JPS62182718A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To make a device advantageous for enlargement of a picture by using a TFT formed on the same substrate as a liquid crystal cell to transfer an image by the BBD system. CONSTITUTION:An electrode substrate 2 consists of liquid crystal picture element rows 31-34 each of which is arranged in a single row, a driving circuit 45, and transfer circuits 46-49. Numbers and pitches of respective picture element electrodes 41-44 of liquid crystal picture element rows 31-34 are equalized. The driving circuit 45 switches picture element electrodes 41 in the first row by an external input signal, and transfer circuits 46-49 transfer picture signals of picture element electrodes 41 in the first row to picture element electrodes 42-44 in the second and following rows synchronously with an external clock pulse. The driving circuit 45 and transfer circuits 46-49 are formed with TFT on the same substrate as a liquid crystal.

Description

[Detailed Description of the Invention] Field of Application in CiA Industry] The present invention relates to a liquid crystal device, and in particular, a thin film transistor (
Packet brigade I.
- It relates to a liquid crystal display device using a device (charge transfer element, hereinafter referred to as 88 ports) type circuit.

[Summary of the Disclosure] The present application and drawings describe a liquid crystal display device using a BBD type circuit using TPT, in which liquid crystal pixel columns are arranged in multiple columns and rows on one side of a liquid crystal panel, and
An electric circuit device is interposed between the liquid crystal pixel rows, and image signals -J- for one scanning signal line are sequentially inputted from one side of the liquid crystal panel in a direction opposite to the liquid crystal panel. By temporarily interrupting the transfer when the image for one screen has been transferred and displaying the image by holding it for a fixed period of time, the display speed is faster and the number of wires is reduced compared to the conventional method. This makes it possible to reduce the amount by about half.

FIG. 10 is a schematic configuration diagram of a transmission type liquid crystal display device,
This figure shows the most basic configuration of a liquid crystal display device °jl according to the present invention. In FIG. 1O, the liquid crystal display device consists of electrodes on which transparent electrodes 3 and 4 are formed, plates 1 and 2 (in which a TPT circuit or an insulating layer is sunk depending on the case), and the electrodes sandwiched between the substrates. The liquid crystal panel IO is composed of a transparent liquid crystal layer 5, a liquid crystal panel IO roughly constituted by polarizing plates 6 and 7 arranged on the outside of the electrode substrate, and a light source 8.The liquid crystal panel IO is driven by the transparent electrode 3, The light emitted from the light source 8 is modulated by the liquid crystal layer 5 and displayed on the panel L.

On the other hand, the most practical driving methods when the electrode configuration of a liquid crystal panel is a matrix type include a simple matrix addressing method and an improved active matrix method.

FIG. 11 shows the electrode configuration of the simple matrix addressing method. This method consists of 8iX1 belt-shaped power lines arranged in a row,
X7, X3-... and the column 't[i&Y+, Y7
.

Y3... are arranged perpendicularly to each other, and a panel structure is formed in which liquid crystal is filled between both electrodes, and a voltage is applied between the selected row electrode and column electrode, and the The selected intersection point (for example, the shaded area in the figure) is displayed. This simple matrix addressing method has the disadvantage that when the number of pixels is increased, the contrast suddenly decreases, and many connections in the vertical and horizontal directions are not required, and driving circuits are required in each of the vertical and horizontal directions.

For example, if you try to display 30 screens per minute and 500 X2O3 connections, as with TV image display, the time it takes for one pixel to be selected is 83g5l.

Conventional nematic liquid crystals could not respond.

On the other hand, in the active matrix method, as shown in FIG. 12, a switching element f-11 such as a transistor is arranged for each pixel to directly drive the liquid crystal 12. In this system, even with a scanning pulse of 83g5, the charge supplied to the liquid crystal 12 can be held for 33m5 until the next scan due to the action of the switch element 11, and moving images can also be displayed. However, even with this active matrix method, the number of m is the same as before, 500
500 wires were required, and there were problems such as complicated wiring when the screen was enlarged.

The present invention has been made in view of the prior art described in L, and an object of the present invention is to provide a liquid crystal display device that has a high display speed and has a significantly reduced number of wire connections.

[Details for solving the problems] - Explaining the first stage for solving the problems described above using FIG. In a liquid crystal display device using a liquid crystal panel that modulates a liquid crystal display, liquid crystal pixel columns 31 to 34 are arranged in row f on one side substrate of the liquid crystal panel, and an electric circuit device is arranged between the liquid crystal pixel columns 31 to 34. 45 to 49 are interposed to sequentially transfer the image signals of one scanning signal line sequentially inputted from one side of the liquid crystal panel to the opposite direction of the liquid crystal panel indicated by +i to j, and to transmit the image signals of one screen. This is a liquid crystal display device characterized in that the image is displayed by temporarily interrupting the transfer when the transfer is completed and holding the image for a certain period of time.

In addition, the image signal transfer circuit uses TPT formed on the same substrate as the liquid crystal, and configures a BBD type circuit.
Image signals are sequentially transferred to each column of the liquid crystal panel.

[Sakukawa] When the transfer circuit is turned on and off in synchronization with the clock pulse, the charges in the liquid crystal cells in the front and rear stages move, causing t to appear on the image.
J is transferred sequentially. The liquid crystal is driven according to the transfer speed, and after the transfer, the transfer is interrupted for a certain period of time according to the human response time and the liquid crystal response time, and the image is retained.
Images are displayed at a display speed of 1■, which is the same as that of a TV screen. Furthermore, if TPT is used and data is transferred using the BBD method, the circuit configuration can be made more compact than in the conventional method, as is clear from FIG.

[Example] Example 1 FIG. 1 is a block diagram of a substrate showing a first example of the present invention, and shows a portion corresponding to the electrode substrate 2 in FIG. 1θ. In FIG. 1, electrodes, (the plate 2 has liquid crystal pixel rows 31 to 34 arranged in a single row, and a drive circuit 45,
It is composed of transfer circuits 46 to 49. LCD pixel row 3
The number and pitch of each pixel electrode 41 to 44 are the same in all columns. The drive circuit 45 opens and closes the pixel electrodes 41 in the first column according to external input signals, and the transfer circuits 46 to 49 synchronize the image signals of the pixel electrodes 41 in the first column 11 with external clock pulses. The data is sequentially transferred to the pixel electrodes 42 to 44 in the second and subsequent rows.

The drive circuit 45 and transfer circuits 46 to 49 described in ``2'' can be formed of TPT on the same substrate as the liquid crystal. FIG. 2 is a partial plan view showing an example of such a TPT pattern, and FIG. 3 is an equivalent circuit diagram thereof. In both figures, the drive circuit 45 and transfer circuits 48, 47, .
..., and as shown in FIG. +, 72.7
3... is connected. The image signal is input to the drive circuit 45 from the digital power terminal 74. The drive circuit 45 and the transfer circuits 48, 47, . . . : A source terminal 75 and a drain end T'78 are connected to the poles 41, 42, . Connected to the destination pixel electrode.

Therefore, the image signal input to the drive circuit 45 is applied to the electrodes 41 . Transfer circuit 461 pixel electrode 42. Transfer circuit 47・
... will be transmitted. Pixel electrodes 41, 42...
. . , and the counter electrodes 77, 78, . In this pixel section, transmitted light is modulated according to the voltage applied between the two opposing electrodes 41, 77, 42, 78, . . . . A gate signal line that synchronizes that modulation to an external clock pulse? 1, 72, 73, . . . , odd-numbered stages are connected to the first clock signal line CLK1, and even-numbered stages are connected to the second clock signal line CLK2. Also, the counter electrode of the liquid crystal cell? 7, 78, 79..., the first stage is connected to the constant voltage source v1, and among the second and subsequent stages, the odd number stages are connected to the first clock signal line CLK1, and the even number stages are connected to the second clock signal line CLK1. It is connected to the clock signal line CLK2.

FIG. 4 is a time chart showing the relationship between the timing and voltage of each signal 5J- of the circuit described in "2". Each pixel portion (LCn l+ to LC444) of the liquid crystal cell has a voltage (V
u-Vt) like 'lIΔ''! When the voltage is zero, “
It is assumed that the state is bright, and in the image signal (DATA), Vu (high voltage level) is the IIA signal, and 1 (low voltage level) is the bright signal. Also, GLKI and CLK
Similarly to the voltage level of the image value tJ, the high voltage level is Vll and the low voltage level is Vl.

Next, the operation of this embodiment will be explained based on FIGS. 3 and 4. It is assumed that all of the pixel sections of the liquid crystal cell are initially in the 'RtJ state, and that all the pixel sections of the liquid crystal cell are initially in the charged state.

First, the image signal input to the human power Shinsou end T-74 is C
When LK I reaches the high voltage level V((), the drive circuit 45
becomes on-state yE and is transmitted to the pixel electrode term of the first column [1. If the image transmitter is VH, the pixel section is in a charged state, and if it is Vl, it is in a discharged state. Since the clock signal 5) is a pulse, the CLK 1 immediately goes to the low voltage level Vl.
The drive circuit 45 is turned off, but the pixel section 41
The charge stored in the electrode 1 maintains the charged or discharged state of the cell even after I during the transfer.

Next, when CLK2 reaches the high voltage level Vll, the second stage TPT 4B turns on, and if the pixel section 411 in the first column in the previous stage is in the discharge state, the pixel section 411 in the second column
22, the pixel portions 411 in the first column enter a charged state, and the corresponding pixel portions 422 in the second column m+ enter a discharge state. At this time, the pixel portions 411 of the first column 11 that were in a charged state received no charge from the corresponding pixel portions 422 of the second column [1], and therefore the first column was in a charged state of 7 m. If so, the second column [1 will also be in the charging state. In this way, the image value is transferred from the pixel section 411 of the first column [1 to the pixel section 422 of the second column [1]. After that, CLK2 is returned to Vt, and the data transfer ends. .

(Please, when GLK I becomes Vll again, the second
Pixel unit 4 of 1] 422 charging/discharging status is in 3rd column] 1
33, all the pixel units 422 in the second column [1] are in a charged state, and the pixel units 433 in the third column [1] hold the image signal -.At this time, the TPT drive circuit of the first stage 1] 45
is also turned on, so the next image signal is sent to the signal input terminal T-
74 to the pixel portion 411 of the first column 11. With such two-phase clock pulses, by alternately setting CLK l, C1, and 2 to the high voltage level Vl+, 1 image value number is sequentially changed to 1 in the 2nd column from the pixel section 411 in the 1st column.
The subsequent image values are transferred by following the preceding image signals in the middle 1st column.
This is a method known as a device (charge transfer device).
“Philippus Technical Review Pa (”Ph1l
ipsTech, Review'') 1979, 3
Sangste on pages 97 to +10 of 1.
It was first proposed by Mr. R., F., L., J.), and the present invention is characterized in that it is configured with a liquid crystal cell and TPT to transfer image signals. .

Now, the transfer time for one image value number is the capacity C of each liquid crystal cell,
It is considered that it is almost determined by the on-resistance R of the transistor.

For example, if C = 1 pF and R = I MΩ, -
- The transfer time for a column can be set to about CR=17is. That is, when the number of pixels is about 500 x 2 O 3, the transfer time for one screen is about 0.5 ms, which is very fast. Therefore, by taking into account the response sensitivity of the two human eyes and the response time of the liquid crystal after the transfer, the next image is transferred for about 30 tms, so that the image of the autumnal equinox is displayed. Therefore, according to this drive method, it is possible to easily obtain about 30 moving images per second, which is the same as television images. Moreover, according to the circuit configuration shown in FIG. 3 described above, the number of connections is about half that of the conventional one, so it is advantageous for increasing the screen size. Further, since the charging/discharging pattern 7m of each pixel formed by transferring image values is maintained by stopping clock driving, a static IF image can be easily obtained.

Example 2 In the above example, the voltage applied to the liquid crystal cell is Vll
-VL or OV. In the commonly used twisted nematic type or birefringent type liquid crystal element T-, the "bright" state and I,,tSI
Since the T-shape yE is facetted, the above-mentioned application method may be used, but for example, in ferroelectric liquid crystals, a voltage with opposite polarity can be used to create a ``bright'' state and a ``dark'' state. Jj (For -, voltages of positive and negative iI+4 polarities must be applied.

FIG. 5 is an equivalent circuit diagram showing a second embodiment of the present invention. FIG. 5 shows an application example of the equivalent circuit shown in FIG. 3, in which the counter electrode of the liquid crystal cell and the gate signal line of the TFT are not directly connected, but a DC/Haas voltage 80 is provided. The other configurations are the same as in FIG. 3. In FIG. 5, the DC, <Iasumi pressure is V, and the input signal level is Vll,
As Vl, the voltage of the counter electrode of the first stage liquid crystal cell is VL
+V, the voltage applied to the liquid crystal is Vll-Vl −
V and one ■, please use ■! , IJ na (By casting 1 to Goi, you can obtain a neutral force of 1-do Ichikawa with both positive and negative polarity.

In ferroelectric liquid crystals, the response is the electric field strength (pulse strength)
and the application time (pulse width), and the response threshold is determined by the product of the electric field strength and the application time.

For this reason, by transferring the transfer cycle so that it is less than the rice pulse width, the LCD screen will not respond during the transfer, and after the transfer is completed, a time greater than the threshold will be secured, and the LCD screen for the screen will be cleared once. The image can be displayed on the panel in response to

Therefore, if ferroelectric liquid crystals are used, even during signal transfer,
You can see the previous image.

In addition, the number of videos per video is determined by the transfer speed, and the number of pixels is 500
500, it is also possible to print about 1000 sheets per second.

'X Example 3 FIG. 6 shows a display example when an image is displayed according to the above-described example. When image signals are transferred using the BBD method, the displayed columns are arranged with a difference of 7i every two columns, so an information blanker η is added to the image as shown in FIG.
will be included. Generally, it is known that on a display panel, if the area of the information blank row is not limited to about 10% of the entire screen, there will be only 11\γ blanks. Therefore, when the pixel density is low, the image may be difficult to view.

FIG. 7 shows an example of some of these problems, and is a cross-sectional view of a liquid crystal panel. In FIG. 7, each pixel has a three-layer electrode structure, and between each electrode are liquid crystals 501, 502. ...and lots of transparent dielectric materials without birefringence, 102. ...is being held in place.

In addition, the capacitance CLC between the electrodes sandwiching the liquid crystal and the capacitance I'LCp between the electrodes sandwiching the transparent dielectric material are large, and they are configured so that the top and bottom are opposite to each other in the image transfer direction. . Furthermore, the gate clock signal for upper layer transfer and the gate clock signal for lower layer transfer are alternately connected from CLK1 and CLK2 as shown in FIG. In the second configuration, the image signal is transferred from the CLC to the adjacent CD and then to the adjacent CLC. At this time, the transfer cycle of the upper layer and the transfer cycle of the lower layer are in reverse phase, so at the end of the transfer, that is, when the display time begins, the 4-lower information blank column is overlapped with the information display column of the other layer. After being supplemented, all pixels display significant information.

Embodiment 4 FIG. 8 shows an example of several pieces of the problem of the information blanker 1, similar to the above-mentioned embodiment 3. In order to solve the problem of information blank rows in the cylinder, the part corresponding to the blank should be made as narrow as possible.

However, if it is simply made narrower, the required capacity is 71Y.
You won't be able to get enough money. Therefore, by filling the portion corresponding to the blank with a dielectric material having a dielectric constant about 10 times that of the liquid crystal, it is possible to suppress the area of the information blank row to about 10% of the display area. In FIG. 8, 81 is a glass substrate, 82 is an alignment film, 83 and 87 are pixel electrodes, 84 and 86 are signal lines that supply clock signals to the gates of TFTs, 85 is an electrode narrower than the pixel electrode, 88 is a liquid crystal, and 89 is a dielectric. Between the pixel electrodes 83 (83a) and 87 (87a), an electrode 85 (85a) having a narrower width than the pixel electrode is arranged.
A dielectric material 89 is filled between the electrodes. Here, the capacitances between the pixel 'iti, the poles 83 (83a), 87 (87a), and the electrode 85 (85a) are all configured to be equal. With such an electrode configuration, the signal charge stored in the pixel electrode 83 (83a) is
A clock signal on line 84 causes electrodes 85 .
85a and the dielectric 89, and then transferred to the pixel electrode 87 (8?a) by the clock signal on the signal line 86. Therefore, it is possible to narrow the blank portion without increasing the capacitance j11 by i+f.

In this embodiment, the dielectric 89 can also be used as a camp spacer for the liquid crystal cell.

Example 5 This example is an application example of Example 4 described above, and is configured so that the camp length between the upper electrodes is narrowed. FIG. 9 shows an example of this, and in the same figure, a conductive member 90 is laminated on 1- of the electrode 85a in order to narrow the cell gap. Other configurations are as described in the 8th section above.
This is the same as Embodiment 4 in the figure. Even with such an electrode configuration, the same effects as in Example 4 described in h can be obtained.

[Effect of the invention] The present invention has the following special effects of first order.

(Since the TPT formed on the same substrate F as the liquid crystal cell is used and the image is transferred using the BBD method, the number of connections on the panel can be reduced to approximately 2000 times that of the conventional matrix method, and one circuit can be made simpler.Therefore, it is advantageous when increasing the screen size.

(2) Since there is only one signal J line between adjacent pixel columns for data transfer and lock belief, one matrix of signal electrodes is required in each row and column. The opening 1-1-4 can be made higher than in the normal matrix method.

(3) By using a ferroelectric liquid crystal with memory properties, a static IF image can be displayed in one transfer, and a moving image can be easily displayed at a distance of 1 meter. Also, the number of pixels is 5
On a 00 x 500 screen, it is possible to display moving images at a high display speed of about 1000 images per second. Furthermore, in ferroelectric liquid crystals, it is possible to obtain moving images with no flickering at all by controlling the threshold value by the pulse width.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a board showing the first embodiment, Figure 2 is a T
A partial plane view showing an example of the PT pattern, Fig. 3 is its equivalent circuit diagram, Fig. 4 is a time chart showing the relationship between timing and voltage of each signal, and Fig. 5 is an equivalent circuit showing the second embodiment. 6 is an example of image display, FIG. 7 is a sectional view of a liquid crystal panel showing the third embodiment, FIG. 8 is a sectional view of a liquid crystal panel showing the embodiment of FIG. 4, and FIG. A cross-sectional view of a liquid crystal panel showing the fifth embodiment, FIG. IO is a schematic configuration diagram of a transmission type liquid crystal display device, FIG. FIG. 3 is a diagram showing an electrode configuration. 31-34...Liquid crystal pixel row, 41-44...pixel electrode, 45...drive circuit, 48-49...transfer circuit,
71-73... Gate signal line, 74... Image input terminal. 75...source terminal f, 7B...drain terminal,
77-79... Counter electrode, 411-444... Pixel portion.

Claims (1)

[Scope of Claims] 1) A liquid crystal device using a liquid crystal panel that modulates light using an electro-optic effect, comprising: a plurality of liquid crystal pixel columns arranged in a plurality of columns; and an electric circuit interposed between the liquid crystal pixel columns; Sequentially transferring image signals for one scanning signal line sequentially input from one side of the liquid crystal panel to a direction opposite to the liquid crystal panel,
1. A liquid crystal device comprising means for temporarily interrupting the transfer of image signals for one screen when the transfer is completed and holding the transfer for a certain period of time. 2) The image signal transfer circuit is characterized by using thin film transistors formed on the same substrate as the liquid crystal, configuring a bucket bridge element type circuit, and sequentially transferring image signals to each column of the liquid crystal panel. A liquid crystal device according to claim 1. 3) By using a ferroelectric liquid crystal as the liquid crystal and setting the transfer speed so that the image signal transfer cycle is less than the threshold pulse width of the ferroelectric liquid crystal, the liquid crystal on the screen does not respond during transfer. Claims 1 or 2, characterized in that the image is displayed by ensuring a time equal to or more than a threshold value after the completion of the transfer and causing one screen of liquid crystal to respond at once.
The liquid crystal device described in section. 4) A pixel row composed of a glass substrate, a transparent electrode, a transparent dielectric, a transparent electrode, and a glass substrate in this order, and a pixel column composed of a glass substrate, a transparent electrode, a transparent dielectric, a transparent electrode, a liquid crystal, a transparent electrode, and a glass substrate in this order. If the pixel rows are arranged alternately via thin film transistors, and the capacitance between the transparent electrodes that sandwich the liquid crystal is C_L_C, and the capacitance between the transparent electrodes that sandwich the transparent dielectric is C_D, image information can be Claims 1 to 3 are characterized in that the data is transferred from the C_L_C to the adjacent C_D and then to the adjacent C_L_C so that the upper layer transfer cycle and the lower layer transfer cycle are in reverse phase. The liquid crystal device described. 5) Among the capacitances of the bucket brigade element that transfers image information, the n-th capacitance is composed of two upper and lower electrodes, at least one of which is transparent, sandwiching the liquid crystal, and the n+
Claims 1 to 4 are characterized in that the first stage capacitance is composed of an electrode having a smaller area than the electrode forming the n-th stage capacitance. liquid crystal device.