JPH06324361A - Laser manipulation light control element - Google Patents

Abstract

PURPOSE:To prevent coloring particles from attaching to substrates, to prolong the life of repetitive operations and to suppress partial disturbances of displays. CONSTITUTION:Dispersion media 31 and dispersion system layer 3 having coloring dispersion particles 32 having refractive index higher than dispersion media 31 are arranged between transparent substrates 1a, 1b in a light control element 10. The substrate 1a of an incident side is provided with a lens group 11 in which plural lenses are arranged in a direction parallel with the plane of substrates. A laser irradiating means 20 irradiates with a laser light in a prescribed pattern corresponding to the arrangement of the lens group 11. When the laser irradiation is 'OFF'. the color of coloring dispersion particles dispersed uniformly is displayed. When the laser irradiation is 'ON', the display becomes to be a transparent display since coloring dispersion particles 32 are grasped at irradiated parts due to the laser manupulation principle. An uniform display is attained since focussing positions of laser lights converged by lenses in the lens group 11 can be controlled respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser manipulation light control device utilizing laser manipulation of fine particles. The laser manipulation light control device of the present invention can be used for display devices, optical switches, light control glass, and the like.

[0002]

2. Description of the Related Art An electrophoretic display element has been conventionally known as a light-adjusting element in which color can be attached and detached. As this electrophoretic display element, for example, as shown in FIGS. 14 and 15, a pair of transparent substrates 81a and 81b and a pair of transparent electrode layers 82a and 82b formed on the inner surfaces of the substrates 81a and 81b.
And a spacer 83 that seals the peripheral portions of both substrates 81a and 81b to form a cell space with both substrates 81a and 81b.
And the dispersion system layer 84 enclosed in the cell space is disclosed in Japanese Utility Model Laid-Open No. 1-88896.

In the above electrophoretic display element, the dispersion system layer 84
Are electrophoretic particles 86 composed of a dispersion medium 85 and positively charged particles 86a having a positive surface charge and negatively charged particles 86b having a negative surface charge dispersed on the dispersion medium 85.
And a dye (not shown) which is dissolved in the dispersion medium 85 and becomes a background color. The positively charged particles 86a and the negatively charged particles 86b act as colored particles, and the positively charged particles 8
As 6a, for example, titanium dioxide showing white is used,
As the negatively charged particles 86b, for example, a pigment showing yellow is used.

In this electrophoretic display element, the electrophoretic particles 86 are uniformly dispersed in the dispersion medium 85 when no voltage is applied (the state shown in FIG. 14), and therefore, the electrophoretic particles are dissolved in the dispersion medium 85. Display the background color of the dye. Then, when a negative voltage is applied to one electrode layer 82a and a positive voltage is applied to the other electrode layer 82b through the terminals 87a and 87b, the positively charged particles 86a adhere to the one electrode layer 82a and become negative. The charged particles 86b adhere to the other electrode layer 82b (state of FIG. 15). Therefore, in this case, the white color due to the positively charged particles 86a is displayed when viewed from the one electrode layer 82a side, and the yellow color due to the negatively charged particles 86b is displayed when viewed from the other electrode layer 82b side. Further, the display color can be reversed by reversing the application of the positive and negative electrodes.

[0005]

In the electrophoretic display device as described above, by applying voltage, charged particles as colored particles are attached to the electrode layer to form a colored charged particle layer on the surface of the electrode layer. Display colors are generated. That is, the charged particles are attached to and detached from the electrode layer depending on whether or not a voltage is applied. Therefore, when the electrophoretic display element is repeatedly operated, the charged particles are repeatedly attached to and detached from the electrode layer, and as a result, some of the charged particles remain attached to the surface of the electrode layer and the display color is disturbed. , The responsiveness may decrease.

[0006] Therefore, as a result of earnest research to solve such problems, the present inventor recalled that the laser manipulation technology of fine particles was used for a light control element, and the adhesion of colored particles to a substrate was eliminated. , Completed a laser manipulation light control element capable of improving the repeated operation life, and filed a prior application (Japanese Patent Application No. 4-327999).
issue). In this laser manipulation light control element, a dispersion layer having a dispersion medium and colored dispersion particles dispersed in the dispersion medium and having a higher refractive index than the dispersion medium is disposed between at least one pair of transparent substrates. And a laser irradiation unit that is disposed on one of the light control cells on the side of the transparent substrate and that irradiates the light control cell with condensed laser light in a predetermined pattern. .

In this light control device, the colored dispersed particles are uniformly dispersed in the dispersion system layer without being irradiated with the laser, and the color of the colored dispersed particles is displayed. Then, when the condensed laser light is irradiated in a predetermined pattern, according to the basic principle of laser manipulation of fine particles to be described later, colored dispersed particles are laser-trapped and agglomerated at the position where the laser light is irradiated, and the laser light is emitted. The colored dispersed particles do not exist in the non-irradiated areas. Therefore, when the light control cell is irradiated with the laser light, the transmittance of the light control element can be made variable by controlling the irradiation pattern of the laser light, the irradiation range, and the like.

Here, according to the basic principle of laser manipulation of fine particles, the fine particles are captured toward the focal position of the focused laser beam, so that the finer the particles are, the closer they can be captured. However, in the above-mentioned laser manipulation light control element, the laser light condensed by the condenser lens is scanned by the galvano lens and is applied to the light control cell in a predetermined pattern. Therefore, in the case of a particularly large dimming cell, the distance from the scanning position of the laser light differs between the central portion and the peripheral portion of the dimming cell, and the focal position of the laser light deviates according to the traveling distance of the light. . For example, when the scanning position is made to correspond to the central portion of the light control cell, the laser light irradiated to the peripheral portion of the light control cell has a longer traveling distance than that of the central portion due to the oblique incidence, The focus position also shifts toward this side. In this case, in the peripheral portion of the light control cell, since the capturing power of the fine particles by the laser light is weaker than in the central portion, the transmittance of the light control element at the time of laser irradiation is reduced in the peripheral portion, which causes partial display disturbance. Occurs.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to eliminate the adhesion of colored particles to the substrate, improve the repeated operating life, and suppress partial display disturbance. An object is to provide an optical element.

[0010]

A laser manipulation dimming device of the present invention which solves the above problems is a dispersion medium and a dispersion medium dispersed in the dispersion medium between a pair of substrates, at least one of which is transparent. A dispersion layer having colored dispersed particles having a high refractive index is arranged, and a lens group having a plurality of lenses arranged in a direction parallel to the surface of the transparent substrate is provided on one side of the transparent substrate. And a laser irradiation unit which is disposed on one of the light control cells on the transparent substrate side and which irradiates the light control cells with laser light in a predetermined pattern corresponding to the arrangement of the lens groups. It is characterized by.

[0011]

Before explaining the function of the light control device of the present invention, the basic principle of laser manipulation of fine particles will be described. As shown in FIG. 8 in which the laser light collected by the condenser lens captures the spherical fine particles, the laser light is refracted by passing through the fine particles having a higher refractive index than the dispersion medium. At this time, as shown in FIG. 9, the momentum of light is ΔP (vector ΔP = vector Pb−vector P) before and after the incidence.
Only a) changes. This changed momentum is transferred to the fine particles as −ΔP according to the law of conservation of momentum.
As a result, the fine particles have a force of capturing the fine particles represented by Fa and Fb. Strictly speaking, the reflection of the laser beam on the surface of the fine particles must be taken into consideration, but in reality, the influence of the reflection is small and can be ignored. Then, as described above, when the refractive index of the fine particles is higher than that of the dispersion medium, the sum F thereof is directed in the direction of the focal position f of the laser light, and as a result, the fine particles are captured by the laser. On the contrary, when the refractive index of the fine particles is smaller than that of the dispersion medium, the direction of the force is reversed and the fine particles are not captured by the laser.

Therefore, when the refractive index of the fine particles is higher than that of the dispersion medium, how the fine particles are captured depends on the positional relationship between the focal position f of the irradiated laser beam and the captured fine particles, as shown in FIGS. As shown in. FIG. 10 shows a case where the focal position f of the laser light is inside the fine particles and is located on the incident side from the center of the fine particles, and FIG. 11 is where the focal position f of the laser light is inside the fine particles and is emitted from the center of the fine particles. FIG. 12 shows a case where the focal position f of the laser light is outside the fine particles and is located on the incident side of the fine particles, and FIG. 13 shows a case where the focal position f of the laser light is outside the fine particles. , Shows the case of being located on the emission side of the fine particles.

In the light control device of the present invention, the colored dispersed particles are uniformly dispersed in the dispersion layer in a state where the laser is not irradiated from the laser irradiation means, and the color of the colored dispersed particles is displayed. Then, on one transparent substrate side of the light control cell,
When the laser light is emitted from the laser irradiation means in a predetermined pattern according to the arrangement of the lens groups provided on the transparent substrate side, the laser light is condensed by each lens of the lens group and is incident on the dispersion system layer. . As a result, according to the principle of laser manipulation described above, the colored dispersed particles are laser-trapped and agglomerated at the locations irradiated with the focused laser light. In this way, by irradiating the focused laser light in a predetermined pattern, the dimming cell can be divided into a portion irradiated with the laser light and a portion not irradiated with the laser light. The colored dispersed particles in the dispersion layer are trapped by the trapping force directed to the focal position of the laser light, and as a result, they are trapped side by side in the thickness direction of the light control cell at the portion irradiated with the laser light. Further, the colored dispersed particles in the dispersion layer which are not irradiated with the laser light are similarly captured when they move by Brownian motion and enter the range irradiated with the laser light. In this way, the colored dispersed particles in the light control cell are all present in the portion irradiated with the laser light, and the colored dispersed particles are absent in the portion not irradiated with the laser light. Therefore, when the light control cell is irradiated with the laser light, the transmittance of the light control element can be made variable by controlling the irradiation pattern of the laser light, the irradiation range, and the like.

Therefore, the light control device of the present invention can switch the color display and the transparent display of the colored dispersed particles and can change the transmittance depending on the presence or absence of laser irradiation. Since the light control element of the present invention has a lens group in which a plurality of lenses are arranged in a direction parallel to the substrate surface on one (incident side) transparent substrate side, each lens of the lens group is The focus position of the focused laser light can be arbitrarily controlled by the lens shape. Therefore, if the shape of each lens in the lens group is adjusted so that the focus position of the laser light is aligned in the thickness direction of the dimming element over the entire dimming element, the capturing power of fine particles over the entire dimming element can be obtained. It can be uniform.

Therefore, in the light control element of the present invention, by adjusting the shape of each lens forming the lens group, the particle capturing power, that is, the transmittance of the element is partially adjusted.
In addition, it can be controlled arbitrarily, and uniform display of the entire device is possible. The pair of substrates may be a transparent substrate and a colored substrate, or by adding a dye to the dispersion medium system layer, the display color of the light control element during laser irradiation may be the color of the dye or the colored substrate. It is possible to change the coloring form in various ways.

[0016]

EXAMPLES Specific examples of the present invention will be described below.
As shown in FIGS. 1 and 2, the light control element of the present embodiment mainly includes a light control cell 10 and a laser irradiation means 20. The dimming cell 10 includes a pair of transparent substrates 1a and 1b.
And a spacer 2 disposed on the peripheral portions of both substrates 1a and 1b for sealing, and a dispersion system layer 3 enclosed in the cell space formed by both substrates 1a and 1b and the spacer 2. .

One transparent substrate 1a has a thickness of 2 mm and a length of 6 mm.
It is a soda lime glass substrate having a width of 0 mm and a width of 120 mm. On the outer surface of the transparent substrate 1a, lenses are arranged in a direction parallel to the substrate surface, pitch 1 mm, focal length:
A 2.05 mm convex cylindrical lens (semi-cylindrical convex lens) group 11 is formed. Therefore, the laser beam emitted from the laser irradiating means 20 in a predetermined pattern is condensed by each lens, and is substantially centered in the thickness direction of the dispersion layer 3 within the dispersion layer 3 of the light control cell 10. It is designed to focus on (see Fig. 4).

The other transparent substrate 1b has a thickness of 2 mm and a length of 6 mm.
It is a flat plate made of 0 mm and 120 mm wide soda lime glass. The substrate 1b is on the display side (see FIGS. 1 and 2).
The right side of), the substrate 1b is hereinafter referred to as the display side substrate 1b, and the substrate 1a is referred to as the back side substrate 1a. Spacer 2
Is made of a polyethylene terephthalate film having a thickness of 100 μm, holds the display-side substrate 1b and the back-side substrate 1a at regular intervals, and seals the peripheral portions of both substrates 1a and 1b. It should be noted that the substrate 2 is
To seal the peripheral part of 1b, epoxy adhesive or UV
It can be performed using a curable adhesive.

The dispersion system layer 3 comprises a dispersion medium 31 and the dispersion medium 3
1 and colored dispersed particles 32 dispersed therein.
The dispersion medium 31 is water, and the colored dispersion particles 32 are fine particles of polymethylmethacrylate having a particle size of 1 μm and colored black. The colored dispersed particles 32 are contained in the dispersion layer 3 in an amount of 1 wt%. The refractive index of polymethylmethacrylate used as the colored dispersed particles 32 is 1.49, and the dispersion medium 31
The refractive index of water is greater than 1.33.

The laser irradiation means 20 is arranged on the rear substrate 1a side of the light control cell 10, and includes a laser oscillator 21 and
It is composed of a galvanometer mirror 23. As the laser oscillator 21, a CW Nd ³⁺ : YAG laser (wavelength 1064 nm) was used. As shown in FIG. 3, the galvano mirror 23 has a first mirror 23a that is rotatable in the x-axis direction by computer control, a second mirror 23b that is also rotatable in the y-axis direction by computer control, and a second mirror 23b. It is composed of a computer controller 23c for controlling the first mirror 23a and the second mirror 23b. By rotating the first mirror 23a and the second mirror 23b by the computer controller 23c, respectively, the laser light from the laser oscillator 21 is sequentially reflected by the first mirror 23a and the second mirror 23b to perform high-speed sweeping.
The light control cell 10 is irradiated with a predetermined pattern. In the present embodiment, the galvano mirror 23 is controlled by the computer control unit 23c so that the irradiation pattern has a stripe shape corresponding to the pitch of each lens of the cylindrical lens group 11 provided on the rear substrate 1b.

The light control element of this embodiment having the above-mentioned structure is
The colored dispersed particles 32 are uniformly dispersed in the dispersion system layer 3 in the state where the laser is not emitted from the laser oscillator 21, and the colored dispersed particles 32 are displayed in black (state in FIG. 2). Then, when the laser oscillator 21 is operated while the computer controller 23c controls the rotation of the first mirror 23a and the second mirror 23b of the galvanometer mirror 23, the laser light passes through the galvanometer mirror 23, whereby the cylindrical lens group 11 The back side substrate 1a of the light control cell 10 is irradiated with a stripe-shaped irradiation pattern corresponding to the pitch. Then, the laser light condensed by each lens of the rear substrate 1a uniformly forms a focal point f at substantially the center of the dispersion layer 3 in the thickness direction over almost the entire display surface of the light control cell 10. As a result, according to the principle of laser manipulation described above, the trapping force F acts on the colored dispersed particles 32 irradiated with the laser beam in the direction of the focus position f, and as a result, the colored dispersed particles 32 are irradiated with the laser beam. Thus, the light control cells 10 are captured side by side in the thickness direction. Further, the colored dispersed particles 32 in the portion not irradiated with the laser light are similarly captured when they move by Brownian motion and enter the range irradiated with the laser light.
Moreover, the above-mentioned trapping force F works uniformly over almost the entire display surface of the light control cell 10 because the focus position f is controlled to be substantially uniform, so that the colored dispersed particles 32 are trapped almost uniformly over the entire display surface. Is possible. In this way, all the colored dispersed particles 32 in the light control cell 10 are captured by the portion irradiated with the laser light and aggregate in a stripe shape. As a result, the light control device of the present example became transparent display.

Therefore, the light control device of this embodiment can display the colored dispersed particles 32 in black when the laser oscillator 21 is turned off and can display it in a transparent state when the laser oscillator 21 is turned on. (Evaluation of Transmittance) With respect to the light control element of the above-described example, the transmittance when the laser oscillator 21 was OFF and when it was ON was measured at the central portion and the peripheral portion of the cell, respectively. The results are shown in Table 1.

For comparison, a light control element similar to that of the above-described embodiment was produced except that a flat glass substrate having no lens group 11 was used as the rear substrate 1a. Then, as in the above embodiment, the laser oscillator 21 is turned off.
At the time of turning on and at the time of turning on, the transmittance was measured at the central portion and the peripheral portion of the cell. The results are also shown in Table 1.

[0024]

[Table 1] As is clear from Table 1, in the light control device of the present embodiment, the transmittance when the laser oscillator 21 is ON is equal in the central portion and the peripheral portion of the cell, and the colored dispersed particles are uniformly captured throughout the cell. Was confirmed.

Further, the light control element of this example was also good in the result of the durability test in which the ON / OFF of the laser irradiation was repeated 10 ³ times. (Other Examples) In the above examples, the lenses of the cylindrical lens group 11 having the same curved surface shape were used. Therefore, as shown in FIG. 5, when light is incident on the lens located at the periphery of the cell, points A and B on the lens
At point A, the incident angle θ ₁ at point A and the incident angle θ at point B
_It makes a big difference with _1B . Therefore, strictly speaking, the focal position at the peripheral portion of the cell tends to be slightly displaced to the incident side from the focal position at the central portion of the cell.

In order to eliminate the shift of the focal point position, as shown in FIG. 6, the curved surface shape of each lens is changed from the central portion of the cell toward the peripheral edge portion so that the focal point position f is distributed throughout the cell. It is also possible to tie it accurately at the center of the thickness direction 3. This cylindrical lens group 1
The shape of the lens located in the peripheral portion of the cell in 1'is enlarged and shown in FIG. As can be seen from FIG. 7, since the curved surface shapes at points A and B on the lens are changed, there is a large difference between the incident angle θ _1A at point A and the incident angle θ _1B at point B. Without being born, the focus position f can be shifted to a distance.
Therefore, the focus position f can be more accurately controlled to the center of the dispersion system layer 3 in the thickness direction in the central portion and the peripheral portion of the cell.

In the above embodiment, the lens group 11 is formed on the outer surface of the rear substrate 1a. However, the rear substrate 1a is a simple flat substrate and the rear substrate 1a is formed. It is also possible to dispose a transparent substrate having a lens group at a position near the side as a separate body. Further, in the above-described embodiment, the example in which the lens group 11 is provided over the entire surface of the substrate 1a has been described, but it is also possible to dispose the lens group only in a necessary portion.

Further, in the above-mentioned embodiment, the display side substrate 1b is used as a colored substrate and observed from the back side substrate 1a side, or a dye is added to the dispersion medium system layer so that the laser irradiation is performed. That is, the color of the colored substrate or the color of the dye can be displayed during the transparent display. Further, by the computer control of the galvano mirror 23, the irradiation pattern can be dot-shaped or grid-shaped, and each lens of the lens group 11 can be hemispherical. Similarly to, it is possible to switch between transparent display and colored display depending on the presence or absence of laser irradiation. Also, galvano mirror 23
It is also possible to change the width of the irradiation range by computer control in the above, and thus it is possible to change the transmittance during transparent display.

Furthermore, in the above embodiment, an example was shown in which polymethylmethacrylate was used as the colored dispersion particles and water was used as the dispersion medium. Basically, the refractive index of the colored dispersion particles is the refractive index of the dispersion medium. If it is higher than the above, the particles can be captured according to the principle of laser manipulation. Therefore, the combination of the colored dispersed particles and the dispersion medium can be variously changed as long as this condition is satisfied. For example, in the case of an aqueous dispersion medium, as the colored dispersion particles, in addition to acrylic fine particles,
Polystyrene, titanium dioxide, glass beads, etc. can be used.

[0030]

As described above in detail, the light control device of the present invention can switch the color display and the transparent display of the colored dispersed particles and can change the transmittance depending on the presence or absence of laser irradiation. . Moreover, unlike the conventional electrophoretic display element, it is not necessary to attach the colored fine particles to the substrate, and therefore, the repeated operation life and the display performance are excellent as compared with the conventional electrophoretic display element.

In the light control element of the present invention, since the laser light is focused by each lens of the lens group provided on the incident side of the light control cell, the focal position of each laser light is arbitrarily controlled. can do. Therefore, if the focal position is uniformly controlled in the cell center portion and the cell peripheral portion, uniform display can be performed over the entire dimming cell.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view schematically showing the overall structure of a light control device according to the present embodiment and illustrating a state when laser irradiation is ON.

FIG. 2 is a partial cross-sectional view schematically showing the overall structure of the light control device according to the present embodiment and illustrating a state when laser irradiation is OFF.

FIG. 3 is a diagram schematically illustrating a galvanometer mirror of the light control device according to the present embodiment.

FIG. 4 is an explanatory diagram showing focal positions at a cell center portion and a cell peripheral portion in the light control device according to the present embodiment.

FIG. 5 is an explanatory diagram showing a state where laser light is incident on a lens in a cell peripheral portion in the light control device according to the present embodiment.

FIG. 6 is an explanatory diagram showing focus positions at a cell center portion and a cell peripheral portion in a light control device according to another example.

FIG. 7 is an explanatory diagram showing a state where laser light is incident on a lens in a cell peripheral portion in a light control element according to another example.

FIG. 8 is an explanatory diagram showing how particles are captured by a focused laser beam.

FIG. 9 is an explanatory diagram showing a state in which the momentum of light changes before and after being incident when laser light passes through particles having a higher refractive index than the surroundings.

FIG. 10 is an explanatory diagram showing a trapped state in the case where the focal position f of the laser light is inside the fine particles and is located on the incident side from the center of the fine particles.

FIG. 11 is an explanatory diagram showing a trapped state in the case where the focal position f of the laser light is inside the fine particles and is located on the emission side from the center of the fine particles.

FIG. 12 is an explanatory diagram showing a trapped state when the focal position f of the laser light is outside the fine particles and is located on the incident side from the center of the fine particles.

FIG. 13 is an explanatory diagram showing a trapped state when the focal position f of the laser light is outside the fine particles and is located on the emission side from the center of the fine particles.

FIG. 14 is a cross-sectional view showing a conventional electrophoretic display element when no voltage is applied.

FIG. 15 is a cross-sectional view showing a state when a voltage is applied, according to a conventional electrophoretic display element.

[Explanation of symbols]

1a and 1b are transparent substrates, 3 is a dispersion system layer, 31 is a dispersion medium,
32 is a colored dispersed particle, 10 is a light control cell, 20 is a laser irradiation means, 21 is a laser oscillator, and 11 and 11 'are lens groups.

Claims (1)

[Claims] 1. A dispersion layer having a dispersion medium and colored dispersion particles dispersed in the dispersion medium and having a higher refractive index than the dispersion medium is disposed between a pair of substrates, at least one of which is transparent. A dimming cell having a lens group in which a plurality of lenses are arranged in a direction parallel to the surface of the transparent substrate on one side of the transparent substrate; And a laser irradiation means for irradiating the light control cell with laser light in a predetermined pattern corresponding to the arrangement of the lens groups.