Piezoelectric illumination control for microscope

Details Piezoelectric illumination control for microscope Piezoelectric illumination control for microscope

1999-06-04

2001-01-30

Wong, Don (Department: 2821)

Electric lamp and discharge devices: systems

Periodic switch in the supply circuit

Silicon controlled rectifier ignition

C315S276000, C315S310000

Reexamination Certificate

active

06181073

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to microscopes, more particularly to a piezoelectric device for controlling illumination in microscopes, and, even more specifically, to an illumination control circuit comprising a lithium niobate crystal.
BACKGROUND OF THE INVENTION
The illumination system is a very important part of a microscope. In fact, the full potential of any optical microscope can only be achieved if the microscope is equipped with the proper kind of illumination system. Specimen illumination also affects operator comfort and efficiency.
It is difficult to determine the best illumination system to achieve optimum illumination, since this depends both on the nature of the specimen to be examined and the type, structure and design of the microscope. For example, the illumination problem is compounded in the case of a stereo microscope, which embodies two separate and complete microscopes. No single illumination system is suitable for examining all types of specimens. Often, different illumination systems are used with the same microscope for different types of specimens. Almost always, there is an optimum illumination system for a particular system.
Various types of illumination systems are known, including, but not limited to the following: Nicholas illuminator, general purpose illuminator, fluorescent illuminator, reflector illuminator, ring illuminator, spot illuminator, coaxial illuminator, eyepiece illuminator, fiber optic annular illuminator, fiber optic bifurcated illuminator, fiber optic four-point illuminator, critical illuminator, and Koehler illuminator. Regardless of the type of illuminator, they all have one thing in common - an illumination element. Some use incandescent lamps, others fluorescent lamps, and some use fiber optics. It is often necessary and/or preferable to vary the intensity of the illumination provided by the light source. Often, this is accomplished by varying the voltage applied to the illumination element by way of an electrical rheostat. Unfortunately, rheostats are relatively expensive and can be bulky.
There is a need, then, for a device for controlling illumination in microscopes and in other devices which does not require an expensive, bulky electrical rheostat.
SUMMARY OF THE INVENTION
The invention broadly comprises a piezoelectric illumination control circuit for a microscope, comprising a tunable frequency source of alternating current, a piezoelectric crystal having an impedance dependent on operating frequency, driven by the tunable frequency source of alternating current, and, a load driven by the piezoelectric crystal. A second embodiment comprises a piezoelectric illumination control circuit for a microscope, comprising a constant frequency source of alternating current, a piezoelectric crystal coupled to a tunable dummy reactive load for the purpose of varying the impedance of the crystal and dummy load, the piezoelectric crystal driven by the constant frequency source of alternating current, and, a load driven by the piezoelectric crystal. Although a preferred embodiment of the invention is intended for use in controlling intensity of lamps in microscopes, the circuit of the invention can be used to control loads in other circuits as well.
A primary object of the invention is to provide an economical and efficient circuit for controlling the intensity of a lamp in a microscope.
A secondary object of the invention is to provide a replacement for a rheostat in a microscope.
Another object of the invention is to provide a replacement for both a step-down transformer and a rheostat in an illumination control circuit for a microscope.
A further object of the invention is to provide a replacement for a ballast in a microscope containing a fluorescent lamp.
These and other objects, features and advantages of the present invention will become readily apparent to those having ordinary skill in the art from the follow detailed description of the invention in view of the drawings and appended claims.


REFERENCES:
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patent: 3764848 (1973-10-01), Berlincourt
patent: 3980921 (1976-09-01), Izawa
patent: 4025817 (1977-05-01), Wollschleger
patent: 5134345 (1992-07-01), El-Hamamsy et al.
patent: 5229680 (1993-07-01), Sato et al.
patent: 5675208 (1997-10-01), Huang et al.
patent: 5739679 (1998-04-01), Takehara et al.
patent: 5856728 (1999-01-01), Zimnicki et al.

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