JPH03233517A - Image converter - Google Patents

Abstract

PURPOSE:To allow the easy restoration of images and the displaying with fewer signal lines by disposing plural kinds of the picture element unit groups constituted of plural pieces of picture elements on a substrate and forming these groups in such a manner that one piece of the picture element is subjected to driving control by being attributed simultaneously to different kinds of the picture element unit groups. CONSTITUTION:The many 1st picture element units constituted of plural pieces of the picture elements are disposed on a lower substrate side and the many 2nd picture element units varying from these 1st picture element units are also disposed. These units are so constituted that one piece of the picture element is subjected to driving control by being attributed simultaneously to these different picture element unit groups. Namely, two kinds of the picture element unit groups; the picture element unit 1a... group belonging to the odd lines and rows in, for example, data lines 5 and address lines 6 and the picture element unit 1b... group belonging to the odd lines and rows, are respectively disposed in the form of a matrix. The constitution in which one piece of the picture element is subjected to driving control by being attributed simultaneously to these different picture element unit groups is adopted. The display defects are relieved in this way and the displaying with the fewer signal lines is possible. In addition, the easy and sure control of gradation characteristics is possible as well.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image conversion device for driving and controlling each pixel of a video display such as a flat panel display.

2. Description of the Related Art In recent years, with the advancement of information technology, in the field of displays for displaying images, there has been a desire for displays with higher definition and higher brightness.

The second type of display currently used in home and other fields is CRT (Cathode Ray T).
Cathode ray tube (UBE) type displays are the mainstream, but there is an increasing demand for flat panel displays that are smaller, lighter, have lower power consumption, and can provide higher image quality.

Among flat panel displays, liquid crystal displays that use liquid crystals (!:1quid Crystal !2
isplay:LCD1 is currently the most widely used,
It is a display with great future potential.

Examples of driving methods for this LCD include a simple matrix driving method and an active matrix driving method. and,
Among these, the active matrix driving method is a method in which an active element is provided for each pixel and each pixel is independently driven and controlled. Therefore, in principle, 1
It is possible to drive at a duty ratio close to 0.00%, and it is possible to increase the contrast ratio of pixels.

Further, as the active element, for example, polycrystalline Zinocon (
Poly-5i) and amorphous silicon ('a-5
Thin film transistor using i:H1
mTransistor; TFT). This TPT has a relatively low temperature (300°C to 600°C).
), it can be formed on a transparent substrate such as a quartz or glass substrate, and has the advantage that the continuous film formation maintains the cleanliness of the film interface.

Next, a conventional TFTLCD will be explained.

FIG. 10 is a plan view of the main part of the lower electrode substrate 50 adopting the active matrix driving method, and FIG. 11 is a TFTLC.
FIG. 12 is a front sectional view of the main part of D, and is a circuit diagram schematically showing the outline of the active matrix circuit.

As shown in FIGS. 10 and 11, the lower electrode substrate 5
0, on the upper surface of the first glass substrate 51, a large number of data lines 52 . ...and address line 53...
- Near which intersection is the TFT 54... formed?

As shown in FIG. 11, the TFT 54 has a gate electrode 5.
5 and the drain electrode 56 and source electrode 57, a gate insulating layer 58, a semiconductor layer 59 made of a-5i+H,
It is constructed by sequentially stacking ohmic contact layers 60. The address line 53 is the gate electrode 5
Further, the data line 52 is connected to a drain electrode 56, and the source electrode 57 is connected to a pixel electrode 61 formed on the gate insulating layer 58.

An upper electrode substrate 62 is disposed above the lower electrode substrate 50, and the upper electrode substrate 62 includes a counter electrode 63 made of a transparent material and a second glass substrate 64.

Further, a twisted nematic liquid crystal layer 65 is formed between the lower electrode substrate 50 and the upper electrode substrate 62, and the first glass substrate 5
Polarizing films 66 and 67 are attached to the lower surface of the glass substrate 1 and the upper surface of the second glass substrate 64 to control the polarization of incident light.

Further, the data line 52 and address line 53 are connected to a signal voltage drive circuit 68 and a gate voltage drive circuit 69, respectively, as shown in FIG.

In the TFTLCD configured in this way, image display is performed according to the following principle. That is, a gate voltage is applied from the gate voltage driving circuit 69 to the address line 53, and a train voltage is applied from the signal voltage driving circuit 68 to the data line 52. As a result of (2), a source voltage is applied to the pixel electrode 61 side, an electric field is generated between it and the counter electrode 63, and the alignment direction of the liquid crystal in the liquid crystal layer 65 changes. By changing the orientation of the liquid crystal, the transmitted light is turned on and off, and an image is displayed. In the TFTLCD, a desired image is displayed by sequentially scanning all the address lines 53 . . . and all the data lines 52 . . . using the driving method described above.

Problems to be Solved by the Invention As mentioned above, the TFTLCD drives each pixel by scanning the address line 531 and the data line 52 and turning on and off the TFTE 54. Therefore, there is a defect (malfunction) in the TFT 54... or the data line 52... or the address line 53...
If a disconnection or the like occurs, the pixels at the defective location or the pixels on the disconnected line will become a display defect. If such a display defect occurs in the TFTLCD, this TF
This means that the TLCD cannot fully function as a display device.

Therefore, it is desired to manufacture an LCD in which these display defects do not occur over all pixels. In particular, L.C.
It is inevitable that D will become larger in area and higher in image quality (higher definition) in the future, and it is necessary to repair defective parts in the substrate and manufacture LCDs that ensure sufficient display performance. has become a major issue.

In addition, in the above LCD, the gradation display that changes the density of the display screen in steps is achieved by changing the gate voltage or drain voltage applied to the TFTs 54 in steps.
This is done by controlling the drain current flowing through T54... However, when performing high gradation display, the maximum voltage applied to the TPTs 54 becomes high. Therefore, the threshold voltage of the TFTs 54, etc. fluctuates, and the characteristics of the TFTs 54 become unstable, making it difficult to control gradation display.

Furthermore, in the above LCD, increasing the pixel density and the number of signal lines can be considered as a means of realizing a high-definition screen. Since the amount of information inevitably increases when the number of signal lines is increased, the signal voltage drive circuit 68,
It is required that the gate voltage drive circuit 69 or the TFT 54 operate at high speed. However, there is a problem in that it is not possible to sufficiently increase the speed of the signal voltage drive circuit 68, gate voltage drive circuit 69, or TFT 54 due to wiring resistance in the circuit.

The present invention has been developed in view of the above problems, and is capable of resolving display defects, displaying clear images with improved gradation, and speeding up operation without increasing the number of signal lines. The purpose of the present invention is to provide an image conversion device that can convert images into images.

To solve the hard work! In order to achieve the above object, an image changing device according to the present invention includes a plurality of first pixel units each including a plurality of pixels disposed on the lower substrate side, and a different number of first pixel units from the first pixel units. A large number of second pixel units are also arranged,
It is characterized in that one pixel belongs to these different pixel unit groups at the same time and is driven and controlled.

■ According to the above configuration, multiple types of pixel unit groups each consisting of a plurality of pixels are arranged on the substrate, and one pixel simultaneously belongs to different types of pixel unit groups and is driven and controlled. Display defects can be repaired, display can be performed with fewer signal lines, and gradation can be controlled easily and reliably.

roundabout Embodiments according to the present invention will be described below based on the drawings.

In FIG. 2, l indicates one pixel unit, and this pixel unit 1 has four pixel electrodes 2a to 2d arranged in a square shape and is arranged at the center between these pixel electrodes 2a to 2d. The first MOS FET (M
etal Oxide Sem1conductor
Field Effect Transistor 3
It is composed of:

Further, the first MOSFET 3 is connected to each of the pixel electrodes 2a to 2d via its source electrode (not shown). That is, the first MOSFET 3 and the four pixel electrodes 2a to 2d are connected in a substantially X shape.

Each pixel corresponding to one pixel electrode 2a... was constructed with a liquid crystal cell, and the experiment was conducted. The pixels are T inside the liquid crystal cell body.
An N-type liquid crystal is built in, and each pixel is formed so that the substrate size is 20 mm x 20 mm, the gap is 8 μm, and the effective display area size is 15 mm x 15 mm.

The liquid crystal used has a dielectric anisotropy Δε=+3 and a refractive index anisotropy Δn=0.13.

In the pixel unit l configured as shown in FIG.
When a predetermined voltage is applied to the MOSFET 3, the four pixel electrodes 2a to 2d are driven simultaneously.

FIG. 1 is a schematic plan view showing an embodiment of the lower substrate side of the image conversion device according to the present invention.

This image conversion device has a large number of pixel units arranged in a matrix in a plan view, and a large number of data lines (signal lines) on both sides of the pixel electrodes 2a in the vertical direction. )5... are arranged, and a large number of address lines (signal lines) 6... are arranged in the horizontal direction perpendicular to the data lines 5....

Further, between the pixel units and the data line 5
. . . and the address line 6 . . .
OSFET (second active element) 7... are arranged. Furthermore, the train electrodes of the first and second MOSFETs 3.7 are connected to the data line 5, respectively, and the gate electrodes of the first and second MOSFETs 3.7 are connected to the address line 6, respectively.

Then, as shown in FIG. 3, the second MOSFET 7
Considering that the center is the four pixel units l'a, l
a, 1'b, and 1b are connected to each other to form a pixel unit pattern 8. Then, a signal is applied to the data line 5 and the address line 6, and the second
When the MOSFET 7 is activated, the four pixel units 1a, 1a, 1b, and 1b of the pixel unit pattern 8 are simultaneously driven.

That is, in the data line 5 and the address line 6, the pixel units 1a... group belonging to odd-numbered matrices (connections are indicated by black circles in the figure) and the pixel units 1-1b... group belonging to even-numbered matrices (in the figure 2 with white circles indicating connections)
f! W-m pixel unit groups are arranged in a matrix, and one pixel belongs to each of these different pixel unit groups at the same time and is driven and controlled. In other words, these pixel units 1a..., lb.
... are arranged vertically and horizontally so that a part of the pixel unit 1a ... and a part of the pixel unit 1b ... overlap. For example, in the figure, a pixel unit belonging to the fourth address line 6 from the top and the fourth data line 5 from the left (such address display is written as (4, 4)) has four pixel electrodes 2a...・In the figure,
The pixel electrode 2d located at the upper right is configured to overlap the pixel electrode 2b located at the lower left in the figure, which belongs to the pixel unit (3, 5).

Furthermore, the gradation of a pixel is proportional to the drive current flowing through the MOSFET. Therefore, the pixel driven by the operation of the second MOSFET 7 is driven by the operation of the first MOSFET 3.
Its contrast ratio is 1 compared to the pixel driven by
/4. That is, the pixel unit 1 shown in FIG.
Comparing the gradation (contrast ratio) between the case where is driven by the first MOSFET 3 and the case where the pixel units La, la, lb, 1b shown in FIG. 3 are driven by the second MOSFET 7, the latter is 1/4 of the former. Furthermore, in the pixel unit pattern 8, the second MO
Since the pixels located near the SFET 7 overlap each other as described above, the intensity of gradation is twice as high as that of the pixels located around it.

In addition, in FIG. 1, the pixel unit 1 driven by the first MOSFET 3 arranged at (4, 4) is (
An image is also displayed by driving the first or second MOSFET 3.7 other than the first MOSFET 3 of 4 and 4). In Table 1, the portions corresponding to the pixel electrodes 2a, 2b, and 2C12d are 7Th'l05FET3.
7 is shown.

Table 1 As shown in Table 1, pixel electrodes 2a, 2b, 2C
12d indicates that even if the MOSFET 3 at (4, 4) fails, when the surrounding MOSFET 3.7 is activated, images are displayed at the locations corresponding to these pixel electrodes 2a, 2b, and 2C2d, and the display defect is repaired. becomes. In addition, when all MOSFETs 3.7 operate normally, the pixels are driven in a superimposed manner, and the MOSFETs
The gradation of the pixel can be changed in various ways and the gradation can be controlled using only the binary signal of the on/off signal to the ET3.7. In other words, the pixel contrast is MOS F
This means that it can be changed depending on the density of pixels involved in driving the ET 3.7.

In the image conversion device according to this embodiment, pixels are driven by a mechanism similar to a neural network model, and images are displayed.

As shown in FIG. 4, the neural network model consists of a large number of input signals X1. When X 2...xo is input to the calculation unit 9, this calculation unit 9 calculates f=ΣWi
The calculation of X+ (i=1.2,...,n) is performed,
This is a model configured such that when the value of a function f exceeds a certain threshold, an output signal y is generated according to a fixed input/output characteristic of a numerical number f, and wl represents a weighting coefficient. In this example, the liquid crystal constituting the pixel has an applied voltage-transmittance characteristic as shown in FIG. do.

In other words, in the above neural network model,
The input signal X is connected to the MOSFET 3 to the pixel electrode 2a...
．． 7, and the output signal y corresponds to the contrast ratio of the displayed pixel 2.

Further, the weighting coefficient W corresponds to the potential at the pixel electrode 2a... that has increased due to driving of itself or the peripheral part, and the weighting coefficient W corresponds to the potential at the pixel electrode 2a...
corresponds to the applied voltage-transmittance characteristic. That is, the transmittance changes in accordance with the applied voltage, and when the potential of a certain pixel exceeds the dark value voltage V1, that pixel is turned on.

Furthermore, the gradation of the driven pixel is controlled by the voltage value of the applied voltage. Address line 5 like this
Even if the gate voltage and drain voltage applied to the data line 6 are on/off binary signals, the pixels can be displayed with various gradations.

Figures 6 to 9 show MOSFET 3.7 at a specific address.
FIG. 3 is a diagram showing a specific example of a display pattern when a driving pulse voltage is applied to the display pattern. In addition, the drive pulse voltage of MOSFET3.7 is gate voltage 4μ, drain voltage ±
Set to 2v, drive frequency to 30)(z, pulse width to 1
This was done by setting m5ec.

Figure 6 shows (3, 4) (4, 4) (5, 4) (4, 3) (
4 and 5) are driven. That is, (3,4)(5,4)(4,3)(4
, 5) shows the case where the pixel unit pattern 8 shown in the third section is driven, and the pixels shown in the shaded area in FIG. 7(a) are driven. Also M
The four pixels near the OSFET 7 have a contrast ratio twice that of the surrounding pixels because the pixel units overlap each other. Also, MOSFET3 of (4,4)
7 shows a case where the pixel unit l shown in FIG. 2 is driven, and the pixels shown in the shaded area in FIG. 7(b) are driven. FIG. 6 shows numerically the gradation intensity of each pixel when all of these pixels are driven and overlapped. In the figure, a portion surrounded by a black frame indicates a display pattern displayed on the display screen. As is clear from FIG. 6, even though the signal voltage is a binary signal of on/off, a display pattern with a gradation intensity of 1.2.3.7 can be displayed as an image.

Figure 8 shows (4, 7) (8, 7) (6, 5) (6, 9) (
This figure shows a display pattern when the MOSFETs 7 (indicated by square marks in the figure) are driven, and a substantially circular display pattern is displayed on the display screen according to the same principle as described above. The gradation display in this case is a two-gradation display of β tone intensities 1 and 2.

Also, Figure 9 shows (3, 6) (9, 6) (6, 3) (6,
9) (indicated by a square in the figure) shows a display pattern when a voltage is applied to the MOSFET 7. In this case, the image is displayed in a substantially circular shape, and the state in which the pixel unit patterns shown in FIG. 3 are independently driven is displayed as an image.

In this way, in the above embodiment, the pixel unit 1 consisting of a plurality of pixels is connected to the first and second MOSFETs 3.7.
Since each pixel electrode 2a...
can be driven by multiple MOSFETs 3...7..., display defects can be repaired, and deterioration of display characteristics can be prevented.
Even if it is a value signal, it is possible to display various gradations.

Also, address line 5... and data line 6...
The number of MOSFETs 3..., 7... disposed at the intersections is not limited to one. for example,
four MOSFETs are provided at the one intersection;
These MOSFETs may be connected to respective pixels, and the pixels may be configured to be driven by the respective MOSFETs.

Furthermore, in the above embodiment, the active element is a MOSFET.
Although an example is shown in which the active element is composed of TPT, the active element may be composed of TPT.

Further, in the above embodiment, MOSFETs 3... are placed at each intersection of the address lines 6... and the data lines 5...
Alternatively, MOSFET 7... is arranged, and these MOSFETs 3.
..., 7... drive and control a plurality of pixels, but instead of the MOSFETs 3..., 7..., each intersection of the address line 6... and the data line 5... It is also possible to draw out lead wires from the pixel, connect these lead wires to a drive control mechanism having a switching function, and drive each pixel via the drive control mechanism.

In this way, the lead wires are connected in place of MOSFETs 3..., 7..., and the drive control mechanism is used as shown in FIGS.
When an alternating current voltage of ±4 square meters was continuously applied to the same location as in FIGS. 6, 8, and 9, display patterns similar to those in FIGS. 6, 8, and 9 were obtained.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified within the scope of the invention. For example, the shape of the pixel is not limited to a square shape, and may be a rectangular shape or any other shape. However, in order to efficiently arrange the pixel units, a square or rectangular shape is desirable.

Furthermore, the material constituting the pixel is not limited to liquid crystal materials, and other charge-emitting materials having a threshold voltage, such as light emitting diodes (LEDs), can also be used.

As a comparison example, we manufactured the LCD mentioned in the "Prior Art" section, that is, TFTLCD (see Figures 10 to 12), and used the addresses specified in Figures 6, 8, and 9. A voltage was applied to the TPT at the same position as that of the first one, and the contrast ratio was measured. The contrast ratio was 20. The gate voltage was set to ±15■ when on and O■ when off, and the drain voltage was set to ±1O■ when on and 0■ when off. Also,
The driving frequency was set to 30Hz.

In this comparative example, only one TPT is provided for each pixel, and the input signal is a binary signal of on/off, so if the gate voltage and drain voltage are the same, a constant train Only current is obtained, and the contrast ratio remains constant. In other words, in this comparative example, each TP
Only one pixel connected to T is driven by one TPT, and the pixel is not driven by the TPTs in the periphery, so the contrast ratio of the pixel depends on the voltage values of the gate voltage and the drain voltage. I will do it.

Further, in this comparative example, the defective pixel is not repaired.

Effects of the Invention As is clear from the above description, the image conversion device according to the present invention has a plurality of types of pixel unit groups each composed of a plurality of pixels arranged on a substrate, and one pixel is a pixel of a different type. Since they belong to a unit group and are driven and controlled at the same time, defective pixels can be repaired, images can be easily restored, and display can be performed using fewer signal lines.

Furthermore, even if the input signal is a binary signal of on/off, it is possible to display various gradations with high definition.

As described above, the image conversion device according to the present invention can perform desired gradation display without complicating the device such as increasing the number of signal lines, and can also repair pixel display defects. can.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing an example of the lower substrate side of the image conversion device according to the present invention, FIG. 2 is a schematic plan view showing an example of a pixel unit, and FIG. 3 is an example of a pixel unit pattern. FIG. 4 is a schematic plan view for explaining an example of the operating principle of the image conversion device according to the present invention, and FIG.
The figure is a characteristic diagram showing an example of applied voltage-transmittance characteristics of liquid crystal.
FIG. 6 is a plan view showing an example of the display pattern, and FIG.
)(b) is a plan view for explaining the display principle of the display pattern in FIG. 6, FIG. 8 is a plan view showing another example of the display pattern, and FIG. 9 is a plan view showing yet another example of the display pattern. 10 is a plan view showing the main parts of the conventional example, FIG. 11 is a front sectional view showing the main parts of the conventional example, and FIG. 12 is a signal circuit diagram showing the conventional example. l... Pixel unit, 2a, 2b... Pixel electrode.

Claims (1)

[Claims] (1) A large number of first pixel units composed of a plurality of pixels are arranged on the lower substrate side, and a large number of second pixel units different from these first pixel units are also arranged, and one An image conversion device characterized in that pixels belonging to these different pixel unit groups at the same time are driven and controlled.