JP3250689B2 - Optical switching element and optical switching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switching element and an optical switching method for reflecting and deriving light by utilizing a change in the refractive index of a liquid crystal layer.

[0002]

2. Description of the Related Art In recent years, it has been known to change the refractive index of a liquid crystal element as a means for performing light modulation. Among them, for example, a device using a twisted nematic liquid crystal element needs to include a pair of polarizing plates. However, in a system having a polarizing plate, the loss of transmitted light is large, so that it is necessary to perform light modulation in consideration of the loss.

As the light modulating means, for example, there is an optical switching element for changing the transmittance of liquid crystal to obtain a bright and dark binary state of transmitted light intensity. When the optical switching element is used in, for example, a display device, the light amount of the light source must be increased in consideration of the loss of the light amount. In addition, the capacity of the power supply increases with this, so that the power consumption also increases. The increase in power consumption is not preferable because, for example, when it is mounted on a portable computer, the operation compensation time is shortened.

Furthermore, when the optical switching element is used as an exposure shutter, it is necessary to increase the light amount of the light source or extend the exposure time in consideration of the loss of the light amount. In particular, if measures are taken by extending the exposure time, this may cause a decrease in the throughput of a printer or the like.

[0005]

As described above, in an optical system using a polarizing plate, a loss of light quantity cannot be avoided, and it cannot be said that light is efficiently modulated. Therefore, the present invention
The present invention has been made in view of the above circumstances, and has as its object to provide an optical switching element and an optical switching method that can suppress transmission loss of light and increase the contrast ratio between light and dark of emitted light.

[0006]

According to the present invention, there is provided an optical switching device comprising: a liquid crystal layer having an electro-optical effect;
An interface forming means for applying an electric field to the liquid crystal layer to form at least one interface having a different refractive index from an adjacent region; a control means for controlling electric field intensity and electric field application timing of the interface forming means; And a light introducing means for introducing the light, the interfaces are formed so as to reflect the light introduced by the light introducing means to a predetermined position, and the interface is introduced by the light introducing means by controlling the control means. The reflected light is reflected and derived at a required intensity and a required timing.

A liquid crystal layer having an electro-optic effect; and an interface forming means for applying an electric field to the liquid crystal layer to form an interface group consisting of at least one interface having a different refractive index from an adjacent region. Controlling the electric field intensity and electric field application timing of the interface forming means, controlling means for forming an interface having a required reflectance at a required timing, and light introducing means for introducing light to the interface, respectively, Each of the constituent interfaces is formed so as to reflect the light introduced by the light introducing means to a predetermined position, and the control means controls the light so that the light introduced by the light introducing means has a required intensity and a required intensity, respectively. The light is reflected and derived at a timing, and the derived light is sequentially moved.

[0008] An optical switching method according to the present invention comprises:
An electric field is applied to the liquid crystal layer having an electro-optical effect to form at least one interface having a different refractive index from the adjacent region at an arbitrary position, and the intensity, application timing, and application direction of the electric field are controlled to control the interface. Is controlled so that the light is guided to a required position at a required intensity and a required timing.

[0009]

According to the means of the present invention, a liquid crystal is used.
An electric field is applied to a part of the used medium layer to form an interface having a different refractive index from that of the adjacent region, and light is introduced to the interface. The introduced light is reflected at the interface and is derived from the medium layer.
At this time, while controlling the applied intensity of the electric field to change the reflectivity of the interface, changing the intensity of light reflected at the interface, and controlling the timing of applying the electric field, the interface is formed and extinguished, and is introduced into the medium layer. Change the optical path of the light.

When the light emitted from the medium layer is observed when the interface having the required reflectivity is formed and extinguished, the intensity of the light changes. Operation is observed. When a plurality of interfaces are formed, the direction of formation of each interface is controlled so that the light reflected at each interface is emitted at the same position and with emphasis on each other.

A plurality of interfaces are formed so that the light reflected at each interface is emitted to different positions, and the formation and disappearance of each interface are sequentially controlled, so that the light derived from the medium layer is formed. Move sequentially. Examples of the medium layer having the electro-optic effect include various liquid crystal layers. In particular, when a ferroelectric liquid crystal layer is used, an interface can be formed and annihilation response can be made, and high-speed switching operation can be compensated. In addition to the liquid crystal layer, PLZT, PZT,
BaTiO ₃ , LiNiO ₃ , TbTiO ₃ , ZnO or the like can be used.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. FIG.
As shown in FIG. 3, the light modulation element 100 includes a chromium electrode 10 disposed opposite to a pair of glass substrates 101 and 103.
The nematic liquid crystal layer 113 subjected to the parallel alignment treatment by the alignment layers 109 and 111 is sandwiched between the liquid crystal layers 5 and 107. A voltage is applied to the chromium electrodes 105 and 107 at a required intensity and a required timing by a driving unit controlled by a control unit (not shown), and an interface is formed in the electric field application region of the liquid crystal layer 113. At the formed interface, a bird's-eye view 90
The light vertically incident on the glass substrate 101 is reflected at 90 ° by the prism 115 and is introduced.

The operation of the light modulation device will be described below with reference to FIGS. In the figure, (a), (b)
Indicates a side surface and an upper surface of the light modulation element, respectively.
The liquid crystal molecules of the liquid crystal layer 113 constituting the light modulation element 100 are arranged parallel to the glass substrates 101 and 103 when no electric field is applied. When a voltage is applied to the chromium electrodes 105 and 107, the liquid crystal molecules are arranged in parallel to the electric field application direction,
An interface 201 having a different refractive index from an adjacent liquid crystal molecule (adjacent region) is formed. When light enters the interface 201 as illustrated, the light is reflected by the interface 201.

On the other hand, when the voltage applied to the chromium electrodes 105 and 107 is cut off, no electric field is applied to the liquid crystal molecules, whereby the liquid crystal molecules are again arranged in the original state.
Therefore, when the timing of the voltage applied to the chromium electrodes 105 and 107 is controlled and the light emitted from the liquid crystal layer 113 is observed, a switching operation in a bright and dark binary state is observed.

When the intensity of the voltage applied to the chromium electrodes 105 and 107 is controlled, the reflectance of the interface 201 changes. That is, as the voltage intensity increases, the reflectance of the interface 201 increases, and the intensity of light reflected at the interface 201 increases. On the other hand, when the voltage intensity is lowered, the interface 201
Is reduced, and the intensity of light reflected at the interface 201 decreases. Therefore, light of a required intensity is emitted by controlling the voltage intensity.

Although the light incident on the interface 201 is reflected at one boundary surface, the light reflected at the other boundary surface (the dashed line in the figure) may be used. Further, as shown in FIG. 3, a pair of chromium electrodes 301, 303, and 305, 307 are arranged at required intervals, respectively, to form interfaces 309, 311 in the liquid crystal layer 113.

When light enters the interfaces 309 and 311 as shown, the light is reflected by the interfaces 309 and 311 respectively. At this time, the formation directions and phase conditions of the interfaces 309 and 311 are set so that the respective reflected lights are condensed at the same position, and the phases of the respective reflected lights are aligned and the condensed lights are mutually emphasized. I do. The direction in which the interface is formed is set by the direction in which the electric field is applied to the liquid crystal molecules, and the phase condition is set by the optical path length.

By reflecting the incident light at each of the plurality of interfaces having an appropriate optical path length, light having a high contrast ratio between light and dark is emitted from the liquid crystal layer 113. Hereinafter, another switching operation of the light modulation element will be described with reference to FIG. In FIG. 4, (a),
(B) has shown the side surface and the upper surface of the light modulation element, respectively.

The light modulation element 100 shown in FIG. 4 emits light reflected at a plurality of interfaces to different positions. As shown, a pair of chrome electrodes 401,
The interfaces 409, 411 are formed by arranging 403, and 405, 407 at required intervals. Interface 40
The directions in which the light beams 9 and 411 are formed are set so that light reflected at each interface is emitted to a required position.

In this state, the chromium electrodes 401, 403,
, 405 and 407 are alternately switched, whereby the interfaces 409 and 411 are alternately formed and disappear. Therefore, when light emitted from the liquid crystal layer 113 is observed, light emitted to different positions is observed alternately. By further increasing the number of interfaces and controlling the formation and disappearance of each interface, a more complicated switching operation is possible. Also, as shown in FIG.
An interface group consisting of a plurality of interfaces reflecting at the same position may be formed, and the formation and disappearance of each interface group or each interface may be controlled.

In the above-described embodiment, as a means for making light incident, for example, a 90 ° overhead prism which reflects light perpendicularly incident on the glass substrate 101 in a right angle direction and introduces it into the liquid crystal layer 113 can be used. . The thickness of the liquid crystal layer to be sandwiched is 0.01 μm to 10 mm, preferably 0.1 μm to 1 mm, more preferably
Set to 0.5 μm to 100 μm. Further, the refractive index anisotropy of the liquid crystal is preferably 0.1 or more.

According to the embodiment described above, the liquid crystal layer 11
Since the electrode for applying an electric field to the electrode 3 is a chrome electrode, it can be arranged in each minute area.
In Oxide), the durability against ultraviolet rays can be increased. Further, since the sheet resistance is small, the dullness of the signal waveform to be applied is eliminated, thereby enabling a high-speed response of the liquid crystal molecules. In addition, since a polarizing plate is not required, there is no deterioration due to ultraviolet rays, so that the durability of the switching element can be increased.

In the embodiment described above, the case where the electric field is applied to the liquid crystal layer by the fixed electrode has been described. However, in addition to this, for example, a liquid crystal layer may be sandwiched between photoconductive layers whose impedance changes by light irradiation, and the direction of an electric field applied to the liquid crystal layer may be controlled by light irradiation. In this case, the degree of freedom in setting the optical system is increased, and the optical system can be controlled in time series.

[0024]

According to the invention described above, since a polarizing plate is not required, a switching operation having a high contrast ratio between light and dark can be performed. Further, the switching direction (emission direction) can also be set arbitrarily. Further, the switching position of the emitted light can be arbitrarily changed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 2 is a principle diagram for explaining the operation of the optical switching element shown in FIG.

FIG. 3 is a principle diagram for explaining the operation of the optical switching element shown in FIG. 1;

FIG. 4 is a principle diagram for explaining the operation of the optical switching element shown in FIG. 1;

[Explanation of symbols]

Reference Signs List 100 optical switching element 101, 103 glass substrate 105, 107, 301 to 307, 401 to 407 electrode 109, 111 alignment layer 113 liquid crystal layer 115 prism 201, 309, 311, 409, 411 interface

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/13 505 G02F 1/137 G02F 1/31

Claims (4)

(57) [Claims] A liquid crystal layer having an electro-optic effect; an interface forming means for applying an electric field to the liquid crystal layer to form at least one interface having a different refractive index from an adjacent region; And control means for controlling electric field application timing, and light introducing means for introducing light to the interface, wherein the interfaces are formed so as to reflect the light introduced by the light introducing means to predetermined positions, respectively. An optical switching element, wherein the control means controls the control means to reflect and extract the light introduced by the light introducing means at a required intensity and a required timing. 2. A liquid crystal layer having an electro-optic effect, and an interface forming means for applying an electric field to the liquid crystal layer to form an interface group consisting of at least one interface having a different refractive index from an adjacent region. Controlling the electric field intensity and the electric field application timing of the interface forming means to form an interface having a required reflectivity at a required timing; and a light introducing means for introducing light to the interfaces, respectively. Each of the constituent interfaces is formed so as to reflect the light introduced by the light introducing means to a predetermined position, and controls the control means so that the light introduced by the light introducing means has a required intensity and a required intensity, respectively. An optical switching element wherein light is reflected and derived at a timing and the derived light is sequentially moved. 3. The liquid crystal device according to claim 2 , wherein said interface forming means includes an electric field.
A metal electrode to be applied.
Is an optical switching element according to 2. 4. An electric field is applied to a liquid crystal layer having an electro-optic effect.
In addition, at least one field having a different refractive index from the adjacent area
The surface is formed at an arbitrary position, and the strength and application of the electric field
The timing and the direction of application are controlled and introduced to the interface.
The required intensity and tie at the required location.
The optical switch is characterized by
Switching method.