JPS61232494A - Display method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device, and particularly to a display method using a matrix type display device.

Prior Art Active matrix display devices, in which display units are provided at the intersections of column electrode bus lines and row electrode bus lines, are being actively researched because they can be made flat. FIG. 2 shows a principle diagram of an active matrix type display device. As shown in FIG. 2, a display unit 3 is formed at the intersection of an electrode bus line (X selection line) 1 for transmitting a display signal and an electrode bus line (Y selection line) 2 for transmitting a scanning signal. Horizontal driver 4. Using the vertical dry nozzles 6, the address of a specific display unit 3a at the m a n address (indicating the m row and n column) indicated by diagonal lines in the figure is designated by the m-th electrode bus line and the n-th electrode bus line.

Each display unit is a MOS transistor (
Insulated gate field effect transistor) 11° liquid crystal 12.
A conventional technique will be explained using a display device using a display unit represented by an auxiliary capacitor 130 equivalent circuit. MO from X selection line
S) When a scanning signal that turns on the transistor 11 is input, the display signal transmitted to the Y selection line can be transmitted to the liquid crystal 12. For example, as shown in FIG. 4a, a transistor is connected to the m-th Y selection line for one row (1H period).
N scanning signals are transmitted to the X selection line in sequence in Figures 4b-c.
When a display signal is transmitted as shown in FIG. 1, a display signal for one horizontal row is given. When one horizontal row is completed, a display signal is transmitted to the display unit row on the (m+1)th Y selection line.

However, if the switching element like the MOS transistor 11 in Fig. 3 is formed of something like a slow-response thin film transistor, the display signal will change over a short period of time as shown in Fig. 4 b to d. cannot be transmitted to the liquid crystal element 12. So the 6th
A method is used in which one row's worth of display signals is temporarily stored in a memory at the timing shown in the figure, and one row's worth of display signals are simultaneously transmitted within one row's worth of scanning signals. This is called the line sequential method.

Problems to be Solved by the Invention Although the conventional line sequential method requires more memory for one row than the point sequential method, the number of display units in the active matrix is limited as shown by the broken lines in FIG. Even if the response of the switch was somewhat slow, the display signal could be transmitted to the display element. However, as display devices become larger and have higher resolution, the resistance component of the electrode busbars and the capacitance component due to the unity between the electrode busbars increase, resulting in signal delays and slow start-up times, resulting in uneven display. It has become a problem. For example, 6 inches 480X19
The source bus (Y selection line) of 20 display elements is made of Al with a thickness of 8 μm.
When the gate bus (X selection line) is formed with Cr to a width of 16 μm, the resistance per display rate is o, 1 at the source bus.
7Ω, 310Ω for the gate bus, and the capacitance of the source-gate type portion is 1.2×10”F, which cannot be ignored.

Means for Solving the Problems The present invention provides a first electrode bus group for transmitting display signals, a second electrode bus group for transmitting scanning signals, and a first electrode bus group for transmitting a scanning signal. In a display device comprising a display unit that forms a display unit corresponding to an intersection point and has a switch driven by both of the signals, the time at which transmission of the scanning signal starts to cause the switch to conduct the display signal is the time when the transmission of the scanning signal starts. It is characterized by being earlier than the transmission start time of the display signal group to be transmitted to the display unit group intersecting the second electrode bus line, and how much earlier the transmission of the scanning signal is started than the display signal is determined. The time required for the scanning signal to uniformly propagate to the second electrode busbar may be appropriate, but it should be determined in relation to the quality of the screen.

In either the application point sequential method or the line sequential method, scanning signals are transmitted to the Y selection lines one after another at the timing shown in FIG. However, as mentioned above, with the increase in size and high resolution of display devices, the scanning signal is
As shown by the broken line in the figure, the scanning time for one row (1H) is insufficient to raise the desired voltage, and the display signal is not properly transmitted to the display element.

If the timing of the scanning signal and display signal of the present invention is transmitted as shown in FIG. 1, the slow rise of the scanning signal will no longer be a problem. That is, even if the scanning signal rises to the same level as the broken line in FIG. 6, the display signal is input only after the scanning signal reaches the desired value, so that a correct display signal is provided.

At this timing, the display signal of the (--1)th line becomes m
Row number.

Although it is temporarily transmitted to the display unit on the (-+1)th row, it eventually reaches the original display signal, so if the display due to this temporary false signal is not noticeable to the observer, then No problem. Particularly when a slow response display element such as a liquid crystal is used, almost no deterioration in display quality due to this false signal is observed.

Example - A specific example will be explained below using an example of a liquid crystal display board.

Example 1 A liquid crystal display panel having the overall configuration as shown in FIG. 2 and display units as shown in FIG. 3 was formed on a single crystal Si substrate. 11
The transistor is a MOS transistor, and the auxiliary capacitor 13 is formed using 5i02. A timing chart of the scanning pulses transmitted to this display board is shown in the gy diagram. A unit scan pulse of IH=60 μsec is transmitted for 2H, and the MOS transistor 11 is turned on. The scanning signal is delayed by 1H for each row. The display device was driven in a dot-sequential manner in which display signals to be input to display units of rows were sent one after another during a 1M period (shaded area in FIG. 7) in the latter half of the scanning pulse. When scanning pulses were transmitted at the timing shown in FIG. 7, a sufficient reflective television image could be obtained even with a screen size of 4 inches, 250×320 pixels.

Example 2 FIG. 8 shows the overall configuration of a display device according to a second embodiment of the present invention.

TPT liquid crystal display board 21. Related H driver 22. ■
Each of the drivers 23 is divided by a broken line. The switch element 24 constituting the display unit in FIG. 8 is a plasma CV
By method D, a thin film transistor (TPT) whose main materials are amorphous silicon and silicon nitride is used, and the auxiliary capacitor is formed from silicon nitride. 26F! A liquid crystal is used as a display element. The image signal 27 is sampled by a signal sampling circuit 28 and transferred to n memories 2 corresponding to 1H of picture elements.
Enter 9. Control MO331 by signal sending pulse 3o
ON L, 1 at the same time through n display signal bus lines 32
Send display signal for rows. (2) The scanning signal sent from the driver 23 to the scanning signal bus 33 is shown in FIG. Each scan pulse is transmitted for 165H in units of 1H of 60 μsec, and the TPT 24 is turned on. For each row, the scanning signal is delayed by 1H. A display device employing a line sequential system in which display signals to be sent to display units of rows during periods o and sH in the second half of the scanning pulse (shaded area in FIG. 9) are simultaneously sent by turning on a sending control MOS transistor 31 using a sending pulse 30. A light-transmissive image was obtained on a 03-inch 260 x 320 pixel screen that was driven by .

Embodiment 3 A TPT drive liquid crystal display panel 41 shown in FIG. 10 was constructed of TPT whose main materials are amorphous silicon and silicon nitride by a normal plasma CVD method. However, this display panel is different from Embodiment 2. In addition to the TFT 42 of the display element, an on/off switch TFT 43 is provided at the end of the signal side bus bar, and an on/off switch TFT 44 is also provided at the end of the scanning side bus bar.
0 (TVl...) are created at the same time (However, these switches TPT do not need to be created simultaneously for both bus bars, and may be created for only one bus bar. ) The details of the operation of these switches TPT and the display device using the driving method of the present invention will be described below.

) Image signal transmission: The video input 51 to the H driver on the H driver side is sampled and
The data is stored in n memories 62 corresponding to H picture elements. 1H
Sending timing pulses P, Q divided by N (=3)
, R and the transmission control gate lines Ta, Tb, Tc can be arbitrarily combined by a transmission timing switch 53.

Each of the image signals grouped for each redundancy degree N (==3) is sent out from the output amplifier 54 in time series at every time that 1H is divided by N (=3).

On the other hand, on the array side of the TFT 42, a switch TFτ43 is connected to both ends of each signal bus. These are the input signals P, Q to the reception timing switch 66, and the control line Ga connected to the S signal which is always at level 1.
, Gb, and Ga. In addition, when switching the sending/receiving timing, it is necessary to use Ta-Ga, Tb-G.
b, Tc-Gc are synchronously connected to P, Q, R, and S.

In the above, it has been explained that the gate line Gc is always at 1 level, but if the influence of the direct coupling voltage of the gate pulse due to the capacitance between the gate and drain of the switch TPT can be ignored on the video signal transmitted through the bus line. If not,
The gate line Gc may be set to the 0 level for a very short time just before the V scanning side pulse becomes the 0 level after the last 20 μsec.

bx scanning multiplication signal transmission: V driver side As shown in FIG. 11, the gate signal of the picture element TFT 42, that is, the scanning pulse has a width of 3H, and overlaps with the adjacent upper and lower signals by 2H.

Further, the other ends of the gate buses v1 to vm are connected through TFTs 44, and are connected to the other ends of the gate buses φ1. φ2. 0N10FF control is performed by repeated pulses of φ3, and 0N10FF is controlled by two adjacent 0
N is given.

Let's focus on the second half 1H of FIG. 11 v1. At this time v2. v3
is also in Lebel and φ4. Since φ2 is also 1, Tvl,
Tv2 is ON. Therefore, Gate Bus v1. Even if there is a disconnection at one place each in v2, the data is transferred from v3 to Tv1 through Tvl and 'rv2. A scanning signal is given to v2. At this time, an image signal corresponding to the scanning line (gate bus) vl is transmitted.

(Figure 11 v1 diagonal line) When the second half of vl, 1H, is over, the TV
14OFF, v2. From v3 onwards, the detour will be blocked. Therefore, the correct signal is given either directly or via a detour.

In addition, especially when two gate pass lines are not disconnected in succession, it is sufficient that the scanning signal rises at 1H even if the rise is a little slow, and the W/
L may be small (W: gate width, L: distance between source and drain), which is advantageous in terms of design.

Embodiment 4 In Embodiment 3, a scanning pulse as shown in FIG. 12 is provided.

That is, a higher voltage is applied for the first 1H, and for the remaining 2H
delivers a scan pulse that results in the desired voltage.

By doing this, when the rise was slow, the time to reach a predetermined gate voltage became faster, and image unevenness was reduced.

Example 5 The TPT drive liquid crystal display panel 1 shown in the first Φ diagram was constructed of TPT whose main materials were polycrystalline silicon and silicon oxide. However, the difference between this display board and the conventional display board is that the TF of the display element
In addition to T42, there is a switch TP at the end of the display signal side bus.
T43 is also a switch TFT at the end of the scanning side bus bar.
44 are built at the same time, and even if these switch TFTs are not included, the switch TFT at the end of the signal bus line is also built in.
T43 is composed of pn complementary type. As a result, in the case of image display with gradation in Example 3, the problem of signal voltage drop across the TPT when passing through the switch TPT, which was a problem, was alleviated. According to the invention, the display device becomes popular. It is possible to improve image quality deterioration due to delay in signal transmission due to higher resolution. In addition, by using a mechanism for opening and closing a switch provided at the end of the electrode bus bar, correct display can be performed even if the electrode bus bar is broken, and a substantial improvement in yield can be expected.

In the embodiment of the present invention, an example of a scanning pulse of 1/4 of 3H at maximum is shown, but scanning pulses with a longer lead time are theoretically possible, and may affect the image depending on the display element. Adjustments should be made while observing. Further, although the present embodiment has been explained using an example of a liquid crystal display panel, there is no need to be limited thereto, and it is natural that the present invention can be applied to display panels generally driven by EL or other matrix types. It goes without saying that the present invention has similar effects even in the case of interlace.

[Brief explanation of drawings]

Fig. 1 is a timing chart explaining the display method of the present invention, Fig. 2 is a schematic diagram of an IJ hooks display device, and Fig. 3 is a diagram showing an example of a display unit of an IJ hooks display device. 4 and 6 are timing charts explaining the point-sequential method and line-sequential method, respectively. FIG. 6 is a diagram showing the scanning signals of the point-sequential and line-sequential methods. FIG. 7 is the scanning of the first embodiment of the present invention. A diagram showing signals, FIG. 8 is a diagram showing the overall configuration of a display device according to a second embodiment of the present invention, and FIG. 9 is a diagram showing an embodiment of the present invention.
. A diagram showing a scanning signal, FIG. 10 is a diagram showing the overall configuration of a display device according to the third embodiment of the present invention, FIG. 11 is a timing chart of the second embodiment of the present invention, and FIG. 12 is a diagram showing the scanning signal of the third embodiment of the present invention. FIG. 1... Electrode busbar for transmitting display signals, 2...
...Electrode bus for transmitting scanning signals, 3...Display unit, 4...Horizontal driver, 6...Vertical driver, 43...Display signal side bus End switch TFT, 44...Scanning signal side busbar end switch TFTO Name of agent: Patent attorney Toshio Nakao and one other person No. 1
Figure 2 Figure 3 Figure 4 ° Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 11 Figure 12

Claims (5)

[Claims] (1) A first electrode bus group for transmitting display signals, a second electrode bus group for transmitting scanning signals, and a display unit corresponding to the intersection of the first electrode bus line and the second electrode bus line. a display unit having a switch formed therein and driven by the two signals, wherein a start time of transmission of the scanning signal that turns the switch into a conductive state is transmitted to a group of display units intersecting the second electrode bus line. A display method characterized in that the display method is earlier than the time when transmission of a group of display signals to be displayed is started. (2) The scanning signal transmitted to the second electrode bus line should be transmitted to the display unit group that intersects the second electrode bus line, rather than the scan signal transmitted to the second electrode bus line that was scanned immediately before. 2. The display method according to claim 1, wherein the transmission is started with a delay of a display signal period. (3) Control the open/close switch provided at the end of the bus bar in order to transmit the signal transmitted from one end of the bus bar to the other bus bar, and apply the signal simultaneously and redundantly to a plurality of bus bars in at least one group of the bus bar groups. Claim 1 characterized in that
The display method described in Section 1 or Section 2. (4) The display method according to claim 1, wherein the switch is an insulated gate field effect transistor. (5) The display method according to claim 3, wherein the opening/closing switch is an insulated gate field effect transistor.