WO2011138483A1 - Device for measuring colour in liquids - Google Patents

Device for measuring colour in liquids Download PDF

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Publication number
WO2011138483A1
WO2011138483A1 PCT/ES2011/070235 ES2011070235W WO2011138483A1 WO 2011138483 A1 WO2011138483 A1 WO 2011138483A1 ES 2011070235 W ES2011070235 W ES 2011070235W WO 2011138483 A1 WO2011138483 A1 WO 2011138483A1
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Prior art keywords
cavity
liquid
reflection surface
color
light
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PCT/ES2011/070235
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Spanish (es)
French (fr)
Inventor
Agustín GAGO SALVADÓ
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Gago Salvado Agustin
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Publication of WO2011138483A1 publication Critical patent/WO2011138483A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour

Definitions

  • the invention relates to a device for the measurement of color in liquids, which has characteristics aimed at obtaining adequate precision and stability in applications where so far the color comparison is carried out visually.
  • This device is applicable in those fields in which a chromatic analysis of a liquid is necessary. Background of the invention.
  • Another known and widely used technique is based on measurement by colorimetric reaction. This technique is used both in applications that require great precision, as in those in which only a qualitative identification of the parameter to be measured needs to be made.
  • the principle of operation of this technique is based on the chemical interaction between a specific chemical reagent and the desired physicochemical parameter. to size. This chemical reaction generates a final color that is proportional to the concentration of the parameter being measured.
  • the visual methods are carried out in two steps: first a specific volume of the sample to be analyzed is taken, to which a reagent that develops a color proportional to the concentration of the element to be analyzed is added.
  • the color generated in the sample is compared with a printed color chart that collects some reference points. In this way, the user, by comparison with the references, identifies the concentration of the element under analysis.
  • the main advantage of this technique is its low cost. Its great drawback is the low precision, determined by two factors: the subjectivity of the color reading by the user, and the low resolution, since a few reference colors are normally printed on the reference table. It should be taken into account that between 50 and 80% of the total measurement error is determined by the subjective reading of the color by the user.
  • Photometric methods like visual ones, are carried out in two steps. The first one is exactly the same as the previous method. The difference comes in the final step, in which the color measurement is made using electronic equipment that is able to analyze the color by optical and electronic methods.
  • This method offers great precision, since the subjective quantification of the color increased in turn increases the resolution of the measure since it is not based on the comparison of a few reference colors;
  • this photometric method requires the use of devices that incorporate optical elements, such as diffraction prisms, collimators or optical filters for specific wavelengths, which considerably increases the cost of the equipment.
  • the technical problem raised is the development of a device that, being of relatively low cost, substantially improves the results obtained with respect to visual methods.
  • the device of the invention has characteristics, aimed at quantifying the parameter to be measured, by measuring the color of a liquid sample, in which, as in the techniques described, a specific reagent will have been previously added.
  • this device comprises:
  • a housing that extends into a sealed and transparent probe intended to be introduced into the liquid to be analyzed and which has at least a first cavity intended to be introduced into the liquid to be analyzed
  • a color sensor housed in the first cavity, which collects the light projected by the light emitter through the liquid contained in the intermediate chamber and reflected on the reflection surface and converts it into a processable electrical signal
  • control unit for processing the signals provided by the color sensor and data storage
  • the color measurement of the liquid is carried out by immersion of a probe into the liquid to be measured, so that the liquid accesses an intermediate chamber, which allows the use of the device without using external cuvettes, used in other standard photometric methods;
  • the color measurement of the liquid is made by reflection of the light emitted against a surface that functions as a reflection background;
  • the color measurement is performed in a relative way, characterizing the sensor reading against different known patterns and checking the color reading; the resulting color measure It is done by interpreting one or more color channels. In this way, RGB measures can be made complementary to the main channel, which allows obtaining additional information from the sample.
  • this device has a great simplicity of use, since it is enough to submerge the probe in the liquid, so that it completely occupies an intermediate cavity located between the sensor and the reflection surface and turn on the emitter of light for long enough for the optical measurement cavity to illuminate.
  • the color sensor detects the light reflected on a reflection surface. Having passed this light through the liquid to be measured, the spectral content of the reflected light is the same as that of the liquid under measure.
  • the reflection surface may be in contact with the liquid, outside the first cavity, or be housed in a second cavity of the probe.
  • the intermediate chamber for liquid access is disposed between the first and second cavity of the probe.
  • the measurement is carried out in the liquid housed in an intermediate chamber located inside the device, which is not attainable by the user or by other external elements that could modify its operation. Therefore the characterized behavior is not altered with time or manipulation. Since the intermediate chamber is integrated in the equipment itself, it must never be replaced, thus reducing the maintenance costs of the equipment.
  • This device reduces the cost of the equipment, since all the electronics are on the same printed circuit board.
  • the intermediate chamber in which the liquid to be analyzed is introduced can be of very small dimensions, allowing analysis in smaller liquid samples (lower sample and reagent costs). This also allows analysis to be performed within narrow sample tubes that can be made of conventional transparent or opaque conventional plastic more economically.
  • a color measurement is made using three color channels. R, G and B. allowing more complete color analysis than conventional photometers, which only analyze one wavelength at the same time; getting complementary information on the reagent status, colors out of range and other variables,
  • the equipment can be used to make indirect measurements of chemical parameters in liquids. As explained above through chemical reagents, either for absolute measurement of colors in liquids for other purposes such as quality control, production control, process regulation, etc.
  • a temperature sensor can be included near the color sensor and the sensor signal can be compensated via hardware or software.
  • the design of the optical camera can be modified to totally prevent external light from entering it.
  • mechanical filters can also be used in the liquid inlet of the chamber.
  • FIG. 1 shows a perspective view of an embodiment of the invention.
  • FIG. 2 shows a schematic profile view of the device of the previous figure, sectioned by a vertical plane.
  • FIG. 3 shows an enlarged detail of the end of the probe, sectioned by a vertical plane, to allow observation of the intermediate chamber and the elements housed in the two interior cavities.
  • FIG. 4 shows a general block diagram, with the different functional elements of the device of the invention.
  • FIG. 5 shows a block diagram of the control unit.
  • FIG. 6 shows a block diagram of the light emitter.
  • FIG. 7 shows a block diagram of the device power unit.
  • the device of the invention comprises a housing (1) that extends into a sealed and transparent probe intended to be introduced into the liquid to be analyzed and which has a first cavity (2) and a second cavity (3) among which an open intermediate chamber (4) is defined, for the access of the liquid to be analyzed.
  • a light emitter (5) for the projection of light is housed, through the liquid contained in the intermediate chamber (4) towards a reflection surface (6) housed in the second cavity (3 ), and a color sensor (7) that collects the light projected by the light emitter (5) through the liquid contained in the intermediate chamber (4) and reflected in the reflection surface (6), converting it into a signal Processable electrical
  • the probe of the device has a diameter of less than 25 millimeters, which allows the measurement of color within conventional cuvettes, widely used in this field.
  • the light emitter (5) is made up of an LED diode (51) connected through a constant current source (52) with a voltage regulator (53).
  • the reflection surface (6) housed in the second cavity (3) of the probe is formed of a non-light absorbing material and preferably white in order to allow the light to reflect without distortion of any color.
  • the color sensor (7) connected to a control unit (8) responsible for processing the signals provided by the color sensor (7) and data storage. It comprises an RGB sensor, LDR or equivalent element of commercial electronics,
  • the device additionally comprises an electric power supply unit (9), user inputs (10) for operating the device, a display screen (1 1) of the parameters obtained and communication ports (12) for eventual connection of the device with an external computer.
  • the control unit (8) comprises a processor (81), a memory (82) with the calibration data for the storage of data relating to the behavior of the measuring device before different optical stimuli for estimating the concentration of any parameter a through reference points, and a program memory (83).
  • This control unit (8) characterizes the reading of the color sensor (7) against different known patterns and checks the reading of colors, making the visualization of the parameters obtained in the display screen (12).
  • the power unit (9) comprises batteries, rechargeable batteries or connection to the mains (91), a protection (92) against reverse connection and a regulator (93).
  • the display screen (12) is constituted by an LCD display.
  • the probe has an indicator (13) of the minimum level of immersion in the liquid to be analyzed, in order to avoid insufficient immersion in the liquid and obtaining measurement errors.
  • the measurement of the color of the liquid must be done in a time sufficient for the color sensor (7) to be able to detect the received light.
  • the minimum time depends on the color sensor technology (7). For semiconductor sensors, it is usually 1 to 10 milliseconds, for LDR sensors it can be higher.
  • a calibration of the device For the determination of the concentration of parameters in a sample, a calibration of the device must be carried out previously, exposing the measuring probe to different concentrations of the element to be measured at which it has been Measurement reagent added. The results are stored in a memory (82) for later comparison with other measures.
  • the calibration or characterization of the behavior makes it possible to compensate for possible reflection or refraction effects within the intermediate measuring chamber (4).
  • the resolution of the measurement can be much greater since having the characterized behavior can interpolate intermediate points.
  • the user inputs (10) are represented by an on / off key, a selection key and a test key.
  • Any of these keys can also be used to perform calibration or equipment adjustment functions. For example, zero adjustment of the equipment before making a measurement.
  • the selection key allows you to choose the parameter to analyze. Once selected, pressing the test key analyzes the color of the liquid, the color is analyzed and the measurement result is displayed on the display screen (1 1) or the LCD display.
  • the reflection surface (6) is white; however, it could be a surface of any other color if a measurement is desired in a narrower spectrum.
  • the communication ports (12) allow the connection of the device with a computer to update the equipment program, load additional programs, or download the measures obtained.

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  • Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)

Abstract

The invention relates to a device for measuring colour in liquids, comprising: a casing which extends into a probe to be inserted into the liquid to be analysed, said casing including a first cavity to be inserted into the liquid to be analysed; a reflection surface disposed outside the first cavity, with a liquid inlet chamber being provided between the reflection surface and the first cavity; a light emitter for projecting light through the liquid located in the intermediate chamber towards the reflection surface; a colour sensor which collects the light projected by the light emitter through the liquid in the intermediate chamber and reflected on the reflection surface and which converts same into a processable signal; a control unit for processing signals originating from the colour sensor and storing data; and user inputs for managing the device.

Description

DESCRIPCIÓN  DESCRIPTION
DISPOSITIVO PARA LA MEDICIÓN DE COLOR EN LÍQUIDOS Objeto de la invención DEVICE FOR COLOR MEASUREMENT IN LIQUIDS Object of the invention
La invención se refiere a un dispositivo para la medición de color en líquidos, que presenta unas características orientadas a obtener una precisión y estabilidad adecuadas en aplicaciones en las que hasta ahora se realiza la comparación de color visualmente.  The invention relates to a device for the measurement of color in liquids, which has characteristics aimed at obtaining adequate precision and stability in applications where so far the color comparison is carried out visually.
Campo de aplicación. Scope.
Este dispositivo es aplicable en aquellos campos en los que es preciso realizar un análisis cromático de un líquido. Antecedentes de la invención.  This device is applicable in those fields in which a chromatic analysis of a liquid is necessary. Background of the invention.
Actualmente son conocidas diferentes técnicas para realizar la medida o estimación de elementos físico-químicos en líquidos.  Currently, different techniques are known for measuring or estimating physicochemical elements in liquids.
Una de estas técnicas se basa en la utilización de sondas electrónicas con electrodos sensitivos. Esta técnica suele presentar muy buena precisión y permite medidas continuas del parámetro, por ese motivo se suelen usar en aplicaciones de control. Su principal inconveniente es el número limitado de parámetros disponibles. Los más comunes son las sondas de pH, REDOX o conductividad. Este tipo de sondas funcionan como transductores de parámetros químicos. Convierten el parámetro químico que se desea medir en una variable eléctrica que permite su posterior procesado.  One of these techniques is based on the use of electronic probes with sensitive electrodes. This technique usually has very good precision and allows continuous parameter measurements, which is why they are often used in control applications. Its main drawback is the limited number of available parameters. The most common are pH, REDOX or conductivity probes. These types of probes function as chemical parameter transducers. They convert the chemical parameter that you want to measure into an electric variable that allows its subsequent processing.
Otra técnica conocida y ampliamente utilizada se basa en la medición por reacción colorimétrica. Esta técnica se usa tanto en aplicaciones que requieren una gran precisión, como en aquellas en las que solo se necesita hacer una identificación cualitativa del parámetro a medir.  Another known and widely used technique is based on measurement by colorimetric reaction. This technique is used both in applications that require great precision, as in those in which only a qualitative identification of the parameter to be measured needs to be made.
Su principal ventaja es que se puede medir un rango de parámetros muy amplio a un coste moderado. Su mayor inconveniente es que requieren de un elemento que realice la identificación del color.  Its main advantage is that a very wide range of parameters can be measured at a moderate cost. Its main drawback is that they require an element that identifies the color.
El principio de funcionamiento de ésta técnica se basa en la interacción química entre un reactivo químico específico y el parámetro fisicoquímico que se desea medir. Esta reacción química genera un color final que es proporcional a la concentración del parámetro que se está midiendo. The principle of operation of this technique is based on the chemical interaction between a specific chemical reagent and the desired physicochemical parameter. to size. This chemical reaction generates a final color that is proportional to the concentration of the parameter being measured.
Estas técnicas colorimétricas utilizan mayoritariamente dos métodos de análisis: los visuales y los fotométricos.  These colorimetric techniques mostly use two methods of analysis: visual and photometric.
Los métodos visuales se llevan a cabo en dos pasos: primero se toma un volumen específico de la muestra a analizar, a la que se añade un reactivo que desarrolla un color proporcional a la concentración del elemento a analizar.  The visual methods are carried out in two steps: first a specific volume of the sample to be analyzed is taken, to which a reagent that develops a color proportional to the concentration of the element to be analyzed is added.
Como paso final se compara el color generado en la muestra con una tabla de colores impresa que recoge algunos puntos de referencia. De esta forma, el usuario, por comparación con las referencias, identifica la concentración del elemento bajo análisis.  As a final step, the color generated in the sample is compared with a printed color chart that collects some reference points. In this way, the user, by comparison with the references, identifies the concentration of the element under analysis.
La principal ventaja de ésta técnica es su bajo coste. Su gran inconveniente es la baja precisión, determinada por dos factores: la subjetividad de la lectura de color por parte del usuario, y la baja resolución, dado que normalmente se imprimen en la tabla de referencia unos pocos colores de referencia. Se debe tener en cuenta que entre un 50 y 80% del total del error de medida viene determinado por la lectura subjetiva del color por parte del usuario.  The main advantage of this technique is its low cost. Its great drawback is the low precision, determined by two factors: the subjectivity of the color reading by the user, and the low resolution, since a few reference colors are normally printed on the reference table. It should be taken into account that between 50 and 80% of the total measurement error is determined by the subjective reading of the color by the user.
Los métodos fotométricos, al igual que los visuales, se llevan a cabo en dos pasos. El primero de ellos es exactamente igual que el método anterior. La diferencia viene en el paso final, en el que la medida de color se realiza usando un equipo electrónico que es capaz de analizar el color por métodos ópticos y electrónicos.  Photometric methods, like visual ones, are carried out in two steps. The first one is exactly the same as the previous method. The difference comes in the final step, in which the color measurement is made using electronic equipment that is able to analyze the color by optical and electronic methods.
Éste método ofrece una gran precisión, ya que se elimina la cuantificación subjetiva del color aumentado a su vez la resolución de la medida ya que no se basa en la comparación de unos pocos colores de referencia; sin embargo este método fotométrico requiere la utilización de dispositivos que incorporan elementos ópticos, tales como prismas de difracción, colimadores o filtros ópticos para longitudes de onda específica, lo que encarece considerablemente en coste del equipo.  This method offers great precision, since the subjective quantification of the color increased in turn increases the resolution of the measure since it is not based on the comparison of a few reference colors; However, this photometric method requires the use of devices that incorporate optical elements, such as diffraction prisms, collimators or optical filters for specific wavelengths, which considerably increases the cost of the equipment.
Otro de los inconvenientes de los analizadores fotométricos actuales es que usan cubetas de análisis que se introducen en el equipo. Estas cubetas son manipuladas por el usuario, por lo que fácilmente pueden rayarse o ensuciarse tanto en sus paredes internas como externas, lo que altera las medidas.  Another drawback of current photometric analyzers is that they use analysis cuvettes that are introduced into the equipment. These cuvettes are manipulated by the user, so they can easily be scratched or dirty on both their internal and external walls, which alters the measurements.
Por tanto, la oferta existente de dispositivos para la realización de test colorimétricos está muy polarizada; por un lado los empleados en métodos visuales ofrecen soluciones económicas con prestaciones bajas, mientras que los empleados en métodos fotométricos presentan muy buena precisión a costes bastante altos. Therefore, the existing offer of devices for performing colorimetric tests is very polarized; on the one hand employees in visual methods They offer economical solutions with low performance, while those used in photometric methods have very good accuracy at quite high costs.
Por tanto el problema técnico planteado es el desarrollo de un dispositivo que, siendo de un coste relativamente bajo, mejore sustancialmente los resultados obtenidos respecto a los métodos visuales.  Therefore, the technical problem raised is the development of a device that, being of relatively low cost, substantially improves the results obtained with respect to visual methods.
Descripción de la invención Description of the invention
El dispositivo de la invención presenta unas características, orientadas a realizar la cuantificación del parámetro a medir, mediante la medida del color de una muestra liquida, en la que, al igual que en las técnicas descritas, se habrá añadido previamente un reactivo específico.  The device of the invention has characteristics, aimed at quantifying the parameter to be measured, by measuring the color of a liquid sample, in which, as in the techniques described, a specific reagent will have been previously added.
De acuerdo con la reivindicación primera, este dispositivo comprende: According to claim one, this device comprises:
- una carcasa que se prolonga en una sonda estanca y transparente destinada a introducirse en el líquido a analizar y que presenta, al menos, una primera cavidad destinada a introducirse en el líquido a analizar, - a housing that extends into a sealed and transparent probe intended to be introduced into the liquid to be analyzed and which has at least a first cavity intended to be introduced into the liquid to be analyzed,
- una superficie de reflexión, alojada en la segunda cavidad,  - a reflection surface, housed in the second cavity,
- un emisor de luz alojado en la primera cavidad para la proyección de luz, a través del líquido contenido en la cámara intermedia hacia la superficie de reflexión, - a light emitter housed in the first cavity for the projection of light, through the liquid contained in the intermediate chamber towards the reflection surface,
- un sensor de color alojado en la primera cavidad, que recoge la luz proyectada por el emisor de luz a través del líquido contenido en la cámara intermedia y reflejada en la superficie de reflexión y la convierte en una señal eléctrica procesable, - a color sensor housed in the first cavity, which collects the light projected by the light emitter through the liquid contained in the intermediate chamber and reflected on the reflection surface and converts it into a processable electrical signal,
- una unidad de alimentación,  - a power unit,
- una unidad de control para el procesado de las señales proporcionadas por el sensor de color y el almacenaje de datos,  - a control unit for processing the signals provided by the color sensor and data storage,
- unas entradas de usuario para el manejo del dispositivo y,  - user inputs for device operation and,
- una pantalla de visualización de los parámetros obtenidos.  - a display screen of the parameters obtained.
Este dispositivo proporciona unas importantes ventajas de uso entre las que cabe destacar: la medida de color del líquido se realiza por inmersión de una sonda dentro del líquido a medir, de forma que el líquido acceda a una cámara intermedia, lo que posibilita el uso del dispositivo sin utilizar cubetas exteriores, empleadas en otros métodos fotométricos estándar; la medida de color del líquido se realiza por reflexión de la luz emitida contra una superficie que funciona como fondo de reflexión; la medida de color se realiza de forma relativa, caracterizando la lectura del sensor frente a diferentes patrones conocidos y comprobando la lectura de colores; la medida del color resultante se realiza mediante la interpretación de uno o más canales de color. R.G.B. de ésta forma se pueden hacer medidas complementarias al canal principal, lo que permite obtener información adicional de la muestra. This device provides some important advantages of use among which it is worth highlighting: the color measurement of the liquid is carried out by immersion of a probe into the liquid to be measured, so that the liquid accesses an intermediate chamber, which allows the use of the device without using external cuvettes, used in other standard photometric methods; the color measurement of the liquid is made by reflection of the light emitted against a surface that functions as a reflection background; The color measurement is performed in a relative way, characterizing the sensor reading against different known patterns and checking the color reading; the resulting color measure It is done by interpreting one or more color channels. In this way, RGB measures can be made complementary to the main channel, which allows obtaining additional information from the sample.
En lo que se refiere a su utilización, este dispositivo presenta una gran sencillez de uso, ya que basta con sumergir la sonda en el líquido, de forma que éste ocupe completamente una cavidad intermedia situada entre sensor y la superficie de reflexión y encender el emisor de luz durante el tiempo suficiente para que se ilumine la cavidad óptica de medida. Mediante esta simple operativa, el sensor de color detecta la luz reflejada en una superficie de reflexión. Al haber pasado esta luz a través del líquido a medir, el contenido espectral de la luz reflejada es el mismo que el del líquido bajo medida.  Regarding its use, this device has a great simplicity of use, since it is enough to submerge the probe in the liquid, so that it completely occupies an intermediate cavity located between the sensor and the reflection surface and turn on the emitter of light for long enough for the optical measurement cavity to illuminate. Through this simple operation, the color sensor detects the light reflected on a reflection surface. Having passed this light through the liquid to be measured, the spectral content of the reflected light is the same as that of the liquid under measure.
Cabe mencionar que la superficie de reflexión puede estar en contacto con el líquido, fuera de la primera cavidad, o encontrarse alojada en una segunda cavidad de la sonda. En este segundo caso, la cámara intermedia para el acceso del líquido queda dispuesta entre la primera y la segunda cavidad de la sonda.  It should be mentioned that the reflection surface may be in contact with the liquid, outside the first cavity, or be housed in a second cavity of the probe. In this second case, the intermediate chamber for liquid access is disposed between the first and second cavity of the probe.
Este dispositivo también aporta unas ventajas en lo que se refiere al método de medida:  This device also provides advantages in terms of the measurement method:
La medida se realiza en el líquido alojado en una cámara intermedia situada en el interior del dispositivo, que no es alcanzable por el usuario ni por otros elementos externos que pudieran modificar su funcionamiento. Por tanto el comportamiento caracterizado no se altera con el tiempo ni con la manipulación. Al estar la cámara intermedia integrada en el propio equipo, ésta no debe reponerse nunca, reduciendo así los costes de mantenimiento del equipo.  The measurement is carried out in the liquid housed in an intermediate chamber located inside the device, which is not attainable by the user or by other external elements that could modify its operation. Therefore the characterized behavior is not altered with time or manipulation. Since the intermediate chamber is integrated in the equipment itself, it must never be replaced, thus reducing the maintenance costs of the equipment.
Este dispositivo reduce el coste del equipo, ya que toda la electrónica, está en la misma placa de circuito impreso.  This device reduces the cost of the equipment, since all the electronics are on the same printed circuit board.
Gracias a esto la cámara intermedia en la que se introduce el líquido a analizar puede ser de dimensiones muy reducidas, permitiendo análisis en muestras de líquido más pequeñas (menor gasto de muestra y reactivo). Esto también permite que se realicen análisis dentro de tubos de muestra estrechos que pueden ser de plástico convencional transparente u opaco más económico.  Thanks to this, the intermediate chamber in which the liquid to be analyzed is introduced can be of very small dimensions, allowing analysis in smaller liquid samples (lower sample and reagent costs). This also allows analysis to be performed within narrow sample tubes that can be made of conventional transparent or opaque conventional plastic more economically.
Se realiza una medida de color empleando tres canales de color. R, G y B. lo que permite realizar análisis del color más completos que los fotómetros convencionales, que solo analizan una longitud de onda al mismo tiempo; obteniendo información complementaria sobre el estado del reactivo, colores fuera de rango y otras variables, A color measurement is made using three color channels. R, G and B. allowing more complete color analysis than conventional photometers, which only analyze one wavelength at the same time; getting complementary information on the reagent status, colors out of range and other variables,
No se utilizan elementos mecánicos, ni ópticos, para la medida de color a diferencia de la mayoría de los fotómetros convencionales que utilizan elementos ópticos como prismas de difracción, colimadores o filtros ópticos para longitudes de onda específicas. En esta invención se utilizan sensores ópticos con filtros de longitud de onda integrados, como los sensores RGB. Esto permite una reducción muy importante de costes. El sistema de medida es muy robusto. Las medidas de color dependen, básicamente de la distancia y alineación entre el emisor/receptor y la superficie reflectora. Esta distancia no puede alterarse dada la construcción de la sonda.  No mechanical or optical elements are used for color measurement unlike most conventional photometers that use optical elements such as diffraction prisms, collimators or optical filters for specific wavelengths. Optical sensors with integrated wavelength filters, such as RGB sensors, are used in this invention. This allows a very important cost reduction. The measurement system is very robust. The color measurements depend basically on the distance and alignment between the emitter / receiver and the reflecting surface. This distance cannot be altered given the construction of the probe.
Dependiendo de la precisión requerida pueden utilizarse diferentes sensores de color con diferentes tecnologías de filtrado óptico.  Depending on the required accuracy, different color sensors with different optical filtering technologies can be used.
El equipo puede utilizarse para hacer medidas indirectas de parámetros químicos en líquidos. Tal y como se ha explicado anteriormente a través de reactivos químicos, bien para medida absoluta de colores en líquidos con otros fines como control de calidad, control de producción, regulación de procesos, etc  The equipment can be used to make indirect measurements of chemical parameters in liquids. As explained above through chemical reagents, either for absolute measurement of colors in liquids for other purposes such as quality control, production control, process regulation, etc.
Algunas aplicaciones pueden requerir de compensación de temperatura de la señal de salida del sensor de color. Para esto puede incluirse un sensor de temperatura cerca del sensor de color y se puede compensar la señal del sensor vía hardware o software.  Some applications may require temperature compensation of the output signal of the color sensor. For this, a temperature sensor can be included near the color sensor and the sensor signal can be compensated via hardware or software.
En aquellas aplicaciones en las que la precisión requerida sea muy alta puede modificarse el diseño de la cámara óptica para evitar totalmente la entrada de luz externa en ella.  In those applications in which the required precision is very high, the design of the optical camera can be modified to totally prevent external light from entering it.
Para evitar la entrada de luz desde el exterior en la cámara óptica también pueden utilizarse filtros mecánicos (rejillas) en la entrada de líquido de la cámara.  To prevent the entry of light from the outside into the optical chamber, mechanical filters (grilles) can also be used in the liquid inlet of the chamber.
Las características de la invención, recogidas en las reivindicaciones adjuntas, se comprenderán con mayor facilidad a la vista del ejemplo de realización mostrado con carácter ilustrativo y no limitativo, en las figuras que se describen a continuación. Descripción de las figuras. The features of the invention, set out in the appended claims, will be more readily understood in view of the exemplary embodiment shown in an illustrative and non-limiting manner, in the figures described below. Description of the figures.
- La figura 1 muestra una vista en perspectiva de un ejemplo de realización de la invención. - La figura 2 muestra una vista esquemática de perfil del dispositivo de la figura anterior, seccionado por un plano vertical.  - Figure 1 shows a perspective view of an embodiment of the invention. - Figure 2 shows a schematic profile view of the device of the previous figure, sectioned by a vertical plane.
- La figura 3 muestra un detalle ampliado del extremo de la sonda, seccionado por un plano vertical, para permitir la observación de la cámara intermedia y de los elementos alojados en las dos cavidades interiores.  - Figure 3 shows an enlarged detail of the end of the probe, sectioned by a vertical plane, to allow observation of the intermediate chamber and the elements housed in the two interior cavities.
- La figura 4 muestra un diagrama de bloques general, con los diferentes elementos funcionales del dispositivo de la invención.  - Figure 4 shows a general block diagram, with the different functional elements of the device of the invention.
- La figura 5 muestra un diagrama de bloques de la unidad de control.  - Figure 5 shows a block diagram of the control unit.
- La figura 6 muestra un diagrama de bloques del emisor de luz.  - Figure 6 shows a block diagram of the light emitter.
- La figura 7 muestra un diagrama de bloques de la unidad de alimentación del dispositivo.  - Figure 7 shows a block diagram of the device power unit.
Realización preferente de la invención Preferred Embodiment of the Invention
En el ejemplo de realización mostrado en las figuras adjuntas, el dispositivo de la invención comprende una carcasa (1 ) que se prolonga en una sonda estanca y transparente destinada a introducirse en el líquido a analizar y que presenta una primera cavidad (2) y una segunda cavidad (3) entre las cuales se encuentra definida una cámara intermedia (4), abierta, para el acceso del líquido a analizar.  In the example of embodiment shown in the attached figures, the device of the invention comprises a housing (1) that extends into a sealed and transparent probe intended to be introduced into the liquid to be analyzed and which has a first cavity (2) and a second cavity (3) among which an open intermediate chamber (4) is defined, for the access of the liquid to be analyzed.
En la primera cavidad (2) se encuentran alojados un emisor de luz (5) para la proyección de luz, a través del líquido contenido en la cámara intermedia (4) hacia una superficie de reflexión (6) alojada en la segunda cavidad (3), y un sensor de color (7) que recoge la luz proyectada por el emisor de luz (5) a través del líquido contenido en la cámara intermedia (4) y reflejada en la superficie de reflexión (6), convirtiéndola en una señal eléctrica procesable.  In the first cavity (2) a light emitter (5) for the projection of light is housed, through the liquid contained in the intermediate chamber (4) towards a reflection surface (6) housed in the second cavity (3 ), and a color sensor (7) that collects the light projected by the light emitter (5) through the liquid contained in the intermediate chamber (4) and reflected in the reflection surface (6), converting it into a signal Processable electrical
En una realización preferente la sonda del dispositivo presenta un diámetro inferior a 25 milímetros, lo que permite la medida de color dentro de las cubetas convencionales, ampliamente utilizadas en este campo.  In a preferred embodiment, the probe of the device has a diameter of less than 25 millimeters, which allows the measurement of color within conventional cuvettes, widely used in this field.
El emisor de luz (5) está conformado por un diodo LED (51 ) conectado a través de una fuente de corriente constante (52) con un regulador de tensión (53). La superficie de reflexión (6) alojada en la segunda cavidad (3) de la sonda está conformada en un material no absorbente de luz y preferentemente de color blanco para permitir que la luz se refleje sin distorsión de ningún color. The light emitter (5) is made up of an LED diode (51) connected through a constant current source (52) with a voltage regulator (53). The reflection surface (6) housed in the second cavity (3) of the probe is formed of a non-light absorbing material and preferably white in order to allow the light to reflect without distortion of any color.
En una realización de la invención el sensor de color (7), conectado a una unidad de control (8) encargada del procesado de las señales proporcionadas por el sensor de color (7) y del almacenaje de datos. Comprende un sensor RGB, LDR u elemento equivalente de electrónica comercial,  In one embodiment of the invention the color sensor (7), connected to a control unit (8) responsible for processing the signals provided by the color sensor (7) and data storage. It comprises an RGB sensor, LDR or equivalent element of commercial electronics,
El dispositivo comprende adicionalmente una unidad de alimentación (9) eléctrica, unas entradas de usuario (10) para el manejo del dispositivo, una pantalla de visualizacion (1 1 ) de los parámetros obtenidos y unos puertos de comunicaciones (12) para la conexión eventual del dispositivo con un ordenador externo.  The device additionally comprises an electric power supply unit (9), user inputs (10) for operating the device, a display screen (1 1) of the parameters obtained and communication ports (12) for eventual connection of the device with an external computer.
La unidad de control (8) comprende un procesador (81 ), una memoria (82) con los datos de calibración para el almacenaje de datos referentes al comportamiento del dispositivo de medida ante diferentes estímulos ópticos para la estimación de la concentración de cualquier parámetro a través de puntos de referencia, y una memoria (83) de programa. Esta unidad de control (8) caracteriza la lectura del sensor de color (7) frente a diferentes patrones conocidos y comprueba la lectura de colores, realizando la visualizacion de los parámetros obtenidos en la pantalla de visualizacion (12).  The control unit (8) comprises a processor (81), a memory (82) with the calibration data for the storage of data relating to the behavior of the measuring device before different optical stimuli for estimating the concentration of any parameter a through reference points, and a program memory (83). This control unit (8) characterizes the reading of the color sensor (7) against different known patterns and checks the reading of colors, making the visualization of the parameters obtained in the display screen (12).
La unidad de alimentación (9) comprende unas pilas, baterías recargables o conexión a la red eléctrica (91 ), una protección (92) contra conexión inversa y un regulador (93).  The power unit (9) comprises batteries, rechargeable batteries or connection to the mains (91), a protection (92) against reverse connection and a regulator (93).
En la realización mostrada la pantalla de visualizacion (12) está constituida por un display LCD.  In the embodiment shown, the display screen (12) is constituted by an LCD display.
La sonda dispone de un indicador (13) del nivel mínimo de inmersión en el líquido a analizar, con el fin de evitar una inmersión insuficiente en el líquido y la obtención de errores de medida.  The probe has an indicator (13) of the minimum level of immersion in the liquid to be analyzed, in order to avoid insufficient immersion in the liquid and obtaining measurement errors.
La medida del color del líquido debe hacerse en un tiempo suficiente para que el sensor de color (7) sea capaz de detectar la luz recibida. El tiempo mínimo depende de la tecnología del sensor de color (7). Para los sensores semiconductores, suele ser de 1 a 10 milisegundos, para los sensores LDR puede ser mayor.  The measurement of the color of the liquid must be done in a time sufficient for the color sensor (7) to be able to detect the received light. The minimum time depends on the color sensor technology (7). For semiconductor sensors, it is usually 1 to 10 milliseconds, for LDR sensors it can be higher.
Para la determinación de la concentración de parámetros en una muestra, debe realizarse previamente una calibración del dispositivo, exponiendo la sonda de medida a diferentes concentraciones del elemento a medir a las que se ha añadido el reactivo de medida. Los resultados son almacenados en una memoria (82) para su posterior comparación con el resto de medidas. For the determination of the concentration of parameters in a sample, a calibration of the device must be carried out previously, exposing the measuring probe to different concentrations of the element to be measured at which it has been Measurement reagent added. The results are stored in a memory (82) for later comparison with other measures.
La calibración o caracterización del comportamiento permite compensar los posibles efectos de reflexión o refracción dentro de la cámara intermedia (4) de medida.  The calibration or characterization of the behavior makes it possible to compensate for possible reflection or refraction effects within the intermediate measuring chamber (4).
Si bien la caracterización se realiza en todo el intervalo de medida, la resolución de la medida puede ser mucho mayor ya que al tener el comportamiento caracterizado se pueden interpolar puntos intermedios.  Although the characterization is carried out over the entire measurement range, the resolution of the measurement can be much greater since having the characterized behavior can interpolate intermediate points.
En la realización mostrada las entradas de usuario (10) están representadas por una tecla de encendido/apagado, una tecla de selección y una tecla de test.  In the embodiment shown the user inputs (10) are represented by an on / off key, a selection key and a test key.
Cualquiera de estas teclas puede servir también para realizar funciones de calibración o ajuste del equipo. Por ejemplo, el ajuste de cero del equipo antes de realizar una medida.  Any of these keys can also be used to perform calibration or equipment adjustment functions. For example, zero adjustment of the equipment before making a measurement.
La tecla de selección permite elegir el parámetro a analizar. Una vez seleccionado, al pulsar la tecla test se analiza el color del líquido, se analiza el color y se presenta el resultado de la medida en la pantalla de visualización (1 1 ) o el display LCD.  The selection key allows you to choose the parameter to analyze. Once selected, pressing the test key analyzes the color of the liquid, the color is analyzed and the measurement result is displayed on the display screen (1 1) or the LCD display.
En una realización preferente la superficie de reflexión (6) es de color blanco; no obstante podría ser una superficie de cualquier otro color si se desea hacer una medida en un espectro más estrecho.  In a preferred embodiment the reflection surface (6) is white; however, it could be a surface of any other color if a measurement is desired in a narrower spectrum.
Finalmente cabe mencionar que los puertos de comunicación (12) permiten la conexión del dispositivo con un ordenador para actualizar el programa del equipo, cargar programas adicionales, o descargar las medidas obtenidas.  Finally, it should be mentioned that the communication ports (12) allow the connection of the device with a computer to update the equipment program, load additional programs, or download the measures obtained.
Una vez descrita suficientemente la naturaleza de la invención, así como un ejemplo de realización preferente, se hace constar a los efectos oportunos que los materiales, forma, tamaño y disposición de los elementos descritos podrán ser modificados, siempre y cuando ello no suponga una alteración de las características esenciales de la invención que se reivindican a continuación.  Once the nature of the invention has been sufficiently described, as well as a preferred embodiment, it is stated for the appropriate purposes that the materials, shape, size and arrangement of the described elements may be modified, provided that this does not imply an alteration. of the essential features of the invention that are claimed below.

Claims

REIVINDICACIONES
1 . - Dispositivo para la medición de color en líquidos; caracterizado porque comprende:  one . - Device for measuring color in liquids; characterized in that it comprises:
una carcasa que se prolonga en una sonda estanca y transparente destinada a introducirse en el líquido a analizar y que presenta, al menos, una primera cavidad destinada a introducirse en el líquido a analizar,  a housing that extends into a sealed and transparent probe intended to be introduced into the liquid to be analyzed and which has at least a first cavity intended to be introduced into the liquid to be analyzed,
una superficie de reflexión dispuesta fuera de la primera cavidad y distanciada lateralmente de dicha primera cavidad, encontrándose definida entre la superficie de reflexión y la primera cavidad una cámara o zona intermedia para el acceso del líquido a analizar,  a reflection surface arranged outside the first cavity and laterally spaced from said first cavity, a chamber or intermediate zone being defined between the reflection surface and the first cavity for the access of the liquid to be analyzed,
un emisor de luz alojado en la primera cavidad para la proyección de luz, a través del líquido situado en la cámara intermedia hacia la superficie de reflexión,  a light emitter housed in the first cavity for the projection of light, through the liquid located in the intermediate chamber towards the reflection surface,
un sensor de color alojado en la primera cavidad, que recoge la luz proyectada por el emisor de luz a través del líquido contenido en la cámara intermedia y reflejada en la superficie de reflexión y la convierte en una señal eléctrica procesable,  a color sensor housed in the first cavity, which collects the light projected by the light emitter through the liquid contained in the intermediate chamber and reflected on the reflection surface and converts it into a processable electrical signal,
una unidad de alimentación,  a power unit,
una unidad de control para el procesado de las señales proporcionadas por el sensor de color y el almacenaje de datos,  a control unit for processing the signals provided by the color sensor and data storage,
unas entradas de usuario para el manejo del dispositivo y  user inputs for device management and
- una pantalla de visualización de los parámetros obtenidos. - a display screen of the parameters obtained.
2. - Dispositivo, según la reivindicación 1 , caracterizado porque la sonda comprende una segunda cavidad en la que se encuentra alojada la superficie de reflexión. 2. - Device according to claim 1, characterized in that the probe comprises a second cavity in which the reflection surface is housed.
3.- Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque comprende unos puertos de comunicaciones para la conexión eventual del dispositivo con un ordenador externo. 3. Device according to any of the preceding claims, characterized in that it comprises communication ports for the eventual connection of the device with an external computer.
4.- Dispositivo, según la reivindicación 1 , caracterizado porque el emisor de luz está constituido por un LED conectado a un regulador de tensión a través de una fuente de corriente constante para la emisión de la misma intensidad de luz, independientemente de las variaciones de tensión de entrada. 4. Device according to claim 1, characterized in that the light emitter is constituted by an LED connected to a voltage regulator through a constant current source for the emission of the same light intensity, regardless of the variations of input voltage
5. - Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque la pantalla de visualización está constituida por un display LCD. 5. - Device according to any of the preceding claims, characterized in that the display screen is constituted by an LCD display.
6. - Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque el sensor de color es un sensor RGB 6. - Device according to any of the preceding claims, characterized in that the color sensor is an RGB sensor
7. - Dispositivo, según cualquiera de las reivindicaciones 1 a 5, caracterizado porque el sensor de color es un sensor LDR. 7. - Device according to any of claims 1 to 5, characterized in that the color sensor is an LDR sensor.
8.- Dispositivo, según cualquiera de las reivindicaciones 1 a 5, caracterizado porque el sensor de color está constituido por fotodiodos 8. Device according to any of claims 1 to 5, characterized in that the color sensor consists of photodiodes
9. - Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque la unidad de control comprende un microcontrolador o elemento capaz de realizar un procesado analógico o digital de la información. 9. - Device according to any of the preceding claims, characterized in that the control unit comprises a microcontroller or element capable of performing an analog or digital processing of the information.
10. - Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque la unidad de control comprende una memoria para el almacenaje de un programa de gestión. 10. - Device according to any of the preceding claims, characterized in that the control unit comprises a memory for the storage of a management program.
1 1 . - Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque la unidad de control comprende una memoria de datos de calibración para el almacenaje de datos referentes al comportamiento del dispositivo de medida ante diferentes estímulos ópticos para la estimación de la concentración de cualquier parámetro a través de puntos de referencia. eleven . - Device, according to any of the preceding claims, characterized in that the control unit comprises a calibration data memory for the storage of data relating to the behavior of the measuring device before different optical stimuli for estimating the concentration of any parameter through of reference points.
12. - Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque la sonda dispone de un indicador del nivel mínimo de inmersión en el líquido a analizar. 12. - Device according to any of the preceding claims, characterized in that the probe has an indicator of the minimum level of immersion in the liquid to be analyzed.
13. - Dispositivo, según cualquiera de las reivindicaciones anteriores, caracterizado porque la superficie de reflexión alojada en la segunda cavidad de la sonda esta conformada en un material no absorbente de luz. 13. - Device according to any of the preceding claims, characterized in that the reflection surface housed in the second cavity of the probe is formed of a non-light absorbing material.
PCT/ES2011/070235 2010-05-01 2011-04-07 Device for measuring colour in liquids WO2011138483A1 (en)

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US5652810A (en) * 1996-05-09 1997-07-29 The United States Of America As Represented By The Secretary Of The Air Force Fiber optic sensor for site monitoring
US6113858A (en) * 1998-01-26 2000-09-05 Tang; Ruey-Long Monitor with in-situ optical probe for continuous concentration measurements
US20040086215A1 (en) * 2002-11-04 2004-05-06 Mark Salerno Sampling end for fiber optic probe
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