WO1994014039A1

WO1994014039A1 - Colour quality control method, structure therefor and use thereof for finding a shade to be duplicated

Info

Publication number: WO1994014039A1
Application number: PCT/FR1993/001213
Authority: WO
Inventors: Jean-Pierre Guillemin
Original assignee: Guillemin Jean Pierre
Priority date: 1992-12-09
Filing date: 1993-12-09
Publication date: 1994-06-23
Also published as: FR2698982B1; FR2698982A1

Abstract

A method using a database (BD) accessed via a videotex network by the various professionals (PI) involved in the process of imparting a desired colour to a substrate, and containing various recorded features of one or more dyed materials (MC) from which other dyed materials may be prepared, as well as various application protocols and formulae. According to the method, (a) each PI measures the colour of a sample prepared under predetermined conditions (CD) from one or more of the dyed materials (MC); (b) each PI enters (23, 34) into the database (BD) the identification reference of said colour as well as the above measurements in order to check that said measurements and the corresponding recorded values match; (c) when a match is found, the database (BD) delivers a match confirmation (24, 24', 36), and when a match is not found, (a) the desired correction (40) is set under said predetermined conditions (CD), (b) said correction (26; 27, 28) is entered into the database (BD), and (c) said correction is taken into account by the database (BD) in any subsequent delivery, by said database and on request, for said predetermined conditions (CD), of a similar or related application protocol and/or formula (29); whereby the method highlights any detected mismatch and provides suitable correcting means at all stages in the process.

Description

Color quality assurance process, corresponding structure and use in finding a shade to match.

The present invention relates to a method for assuring color quality, that is to say in short of the visual agreement between the desired color for a colored material and the color actually obtained at the end of the production of a formulated mixture and / or application.

There are international "ISO 9000" management and quality assurance standards and the process according to the invention can apply such standards, without this being limiting.

Different professionals are involved, in a chain, in the process of giving a substrate a desired color. These different professionals, listed below, correspond to the "conceptual model" to which ISO 9000 standards refer in the definition they give of the concept of "quality loop":

"conceptual model of the interdependent activities which exert their influence on the quality of a product or service throughout the phases which go from the identification of the needs until the evaluation of their satisfaction". From upstream to downstream, these professionals are:

- producers of basic materials, ie producers of pigments, resins and various adjuvants and solvents;

- producers of basic products, i.e. colored materials already having a specific destination, such as paints, inks, plastics, etc., basic products which are intended to be mixed between them to get any desired shade;

- the designers of colors / products, that is to say the designers of mixing formulas and application protocols; - prescribers, who can be architects or decorators for building paints, or stylists for printed works, and which recommend the use of such or such a shade in such or such product chosen by them on color charts, which color charts are made up of illustrations of colors corresponding to "recipes" and to each of which is assigned a reference , it being specified that by "recipe" is meant, for the purposes of obtaining a determined shade, all of the information making it possible to produce mixtures, in defined proportions, of basic products for a determined application, the parameters of which as well defined, affect color;

- producers of colors / products, that is to say professionals who mix, in the proportions indicated to them, the basic products; and finally, - the applicators, that is to say for example the painters, in the case of paints for the building industry, which apply said mixtures according to the application protocol which is indicated to them.

Depending on the type and mode of distribution of basic products, some of the services mentioned above can be grouped together in the activity of the same company.

The color charts which correspond to well defined basic products, available from a determined producer, are fairly reliable, provided that the designer of colors / products is the producer of basic products himself, that the color charts are produced with each product in the range of said producer and that the reproduction of colors on paper is faithful, and unalterable over time. However, we are witnessing a gradual deterioration in the reliability of classic design swatches, in particular because they are more or less precisely matched by many manufacturers and reissued more or less successfully in terms of impression. Added to this is the fact that the composition of basic products has evolved, in particular because certain pigments, the use of which has been banned had to be replaced by others; however, two products can only be strictly identical in color if their qualitative composition is identical. Let us also add that it is not uncommon to see a prescriber use a color chart designed for a type of product, such as inks, for example the Pantone color chart, to choose a shade which should be that of a product of a other type, such as a painting ... Finally, add that the color charts are limited: a color chart rarely shows more than 1000 shades while the eye is able to distinguish more than three million.

As a result, errors accumulate at all stages of the process and it is not surprising that the end result rarely meets expectations. EP-0-319 375 proposes an apparatus for determining the formulation of paint for bodywork repair which comprises means for producing a signal representative of the reflectance of the color to be matched and for calculating a formulation by successive approximations. EP-0 484 564 describes, for its part, a matching method which consists in carrying out measurements on a sample, in transmitting the measurements by telephone to a database for calculation of the formulation capable of leading to the expected shade, to carry out a sample from this formulation, to measure the sample and to transmit the measurements again to the base in order to obtain the corrections to be made to the formulation previously supplied.

Neither of the above-mentioned documents describes or suggests means suitable for assuring color quality in the sense defined above.

The author of the present invention proposed, in his French patent application No. 2 685 769, a computerized color chart which results from the splitting of a color space corresponding to a determined collection of chromatic components for a given application, splitting which results to the definition of fractions of volume section to each of which is assigned a reference, each fraction of volume section corresponding to a shade of the color chart. A database can be formed from the corresponding references and the application proposed in the aforementioned patent application is the correction of the "inter-instrument" error observed when using measuring devices of different brands or even of different models inside the same brand. The present invention aims to ensure color quality by proposing a method which uses a database derived from that mentioned above, accessible to the various professionals of the quality loop via a telematic network, and in which have been recorded. : - different characteristics of one or more colored materials from which other colored materials may be prepared, in particular an identification reference and the colorimetric and coloring power measurement values, and - different formulas and protocols d 'application.

The object of the invention is achieved in that the process according to the invention is characterized in that it consists of: a - having each of the professionals involved measure, and in a manner known per se , the color of a sample prepared, under determined conditions, from one or more of said colored materials b - to be entered by each of said professionals involved, the identification reference of said color as well as said measurements, in said base, for verification of compliance between said measurements and the corresponding recorded values, to the nearest manufacturing tolerances, c - in the event of compliance, to be issued by said base, a confirmation of compliance - in case of non-compliance

. to develop the desired correction, under the same determined conditions,

. to enter the said correction into the database, and

. have said correction taken into account by said base during any subsequent supply, by the latter and on request, for the same determined conditions, of a formula and / or a similar or related application protocol, said sample referred to in point (a) being, according to the professional involved: either a sample taken from a batch of basic product, for the purpose of checking that batch and, if necessary, for the purpose of correcting the recipes using it, or sample of mixture of basic products carried out according to a formula provided by the database in response to a specific request, namely a sample of colored substrate resulting from the application to said substrate, according to a determined application protocol, of a mixture basic products, according to a protocol provided by the database in response to a specific request, thanks to which the process, by implementing an interactive and accessible database to the various professionals likely to be involved, report any discrepancy in compliance and provide the appropriate corrective measures, at all stages of the process.

By determined conditions is meant, for example, the identification of the sample if it is a new batch of basic product, the conditions under which a formulated mixture was produced (nature of the batches of products of base used, particularities of the tinting machine from the producer of colors / products, etc.) or in which an application has been implemented (nature of the undercoat, etc.) If the sample referred to above is a sample taken from a batch of basic product, the control operation may be carried out by the producer of basic product, before shipment, as by the producer of colors / products before first use.

If the sample is a sample of a mixture of basic products carried out according to a formula provided by the database in response to a specific request, it will be a check carried out on a mixture made by the producer of colors / products. .

If the sample is a sample of colored substrate resulting from the application to said substrate, according to a determined application protocol, of a mixture of basic products, this will be a recipe control by the applicator.

In a first embodiment of the invention, said specific request made to the database follows from technical elements previously supplied by said database in response to a pre-request having resulted in a selection from the possibilities of recipes proposed by said base. This pre-request will be formulated by the prescriber from colorimetric measurements, according to a technique known per se, of a shade to be matched.

It may happen that the database does not offer any possibility of a recipe satisfying the pre-request as it stands and, in such a case, the process consists in developing such a recipe - provided that it is technically feasible with the means available - and to enter the corresponding information in the database. This development will be done by a color / product designer.

We understand, from this stage, that any pre-request not finding a "ready-made" solution leads to a study and an enrichment of the database which will benefit other users, enrichment which is done by itself in the sense of market demand. If it appears that the pre-request cannot be technically satisfied from the available means, the database offers the requester an alternative response and / or indicates the reasons for the technical impossibility.

The present invention also relates to a structure for implementing the method. This structure uses a telematic network for access to an interactive database, and it is characterized in that said base defines each color referenced, taking into account a global average colorimetric tolerance normalized, according to the nature of the product (paint, ink, etc.) to be prepared and according to the application procedures used in the field of activity concerned. Preferably, the referenced shades are arranged in a chromatic space so as to be distant from each other by a value equal to twice the average overall color tolerance. A base thus structured, when it is complete, allows for close searches to systematically find a shade close to the shade measured in an overall colorimetric difference less than or equal to the overall average colorimetric tolerance.

We consider in a way that the database has a "step" in the chromatic space and that this step corresponds to the set of tolerances that the envisaged application allows. To establish this step, the production tolerances of the basic products, the production tolerances of the mixtures, the application tolerances, and also the inter-instrument error mentioned above will be taken into account.

Other characteristics and advantages of the invention will emerge from the detailed description below made with reference to the appended drawings which schematize the exchanges between: Figure 1: the producer of basic products, the database and, through it, the designer of colors / products;

Figure 2: the prescriber, the database and, through it, the color / product designer;

Figure 3: the producer of colors / products, the database and, through it, the designer of colors / products; and, Figure 4: the applicator, the database and, through it, the color / product designer

In the description of the figures, the term "database" will be used both to designate the database itself and the central computer which manages it.

It will be noted that the operations of periodic calibration of the measuring and production apparatuses, of diagnosing a possible malfunction of the measuring and production apparatuses and of remote control of these two types of equipment are necessary for quality management. They do not appear in FIGS. 1 to 4 so as not to overload them, but they are nevertheless implemented.

Figure 1 illustrates the interventions of the producer of the basic products, abbreviated PPB, in the process. By means of a telematic terminal, such as a Minitel device or a microcomputer, the PPB connects to an interactive database. It enters this database, according to 59, the reference of each of its basic products, abbreviated as PB, and various measurements and characteristics of said products (reflectance curve, and / or tristimulus, conformity limits, contrast ratio, lightfastness, coloring power, appearance (mat, satin, gloss), mixing recipes, recommended number of coats, recommended shade for the undercoat, indicative sales price, indicative yield, etc.). The designer of colors / products, abbreviated CCP, on the one hand, has the PB supplied by the PPB and, on the other hand, can extract, according to 20, the data from the base he wishes. By carrying out practical tests and measurements on PBs, he can develop additional formulas by mixing PBs in defined proportions, formulas which he then enters, according to 21, in said base. He also studies application protocols for the various formulas, protocols that he enters into the database in the application parameters file, according to 19 (Figure 4).

Subsequently, each time a new batch of a PB is manufactured, the PPB performs a compliance control operation between this batch and the measurement values previously recorded by it in the database (in other words, compliance with the values of the nominal shade and the conformity of the coloring power). To do this, it measures the color and the coloring power of a sample of the batch and sends to the base, according to 61, the reference of the batch and said measurements according to a protocol which is dictated to it by said base. The latter compares the measurements entered by the SCH with those recorded at the origin, assesses the differences in conformity and decides whether the batch is in conformity or not. If the batch is in conformity, this is confirmed to the PPB according to 62. If it is not in conformity, the base triggers an alarm of non conformity which it addresses, on the one hand, according to 63, to a "letter box "of communication with the PPB and, on the other hand, to a" mailbox "of communication with the CCP. These mailboxes are interrogated at regular intervals by their respective recipients. Thus alerted, according to 64, the CCP develops means of correction which will be applied to this particular batch and that it enters, according to 26, in a file of correction means per batch of PB. By application to the data originally recorded in the database of the correction means recorded in the corresponding file, which leads in 22 to data corrected, it is possible to issue, according to 62 ', a certificate of compliance with the PPB.

Figure 2 illustrates the sequence of steps in the process starting from an intervention by a prescriber. This measures the color of a sample to be matched, and by means of a Minitel-type terminal or, better, a microcomputer incorporating or connected to a color screen, it connects to the database. According to 1, he enters his own reference and the measurements in question (as a variant, the colorimetric measuring device can be connected via an appropriate interface to the terminal, thus allowing direct input of the measurements). The base searches, according to 2, for the colors recorded closest to that requested, and the corresponding information is communicated according to line 3. The base then proceeds, according to 4, to sort these colors by product and the list obtained is transmitted, according to 5, to the prescriber. The latter examines this list including, for each shade, all the data entered by the PPB, and the prescriber is assisted in his choice by details such as the color deviations of the shades found in the database compared to the shade measured, evaluated in the form of quantified standard color differences, commented color differences (lighter, more vivid, more yellow, for example) and / or an on-screen illustration of the colors found allowing a visual appreciation of the differences. To take advantage of this last type of assistance, he must naturally have a color screen. The selection of the suitable product can be made on the basis of the properties of each product, appearance, aging conditions, possible treatment of the substrate, etc.

If the prescriber finds a satisfactory choice (line 6), he asks the base, according to line 7, the technical elements available on the product and the color chosen. The data are interrogated, according to 8 and the response, communicated according to 9, is retransmitted to the prescriber according to 10. The latter then drafts the corresponding specifications.

If no proposal received according to 5 satisfies the prescriber (line 11), he enters the keyboard, according to 12, into the communication mailbox, according to 13, with the CCP, a request for a special solution. The CCP studies whether the demand can be satisfied from the basic products whose characteristics have been entered into the database, which leads, according to 14, to an assessment of the feasibility. If this assessment is affirmative, the formula specially designed at the request of the prescriber is entered according to 15 in the database which it thus enriches, and communicated according to 5 'to the prescriber. If, on the other hand, the assessment is negative, the corresponding information is transmitted according to 16 to the base together with a proposal for an alternative solution, which is communicated according to 5 "to the prescriber. Simultaneously, the infeasibility of the shade requested for the requested product is entered, on the one hand, according to 17 in the mailbox communicating with the PPB and, on the other hand, according to 18, in a directory of infeasible shades by product contained in the database .

The PPB is thus warned of unmet market demands, which enables it to develop new basic products to remedy them. When an infeasibility is remedied, the corresponding directory of the database is updated accordingly.

Of course, as we saw with regard to Figure 1, the PAC does not study new formulas only on special requests from prescribers. He can study them spontaneously and enter them into the base according to 21.

Figure 3 illustrates the relationships from the producer of colors / products, abbreviated PCP.

When it receives a new batch of PB, the PCP measures the color and the coloring power and sends to the base, according to 23, the reference of the batch and said measurements according to a protocol which is dictated to it by the base; information inputs by the PCP are checked to determine if they comply with the nominal values as they result according to 22 (Figure 1).

If they are compliant, the base confirms this to the PCP according to 24. If they are not compliant, via the communication mailbox with the CCP, not shown in FIG. 3, the base requests, according to 25, the CCP to develop correction means which will be applied to this particular batch as used by this particular PCP and, according to 26, via the communication mailbox with the PPB, not shown in the figure 3, it reports the anomaly to the PPB.

The correction means thus developed are entered, according to 27, in a corresponding file in the database and applied, according to 28, to the recipe file by shade and by product. It is then confirmed to the PCP, according to 24 ', the conformity of the batch received or more exactly that the measures have been taken so that the PCP can use said batch. When the PCP uses a tinting machine whose flow rate of each base product tank is adjustable remotely, this flow rate can be adjusted from the database according to the specific correction that has been developed for a batch of product basic determined. When the PCP receives an order according to specifications resulting from the implementation of the process illustrated in Figure 2, it interrogates (line 29) the base according to a request which takes into account the desired shade, product and quantity. According to 30, the desired information is extracted from the database, and the extracted information, including a test protocol, is retransmitted according to 31 and 32 to the PCP.

The PCP implements the recipe according to the test protocol, then, according to 33, measures the color of the mixture obtained and sends, according to 34, the corresponding values to the base. This compares the information received with those corresponding to the nominal shade to lead, according to 35, to the phase of evaluation of the tolerance difference. If the deviation is acceptable, a certificate of conformity is issued according to 36. In the opposite case, the base stores, according to 37 the difference in conformity and sends an alarm of non-conformity to the PCP according to 38. This same alarm and the difference are communicated to the CCP according to 39 which exploits the information received and either , according to 40, corrects the recipe and enters the modification according to 28 in the database, either looking for any anomaly that may have occurred either in the control of the batches of PB, or else in the implementation of the recipe.

If the table does not show the possibilities of remote diagnosis on the measuring and possibly mixing devices allowing remote sensing of a fault or a remote verification of equipment calibrations, such possibilities exist.

Figure 4 illustrates the relationships from the applicator. For each new batch of colored product received from the PCP, the applicator measures the color and sends to the base, according to 41, the reference of the batch and said measurements according to a protocol which is dictated to it by said base. The latter checks whether the information entered by the applicator conforms to that which it contains concerning the corresponding nominal shade. If they comply, it confirms this to the applicator according to 42. If they do not comply, it requests, according to 44, the CCP to develop means for correcting application parameters and, according to 45, it signals the PCP anomaly.

The correction means thus developed are entered, according to 46, in a corresponding file in the database and applied to the file of application parameters contained in the database. It is then confirmed to the applicator, according to 42 ', the "conformity" of the batch received or more exactly that measures have been taken so that the applicator can use it in subsequent operations.

The applicator then requests (line 47) the application parameters for this batch of colored product. According to 48, the desired information is extracted from the database, and the extracted information, including a test protocol, is retransmitted according to 49 and 50 to the applicator.

The applicator applies the colored product to a substrate according to the test protocol and the measurement of the shade of the substrate is sent, according to 52, to the base which compares the information received with that corresponding to the nominal shade to succeed, according to 53 , during the tolerance deviation assessment phase. If the deviation is acceptable, a certificate of conformity is issued according to 54. Otherwise, the base, according to 55, stores the compliance gap and sends a non-compliance alarm to the PCP according to 56. This same alarm and the gap are communicated, according to 57, to the CCP which processes the information received and either, according to 58, corrects the application parameters and enters the modification according to 46 in the database, or searches for any anomaly that may have occurred either in the control of the batch of colored product, or in the setting of the application. From the foregoing description, it is understood that control is exercised at all stages of the process and at the level of all professionals, and that the desired corrections are made, as soon as a nonconformity is found. The color quality is thus considerably improved.

For reasons specific to colorimetry, the method according to the invention appears to be the only one capable of ensuring the color quality of a colored production. Among these specific reasons, we can cite: - the absence of primary color standards, - the alteration over time of secondary color standards,

- the inter-instrument error inherent in color measurement devices, - the misuse of "color charts" as colorimetric standards.

Although the aim of the process according to the invention is to propose recipes in each type of basic product in the range of a PPB which have been verified by production and measurement and which can therefore be certified, it is possible to include , in addition, in the database of only calculated recipes (and therefore, not certified, this lack of certification being indicated in the database).

Thus, for example, if a shade has been produced in glossy lacquer and certified, it can be proposed in the base as a matt facade product, by calculation. It is indeed possible to "model" the calculation making it possible to establish the formula of mixture in a type of product from that carried out in another type of product. This "modeling" remains approximate. Naturally, at the request of the prescriber, a calculated formula, not certified, can give rise to the procedure of practical realization and certification. This procedure significantly increases the response capabilities of the database.

Claims

1 - Method for ensuring color quality, that is to say the visual agreement between the desired color for a colored material and the color actually obtained, all along the chain, called "loop of quality ", of the various professionals likely to be involved in the process making it possible to give a substrate a desired color, which process uses a database forming a computerized color chart accessible to the various professionals via a telematic network, and in which were recorded:

- different characteristics of one or more colored materials from which other colored materials may be prepared, in particular an identification reference and the colorimetric and coloring power measurement values, and

- different formulas and application protocols characterized in that it consists of: a - having each of the professionals involved measure, and in a manner known per se, the color of a sample prepared, under determined conditions, at from one or more of said colored materials b - to be entered (59; 1; 23, 34; 41, 52) by each of said professionals involved, the identification reference of said color as well as said measurements, in said base, to verify compliance between said measurements and the corresponding recorded values, to the nearest manufacturing tolerances, c - in the event of compliance, to have issued by said base, a confirmation of compliance (62, 62 '; 24, 24', 36 )

- in case of non-compliance

. to develop the desired correction (64; 40; 58), under the same determined conditions,

. entering said correction (26; 27,28; 46) in the database, and . to have said correction taken into account by said base during any subsequent supply, by the latter and on request, for the same determined conditions, of a formula (29) and / or of an application protocol (47) similar or related, said sample referred to in point (a) being, according to the professional involved: either a sample taken from a batch of basic product, for the purpose of checking said batch and, if necessary, for the purpose of correcting revenue using it, either a sample of mixture of basic products carried out according to a formula provided by the database in response to a specific request, or a sample of colored substrate resulting from the application to said substrate, according to an application protocol determined, of a mixture of basic products, according to a protocol provided by the database in response to a specific request, thanks to which the method, by implementing an interactive database and accessible to the various professionals likely to be involved, reports any deviation in compliance and provides the appropriate means of correction, at all stages of the process.

2 - Method according to claim 1, characterized in that said specific request results from technical elements supplied (10) by said base in response to a pre-request (1, 7) having resulted in a selection from the possibilities of recipes ( 5) proposed by said base.

3 - Process according to claim 2, characterized in that the pre-request is based on colorimetric measurements known per se of a shade to be matched.

4 - Method according to claim 2 or 3, characterized in that it consists, in the event that said base does not offer in the state any possibility of recipe satisfying said pre-request, to develop (13) such a recipe - as long as it is technically feasible with the means available - and to enter (15) the corresponding information in the database and, if said pre-request cannot be technically satisfied using said means, to offer the requester (16, 5 ") an alternative response and / or to him indicate the reasons for the technical impossibility.

5 - Structure for the implementation of the method according to any one of claims 1 to 4, which uses a telematic network for access to an interactive database, characterized in that said base defines each tint referenced, taking into account has a normalized average overall color tolerance, depending on the nature of the product (paint, ink, etc.) to be prepared and according to the application procedures used in the field of activity concerned.

6 - Structure according to claim 5, characterized in that the referenced shades are arranged in a reference chromatic space so as to be distant from each other by a value equal to twice the overall average colorimetric tolerance.

7 - Use of the structure according to claim 5 or 6, in the context of the search, in said database, for a shade identical to a shade to be matched, or a choice of shades closest to the latter , which exist in said base, as well as technical elements allowing the production of a colored product having the desired or chosen shade and application parameters of said colored product.

8 - Use according to claim 7, characterized in that the structure comprises means for viewing on a color screen the shade or shades proposed by said database in response to said search.