JPS60120330A - Optical modulating element - Google Patents

Abstract

PURPOSE:To perform modulation with good S/N by providing a medium which causes a physical change by contacting closely one of reflecting films of two reflecting surfaces arranged at some angle and a medium which causes a physical change at least one place on the other surface. CONSTITUTION:Insulating layers 21a and 21b provided with heating resistors 22a and 22b, metallic reflecting films 23a and 23b, heat-effect media 24a and 24b, and transparent protection films 25a and 25b are laminated to constitute optical modulation parts 30a and 30b which are controllable independently of each other. The modulation parts 30a and 30b are supported on a support base 20 at an angle theta. Incident light 32 shown by an arrow is reflected twice by the surfaces 23b and 23a when not modulated to obtain projection light 33, and the angle phi between the light 32 and light 33 is 2theta. When at least one of the heating bodies 22a and 22b is heated, the heat-effect media vary in refractive index corresponding to the heating part and the projection light 33 changes the direction. Consequently, unmodulated light and modulated light are separated easily to improve the S/N. The physical change is made by utilizing electric field application, the generation of air bubbles, etc., in addition to the heating.

Description

[Detailed description of the invention] Related to modulation elements.

2. Description of the Related Art Conventionally, recording or displaying using a luminous flux has been widely practiced. A typical example of this is a laser beam printer, which uses a mechanical deflector to deflect a beam of light, modulates the beam, and records information on a photosensitive drum. On the other hand, in recent years, it has been proposed to locally generate a physical change and modulate the luminous flux by this physical change.

For example, Japanese Patent Laid-Open No. 56-5523 discloses that an electric field is locally applied to a crystal made of an electro-optic material, and the refractive index of the portion to which the electric field is applied is changed to perform optical modulation. In addition, the patent application filed by the applicant in 1985-1285
No. 66 describes a method of modulating the luminous flux by locally generating vapor bubbles in a liquid, and Japanese Patent Application No. 1, 1982, 792-65 describes a method of modulating a luminous flux by locally generating vapor bubbles in a liquid. A method of modulating the light flux by generating a refractive index profile is shown.

The above modulation methods all use a light modulation element that can modulate the incident light flux within a certain period of time by applying a modulation signal pulse. Of this light modulation element, patent application 1977
- ], Figure 1 shows what is shown in No. 79265.
Shown in Figure 2. In FIG. 1, 1 is a transparent protective plate, 2 is a thermal effect medium layer whose refractive index distribution changes with heat, and is a liquid or solid thin layer, 3 is a thermally conductive insulating layer, and 4 is 5a.
A heating resistor layer 16b, 5c, 5a, . . . in which heating resistors are arranged, 5 is a support for the insulating layer 3 and the heating resistors 6a16h, 6c16d, . When the heating resistor generates heat, this heat is transmitted through the insulating layer 3 to the thin thermal effect medium layer 2, creating a temperature distribution within the thin layer and forming a refractive index distribution. For example, as shown in FIG. 1, when the heat-generating resistor 6b is selected and generates heat, this heat is transmitted to the thin heat effect medium layer 2 via the insulating layer 3 adjacent to the resistor 6b, and the heat is transferred to the resistor 6b. The liquid in the opposing region of the thin thermal effect medium layer 2 is heated to form a refractive index distribution 7 in this region. This refractive index distribution 7 disappears after a predetermined period of time as this region cools. One cycle from the formation of the refractive index distribution to its extinction is a very short time and can be performed on the order of KHz. The heating resistor has the following characteristics: 1. It is formed on the support body 5 by the manufacturing technique of C, and the interval between adjacent heating resistors is formed on the order of μm.

As the thermal effect medium used in this light modulation element, liquids such as water, alcohol, liquid crystal, and others may be used. The refractive index temperature dependence T of this liquid is -1, OX IF' for water, and -4, OX 10''-' for ethyl alcohol. It is also possible to use the refractive index change during phase change in the liquid phase.However, in this case, consideration must be given to the alignment direction of the liquid crystal and the polarization direction of the incident light.Also, as a solid, acrylic, It is possible to use plastic materials such as polycarbonate, or polymeric materials such as epoxy resins used as adhesives.The n refractive index temperature dependence 1f of these media is approximately -1 in the case of acrylic. ,0
X10--approximately -13 x lO for polycarbonate.

FIG. 2 is a schematic perspective view showing the configuration of the light modulation element shown in FIG. 1, and numbered 1 to 6 are the same as shown in FIG. 1. Reference numeral 8 denotes a conductive wire, which is connected to each drive voltage so that each of the three heating resistors (6a16b...) can be driven independently, while the other end of the heating resistor is installed or connected to a common voltage is set.

From the conductive wire 8, the heating resistors 6a, 6b, etc.
When each mold pressure signal is applied to . When the voltage signal is reduced to zero, this refractive index distribution is cooled down and returns to its original state without refractive index distribution.

FIG. 3(A) shows the light modulation element based on the refractive index distribution, M
FIG. 2 is a diagram showing an example of a light modulation device using a light modulator, in which a light beam whose wavefront of refractive index distribution is modified is used as information light. When the light beam 10 is incident on the light modulation element M, and any heating resistor 6C among the heating resistors (6a, 6b1, . . .) is driven by the voltage Vi,
A refractive index distribution 7 is generated, and the light beam incident on the heating resistor 6C becomes a light beam 12 with a deformed wavefront and exits. A light beam 11 that is specularly reflected on the surface of the heating resistor and whose wavefront is not modified by the refractive index distribution 7 is imaged by a lens 13a, and is blocked by a light-blocking filter 15a disposed at the imaging position.

4- The light beam 12 whose wavefront has been deformed passes through its light-blocking filter.
Although the light is partially blocked by the light blocking filter 158,
Most of the wavefront-converted light beam 12' is irradiated onto the light-receiving medium 14 by setting the size of the light beam 5a to the minimum size that blocks the imaging spot of the light beam 11 whose wavefront is not deformed.

FIG. 3(B) shows the light modulation element based on the refractive index distribution, M
It is a figure which shows the further Example of the optical modulation device using this.

In FIG. 3(B), the light beam whose wavefront has been deformed due to the refractive index distribution is blocked by the light-shielding filter 15b having a partially aperture, and the light beam 11 whose wavefront is not deformed is directed onto the light-receiving medium 14. An example is shown in which the light is irradiated and used as information light.

However, in the optical modulation devices shown in FIGS. 3(A) and 3(B), since the modulated light beam and the non-modulated light beam travel in almost the same direction, there is a drawback that the signal light amount S/N on the light receiving medium is reduced. has.

An object of the present invention is to provide a light modulation element that can prevent the above-mentioned S/N reduction and form a high-quality image by devising the structure of the light modulation element.

Still another object of the present invention is to provide a light modulation method capable of modulating light corresponding to the smallest segment constituting information such as an image, by controlling the amount of light reaching each segment. An object of the present invention is to provide a light modulation element that can be formed.

A feature of the present invention is that a plurality of reflective surfaces are configured in the light modulation element, and when the light beam is not modulated, the light beam incident on the medium is reflected from the plurality of reflective surfaces and then directed in a direction determined by the angle at which the reflective surface is set. On the other hand, during modulation when a physical change occurs in the medium, by using a light component emitted in a direction different from the direction in which the non-modulated light flux is emitted as a modulated light flux,
The purpose is to improve S/N.

The physical change referred to here generally includes a change in refractive index due to heat, but if the medium is a liquid, other possibilities include the formation of bubbles in the medium due to heating, and a change in refractive index due to applying an electric field to the medium.

In the examples described later, a change in refractive index due to heating will be explained as an example.

As a further feature, the means for causing a physical change in the medium includes a plurality of independently controllable means, and selectively operating the plurality of means causes a physical change to occur in the medium. The point is that the amount of light of the modulated light beam can be made variable by making it possible to control the amount of variation in striking.

Hereinafter, when describing the present invention in detail, the above-mentioned type of light modulation element that generates a refractive index distribution and modulates light will be shown as an example, but it goes without saying that the present invention is not limited to such a type However, the present invention is not limited to the above-mentioned type shown in Japanese Patent Application Laid-Open No. 56-5523, the type shown in Japanese Patent Application No. 57-128566, and can be applied to various other types of light modulation elements.

Next, the present invention will be explained based on examples and with reference to the drawings.

FIGS. 4(A), 4(B), and 4(C) schematically show three different embodiments of the present invention in cross-sectional views. In the embodiment of FIG. 4(A), heating resistors 22a and 22b are provided, layers 21a and 21b made of an insulating material, reflective films 23a and 23b made of a metal reflective film or a dielectric multilayer film, and a thermal effect medium 24a, 24h, 'It bright protective layer 25a, 25b
The light modulating parts 30a and 30b are stacked on top of each other in a layered manner to form two independently controllable light modulating parts 30a and 30b. The two light modulators 30a and 30b form an angle θ with each other and are attached to the support base 2.
Supported by 0. These two light modulation sections 30a and 30b function together as one light modulation element.

When the incident light beam 32 in the plane of the paper is not subjected to a modulation effect, it is sequentially reflected by the two reflective surfaces 23b and 23a, and becomes an output light beam 33. The angle ψ formed by the incident light beam 32 and the output light beam 33 is the angle formed by the reflective surfaces 23a and 23b of the two plates.
When ψ=2θ (For example, if θ is 90°, ψ is 180° (
parallel). ) to decide at will.

On the other hand, if less than one of the heating resistors 22a and 122b generates heat due to the modulation signal, the corresponding thermal effect medium 24
．． a, 24. A refractive index distribution occurs within b, and as a result, the modulated light flux has a spread in a direction different from the direction in which the non-modulated light flux 33 is emitted. Therefore, the modulated light flux and the non-modulated light flux are separated through a projection optical system (not shown), etc. 8- becomes possible. Furthermore, a plurality of heating resistors 22a, 22
By selectively heating b, the amount of modulated light flux can be made variable.

In the embodiment of FIG. 4(B), the heating resistor 22a1
Insulating material layers 21a and 21b provided with 22b, reflective film 2
Two light modulating parts 30a' and 30b', each of which has layers 3a and 23b stacked on top of each other, are supported at no angle on the support substrate 20, and the thermal effect medium 24 is formed by the light modulating parts 30a' and 30b'.
30b' and the transparent protection plate disposed above. Therefore, a feature is that each light modulating section 30a', 30b' shares the thermal effect medium 24 and the transparent protective layer 25, and the structure is simpler than that of the embodiment shown in FIG. 4(A).

The embodiment shown in FIG. 4(C) is an element with a simpler configuration, in which the reflective films 23a and 23b are supported at an angle on a support base 20, and a heating element 22 is provided on the upper part. Layer 21 and transparent protective layer 25 are arranged one on top of the other, and reflective film 23a is formed.
, 23b and the layer 21 are filled with a thermal effect medium 24.

These figures 4(B) and 4(C) are also shown in figure 4(B) and 4(C).
It functions almost the same as A).

FIG. 5 is a schematic diagram showing still another embodiment of the present invention. In this figure, the optical modulators 3oa and 30b.

30c constitutes a light modulation element 31 in which they are arranged orthogonally to each other. When the incident light flux 32 enters the light modulation element 31, unless a signal voltage is applied to the heating resistor (not shown) included in each light modulation section 30a, 30b, 300, each light modulation section Since no refractive index distribution occurs in the thermal effect medium (not shown), the incident light beam 32 is specularly reflected by the metal reflective layer (not shown) of each light modulating section 30a, 30b, 130c. Therefore, each light modulation section 30a, 30b.

As a result of the characteristic configuration of this embodiment in which the light beams 30C are arranged so as to be orthogonal to each other, the incident light beam 32 repeatedly undergoes regular reflection at each light modulation section, and then forms a corner cube as an unmodulated light beam 33 on which no signal is carried. According to the principle of , it moves in the opposite direction to the direction of incidence. On the other hand, three light modulation units 30a, 30b,
30c, when a signal voltage is applied to a heating resistor (not shown) in at least one of the light modulating parts, the heat generated by the heating resistor causes a heat effect medium in the vicinity of the heating resistor to be heated. Produces a refractive index distribution. Therefore, when the incident light beam 32 passes through the refractive index distribution due to the thermal effect, it is locally subjected to various refraction effects, and as a result, the modulated light beam 34 carries a signal and the unmodulated light beam 33 carries no signal. produces a component that goes in a different direction than the As described above, when the signal voltage is turned on/off to the heating resistor, the modulated light flux and unmodulated light flux (output light flux) from the light modulation element 34
．． The principle of the present invention is to perform optical modulation by utilizing the difference in the direction in which the light beams move.

Therefore, it is possible to make the direction of the modulated light beam significantly different from the direction of the non-modulated light beam, and as a result, the S/N of the signal light can be significantly improved.

Furthermore, in FIG.
0a, 30b, and 30c can be independently controlled by a drive circuit 35. As a result, by selecting the light modulators 30a, 130b, 30C to be driven 1 in accordance with the modulation signal and applying a signal voltage to the incident light beam 32 (including applying a signal voltage to two or more light modulators simultaneously). It becomes possible to vary the degree of light modulation effect provided, and in turn, it becomes possible to vary the amount of light of the modulated light beam 34 carrying the signal, thereby making it possible to obtain a halftone image.

A person skilled in the art can easily control the operation of the light modulation units 30a, 30b, and 300 independently, so a description thereof will be omitted here.

The above-mentioned light modulation elements can be used by arranging a plurality of them in a one-dimensional array or in a two-dimensional matrix.

FIG. 6 (2) shows an embodiment of a light modulation device to which the light modulation element according to the present invention is applied.

Luminous flux 41 incident on the light modulation element play 50 according to the present invention
may be a sheet-like parallel light beam.

Alternatively, a cylindrical lens (not shown) may form a light beam that forms a linear image near the light modulation element array 50 so as to have a length in the direction in which the element plays are arranged. 51
a151b1..., 51e, 52a, 52b.

..., 52e is a light modulation section according to the present invention, and (5], a, 52a), (stb, 52) of this light modulation section
b) and -1 (51e, 52e) constitute one optical modulation element as a pair. When no modulation signal is applied, the incident light beam 41 is transmitted to the end surface 5 of the optical modulation element array]
, 52 side, and is specularly reflected by a reflecting surface (not shown) provided on each side, and then exits as a non-modulated light beam 42.

The angle formed by the incident light beam 41 and the unmodulated light beam (outgoing light beam) 42 is uniquely determined by the angle formed by the end surfaces 5 and 52 of the light modulation element array. On the other hand, for example (51c.

When a modulation signal is applied to the light modulation element shown in 52C), the incident light beam 41 is modulated based on the above-mentioned modulation principle of the light modulation element, and is emitted in a direction different from the output direction of the unmodulated light beam 42. Modulated light flux 43 which is a traveling light flux component
has. Therefore, it is possible to image the modulated light beam 43 onto the light receiving surface 45 by the optical system 44.

As explained above, by having a plurality of reflective surfaces, the light modulation element of the present invention can emit a non-modulated light beam and a modulated light beam in different directions, and therefore can emit a modulated light beam with good S/H. It has the characteristic of making the amount of modulated light beam variable.

[Brief explanation of drawings]

Figures 1 and 2 are a partial cross-sectional view and a perspective view, respectively, of an optical modulation element that utilizes changes in refractive index due to heat, and Figure 3 (
A), (B) are cross-sectional views of a light modulation device using a conventional light modulation element, and FIGS. 4 (A), (B), and (C) are cross-sectional views of three embodiments of the present invention, respectively. FIG. 5 is a perspective view of another embodiment of the present invention, and FIG. 6 is a perspective view of an embodiment of a light modulation device using the present invention. 21.21a, 21b... Layers of insulating material 22.22a, 22b... Heat generating resistors 23.23a, 23b... Metal Reflective films 24.24a, 24b...Thermal effect media 25.25a, 25b...Transparent protective layers 30a, 30b... ...
...Light modulation section patent applicant Canon Co., Ltd. 15-

Claims (2)

[Claims] (1) A plurality of reflective films having reflective surfaces arranged at angles to each other, a medium that causes a physical change in close proximity to one surface of each of the plurality of reflective films, and the other of the plurality of reflective films. 1. A light modulation element, comprising means for causing a physical change in the medium attached to at least one location on the surface of the medium. (2) The means for causing the physical change is comprised of a plurality of independently controllable means, and the amount of physical change occurring in the medium can be controlled by selectively operating the plurality of means. A light modulation element according to claim 1, characterized in that: