DE102007037652A1 - Device and method for the metrological detection of a color of an object - Google Patents

Abstract

The The invention relates to a device and a method for metrological Capture the color of an object (12) in which using a Lighting arrangement (14), the at least two light sources (16 to 38) with different spectral light distributions, from the light sources (16 to 38) at the same time on light rays the object (12) are emitted. With the help of a sensor (40) becomes at least a part of the light rays reflected from the object (12) corresponding to at least one spectral sensitivity function detected. The spectral sensitivity function causes a spectral Filtering the light rays detected by the sensor (40).

Description

The The invention relates to a device and a method for metrological Capture the color of an object that has a lighting arrangement Light rays radiating to the object and at least one sensor a part of the light rays reflected by the object is detected.

From the document EP 1594015 A1 For example, there is known an optical density measurement for measuring the optical density of a toner image of an image forming apparatus, wherein a light source emits light onto a toner-colored portion of a substrate and a sensor detects the light rays reflected from the toner image.

From the document JP 2005-164261 A a control is known by which the intensity of the light emission of three light emitting diode chips is adjustable. The light emitting diode chips each emit light of different wavelengths. The light emitted by the light-emitting diode chips is detected by means of a single light monitoring sensor element.

From the documents US 6,621,576 B2 and US 6,384,918 B1 For example, arrangements for a spectrophotometer for non-contact color measurement of colored target areas, particularly printed test pages, are known. The spectrophotometer described has four sensor areas on which the light beams reflected by the target area to be detected impinge on the sensor area unfiltered, through a red filter, through a green filter and through a blue filter.

These color measuring arrangements have the disadvantage that they can only adequately describe the color sensation produced by a viewer with the aid of the RGB sensor. Such RGB sensors are used, for example, in scanners. A comparison of the spectral properties of scanner receivers of the colors red, green and blue with the normative fixed properties x, y and z, which are describing the normal-sighted people in 5 shown. Because of the difference in the spectral distributions, in particular because of the differences in the proportion of the overlap of the spectral curves, there is no possibility to simulate the eye characteristics with H RGB.

Out of the norm ISO 13655 Further color measuring arrangements are known which use a relatively complex measuring method in which a spectral decomposition and a further analysis of the light beams emitted or reflected by an object is carried out. To analyze the light beams, the spectrally dispersed light is detected by means of a sensor with sensor line, which usually has a 10 nm sensor resolution over the entire visible range. Such color measuring arrangements are sold for example by the company X-rite under the name SpectroEye and EyeOne. However, the metrological detection of the colors by means of such color measurement arrangements, in which the spectrally separated light is detected with spectral sensors, the disadvantage that they have a low detection sensitivity due to the spectral decomposition of the light and that color measuring arrangements are relatively complex and expensive with such sensors ,

Furthermore, the spectral composition of the light incident on the surface of the object is decisive for the color perception and the color impression of a viewer. To correctly capture the color perception of a viewer, the surface of the object must be illuminated with a suitable light spectrum. For this purpose, light sources are specified in standards, such as in the DIN 5033 ,

task the invention is to provide an apparatus and a method, a color measurement of the color of an object is simple and inexpensive especially feasible for a quick object change is.

These The object is achieved by that in the independent claims described invention solved. Advantageous developments The invention are defined in the dependent claims specified.

According to the invention for metrological detection of the color of an object, a lighting arrangement provided that at least two light sources with different having spectral light distributions, each simultaneously Emit light rays to the object. With at least one sensor becomes at least a part of the light rays reflected from the object corresponding to at least one spectral sensitivity function detected, wherein the spectral sensitivity function is a spectral Filtering the light rays detected by the sensor causes.

By the invention it is achieved that a cost-effective, stable, in particular long-term stable, reliable, efficient and rapid metrological detection of the color of an object is possible. As light sources can be used in front of some cost-effective light emitting diodes (light emitting diode diodes, abbreviated LED), which over a long period of their lifetime have a stable spectral distribution of their emitted light radiation, have a small design, have low heat losses and after switching on in a short time are ready, as they after switching on the desired amount of light in a short time.

By the simultaneous emission of the light rays through the at least two light sources is a rapid metrological detection of Color of an object possible, which also changes the color of surface sections Moving objects easy and reliable metrological can be detected. Furthermore, an on and off individual Light sources in the invention are not required to change the color one or more objects.

When Sensor is preferably a sensor used in which the spectral Sensitivity of the human eye is modeled. Preferably This sensor has three detection areas, each sensor area the light rays supplied to it by means of a spectral Sensitivity function detected. Through the spectral sensitivity function is a spectral filtering of the sensor or from the sensor area detected light radiation causes. This will change the color sensitivity of the human eye or the color perception of a human, in particular the normal spectral value function is modeled. There are but also sensors with more than three sensor areas can be used, if through these sensor areas measurement results with a spectral Sensitivity function can be determined, each areas correspond to at least one standard spectral value function or from which corresponding to the sensitivities of the normal spectral value functions Measurement results can be formed.

By a change in the intensity of at least one the light sources can be the spectral distribution of the lighting arrangement be changed, so that in a simple manner different lighting conditions can be simulated.

at a deviation of the spectral sensitivity function of the sensor or the spectral sensitivity functions of the sensor areas from the normal spectral value functions of the human eye by adjusting the spectral distribution of the illumination arrangement emitted light rays substantially the same measurement result be achieved, which would also result without the deviation. Alternatively, a measurement result can be generated, from which the Normal spectral value functions corresponding standard color values can be.

differences between the spectral sensitivities of the detector and the Standard spectral value functions for the human eye can be achieved by Adjustments to the spectral characteristics of the light sources bill be worn. Should z. B. reproduced the human color sensation in daylight and is the sensitivity of the detector in the red area too high, so a combination / setting of the light sources can be selected in the red area - compared to daylight - less Send out light.

The mutual influences of the spectral distribution of the light beams emitted by the illumination arrangement and the spectral sensitivity functions with which the sensor areas detect the light beams reflected by the object are mapped by the so-called Luther condition. The Luther condition is especially in the document Lang, Heinwig; Color reproduction in the media; ISBN 3-7881-4052-6-; Hansen-Schmidt Verlag; 1995; on page 131 , described.

Becomes adhering to the Luther condition, may appropriate the color sensation of a human color data are determined. In the invention it is by adjusting the spectral distribution of the Lighting arrangement emitted light beams easily possible a change of target illumination, a change of detection underlying normal spectral value functions (eg a change from the 2 ° normal spectral value functions to the 10 ° normal spectral value functions with a constant spectral detection sensitivity the sensor and vice versa) and / or a consideration the deviation of the color perception of a viewer from a normal viewer to effect. A mentioned deviation of the color sensation especially have viewers with a color vision disorder. Such color vision disorders are z. B. color defects, at the viewers are not allowed to use three chromates as usual Color perception has, but only two chromates. Thereby can such observers especially red and green objects not perceive as well as viewers with three chromates. By the invention Also, the color perception of people with a color vision deficiency simulates and the color of an object as a color sensation for a visually impaired observer can be detected metrologically.

With the aid of the invention, the detection of the color of the object can be carried out in a measuring process in which at least the area of the object to be scanned is illuminated simultaneously with the aid of the at least two light sources of the illumination arrangement. Furthermore, a part of the light beams reflected by the object can be detected in accordance with the at least one spectral sensitivity function. As a result, high measuring speeds are possible, by which the measuring arrangement can also be used in particular in a high-performance printing device or in a post-processing unit of a high Performance printing system for metrological detection of the color of a printed image during the printing process, ie inline, can be arranged.

For example can in a digital electrographic high-performance printing device the toner images or print images to be detected or measured printed carrier material with the aid of this measuring arrangement in the usual transport speed, z. At speeds of 2 m / s, sampled and the color of printed areas metrologically be determined.

The Application of the invention is not specific to the survey Color objects limited, especially not on printed images. It can be just as good at surveying other color objects such as B. displayed on screens images are applied. In printing, she is equally for both Pressure equipment or processes as well as for corresponding Copying devices or processes can be used, even if in This description does not always apply to both types is pointed out by devices or processes.

With Help during a printing process to generate printed color data or with help in a special calibration process of the printer device or Copier device determined color readings can be a color calibration of the respective device in particular printing parameters, for example electrographic parameters on electrographic printers or copiers can. Furthermore, a color control of the with the help of Printer or copier printed colors, in particular Image generation parameters are used as manipulated variables, for example, electrographic parameters in electrographic printers or copiers. The aim of such color control is to change the color perception of colors produced by the printer or copier at one Viewers to keep the same colors constant. Furthermore, with Help of metrologically captured colors a color management (color management), in particular the Color reproduction of the printer or copier with standard colors a suitable color conversion can be adjusted. With the help of Metrological detection of the colors can also be a color profile of the Printer or copier, which is then used as the basis for the color management can serve. Furthermore, with the aid of the invention the color of a printed and / or a printed substrate be easily captured, which then easy in the printer calibration and / or in color management as well as color calibration and color control can be used.

By The invention can in particular the stability of the color production both in the field of printing technology and in other fields the technology can be guaranteed. Alternative to the detection a fixed on the substrate toner image can the invention in the same way for detecting a by means of a Offset printing process generated image or one in one Inkjet printing process (ink-jet) generated printed image become. In particular, in electrographic printers or copiers also a non-fixed toner image, in particular a single color separation or the color of several printed color separations in an unfixed state on a picture carrier, like a photoconductor or an intermediate carrier, metrologically be recorded. It is advantageous, a transparent intermediate image carrier to use the color of the toner without any influence of the carrier material or with a negligible influence of the carrier material to be able to record metrologically.

One inventive method with the features of the independent method claim may be the same Be further developed manner as for the invention Device having the features of the independent device claim, in particular in the dependent claims.

To the a better understanding of the present invention is in With reference to the preferred embodiments illustrated in the drawings taken from specific terminology. It should be noted, however, that the scope of the invention should not be limited, since such Ver changes and further modifications to the devices shown and / or the described method and such other applications of the Invention, as they are shown therein, as usual current or future expertise of a competent Be considered professional. The figures show exemplary embodiments of the invention, namely:

1 a measuring system for measuring the color of an object;

2 a diagram with the spectral distribution of the illumination system of the measuring system according to 1 in a first embodiment of the invention, emitted visible light;

3 a diagram with the spectral distribution of the illumination system of the measuring system according to 1 in a second embodiment of the invention, emitted visible light;

4 a high-pressure electrographic printing system with a measuring system according to the invention and

5 the already mentioned comparison of the spectral properties of scanner RGB receivers with the normatively defined properties that describe the normal-sighted people.

In 1 is a measuring system 10 for measuring the color of an object 12 shown. In the present embodiment, the object 12 a printed image produced with the aid of a high-performance electrographic printing system, which is formed on a carrier material, preferably paper, as a toner image and coated on this carrier material in a suitable manner, e.g. B. has been fixed by heat, pressure, radiation and / or chemical treatment. The print or toner image preferably comprises a plurality of color separations, by which it contains in particular mixed colors. The color separations may include primary colors CMYK (cyan, magenta, yellow, black) and / or spot colors. Alternatively or in addition to the color measurement of the fixed toner image or of the finished printed image, the color of the unfixed toner image and / or individual color separations can be determined. The unfixed toner image or the color separations may be in a metrological recording of the color on an image carrier, on the intermediate image carrier or on a substrate, if necessary also in review in the arrangement and measurement of the color separations or the toner image on a transparent support or carrier material.

The measuring system 10 has a lighting arrangement 14 on, the several circularly arranged light sources 16 to 38 comprising, by their circular arrangement on the circular path shown by a dashed line the same distance from a to be illuminated detection area E and the at least part of the light generated by them radiate such that the light beams according to DIN ISO 13655 at an angle α = 45 ° to the surface of the object 12 incident. The main emission direction of the light rays of the light sources 16 to 38 is exactly 45 ° in the present exemplary embodiment, so that the light beams emitted in this main emission direction are at an angle of α = 45 ° to the surface of the object 12 to meet.

With the help of the measuring system 10 should be the color of the surface of the object 12 be detected metrologically. At least part of the light sources 16 to 38 generated on the surface of the object 12 in the detection area E incident light is from the surface of the object 12 reflects and hits the sensor surface of a sensor 40 , The sensor 40 is designed as a tristimulus sensor, wherein the three sensor regions have spectrally different sensitivities. Each sensor area is preceded by an optical filter. Each filter causes the sensor area associated with the filter to feed the object 12 spectral sensitivity function is detected. Taking into account a special spectral distribution of the light generated by the light source, the color sensation of the human being can be detected for a certain type of illumination. In doing so, they must illuminate the object 12 used light sources 16 to 38 the object 12 do not irradiate with light that produces this particular type of illumination. Rather, it is sufficient that from the light sources 16 to 38 emitted light together with the spectral sensitivity functions of the sensor areas lead to measurement results of the color measurement, which would be detected for the particular type of illumination when acquired with the nonspektralwertfunktionen. This can change the color sensation of a person while viewing the object 12 be simulated at this particular light source. With the help of the measuring system 10 Thus, the color perception of a human can be measured. The lighting arrangement 14 In particular, it can emit light whose spectral composition is the same as that used in the printing industry DIN 5033 , Part 7 standard daylight D50 (Daylight 5000 K - daylight with a color temperature of 5000 Kelvin) corresponds.

Each of the light sources 16 to 38 includes at least one light emitting diode (LED). Preferably, each light source comprises 16 to 38 a single LED or multiple LEDs of the same type, ie with the same spectral distribution of the light emitted by these LEDs. At least two light sources 16 to 38 emit light with a different spectral distribution. Preferably, two light sources forming a light source pair 16 / 22 . 18 / 24 . 20 / 26 . 28 / 34 . 30 / 36 . 32 / 38 the same spectral light distribution wherein the light source pairs have a different spectral distribution. Further, the intensity of each of the light sources 16 to 38 emitted light radiation regardless of the intensity of the other light sources 16 to 38 emitted light radiation can be adjusted, wherein the intensity can be changed in several stages or preferably continuously, wherein the intensity can also be adjusted so that at least one of the light sources 16 to 38 no light radiation is emitted to the detection area E, in which the area of the object 12 whose color is to be detected. By combining at least two light sources 16 to 38 with different spectral light distribution and the additional or alternative possibility of the intensity of the light sources 16 to 38 Adjusted light radiation can vary ne lighting types to illuminate the object 12 be generated and / or simulated, which in particular different standardized and non-standard Beleuchtungsar th, such as the aforementioned D50 but also light of artificial lighting, such as incandescent, gas discharge lamps, energy-saving lamps, dusk, fog, moonlight, etc., in a simple manner can be generated or simulated. Light-emitting diodes have the advantage that they are inexpensive, have a high stability of the spectral distribution and the intensity of the emitted light beams over their lifetime, have a small design, can be switched on quickly, are quickly ready for operation and very efficient. The intensity of the light sources 16 to 38 emitted light amount is also referred to as radiation flux.

For calibration of the measuring arrangement is for multiple light sources 16 to 38 one measurement signal for each of the sensor regions is determined one after the other and it is checked for each region and light source whether the received signal agrees with a stored reference signal. The measuring arrangement 10 Accordingly, at a preset drive signal of a light source 16 to 38 the brightness of this light source 16 to 38 with the help of the sensor 40 Determine separately for each sensor area and save the measurement result for later comparative measurements. This process can be repeated for each of the light sources so that the brightness is determined separately for each of the light sources.

In the later comparative measurements, the respective light source 16 to 38 driven with the same drive signal and determines the emitted light intensity. In case of a deviation of the brightness of the light source 16 to 38 becomes the drive signal of the light source 16 to 38 changed as long as the light source 16 to 38 again the same brightness. If a different spectral distribution or another measurement signal is present during the repeated comparison measurement, these occur at different light sources 16 to 38 in the same spectral ranges or over the entire spectral range of the illumination arrangement 14 on, it can be assumed that the spectral sensitivity function of at least one sensor range has changed compared to the original measurement. Such a change in the spectral sensitivity function is particularly in the event of a change in the optical properties of a filter preceding the sensor region or in the sensor 40 integrated filter possible. Such behavior of the filter is also referred to as drifting away of the filter. Thus, both from the individual light sources 16 to 38 provided light as well as the detection of the object 12 reflected light with the help of the sensor 40 be recalibrated and, if necessary, recalibrated. As an object 12 In this case, a white object is used in particular 12 which essentially covers the entire spectral range of the lighting arrangement 14 reflected. Alternatively, the light sources 16 to 38 and the sensor 40 be arranged to each other so that the light sources 16 to 38 emit light directly onto the sensor surface. Alternatively, objects can 12 be used with other colors for calibration, if this color is considered accordingly. By measuring the origin and the comparative measurements, the measuring system 10 Simply recalibrate, so the measuring system 10 after recalibration has the same detection characteristics as the measuring system 10 when capturing the original measurement results.

That from the light sources 16 to 38 radiated light can also with the help of between the light sources 16 to 38 and the object 12 arranged optical elements on the surface of the object 12 be directed. For this purpose, optical elements, such as optical waveguides, prisms and lenses are suitable, whereby the angle of incidence with which the light rays strike the surface of the object can be adjusted by these optical elements 12 incident. Further, by means of these optical elements, a bundling of the light sources 16 to 38 radiated light on the detection area E done. Furthermore, such optical elements can also be in the beam path between the surface of the object 12 and the sensor 40 be arranged around the surface of the object 12 Reflect reflected light rays suitable on the sensor surface, in particular to focus the reflected light rays and to focus on the sensor surface. In this case, a plurality of similar or different optical elements in the respective beam path can be arranged one after the other.

The circular arrangement of the light sources 16 to 38 the lighting arrangement 14 causes directional independence of the light sources 16 to 38 emitted light radiation can be avoided. Preferably, light sources which emit light having a similar spectral distribution are not arranged directly next to one another to provide directional dependencies in the reflection of the object being detected on the surface of the object to be detected 12 to avoid or at least reduce incident light rays. Preferably, light sources 16 to 38 radiating light having the same or a similar spectral distribution are arranged at circumferential points of the circular path of the circular array whose radii have an angle of 90 °. The light sources required to produce a desired illumination 16 to 38 are used to illuminate the object 12 switched on simultaneously, so that the color of the object through the sensor 40 be detected in a measuring process can. If several detection processes are to be carried out successively with the same type of light, the light sources can be used 16 to 38 the lighting arrangement 14 remain switched on unchanged, wherein the object, ie, for example, the test pattern or the test expression, can be changed or repeatedly detected. This is possible, for example, by several print images successively the detection range E of the measuring system 10 happen. Then, at appropriate times, the spectral distributions of the object 12 or from the objects to be detected reflected light rays using the sensor 40 recorded and further processed in a suitable manner.

The detection range of the sensor 40 is preferably parallel to the surface of the object 12 aligned and is thus perpendicular to the object 12 arranged. The sensor areas of the sensor 40 may be formed by three sectors of a single sensor element or by three different sensor elements. To determine an overall result, the measurement results output by the individual sensor areas can also be weighted differently. This is particularly advantageous if more than three sensor regions are provided for detection, each having different spectral sensitivity functions. Also by a different weighting of the sensor areas can with constant illumination of the object 12 Colors of the object 12 be determined metrologically with different lighting types.

Furthermore, at least one of the light sources 16 to 38 Radiate light rays in the non-visible area, especially in the ultraviolet range.

In 2 is the spectral distribution of the light sources 16 to 38 emitted light rays, wherein the light sources 16 to 38 in the exemplary embodiment 2 each radiate light of the same intensity, ie with the same radiation flux, each in a relatively narrow band range. The graph of the spectral distribution of the respective light source 16 to 38 emitted light quantity is in each case with the reference number of the respective light source 16 to 38 and the additional prefixed letter S. To simplify the designation of the light sources 16 to 38 emitted light beams is the wavelength of the maximum of the spectral distribution of the respective light source as the nominal wavelength of the respective light source 16 to 38 specified. The light sources 16 and 22 each give light with a wavelength of 412 nm, the light sources 18 and 24 each give light with a wavelength of 470 nm, the light sources 20 and 26 each give light with a wavelength of 529 nm, the light sources 28 and 34 each give light with a wavelength of 588 nm, the light sources 30 and 36 each give light with a wavelength of 647 nm and the light sources 32 and 38 each emit light at a wavelength of 694 nm. The course of the spectral distribution of the illumination arrangement 14 total emitted light is in 2 represented by the broken line indicated by S14. The spectral distribution of the lighting arrangement 14 is that of the light sources 16 to 38 generated total spectral distribution normalized to 100% so that a very uniform spectral distribution over the range between 400 nm and 700 nm of the illumination arrangement 14 in this first embodiment emitted light radiation results.

In 3 is a diagram with the spectral distribution of the illumination arrangement 14 of the measuring system 10 shown in a second embodiment of the invention emitted visible light. In 3 are the graphs of the spectral light distribution of the light sources 16 to 38 the lighting arrangement 14 emitted light radiation also designated S16 to S38. The light sources 16 to 38 each have a different spectral distribution of the emitted light than the light sources 16 to 38 according to the embodiment 2 , By the other spectral distribution of the light sources 16 to 38 in the embodiment according to 2 arises in the embodiment according to 3 also a different overall spectral distribution S14 of the illumination arrangement 14 emitted light. The different spectral curves S16 to S28 can be used to achieve almost any desired spectral overall course S14 of the illumination arrangement 14 emitted light rays by a targeted activation of individual light sources 16 to 38 or groups of light sources 16 to 38 adjust. This spectral profile S14 can be further changed by the intensity, ie the radiation flux, of the individual light sources 16 to 38 is further changed and set to a desired value. In the manner described, by a suitable selection and control of the light sources of the illumination arrangement 14 a desired overall spectral distribution S14 be generated, whereby almost any type of illumination for illuminating the object 12 can be set and selected.

Due to the relatively simple structure of the measuring system 10 and in particular when using light-emitting diodes as light sources 16 to 38 can the measuring system 10 be easily and inexpensively manufactured and has a small size. The measuring system 10 can also be arranged on a movable carriage, whereby a traversing measurement is possible. This is in the special possible if the carriage is orthogonal or oblique to a direction of movement of the object 12 is moved.

In the measuring system 10 For example, standard color values X, Y, Z are determined or calculated as measurement results with the aid of the sensor signals generated by the sensor regions. These are the light sources 16 to 38 and / or the spectral detection characteristics of the sensor regions of the sensor 40 adapted such that measurement results are determined according to the 2 ° standard spectral value function or the 10 ° standard spectral value function.

The measuring system 10 can be used particularly advantageous to a printer calibration of a printing or copying device with the help of the by the measuring system 10 to perform determined color measurements. A calibration can be carried out in electrographic printing or copying systems, in particular by adjusting the imaging parameters. Furthermore, with the aid of the determined color measurement values, a color control can be carried out during a printing or copying process, by means of which the color reproduction of predefined colors in consistent quality is ensured. This color control can be done with drifting color values, if necessary by a targeted change of Elektrografieparametern. Another possibility is to change the ink transfer properties of the printer by adjusting the data processing, in particular the tone curve. By changing the conversion of the color data (typically RGB data sets) in raster stages, changes in printing conditions can be compensated for or specifically varied.

Furthermore, the determined color values can be used for a color management, in particular to a color profile of an output device, eg. B. a printing device, copier or screen to make. Additionally or alternatively, with the aid of the sensor arrangement 10 Also, the color of an unprinted substrate, such as the paper color of paper to be printed, are determined to control the color reproduction in the printing process.

In 4 is a high performance electrographic printing system 100 represented, which is a measuring system according to the invention 10 having. That of a roll with the help of a unwinding device 106 unrolled web-shaped carrier material 110 is arranged with the help of two opposite, in 4 represented by circles, printing units of a printing unit 102 preferably with multicolor toner images on the front and / or back of the substrate 110 printed. The toner images are subsequently fused 104 on the carrier material 110 fixed, with a section of the fixed toner image using the measuring system 10 in conjunction with the 1 to 3 described, is detected before the carrier material 110 following a paper roll with the help of the rewinder 108 is wound up.

Alternative to the rewinder 108 It is also possible to provide other post-processing devices, such as cutting devices, converting devices, folding, stapling and binding devices, as well as other known post-processing units. The measuring system 10 may alternatively or additionally also at another location of the high-performance printing system 100 to be ordered. For example, the measuring system 10 in the processing sequence before the printing units of the printing unit 102 and the color of the substrate to be printed 110 determine. Arranging the measuring system 10 in front of the printing units for determining the color of the carrier material 110 is particularly useful when processing single sheets. When processing web-shaped carrier material 110 , as in the embodiment according to 4 , may be the color of the substrate 110 also at a position after the printing units of the printing unit 102 are detected when the printing units have not generated a printed image in the detected area. Furthermore, the measuring system 10 even before the fuser unit 104 be placed on the substrate 110 to capture generated toner images. Furthermore, alternatively or additionally, the color of the toner image on the surface of image carriers of the printing units can be detected. Alternatively or additionally, the color of fixed printed images can also be used in a further postprocessing unit (not shown) for postprocessing the fixed carrier material 110 to be ordered.

The invention can be used advantageously in conjunction with electrographic printing or copying machines whose recording methods for image formation are based in particular on the electrophotographic, magnetographic or ionographic recording principle. Further, the printing or copying apparatuses can use a recording method for image formation in which an image-recording element is directly or indirectly electrically driven pointwise. However, the invention is not limited to such electrographic printing or copying machines but can also be used in conventional printing processes such as offset printing processes, ink jet printing processes, screen printing processes, flexographic printing processes, gravure printing processes and other known printing processes. In particular, the color of control fields, of color marks, of control strips, of individual colors, of screened individual colors and of color separations printed on top of one another can be detected metrologically by the invention. As an alternative to certain color marks and control fields as well as to control strips, the color of at least a range of a printed image are detected by measurement. In particular, the color of a picture detail or logo contained in the printed image can be detected by measurement.

10

measuring system

12

object

14

lighting arrangement

16 to 38

light sources

40

sensor

e

detection range

α

angle of incidence

S14 to S38

graphs the spectral light distribution

100

High-performance printing system

102

printing unit

104

fuser

106

unrolling

108

rewinder

110

support material

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1594015 A1 [0002]
• JP 2005-164261 A [0003]
• - US 6621576 B2 [0004]
• - US 6384918 B1 [0004]

Cited non-patent literature

• - ISO 13655 [0006]
• - DIN 5033 [0007]
• - Long, Heinwig; Color reproduction in the media; ISBN 3-7881-4052-6-; Hansen-Schmidt Verlag; 1995; on page 131 [0017]
• - DIN ISO 13655 [0032]
• - DIN 5033 [0033]

Claims (21)

Device for metrological detection of the color of an object, having a lighting arrangement ( 14 ) containing at least two light sources ( 16 to 38 ) with different spectral light distributions, each of which at the same time light rays on the object ( 12 ), with at least one sensor ( 40 ), which is at least part of the object ( 12 ) reflected light beams corresponding to at least one spectral sensitivity function, wherein the spectral sensitivity function, a spectral filtering of the sensor ( 40 ) causes detected light rays. Device according to claim 1, characterized in that at least one sensor ( 40 ) upstream and / or into the sensor ( 40 ) integrated filter is provided, the or the spectral sensitivity function of the sensor ( 40 ) cause. Device according to one of the preceding claims, characterized in that at least three sensor areas are provided, which correspond to those of the object ( 12 ) in each case corresponding to a respective spectral sensitivity function, wherein the spectral sensitivity functions preferably each correspond to a standard spectral value function of the human eye or wherein starting from the with the aid of the device ( 10 ) determined measurement results under consideration of the spectral sensitivity function with which the measurement results have been determined, standard color values (X, Y, Z) can be determined according to the normal spectral value functions. Device according to one of the preceding claims, characterized in that the light sources ( 16 to 38 ) have such a different spectral distribution that the light beam mixture of the light sources ( 16 to 38 ), wherein the light distribution preferably corresponds to a daylight distribution or wherein from the light distribution, taking into account the actual spectral light distribution of the light beam mixture, a measurement result can be calculated with the aid of the sensor signal, which upon irradiation of the object ( 12 ) with a light beam mixture having a spectral light distribution of daylight from the sensor ( 40 ) would be issued. Device according to one of the preceding claims, characterized in that the intensity of at least one light source ( 16 to 38 ) is adjustable, so that the spectral light distribution of the light beam mixture of the at least two light sources ( 16 to 38 ) light beams is adjustable so that different types of illumination of the object ( 12 ) are adjustable. Device according to one of the preceding claims, characterized in that at least one light source ( 16 to 38 ) An optical filter is connected upstream. Apparatus according to claim 5 or 6, characterized in that a change in the intensity of at least one light source ( 16 to 38 ) and / or a change in the filter properties of the optical filter, a daylight distribution in a gray sky, a daylight distribution in direct sunlight, a light distribution of an incandescent lamp, a daylight distribution D50 and / or another standardized or non-standard daylight distribution and / or light distribution of another light source can be generated , wherein the intensity of at least one of the light sources ( 16 to 38 ) is reducible to zero, so that this light source ( 16 to 38 ) emits no light rays. Device according to one of the preceding claims, characterized in that the sensor ( 40 ) in a special detection mode of each of the light sources ( 16 to 38 ) radiated light radiation detected separately and that a memory is provided in which the measurement results determined in the detection mode can be stored separately. Device according to one of the preceding claims, characterized in that at least three light sources ( 16 to 38 ), preferably five, six or up to ten light sources ( 16 to 38 ) are arranged in a circular manner such that at least part of the light sources ( 16 to 38 ) radiated light rays on the object ( 12 ), so that the sensor ( 40 ) at least a part of the object ( 12 ) reflected light rays detected. Apparatus according to claim 9, characterized in that the circularly arranged light sources ( 16 to 38 ) radiate at least a portion of their light rays so that they are at an angle of 45 ° to the surface of the object ( 16 ), whereby the sensor ( 40 ) is arranged such that from the surface of the object ( 12 ) reflected light rays substantially perpendicular to the sensor surface meet. Device according to one of the preceding claims, characterized in that with the aid of the spectral sensitivity function, the color reproduction of an object detected by the human eye as color ( 12 ) is detected, wherein the sensor ( 40 ) as a measurement result preferably standard color values X, Y, Z outputs. Device according to one of the preceding claims, characterized in that the sensor ( 40 ) can be arranged in such a way that it blocks the light beams of the light sources incident on the object surface in a detection area ( 16 to 38 ) or that an object ( 12 ) in the reception area of the sensor ( 40 ) whose surface substantially covers the entire spectral range of the light source ( 16 to 38 ), whereby the intensity of the light emitted by the individual light sources ( 16 to 38 ) is adjusted so that the sensor ( 40 ) the desired light distribution of the illumination arrangement ( 14 ) detected. Device according to one of the preceding claims, characterized in that the light sources ( 16 to 38 ) are each formed by at least one light-emitting diode, wherein the intensity of the radiated light emitted by the light emitting radiation by means of a control unit is adjustable. Method for measuring the color of an object by measuring light rays on the object ( 12 ) emitted by means of a lighting arrangement ( 14 ), the illumination arrangement ( 14 ) at least two light sources ( 16 to 38 ) having different spectral light distributions, the light beams of the two light sources ( 16 to 38 ) at the same time light on the object ( 12 ) and in which at least part of the object ( 12 ) reflected light beams according to at least one spectral sensitivity function by means of a sensor ( 40 ), whereby the spectral sensitivity function spectral filtering that of the sensor ( 40 ) detected light rays is effected. The method of claim 14, wherein - at a first time with the sensor ( 40 ) in a special detection mode of each of the light sources ( 16 to 38 radiated light radiation is detected separately, the measurement results determined in the acquisition mode are stored separately, and a comparison measurement takes place at a second, later time in the acquisition mode, with a comparison of the measurement results of the comparison measurement with the measurement result of the original measurement. A method according to claim 15, wherein the determined measurement results determine the spectral distribution of each of the light sources ( 16 to 38 ) radiate emitted light radiation. The method of claim 15 or 16, wherein the determined measurement results the spectral distribution of the of each of the light sources ( 16 to 38 ) concern the intensity of the light radiation emitted by each of the light beams. Method according to one of claims 15 to 17, depending on the comparison result, an adjustment of the Intensity of at least one of the light sources and / or more Light sources for generating at least one type of illumination is set. Method according to one of claims 15 to 18, whereby in case of a negative comparison result an error message is issued. Method according to one of claims 15 to 19, wherein the detection mode is one of the normal operating mode of the device ( 10 ) for measuring the color of an object ( 12 ) is different mode. Method according to one of claims 15 to 20, wherein a device according to any one of claims 1 to 13 is used.