This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-390217, filed Dec. 21, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an optical deflector and optical deflector array which use a micro machine technique to deflect light.
2. Description of the Related Art
In recent years, an optical deflector has been noted which uses a MEMS technique. This technique is disclosed, for example, in U.S. Pat. No. 4,317,611. As shown in FIG. 1A, the optical deflector includes a rotor portion 4 formed of silicon and torsion bars 6, 8 disposed on a rotation shaft of the rotor portion 4. Moreover, the rotor portion 4 is connected to a semiconductor plate portion 2 via the torsion bars 6, 8. These rotor portion 4, torsion bars 6, 8, and semiconductor plate portion 2 are formed integrally from the same silicon substrate. The semiconductor plate portion 2 functions as a support member which supports the rotor portion 4.
On the other hand, a substrate (hereinafter referred to as an electrode substrate) 10 on which an electrode for driving is formed under the substrate which forms the rotor portion 4. In the electrode substrate 10, an annular concave portion 12 is formed around the rotor portion 4 and torsion bars 6, 8. Moreover, in the annular concave portion 12, a continuously formed island-shaped portion 14 is positioned on the rotation shaft of the rotor portion 4.
Furthermore, two conductive elements for driving (hereinafter referred to as driving electrodes) 16, 18 are formed symmetrically with the island-shaped portion 14 as an axis. The driving electrodes 16, 18 are formed to extend to ends of the electrode substrate 10 beyond the annular concave portion 12. The electrode substrate 10 is bonded to the semiconductor plate portion 2 to constitute an optical deflection apparatus.
The optical deflection apparatus constituted as described above is driven by an electrostatic attraction force by voltages applied to two driving electrodes 16, 18. Therefore, a deflection angle of the rotor portion 4 is determined by a difference of voltages applied to both the electrodes 16, 18. Moreover, the rotor portion 4 contacts the island-shaped portion 14 by the electrostatic attraction force, and is deflected using a contact surface with the island-shaped portion 14 as a base point of rotation.
Moreover, in the above-described publication, application using the optical deflection apparatus is also disclosed. As shown in FIG. 1B, the optical deflection apparatus is constituted of an optical deflector and an electrode substrate 10xe2x80x2. The optical deflector includes a semiconductor plate portion 22 in which two rotor portions 24, 24xe2x80x2 on the same substrate are formed in parallel in a direction crossing at right angles to the rotation shaft. Moreover, the electrode substrate 10xe2x80x2 includes a fixed mirror 30 for deflecting a light 28 from a light source 26 reflected by the first rotor portion 24 to the second rotor portion 24xe2x80x2.
That is, in this constitution, two rotor portions 24, 24xe2x80x2 formed in parallel can be used to increase a deflection angle as shown by an arrow 32.
Moreover, in the above-described publication, there are also described two rotor portions arranged so that the rotation shafts cross at right angles to each other. This has an advantage that the light can two-dimensionally be deflected via the fixed mirror.
However, in the above-described optical deflector, since a torsion bar portion for connection to the semiconductor plate portion is disposed on the rotation shaft, rotors cannot be arranged in a rotation shaft direction without any gap. Therefore, the above-described optical deflector is not suitable for a constitution in which the rotors are densely arranged in the rotation shaft direction.
For example, for use as a micro optical deflection element in a scanning type optical apparatus described in Jpn. Pat. Appln. KOKAI Publication No. 2001-116696, it is necessary to arrange the rotor portions in a direction parallel to the rotation shaft without any gap. This is because the micro optical deflection element has a purpose of introducing the divided lights into a plurality of optical detection apparatuses with an arbitrary wavelength width. When an interval from the adjacent rotor portion is broad, spectral characteristics are adversely affected. Moreover, the rotor portions cannot be arranged in the rotation shaft direction without any gap in the above-described conventional optical deflector. Therefore, there is a problem that the spectral characteristics are deteriorated.
Therefore, an object of the present invention is to provide optical deflectors which can densely be arranged in a rotation shaft direction.
Another object of the present invention is to provide an optical deflector array using optical deflectors which can densely be arranged in the rotation shaft direction.
To achieve the objects, according to one aspect of the present invention, there is provided an optical deflector comprising:
a movable plate having a reflection surface and an opposite surface opposite to the reflection surface;
a support member including a confronting substrate which confronts the opposite surface of the movable plate;
at least one elastic member having two ends, one end being supported by the support member and the other end being attached to the movable plate, and extending in a first direction extending from the one end to the other end; and
driving member for driving the movable plate to rock with respect to the support member with using a second direction normal to the first direction as a rock axis,
the confronting substrate having a contact area which defines a maximum deflection angle of the movable plate and restricts the rocking movement of the movable plate within the maximum deflection angle, and
the contact area having a first and a second deflection position with which the movable plate is brought into contact when the driving member applies a driving force to the movable plate.
According to another aspect of the present invention, there is provided an optical deflector array wherein a plurality of the above-mentioned optical deflectors are arranged in the second direction parallel to the rock axis.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.