DE69726376T2 - Color mixing and control system for an electrostatographic printing machine - Google Patents

Description

BACKGROUND THE INVENTION

This invention relates generally a development system for the generation of colored output images in an electrostatographic printing device and deals in particular with a system for providing a customer-specific color control in one on liquid Development material based, electrostatographic printing system. The color mixing and color control system captures the color of a operational mix of development material made from a mix consists of several basic color components, and controls further the concentrations of the corresponding primary color components, the to fill up of the operative mixture.

It is well known that conventional electrostatographic reproduction processes after suitable adjustment can be used to generate multicolored images. For example can the charged, photo-electrically conductive element of the series after a series of color-separated images that are the primary colors of an input image are exposed to a plurality of color-separated, latent images. Each color separated Picture comes with a complementary Developed development material that contains a primary color or a shade that corresponds to the subtractive complement of the color-separated image, being later all developed, color-separated images to create a multi-colored Output image on top of each other be placed. Thus, a multicolor image is made up of different primary colors or their subtractive complementary grids are formed, which are all mixed up by the eye, creating the visual impression a color image is created.

US-A-4111151 and US-A-4113371 disclose electrostatographic Pressure Equipment, which contain a plurality of developing material supply containers with toner particles previously chosen Color and have a unit in which the toner particles are mixed to be a desired one as a result Color according to the original, straight to receive reproduced document, the concentration of Toner particles in the mixture are automatically regulated.

DE-A-2724776 discloses a process for development electrical latent images, the development with the help of a liquid Developer which contains a mixture of at least two different toners, wherein Hue, saturation and gradation of the color of the mixture by mixing any of different color toners and black / white toners can be controlled.

With the introduction of knowledge of the Advances have been made in electrostatographic technology in multicolor printing also made in the direction of creating so-called "highlight color images", in which independent, different colored, monochrome images are generated on a single output sheet, preferably while of a single work cycle. Likewise, "color dot" or "high fidelity color printing" was developed, whereby a printing system, that is able to generate colored process output images with an additional developer housing is equipped with an additional Color alongside the primary or subtractive colors, which are used to generate the colored process output used. This additional developer housing is used to develop an independent Image with a specific color (color dot printing) or for expansion the color scale of the colored process output (high-fidelity color printing). As such, various concepts have emerged from the conventional electrostatographic imaging techniques developed and originally based on monochrome and / or colored process image production were directed, modified to produce output images of the selected areas that have a different hue than the rest of the document. Applications of the highlight color include the laying of the Emphasis on important information, emphasis on titles and, more generally, the distinction between specific areas of text or other image information.

A specific application of the highlight color process is printing with color selectable by the customer, a very specific highlight color is required. Colors selectable by the customer are typically used for instant identification and recognizing authenticity of a document. The customer is usually very keen that the Color certain color specifications met. For example, the red, with the digitally stylized "X" from Xerox related color is a customer selectable color with a special color Nuance, a special hue and color value. Likewise, the special one Nuance des Orange, associated with Syracuse University, a good example of one selectable by the customer Colour. Even more specific examples of customer-selectable color output can in the area of "customer colors" can be found, which relate specifically to registered, protected colors, like them For example in company logos, authorized letterheads or official seals can be used. The yellow that comes with the goods of Kodak, and that associated with the Hershey goods Browns are good examples of Customer colors in a highlight or color dot printing application certain color standards must meet exactly.

The colors used for standard highlight processes generally did not exactly match the colors that the customer could select. In addition, colors usually selectable by the customer cannot be produced exactly with the help of color halftone process methods, because when using the color halftone process technique the generation of massive image areas with a special color usually leads to differences in the color of the image area. In addition, lines and texts produced with color halftone processes are very susceptible to incorrect positioning of the different color images, which can be expressed in blurring, color differences and other image quality losses.

To the desired color output selectable by the customer to generate, due to the shortcomings mentioned above, the generation of from Customer selectable Colors in electrostatographic printing systems typically by providing a single, pre-mixed composition of development materials, that of a mixture of several in preselected concentrations consists of mixed color toner particles. This Method of mixing several color toners to produce a special one Color development material is analogous to the processes used to make colorful paint or color ink with customer selectable colors to create. With offset printing, for example, an output image is displayed with customer selectable Color created by - in Contrary to printing a plurality of halftone patterns with different primary colors or their complements - a massive picture pattern with a premixed, customer selectable Color printing ink is printed. This concept was, for example im public granted U.S. Patent No. 5,557,393, generally to electrostatographic Printing technology expanded, creating an electrostatic, latent image of a dry powdered developing material that is two or more compatible with each other Contains compositions developed is a customer selectable To generate color output.

The "Xerox Disclosure Journal", Issue 21, No. March 21st 1996, page 155 a development process that has a development case, the one liquid Developer contains which consists of at least two different colored connections, the one with a desired one concentration ratio were mixed in advance to provide customer-specified color images to deliver.

Customer-selectable color printing materials (inks, printing inks and developing materials) can, by determining an exact amount of constituent components of the basic color component that make up a given customer-selectable color material, providing the precisely measured amount of each of the constituent components of the basic color component and thoroughly mixing these color components to be produced. This process is usually facilitated by reference to a color guide or color book that contains hundreds or even thousands of patterns representing different colors, each color pattern being represented as a specific formula of color components. Probably the most common of these color leader Pantone was ^®, Inc. of Moonachie, New Jersey, published. The "Pantone ^® Color Formula Guide" expresses colors using a certified pattern system, and provides a precise formula that is needed to create a specific, customer-selectable color by physically mixing predetermined concentrations of up to four colors from one set of up to 18 main or primary colors. Many colors that cannot be produced by the typical color halftone process methods or even by mixing certain amounts of cyan, magenta, yellow and / or black inks or developing materials can be made accessible by using the Panteone ^® system or other color formula guides of this type become.

Consider the present invention a development system that includes a color mixing and control system, the color value of the development material in a stock reservoir regulated, and the rate of refilling of different color components, which are added to the reservoir can be freely selected can be. By adding and mixing exact amounts on specific development materials from a set of basic color components becomes the actual color of the development material in the reservoir in accordance to the predetermined, chosen Brought color. Through the appropriate control the filling process can also a big Range of customer selectable Color development materials generated and during a very long print job to be kept.

According to a first aspect of the invention, a system for providing a customer selectable color developing material for printing a customer selectable color image area on an output tray in an electrostatographic printing device includes a plurality of developing material supply containers each containing a different colored developing material concentrate corresponding to a basic color component a color matching system, a developing material reservoir to which at least one of said plurality of developing material supply containers is connected to provide an operational supply of developing material with the customer selectable color, a system for systematically dispensing a selected amount of developing material concentrate from at least one selected one of said developing material supply containers to give the operating supply of developing material a selected one To provide a primary color component, a color detection device for monitoring the color of the operative supply of development material, characterized by a control system connected to said detection device for selectively activating said systematic delivery system in response to the measured color of said operational supply of development material, wherein said control system works to do that Provides development material with the customer selectable color by mixing the multitude of different colored development material concentrates.

According to a second point of view The present invention becomes an electrostatographic printing device provided the at least one development subsystem for development at least a portion of an electrostatic image with a liquid developing material with color selectable by the customer includes an image area with a customer selectable Color on an output medium to generate, the subsystem of the first aspect of the present Invention corresponds.

In a third aspect, the present invention includes an electrostatographic printing process in which at least a portion of an electrostatic latent image is developed with a liquid developer material having a customer selectable color, comprising the steps of: providing a plurality of developer material supply containers, each containing a different color developing material concentrate corresponding to a primary color component of a color matching system, optionally providing at least one of the plurality of different colored developing material concentrates to a developing material reservoir to produce an operational supply of developing material with the customer selectable color, systematically dispensing a selected amount Develop material concentrate of a selected primary color component to said development material reservoir, around which said delivering a selected primary color component to the operational supply of developing material, monitoring a color of said operational supply of developing material, systematically delivering a selected amount of developing material concentrate of a selected basic color component to said developing material storage container ( 10 ) in response to the color of said operative supply of development material, and mixing the plurality of different colored development material concentrates to provide said development material with the customer selectable color.

Another aspect of the present Invention may be that the control system is also for mixing one selectable by the customer Color can be used in situ, with approximate amounts of primary or Base color components first placed in the development material container and mixed in it, being constantly monitored and adjusted, until the mixture matches some predetermined optical target properties.

Other aspects of the invention will become apparent as the following description proceeds, also with reference to FIG 1 10, which provides a schematic elevation of an exemplary liquid development material aggregate and an exemplary liquid development material development system that, in accordance with the present invention, combines a color mixing and control system for liquid development materials.

While the present invention is primarily used in the three-level highlight color image may, it will become clear from the following discussion that the color mixing and control system of the present invention can be used just as well in the wide range of pressure equipment and not necessarily for use in a special, single-run electrostatographic Three-level highlight process limited is. In fact, it is desirable that the color mixing and control system of the present invention can be extended to any electrostatographic printing process can, which is provided, an image area with one from the customer selectable To produce color, such as multi-color printing devices, with a subordinate development housing with customer selectable Paint could be fitted as well as pressure equipment, performing ionographic printing processes, or the like. More generally speaking it should be understood that - although the color mixing and control system of the present invention hereinafter in connection with a preferred embodiment the invention is described - the Description of the invention the scope of application of the present Invention is not limited to this preferred embodiment.

Let us now consider 1 4, in which an exemplary apparatus for developing an electrostatic latent image is shown in schematic form using liquid development materials. Normally, an electrostatographic printing device for displaying highlight colors would contain at least two development devices with different liquid development materials in order to develop latent image areas into different, colored, visible images. As an example, in a three-level system such as that described here, a first developing device can be used to develop the positively charged image areas with liquid, black colored development material, while the second developing device can be used to customize the negatively charged image area Developing color. Each different liquid development material includes pigmented toner or marker particles as well as charge control additives and charge directors, all of which are spread through a liquid carrier, the marker particles being charged with a polarity opposite to the polarity of the charged latent image to be developed.

The developing device 1 works primarily to transport the liquid developing material to contact with a latent image or photoreceptor surface, generally through the reference number 100 to be recognized, the marker particles being attracted to the electrostatic latent image by electrophoresis in order to produce a visible, developed image therefrom. As for the development material transport and application process, the basic types of operation of each of the development devices are basically identical to each other, and that in 1 The developing device shown is only one of many known devices that can be used to apply liquid developing material to the photoelectrically conductive surface. It should be understood that the basic development system that combines the mixing and control systems of the present invention can take various forms, such as the systems described in U.S. Patents 3,357,402, 3,618,552, 4,733,273, 4,883 .018, 5.270.782 and 5.355.201. Such development systems can be used in a multi-color electrophotographic printing machine, a machine with highlight colors or in a monochromatic printing machine.

Before describing the color mixing and control system of the present invention, let us focus on the development process: in the exemplary development device 1 becomes liquid development material from a reservoir 10 with the help of an aggregate 20 for liquid development material to the latent image on the photoreceptor 100 transported. reservoir 10 works as a storage container for providing an operational solution of liquid development material comprising liquid carriers, a charge director assembly and toner material which, in the case of use of the present invention, includes a mixture of different colored brand particles with customer selectable colors. According to the present invention, a variety of interchangeable dispensers 15A - 15Z , each of which contains a concentrated supply of branded particles and carrier liquid according to a basic color component in a color matching system, in connection with the operative storage container 10 provided to replenish the liquid development material stored therein, as described below.

The exemplary development material aggregate 20 includes a housing 22 that has an elongated opening 24 has that extends along its longitudinal axis such that it extends substantially transversely to the surface of the photoreceptor 100 located along the direction of movement of the same as indicated by the arrow 102 marked. The opening 24 is with an inlet duct 26 connected, which in turn via transport channel 18 with the container 10 connected is. transport channel 18 works in connection with opening 24 as a travel path for liquid development materials coming from the container 10 transported away, and also describes an application area for developing material, in which the liquid developing material can flow undisturbed to the surface of the photoreceptor belt 100 to touch and develop a latent image on it. Liquid development material is thus removed from the reservoir 10 through at least one inlet duct 26 to the unit 20 pumped or otherwise conveyed that the liquid developing material from the elongated opening 24 flows and in contact with the surface of the photoreceptor belt 100 occurs. In addition, an overflow drainage channel (not shown) covering the opening 24 partially enclosed, may be provided to accommodate excessive development material that is not intended to be carried over to the photoreceptor surface during development. Such an overflow drainage channel would have a drainage channel 28 be connected to return excessive or unrelated material to the container 10 or sent to a waste pump where the liquid development material is preferably collected and its individual components can be recycled for later use.

Slightly below (towards the movement of the photoreceptor surface 100 ) and adjacent to the development material aggregate 20 there is an electrically biased development roller 30 whose peripheral surface is a short distance from the surface of the photoreceptor 100 lies. The development scooter 30 rotates in a direction opposite to the movement of the photoreceptor surface so as to exert a considerable thrust on the thin layer of liquid developing material which is in the area of the slot between the developing roller 30 and the photoreceptor 100 located, and to minimize the thickness of the liquid developing material on the surface of the receptor. This pushing force removes a predetermined amount of excessive liquid developing material from the surface of the photoreceptor and conveys this excessive developing material towards the developing material assembly 20 , The excessive developing material eventually drips from the rotating metering roller to the container 10 or a waste pump (not shown) to be collected. To maintain an electrical voltage on the metering roller 30 with a selected polarity and strength also becomes a DC power supply 35 Provided so that image areas of the electrostatic latent image on the photoelectrically conductive surface attract brand particles from the development material and thus develop the electrostatic latent image. This electrophoresis development process minimizes the existence of branded particles in background areas and maximizes the delivery of branded particles in image areas on the photoreceptor.

During the process, liquid developing material is directed towards the photoreceptor 100 which promotes the gap between the surface of the photoreceptor and the aggregate for liquid developing material 20 crowded. If the strap 100 itself in the direction of the arrow 102 moves, part of the moves liquid developing material in contact with the photoreceptor together with the belt towards the developing roller 30 where branded particles from the liquid developing material are attracted to the electrostatic latent image areas on the photoreceptor. The development role 30 also measures a predetermined amount of liquid developing material that is on the photoreceptor surface of the belt 100 sticks, and works as a seal to prevent non-liquid developing material from being carried away by the photoreceptor.

Applying development material to the photoelectrically conductive surface naturally decimates the total amount of operative solution of development material in the feed container 10 , In the case of liquid development materials, branded particles are consumed in the image areas; Carrier fluid is consumed in the image areas (trapped by brand particles) and in the background areas and can also be decimated due to evaporation; and charge judge is consumed in the image areas (trapped in the carrier liquid), in the image areas by absorption by the marker particles and in background areas. In everyday practice, the container 10 therefore, if necessary, constantly replenished by adding development material or selected components thereof, in the case of liquid development materials, for example by adding liquid carrier, marker particles and / or charge straighteners to the container 10 , Since the total amount of each of the components making up the developing material used to develop the image can vary as a function of the area of the developed image areas and the background areas of the latent image on the photo-conductive surface, the specific amount of each of the components of the liquid changes Development material in the hopper 10 must be added with every development cycle. For example, a developed image, which largely consists of a printed image area, will cause a greater consumption of branded particles and / or charge directors from the development material container than, in comparison, a developed image, which consists to a small extent of a printed image area.

It is known in the art that, therefore, during the fill rate of the liquid carrier component of the liquid developing material, simply by monitoring the level of the liquid developer in the supply container 10 can be controlled, the fill rate of the branded particles and / or the charge director must be controlled in a further developed manner in order to obtain the correct predetermined concentration, so that the marker particles and the charge director in the in the feed container 10 stored operational solution may work properly (although concentration may vary over time due to changes in work parameters). In the patent literature and elsewhere, systems for systematically replenishing individual components that make up the liquid development material (liquid carrier, marker particles and / or charge judge) were revealed when they came out of the container during the development process 10 disappear. For example, consider the publicly issued "US Patent Application Serial", No. 08 / 551,381 and the sources cited therein.

However, the present invention contemplates a developer material replenishment system capable of systematically replenishing individual color components that make up a customer selectable developer material color composition. As such, the replenishment system of the present invention includes a variety of different colored concentrate dispensers 15A . 15B . 15C , ..., 15Z , of which at least one pair has an associated valve of the series 16A . 16B . 16C , ..., 16Z or another suitable feed control device is connected to the operative feed container. Preferably, each dispenser contains a developer concentrate from a known primary or primary color component used in a given color matching system. Understandably, any donor can choose from a variety of dispensers with the container 10 connected, as well as only selected donors to the container 10 can be connected. For example, under certain circumstances, such as space constraints or cost constraints, it may be desirable to only the donors 15A . 15B and 15C to use, which results in a simplified color matching system.

In a specific embodiment, the refill system includes sixteen dispensers, each dispenser providing a unique primary color development material that corresponds to one of the sixteen primary or constituent colors of the ^Pantone® color matching system, so that color formulas provided by this system can be conveniently used to over one thousand produce desired colors in a printing environment with customer-selectable colors and nuances. When using this system, only two different development materials can be used, for example from the donation containers 15A and 15B , in container 10 can already be combined in such a way that the color gamut of colors that can be selected by the customer can be expanded far beyond the number of colors that can be achieved by halftone techniques, or even the number of colors that can be achieved by mixing only yellow, magenta , cyan and black development materials.

An essential component for mixing and controlling the colored development material in the present invention is a mixture control system. That is, it is because there are various components of the development material poured or mixed into containers 10 can develop at different rates, a mix control 42 provided for the colors selectable by the customer, for appropriate amounts of each of the colored development materials in the feed containers 15A . 15B ... or 15Z to determine which may be in the hopper 10 must be added, and to add each of these appropriate amounts of development material in a controlled manner. The control 42 can be designed in the manner of any conventional microprocessor-based storage and processing device known in the art.

The approach provided by the color mixing and control system of the present invention includes a detection device 40 , for example an optical sensor for monitoring the color of the liquid development material in the container 10 , It makes sense that - although a spectrophotometric approach to color detection can enable very precise color measurements - due to the high costs and computational requirements, these advantages are not as significant compared to a simpler technology. Therefore, the preferred embodiment of the invention includes, although the sensor 40 can take various forms and can be of many types known in the art, a series of filters for detecting the color of the developing material that comes from the developing material container 10 to the development material aggregate 20 is issued. The filter series considered in the present invention is shown in the diagram in 1 as a detection device 40 shown, which is attached so that it is the liquid developing material from the liquid developing material container 10 to the development material aggregate 20 is transported, can record. It will be appreciated by those skilled in the art that various multi-wavelength filter devices can be used to detect the color of the developing material, including devices that are in the liquid developing material container 10 are immersed, or devices that reduce light through the entire volume of the container 10 monitor.

The sensor 40 is with the controller 42 connected to the flow of the different colored, liquid refill developing materials belonging to the corresponding colors of a color matching system and which in from each of the feed containers 15A - 15Z to the feed tanks for liquid developing material 10 to be promoted from the donors 15A - 15Z to control. In a preferred embodiment, the controller 42 , as in 1 shown with the control valves 16A - 16Z connected to selectively activate them and thus the flow of the liquid developing material from each of the supply containers 15A - 15Z to control. It will be appreciated that these valves can be replaced with, or replaced by, pumping devices or any other flow control mechanism known in the art.

As noted earlier, the sensor includes 40 a number of filters according to the present invention. As such, the sensor includes 40 a suitable lamp, filter and photodetector, light from the lamp being directed through the filters and onto the development material. The reflection, transmission or emission of the developing material, while illuminated, is measured in turn using the light passing through each filter. In a well-designed approach, a predetermined number of relatively close filters with transmittance peaks distributed over the visible spectrum are used to determine a spectral distribution of a test piece, in this case the development material to be detected. By using a sufficient number of filters with degrees of transmission that are limited to sufficiently small wavelengths, the filter series can be used to provide a perceptible spectral strength distribution in order to identify the basic color components that make up the development material and thus determine its color.

The spectral distribution information can also be used to change the color of the development material, as to a particular color detection system, to determine such as the well-known standardized color grading system for the definition of uniform color spaces, which the Commission Internationale de I'Eclairage (CIE) was developed. The CIE color specification system provides so-called "three stimulus values" before colors specify and introduce device-independent color spaces. The CIE standards are widely accepted because using measured colors of relatively straightforward mathematical transformations directly are expressed in the coordinate systems recommended by the CIE can.

Once the color of the monitored development material has been determined, the color of the measured specimen, which, in addition to other measuring units, can also be in the form of a spectral distribution or a three-stimulus value, is given the known values corresponding to the desired output color (which can be supplied by the color matching system ) compared to determine the exact color formula that is necessary for the supply of operative development material, and thus to ensure correct color matching. This information is provided by the controller 42 processed to the valves 16A - 16Z to activate selectively, and thus the container 10 systematically deliver selected amounts of development material concentrate to the selected primary color components of the selected feed dispensers 15A - 15Z equivalent.

In a word is sensor 40 in the form of a series of filter elements in combination with a light source and a light detector in order to be able to carry out measurements which can be used to carry out a color mixing control. Measurements obtained from the filter series are compared with an a priori knowledge of similar optical properties of basic color components, from which the development material is made with the color selectable by the customer, in order to make an estimate of the Concentration levels of each of the color components in the container, as well as the corrections necessary to obtain the target concentrations that will result in the output color desired by the customer. The filter series thus provides a measurement of selected optical properties of the mixed development material in containers 10 ready, this information about the optical properties later to the controller 42 is supplied, which compares the measured information about the optical properties with corresponding known values of optical properties of the desired output color, which can be stored in a look-up table or a similar storage device. This information is used to determine the appropriate amounts of each of the color components that make up the container 10 about the activation of the valves 16A - 16Z should be added.

A method of performing the color mixing control process provided by the present invention is described below: initially, the light that shines through each filter is detected by a photodetector, thereby generating a set of N filter signals, the number of filter elements being the variable N are accordingly marked as f _n . Assuming there are 1 developer material compositions that correspond to a number of primary color components used to produce the developer material with the customer selectable color, the composition of each of the color components that make up the developer material passing through the filter and that with w _i can be calculated in the following way using the filter response f _n : {w i } = F ({f n })

One method of calculating this equation uses a previously determined matrix, A _ni : w i = Σ n A ni f n

The elements of A _ni refer in principle to the absorption spectrum of the development material components and to the transmission spectrum of the filter. However, the A _ni can be achieved by adjusting the most useful filter signals from a set of mixed developing materials. The accuracy of the w _i can be improved by using the knowledge of the question of which components are added to the mixed development material.

In a first method to which this invention can be applied, a set of filters is used which is equal to the whole number of primary or primary color components from which all of the customer selectable colors are mixed. The transmission of light through each of the components and filters is measured and the resulting matrix is inverted so as to obtain A _ni .

In a second method to which this invention can be applied, a set of filters is used which does not have to be equal to the whole number of primary colors from which all of the customer selectable colors are mixed. Filter responses from a large set of mixed toners are measured, and A _ni results from minimizing the RMS error between known and estimated concentrations w _ik for the i th component of the k th blend.

In a third method to which this invention can be applied, a set of filter responses and a set of known concentrations are used for a large set of mixed toners to train a neural network. The matrix multiplication defined above is replaced by the following calculation for the neural network: {w i } = NN ({f n }), the parentheses indicate that a set of filter functions are fed into the neural network and a set of weights are output.

In a fourth method to which this invention can be applied, a set of filters is used which does not have to be equal to the whole number of primary or primary color components from which all of the customer selectable colors are mixed. This method measures filter responses from a large set of mixed development materials. Different sets of A _ni result for different combinations of primary components. For example, a set of A _ni results for each unique combination of primary development materials, such as yellow and red; yellow and blue; blue and red; yellow, blue and red; etc. Again, every set of A _ni results from minimizing the RMS error between the known and expected concentrations w _ik for the i th component of the k th mixture of the set.

The operational behavior of some of the processes disclosed above has been tested by model methods. For example, by choosing six colors, namely the colors that are Pantone's yellow; warm red; Ruby red; Process Blue; and green, to our primary set of primary colors. It has been estimated that this set can reproduce approximately 75% of the Pantone colors that customers can choose. The transmissi On spectra of 70 mixtures of these primary colors were calculated, with each mixed development material having a total thickness of 1 wt% and 2-3 primary color components. The component concentrations differ from one mixture to the next by amounts as low as 0.01 wt%. Filter responses for idealized sets of Gaussian filters were also calculated, with each filter being specified by its center wavelength and full width at half the maximum transmission.

In a model example at Use of six 25 nm wide filters, whose centers at 425, 475, 525, 575, 625 and 675 nm, respectively, found that the direct method of calculating component concentrations only approximately works and possibly when measuring concentrations of some Base color components to non-zero values, but these base color components are not are necessarily present in the given mixture, or but overestimated Concentrations. These incorrect calculations can only be corrected with difficulty become the same, on the one hand, by all negatively estimated concentrations Be zeroed and secondly the knowledge of the Mixtures are used so as not to contain the estimated concentrations used components to zero, causing the RMS error in the estimated Concentrations can be corrected substantially. The RMS error in the individual components was approximately 0.36 wt%. By the Appropriate adjustment of filter positions and widths has been improved Set of filters determined as follows:

These new filters lead to an RMS error of 0.20 wt%. Of course, further optimization can be done reduce the RMS error even further. These estimates should, however, for a simple color control may be sufficient enough for some Applications are sufficient.

In another example, the first set of the six filters was used for the empirical adaptation of the A _ni , which led to a reduction in the RMS error to approximately 0.067 wt%. An empirical adjustment of the A _ni corresponding to the second filter set, carried out in the same way, reduced the RMS filter to 0.040 wt% and thus provided a more precise color control than the first method.

In another experiment, the test set of 70 mixtures was split into subsets, all of which were made from 2-3 primary development materials. Only the first set of filters was used for each set of blends and a set of A _{ni was} empirically optimized, with i only referring to the primary colors used in the set of blends. For 13 mixtures of yellow and warm red in the test set, the empirical optimization of the 2 × 6-A _ni matrix reduced the RMS error to 0.001 wt%. For 8 mixtures of yellow and ruby red in the test set, the empirical optimization of the 2 × 6-A _ni matrix reduced the RMS error to 0.001 wt%. For 6 mixtures of warm red and ruby red in the test set, the empirical optimization of the 2 × 6-A _ni matrix reduced the RMS error to less than 0.001 wt%. Since the test set contains only 3 mixtures of yellow, ruby red and process blue, the set was supplemented by three additional mixtures, which encompass a wider range of component compositions than the mixtures of the original test set. The resulting empirical optimization of the 3 × 6-A _ni matrix reduced the RMS error to 0.006 wt%. For seven mixtures of process blue and green in the test set, the empirical optimization of the 2 × 6-A _ni matrix also reduced the RMS error to 0.001 wt%. In all of these cases, it has been found that the accuracy of the component concentration estimates for the color control system is good enough to clearly distinguish all colors in the test set.

It is clear that the previous ones Procedures represent just a few of the many and different ways of working to control to provide a specified color output mixing color components using a series of filters could be implemented.

In summary, the present invention provides a system and method for color mixing control in an electrostatographic printing system. A developer container containing an operational solution containing developer material in a customer selectable color is continually refilled with the appropriate color, which in turn is controlled and monitored by selectively varying the rate of replenishment of various color components added to the supply container , A number of filter elements are used to measure the optical properties of the development material in the feed container so that the optical properties of the development material can be matched to the corresponding target optical properties. The present invention can be used to control and monitor the color of the developing material in the container by continuously monitoring and correcting the color of the developing material to a certain ratio of the color components in the container during extended periods resulting from very long print jobs to maintain. The present invention could also be used to mix a customer selectable color in situ, initially depositing and mixing approximate amounts of primary color components in the developer container, and this developer mixture blending fend is monitored and adjusted until the mixture has some predetermined optical properties.

Claims (6)

A system for providing a customer selectable color liquid developer material for printing a customer selectable color image area on an output tray in an electrostatic printing device, comprising: a plurality of developer material supply containers ( 15A . 15B . 15C , ... 15Z ) each containing a different colored liquid developing material concentrate corresponding to a basic color component of a color matching system; a development material reservoir ( 10 ) with which at least one of the plurality of development material supply containers ( 15A . 15B . 15C , ... 15Z ) is connected to provide an operational supply of liquid development material with the customer selectable color; a system for systematically dispensing a selected amount of liquid developing material concentrate from at least a selected one of the liquid developing material supply containers ( 15A . 15B . 15C , ... 15Z ) to the liquid development material storage container ( 10 ) to provide a selected primary color component to the operational supply of liquid development material; characterized by: a color detection measuring device ( 40 ) to monitor the color of the operational supply of liquid development material; and a control system ( 42 ) with the detection device ( 40 ) to selectively operate the systematic dispensing system in response to the measured color of the operational supply of development material, the control system ( 42 ) works in such a way that it provides the liquid development material with the color selectable by the customer by mixing the multitude of differently colored development material concentrates. The system of claim 1, wherein the sensing device ( 40 ) contains a filter series for measuring selected optical properties of the operational supply of liquid development material. A system as claimed in claim 1 or 2, wherein the customer selectable color is selected from a color guide showing a variety of different colors, and the color guide further provides a special mix of primary color components required to maintain the operational supply of liquid -To generate development material, and wherein the control system ( 42 ) is also set up so that it automatically mixes predetermined amounts of the basic color components in accordance with the special mixture provided by the color guide. System according to one of claims 1 or 2, wherein the control system ( 42 ) is set up to have optical properties of the supply of operational liquid development material from the detection device ( 40 ) with corresponding optical target properties that correspond to the color selectable by the customer. Electrostatographic printing device, at least a development subsystem for developing at least one section an electrostatic image with a liquid developing material one selectable by the customer Color contains to create an image area with a customer-selectable color on an output medium, wherein the subsystem corresponds to one of the preceding claims. An electrostatographic printing process in which at least a portion of an electrostatographic latent image is developed with a liquid developer material of a customer selectable color, comprising the steps of: providing a plurality of liquid developer material supply containers each corresponding to a different color liquid developer concentrate include a basic color component of a color matching system; optionally delivering at least one of the plurality of different colored developer concentrates to a liquid developer reservoir ( 10 ) to generate an operational supply of liquid development material with the color selectable by the customer; systematically dispensing a selected amount of liquid developing material concentrate of a selected basic color component to the liquid developing material storage container ( 10 ) to provide a selected primary color component to the operational supply of liquid development material; Monitoring a color of the operational supply of liquid development material; systematically dispensing a selected amount of liquid developing material concentrate chose the basic color component on the development material reservoir ( 10 ) in response to the color of the operational supply of liquid development material; and mixing the plurality of different colored liquid developer concentrates to provide the liquid developer with the customer selectable color.