DD297240A5 - METHOD FOR MEASURING THE PUNCTUAL INCREASE OF REMISSIONS, REFLECTIONS AND TRANSMISSION SPECTROS BY MEANS OF ONLY ONE LED - Google Patents

Abstract

The invention relates to a method for mesztechnische detection of the punctual increase of reflectance, reflection and transmission spectra. The method can be used both in colorimetry for determining the spectra sought and in other processes in which the control and / or monitoring of the spectral constancy / change of materials is significant. According to the invention, the point increase in reflectance, reflection and transmission spectra is detected by varying the wavelength emitted by an LED (10) by pulse width modulation of the current If (t) flowing through the LED (10), the remitted, reflected or transmitted Light pulses of the LED (10) of the receiver (11) converted into an electrical Groesze and only at the end of each pulse of the LED (10) for further processing (MWUES) and stored until the next query (MWUEH). Fig. 1 {remission spectrum; Reflection spectrum; Transmission spectrum; point increase; Pulse width modulation; Farbmesztechnik; spectral changes; spectral constancy; LED}

Description

For this 2 pages drawings

Field of application of the invention

The invention relates to all application cases in which measuring technology is detected by means of LED reflectance, reflection and separation spectra.

Characteristic of the known state of the art It is a device for the punctual determination of 3 remission grades by means of 1 red, 1 green and 2 blue LEDs (GB: Q01N 21/27 2165842) and a patent (DD: Q01J 3/50 99439) for optoelectronic point detection of several Remission grades and subsequent calculation of parts of the remission spectrum known, wherein for the measurement

and calculating a degree of remission, an LED is needed and for the faithful representation of the entire spectrum, a very large number of LEDs is needed.

Further patents for the determination of spectra by means of optoelectronic components, without filters or mechanically moved Parts are not known. These devices are only for the selective detection of reflectance, reflection and transmission spectra by means of LEDs

and radiation receivers.

There are a lot of LEDs of different wavelengths and thus a long measurement time needed to a spectrum

characterize.

Especially with large fluctuations in the functional characteristics of the spectra there are problems of metrological detection

by means of opto-electronic components.

Object of the invention The aim is the cheap, fast and accurate detection of reflectance, reflection and transmission spectra. Explanation of the essence of the invention The invention is based on the object, the punctual increase of reflectance, reflection and transmission spectra in Range of the center wavelength of an LED to capture. According to the invention the object is achieved in that each one of the metrological determination of the spectra

required LED (10) is traversed with a pulse width modulated current I = f (t) in the ampere range in such a way that the known and previously undesirable crystal warming, which is the cause of a preferred expiration of

Recombination processes under photon uptake and thus for a longer wavelength emitted radiation is exploited,

to irradiate by means of an LED (10) the sample to be measured with η different wavelengths and thereby provide η measured values of the optoelectronic receiver (11) for further computational evaluation.

The pulse duration of the current I = f (t) driving the LED is to be chosen such that the current through the current I = f (t)

caused crystal warming does not lead to irre-sensitive structural changes in the crystal structure of the LED (10).

AusfOhrungsbetsplol The invention will be explained in more detail with reference to the accompanying drawings. Ee show Flg. 1: Course of Tents: I - f (t) Tasks of Measured Value Transfer (MWÜ)

Flg. 2: Circuit realization of the control of the LEO (10) and synchronous preprocessing of the measured values received by the optoelectronic receiver (11):

The clock generator (1) generates a pulse train, which is modulated by the pulse shaper (2) In their pulse width and Otter the LED driver (3) de: LED (10) is supplied.

The delay element (4) ensures a pulse width-dependent shortening of the LED pulses, so that the output signal of the optoelectronic receiver (11), which is preprocessed by the amplifier (6), only at the end of each transmission pulse of the LED (10) by the sample & hold Circuit (7) (MWÜ ·> S) and provided for the ADU (8) until the next measured value is taken over (MWÜ = H). Via an interface to the computer (9), the values converted in the ADU are transferred to the computer for further computational evaluation. This controls via the interface to the computer (9) the logic decoder (6), the pulse shaper (2) and the delay element (4), d. H. It is a software setting of Tastverhältnieses and the pulse width of the LED (10) driving signal possible.

Claims (3)

1. A method for metrological detection of the punctual increase of reflectance, reflection and Transmlsslonsspekti s by means of only one LED, characterized in that an LED (10) by a pulse width modulated current I · = · f (t) is traversed so that their emitted Wavelength corresponding to I = f (t) changed, wherein the emitted radiation of alternating wavelength irradiates the sample to be examined and the remitted from the sample, reflected or transmitted radiation from an optoelectronic receiver (11) is measured and provided for further calculation , wherein the measuring time of the optoelectronic receiver (11) is smaller than the smallest emission time of the LED (10), wherein LED (10) and optoelectronic receiver (11) are driven synchronously. 2. The method according to claim 1, characterized in that the pulse width modulated current I = f (t) is 0.5 ... 10A and the pulse duration is in the ηβ.,. Μβ range. 3. The method according to claim 1, characterized in that preferably optoelectronic receiver (11) are used due to the kurzon measuring time in the us range.