JPH07327236A - Television receiver - Google Patents

Abstract

PURPOSE:To improve yield as the whole of a device by using the optical shutter consisting of three or more liquid crystal compositions as the means which changes the color of light with time. CONSTITUTION:A PTFT 13 is provided in the intersection part between a first scanning line 5 and a data line 3, and a PTFT for another picture element is provided in the intersection part between the first scanning line 5 and a data line 4. Meanwhile, an NTFT is provided in the intersection part between a second scanning line 8 and the data line 3. AD NTFT 22 has the input end of a drain 20 connected to the second scanning line 8 through a contact and has a gate 21 connected to the data line 3 and has the output end of a drain 18 connected to a picture element electrode 17 through a contact in the same manner as the PTFT. Thus, one pixel is constituted of a picture element 17 consisting of a transparent conductive film, the PTFT 13, and a C/TFT consisting of the NTFT 22 between the pair of scanning lines 5 and 8. This constitution is repeated in vertical and horizontal directions to obtain a large- picture element liquid crystal display device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention specifically relates to a video signal transmitted from a terrestrial television station, a satellite television station, a cable television station or a television image recording device (a video deck, a laser disc, a magneto-optical disc, etc.) provided individually. We propose a device to display. It can also be applied to the viewfinder of video cameras.

[0002]

2. Description of the Related Art Conventionally, as a device for concretely displaying a video signal transmitted from a terrestrial television station, a satellite television station, a cable television station, or a television image recording device (a video deck, a laser disc, a magneto-optical disc, etc.) provided individually. Has adopted a method in which an electron beam is blown in a vacuum tube called a cathode ray tube or a CRT to cause a fluorescent surface as an object to emit light.

Initially, the diagonal of the display body was often 12 to 14 inches, but in recent years, the size of 20 inches, not to mention 30 inches, has come to appear due to the demand of the world.

When the diagonal is 30 inches, the depth is about 30 inches, and the thickness of the glass forming the glass exceeds 1 cm in order to maintain the strength. Further, as another device, a method of enlarging and displaying a high-luminance CRT by an optical system and projecting it on a screen has been proposed, and is used for a large display area. The outline of the configuration is shown in FIG.

[0005]

In the case of a television receiver using a cathode ray tube, when the display surface exceeds 30 inches, the total weight is over 100 kg. In general households, it is difficult to place a heavy load exceeding 100 kg unless the place is limited. Moreover, when the layout is changed, it becomes difficult to move the weight manually, which hinders the spread of the weight to general households.

Therefore, a projection type television receiver has been proposed to solve the weight problem, but there is a limit to the improvement of the brightness of the original high brightness cathode ray tube, and the brightness itself on the enlarged screen is very low. Was becoming. Therefore, not only the screen is dark, but also the contrast ratio in the front is high because the image is magnified by the optical system, but the contrast ratio from the oblique direction is much inferior to that of the cathode ray tube method. However, in terms of weight, this method requires only about 50% of that of the cathode ray tube method, which is one of the solutions to the problem. The projection television 2 of FIG.
01 is a CRT or liquid crystal display device 204, a tuner 205, an optical system 203, a reflector 202, a screen 206.
Consists of.

[0007] In recent years, an example in which a thin film transistor type liquid crystal panel using amorphous silicon is used as a display body which is a base thereof instead of a cathode ray tube is often proposed. FIG. 2 shows a structural diagram according to those examples extracted from the patent specification. The weight is about 30% of that of the cathode ray tube method, which is one of the factors that help popularization in general households. However, the display brightness is still lower than that of the cathode ray tube method, and studies are under way to increase the intensity of the light source. However, when the intensity of the light source is increased, when the temperature of the liquid crystal panel rises and the thin film transistor is turned off due to light irradiation, The reality is that satisfactory display cannot be performed due to the decrease in the resistance value at. FIG. 3 shows a conventional active array. In addition, in order to simplify the description, the matrix is shown in a 2 × 2 matrix. A plurality of gate lines G _{1 and} G ₂ and a plurality of data lines D _{1 and} D ₂ are arranged orthogonally to each other, and pixel display elements are provided at intersections of the matrix. This pixel display element is composed of a liquid crystal section 102 and a TFT section 101.
Signals are applied to the respective pixels from the peripheral circuits 106 and 107, and predetermined pixels are selectively turned on or off to perform display.

However, when these liquid crystal display devices are actually manufactured and displayed, the voltage V _LC of the output of the TFT, that is, the input (called liquid crystal potential) to the liquid crystal is often
When it should be "1" (High), it does not become "1" (High), and
Conversely, when it should be "0" (Low), it does not become "0" (Low). This is a switching element that adds a signal to the pixel, that is, TF.
This occurs because the characteristic of T101 has no symmetry. That is, the state of charging and the state of discharging of the pixel electrode has a bias in terms of electrical characteristics. The liquid crystal 102 is essentially insulating in its operation, and the TFT 101
When is off, liquid crystal potential (V _LC ) is in a floating state. Since this liquid crystal 102 is equivalently a capacitor, V _LC is determined by the charges accumulated therein. This charge causes the liquid crystal to have a relatively small resistance at R _LC , leaks due to the presence of dust and ionic impurities, and causes R _GS when pin holes in the gate insulating film of the TFT cause R _GS. The charge leaks from V _LC , and V _LC is in a halfway state.
Therefore, in a liquid crystal display device having 200,000 to 5 million pixels in one panel, there is a problem that a high yield cannot be achieved.

Further, when color display is performed in any of the embodiments as shown in FIG. 2, since three or more active matrix type display devices are used as display bodies, a low yield can be raised to the third power. As a result, the overall yield was very low, and the cost was high.

[0010]

Therefore, according to the present invention, the color of light is temporally arranged on an optical path formed by one or more first liquid crystal devices for displaying a television image, a light source of the device, and a projection place. In a television receiver that changes and displays color, an optical shutter composed of three or more sheets is used as a means for temporally changing the color of light, and the liquid crystal composition exhibiting ferroelectricity is used as the optical shutter. It is characterized by using things.

That is, one color screen is composed of three or more screens, a red screen among the three primary colors of light is used as the first screen, and a green screen among the three primary colors of light is used as the second screen. A blue screen, which is one of the three primary colors of light, is displayed as a third screen, and display is made possible by synthesizing the time-series light reflected by the human eye.

It is known that human eyes can be accepted as a natural moving image by constructing 30 or more screens per second on average, although there are individual differences in their ability. Therefore, by displaying the three screens of the red screen, the green screen, and the blue screen in order within 1/30 seconds, color display becomes possible.

When the above display is performed, the time for displaying one color is 1 / (30 screens × 3 colors) = 1.11.
11, which is about 11 msec. Considering the display quality, it is necessary to use an optical shutter that causes a change in transmittance (bright to dark or dark to bright) within a few% of the display time.

Therefore, the present invention is characterized by using a liquid crystal composition exhibiting ferroelectricity as those optical shutters. Table 1 shows the transmittance change time (response speed) of the optical shutter using various liquid crystal compositions. As is apparent, it is understood that the only liquid crystal composition which exhibits the ferroelectric property satisfies the present invention.

According to the present invention, the number of the first liquid crystal device having a low yield can be reduced to one, and the yield of the entire device can be improved. Further, by using a liquid crystal composition exhibiting ferroelectricity as the optical shutter, it is possible to sharpen the color change and improve the image quality. Examples will be shown below, and further detailed description will be added.

[0016]

EXAMPLE In this example, a liquid crystal display device using a ferroelectric liquid crystal (FLC) will be described by using a liquid crystal display device having a circuit configuration as shown in FIG. 4, that is, an inverter type circuit configuration. FIG. 5 shows an actual arrangement configuration of electrodes and the like corresponding to this circuit configuration. For simplicity of description, only the portion corresponding to 2 × 2 is shown. The actual drive signal waveform is shown in FIG. In order to simplify the explanation, the explanation will also be made on the signal waveform in the case of the 4 × 4 matrix configuration. In addition, the specific arrangement of the liquid crystal device is shown in FIG.
As shown in FIG. 3, a first device (80) and three second devices (81) are provided, and a color filter (83) corresponding to R: G: B is provided between each of the second devices and the light source. It is provided in.

First, a method of manufacturing the liquid crystal display device used in this embodiment will be described with reference to FIGS. In FIG. 7A, the blocking layer 5 is formed on the glass 50, such as quartz glass, which can withstand a heat treatment at 700 ° C. or less, for example, about 600 ° C., which is not expensive, by using a magnetron RF (radio frequency) sputtering method.
A silicon oxide film as No. 1 is formed to a thickness of 1000 to 3000Å. The process conditions were an atmosphere of 100% oxygen, a film forming temperature of 15 ° C., an output of 400 to 800 W, and a pressure of 0.5 Pa. The film formation rate using quartz or single crystal silicon for the target was 30 to 100 Å / min.

A silicon film was formed thereon by LPCVD (Low Pressure Vapor Phase) method, sputtering method or plasma CVD method. When forming by the reduced pressure vapor phase method, it is 1
450-550 ° C, which is low by 00-200 ° C, for example, 530 ° C
CVD of disilane (Si ₂ H ₆ ) or trisilane (Si ₃ H ₈ )
The film was supplied to the apparatus to form a film. The reactor pressure is 30-300
It was Pa. The film forming rate was 50 to 250 Å / min.
Threshold voltage (Vt) between NTFT and PTFT
In order to control the concentration to be substantially the same as that of h), boron may be added during the film formation with diborane at a concentration of 1 × 10 ¹⁵ to 1 × 10 ¹⁸ cm ⁻³ .

When the sputtering method is used, the back pressure before the sputtering is set to 1 × 10 ^-5 Pa or less, the single crystal silicon is used as the target, and the atmosphere is mixed with 20% to 80% of hydrogen in argon. For example, argon is 20% and hydrogen is 80%.
The film forming temperature was 150 ° C., the frequency was 13.56 MHz, the sputter output was 400 to 800 W, and the pressure was 0.5 Pa.

When the silicon film is formed by the plasma CVD method, the temperature is, for example, 300 ° C., and monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is used. These were introduced into a PCVD apparatus, and high-frequency power of 13.56 MHz was applied to form a film.

The film formed by these methods is
It is preferable that oxygen is 5 × 10 ²¹ cm ⁻³ or less. If this oxygen concentration is high, it is difficult to crystallize and the thermal annealing temperature must be high or the thermal annealing time must be long.
If it is too small, the backlight will turn off the light.
The current will increase. Therefore 4 × 10 ¹⁹ to 4 × 10 ²¹
The range was cm ^-3 . Hydrogen is 4 × 10 ²⁰ cm ^-3 and silicon 4
When compared with ^{x10 22} cm ^-3 , it was 1 atom%. Also,
In order to further promote crystallization of the source and drain, the oxygen concentration is 7 × 10 ¹⁹ cm ^-3 or less, preferably 1 × 10 ¹⁹
cm ^-3 or less, and oxygen is ion-implanted into only the channel formation region of the TFT constituting the pixel to form 5 × 10 ^{20 to} 5 × 10 5.
You may add so that it may become ²¹ cm ^-3 . At this time, since the TFTs forming the peripheral circuit are not irradiated with light, it is effective to reduce the mixing of oxygen and have a higher carrier mobility in order to operate at high frequency.

Next, a silicon film in an amorphous state is formed into 500
~ 5,000 Å, for example, 1500 Å after making, 4
Medium temperature heat treatment in a non-oxide atmosphere at a temperature of 50 to 700 ° C. for 12 to 70 hours, for example, 600 in a hydrogen atmosphere.
Hold at a temperature of ° C. Since the amorphous silicon oxide film is formed on the surface of the substrate below the silicon film, no specific nuclei are present in this heat treatment, and the whole is uniformly annealed. That is, it has an amorphous structure at the time of film formation, and hydrogen is simply mixed therein.

The annealing causes the silicon film to shift from an amorphous structure to a highly ordered state, and a part thereof assumes a crystalline state. In particular, a region having a relatively high degree of ordering after the film formation of silicon tends to be crystallized and become a crystalline state. However, since silicon existing between these regions is bonded to each other, the silicon members pull each other. Peak 522 of single crystal silicon as measured by laser Raman spectroscopy
Peaks shifted to lower frequencies than cm ^-1 are observed. The apparent particle size is 50 to 5 when calculated from the full width at half maximum.
Although it is a microcrystal like 00Å, in reality there are many highly crystalline regions with a cluster structure, and each cluster has a semi-amorphous structure in which silicon is bonded (anchoring) with each other. Could be formed.

As a result, the coating is in a state in which it may be said that it is substantially free of grain boundaries (hereinafter referred to as GB). Since the carriers can easily move between the clusters through the anchored portions, the carrier mobility is higher than that of polycrystalline silicon in which so-called GB is clearly present. That is, hole mobility (μh) = 10 to ²⁰⁰ cm ² /
VSec, electron mobility (μe) = 15 to 300 cm ² / V
Sec is obtained.

On the other hand, when the film is polycrystallized by a high temperature anneal of 900 to 1200 ° C. instead of the anneal at the medium temperature as described above, the solid phase growth from the nuclei causes the segregation of impurities in the film. , GB have a large amount of impurities such as oxygen, carbon, and nitrogen, and have a large mobility in the crystal, but they form a barrier in GB and hinder the movement of carriers there. As a result, it is difficult to obtain a mobility of 10 cm ² / Vsec or more. That is, in this embodiment, the silicon semiconductor having the semi-amorphous or semi-crystal structure is used for the reason as described above.

A silicon oxide film was formed thereon as a gate insulating film to a thickness of 500 to 2000Å, for example 1000Å. This was performed under the same conditions as the production of the silicon oxide film as the blocking layer. During this film formation, a small amount of fluorine may be added to immobilize sodium ions.

After this, 1-5 × 10 ²¹ cm of phosphorus is placed on the upper side.
^-3 concentration silicon film or this silicon film with molybdenum (Mo), tungsten (W), MoSi ₂ or
A multilayer film with WSi ₂ was formed. This was patterned with a second photomask to obtain FIG. 7 (B). A gate electrode 9 for PTFT and a gate electrode 19 for NTFT were formed. For example, the channel length is 10 μm, the gate electrode is 0.2 μm of phosphorus-doped silicon, and 0.3 molybdenum is formed thereon.
It was formed to a thickness of μm. In FIG. 7C, a photoresist 57 is formed using a photomask, and PTF is used.
1 to 1 of boron is added to the source 10 and the drain 12 for T.
A dose amount of 5 × 10 ¹⁵ cm ⁻² was added by the ion implantation method. Next, as shown in FIG. 7D, an NTFT was formed using a photomask. A source 20 for the NTFT and phosphorus as a drain 18 were added by an ion implantation method at a dose amount of 1 to 5 × 10 ¹⁵ cm ^-2 .

These are performed through the gate insulating film 54. However, in FIG. 7B, the silicon oxide on the silicon film may be removed using the gate electrodes 9 and 19 as a mask, and then boron and phosphorus may be directly ion-implanted into the silicon film.

Next, heating anneal was performed again at 600 ° C. for 10 to 50 hours. The source 10 and drain 12 of the PTFT, the source 20 and the drain 18 of the NTFT were produced as P ⁺ and N ⁺ by activating impurities. Channel forming regions 21 and 11 are formed below the gate electrodes 9 and 19 as semi-amorphous semiconductors.

In this way, a C / TFT can be manufactured without applying a temperature above 700 ° C. in all steps, even though it is a self-aligned method. Therefore, it is not necessary to use an expensive substrate such as quartz as the substrate material, and the process is very suitable for the large-pixel liquid crystal display device of the present invention.

In this embodiment, the thermal anneal is shown in FIG.
Done twice in (D). However, the anneal shown in FIG. 7A may be omitted depending on the desired characteristics, and both may be combined with the anneal shown in FIG. 7D to reduce the manufacturing time. In FIG. 7E, an interlayer insulator 65 was formed as a silicon oxide film by the above-described sputtering method. The silicon oxide film may be formed by using the LPCVD method, the photo CVD method, or the atmospheric pressure CVD method. For example, it is formed to have a thickness of 0.2 to 0.6 μm, and then a window 66 for an electrode is formed using a photomask. Further, aluminum is formed on all of them by a sputtering method to form leads 71, 72 and contacts 67,
After forming 68 using a photomask, an organic resin 69 for flattening the surface, for example, a translucent polyimide resin was applied and formed, and electrode holes were formed again using the photomask.

As shown in FIG. 7F, two TFTs have a complementary structure, and the output terminal thereof is connected to the electrode of one pixel of the liquid crystal device as a transparent electrode. Therefore, ITO (indium) is formed by a sputtering method. -Tin oxide film) was formed. It was etched with a photomask to form the pixel electrode 17. This ITO was formed into a film at room temperature to 150 ° C. and accomplished by oxygen at 200 to 400 ° C. or an anneal in the atmosphere.

In this way, the PTFT 22 and the NTFT are
13 and the transparent conductive film electrode 17 which is a pixel electrode were formed on the same glass substrate 50. The characteristics of the obtained TFT are P
The TFT has a mobility of 20 (cm ² / Vs) and a Vth of -5.9.
At (V), the mobility was 40 (cm ² / Vs) in NTFT and Vth was 5.0 (V).

It goes without saying that the above manufacturing method is exactly the same for the buffer type and the inverter type.

A liquid crystal cell was formed by bonding one substrate for a liquid crystal device manufactured according to the above method and the other substrate having a transparent electrode on the entire surface of a glass substrate. A ferroelectric liquid crystal composition was encapsulated in it. In FIG.
The PTFT 13 is provided at the intersection of the first scanning line 5 and the data line 3, and the PTFTs for other pixels are similarly provided at the intersection of the first scanning line 5 and the data line 4. Meanwhile NT
The FT is provided at the intersection of the second scanning line 8 and the data line 3. Further, an NTFT for another pixel is provided at the intersection of another adjacent first scanning line 6 and data line 3. A matrix structure using such C / TFTs (in this case, an inverter type) is provided. PTFT1
3 is connected to the first scanning line 5 via the contact 69 at the input end of the drain 10, and the gate 9 is connected to the data line 3 in which the multilayer wiring is formed. The output end of the source 12 is connected to the pixel electrode 17 via a contact 67.

On the other hand, in the NTFT 22, the input end of the drain 20 is connected to the second scanning line 8 via a contact, the gate 21 is connected to the data line 3, and the output end of the drain 18 is connected via the contact 68 in the same manner as PTFT. It is connected to the pixel electrode 17. Thus, the pixel 17 made of the transparent conductive film and the PTFT 1 are sandwiched between the pair of scanning lines 5 and 8 (inside).
3 and C / TFT composed of the NTFT 22 constitute one pixel. By repeating this structure horizontally and vertically, a 2 × 2 matrix is enlarged to 64.
A liquid crystal display device with large pixels such as 0x480 and 1280x960 can be used.

The feature here is that two TFs are provided for one pixel.
By providing T in a complementary configuration, the pixel electrode 17 is fixed to the liquid crystal potential V _LC of three values.

FIG. 6 shows an example of the drive signal applicable to this embodiment. FIG. 6 shows an example of the drive signal in the 4 × 4 state. X _1a X _1b , X _2a X _2b , X _3a X _{3b in FIG} .
X _4a X _4b function as a pair of scanning signal lines in the X direction. Further, Y ₁ , Y ₂ , Y ₃ , and Y ₄ function as data lines in the Y direction. Also, AA, AB ... D in the figure
D means the address of the pixel at the corresponding position. In FIG. 4, P, N, PTFT and NTFT are shown in the figure.
However, it is needless to say that if the PTFT and the NTFT are replaced with each other, it becomes a buffer type.

In the present embodiment, when one screen is displayed by applying drive signals of a plurality of frames to the liquid crystal for one display screen, the number of selection signals applied to specific pixels should be reduced from the total number of frames. Thus, gradation display can be easily performed.

In the present invention, an organic film is used as the alignment film, and the operating voltage is ± 20 to ± 25 V and the cell interval is thinned to 1 to 3 μm in order to increase the switching speed.

Further, as the semiconductor of the TFT used in this embodiment, materials other than those used in this embodiment can be used.

FIG. 8 shows a sectional structure of the second liquid crystal device of the present invention.
It was shown to. First, a 1.1 mm thick soda-lime glass substrate (40
1) on top, using DC sputtering method, 1200 Å IT
An O (indium tin oxide) thin film (402) was formed. Then, a photolithography method was used to provide electrodes and leads to form a first substrate (408). Similarly, electrodes and leads (404) are provided, and polyimide is printed on the electrodes by the offset method to a thickness of 800 Å, and the electrodes are printed at 380 ° C for 3
After baking for 0 minutes, a means (405) for rubbing the surface in a certain direction with a long-haired cloth to cause the liquid crystal composition to be aligned at least in the initial stage was provided as a second substrate (409).

An epoxy adhesive (407) was printed around the first substrate by screen printing, and a silica sphere (406) having a diameter of 4.2 μm was spun on the second substrate by 1 mm. After spraying at a ratio of 200 per ² parts, the first substrate and the second substrate were attached to each other to obtain a second device.

Next, the driving method will be described with reference to FIGS. 8 and 9.

Colors to be displayed in the pixels A1 (301) to B2 (304) are respectively set to the pixels A1 (R0, G0, B1),
Pixel A2 (R1, G1, B1), Pixel B1 (R0, G
1, B1) and the pixel B2 (R1, G0, B1), the first period (40
In 1), the pixel A1 (301) of the first device is turned off (non-transmissive state), the pixel A2 is turned on (transmissive state) in the same manner in the other second and third periods. Two screens are constructed.

Color display is possible in this way, and
The colors are displayed. Further, when eight gradations were performed by the first device, 512 colors could be displayed.

[0047]

As described above, according to the structure of the present invention, as compared with the conventional television receiver using the cathode ray tube,
The weight can be reduced by about 70%. By using the present invention, it is difficult to improve the yield in the conventional active matrix type display device. Furthermore, the yield which is close to 0 by using three of them is to use one display device or another type of display device. It was also possible, and a dramatic improvement was seen.

[Brief description of drawings]

FIG. 1 shows a structure of a television receiver of the present invention.

FIG. 2 shows a structure of a conventional liquid crystal projection type television receiver.

FIG. 3 is a circuit diagram of a conventional active matrix liquid crystal device.

FIG. 4 shows a circuit diagram of this embodiment.

FIG. 5 shows a basic structural diagram of this embodiment.

FIG. 6 shows drive signals of the present embodiment.

FIG. 7 shows a process of this example.

FIG. 8 shows the structure of the present embodiment.

FIG. 9 shows a pixel configuration of this embodiment.

FIG. 10 is a structural diagram of a CRT projection television.

FIG. 11 shows a driving method of the present embodiment.

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[Procedure amendment]

[Submission date] December 26, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (2)

[Claims] 1. A color display is performed by temporally changing the color of light on an optical path formed by one or more first liquid crystal devices for displaying television images, a light source of the device, and a projection place. In a television receiver, an optical shutter comprising three or more sheets is used as a means for changing the color of light with time. 2. A television receiver according to claim 1, wherein a liquid crystal composition exhibiting ferroelectricity is used as an optical shutter comprising three or more sheets as means for temporally changing the color of light.