Optical: systems and elements – Deflection using a moving element – By moving a reflective element
Reexamination Certificate
1999-11-10
2001-03-06
Phan, James (Department: 2872)
Optical: systems and elements
Deflection using a moving element
By moving a reflective element
C359S214100
Reexamination Certificate
active
06198565
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light deflection element that reflects and deflects light of a laser beam or the like, and to a display uses such a light deflection element.
2. Description of the Related Art
Light deflection elements are used in scanners of optical equipment such as electronic photocopiers, laser beam printers and barcode readers, in optical deflection apparatus such as optical disk (disc) tracking controllers, and in display apparatus in which a laser beam is scanned and an image is projected.
Typical elements used as light deflection elements include a rotating polygonal mirror and a galvano mirror, the galvano mirror featuring the ability to make a more compact mechanism than in the case of a rotating polygonal mirror, and using recent semiconductor microprocess technologies there have been reports of micromirrors using silicon substrates, leading to the expectation of even further improvements in compactness, light weight, and low cost.
An example of the above-noted galvano mirror type of light deflection element is disclosed in the Japanese patent application laid-open publication H8-211320. In this related art example, when a voltage is applied between one fixed electrode and a reflective mirror, the left side of the reflective mirror is attracted because of an electrostatic force, so that the reflective mirror rotates in the counterclockwise direction about a pair of beams as an axis, and when a voltage is applied between another fixed electrode and the reflective mirror, the right side of the reflective mirror is attracted by an electrostatic force, so that the reflective mirror rotates in the clockwise direction about the pair of beams as an axis. Therefore, by applying alternately applying a voltage to a pair of fixed electrodes using a driving apparatus, it is possible to cause the reflective mirror to swing to the left and right. Light that is shone onto this reflective mirror is reflected at an angle that changes in accordance with the swing of the reflective mirror, the light being thereby deflected.
In the example of the past, however, to achieve a large swing (deflection) angle with a reflective mirror, it is necessary to establish a large gap between the reflective mirror and the fixed electrodes. However, because the electrostatic force is inversely proportional to the square of this gap, to achieve the required drive force, an extremely large voltage is required, thereby making this approach substantially impractical.
Another example of related art is disclosed in the Japanese patent application laid-open publication H8-334723. In this related art example, a drive apparatus has a pair of left and right permanent magnets disposed on a base and a drive coil disposed around the periphery of a reflective mirror, a drive current alternating between positive and negative being passed through this drive coil. In this configuration, when a drive current alternating between positive and negative is passed through the drive coil, a Lorentzian force generated because of the outer magnetic field of the pair of permanent magnets and the current through the drive coil act to cause the reflective mirror to swing about a pair of beams as an axis.
In the above-noted related art example, however, while because there is no limitation to the deflection angle such as in the case of the previously described electrostatic drive, it is possible to achieve a large deflection angle, because of the drive coil disposed around the periphery of the reflective mirror, the size of the reflective mirror increases, making this approach unsuitable for high-speed deflection.
Additionally, in both the cited related art examples, because drive force is directly applied to the reflective mirror, it is necessary to configure the drive apparatus so that it does not interfere with the swinging of the reflective mirror, this representing a limitation to the degree of freedom in configuring the drive apparatus.
SUMMARY OF THE INVENTION
The present invention was made to solve the problems of the above-noted drawbacks. and has as an object to provide a light deflection element that provides a high degree of freedom in configuring a drive apparatus, this light deflection element being suitable for high-speed deflection at a high deflection angle, and to provide a display apparatus using the above-noted light deflection element.
From the first aspect of the present invention, there is provided a light deflection element that has a first oscillating element having two arms, the outer ends of which are fixed to one of a pair of supports provided at a distance from one another, and the inner ends of which are free ends, a second oscillating element having two arms, the outer ends of which are fixed to the other of the pair of supports, and an inner ends of which are free ends, a reflective mirror disposed between the two arms of each of the pair of oscillating elements, first torsion springs linking the inner ends of each of the arms of the first oscillating element to positions of the reflective mirror in proximity to and at a first position that is symmetrical about an axis that passes through the center of gravity of the reflective mirror, second torsion springs linking the inner ends of each of the arms of the second oscillating element to positions of the reflective mirror in proximity to and at a second position that is symmetrical about an axis that passes through the center of gravity of the reflective mirror, and a drive apparatus that applies a drive force to at least one of the pair of oscillating elements separately and independently, thereby causing the inner ends of the arms to move up and down separately and independently.
According to the above configuration, because drive force from each arm of the pair of oscillating elements acts in the region of the swinging (rotational) center of the reflective mirror, via the torsion springs, it is possible to achieve a large swing angle with a small drive stroke, thereby making it unnecessary to dispose a member of the drive apparatus at the reflective mirror, which enables the use of a small reflective mirror, thereby further enabling high-speed deflection to a large deflection angle. Additionally, because the drive apparatus is configured so as to act independently on the pair of oscillating elements, in contrast to the case in which the reflective mirror is directly driven, it is possible to achieve a high degree of freedom in configuring the drive apparatus, without the need to consider the swing of the mirror.
From the second aspect of the present invention, there is provided a light deflection element that has a first oscillating element having two arms, the outer ends of which are fixed to one of a pair of supports provided at a distance from one another, and the inner ends of which are free ends, a second oscillating element having two arms, an outer ends of which are fixed to the other of the pair of supports, and the inner ends of which are free ends, a reflective mirror disposed between the two arms of each of the pair of oscillating elements, first torsion springs linking the inner ends of each of the arms of the first oscillating, element to positions of the reflective mirror in proximity to and at a first position that is symmetrical about an axis that passes through the center of gravity of the reflective mirror, second torsion springs linking the inner ends of each of the arms of the second oscillating element to positions of the reflective mirror in proximity to and at a second position that is symmetrical about the axis that passes through the center of gravity of the reflective mirror, and a drive apparatus that applies a drive force to the four arms of the pair of oscillating elements separately and independently, thereby causing the inner ends of the arms to move up and down separately and independently.
According to the above-noted configuration, because the drive force from each arm of the pair of oscillating elements acts in the region of the swinging (ro
Iseki Takayuki
Oguri Katsuhiko
Yagyu Shingo
Cherry Euncha
Nath Gary M.
Nath & Associates PLLC
Novick Harold L.
Phan James
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