plasma addressed liquid crystal display device, the NTSC television signal is converted into a sequential scanning signal, and the converted sequential scanning is performed. Display is performed using video signals.

[0005]

In converting an interlaced scanning video signal such as an NTSC television signal into a progressive scanning video signal (hereinafter referred to as a progressive scanning video signal), the interlaced scanning video signal is used. Since some lines do not exist, it is necessary to complement (interpolate) the video signal. When a new video signal is created by complementing a portion having no video signal by a line in an NTSC television signal, the details will be described later with reference to a specific example. A level difference occurs with the level of the current signal.
The occurrence of the level difference is periodically repeated alternately for each frame. When this cycle matches the cycle of the inversion drive in the display section, the voltage of the level difference between the level of the signal complemented for the still image portion and the level of the current signal is accumulated in the liquid crystal display section, and the liquid crystal burns in. Details of the reason for the occurrence of this burn-in will be specifically described with reference to the drawings.

FIG. 6 is a configuration diagram of a signal processing circuit in a conventional plasma addressed liquid crystal display device. The signal processing circuit in the plasma address type liquid crystal display device has a sequential scanning signal conversion circuit 12 and a signal inversion circuit 17. In the signal processing circuit, an R signal obtained by chroma (color difference) decoding of an NTSC television signal from an input terminal 11 is output.
The RGB signal is inputted, and the RGB signal chroma-decoded in the progressive scanning signal conversion circuit 12 is converted into a progressive scanning video signal (hereinafter referred to as a progressive scanning video signal), and the inversion circuit 17 is turned on.
In step (1), the polarity of the sequentially-scanned video signal is inverted for each line and each frame, and the plasma-inverted liquid crystal display 18 is driven by the inverted signal.

FIG. 7A is a waveform diagram showing an R signal among RGB signals obtained by chroma-decoding the NTSC television signal applied to the progressive scanning signal conversion circuit 12 shown in FIG. B) is a progressive scanning signal conversion circuit 12
FIG. 4 is a waveform diagram in which an R signal is converted into a sequential scanning signal in FIG. In FIGS. 7A and 7B, the R signal of the RGB signals from the (n−2) line to the (n + 2) line and the progressive scanning video signal obtained by converting the R signal into a progressive scanning signal are represented by m fields. The (m + 1) field is shown. In FIG. 7A, the level of the R signal is (n−
2) Line a to line n are level a (a level or voltage of logic 1), and lines (n + 1) to (n)
+2) level 0 (0 level or logic 0)
Voltage). Since the NTSC television signal is interlaced, there are no (n-1) line and (n + 1) line R signals in the m field, and (n-2) line and n line in the (m + 1) field. , (N + 2) lines do not exist.

[0008] As shown in FIG. 7A, in the case of complementing an RGB signal of a television signal of the NTSC system in which a representative R signal does not exist, for example,
In order to complement the video signal of the n lines in the (m + 1) field, the signal of the n lines in the same field, that is, the signal of the n lines in the (m + 1) field is converted into the lines above and below the line, ie, the (n-1) line Averaging the video signal of the (n + 1) line with the video signal of the (n + 1) line, the level of the video signal of the n line in the (m + 1) field becomes a / 2 as follows.

Y (m + 1, n) = (X (m + 1, n-1) + X (m + 1, n + 1)) / 2 = (a + 0) / 2 = a / 2・ (1)

FIGS. 8A to 8C show signals obtained by the above-described signal processing.
5 is a waveform chart showing a voltage applied to a certain liquid crystal in FIG.
FIG. 8A is a waveform diagram showing an n-line sequential scanning signal output from the inverting circuit 17 for m frames to (m + 3) frames, and FIG. 8B is a diagram showing signals of the plasma address type liquid crystal display unit. FIG. 8C is a waveform diagram showing the inversion polarity, and FIG. 8C is a voltage waveform diagram applied to the liquid crystal of the plasma-addressed liquid crystal display unit 18. In this example, the cycle of the inversion drive in the plasma addressed liquid crystal display unit 18 is two frames. Considering the progressive scanning video signal of n lines, the inversion polarity is positive and the signal level is a in the m frame, and the inversion polarity is negative and the signal level is a / 2 in the (m + 1) frame. Since these signal levels continue in a cycle of two frames, the following DC voltage a /
2 stores a DC voltage in the liquid crystal unit. As a result, the liquid crystal is burned.

A− (a / 2) = a / 2

When a signal having a large number of vertical pixels such as a high-definition signal is displayed by a plasma addressed liquid crystal display device in which the number of vertical pixels is less than half, signals of an odd field and an even field are usually superimposed and displayed. In this case as well, in the same manner as the signal obtained by converting the NTSC television signal into a sequential scanning signal for a still image, the inversion driving cycle of the liquid crystal coincides, the level difference between the fields of the video signal accumulates, and Burn.

The problems in the above-mentioned conventional plasma-addressed liquid crystal display device are summarized as follows. 1. Like an NTSC television signal (2:
1) When an interlaced scanning video signal is displayed on a plasma addressed liquid crystal display device, an NTSC television signal is sequentially converted into a scanning video signal for display. In a still image area of the video signal, the same signal is displayed. 1 in display pixel
Since the current signal and the interpolation signal are used alternately for each frame, a level difference occurs between the current signal and the interpolation signal of the same pixel. Since the cycle of this level difference matches the cycle of the polarity inversion of the liquid crystal drive unit, when displaying the same screen for a long time like a still image, a DC voltage due to the level difference is accumulated in the liquid crystal,
The liquid crystal burns. 2. Even when a high-density video signal such as a high-definition video signal is overwritten on a plasma-addressed liquid crystal display device, the cycle of the level difference of the video signal matches the polarity inversion cycle in the liquid crystal display, and the The resulting DC voltage is applied and accumulated, causing the liquid crystal to burn.

An object of the present invention is to overcome the above-mentioned problems, and an object of the present invention is to provide a plasma addressed liquid crystal display device that does not cause liquid crystal burn-in when performing liquid crystal inversion driving in a plasma addressed liquid crystal display device. It is to provide a device.

[0015]

According to a first aspect of the present invention, there is provided a video signal conversion means for converting an interlaced scanning video signal into a progressive scanning video signal, and at least a motionless video signal. Decorrelation processing means for processing the video signal converted to the progressive scanning video signal into a decorrelation component signal, and inversion means for reversing the polarity of the processing signal of the decorrelation component processing means for each line and each frame And a plasma addressed liquid crystal display device having a liquid crystal display unit and plasma addressed liquid crystal display means for driving the liquid crystal display unit in response to the polarity-inverted signal. As described above, by performing decorrelation processing,
In the case of the above-described still image, when the video signal is complemented, the current signal and the complement signal are alternately used for each frame in the same display pixel, so that a level difference occurs between the current signal and the complement signal of the same pixel. To prevent. As a result, no DC voltage is accumulated in the liquid crystal driving section.

Preferably, as a first mode, the decorrelation processing means is a time delay for time-delaying the progressive scan video signal converted by the video signal conversion means by a time having a predetermined relationship with a liquid crystal inversion driving cycle. Means, average value calculating means for calculating an average value of the progressive scanning video signal at the current time and the progressive scanning video signal delayed by the delay means, and video motion of the progressive scanning video signal A motion detecting means for detecting an amount of the image, and the progressive scanning video signal when there is motion in the video, and the average value calculating means when there is no motion, according to the motion amount detection of the video detected by the motion detecting means. Signal selection output means for outputting the operation result. Detects the movement of the video signal and inverts the polarity using the decorrelation processing signal only for a still image without motion, and in the case of a moving image, sequentially inverts the polarity of the video signal to drive the plasma addressed liquid crystal display means I do.

Preferably, the delay time in the time delay means is half of the liquid crystal inversion driving cycle.

Preferably, said time delay means has a first storage circuit for storing said progressively scanned video signal, and said motion detecting means is for storing a sequentially scanned video signal of a previous frame. Means for detecting a motion from a difference between a sequential scanning video signal of a previous frame and a sequential scanning video signal of a current frame. More preferably, the first storage circuit and the second storage circuit are used in common.

Preferably, the motion detecting means detects a motion of a progressively scanned video signal in a frame for each predetermined block. As a result, the processing associated with the motion detection can be performed as finely as a block.

Preferably, the interlaced video signal is an NTSC television signal.

As a second form of the decorrelation processing means, there is provided a time delay means for time-delaying the progressive scan video signal converted by the video signal conversion means by a time having a predetermined relationship with a liquid crystal inversion drive cycle. And average value calculating means for calculating an average value of the progressive scanning video signal at the current time and the progressive scanning video signal delayed by the delay means. In this embodiment, the processing accompanying the motion detection is not performed, but the burn-in of the liquid crystal can be prevented by the decorrelation processing. Further, the circuit configuration is simplified as compared with the decorrelation processing means of the first embodiment. However, the image quality is somewhat reduced.

Preferably, the delay time in the time delay means is half of the liquid crystal inversion driving cycle.

According to a second aspect of the present invention, a first input terminal for inputting an interlaced scanning video signal,
A second input terminal for inputting a progressive scanning video signal, video signal converting means for converting an interlaced scanning video signal input to the first input terminal into a progressive scanning video signal, and signal switching control means And an output signal from the video signal conversion means and a signal input to the second input terminal are received and selected and output according to a first switching control signal from the signal switching control means. First signal selection means, and decorrelation processing means for processing at least a motionless video signal among the signals selected by the first signal selection means into a decorrelation component signal;
A second signal which receives an output signal from the first signal selection means and an output signal from the decorrelation processing means and selects and outputs one according to a second switching control signal from the signal switching control means; Selecting means, inverting means for inverting the polarity of the output signal from the second signal selecting means on a line-by-line and frame-by-frame basis, and a liquid crystal display unit; And a plasma-addressed liquid crystal display device for driving the liquid crystal display.

In the present invention, not only the video signal of the interlaced scanning system is converted into a progressively scanned video signal, but also the signal of the progressively scanned video signal can be inverted and displayed on the plasma addressed liquid crystal display means. Further, in this plasma addressed liquid crystal display device, the sequential scanning signal conversion means can be accommodated in the plasma addressed liquid crystal display device or can be provided outside the plasma addressed liquid crystal display device.

Specifically, the first input terminal has NT
An SC television signal is applied, and a high-definition video signal or a graphic signal is applied to the second input terminal. In the plasma addressed liquid crystal display device, a signal processing for performing a predetermined signal processing on a signal output from the first signal selecting means between the first signal selecting means and the second signal selecting means. Means are provided, and further, signal identification means for identifying any of a high-definition video signal and a graphic signal with respect to the signal output from the first signal selection means is further provided. The signal switching control means applies a first switching control signal for selecting a signal applied to the second input terminal to the first signal switching control means, and applies the signal to the second signal switching control means. When applying a second switching control signal for selecting a signal from the processing means, the second signal selection means:
A signal obtained by subjecting a high-definition video signal or a graphic signal to signal processing is selectively output based on the identification result of the signal identification means. In this way, it is not necessary to process a signal in which the video signal of the same pixel matches between the frames of the still image portion, such as a progressively scanned video signal by a computer signal or digital broadcasting, etc. The type of the video signal is determined based on the frequency of the signal. The above processing is performed on a high-vision signal or a signal obtained by double-converting an NTSC television signal, and the signal is switched to a current time signal for a computer signal, a progressive signal, or the like.

Specifically, the graphic signal is V
This is a GA signal.

As the decorrelation processing means, the first and second embodiments of the decorrelation processing means in the plasma addressed liquid crystal display device according to the first aspect can be applied.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the accompanying drawings.

First Invention First, a plasma addressed liquid crystal display device according to an embodiment of the first invention will be described.

First Embodiment FIG. 1 is a diagram showing a part of a configuration of a plasma addressed liquid crystal display device according to a first embodiment of the present invention. First
The plasma addressed liquid crystal display device according to the first embodiment of the invention includes a progressive scan conversion circuit 12, a motion adaptive decorrelation processing circuit 19, an inversion circuit 17, and a plasma addressed liquid crystal display unit 18. Compared with the plasma-addressed liquid crystal display device illustrated in FIG. 6, the plasma-addressed liquid crystal display device illustrated in FIG. It is added to the circuit 17. The motion adaptive decorrelation processing circuit 19 as decorrelation processing means is configured by connecting a video signal delay circuit 13, an average value calculation circuit 14, a video motion detection circuit 15, and a video signal synthesis circuit 16 as shown in the figure.

FIG. 2A shows the signal processing circuit 1 shown in FIG.
2 is a waveform diagram representatively showing an R signal among the RGB signals obtained by chroma-decoding the NTSC television signal applied to the TV signal 2. FIG. 2B shows the signal processing circuit 12 converting the R signal into a sequential scanning signal. FIG.
(C) is a waveform diagram of a video signal that has undergone decorrelation component processing. In FIGS. 2A, 2B and 2C, (n-2)
The R signal from the line to the (n + 2) line and the signal obtained by sequentially converting the R signal into a scanning signal are represented by m fields and (m + 2).
1) Fields are shown.

An input terminal 11 receives an interlaced scanning video signal, for example, an RGB signal obtained by chroma-decoding an NTSC television signal. The progressive scan conversion circuit 12 uses the NTS applied to the input terminal 11.
The RGB signals obtained by chroma (color difference) decoding of the C-system television signal (FIG. 2A shows the waveform of the R signal of the RGB signals) are sequentially converted into scanning signals (FIG. 2).
(B) shows a waveform obtained by converting the R signal into a sequential scanning signal. In FIG. 2A, the level of the R signal is (n−
2) Line a to line n are level a (a level or voltage of logic 1), and lines (n + 1) to (n +
2) Up to the line is level 0 (0 level or logic 0 voltage). Since the NTSC television signal is interlaced, (n)
There is no R signal for the -1) line and the (n + 1) line,
In the (m + 1) field, there are no R signals for the (n-2) line, the n line, and the (n + 2) line. FIG.
(B) shows a video signal converted into a progressively scanned video signal, and the signal level of the n line of the m frame is a;
The signal level of the (m + 1) frame is a / 2, as described above in the description of the related art.

The signal processing in the motion adaptive decorrelation processing circuit 19 as a first form of the decorrelation processing means will be described. The video signal delay circuit 13 converts the video signal, which has been converted into a progressive scan signal by the progressive scan conversion circuit 12, into a half cycle (for one frame) of a liquid crystal inversion drive cycle (for two frames).
Just delay. As a specific example of the delay of the video signal in the video signal delay circuit 13, for example, a memory for one frame of the sequential scan conversion signal is provided in the video signal delay circuit 13,
The progressive scan conversion signal from the progressive scan conversion circuit 12 is input to and stored in the memory, and is output from the memory when a half of the liquid crystal inversion drive cycle has elapsed.

The average value calculation circuit 14 calculates the average of the video signal delayed by 周期 cycle in the video signal delay circuit 13 and the current progressive scan conversion signal from the progressive scan conversion circuit 12. Since the progressive scanning video signal output from the video signal delay circuit 13 is delayed by a half of the liquid crystal inversion driving cycle, the average of the progressive scanning video signal output from the progressive scanning signal conversion circuit 12 indicates a correlation. , Ie, a video signal of a non-correlation component.

It should be noted that the delay time in the video signal delay circuit 13 is not limited to a half cycle (one frame) of the liquid crystal inversion drive cycle (two frames), but can be set to any time.
However, when the averaging is performed as described above in the average value calculation circuit 14, the time is such that there is no correlation as a result.

Since there is no correlation between the output video signals from the average value calculation circuit 14, even for a still image, the problem of liquid crystal burning caused by the above-described level difference does not occur. Therefore, basically, the video signal of the non-correlation component from the average value calculation circuit 14 can be applied to the inversion circuit 17.
However, in the present embodiment, as a preferred embodiment, using the video motion detecting circuit 15 and the video signal synthesizing circuit 16, a video with motion and a video in a still state are distinguished, and a video without motion, That is, a video signal of a non-correlation component is applied to the inversion circuit 17 only for a still image.

Therefore, the video motion detection circuit 15 detects the video motion of the progressive scan conversion signal output from the progressive scan signal conversion circuit 12. As a method of detecting the motion of the video in the video motion detection circuit 15, for example, the progressive scan conversion signal of the previous frame and the progressive scan conversion signal of the current frame are preferably used for each block,
With 6 × 16 pixels as one block, a difference for each block is calculated, and when the difference exceeds a predetermined value, it is determined that there is motion in the video of the block. Next, the video signal synthesizing (selecting) circuit 16 converts the currently converted progressive scanning video signal from the progressive scanning signal conversion circuit 12 and the progressive scanning video signal of the uncorrelated component output from the average value calculating circuit 14,
A motion detection signal for each block detected by the video motion detection circuit 15 is input, and the motion detection signal for each block from the video motion detection circuit 15 is referred to to detect a motion that may cause a problem in liquid crystal printing. In a still image area (block) having no image, the progressive scanning video signal of the uncorrelated component from the average value calculating circuit 14 is output to the inverting circuit 17. Is output to the inverting circuit 17.

Hereinafter, as a specific example, a decorrelation process in the case where a signal to be displayed on a plasma addressed liquid crystal display device converts an NTSC television signal into a sequential scanning signal will be described. FIG. 2C shows the video signal after the decorrelation component processing, and the signal of the n line of the (m + 1) frame is the average of the signal of the n line of the m frame and the signal of the n line of the (m + 1) frame. Value. FIG. 2 (C)
As illustrated in FIG. 7, the progressive scanning video signal of (m + 1) frame and n lines has the following level because the motion adaptive decorrelation processing circuit 19 has performed the decorrelation component processing.

Z (m + 1, n) = (Y (m, n) + Y (m + 1, n)) / 2 = (a + a / 2) / 2 = (a * 3) / 4・ (2)

That is, the signal level of the n line of the m frame is the average value of the signal of the n line of the (m-1) frame and the signal of the n line of the m frame. This is repeated, and since the video signal of the (m-1) frame is at the same level as the video signal of the (m + 1) frame, it becomes (3a / 4).

The inverting circuit 17 inverts the polarity for each line and each frame from the video signal synthesizing circuit 16 and applies the inverted signal to the plasma address type liquid crystal display section 18 to drive the liquid crystal therein. . In the plasma address type liquid crystal display section 18, a liquid crystal section is displayed by writing a voltage in the liquid crystal section by utilizing an impedance change at the time of plasma discharge.

FIG. 3 is a diagram showing voltage waveforms applied to liquid crystal after decorrelation processing in the plasma addressed liquid crystal display device according to the first embodiment of the first invention. The cycle of the inversion drive of the plasma address type liquid crystal display unit 18 is 2 frames, and when considering the n lines, the inversion polarity is positive and the signal level is (3a / 4) in the m frame, and the inversion polarity of the (m + 1) frame. Is a negative polarity and the signal level is (3a / 4). Since this continues at a cycle of two frames, (3a /
4)-(3a / 4) = 0 and no DC voltage is accumulated in the liquid crystal unit. As described above, by performing the decorrelation process, the current signal and the complementary signal are alternately used for each frame in the same display pixel, which is generated when the video signal is complemented in the case of the above-described still image. This prevents a level difference between the current signal and the complementary signal. As a result, no DC voltage is accumulated in the liquid crystal driving section. Therefore,
According to the present embodiment, the liquid crystal in the plasma addressed liquid crystal display unit 18 does not burn.

[0043] The first invention will be described with a plasma addressed liquid crystal display device of the second embodiment of the second invention according to the second embodiment with reference to FIG. FIG. 4 shows the second aspect of the second invention.
1 is a configuration diagram of a plasma addressed liquid crystal display device as an embodiment of the present invention. The plasma addressed liquid crystal display device illustrated in FIG. 4 is obtained by deleting the video motion detection circuit 15 and the video signal combining circuit 16 from the motion adaptive decorrelation processing circuit 19 in the plasma addressed liquid crystal display device illustrated in FIG. A decorrelation processing circuit 21 having a simple configuration including a video signal delay circuit 13 and an average value calculation circuit 14;
It has a progressive scanning signal conversion circuit 12, an inversion circuit 17, and a plasma address type liquid crystal display section 18. That is, FIG.
The plasma addressed liquid crystal display device illustrated in FIG. 1 does not perform processing according to the motion of a video signal in which the motion of a sequentially scanned video signal is detected as in the plasma addressed liquid crystal display device illustrated in FIG.

In the plasma addressed liquid crystal display device of the second embodiment, an RGB signal obtained by chroma-decoding an NTSC television signal applied to the sequential scanning signal conversion circuit 12 illustrated in FIG. FIG.
R in the progressive scanning signal conversion circuit 12 illustrated in FIG.
A signal obtained by converting a GB signal into a progressively scanned video signal can be applied, and a video signal which has been subjected to decorrelation component processing as illustrated in FIG.

The input terminal 11 receives an interlaced scanning video signal, for example, an RGB signal obtained by chroma-decoding an NTSC television signal. The progressive scan conversion circuit 12 uses the NTS applied to the input terminal 11.
The RGB signals obtained by chroma (color difference) decoding of the C-system television signal (FIG. 2A shows the waveform of the R signal of the RGB signals) are sequentially converted into scanning signals (FIG. 2).
(B) shows a waveform obtained by converting the R signal into a sequential scanning signal.

Decorrelation processing circuit 2 as decorrelation processing means
1 will be described. The video signal delay circuit 13 delays the video signal converted into the sequential scanning signal by the sequential scanning conversion circuit 12 by 周期 cycle (one frame) of the liquid crystal inversion driving cycle. Video signal delay circuit 13
As a specific example of the delay of the video signal in
For example, the progressive scan conversion signal 1 is supplied to the video signal delay circuit 13.
A memory for a frame is provided, and a progressive scan conversion signal from the progressive scan conversion circuit 12 is input to the memory and stored therein.
Output from the memory when the time of one frame has elapsed. The average value calculation circuit 14 calculates the average of the video signal delayed by a half cycle (only one frame) in the video signal delay circuit 13 and the current progressive scan conversion signal from the progressive scan conversion circuit 12. Since the progressive scan video signal output from the video signal delay circuit 13 is delayed by one frame, when the progressive scan video signal output from the progressive scan signal conversion circuit 12 is averaged, the uncorrelated video signal, that is, It becomes a video signal of a correlation component. Note that the delay time in the video signal delay circuit 13 is not limited to one frame as described in the first embodiment.

The video signal of the uncorrelated component from the average value calculating circuit 14 is applied to the inverting circuit 17. In the inverting circuit 17, the average value calculating circuit 14 is provided for each line and each frame.
, The polarity of the sequentially scanned video signal is inverted, and the liquid crystal is driven in the plasma address type liquid crystal display unit 18.

In the second embodiment of the first invention, since the selection processing based on the presence or absence of motion is not performed as in the first embodiment of the first invention, the video signal subjected to the decorrelation processing even in the moving picture signal area is used. Is applied to the inverting circuit 17. As a result, the image quality of the image displayed on the plasma address type liquid crystal display unit 18 may be slightly blurred, but the liquid crystal is not burned. That is, the plasma addressed liquid crystal display device of this embodiment has an advantage that the circuit configuration is simplified although the image quality is reduced.

A plasma addressed liquid crystal display of the second invention
Described plasma addressed liquid crystal display device of the second aspect of the location present invention. In the second plasma addressed liquid crystal display device of the present invention, a progressive scanning video signal such as a computer signal or a digital broadcast, an NTSC television signal, a signal obtained by converting an NTSC television signal at a double speed, a high-definition video signal, etc. Can be displayed even when there is a In the case where video signals of the same pixel coincide between frames of a still image portion, such as a computer signal, a progressive signal, a progressively scanned video signal of digital broadcasting, etc., it is necessary to perform signal processing as in the first invention. There is no. On the other hand, as described above, in the case of an NTSC television signal, a signal obtained by double-speed conversion of an NTSC television signal, or a high-vision signal, conversion to a progressive scanning video signal is necessary as in the first invention. Become. Therefore, the plasma addressed liquid crystal display device of the second invention detects an input video signal, selects whether or not to convert the input video signal into a progressively scanned video signal in accordance with the video signal. When a video signal is converted into a progressively scanned video signal, whether or not it is necessary to perform decorrelation processing is identified and output to an inversion circuit is performed.

That is, in the plasma addressed liquid crystal display device of the second invention, the type of the video signal is determined based on the frequency of the video signal input to the input terminal and the frequency of the synchronization signal of the video signal. In the case of the television signal or the high-definition video signal of the system, the same processing as in the first invention is performed, and the polarity inversion is performed without performing any special processing on the computer signal, the progressive signal, or the like.

Second Embodiment, First Embodiment FIG. 5 is a block diagram of a plasma addressed liquid crystal display device according to a first embodiment of the second invention. This plasma addressed liquid crystal display device has a progressive scanning signal conversion circuit 33 corresponding to the progressive scanning signal conversion circuit 12 of the first invention described above,
It has an inverting circuit 38 corresponding to the inverting circuit 17 described above, and a plasma-addressed liquid crystal display 39 corresponding to the plasma-addressed liquid crystal display 18 described above. The plasma addressed liquid crystal display further includes a switching circuit 3
4, a signal processing circuit 35, a decorrelation processing circuit 36, a switching circuit 37, a switching control circuit 40, and a signal detection circuit 41.
In this plasma address type liquid crystal display device, a progressive scanning signal conversion circuit 33 as a progressive scanning signal converting means.
Can be housed inside the plasma addressed liquid crystal display device, or can be provided outside the plasma addressed liquid crystal display device.

In this example, the first input terminal 31 has a video signal of an interlaced scanning system, for example, N signal.
A TSC television signal is applied, and is converted into a progressively scanned video signal in a progressively scanned signal conversion circuit 33. The progressive scanning signal conversion circuit 33 converts an NTSC television signal into a progressive scanning video signal. The details of the operation of the progressive scanning signal conversion circuit 33 are the same as the operations of the progressive scanning signal conversion circuit 12 described above with reference to FIG.
The progressive scanning video signal converted by the progressive scanning signal conversion circuit 33 is applied to the switching circuit 34.

In this example, a high definition video signal or a VGA signal is applied to the second input terminal 32. In the case of a high-definition signal, since the overwriting display is performed without converting to the sequential operation, the processing in the progressive scanning signal conversion circuit 33 is not necessary. Therefore, the high definition video signal is applied to the second input terminal 32. The second input terminal 32 is connected to, for example, a VGA signal (Video Graphic).
Array signal) can also be applied. VGA is a video adapter released by IBM Corporation, and two graphic modes have been proposed. The first mode supports a screen of 640 horizontal pixels × 480 vertical pixels that can simultaneously select 2 or 16 colors from a 262,144 color table per pixel. The second mode is 260,214 per pixel
Horizontal pixels 320 capable of simultaneously selecting 256 colors from four color tables. Support vertical screen 200 kicking.

In this example, the switching circuit 34 has the first
An input terminal 31 receives an NTSC television signal, and a second input terminal 32 receives a high definition video signal or a VGA signal. The switching control circuit 40 controls switching between the switching circuit 34 and the switching circuit 37,
And the signal from the second input terminal 32 are selectively output.

The signal processing circuit 35 converts the video signal output from the switching circuit 34 into a plasma address type liquid crystal display 39.
As in the case of an ordinary television receiver for displaying a picture, common signal processing such as picture control and multiplex processing of an on-screen display signal is performed.
The processing signal of the signal processing circuit 35 is directly applied to the switching circuit 37.

The decorrelation processing circuit 36 can take the circuit configuration of the motion adaptive decorrelation processing circuit 19 of the first embodiment of the first invention or the decorrelation processing circuit 21 of the second embodiment. When the circuit configuration of the motion adaptive decorrelation processing circuit 19 is adopted, the decorrelation processing is applied only to the still image, and when the circuit configuration of the decorrelation processing circuit 21 is adopted, the decorrelation processing is applied regardless of the still image and the moving image. Will do.

The signal detection circuit 41 will be described. The switching circuit 34 and the switching circuit 37 cannot distinguish between the VGA signal and the high-vision signal. Therefore, the signal detection circuit 41 distinguishes between the VGA signal and the high-vision signal. As the detection method, the horizontal scanning frequency of the VGA signal is 41.5 kHz, and the horizontal scanning frequency of the high-definition signal is different from 33.75 kHz. Selectively output high-definition video signal or V
A determination is made as to a GA signal. The determination signal of the signal detection circuit 41 is input to the switching circuit 37.

The output signal of the signal processing circuit 35 and the output signal of the decorrelation processing circuit 36 are applied to the switching circuit 37. When the switching control circuit 40 selects the signal of the first input terminal 31, When the output of the correlation processing circuit 36 is selected and output, and the switching control circuit 40 selects the signal of the second input terminal 32, the signal is further output from the signal processing circuit 35 with reference to the detection signal of the signal detection circuit 41. And a VGA signal. The signal selected and output from the switching circuit 37 is applied to the inverting circuit 38 to invert the polarity, and is displayed on the plasma address type liquid crystal display unit 39.

As described above, according to the first embodiment of the second invention, various processes are performed while appropriately processing according to the signal to be displayed on the plasma address type liquid crystal display section 39 to prevent the liquid crystal from burning. Signal is applied to the plasma address type liquid crystal display unit
9 can be displayed. The interlaced scanning video signal applied to the first input terminal 31 and the progressive scanning video signal applied to the second input terminal 32 are not limited to the above-described signals.

Second Embodiment and Other Embodiments In the first embodiment of the second invention described with reference to FIG. 5, an NTSC television signal is applied to a first input terminal 31, and It is assumed that a high definition video signal or a VGA signal is applied to the second input terminal 32. Therefore, a signal detection circuit 41 is provided to identify the signal applied to the second input terminal 32, and the switching circuit 3
In 7, the signal selection according to the identification result was performed. However, when only one of the high-definition video signal and the VGA signal is applied to the second input terminal 32,
There is no need to provide the signal detection circuit 41 and the switching circuit 37
Does not need to be performed.

Further, an NTSC television signal is applied to the first input terminal 31 and the second input terminal 32
When only the high-definition video signal is applied, the signal processing circuit 35 may perform only the signal processing for the high-definition video signal.

Alternatively, NTSC is input to the first input terminal 31.
System television signal is applied to the second input terminal 3
In the case where only a VGA signal is applied to 2, the signal processing circuit 35 only needs to perform signal processing for the VGA signal.

[0063]

According to the first aspect of the invention, by performing decorrelation processing of a video signal, it is possible to prevent the occurrence of printing of liquid crystal in a still image or the like.

According to the second aspect of the present invention, furthermore, video signals of the interlaced scanning system, progressively scanned video signals, and other signals can be selectively displayed while preventing the liquid crystal from burning.

[Brief description of the drawings]

FIG. 1 is a diagram showing a part of a configuration of a plasma addressed liquid crystal display device as a first embodiment of the first invention of the present invention.

FIG. 2A is a waveform diagram typically showing an R signal among RGB signals obtained by chroma-decoding an NTSC television signal applied to the signal processing circuit 12 shown in FIG. 1; FIG. 2B is a waveform diagram in which the R signal is sequentially converted into a scanning signal in the signal processing circuit 12, and FIG.
FIG. 4 is a waveform diagram of a video signal on which a non-correlation component process has been performed.

FIG. 3 is a diagram showing voltage waveforms applied to the liquid crystal after the decorrelation component processing in the plasma addressed liquid crystal display device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a part of a configuration of a plasma addressed liquid crystal display device as a second embodiment of the first invention of the present invention.

FIG. 5 illustrates a plasma addressed liquid crystal display device according to a second aspect of the present invention with reference to FIG.

FIG. 6 is a configuration diagram of a signal processing circuit in a conventional plasma addressed liquid crystal display device.

7A is a waveform diagram showing an R signal among RGB signals obtained by chroma-decoding an NTSC television signal applied to the progressive scanning signal conversion circuit shown in FIG. 6, and FIG. B) is a waveform diagram in which the R signal is converted into a sequential scanning signal in the sequential scanning signal conversion circuit.

8 (A) to 8 (C) are waveform diagrams showing signals obtained by signal processing in the plasma addressed liquid crystal display device of FIG. 6 and showing a voltage applied to a certain liquid crystal in the plasma addressed liquid crystal display unit. FIG. 8A is a waveform diagram showing a sequential scanning signal output from the inverting circuit.
FIG. 8B is a waveform diagram showing the inversion polarity of the signal of the plasma address type liquid crystal display unit, and FIG. 8C is a voltage waveform diagram applied to the liquid crystal of the plasma address type liquid crystal display unit.

[Explanation of symbols]

 11, input terminal 12, progressive scan conversion circuit 17, inversion circuit 18, plasma address type liquid crystal display unit 19, motion adaptive decorrelation processing circuit 13, video signal delay circuit 14, average value calculation circuit 15 ..Video motion detecting circuit 16 video signal synthesizing circuit 21 decorrelation processing circuit 31 first input terminal 32 second input terminal 33 progressive scanning signal conversion circuit 34 switching circuit 35 ..Signal processing circuit 36.Decorrelation processing circuit 37.Switching circuit 38.Inverting circuit 39.Plasma address type liquid crystal display

Claims (20)

[Claims] 1. A video signal converting means for converting an interlaced scanning video signal into a progressive scanning video signal, and at least for a motionless video signal, converting the video signal converted into the progressive scanning video signal into a non-moving video signal. A non-correlation processing means for processing the correlation component signal, an inversion means for inverting the polarity of the processing signal of the non-correlation component processing means for each line and each frame, and a liquid crystal display unit. A plasma-addressed liquid crystal display device comprising: a plasma-addressed liquid-crystal display unit for driving the liquid-crystal display unit in response to the request. 2. The non-correlation processing means comprises: a time delay means for delaying the progressive scan video signal converted by the video signal conversion means by a time having a predetermined relationship with a liquid crystal inversion driving cycle; Average value calculating means for calculating an average value of the progressive scanning video signal and the progressive scanning video signal delayed by the delay means; and motion detecting means for detecting a video motion amount of the progressive scanning video signal. A signal selection unit that outputs the progressive scanning video signal when there is a motion in the video and outputs the calculation result of the average value calculation unit when there is no motion, according to the motion amount detection of the video detected by the motion detection unit. 2. The plasma addressed liquid crystal display device according to claim 1, further comprising an output unit. 3. The plasma addressed liquid crystal display device according to claim 2, wherein a delay time in said time delay means is half of said liquid crystal inversion driving cycle. 4. The time delay means has a first storage circuit for storing the progressively scanned video signal, and the motion detecting means is a second storage means for storing a sequentially scanned video signal of a previous frame. 2. The plasma addressed liquid crystal display device according to claim 1, wherein a motion is detected from a difference between a sequentially scanned video signal of a previous frame and a current frame of the current frame. 5. The plasma addressed liquid crystal display device according to claim 4, wherein said first storage circuit and said second storage circuit are used in common. 6. The motion detecting means for detecting a motion of a progressively scanned video signal in a frame for each predetermined block.
The plasma-addressed liquid crystal display device according to claim 1. 7. The plasma addressed liquid crystal display device according to claim 2, wherein the interlaced video signal is an NTSC television signal. 8. The decorrelation processing means: a time delay means for delaying the progressive scan video signal converted by the video signal conversion means by a time having a predetermined relationship with a liquid crystal inversion drive cycle; 2. The plasma addressed liquid crystal display device according to claim 1, further comprising an average value calculating means for calculating an average value of the progressive scanning video signal and the progressive scanning video signal delayed by said delay means. 9. The plasma addressed liquid crystal display device according to claim 5, wherein a delay time in said time delay means is half of said liquid crystal inversion driving cycle. 10. The plasma addressed liquid crystal display device according to claim 8, wherein said interlaced video signal is an NTSC television signal. 11. A first input terminal for inputting an interlaced scanning video signal, a second input terminal for inputting a progressively scanned video signal, and an interlaced scanning video input to the first input terminal. Video signal converting means for converting a signal into a progressive scanning video signal; signal switching control means; receiving the output signal from the video signal converting means and the signal input to the second input terminal; First signal selecting means for selecting and outputting one of the signals in accordance with a first switching control signal from the switching control means, and at least an image having no motion among the signals selected by the first signal selecting means A signal processing unit that processes the video signal into a non-correlation component signal; accepts an output signal from the first signal selection unit and an output signal from the decorrelation processing unit; A second signal selecting means for selecting and outputting one of them according to a second switching control signal from the switching control means; and a polarity of the output signal from the second signal selecting means for each line and each frame. And a plasma-addressed liquid crystal display having a liquid crystal display, and plasma-addressed liquid crystal display for driving the liquid crystal display in accordance with the polarity-inverted signal. 12. An NTSC television signal is applied to the first input terminal, a high-definition video signal or a graphic signal is applied to the second input terminal. , A signal processing unit for performing predetermined signal processing on a signal output from the first signal selection unit is provided between the first signal selection unit and the second signal selection unit. About the signal
A signal identification unit for identifying any one of a high-definition video signal and a graphic signal; and the signal switching control unit selects the signal applied to the second input terminal to the first signal switching control unit. When a second switching control signal for selecting a signal from the signal processing unit is applied to the second signal switching control unit, the second signal selection unit includes: 12. The plasma addressed liquid crystal display device according to claim 11, wherein a signal obtained by subjecting a high-definition video signal or a graphic signal to signal processing is selectively output based on the identification result of the signal identification means. 13. The plasma addressed liquid crystal display device according to claim 12, wherein said graphic signal is a VGA signal. 14. The decorrelation processing means: a time delay means for delaying the progressive scan video signal converted by the video signal conversion means by a time having a predetermined relationship with a liquid crystal inversion drive cycle; Average value calculating means for calculating an average value of the progressive scanning video signal and the progressive scanning video signal delayed by the delay means; and motion detecting means for detecting a video motion amount of the progressive scanning video signal. A signal selection unit that outputs the progressive scanning video signal when there is a motion in the video and outputs the calculation result of the average value calculation unit when there is no motion, according to the motion amount detection of the video detected by the motion detection unit. 13. The plasma addressed liquid crystal display device according to claim 12, further comprising an output unit. 15. The plasma addressed liquid crystal display device according to claim 14, wherein a delay time in said time delay means is half of said liquid crystal inversion driving cycle. 16. The time delay means has a first storage circuit for storing the progressively scanned video signal, and the motion detecting means includes a second storage means for storing a sequentially scanned video signal of a previous frame. 15. The plasma addressed liquid crystal display device according to claim 14, wherein the motion is detected from a difference between a sequential scanning video signal of a previous frame and a current scanning video signal of a current frame. 17. The plasma addressed liquid crystal display device according to claim 16, wherein said first storage circuit and said second storage circuit are used in common. 18. The plasma addressed liquid crystal display device according to claim 16, wherein said motion detecting means detects a motion of a progressively scanned video signal in a frame for each predetermined block. 19. The non-correlation processing means includes: a time delay means for delaying the progressive scan video signal converted by the video signal conversion means by a time having a predetermined relationship with a liquid crystal inversion drive cycle; 13. The plasma addressed liquid crystal display device according to claim 12, further comprising an average value calculating means for calculating an average value of the progressive scanning video signal and the progressive scanning video signal delayed by said delay means. 20. The plasma addressed liquid crystal display device according to claim 19, wherein a delay time in said time delay means is half of said liquid crystal inversion driving cycle.