JPS5981627A - Optical writing type liquid crystal light bulb element - Google Patents

Abstract

PURPOSE:To obtain titled element which has a fast optical response speed and good characteristic reproducibility and is manufactured easily by making a photoconductor layer of a specific amorphous silicon film, and forming a light shielding film of a specific amorphous silicon film which contains fluorine and hydrogen. CONSTITUTION:A transparent conductive film 15, a photoconductor film 16, a light shielding film 17, and a dielectric multi-layered reflecting film 18 are laminated on the 1st glass base board 14 and liquid crystal 20 is sealed between the 1st glass base board and the 2nd glass base board 23 with the 2nd transparent conductive film 22 to constitute an optical writing type liquid crystal light bulb element. The photoconductor film 16 is made of an a-Si:H film which is formed by glow discharge at 300 deg.C base board temperature under 0.3Torr pressure while using SiH4 as raw material gas and has <=10<-7>OMEGA<-1>cm<-1> dark conductivity and about 10<-4>OMEGA<-1>cm<-1> bright conductivity and the light shielding film 17 is made of an a-Si:F:H film formed successively by glow discharge at a 10 gas mixing ratio SiF4/H2 of SiF4 and H2, at 300 deg.C base board temperature, and under 1Torr pressure without leaking a sample from a forming device.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical writing type liquid crystal light valve element used in a projection type large screen display device or the like.

Optical writing type liquid crystal light valve elements are used in projection type large screen display devices and input/output devices in optical image processing, such as incoherent-coherent light image conversion elements, and are used to convert optical input information into optical output information. It is a key device. An optical writing type liquid crystal light valve generally has a structure as shown in FIG.
, a light shielding film 4 for separating input light 12 and output light 13;
It has a structure in which a dielectric multilayer reflective film 5 is provided, and a display layer 8 made of liquid crystal is sandwiched between glass substrates 6 on which a fourth transparent conductive film 7 is attached. Here, 9.9' is an alignment treatment layer made of an insulating film for aligning liquid crystal molecules, lO is a spacer,
11 is a power supply.The properties required for each part in this structure are as follows. First, the optical writing layer 3 made of a photoconductor has a dark conductivity of 10"Ω-1cm" or less and an attractive conductivity of 10' to 10'.
Ω″″1tYn− or more, then the uniform plume layer 4 has an attractive conductivity of 1
The absorption coefficient is large at less than 0Ω-1crB I.The transmittance of the multi-electrode reflective film is less than 10Ω. - The conductivity of the leading conductor is a value necessary to obtain high resolution and high contrast.

Also, the light shielding film is essentially required if the transmittance of the dielectric multilayer reflective film is zero.7. Regarding the i' part, in order to obtain such a reflective film, strict film thickness control on the order of angstroms is required, and such control is practically impossible. Conductivity 10-
A light absorbing material having a resistance of 7Ω"σ- or less can obtain a light shielding ability of 10" to 10"@.

Conventionally, CdTe has been used for CdS photoconductors as a material that satisfies the above conditions, and silicon crystal photoconductors 1
On the other hand, a thin film such as cermet, which contains a large amount of metal such as nickel or zinc in silicon dioxide, has been used as a light blocking and collecting material. However, these materials are different from each other, and their manufacturing methods are different, and they tend to cause mismatching of lattice constants between the light 4 body, the Ryukyu layer, and the electrified multilayer reflective film. Furthermore, since the response speed of CdS photoconductors is long, ranging from several milliseconds to several tens of milliseconds, the biting means is used for writing slide images, and for the relatively long length of CdS photoconductors.
It is limited to writing by RT, and is not suitable for high-speed scanning recording such as laser scanning recording, in which pixel writing takes several microseconds or more. Due to these several drawbacks, the structure of the liquid crystal light valve becomes complicated, resulting in an expensive device, and the use of the liquid crystal light valve is limited.The purpose of the present invention is to The object of the present invention is to eliminate the drawbacks of the optically embedded type liquid crystal light valve element (1), and to provide an optically embedded type liquid crystal light valve element that has a high yC conversion speed, is easy to manufacture, and has good reproducibility of characteristics. The optically writable liquid crystal light valve element of the present invention is different from the conventional Mitsutoyokomiya liquid crystal light valve element, in which the photoconductor film portion has a dark conductivity of 102 Ω-1 m-1 or less and a light S conductivity of 10.
It is composed of an amorphous silicon film (a-8i:H) with a property of -6 to 10"Ω"6n" or more, and the light-transmitting film part is made of fluorine with a conductivity of 10"Ω"cnT" or less. The invention is characterized by being composed of an amorphous silicon film (a-3i:, F':)i) containing hydrogen. Since it was shown that the valence electrons of amorphous silicon can be controlled by erasing ring bonds, various applications of amorphous silicon have been actively researched. Due to its high dark resistance and photosensitivity, it has been considered to be applied to optically written liquid crystal light valve elements, but so far none has been put into practical use.The biggest reason for this is:
A light-shielding film material such as CdTe for CdS has not been found for amorphous silicon.The characteristics required for an oJ optical film are 10-7Ω-2 when exposed to projection light.
It has a conductivity of 1 or more than ctn-+, and a high absorption coefficient of IQ"ff1- or more over the entire visible region.The former is the voltage applied to the liquid crystal because it ensures h1-2. A film that satisfies the requirements of high resistance, very small photosensitivity, and high absorption, which are the characteristics necessary to obtain a large 0N-OFF ratio, and that can be stably stacked on amorphous silicon. This is why optically written liquid crystal light valves using amorphous silicon were not put into practical use.Meanwhile, research into using fluorine as a dunking bond terminator for amorphous silicon was actively conducted. ing.

This is because the bond energy between silicon and fluorine is greater than the bond energy between hydrogen and silicon, and there is a possibility that a thermally stable film can be obtained.

In our research, we discovered that films containing fluorine and hydrogen have a larger scissor-like coefficient than films containing hydrogen. Furthermore, we believe that this film containing fluorine and hydrogen has a large absorption required for the light-shielding film, has high resistance, has a small increase in conductivity, and is a good match with an amorphous silicon film that only contains hydrogen. We have found that this satisfies the conditions and have applied this to a liquid crystal light valve element. First, the a-8i:H film used as a photoconductor film will be explained while showing its characteristics. 3 (Figure 2 shows the claw discharge method I
σ0. is the dark conductivity, and σ is the bright conductivity when irradiated with AMI (100rr!V10A light with the same spectrum as sunlight). As is clear from the figure, the conductivity increases as the substrate temperature of film formation n, 4 rises to 300°C.
It is saturated at higher temperatures than all. Moreover, at temperatures above 200°C, the dark conductivity is 10-701 C or less, which is necessary for the photoconductor film of a photo-impregnated liquid crystal light valve element, and the bright conductivity is 4-4! ,OT'
It can be seen that the value of ~10-40-'m'' is fully satisfied.

By the way, when the substrate temperature is below 130℃, the bright conductivity is lO''
Ω1c1n'' or less, and it seems that this film can be used as a light-shielding film, but it is known that films formed at low temperatures are generally thermally unstable due to the tendency for hydrogen to escape, making them unsuitable for practical use.

Next, amorphous silicon containing fluorophore δ water satisfies the conditions as a light-shielding film under certain growth conditions, and if the conditions are changed, it can also be used as a photoconductor film, so the photoconductor film and light-shielding film are continuous. Figure 3 shows that amorphous silicon can be grown and a practical liquid crystal light valve element can be obtained using amorphous silicon. amorphous silicon (a
-8+ m f' :H) s' of rate σ8iFa and H
a Mixing ratio dependence is shown. In the figure, σD is dark conductivity, σP is AMI (the spectrum is almost the same as that of sunlight, and 1
It shows the bright conductivity when irradiated with light with an energy density of 00rnW/-. Also, the substrate temperature during growth is approximately 320℃.
℃ pressure is about I Torr.

As is clear from the figure, when the mixture ratio 5iF-/H- is 30 or more, the conductivity IM rate is less than lOΩ crn, and it can be seen that the conductivity satisfies the conditions for a light-shielding film.

Furthermore, when 8 i Fa / H* is around 10, the contrast ratio of conductivity is nearly 6 digits -ft, indicating that it can be used satisfactorily as a four-electrode film. FIG. 4 shows the dependence of conductivity on substrate temperature and pressure. From the figure, it can be seen that a high substrate temperature of 380° C. or higher is better for the photoconductive film. In addition, it can be seen that the conductivity at low temperatures decreases, making it suitable for light-shielding films.It is better to control the temperature in order to make a good film like this, but film formation is difficult with photoconductor films and light-shielding films. Because they are carried out in this order, the temperature will be lower in the latter order, and there will be no adverse effect on the characteristics of each.

FIG. 5 shows the dependence of the absorption coefficient α on 8 f Fa /Hm.

Figure I is important. :! It can be seen that the larger S i F a /Ht is, the larger the absorption coefficient is, and when s S + F 4/11 is about 30, it sufficiently satisfies the conditions necessary for a light-shielding film. Therefore, in the glow discharge method, the substrate temperature
The light shielding film can be obtained at a temperature of 20° C. or lower, a gas mixture ratio of about 30, and a pressure of ITorr.

In this way, the optical Sogogoya liquid crystal light valve element of the present invention can achieve C
Conventionally, Cd8 was used as a light guide film, and C was used as a light shielding film.
dTe was used, but the present invention is characterized in that a-8e:H is used for the photoconductor film, and a-8i:F:H is used for the light-shielding film, both of which are amorphous silicon. The device has the following advantages over conventional devices, such as improved characteristics and ease of manufacture.

1) a-8i:H has a light response speed that is at least one order of magnitude faster than Cd8, and a high-speed response optical writing ID liquid crystal light valve element can be obtained. 2) Materially, a8s*H and α- 8i:F:H is a very similar material and does not have instability such as peeling phenomenon due to lattice mismatching.

3) allows continuous growth at almost the same temperature, greatly shortening the formation time and saving power.

4) Because of continuous growth, the interface between the photoconductor film and the light-shielding film can be kept clean, and there is no deterioration of characteristics due to individual interfaces.

5) Cd8. While CdTe is a hazardous substance, Maro-8i is a non-polluting material.

Next, an embodiment of the present invention is shown in FIG.

In the figure, 14.23 is a glass substrate, i5.22 is an I
TO transparent electrode, 16, was prepared by a glow discharge method using 81 Ha as a raw material gas at a substrate temperature of 300° C. and a pressure of 0.3 Torr, with a dark conductivity of 10 GoΩ-1ff11 or less and an attractive conductivity of IO″Ω-1Crn’- 1 degree a S+:I
I film, 17 is 8iFa and Ha dregs mixing ratio S i F4
/ ) (x is 10. A S r :F : Ha was formed continuously by the claw discharge method without taking out the sample from the forming apparatus under the conditions of a substrate temperature of 300 degrees Celsius and a pressure of 1 Torr,
The electrical conductivity of this part is less than IOΩ. 18 is a transparent, body multilayer reflective film made by laminating cerium oxide and magnesium fluoride with a reflectance of 90 inches or more, and 19.19' is a liquid crystal molecular axis made by obliquely depositing SiO and water-battered on the substrate. In order to use twisted nematic mode liquid crystal, these layers are arranged so that the viewing direction of the obliquely evaporated evaporated materials is opposite to each other. .Therefore, this alignment treatment layer provides 450
It gives the LCD a twist. The addition is E for the display liquid crystal.
4-cyano-4'-n-penterbiphenyl, 4-cyano-4'-n-heptylbiphenyl, 4-cyano-4/n-ocmexybiphenyl, and 4·-cyano-4/-n-pentyl 7 Terphenyl, respectively, is 0.2
5.0.51.0. It is a mixed product mixed in the ratio of L014, and is a liquid crystal that operates in V-field effect type twist, immature, and couple mode.
K-Zo.

25 is a writing light, and 26 is a projection light.

The optical writing type liquid crystal light valve element obtained by the above I is as follows:
It can fully follow laser light with a pulse width of lμ5eca,
I was able to confirm its high speed. Moreover, as described above, the photoconductor film and the light shielding film are obtained by continuous formation.

As explained above, the optically writable liquid crystal light valve cluster of the present invention has a Si:H or i;J;I-Si:
F:H to photoconductor film, a 8 r a 1”:
By using H as a light-shielding film, elements can be easily formed using stable and non-polluting materials, and high-speed devices can be obtained, which have many industrial advantages. ◇

[Brief explanation of drawings]

Fig. 1 is a 1rPt diagram of a general conventional nine-layer liquid crystal light valve element, Fig. 2 is a diagram showing the substrate temperature dependence of the conductivity of an a-8i:H film, and Fig. 3 is an a- 8i:F:H(7
) $ Electricity rate (D Car X Mixing ratio S i F a / H
A diagram showing the dependence, H744 diagram is a-sl: F:
A diagram showing the substrate temperature dependence of conductivity in the I-1 film,
Fig. 5 is a diagram showing the change in absorption g-m of a-8i:F:11 due to a waste mixture ratio of 8iFt/H, and Fig. t36 is a diagram showing a change in absorption g-m of a-8i:F:11 due to a waste mixture ratio of 8iFt/H. It is a figure which shows an example. In the figure, 1.6...Glass, ■Plate, 2.7...
...Transparent electrode, 3...Photoconductor film, 4...
... light shielding film, 5 ... rust electric multilayer reflection)
8...LCD, 9.9'...
...Orientation treatment layer, 10... Spacer, II.
...Power supply, 12...Integrated light, 13...
...Projection light, 14. λ3...Glass substrate,
15+22...ITO electrode, 16...
aSs for photoconductor: F: Ha, 17...
...For release light a=Si:B°: ■1 film, 18...
・・Visiting body multilayer reflective film, 19.19'・---Si
O alignment treatment layer, 20...Liquid crystal (E7), 21.
...Spacer, 2A...AC power supply, 5
...Writing light, 26...Projection light. Oli￥1 Ai 2 Figure 5IF4/H2 Figure 3

Claims (1)

[Claims] 1. On the first glass substrate, a transparent conductive film, a photoconductor film,
In an i-optical writing type liquid crystal light valve element having a structure in which a light shielding film and a dielectric multilayer reflective film are laminated and a liquid crystal is sealed between the glass substrate having a second transparent conductive film, the photoconductor film is The dark conductivity is less than 1o''Ω''i, and the bright conductivity is lO''~1
The light-shielding film is composed of an amorphous silicon film having a property of 0-4Ω-1Lyn" or more, and the light-shielding film is an amorphous silicon film containing fluorine and hydroxide having a bright conductivity of 10'Ω-'Cn1" or less. An optical writing type liquid crystal light valve element characterized by being composed of a silicon film. 2. The optically writable liquid crystal light valve element according to claim 1, wherein the amorphous silicon film constituting the photoconductor film is an amorphous silicon film containing hydrogen. Claim 1, wherein the amorphous silicon film constituting the photoconductor film is an amorphous silicon film containing fluorine and hydrogen.
Optical writing type liquid crystal light valve element described in Section 1': fO