A resonant scanning unit utilizes a "tuning fork" design with a mirror mounted on one arm of the tuning fork and a counterbalance mass mounted on the other arm. A voice coil electromagnetic motor mounted between the arms causes the arms to move in opposite directions. Light generated by a line of LEDs is reflected from the oscillating mirror to generate a raster display. Reaction forces generated by the motions of the mirror and counterbalance mass cancel at the device base, reducing vibration. In addition, the inventive structure allows placement of the mirror pivot point away from the center of the mirror which allows display devices constructed with the structure to be reduced in size. A second embodiment is disclosed in which molded construction reduces assembly cost and time and allows precise tuning of the reaction forces.
RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent application Ser. No. 07/200,645 for LOW VIBRATION RESONANT SCANNING UNIT FOR MINIATURE OPTICAL DISPLAY APPARATUS, filed on May 31, 1988 by Benjamin A. Wells and assigned to the same assignee as the present invention, now U.S. Pat. No. 4,902,083.
A scanning microscope comprises a sample supporting member on which a sample is supported, an optical device which irradiates a light beam to the sample, and a movement mechanism which moves the optical device with respect to the sample supporting member such that the light beam scans the sample. A device photoelectrically detects light radiated out of the portion of the sample, which is exposed to the light beam, an image of the sample being thereby formed. The movement mechanism for moving the optical device or the sample supporting member is constituted of a tuning fork on which the optical device or the sample supporting member is supported, and an excitation device for applying force, the magnitude of which changes periodically, to the tuning fork, and thereby causing the tuning fork to resonate.
A miniature optical scanner includes an electromagnetic drive having stationary magnets and stationary drive coils to minimize the rotational inertia of the scanner and increase the scanner's resonant frequency. The scanner is such that the resonant frequency is manually tunable as well as automatically adjustable to compensate for variables causing frequency drift. The optical scan angle is increased by employing a multiplying mirror with the optical scanner. For a two axis scanning system, the multiplying mirror may be formed of a second optical scanner to increase the optical scan angle relative to both of the axes.
A scanning method and apparatus, the apparatus comprising a fork with first and second forwardly extending tines and a rearwardly extending counterweight member, a mount for supporting the fork at a point between the tines and the counterweight member, and a drive for effecting relative vibration between the tines to provide a fast scan and for driving the fork to provide a slow scan transverse to the fast scan.
A scan assembly and method of manufacture in which the dither mechanism comprises a co-molded dither spring, dither mount and mirror mount. The method comprises positioning a dither spring in a mold fixture, closing a mold over both a free end of the dither spring and a fixed end of the dither spring, placing the mold in an injection molding machine, injecting plastic material into the mold and forming a base mount on the fixed end of the dither spring and a mirror mount on the free end to form the spring assembly, allowing the spring assembly to cool, and removing the spring assembly from the mold.
A scan assembly and method of manufacture in which the dither mechanism comprises a co-molded dither spring, dither mount and mirror mount. The method comprises co-molding a living hinge with a base mount on the fixed end of the living hinge and a mirror mount on the free end of the living hinge. The living hinge may be molded out of the same plastic material as the base mount and mirror mount, or the living hinge may be molded out of a more pliable plastic.
