JP2871834B2 - Electron beam writing type transmission type spatial light modulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electron beam writing type spatial light modulator,
More specifically, the present invention relates to an electron beam writing type transmission type spatial light modulator having a function of inputting image information and data information to a spatial light modulator using an electron beam and displaying the information two-dimensionally using display light. .

SUMMARY OF THE INVENTION The present invention provides an electron beam writing type transmissive spatial light having a function of inputting image information and data information to a target using an electron beam and displaying the information two-dimensionally using display light. Regarding the modulation tube, in particular, a nematic liquid crystal, a cholesteric liquid crystal or a smectic liquid crystal and any one of an ordinary refractive index, an extraordinary refractive index of the liquid crystal, and a refractive index when the liquid crystal is randomly aligned, between the transparent dielectric layer and the transparent electrode. A structure in which the liquid crystal is confined in a transparent resin matrix having the same refractive index as the above, or a liquid crystal composite having a structure in which the resin matrix is dispersed and confined in the liquid crystal, is formed on the transparent dielectric layer and the transparent electrode. Generates electrons, forms, accelerates, and focuses an electron beam with a target inserted in close contact, and controls the electron beam intensity according to the input signal. An electron gun comprising a cathode and one or more grids, a vacuum vessel containing a secondary electron collecting electrode (collector) for controlling the charge on the target surface, and an electron beam deflection system for deflecting the electron beam Since the electron beam writing type transmission spatial light modulator is used, a bright display image is obtained without the need for a polarizing plate, and the display image has excellent spatial uniformity, fast response, and high contrast. This makes it possible to obtain such an effect that the display of an analog image becomes easy.

[Prior Art] Conventionally, devices disclosed in the following documents are known as electron beam writing type spatial light modulators.

(1) Reference 1 (G. Marie: Ferroelectrics Vol. 10, (197
6) On P.9 to P.14), as shown in FIG. 7, the CaF ₂ holder 34, the transparent electrode 20, the KD ₂ PO ₄ 33, and the dielectric mirror 22 ′ are closely adhered in the vacuum vessel 11 in order. Target 79 and Peltier device
35, an electron beam writing type spatial light modulator having a structure in which a cathode 35, a cathode 2, a main grid 10 'and a sub grid 10 "are enclosed. In the drawing, reference numerals 36 and 36' denote signal input leads, 26 is a light source, 28 is a lens, 38 is a polarizing prism,
16 is incident light, 17 is display light, and 15 is an electron beam.

In the above configuration, the constant current electron beam emitted from the cathode collides with the dielectric mirror, and forms a charge pattern on the surface of the dielectric mirror in accordance with a signal applied between the main grid and the transparent electrode. This charge pattern is KD ₂ P
Due to the electro-optic effect of the O ₄ crystal, it is converted into a spatial change in the refractive index. On the other hand, the incident light 16 emitted from the light source 26 is
The light is polarized by the polarizing beam splitter 38, passes through the lens 28, passes through the CaF ₂ holder 34 in the vacuum vessel 11, the transparent electrode 20, and the KD ₂ P
The light is reflected by the dielectric mirror 22 ′ through the O ₄ crystal, follows the above-described optical path in the reverse direction, and is projected as display light on the screen (not shown) through the polarization beam splitter 38.

(2) Reference 2 (K. Shinoda and Y. Suzuki: Proc. SPIE (19
86) On pages 613 to 619), as shown in FIG. 8, a MgO thin film 40, a dielectric mirror 22 ', and a LiNbO ₃ crystal
41, a target 89 to which the transparent electrode 20 adheres sequentially, and a phase compensator 4 to which the transparent electrode 20, LiNbO ₃ 41, and the transparent electrode 20 adhere sequentially
2, an electron beam writing type spatial light modulator tube enclosing a cathode 2, a frid 42, 43, 44, 45, 46, 47 and a mesh electrode (collector) 48 is shown. In the same figure, 18
Is a beam splitter, 49 is a polarizing plate, 28 is a lens, 26 is a light source, 30 is a screen, 16 is incident light, 17 is display light, and 15 is an electron beam.

In the above configuration, the constant current electron beam 15 emitted from the cathode 2 is applied to the grids 42 to 47 and the mesh electrode.
It strikes the MgO thin film 40 through 48. By controlling the electron beam current by applying an electric signal to the grid 42, a charge pattern is formed on the surface of the MgO thin film. This charge pattern is converted into a spatial change in the refractive index by the electro-optic effect of the LiNbO ₃ crystal.

On the other hand, the incident light 16 from the light source 26 is
Through the beam splitter 18, the phase compensator 42 and the target 89 in the vacuum chamber 11, and the dielectric mirror 2
The beam splitter 1 reflects at 2 'and follows the reverse optical path.
8, images and patterns are projected on the screen 30 through the lens 28 and the polarizing plate 49.

(3) Reference 3 (DAHaven: IEEE Transactions on Elect
ron Devices Vol. ED-30, (1983) P.498-P.492), as shown in FIG.
99, a writing electron gun 1 'and an erasing electron gun 1 "are enclosed. In the same figure, 26 is a light source, 28 is a lens, 49 is a polarizing plate, 15' is a writing electron beam, and 15" is a writing electron beam. An erasing electron beam, 16 is incident light, and 17 is display light. As shown in FIG. 10, the target 99 includes a face plate 11 ′ of a vacuum vessel, a transparent electrode 20, a twisted nematic liquid crystal 52,
It is composed of a spacer 53 and a thin dielectric plate. In the figure, reference numeral 55 denotes a secondary electron collecting electrode (collector).
Although not shown in the figure, an alignment layer is required between the transparent electrode 20 and the dielectric thin plate 54 and the liquid crystal 52 in order to align the twisted nematic liquid crystal.

In the above configuration, if an electric signal is applied to a grid (not shown) to control the intensity of the electron beam emitted from the writing electron gun, a charge pattern corresponding to the input signal can be formed on the surface of the dielectric thin plate 54. Can be. At this time, the liquid crystal molecules in the target 99 are arranged according to this charge pattern, and the spatially uniform incident light emitted from the light source 26 is
The light passes through the polarizing plate 49, the target 99, and the polarizing plate 49, and is converted into a grayscale image according to the input signal.

(4) Reference 4 (TTTrue: SID '87 International Sympo
sium (1987) P.68-P.71), as shown in FIG.
In a vacuum vessel 11, a target 109 made of a glass disk whose one surface is conductively treated, a transparent oil 57, an input mask 58, and the electron gun 1 are sealed. In the figure, 26 is a light source, 25 is a total reflection mirror, 59 is a dichroic filter, 28 is a lens,
16 is incident light, and 17 is display light.

In the above configuration, the white incident light 16 from the light source is separated by the dichroic filter 59 into blue and red light beams as shown in FIG. 11 (a). In the central part and the peripheral part of the input mask 58 and the output mask 60, the directions of the slits are perpendicular to each other as shown in FIGS. 11B and 11C, so that the blue light flux and the red light flux are independent of each other. Schlieren optical system. Target 109 is sump 57 '
Rotate slowly while immersing in the transparent oil 57 inside to form a smooth oil film layer on the glass surface of the target. Electron beam
If 15 does not enter this oil film layer, the oil film layer surface is smooth and the blue and red light fluxes are blocked by the output mask and do not reach the screen. On the other hand, when the electron beam collides with the oil film layer, the surface of the oil film layer is charged, and the oil film layer is distorted by electrostatic force. At this time, the light beam is diffracted by the oil film layer and reaches the screen through the gap between the output masks.

[Problems to be solved by the invention] However, the above-mentioned conventional electron beam writing type spatial light modulator has a problem to be solved as described below.

(I) In the spatial light modulator of the document 1 shown in FIG. 7 of item (1) or the spatial light modulator of document 2 shown in FIG. 8 of item (2) described as the prior art, KD ₂ PO ₄ Crystal 33 or LiNb
Since the electro-optic effect of the O ₃ crystal 41 is used, a polarizing beam splitter 38 or a polarizing plate 49 is required. Therefore, when the incident light 16 is non-polarized light, the light propagation loss becomes 50% or more.

Since it is necessary to make the thickness of the KD ₂ PO ₄ crystal 33 or the KiNbO ₃ crystal 41 uniform, an advanced crystal processing technique is required and the cost is high.

When the spectrum width of the incident light 16 is wide, the contrast of the output image decreases.

High parallelism of incident light 16 is required. To do this,
It is necessary to make the light emitting portion of the light source 26 dot-shaped, and the brightness of the display light is also reduced.

The resolution improves when the KD ₂ PO ₄ crystal 33 or the LiNbO ₃ crystal 34 is thinned, but there is a limit (at present about 100 μm) in thinning the bulk crystal by polishing, and it is difficult to achieve high resolution.

It is technically and economically difficult to obtain a large-area KD ₂ PO ₄ crystal 33 or LiNbO ₃ crystal 41.

Due to the drawbacks described above, it is difficult to display a highly accurate image or pattern.

The driving voltage is large.

There are drawbacks such as. Further, in the spatial light modulation tube of the document 1 shown in FIG. 7 of the item (1) described as the prior art, it is necessary to cool the KD ₂ PO ₄ crystal 33 to about −50 ° C. using the Peltier element 35, This complicates the device configuration.

 There is also a problem.

(II) FIG. 9 and FIG.
In the spatial light modulator of Reference 3 shown in FIG. 10, since the twisted nematic liquid crystal 52 is used, the polarizing plate 49 is required, and the light propagation loss is 50% or more.

Response is slow.

It requires an alignment layer to align liquid crystal molecules in advance,
This complicates the production process.

There are drawbacks such as. Therefore, the spatial light modulator of Document 3 is not suitable for displaying a bright moving image.

(III) In the spatial light modulation tube of Document 4 shown in FIG. 11 of (4) described as the prior art, since the transparent oil 57 is used, oil vapor is generated by the collision of the electron beam with the oil film layer. Then, the cathode filament is deteriorated. Further, the degree of vacuum of the vacuum container is reduced.

A warm-up time of several tens of minutes is required because the oil is heated and used.

In order to use the diffraction light in the oil film layer as display light,
In order to reduce the loss of display light, a large schlieren optical system is required.

Since it requires a high-precision and large schlieren optical system, it is extremely expensive.

There are drawbacks such as. Therefore, the spatial light modulation tube of Document 4
It cannot be a compact and inexpensive image display device.

 There are drawbacks.

Therefore, an object of the present invention is to solve the above-described various problems, to perform high-quality and bright image and data pattern display at high speed, and to display a high-definition moving image on a large screen. Another object of the present invention is to provide a compact electron beam writing type spatial light modulator suitable for image processing.

[Means for Solving the Problems] To achieve the above object, the present invention provides a liquid crystal display device comprising a nematic liquid crystal, a cholesteric liquid crystal, or a smectic liquid crystal between a transparent dielectric layer and a transparent electrode; A configuration in which the liquid crystal is dispersed and confined in a transparent resin matrix having a refractive index equivalent to either the refractive index or the refractive index when the liquid crystal is randomly oriented, or the resin matrix is dispersed in the liquid crystal. A liquid crystal composite of a confined configuration is inserted into the transparent dielectric layer and the transparent electrode so as to be in close contact with the transparent dielectric layer. The target generates electrons, forms, accelerates, and focuses an electron beam, and responds to an input signal. A cathode for controlling the intensity and one or more electron guns comprising one or more grids,
A vacuum vessel containing a secondary electron collecting electrode (collector) for controlling the charge on the surface of the transparent dielectric layer, and a spatial light modulation tube using an electron beam deflection system for deflecting the electron beam. Features.

Further, the first embodiment of the present invention is characterized by having a target in which a face plate of a vacuum vessel, a transparent electrode, a liquid crystal composite, and a transparent dielectric layer are sequentially adhered.

In the second embodiment of the present invention, the secondary electron emission ratio δ (the number of electrons incident on the target surface is n ₁ ,
Assuming that the number of emitted electrons is n ₂ , a characteristic feature is that a material (for example, an MgO thin film) having a large value of δ = n ₂ / n ₁ is attached.

Further, the third embodiment of the present invention is characterized in that the optical system has an aperture for transmitting non-scattered light and blocking scattered light or an aperture for performing the reverse operation.

Further, the fourth aspect of the present invention is characterized in that the target is simultaneously scanned with a certain time difference between the erasing electron beam and the writing electron beam.

[Operation] Since the present invention is configured as described above, it is possible to display a high-quality and bright image or a data pattern at a high speed, is suitable for displaying high-definition moving images, and has a large screen. Becomes possible.

(1) That is, since the spatial light modulator according to the present invention utilizes the light scattering characteristics by applying a voltage to the liquid crystal composite, an image is displayed without using a polarizing prism or a polarizing plate having a function equivalent thereto. be able to. For this reason, the present invention can display an image or pattern which is bright, has high contrast and is excellent in spatial uniformity, and has a large light propagation loss peculiar to the conventional spatial light modulator described in the above (I). The problems such as the need for advanced crystal processing technology, the decrease in contrast, the need for high parallelism in display light, the large drive voltage, etc., and the conventional spatial light described in the above (II). Problems such as a point that light propagation loss is large, a response is slow, and a liquid crystal alignment layer is required, which is peculiar to the modulation tube, and an oil that is peculiar to the conventional spatial light modulation tube described in the above (III). There are no problems such as device deterioration due to steam, long start-up time, large schlieren optical system, and extremely high cost.

(2) Furthermore, while the conventional spatial light modulator using liquid crystal must strictly control the thickness of the liquid crystal layer (for example, the thickness error is 1/10 or less of the incident wavelength), In the spatial light modulator, the thickness variation of the liquid crystal composite is allowed up to several times the incident wavelength, so that it can be much larger than conventional spatial light modulators, and the device can be easily manufactured. is there.

(3) Further, the light transmittance versus applied voltage characteristic of the liquid crystal composite constituting the present invention has a smaller γ characteristic (a change amount of the light transmittance with respect to a small change amount of the applied voltage) than the twisted nematic liquid crystal. Therefore, it is possible to display an analog image, and it is also suitable for analog display.

(4) Furthermore, the response speed (several milliseconds to several tens of milliseconds) of the liquid crystal composite constituting the present invention is higher than that of the twisted nematic liquid crystal. Therefore, the spatial light modulator according to the present invention has a faster response speed than the conventional spatial light modulator described in the above item (II), and is suitable for displaying moving images.

(5) Further, in the present invention, by simultaneously scanning the target with a plurality of electron guns and with a certain time difference between the erasing electron beam and the writing electron beam,
A bright image with little shading can be displayed.

It also has advantages such as.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows a configuration of an embodiment of an electron beam writing type spatial light modulator according to the present invention. In the figure,
Reference numeral 1 denotes an electron gun comprising a cathode 2 and grids 3, 4, 5, 6 and 7, and an external coil 8 and a cathode 2
An electron beam is formed by the electrons generated in the above, the electron beam is accelerated, focused, and deflected, and the electron beam intensity is controlled according to an input signal to irradiate the electron to the surface of the target 9 and a two-dimensional charge is applied to the target surface. To form patterns,
It has a function of erasing the charge pattern. The portions of the cathode 2, the grids 3 and 4 form thermoelectrons radiated from the cathode surface in random directions into thin beams, and control the electron beam intensity by changing the potential difference between the constituent electrodes. The parts of the grids 5, 6 and 7 have the function of focusing the electron beam into small spots on the target surface.

Although the configuration of the electron gun shown in FIG. 1 is optically a unipotential type corresponding to a thin lens, a bipotential type (not shown) or a focusing coil (not shown) corresponding to a thick lens is used. It is also possible to make the beam spot diameter on the target surface smaller. In FIG. 1, 10 is a secondary electron collecting electrode (collector), 11 is a vacuum container having a transparent face plate 11 ', 12 is a voltage lead wire applied to the transparent electrode, and 13 is a voltage applied to the collector. A lead wire, 14 is an input signal lead wire, 15 is an electron beam, 16 is incident light, 17 is display light, and 27 is an ultraviolet cut filter for protecting the liquid crystal composite from ultraviolet light. _Vb is the potential of the transparent electrode, and _Vc is the potential of the collector.

FIG. 2 is a detailed configuration example of the target 9 of the embodiment shown in FIG. As shown in the drawing, the target 9 of the present embodiment is an element in which a transparent substrate 19, a transparent electrode 20, a liquid crystal composite 21, and a transparent dielectric layer 22 are sequentially adhered and integrated, and Is connected to a lead wire 12.

The above-described liquid crystal composite 21 used in the present invention is composed of a nematic liquid crystal, a cholesteric liquid crystal or a smectic liquid crystal 23 and any one of an ordinary refractive index, an extraordinary refractive index of the liquid crystal, and a refractive index when the liquid crystal is randomly aligned. It is composed of a transparent resin matrix 24 having an equivalent refractive index, and has a configuration in which the liquid crystal is dispersed and confined in the resin matrix, or a configuration in which the resin matrix is dispersed and confined in the liquid crystal. That is, the liquid crystal composite 21 of the present invention comprises, for example, a resin matrix 24 as shown in FIG.
The liquid crystal is spherical or non-spherical (the length is several hundred
Those that are confined within a nanometer to about 20 micrometers), those in which liquid crystal is confined in a so-called microcapsule shape in a resin matrix (not shown), or those in which a network-like resin matrix exists in liquid crystal (shown) No).

In the liquid crystal composite 21 having such a configuration, when the ordinary refractive index or the extraordinary refractive index of the liquid crystal 23 substantially matches the refractive index of the resin matrix 24, a state in which no electric field is applied to the liquid crystal composite 21 ( that is, the potential of the surface of the transparent dielectric layer 22 of the target 9, V _s, the state) of the V _s = V _b, since the refractive index of the liquid crystal 23 and the resin matrix 24 are different piles, light is scattered In a scattering state, on the other hand, in a state where an electric field is applied to the liquid crystal composite 21 (that is, a state of V _s ≠ V _b ), since the refractive indexes of the liquid crystal 23 and the resin matrix 24 match, the liquid crystal composite 21 has Become. In addition, liquid crystal 23
Refractive index and resin matrix 24 are randomly oriented
When the refractive indices of the liquid crystal 23 and the resin matrix 24 are substantially equal to each other, no electric field is applied to the liquid crystal composite 21.
Since the refractive indices of the liquid crystal composite 21 match, the liquid crystal composite 21 is in a light transmitting state.
The refractive indices of 3,24 differ, resulting in a light scattering state.

In the present invention, both types of liquid crystal composites can be used, but the former type, in which the ordinary refractive index or extraordinary refractive index of the liquid crystal 23 and the refractive index of the resin matrix 24 are more or less the same, is more preferable. In particular, a type in which the ordinary refractive index of the liquid crystal 23 and the refractive index of the resin matrix 24 are almost the same is optimal in terms of its performance.

The method of manufacturing the target including the liquid crystal composite shown in FIG. 2 is simpler than the conventional method of manufacturing a liquid crystal cell. For example, the target 9 can be formed by inserting the liquid crystal composite 21 between the transparent substrate 19 to which the transparent electrode 20 is attached and the transparent dielectric layer 22 and irradiating with ultraviolet light or heating. In this method, an alignment layer for uniformly aligning liquid crystal molecules is not required, and a large-area target can be easily formed.

Next, the operation of the electron beam writing type spatial light modulator having the liquid crystal composite 21 in which the ordinary refractive index of the liquid crystal 23 and the refractive index of the resin matrix 24 are substantially the same will be described. In the spatial light modulator according to the present invention, either the scattered light or the non-scattered light can be used as the display light. Hereinafter, the case where the non-scattered light is used as the display light will be described as an example.

First, a basic operation related to control of electric charges on the surface of the transparent dielectric layer 22 of the target 9 will be described. Liquid crystal composite 21
Electric field is applied, the transparent electrode 20 potential (V _b), the collector potential (V _c), depending on the secondary electron emission characteristics of the electron current of the beam 15, and the transparent dielectric layer 22. The secondary electron emission characteristics are acceleration voltage dependence characteristics of primary electrons (electrons that collide with the transparent dielectric layer) of the secondary electron emission ratio δ, and are expressed, for example, as shown in FIG. Assuming that the accelerating voltage corresponding to δ = 1 in the figure is a first crossing voltage (V ₁ ) and a second crossing voltage (V ₂ ), electrons having an energy corresponding to an accelerating voltage of V ₁ or less or V ₂ or more are generated. When colliding with the transparent dielectric layer, δ <1, and the surface of the transparent dielectric layer is negatively charged.

On the other hand, if electrons with energy corresponding to the increased V ₂ less accelerating voltage than V ₁ is impinging on transparent dielectric layer,
δ> 1, and the surface of the transparent dielectric layer is positively charged. Accordingly, the V _b, by controlling the like V _c and the electron gun potential, you are possible to determine the polarity and δ charges charged on the transparent dielectric layer surface. At this time, if the current value of the electron beam is also controlled by an electric signal input to the lead wire 14, a charge pattern can be formed on the surface of the transparent dielectric layer.

Next, the operation of the electron beam writing type spatial light modulator of the present invention will be specifically described. The operation method of the spatial light modulator is roughly classified into the following two methods.

(A) a V _c is fixed, (mode to form a charge pattern corresponding to the input signal to the transparent dielectric layer surface) write mode, and erase mode (transparent dielectric layer surface spatially uniformly charged or unsubstituted method for controlling the size of the V _b corresponding to the mode) for charging.

(B) a V _b is fixed, the method of controlling the V _c corresponding to the write mode and erase mode.

The method (A) includes the following four basic methods as a series of operations of erasing and writing.

(A) A method of forming a positive charge image on the surface of the transparent dielectric layer (b) A method of forming a positive charge inversion image on the surface of the transparent dielectric layer (c) A method of forming a negative charge image on the surface of the transparent dielectric layer ( d) Method of forming a negative charge inverted image on the surface of the transparent dielectric layer In the above methods (a) and (b), the collector potential V
_o is set to the second cross voltage V ₂ of Figure 3.

 Next, these four methods will be described in detail.

And (a) a transparent method of forming a positive charge image on the dielectric layer surface (a-1) setting the potential V _b of the erase mode transparent electrode 20 to _{V 2 (V b = V 2} ), a transparent dielectric layer 22 the potential V _s of the surface of a value of applied electric potential due to the positive charge generated by writing to V _2. That is, V _s ≧
Since V ₂ and δ ≦ 1, the surface of the transparent dielectric layer 22 is irradiated with the electron beam 15 to add a negative charge, and δ = 1 (V _s = V ₂ ) over the entire transparent dielectric layer. Can be. At this time, the charge on the surface of the transparent dielectric layer is 0, and the liquid crystal composite 21
Since no electric field is applied to the liquid crystal, the incident light is scattered by the liquid crystal composite 21. Therefore, the display image shows a dark state uniformly spatially.

(A-2) setting the potential V _b of the write mode transparent electrode 20 to the _{V 1 <V b <V 2} . At this time becomes the potential V _s even V ₁ <V _b <V ₂ of the surface of the transparent dielectric layer 22, [delta]> 1 become. Therefore, when the electron beam 15 collides with the surface of the transparent dielectric layer, the mirror surface is positively charged, and a positively charged image is formed. At this time, an electric field is formed in the liquid crystal composite 21 from the surface of the transparent dielectric layer 22 toward the transparent electrode 20, so that incident light passes through the liquid crystal composite 21 according to the electric field intensity. Therefore, the display image is in a bright state (a part where the electron beam is written is bright).

(B) a method of forming a positive charge inverted image on the transparent dielectric layer surface (b-1) setting the potential V _b of the erase mode transparent electrode 20 to the _{V 1 <V b <V 2} . At this time, V ₁ <V _s ≦ V ₂ is satisfied both at the potential of the surface of the transparent dielectric layer 22 where the electron beam is written and at the potential of the surface of the transparent dielectric layer where the electron beam is not written. . Therefore, δ ≧ 1, and the surface of the transparent dielectric layer is positively charged by electron beam irradiation. Secondary electrons emitted from the surface of the transparent dielectric layer are collected by a collector at a higher potential than the surface of the transparent dielectric layer. Transparent dielectric layer surface potential becomes a [delta] = 1 reaches V _2, a transparent dielectric layer surface is uniformly positively charged. At this time, an electric field from the transparent dielectric layer 22 to the transparent electrode 20 is formed in the liquid crystal composite 21, so that incident light is transmitted without being scattered by the liquid crystal composite. Therefore, the display image is uniformly bright.

(B-2) setting the potential V _b of the write mode transparent electrode 20 to the V ₂ <V _b. At this time,
The surface potential of the transparent dielectric layer 22 also becomes V _s > V ₂ and δ <1. Accordingly, a negative charge is applied to the surface of the transparent dielectric layer 22 in accordance with the current value of the writing electron beam 15, thereby neutralizing the positive charge formed uniformly in advance, and an inverted image of the positive charge is obtained. It is formed. Here, when light enters the liquid crystal composite 21, the light is scattered in accordance with the amount of attenuation of the charged positive charges, and the display image is in a dark state (the portion where the electron beam is written is dark).

And (c) a transparent dielectric layer method for forming a negative charge image on a surface (c-1) setting the potential V _b of the erase mode transparent electrode 20 to _{V 2 (V b = V 2} ), a transparent dielectric layer 22 the potential V _s of the surface of a value of applied potential by the negative charge generated by writing to V _2. That is, V _s ≦
Since V ₂ and δ ≧ 1, the surface of the transparent dielectric layer 22 is irradiated with the electron beam 15 to add a positive charge, and δ = 1 (V _s = V ₂ ) over the entire transparent dielectric layer. Can be. At this time, the charge on the surface of the transparent dielectric layer is 0, and the liquid crystal composite 21
Since no electric field is applied to the liquid crystal, the incident light is scattered by the liquid crystal composite 21. Therefore, the display image shows a dark state uniformly spatially.

(C-2) setting the potential of the write mode transparent electrode 20 to V _b> V _2. At this time, the manifestation potential of the transparent dielectric layer 22 is V _s > V ₂ and δ <1.
Therefore, a negative charge image is formed on the surface of the transparent dielectric layer according to the current value of the writing electron beam. That is, since an electric field is formed from the transparent electrode toward the transparent dielectric layer, the light incident on the liquid crystal composite 21 is transmitted according to the amount of the charged negative charges, and the displayed image is in a bright state (where the electron beam is written). (The shaded area becomes bright).

And (d) forming a negative charge inverted image on the transparent dielectric layer surface (d-1) setting the potential of the erase mode transparent electrode 20 to V _b> V _2. At this time, V _s
Since the ≧ V ₂ becomes [delta] ≦ 1. Thus the surface of the electron beam irradiation by a transparent dielectric layer 22, charges the negative charge until the voltage V _s becomes V _2. Since an electric field from the transparent electrode 20 to the transparent dielectric layer 22 is formed in the liquid crystal composite 21, the incident light is transmitted, and the displayed image is uniformly bright.

(D-2) setting the potential of the write mode transparent electrode 20 to V _b = V _2. At this time, V _s <
Since the V ₂ δ> 1 to become. Therefore, the portion irradiated with the electron beam is neutralized by positive charges, and a negative charge inverted image is formed on the surface of the transparent dielectric layer 22. Since the electric field in the liquid crystal composite 21 is weakened only at the portion irradiated with the electron beam, the display image is in a dark state (the portion where the electron beam is written is dark).

Next, the method (B) includes the following two methods.

(E) Method of forming negative charge reversal image on transparent dielectric layer surface (f) Method of forming positive charge reversal image on transparent dielectric layer surface In the above methods (e) and (f), the potential of the transparent electrode
V _b is set to _{V 1 <V b <V 2} .

 Hereinafter, these methods will be described in detail.

(E) a transparent dielectric layer method for forming a negative charge reversal image on a surface (e-1) and the potential V _c of the erase mode collector 10 to the negative polarity, the electron beam having a sufficiently large current value of the transparent dielectric layer 22 Irradiate the surface. Under the condition of V ₁ <V _b <V ₂ , the secondary electron emission ratio of the transparent dielectric layer is δ> 1, but the emitted secondary electrons are not collected by the collector because V _c is negative. It is pushed back to the surface of the transparent dielectric layer. Potential of thus transparent dielectric layer surface is reduced to V _1, the transparent dielectric surface is charged uniformly negative. At this time, an electric field is generated in the liquid crystal composite 21 from the transparent electrode 20 to the transparent dielectric layer 22, and the incident light is transmitted without being scattered. Therefore, the display image is uniformly bright.

(E-2) the potential V _c of the write mode collector 10 to the positive polarity, an electron beam writing. If _Vc is made sufficiently large to collect secondary electrons emitted from the surface of the transparent dielectric layer 22, a positive charge will be generated according to the current value of the writing electron beam under the condition of δ> 1. To neutralize the negative charge that has been uniformly formed in advance, and an inverted image of the negative charge is formed. Here, when light is incident on the liquid crystal composite 21, the light is scattered in accordance with the amount of neutralization, and the display image is in a dark state (the part where the electron beam is written is dark).

(F) a method of forming a positive charge inverted image on the transparent dielectric layer surface (f-1) the potential V _c of the erase mode collector 10 and the positive polarity, the electron beam having a sufficiently large current to the transparent dielectric layer 22 Irradiate. V ₁ <
From the condition of V _b <V ₂ (δ> 1), if the potential of V _c is sufficiently increased and the secondary electrons emitted from the transparent dielectric layer surface are collected by the collector, the potential of the transparent dielectric layer surface becomes increased to V _2, the transparent dielectric layer surface is uniformly positively charged. At this time, an electric field is generated in the liquid crystal composite 21 from the transparent dielectric layer toward the transparent electrode, and the incident light is transmitted without being scattered. Therefore, the display image is uniformly bright.

(F-2) the potential V _c of the write mode collector 10 to the negative polarity, an electron beam writing. From the condition of V ₁ <V _b <V ₂ , the secondary electron emission ratio of the transparent dielectric layer 22 is δ> 1, but the emitted secondary electrons are
Since _Vc has negative polarity, it is pushed back to the surface of the transparent dielectric layer without being collected by the collector 10. Therefore, the positive charges formed uniformly beforehand are neutralized, and an inverted image of the positive charges is formed. Here, when light is incident on the liquid crystal composite 21, the light is scattered in accordance with the amount of neutralization, and the displayed image is in a dark state (the part where the electron beam is written is dark).

When displaying images and data patterns continuously, there is a method of combining these methods in addition to the basic method of repeating one of the above six methods (a) to (f). . In particular, the method of combining (a) and (c) or (b) and (d), or (e) and (f), and using them alternately, has the same display time of the two combined methods, and When the correlation between images adjacent to each other on the time axis is strong, such as a TV image, the DC electric field component applied to the liquid crystal composite is minimized, and the practical life of the liquid crystal composite can be maximized. It is a way.

FIG. 4 shows another example of the configuration of the electron beam writing type spatial light modulator according to the present invention. In the figure, 1 'is a writing electron gun, 1 "is an erasing electron gun, 15' is a writing electron beam, and 15" is an erasing electron beam. In the configuration shown in the figure, it is necessary to set the potentials of the two electron guns so that the acceleration voltage of the erasing electron beam satisfies the conditions described in the above two basic operation methods (A) and (B). is there. For example, when a positive charge image or a negative charge image is formed on the surface of the transparent dielectric layer of the target 9 (method (a) or (c)), the acceleration voltage of the erasing electron beam increases It is necessary to set the potential of the erasing electron gun so as to match the second crossing voltage (V ₂ ) at which δ becomes 1.

In the spatial light modulator of the present invention shown in FIG. 4, since writing and erasing are performed using a plurality of electron guns, the erasing is performed in comparison with the spatial light modulator using a single electron gun shown in FIG. The scanning electron beam and the writing electron beam can be scanned simultaneously with a certain time difference. That is, the past charged state on the target is first erased by the erasing electron beam, and then the target is charged by the writing electron beam. By performing this operation continuously over the entire screen, the charging time of all pixels can be made the same, and a bright image without shading can be displayed.

Further, the spatial light modulator shown in FIG. 4 has a configuration in which the traveling directions of the electron beams emitted from the two electron guns are significantly different from each other. It is also possible to irradiate different places on the target with the two electron guns.

Further, in the spatial light modulator shown in FIG. 4, an anode electrode (not shown) for assisting the acceleration of electrons along the wall surface of the vacuum vessel 11 between the two electron guns 1 'and 1 "and the target 9. It is also possible to provide.

The aperture 29 in the optical system of the electron beam writing type spatial light modulator according to the embodiment of the present invention shown in FIGS. 1 and 4 described above blocks most of the scattered light and displays only the non-scattered light. And a function of improving the contrast of the display screen.

FIG. 5 shows another configuration example of the target 9 of the beam writing type spatial light modulator according to the present invention. In the figure, 19 '
Is a transparent dielectric thin film, which accumulates and neutralizes charges by secondary electron emission performed in the transparent dielectric layer of the target 9 shown in FIG. 1, FIG. 2 or FIG. This target has an advantage that the resolution of the displayed image is higher than that of the target having the structure shown in FIG. 1, FIG. 2 or FIG.

An example of a method for forming the target 9 including the liquid crystal composite shown in FIG. 5 will be described below.

(A) First, a transparent electrode 20 is attached to one surface of a transparent substrate 19 by using a vapor deposition method or a high frequency sputtering method.

(B) Next, a liquid crystal, a monomer, a polymerization initiator, and the like are mixed, and the mixed solution is uniformly applied to the surface of the transparent electrode by using a spin coating method or the like.

(C) The liquid crystal composite 21 in which the resin matrix 24 and the liquid crystal 23 are separated and dispersed from the liquid mixture is formed by an ultraviolet irradiation method or a heating method.

(D) The liquid crystal on the surface of the liquid crystal composite 21 is removed.

(E) A mixture of a monomer and a polymerization initiator is applied to the surface of the liquid crystal composite 21 by spin coating or the like.

(F) A transparent resin layer is formed from this mixture by an ultraviolet irradiation method or a heating method.

FIG. 6 shows another configuration example of the target of the electron beam writing type spatial light modulator according to the present invention. In the configuration shown in the figure, a transparent electrode 20 is attached to a face plate 11 'of a vacuum vessel 11, and a liquid crystal composite 21 and a transparent dielectric layer 22 are further adhered thereon.

As still another configuration example of the target of the electron beam writing type spatial light modulator according to the present invention, there is a configuration (not shown) in which a thin film material (for example, an MgO thin film) having a large secondary electron emission ratio δ is attached to the surface of the target. . For example, FIG.
2, 4 and 6, the thin film material is adhered to the surface of the transparent dielectric layer 22 in FIG. 5 and to the surface of the transparent dielectric thin film 19 'in FIG. Efficiency can be increased.

Further, a target having the features of a plurality of the target configurations shown in FIGS. 2, 5, and 6, and a target configuration in which a thin film material having a large secondary electron emission ratio δ is attached to the target surface; By using one or more electron guns, it is also possible to construct an electron beam writing type spatial light modulator having a combination of the characteristics of the various targets described above.

[Effects of the Invention] As described above, according to the present invention, the following specific effects can be obtained.

In the electron beam writing type spatial light modulator of the present invention, since a polarizing plate is not required, a display image is twice or more brighter than that of a conventional electron beam writing type spatial light modulator using a polarizing plate.

Since an alignment layer for arranging liquid crystal molecules used in a conventional electron beam writing type spatial light modulator is not required, and a large-area target can be easily manufactured, a high-resolution, bright, and large-area Can be easily displayed.

Since the phase of light is not modulated by using the birefringence effect of the liquid crystal, the unevenness of the display screen caused by the uneven thickness of the liquid crystal layer is small.

Since it is not necessary to enhance the parallel characteristics of the display light incident on the spatial light modulator, and the emission area of the display light source may be relatively large, a bright display image can be obtained.

The response of the electron beam writing type spatial light modulator of the present invention is faster than that of a spatial light modulator using a twisted nematic liquid crystal. That is, the total rise and fall time of the spatial light modulator used in the present invention is set between several milliseconds and several tens of milliseconds by controlling the size of the granular liquid crystal in the liquid crystal composite, It is much shorter than the total rise and fall times (50 milliseconds to hundreds of milliseconds) of a conventional electron beam writing spatial light modulator using a twisted nematic liquid crystal.

Since the value of γ of the liquid crystal composite used in the present invention is small, it is optimal for analog light modulation. On the other hand, the twisted nematic liquid crystal constituting the conventional electron beam writing type spatial light modulator has a large γ, which is not suitable for analog light modulation.

By using a plurality of electron guns and simultaneously scanning the target with a certain time difference between the erasing electron beam and the writing electron beam, a bright image without shading can be displayed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an electron beam writing type spatial light modulator according to the present invention, FIG. 2 is a perspective view showing an example of a configuration of a target of the components shown in FIG. FIG. 4 is a view showing an example of secondary electron emission characteristics of a transparent dielectric layer as a component of the target shown in FIG. 2. FIG. FIGS. 5, 5 and 6 are schematic diagrams showing another embodiment of the target of the electron beam writing type spatial light modulator according to the present invention. FIGS. 7 to 11 are each a document which discloses the prior art. FIG. 1 is a schematic diagram showing a configuration of a conventional electron beam writing type spatial light modulator described in FIG. 1 ... electron gun, 2 ... cathode, 3-7 ... grid,
8 ... External coil, 9 ... Target, 10 ... Secondary electron collecting electrode (collector), 11 ... Vacuum container, 11 '...
Transparent faceplate, 12-14 ... Lead wire, 15 ...
Electron beam, 16: Incident light, 17: Display light, 26: Light source, 27: UV cut filter, 28: Lens, 30
……screen.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-282719 (JP, A) JP-A-2-96714 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/1333 G02F 1/13 102

Claims (6)

(57) [Claims] 1. A refractive index equivalent to one of a normal refractive index, an extraordinary refractive index of a nematic liquid crystal, a cholesteric liquid crystal or a smectic liquid crystal, and a refractive index when the liquid crystal is randomly aligned, between a transparent dielectric layer and a transparent electrode. A liquid crystal composite having a structure in which the liquid crystal is dispersed and confined in a transparent resin matrix having a high refractive index, or a structure in which the resin matrix is dispersed and confined in the liquid crystal is adhered to the transparent dielectric layer and the transparent electrode. And a single or multiple electron gun consisting of one or more grids and a cathode for generating electrons, forming, accelerating, and focusing an electron beam, and controlling the intensity of the electron beam according to an input signal. A vacuum container containing a secondary electron collecting electrode for controlling electric charge on the surface of the transparent dielectric layer, and deflecting the electron beam. Electron beam drafting transmissive spatial light modulator tube combination of electron beam deflection system. 2. The electron beam writing type transmissive spatial light modulator according to claim 1, further comprising a target in which a transparent dielectric layer, a transparent electrode, a liquid crystal composite, and a transparent dielectric thin film layer are sequentially adhered. . 3. An electron beam writing type transmissive spatial light modulator according to claim 1, further comprising a target using a face plate of a vacuum vessel instead of the transparent dielectric closely attached to the transparent electrode. . 4. An electron beam writing type transmission spatial light modulator according to claim 1, wherein a thin film material having a high secondary electron emission ratio is adhered to the target surface. 5. An electron beam writing system according to claim 1, wherein said optical system has an aperture for passing non-scattered light and blocking scattered light or an aperture for effecting the opposite operation. Transmission type spatial light modulator. 6. The electron beam writing type transmissive space light according to claim 1, wherein the target is simultaneously scanned with a certain time difference between the erasing electron beam and the writing electron beam. Modulation tube.