JP2562023B2 - Light modulator - Google Patents

Description

Detailed Description of the Invention a. TECHNICAL FIELD The present invention relates to an optical modulator.

B. Conventional technology Conventionally, as an electro-optical element (light control element) having a so-called electro-optical effect in which birefringence changes with applied voltage, (Pb _1-x , Lax) (Zry, Tiz) _{1-1 / 4} O ₃ An OLZT crystal represented by is known.

This PLZT is a transparent ferroelectric ceramic, and has the property that its birefringence changes depending on the applied voltage based on its electro-optical effect. Between the analyzer and the analyzer), the polarization state changes when the light linearly polarized by the polarizer passes through the PLZT, and only the light component that matches the polarization plane of the analyzer is emitted from the analyzer. Will be done. Such an optical modulation function is used as an optical shutter, but the PLZT shutter has a very fast response speed, the light transmittance ratio is 2000: 1 at on / off time, and has a wide operating temperature range and long life. It has advantages such as

As an optical shutter array using such a PLZT crystal, the one shown in FIG. 11 is conventionally known. According to this, the PLZT crystal 64 is divided into a large number of crystal parts 64a, and the common electrode 66 and the signal electrode 65 are alternately sandwiched between these crystal parts. Part 64a
Will form a set of pixels 76. Therefore, when an electric signal is supplied to the predetermined signal electrode 65, an electric field indicated by an arrow 60 is generated in the crystal of the pixel as shown in the figure, and this electric field modulates the light incident on the pixel and emits the light from the pixel. However, the
In an array like the one in Figure 11, one pixel has two parts 64
Since the structure is divided into a and the signal electrode 65 divides them, the area where the light is modulated is reduced, and the amount of incident light to the pixel (and thus the amount of emitted light) is lost, which results in efficiency. It is difficult to obtain a sufficient amount of emitted light.

An optical shutter array as shown in FIG. 12 is also known. In this case, the PLZT crystal 74 is not divided, and the common electrode 86 and the signal electrode 86 are alternately provided on the front surface and the back surface thereof to form each pixel 96. In the case of this array, an electric field 80 is generated in the crystal 74 as shown, but when there is an uncontrolled pixel next to the pixel that controls light, the electric field 80 behaves as shown for that pixel. As a result, the light may be partially modulated even in the non-operating pixels, and so-called crosstalk is likely to occur. Further, in this array, since the electric field is concentrated on the surface region of the crystal, the optical thickness cannot be sufficiently utilized for the crystal thickness, resulting in insufficient efficiency.

C. OBJECT OF THE INVENTION It is an object of the present invention to provide an optical modulation device that can perform favorable optical modulation (optical control) while advantageously utilizing the electro-optical effect, and that can operate particularly efficiently and without crosstalk.

D. Structure of the Invention That is, the present invention, a crystal element having an electro-optical effect,
In an optical modulator having an electrode provided on this crystal element, the crystal element is divided into a plurality of parts, and the plurality of crystal element parts are integrally coupled to each other via an electrode, and the plurality of crystals are formed. The present invention relates to a light modulation device characterized in that another electrode is provided on each surface of an element portion.

E. Examples Hereinafter, examples of the present invention will be described.

First, an optical shutter as an optical modulator according to this embodiment will be described in detail with reference to FIGS.

As shown in FIG. 4, the optical shutter 6 basically comprises a combination of a light incident side polarizer 33, a PLZT crystal 44, a transparent support substrate 40 of this crystal, and a light emission side analyzer 38. It consists of a laminate. The polarizer 33 is fixed on the substrate 40 with an adhesive 49. The PLZT crystal 44 is divided into a large number of portions 44a, and one pixel 7 is formed for each divided portion 44a. Then, the respective crystal parts 44a are integrally combined with each other through the electrode 36 serving as a common electrode to form a columnar array as a whole. Further, on the upper and lower surfaces of each crystal part 44a, for example, ITO (In
transparent electrodes 35a, 35b are deposited.
These transparent electrodes are connected to each other by the transparent electrode portion 35c on the crystal side surface. And this columnar array 44
When mounted on the transparent substrate 40, the above-mentioned electrodes 35a and 35 with respect to the lead wires 45, 46 previously provided on the substrate 40.
Make sure that b and 36 are connected to each other. In Figure 3,
I showed an example of making such connection with solder 50,
Other methods (for example, wire bonding) may be used.

In each pixel 7, since the birefringence of the PLZT crystal changes according to the voltage between the electrodes 35 and 36, light control can be performed by selecting the voltage, as described later. That is, as shown in FIG. 5, an electric field indicated by an arrow 20 is generated deep enough in the crystal of the pixel 7 by the above voltage, so that the incident light is sufficiently modulated. This is advantageous because the electrodes 35a and 35b are formed on the upper and lower surfaces, and the thickness of the crystal to be modulated (or the optical path length) extends substantially over the thickness d of the crystal, as described later. Further, since the control signal electrodes 35a and 35b are both transparent electrodes, it is possible to obtain a large amount of incident light and a large amount of emitted light, respectively. Therefore, it is possible to obtain a sufficient amount of light as modulated light, which is very effective as exposure light described later. It will be

Further, as understood from FIG. 5, each crystal part 44a
Since the common electrode 36 is interposed between them, the influence of the electric field 20 can be prevented and so-called crosstalk does not occur.

In order to manufacture this optical shutter array, as shown in FIG. 6, the PLZT divided into each pixel is formed.
Electrodes 36, 35a, 35b, and 35c are provided on the crystal 44a, and then these crystal portions 44a are bonded to each other and sintered to form a columnar body. Then, this may be fixed on the substrate 40. Alternatively, each crystal portion 44a is first sintered and then each electrode 3
It is also possible to deposit 6, 35a, 35b, and 35c and then bond the respective crystal parts to form a columnar body, which is fixed to the substrate 40.

In FIG. 1, for example, the width a of the crystal 44a, the width b of the electrode 35a, the space 2l between the electrodes 36-36, and the thickness d of the crystal 44a are preferably in the following dimensional ranges.

1000 ≦ a ≦ 5000 μm 2l / 10 ≦ b ≦ 2l / 5 100 ≦ 2l ≦ 300 μm 300 ≦ d ≦ 1000 μm In FIG. 7, the element shown in FIGS. 1 to 5 is shown in principle. The following equation holds for the optical shutter array.

(I: outgoing light amount, I _o : incident light amount, π: circular constant, λ: wavelength of used light, Γ: retardation) Therefore, I changes depending on the value of Γ, Then, I = I _o , which is the maximum. Γ can be written as follows.

Γ = Δn · t (Δn: birefringence, t: optical path length) = (−n ³ RE ^a / 2) · t (R: electro-optic coefficient, n: refractive index of material, E: electric field, a: depending on material determined real number 1 or ^{2) = (- n 3 RV} a / 2l a) · t (V: applied electric field, l: distance between electrodes) that, gamma is changed by V, I is changed becomes accompanied thereto .

I becomes the maximum at V when V becomes, and this V is called a half-wave voltage.

FIG. 8 to FIG. 10 explain the usage state of the optical shutter array 6 described above.

First, the main part of the color image recording apparatus will be described with reference to FIG. According to this device, the white light source 1 and the photosensitive material 2
A slit plate 3 with a slit 4 and a PLZT optical shutter array 6 in which a large number of pixels (pixels) 7 are arranged are sequentially arranged between and. The array 6 is a simplified illustration of the array shown in FIGS. The slit light 5 that has passed through the slit plate 3 enters the optical shutter array 6, is optically modulated as described above, and then exits to be used for exposure of the photoconductor 2. The optical shutter array 6 receives the image signal 8
The optical shutter is made to function by the drive voltage from the control unit (or drive unit) 9 that receives and operates.
The control unit 9 also gives a signal to the drive motor 10 of the photoconductor 2 to control the rotation thereof.

The image signal 8 input to the control unit 9 is obtained, for example, as shown in FIG. That is, the original 11 is illuminated and the image portion 12 is illuminated.
The reflected light 13 from is incident on the CCD 15 which is a charge-coupled device through the imaging lens 14, and the electric signal of this CCD is controlled by the control unit 9.
To enter. The controller 9 also controls the movement 16 of the optical unit with respect to the original 11.

FIG. 10 shows an example of a color image recording apparatus incorporating the above optical shutter array 6 (however, the control unit 9 is not shown). In this apparatus, instead of the photoconductor 2 shown in FIG. 8, a belt-shaped photoconductor 2 which is moved from the rolled state along the peripheral surface of the guide roller 17 is used. A photographic paper coated with a photographic emulsion is used as the photoconductor 2, and the optical shutter array 6 sequentially performs the exposure for each color as described with reference to FIG. 23 is a lens). Next, the photographic printing paper 2 includes a color developing section 28, a bleach-fixing section 29, and a stabilizing section.
After passing through 30, 31, and 52 in sequence, it is sent to the drying section 53 and taken out as a color print. (Note that 54 in the figure is a replenisher).

In such a device, the optical shutter array 6 is driven to function as an optical shutter by a control voltage corresponding to each color (blue, green or red) from the control unit 9.

Although the present invention has been illustrated above, the above-described example can be further modified based on the technical idea of the present invention.

For example, the electrode portion 35c described above can be omitted, but in this case, the electrode 35a can be connected to the lead wire 45 by wire bonding, and the electrode 35b can be flip-chip type.

Also, the shape of the electrodes and the connection method can be variously changed. PLZT
The shape, size, size, etc. of the crystal may be variously changed. In addition, as a photoconductor, Se-T used in electrophotography
Photosensitive materials such as e and phthalocyanine can also be used, and a color image can be formed by a known electrophotographic method. Also,
The present invention may be applied not only to full color but also to monochrome image formation such as mono color. Also for the optical shutter array,
The configuration, structure, material, etc. may be changed. The recording method may be variously changed, and for example, the development may be performed in a non-contact manner or a magnetic brush method. The developer used may be either a two-component or one-component developer.

F. As described above, the present invention has a structure in which a crystal element having an electro-optical effect is divided into a plurality of pieces, each of which is integrated through an electrode and another electrode is provided on the surface of the crystal element. Utilizing the effect, light modulation is advantageously exerted, a sufficient electric field for modulation is generated in the thickness direction of the crystal, and the pixels are cut off to prevent crosstalk.

[Brief description of drawings]

1 is a perspective view of an electro-optical element (optical element) made of PLZT crystal, FIG. 2 is an enlarged sectional view taken along line II-II of FIG. 1, and FIG. 3 is an enlarged sectional view taken along the line III-III in FIG. 1, FIG. 4 is a sectional view similar to FIG. 2 including the upper and lower polarizers and the analyzer in FIG. 1, and FIG. 5 illustrates optical modulation. 2 is a cross-sectional view similar to FIG. 2 (however, there is a part where cross-section hatching is omitted), FIG. 6 is an exploded perspective view when assembling the optical modulator, and FIG. 7 is a diagram illustrating the principle of the optical shutter. FIG. 8 is a schematic perspective view of an essential part of the image recording apparatus, FIG. 9 is a schematic view of one system for obtaining an image signal, and FIG. 10 is a schematic sectional view of the entire image recording apparatus. FIG. 11 and FIG. 12 are enlarged cross-sectional views showing two examples of conventional light modulators (however, there are some parts where cross-section hatching is omitted).
Is. In the reference numerals shown in the drawings, 1 ... Light source 2 ... Photoconductor 3 ... Slit plate 6 ... Optical shutter array 7 ... Pixel (pixel) 9 ... Control unit (driving unit) 33 ... Polarizer 35a , 35b ...... Electrode 36 ...... Common electrode 38 ...... Analyzer 40 ...... Transparent substrate 44, 44a ...... PLZT crystal (part) 45, 46 ...... Lead wire.

Claims (1)

(57) [Claims] 1. A light modulator having a crystal element having an electro-optical effect and an electrode provided on the crystal element, wherein the crystal element is divided into a plurality of portions, and the plurality of crystal element portions are provided with electrodes interposed therebetween. Are integrally coupled to each other, and another electrode is provided on each surface of the plurality of crystal element portions.