The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 30, 1989
Filed:
Mar. 06, 1987
Ricoh Company, Ltd., Tokyo, JP;
Abstract
An apparatus for measuring the refractive index of liquid particularly suitable for use in an ink-jet printing system is provided. The apparatus includes a light emitting diode and a photodiode which are optically coupled by an optical fiber which in turn is partly immersed in a liquid to be measured. In one aspect, the wavelength of light emitted from the light emitting diode is so set to be outside a light absorption wavelength range of the liquid to be measured. In another aspect, provision is made of a temperature dependent resistor which changes its electrical resistance depending on the temperature of the liquid to be measured so as to vary the level of the driving current to be applied to the light emitting diode thereby varying the amount of light to be emitted.