JP2002365604A - Optical shutter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical shutter device in which a half wavelength voltage (a driving voltage) is made low and cross talk is suppressed at a low level. SOLUTION: The optical shutter device is provided with optical shutter arrays. In the arrays, at least two columns of optical shutter elements 41 are arranged on optical shutter chips 12 made by PLZT and a plurality of chips 12 is placed in parallel and in a linear manner. The side of each chip 12 that contacts with other chips 12 is defined as a tilted side 12a having an angle θ. Common electrodes 42 are arranged in a practically parallel manner with respect to an arrangement direction X of the elements 41 and individual electrodes 43 are arranged in a practically parallel manner with respect to the sides 12a. Moreover, a direction M of the electric field applied to the elements 41 from the common electrodes 42 and the individual electrodes 43 is practically made parallel with respect to the sides 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical shutter device,
In particular, the present invention relates to an optical shutter device in which opposing electrodes are provided on a substrate made of a material having an electro-optical effect and a plurality of optical shutter elements are formed in rows.

[0002]

2. Description of the Related Art Conventionally, an external optical modulator for large-capacity optical communication, an optical path switching switch in an optical pulse tester, or an optical signal generating device of an optical printer has been made of a material having an electro-optical effect, such as PLZT and LiNbO. An optical shutter device that has a plurality of optical shutter elements formed on a substrate made of ₃ and has an optical shutter array in which the plurality of substrates are linearly arranged, and controls on / off of light is used.

[0003] Specifically, as shown in FIG.
A pair of electrodes 3 provided on a substrate (optical shutter chip) 30
By applying a voltage to 2, 33 to generate an electric field, P
Bipolar refraction is caused in LZT, and the polarizer 35 arranged at the front stage
The light incident on the optical shutter element (light modulation area) 31 through the light is polarized by 90 °, and the emitted light passes through the analyzer 36. On the other hand, when no electric field is generated, the light that has passed through the polarizer 35 passes through the optical shutter element 31 without being polarized, and is blocked by the analyzer 36.

In such an optical shutter element 31, the maximum amount of transmitted light can be obtained when the incident light is polarized by 90 °, and the applied voltage at this time is called a half-wave voltage, which is usually a half-wave voltage. The element 31 is driven by the voltage.

FIG. 8 shows an electrode pattern for an optical shutter element improved by the present inventors. A common electrode 32 grounded to the ground and an individual electrode 33 facing the common electrode 32 are formed on the chip 30, and an optical shutter element 31 (a hatched portion in FIG. 8) is provided between the electrodes 32, 33.
It has been.

When the arrow X is the main scanning direction and the arrow Y is the sub-scanning direction, the optical shutter elements 31 are arranged in two rows in a zigzag pattern. Have been.

For example, when the optical shutter array is used for forming an image, the optical shutter elements 31 are driven one row at a time in synchronization with the movement of the recording medium with respect to the recording medium moving in the Y direction. Exposure is performed one line at a time in the X direction without any gaps to form a two-dimensional image. In the electrode pattern shown in FIG. 8, since an electric field is applied to the PLZT even in a region other than the optical shutter element 31, light leaks.
A light-blocking layer having a window defining a light-transmitting opening is provided.

As described above, when used for forming an image, thousands of optical shutter elements 31 are required to expose about 30 cm in the main scanning direction indicated by the arrow X. It is difficult to realize this with one chip 30, and chips 30 on which several hundred elements 31 are formed are arranged side by side in the arrow X direction to form an array. At this time, even if a plurality of chips 30 are used, the chips 30 are formed in a parallelogram shape in which both end surfaces are inclined so that the optical shutter elements 31 are juxtaposed in the X direction without a gap. Therefore, the individual electrodes 33 are wired in parallel with the inclined side 30a.

[0009]

The chip 30 having a planar electrode structure shown in FIG. 8 has a simpler process than a chip having a three-dimensional electrode structure in which a chip is formed three-dimensionally and electrodes are provided in a three-dimensional part. And can be manufactured at low cost. However, a major problem is that the half-wave voltage (drive voltage) is high. If the driving voltage is high, a high-withstand voltage IC must be used, resulting in an increase in cost, an increase in power consumption, and an adverse effect such as a malfunction due to electric noise.

In addition, crosstalk between adjacent optical shutters is likely to occur, and depending on the operation pattern of each optical shutter element (for example, whether the individual elements are turned on or the adjacent elements are turned on at the same time), each optical shutter element is turned on. Has a problem that the amount of transmitted light changes.

In particular, the optical shutter chip 30 shown in FIG.
, The individual electrodes 33 are wired obliquely with respect to the direction M of the electric field, and have a parallelogram shape. Therefore, the electric field from each individual electrode 33 to the common electrode 32 is not effectively applied to the optical shutter element 31, so that the half-wave voltage becomes higher, and the crosstalk increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical shutter device having a low half-wave voltage (driving voltage) and capable of suppressing crosstalk.

[0013]

In order to achieve the above objects, an optical shutter device according to the present invention comprises a substrate made of a material having an electro-optical effect, and a plurality of opposing common electrodes and individual electrodes provided on a substrate. At least two optical shutter elements
In an optical shutter device having an optical shutter array in which a plurality of substrates are arranged in a line and a plurality of substrates are linearly juxtaposed in parallel to the arrangement direction of the optical shutter elements, each substrate has an optical shutter element having a side in contact with another adjacent substrate. The common electrode is wired substantially parallel to the array direction of the light shutter elements, and the individual electrodes are wired substantially parallel to the inclined side of the substrate. The direction of the electric field applied to the optical shutter element from the common electrode and the individual electrode is substantially parallel to the inclined side of the substrate.

In the optical shutter device according to the present invention, the side of each substrate which is in contact with another adjacent substrate is an inclined side. Optical signal can be generated. Since the direction of the electric field applied to the optical shutter element from the common electrode and the individual electrode is substantially parallel to the inclined side of the substrate, the electric field is efficiently applied to each optical shutter element, and the half-wavelength is applied. The voltage is reduced, driving can be performed at a low voltage, and crosstalk is reduced.

In particular, in the optical shutter device according to the present invention, the inclination angle θ of the inclined side of the substrate is preferably 45 ° ≦ θ <90 °. When the inclination angle θ is 45 ° or less, corners of the substrate are easily chipped.

If the distance between the common electrode and the individual electrode is L, the distance G between each row of the optical shutter elements is G ≧ 1.5.
L is preferred. This is for ensuring the required width of the common electrode. Further, if the dimension in the direction orthogonal to the electric field of either the common electrode or the individual electrode is W, W /
It is preferable that L> 2. Crosstalk between adjacent optical shutter elements can be suppressed to a level that does not cause a practical problem. Further, if the dimension in the same direction as the electric field of either the common electrode or the individual electrode is D, D / L>
It is preferably 0.5, and the half-wave voltage can be kept low.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical shutter device according to the present invention will be described below with reference to the accompanying drawings.

(Overall configuration of optical shutter device, see FIG. 1)
First, FIG. 1 shows the overall configuration of an optical shutter device according to the present invention. This optical shutter device is configured as a full-color image writing head for a recording medium (photographic paper), and includes a light source (halogen lamp) 1, a heat insulating filter 2,
Color filter 3, optical fiber array 4, polarizer 5
, An optical shutter module 6, an analyzer 7, and an imaging lens array 8.

The color filter 3 has three primary colors of light, R,
This is a disk-shaped rotator having three filter portions for transmitting G and B, and is driven to rotate in synchronization with writing of one line by an optical shutter element described below. The optical fiber array 4 is a bundle of a large number of optical fibers alone, and the light emitted from the light source 1 irradiates the incident end 4a via the heat insulating filter 2 and exits straight from the other end 4b.
The polarizer 5 and the analyzer 7 are arranged in crossed Nicols, and
They are arranged so that each polarization plane is at 45 ° to the direction of the electric field applied to the optical shutter element.

The optical shutter module 6 includes a ceramic or glass substrate 11 having a slit-like opening.
An array is formed by arranging a plurality of optical shutter chips 12 made of PLZT thereon, and driving circuits 13 are arranged on both sides of the chips 12. Each optical shutter chip 12 has a large number of light beams corresponding to one pixel. A shutter element is formed. As shown in FIG. 2, the optical shutter elements 41 are arranged in two rows, and each element 41 is formed in a zigzag pattern by one pixel.
One line of an image is formed in the main scanning direction X in a row.

As is well known, PLZT is a translucent ceramic having a large Kerr constant and having an electro-optical effect, and the light linearly polarized by the polarizer 5 is a voltage applied to the optical shutter element 41. When turned on, the polarization plane is rotated, and the light is emitted from the analyzer 7. When the voltage is off, the polarization plane does not rotate, and such transmitted light is cut by the analyzer 7.

That is, the on / off of the transmitted light occurs when the voltage to each optical shutter element 41 is turned on / off, and the light emitted from the analyzer 7 passes through the imaging lens array 8 onto a recording medium (not shown). Form an image. The optical shutter element 41 is turned on / off line by line based on image data (main scanning), and the main scanning and the movement of the recording medium in the Y direction (sub-scanning) form a two-dimensional image on the recording medium. Is formed.

FIG. 2 shows a main part of a first embodiment of the present invention. FIG. 8 shows that the common electrode 42 and the individual electrode 43 are formed on the optical shutter chip 12 made of PLZT, and the area where the electrodes 42 and 43 face each other is an optical shutter element 41 (shown by oblique lines). This is the same as the optical shutter chip 30 shown.

That is, the optical shutter element 41
Are arranged in a zigzag pattern in two rows at intervals of
Are arranged in a straight line parallel to the arrangement direction X of the optical shutter elements 41, and the optical shutter elements 41 are arranged without gaps in the X direction by overlapping in the Y direction.

Each chip 12 has an inclined side 12a whose side in contact with another adjacent chip 12 is inclined at a predetermined angle θ with respect to the arrangement direction X. The common electrode 42 is wired substantially parallel to the arrangement direction X of the light shutter elements 41, and the individual electrode 43 is wired substantially parallel to the inclined side 12a. The direction M of the electric field applied to each optical shutter element 41 from the common electrode 42 and the individual electrode 43 is substantially parallel to the inclined side 12a.

In the first embodiment, the optical shutter elements 41 have a pitch of 63.5 μm, that is, 2P = 127 μm.
Are arranged in the X direction, and the column interval G = 317.5 μ
m, the inclination angle θ of the inclined side 12a is 79 °. Each optical shutter element 4 is provided between the individual electrode 43 and the common electrode 42.
The direction M of the electric field acting on 1 is parallel to the wiring direction of the individual electrode 43 (that is, the inclined side 12a).

According to the experiments of the present inventors, the common electrode 42
The distance L between the facing portions of the individual electrodes 43 and
By setting the ratio W / L to the width W to a value exceeding 2, the influence of the electric field from the adjacent optical shutter element 41 on the chip 12 is reduced, and the crosstalk is reduced to a level that does not cause a practical problem. It became clear what we could do.

The dimension D of the individual electrode 43 in the electric field direction M
It has been clarified that by setting the ratio D / L to the distance L to a value larger than 0.5, the half-wave voltage can be kept low and the drive voltage can be reduced.

FIG. 3 shows that the electrode patterns of the present invention example (see FIG. 2) and the comparative example (see FIG. 8) have W
When the value of / L is continuously changed, the ratio of the transmitted light amount when all the elements are turned on and when the elements are turned on alone, that is, the change characteristic of the transmitted light amount due to crosstalk is shown. . The example of the present invention shows better characteristics than the comparative example. In the example of the present invention, if W / L exceeds 2, even if it is a single light, a light amount of 90% or more of the full light can be obtained.

FIG. 4 shows the electrode patterns of the present invention example (see FIG. 2) and the comparative example (see FIG. 8).
5 shows a change characteristic of a half-wavelength voltage when the value of / L is continuously changed. The half-wave voltage of the example of the present invention is lower than that of the comparative example as a whole, and in the example of the present invention, if D / L exceeds 0.5, it is possible to secure a sufficient amount of light at about 140 V and drive. is there.

The electrode pattern shown in FIG. 2 is obtained by making the common electrode 42 sufficiently large. In the optical shutter element 41, there is no essential difference whether any of the pair of electrodes facing each other is a common electrode or an individual electrode.
The condition of / L is valid even if W and D are numerical values related to the common electrode.

Here, considering the end surface inclination angle θ of the chip 12, the inclination angle θ is set to 90 ° in order to arrange the plurality of chips 12 in a straight line and maintain the continuity of each optical shutter element 41 in the X direction. Must be small. On the other hand, if the inclination angle θ is too small, the corners of the chip become acute and chipping easily occurs, and it is preferable that the inclination angle θ is about 45 ° or more.

The distance G between the optical shutter elements 41 is preferably 1.5 L or more in order to secure the width of the common electrode 42 in the Y direction. However, if the interval G is too large, the element rows are separated from each other, and the light use efficiency of the light source unit is reduced. At this point, the interval G is 1000 μm
It is preferable that it is not more than about.

FIG. 5 shows a main part of a second embodiment of the present invention. This optical shutter chip 12 has four rows of optical shutter elements 41 arranged in the X direction, and the other configuration is the same as that of the first embodiment shown in FIG. Therefore, in FIG. 5, the same members and portions as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The operation and effect are the same as those of the first embodiment.

FIG. 6 shows a main part of a third embodiment of the present invention. In this optical shutter chip 12, a common electrode 42 is extended between the respective optical shutter elements 41 to form a shield electrode 42a, and a tip portion of the shield electrode 42a is used as a bonding pad 42b. In the third embodiment, the adjacent optical shutter element 41
Since the ground potential shield electrode 42a is interposed therebetween, crosstalk between the optical shutter elements 41 can be further reduced.

In the third embodiment, the other structure is the same as that of the first embodiment shown in FIG. 2. In FIG. 6, the same members and portions as those in FIG. The operation and effect are the same as those of the first embodiment.

(Other Embodiments) The optical shutter device according to the present invention is not limited to the above embodiments, but
Various changes can be made within the scope of the gist.

For example, a more detailed configuration of the optical shutter chip and a more detailed shape of the common electrode and the individual electrode are arbitrary. The material having an electro-optic effect is the above-mentioned PLZT.
In addition, various things can be used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall configuration of an optical shutter device according to the present invention.

FIG. 2 is a plan view showing a main part of the first embodiment.

FIG. 3 is a graph showing a relationship between W / L and a light amount ratio.

FIG. 4 is a graph showing the relationship between D / L and half-wave voltage.

FIG. 5 is a plan view showing a main part of the second embodiment.

FIG. 6 is a plan view showing a main part of a third embodiment.

FIG. 7 is a perspective view showing the operation principle of the optical shutter device.

FIG. 8 is a plan view showing a comparative example of the present invention.

[Explanation of Signs] 12 ... Optical shutter chip 12a ... Slant side 41 ... Optical shutter element 42 ... Common electrode 43 ... Individual electrode M ... Electric field direction X ... Main scanning direction Y ... Sub-scanning direction

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yasuyuki Hiromoto 2-13-13 Azuchicho, Chuo-ku, Osaka City, Osaka Prefecture Osaka International Building Minolta Co., Ltd. (72) Yuji Kamoda Inventor, Yuji Amochi, Osaka City, Osaka City 2-3-1, Machicho Osaka International Building Minolta Co., Ltd. F-term (reference) 2H079 AA02 AA13 BA02 CA22 DA04 EB02 EB12 EB15 GA04 HA12

Claims (5)

[Claims] A plurality of optical shutter elements arranged in at least two rows by providing a common electrode and an individual electrode opposed to each other on a substrate made of a material having an electro-optical effect; In an optical shutter device having an optical shutter array linearly juxtaposed parallel to the arrangement direction, each substrate has an inclined side whose side in contact with another adjacent substrate is inclined at a predetermined angle with respect to the arrangement direction of the optical shutter elements. The common electrode is wired substantially parallel to the arrangement direction of the optical shutter elements, the individual electrode is wired substantially parallel to the inclined side of the substrate, and is applied to the optical shutter element from the common electrode and the individual electrodes. Wherein the direction of the electric field is substantially parallel to the inclined side of the substrate. 2. The inclination angle θ of the inclined side of the substrate is 45 ° ≦ θ.
2. The optical shutter device according to claim 1, wherein the angle is <90 [deg.]. 3. The optical shutter device according to claim 1, wherein an interval G between each row of the optical shutter elements is G ≧ 1.5L, where L is an interval between the common electrode and the individual electrode. 4. When the distance between the common electrode and the individual electrode is L, and the dimension in a direction orthogonal to the electric field of one of the common electrode and the individual electrode is W, W / L> 2. The optical shutter device according to claim 1. 5. When the distance between the common electrode and the individual electrode is L, and the dimension in the same direction as the electric field of one of the common electrode and the individual electrode is D, D / L> 0.5. The optical shutter device according to claim 1.