JP2004144988A - Display device and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming back masks by devising write timing without imparting a new circuit to a display device when changing an aspect ratio. <P>SOLUTION: In a display device which is provided with a pixel part where TFTs and liquid crystal cells are arranged in matrix shape, a horizontal scanner means which samples a video signal, a gate control means which controls gates in a row unit and a precharge control means which supplies a precharge signal to data lines, when the first horizontal period signal is turned on from a time a wide control signal indicating that an aspect ratio is different is given, the horizontal scanner means charges black mask data of a video signal on data lines en bloc with respect to pixel parts of areas of upper and lower sides consisting of prescribed rows which form the pixel part and also stops the incoming of a next horizontal period signal and at the same time the gate control means turns TFTs forming pixels on by making the gate lines of the rows of the upper and lower areas consisting of the prescribed rows active for a prescribed period. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a display device and a method of driving the same, and more specifically, does not require a special drive circuit by devising write timing for driving and controlling a liquid crystal element in a display area capable of displaying images with different aspect ratios. The present invention relates to a display device capable of inserting a black mask from a video terminal with low power and a driving method thereof.
[0002]
[Prior art]
A liquid crystal panel image display device, which is a display device according to the related art, displays an image on a liquid crystal panel having an aspect ratio of 3: 4 at an aspect ratio of 3: 4 or at an aspect ratio of 9:16. Are different.
For example, FIG. 5 shows a liquid crystal panel with an aspect ratio of 3: 4 on a liquid crystal panel having an aspect ratio of 3: 4, and the display is displayed in a correct perfect circle because the signals supplied to the display device are compatible. Is done.
FIG. 6 shows a circle on the assumption of an aspect ratio of 9:16 on a liquid crystal panel having an aspect ratio of 3: 4. Since there is no consistency between the display device and the supply signal, the display is not displayed in a correct circle and the ellipse is distorted. Become.
FIG. 7 shows that in order to solve this problem, in the video display device, a black mask is inserted in the upper and lower parts so that the video display area has an aspect ratio of 9:16, and has consistency with the supplied video signal. As a result, the correct circle is displayed.
[0003]
By the timing controller and the gate control circuit, for example, the effective display line corresponds to the PAL signal of 287.5 lines per field in a thinned-out display, so that the liquid crystal panel having 240 vertical lines can be displayed. In order to display a wide image having an aspect ratio of 9:16 on a liquid crystal panel having an aspect ratio of 3: 4, it cannot be realized in a normal image writing time under the following conditions.
When displaying a wide picture of the NTSC system with a panel having 240 vertical lines,
-One field = 16.6 ms
・ Time to scan 240 vertical lines = 63.556 μs × 240 = 15.3 ms
-Total number of upper and lower black mask lines when 9:16 wide display is performed on a panel with 240 vertical lines = 240-(240 x 9/12) = 60-To write 60 wide black masks normally Required time = 60 × 63.556 μs = 3.8 ms
Therefore, the time required for writing a wide display having an aspect ratio of 9:16 by normal scanning is 19.1 ms, which is longer than the time of one field of 16.6 ms.
Although this condition is described using the NTSC system as an example, the same problem occurs in the PAL system.
[0004]
In order to solve such a problem, low-temperature polysilicon performing dot-sequential scanning uses a data line precharge input for improving uniformity and realizes writing of a black mask in 9:16 wide display. ing.
[0005]
In an active matrix type liquid crystal display device, a thin film transistor (TFT) is generally used as a switching element of each pixel. In the active matrix type TFT liquid crystal display device, in the 1H inversion driving method in which the polarity of a video signal applied to each pixel is inverted every 1H (H is a horizontal period) when performing dot sequential driving, each pixel unit is In order to improve the uniformity by suppressing the charge / discharge current due to the writing of the video signal to the data line wired to the data line, a precharge method of writing a precharge signal level before writing the video signal is well known.
As shown in FIG. 8, the configuration of the active matrix TFT liquid crystal display device of the dot-sequential precharge system is such that pixels 113 are arranged in a matrix at intersections of each of a plurality of gate lines 111 and each of a plurality of data lines 112. Are formed, and a precharge control circuit 120 is connected to the data line 112.
[0006]
The pixel 113 includes a TFT (114) having a gate electrode connected to the gate line 111 and a source electrode (or drain electrode) connected to the data line 112, and a drain electrode (or source electrode) of the TFT (114). One of the electrodes is connected to a storage capacitor Cs (115) and a liquid crystal cell Lc (116).
The auxiliary electrode Cs and the other electrode of the liquid crystal cell Lc are connected to a common line (not shown), and a predetermined DC voltage is supplied through the common line.
[0007]
The gate line 111 is connected to the gate control circuit 117, and performs a process of sequentially scanning the gate line 111 every one vertical period (one field period) to select the pixels 113 in units of rows.
[0008]
The data line 112 is connected to a horizontal scanner control circuit 118 and a horizontal scanner 119. When a video signal is input, the data line 112 sequentially samples a video signal of which polarity is inverted every 1H, and scans a row selected by the gate control circuit 117. The writing process is performed for each pixel 113.
In the horizontal scanner 119, the switches connected to the respective data lines 112 are sequentially turned on in accordance with the sequentially output sampling pulses.
[0009]
The precharge control circuit 120 sequentially samples a precharge signal level input with the same polarity as a video signal through a precharge signal line 122 connected to each data line 112 via a precharge switch PSW (121). Then, a process of writing to the pixels 113 in the row selected by the gate control circuit 117 before the video signal is performed.
In this writing, the precharge switch PSW (121) connected between each data line 112 of the pixel 113 and the precharge signal line 122 is turned on collectively by turning on the precharge control signal, and the writing is performed. Will be.
[0010]
As shown in FIG. 9, the configuration of the pixel portion 123, which is a liquid crystal panel using this precharge input, and its control circuit is a liquid crystal panel having a pixel 113, which is a liquid crystal element arranged vertically and horizontally. A video signal processing IC (124) for generating a video signal and a precharge / wide signal for a certain pixel unit 123, a wide control signal indicating that the aspect ratio is 9:16, and a black mask for pixels in upper and lower rows And a timing generator 125 for generating a control signal for performing the control for performing the control.
The video signal processing IC (124) includes means for inputting and outputting a video signal, and a changeover switch 128 for switching between a wide pulse signal generation circuit 126 and a precharge pulse signal generation circuit 127. Output as a signal.
The changeover switch 128 is a switch that is switched by a wide control signal generated by the timing generator 125.
[0011]
In such a configuration, as shown in FIG. 10, writing of a wide black mask is performed prior to writing of a normal video signal in accordance with a vertical synchronization signal.
That is, in the case of the wide black mask writing area, since the wide control signal is turned on, the switch 128 is switched in synchronization with the turning on of the wide control signal to change the precharge / wide signal into the rectangular pulse signal of the wide pulse signal. A wave signal is generated, and this wide pulse signal is supplied to the data line 112 of the pixel 113 (see FIG. 8). At the same time, the wide control signal from the timing generator 125 is held at HIGH, and the precharge control signal is held at LOW.
On the other hand, a control signal is input to the horizontal scanner control circuit 118, and black level data is supplied to the data lines 112 of the pixels 113 in the upper and lower rows of the pixel unit 123 forming a black mask (not shown).
In the case of the normal video writing area, the changeover switch 128 is switched to generate a rectangular wave signal of a precharge signal, and this precharge signal is supplied to the data line 112. At the same time, control is performed to hold the wide control signal LOW, generate a precharge control signal, and supply a precharge pulse signal to the data line 112.
[0012]
As described above, the video signal and the precharge pulse signal are supplied from the video signal processing IC (124) to the liquid crystal panel (pixel unit 123), and when the wide black mask is displayed, the changeover switch 128 is switched to switch the wide pulse. A signal needs to be supplied. This signal requires a larger amplitude than the normal precharge amplitude to write a sufficient black level when writing a wide black mask, and charges this to the data line 112.
[0013]
[Patent Document 1]
JP 2001-51643 A (Page 3-4 Page 1 FIG. 1)
[Patent Document 2]
JP-A-2000-321553 (Page 3-4 Page 4 FIG. 4)
[0014]
[Problems to be solved by the invention]
However, in the low-temperature polysilicon performing the so-called point-sequential scanning described in the above prior art, the data line precharge input signal for improving the uniformity is used, and the black mask for the wide display with the aspect ratio of 9:16 is used. Although writing is realized, the drive focus becomes large in proportion to the increase in the number of horizontal dots, so that a circuit having a large current drive capability is required. As a result, there is a problem in that the drive circuit side has disadvantages such as an increase in cost and an increase in power.
Therefore, there is a problem to be solved by a method of forming a black mask with reduced driving power in a driving circuit that realizes writing of a black mask at the time of wide display with an aspect ratio of 9:16.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, a display device and a driving method thereof according to the present invention have the following configurations.
[0016]
(1) The display device includes a pixel section in which pixels each including a TFT, a liquid crystal cell, and an auxiliary capacitor are arranged in a matrix, horizontal scanner means for sequentially sampling a video signal on a data line of the pixel section, and the pixel section. Gate control means for controlling the gates of the pixels in order for each pixel in a row unit, and precharge control means for supplying a precharge signal for maintaining the uniformity of the data line to the data line. The horizontal scanner means comprises a predetermined row forming the pixel portion when a first horizontal period signal is turned on after a wide control signal indicating that the aspect ratio is different is given. At the same time, black mask data of the video signal is charged into the data lines for the pixel portions in the upper and lower regions at the same time. At the same time as stopping the arrival of the inter-signal, the gate control means activates the gate lines of the upper and lower rows composed of the predetermined row for a predetermined period to turn on the TFT forming the pixel.
(2) When the horizontal control signal is supplied and the first horizontal period signal is turned on, the horizontal scanner means transmits the video signal to the upper and lower pixel units of a predetermined row forming the pixel unit. At the same time, the arrival of the next horizontal period signal is stopped, and at the same time, the gate control means sets the gate lines in the upper and lower regions of the predetermined row to a predetermined period. The display device according to (1), wherein turning on the TFT forming the pixel by making the pixel active is performed a plurality of times.
(3) The display according to (1), wherein the rows in the upper and lower regions activated by the gate control means are divided into a plurality of lines and activated to turn on the TFTs forming the pixels. apparatus.
(4) The display device according to (3), wherein the division of the plurality of lines is divided into even lines and odd lines.
(5) The pixel section generates a display area having an aspect ratio of 3: 4, and the wide control signal is a signal for use in a wide display area having an aspect ratio of 9:16. A display device according to claim 1.
[0017]
(6) The method of driving the display device starts from when a wide control signal indicating that the aspect ratio is different is obtained for a pixel portion in which pixels including TFTs, liquid crystal cells, and auxiliary capacitors are arranged in a matrix. When the horizontal synchronizing signal is turned on, the signal of the black mask image is collectively charged to the data lines of the upper and lower rows of the pixels forming the pixel portion, and the arrival of the next horizontal period signal is stopped. At the same time, the gate lines of the pixels in the upper and lower rows are activated for a predetermined period to turn on the TFT forming the pixels.
(7) When the first horizontal synchronizing signal is turned on from when the wide control signal indicating that the aspect ratios are different is obtained, the signal of the black mask image is transmitted to the upper and lower rows of the pixels forming the pixel portion. Simultaneously charging the data lines and stopping the arrival of the next horizontal period signal, and simultaneously activating the TFTs forming the pixels by activating the gate lines of the pixels in the upper and lower rows for a predetermined period. The method according to (6), wherein the driving is performed twice.
(8) The method of driving a display device according to (7), wherein the data lines of the pixels in the upper and lower rows are divided into a plurality of lines and activated to turn on TFTs forming the pixels. .
(9) The method for driving a display device according to (6), wherein the division of the plurality of lines is divided into even lines and odd lines.
(10) The pixel section generates a display area having an aspect ratio of 3: 4, and the wide control signal is a signal for use in a wide display area having an aspect ratio of 9:16. (6) 4. The method for driving a display device according to claim 1.
[0018]
In this way, by devising the drive timing, a wide black mask can be displayed with the same input as in normal video writing, so that a dedicated drive amplifier can be omitted.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of a display device and a driving method thereof according to the present invention will be described with reference to the drawings.
[0020]
A display device capable of realizing the method of driving the display device of the present invention, that is, a liquid crystal panel image display device, has a wide area image having an aspect ratio of 9:16 in a display region including a pixel portion having an aspect ratio of 3: 4. When displaying the image, the realization of a wide image by applying a black mask on the upper and lower sides is realized by devising the timing without configuring a dedicated circuit for applying the black mask.
As shown in FIG. 1, the configuration includes a horizontal scanner 19 for inputting a black level signal for forming a black mask as a video signal to the data line 12 for sampling, a horizontal scanner control circuit 18 for controlling the same, and a matrix. And a gate control circuit 17 for controlling the gate line 11 thereof, and a precharge control for improving the uniformity of the pixel portion 23 connected to the data line 12. And a precharge control circuit 20 as a means. Among them, the horizontal scanner 19 and the horizontal scanner control circuit 18 constitute horizontal scanner means.
[0021]
The pixel portion 23 includes a TFT (14) having a gate electrode connected to the gate line 11 and a source electrode (or drain electrode) connected to the data line 12, and a drain electrode (or source electrode) of the TFT (14). And a liquid crystal cell Lc (16) to which one electrode is connected.
[0022]
The horizontal scanner control circuit 18 is a circuit that controls a horizontal scanner 19 that inputs a video signal to the data line 12. When a control signal and a wide control signal are input, a data line corresponding to the pixels 13 in the upper and lower rows forming a black mask The control is performed so that the switch of the horizontal scanner 19 that supplies the black level data of the video signal to the switch 12 is turned on.
[0023]
The horizontal scanner 19 performs sampling so that video signal data is input to the data line 12. When the horizontal scanner 19 is wide, that is, when the wide control signal is on, the horizontal scanner 19 is connected to the data line 12 for generating a black mask. Is turned on.
[0024]
The gate control circuit 17 controls the supply of a gate signal to the gate line 11 connected to the gate of the pixel 13. In particular, when the wide control signal is turned on, the gate control circuit 17 synchronizes with the horizontal synchronization signal to connect with the odd gate line. The gate lines are sorted into even-numbered gate lines, odd-numbered gate lines are selected in the first half, and even-numbered lines are selected in the second half, and the gate lines are activated collectively.
Of course, the order of the odd and even gate lines may be reversed.
[0025]
As shown in FIG. 2, the configuration of the liquid crystal panel using the precharge input and the control circuit thereof is different from that of the liquid crystal panel (pixel unit 23) having the pixels 13 arranged vertically and horizontally in an aligned state. A video signal processing IC (24) for generating a signal and a signal for precharge, a wide control signal indicating that the aspect ratio is 9:16, and control for applying a black mask to pixels 13 (see FIG. 1) in upper and lower rows. And a timing generator 25 for generating a control signal.
[0026]
In such a configuration, as shown in FIG. 3, the vertical synchronizing signal is defined as one section, and the video signal is transmitted to the data line 12 through the horizontal scanner 19 (see FIG. 1) prior to normal video writing. And the TFT (14) is kept off during the writing period of the wide black signal, and the TFT (14) is turned on during an appropriate period of the next one horizontal period (1H; usually NTSC 63.556 μS / PAL 64.0 μS). The same charge time is set for all the pixels 13 on which the wide black mask is written. As a result, there is no difference in the charging time between the pixels 13, which is advantageous for uniformity deterioration such as floating black.
When all areas are charged to the same polarity, flicker can be easily recognized, so black writing is divided into even lines and odd lines of the panel, each of which is written with the opposite polarity, and the polarity is inverted for each field. In order to suppress the flicker detection level.
[0027]
Now, at the timing of forming the black mask in synchronization with the horizontal synchronization signal, as shown in FIG. 4, the first horizontal period signal has been turned on since the wide control signal indicating that the aspect ratio is different is given. At this time, when the black mask data of the video signal is collectively charged into the data line 12 for the pixels 13 in the upper and lower regions composed of the predetermined row forming the pixel portion 23, and the arrival of the next horizontal period signal is stopped. At the same time, the gate control circuit 17 activates the gate lines 11 in the upper and lower rows of the predetermined row for a predetermined period to turn on the TFT (14) for forming the pixel 13.
After completion of the wide black mask writing, normal writing is performed and the data line 12 of the pixel 13 is precharged by turning on the precharge control signal.
[0028]
The selection of the gate line 11 is performed by selecting and turning on all of the odd data lines forming the black mask, so that the TFTs (pixels) of the pixels 13 intersecting the data line 12 charged with the charge and the gate line 11 are selected. The gate of 14) is turned on, and the data is simultaneously written to the TFTs (14) of the intersecting pixels 13.
Next, similarly to the selection of the odd data line, when the even data line is selected, the gate of the TFT (14) of the pixel 13 where the data line 12 and the gate line 11 intersect is turned on, and the intersecting pixel 13 is turned on. At the same time.
By performing the above operation a plurality of times, writing is performed a plurality of times so that the same pixel 13 has the same polarity, and it becomes possible to approach the level of the black mask data input from the video signal without limit.
Here, the data line is selected separately for the even data line and the odd data line. However, the present invention is not limited to this, and the data line may be divided into a plurality of predetermined lines for selection.
[0029]
Further, in the wide black mask writing, the horizontal period is not limited to 1H, and may be performed in a period of 1H or more.
[0030]
In this manner, the selection of the data line 12 and the gate line 11 is devised without preparing a special circuit configuration for the pixel 13 forming the black mask, so that the pixel 13 forming the black mask becomes black. Level data can be written.
[0031]
【The invention's effect】
As described above, in the display device and the method for driving the same according to the present invention, by devising the drive timing, it is possible to display the wide black mask with the same input as the normal video writing. A drive amplifier is not required, and as a result, advantages such as cost reduction, downsizing, and low power consumption due to simplification of the circuit can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically showing a circuit configuration of a liquid crystal panel of a display device according to the present invention.
FIG. 2 is a block diagram schematically showing signal processing for driving a liquid crystal panel.
FIG. 3 is a schematic timing chart of wide black writing in a wide writing system in synchronization with vertical synchronization.
FIG. 4 is a schematic timing chart of wide writing of a wide writing method in accordance with horizontal synchronization.
FIG. 5 is an explanatory diagram showing a circle with an aspect ratio of 3: 4 on a liquid crystal panel having an aspect ratio of 3: 4.
FIG. 6 is an explanatory diagram showing a circle with an aspect ratio of 9:16 on a liquid crystal panel having an aspect ratio of 3: 4.
FIG. 7 is an explanatory diagram showing a circle displayed in a display mode with an aspect ratio of 9:16 by applying a black mask on a liquid crystal panel having an aspect ratio of 3: 4.
FIG. 8 is an explanatory diagram illustrating a circuit configuration of a liquid crystal panel according to the related art.
FIG. 9 is a block diagram of a signal processing mode of a liquid crystal panel according to the related art.
FIG. 10 is a schematic timing chart of wide writing in the related art.
[Explanation of symbols]
11; gate line, 12; data line, 13; pixel, 14; TFT, 15; Cs, 16; Lc, 17; gate control circuit, 18; horizontal scanner control circuit, 19; horizontal scanner, 20; , 21; PSW, 23; pixel unit, 24; video signal processing IC, 25;

Claims (10)

A pixel portion in which pixels including a TFT, a liquid crystal cell, and an auxiliary capacitor are arranged in a matrix;
Horizontal scanner means for sequentially sampling the video signal on the data line of the pixel portion,
Gate control means for controlling the gates of the pixels in the pixel unit in order of rows,
Precharge control means for supplying a precharge signal to the data line for maintaining the uniformity of the data line,
A display device comprising:
The horizontal scanner means, when a first horizontal period signal is turned on from a time when a wide control signal indicating that the aspect ratio is different is turned on, the upper and lower regions of a predetermined row forming the pixel portion, At the same time, the black mask data of the video signal is charged to the data line in a lump and the arrival of the next horizontal period signal is stopped, and at the same time, the gate control means controls the gates of the upper and lower rows of the predetermined row. A display device wherein a TFT for forming the pixel is turned on by activating a line for a predetermined period. When the horizontal control signal is supplied and the first horizontal period signal is turned on, the horizontal scanner means applies a black mask of the video signal to the upper and lower regions of the pixel section formed of a predetermined row forming the pixel section. While simultaneously charging data to the data lines and stopping the arrival of the next horizontal period signal, the gate control means activates the gate lines in the upper and lower rows of the predetermined rows for a predetermined period. 2. The display device according to claim 1, wherein turning on the TFT forming the pixel is performed a plurality of times. 2. The display device according to claim 1, wherein the rows in the upper and lower regions to be activated by the gate control means are divided into a plurality of lines and activated to turn on TFTs forming the pixels. 4. The display device according to claim 3, wherein the division of the plurality of lines is divided into even lines and odd lines. 2. The pixel unit according to claim 1, wherein the pixel unit generates a display area having an aspect ratio of 3: 4, and the wide control signal is a signal for use in a wide display area having an aspect ratio of 9:16. Display device. For a pixel portion in which pixels including a TFT, a liquid crystal cell, and an auxiliary capacitor are arranged in a matrix,
When the first horizontal synchronization signal is turned on from when the wide control signal indicating that the aspect ratio is different is obtained, the signal of the black mask image is collectively transferred to the data lines of the upper and lower rows of the pixels forming the pixel portion. And charge,
A driving method for a display device, wherein the arrival of the next horizontal period signal is stopped, and at the same time, the gate lines of the pixels in the upper and lower rows are activated for a predetermined period to turn on a TFT forming the pixel. When the first horizontal synchronizing signal is turned on after obtaining the wide control signal indicating that the aspect ratio is different, the signal of the black mask image is transmitted to the data lines of the upper and lower rows of the pixels forming the pixel portion. A plurality of times of simultaneously charging and stopping the arrival of the next horizontal period signal, and simultaneously activating the TFTs forming the pixels by activating the gate lines of the pixels in the upper and lower rows for a predetermined period. The method for driving a display device according to claim 6, wherein: 8. The method according to claim 7, wherein the data lines of the pixels in the upper and lower rows are divided into a plurality of lines and activated to turn on TFTs forming the pixels. 7. The method of driving a display device according to claim 6, wherein the division of the plurality of lines is divided into even lines and odd lines. 7. The pixel unit according to claim 6, wherein the pixel unit generates a display area having an aspect ratio of 3: 4, and the wide control signal is a signal for use in a wide display area having an aspect ratio of 9:16. A method for driving a display device.

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