JPS6235321A - Electric machine light modulating element - Google Patents

Abstract

PURPOSE:To enlarge the swinging angle of a mirror swinging part and to increase a dielectric breakdown voltage by providing the insulating low viscosity liquid between the substrate and the mirror swinging part. CONSTITUTION:An insulating low viscosity liquid 19 is injected into the air gap. Generally, a specific inductive capacity of the liquid 19 is 2 or above and high, the dielectric breakdown voltage can be increased by using the liquid with the high insulation and a distance (d) betweem gaps can be made small. Namely, a bending force F of the mirror is in proportion to an area S of the mirror and in inverse proportion to the distance (d) between the gaps and therefore, a larger bending force F functions compared with the bending force at the time of the air gap. In other words, even when the voltage to impress for a DMD, etc., is the same as the conventional voltage, large swinging angle can be obtained, and the impressed voltage to obtain the same swinging angle can be lowered.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an electromechanical light modulation device, and particularly relates to an electromechanical light modulation device in which a minute mirror swings. [Prior Art] An electromechanical light modulation device as described above For example, DM
D (Deformabla Mirror Devi
ce) is known.

Regarding DED, IEEE Transaction
onElectron Device Vol, ED
-30A5544 (1983), and the optical system is also disclosed in JP-A-59-17525.

The general mechanism of the DMD will be explained below based on the drawings.

FIG. 2 (&) shows an enlarged sectional view of the DMD. Reference numeral 1 indicates a mirror structure, which is made of a material such as At or Ag, and serves to reflect incident light. Reference numeral 2 denotes a substrate that supports the mirror structure of 1 and is made of Au or the like. 3 and 4 are supporting members of 1 and 2,
Reference numeral 3 is called a mirror contact, and in particular it receives a tip part that performs electromechanical operation, and 4 is made of polyoxide S.
It is an insulating material of t.

5 is a polysilicon gate which plays the role of an MO8 type FET transistor node. 6 is the air gap, 0.
It is a cavity of 6μ to several μ. 7 is a floating field plate, and a voltage is applied from the N+ floating source of 8 to the floating field plate of 7 based on the ON/OFF information of the transistor. 9 is N
+ indicates drain. This also serves as the structure of the MO8 type FET transistor.

10 is dirt oxide, and 11 is a P-type silicon substrate.

FIG. 2(b) is an enlarged front view of FIG. 2(a) from the entrance direction, where 12 is an air gap, 13 is an electromechanically oscillating mirror swinging portion, and 14 is a base portion.

Reference numeral 15 indicates the mirror surface other than the mirror swinging portion 13 on the surface of D~. A DMD is manufactured in a process similar to that of an IC or LSI. Figure 2 (c) shows a mistaken equivalent diagram of a DVD. 16 is 1
．． 2 shows the 'd pressure vM applied to the mirror and support member of No. 2.

17 indicates the voltage V applied to 8. 18 shows the transistor configuration, D (drain) signal of 9, 0 of 5
(f-g) Signal ON, OFF The voltage of FC side V2 is turned ON and OFF at 8. At this time, a voltage is applied to 1°2, and a potential difference is ON between 1, 2 and 8.
, the OFF signal will be increased or decreased.

At this time, a force F according to the following formula is generated between 6 and 7 depending on the potential difference, and F'c/3KVQ (K: constant v: position difference α: constant F
: bending force) The mirror 1.2 is swung by the arch 14. Figure 2 (a
) shows the case where there is a large voltage difference between 1, 2 and 8, the mirror swinging part 13 bends from the hinge part 14, and due to this action the incident light bends at an angle twice the deflection angle of the mirror. Instead, it is reflected.

On the other hand, when the voltage difference is small, as shown in the right diagram of Fig. 2(a), the force exerted by the mirror swinging portion 13#''l of 1.2 is small and the incident light is not bent. It will be reflected when the mirror does not touch.DMD means electrical ON/OFF is controlled by the oscillation of the mirror oscillating unit 13.
It converts into N and OFF, and further into the deflection angle of light.

[Problem that the invention seeks to solve]

However, in the above-mentioned MD, the angle of light deflection is about 4 degrees at maximum due to the settings of the air gap, applied voltage (approximately 3 Q volts), etc. An optical system using a DMD is necessarily a reflective optical system, which alone requires high precision, but if we also have to build an optical system that can withstand angle changes of only 4 degrees, the optical system There was a problem in that the accuracy needed to be extremely high, and position adjustment was also extremely difficult.

[Means for solving problems]

In view of the problems of the prior art as described above, in the present invention, in order to increase the deflection angle of the mirror swinging section 13, the substrate and the mirror swinging section disposed close to the substrate are provided with static electricity. In an electromechanical light modulation element such as a DMD that can deflect reflected light in at least two directions by being oscillated by force, a method is taken to provide an insulating low-viscosity liquid between the substrate and the mirror oscillating portion.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an enlarged cross-sectional view of the electromechanical light modulator of the present invention. In this figure, the same members as in FIG. 2 are given the same numbers. In the present invention, an insulating low viscosity liquid 19 is injected into the air gap f6 shown in FIG.

In general, the liquid 19 has a high dielectric constant ε of 2 or more, and by using a highly insulating liquid, the dielectric breakdown voltage can be increased and the gap distance d can be reduced.

That is, the bending force F of the mirror is proportional to the area S of the mirror and inversely proportional to the distance dK between the gears, so if the relative dielectric constant of the liquid 19 is e, in this case Focc&or (ε. is the dielectric constant of vacuum), A larger bending force F acts than when there is an air gap. Even if the voltage applied to the pick, DMD, etc. is the same as in the past, a larger deflection angle can be obtained, or the applied voltage can be lowered to obtain the same deflection angle.

Examples of the insulating low-viscosity liquid 19 include silicone oil, sulfonic oil, fluorine oil, chlorine-substituted aromatic hydrocarbon, and the like.

Furthermore, when manufacturing the electromechanical light modulation element of the present invention,
It is desirable that the surface of the swinging mirror 13 be made of a material with low surface free energy so that the injected liquid 19 can be retained within the element by capillarity. Furthermore, the viscosity of the injected liquid 19 is preferably low in terms of response;
The lower the vapor pressure of 9, the better.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to increase the deflection angle of the mirror swinging part by a simple method, and it is also possible to increase the dielectric breakdown voltage by using a highly insulating liquid. Became.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of the electromechanical light modulation element of the present invention. FIG. 2 is an explanatory diagram of a conventional electromechanical light modulation element. 11: P-type silicon substrate, 13: Mirror swinging section, 19:
jQ marginal low viscosity liquid. Agent Patent Attorney Sekihei Yamashita Figure 1

Claims (1)

[Claims] (1) An electrical device that has a substrate and a mirror swinging section disposed close to the substrate, and can deflect reflected light in at least two directions by electrically swinging the mirror swinging section. An electromechanical light modulation element, characterized in that an insulating low viscosity liquid is provided between a substrate and a mirror swinging part.