WO2021110671A1

WO2021110671A1 - System for the measurement of items to be measured

Info

Publication number: WO2021110671A1
Application number: PCT/EP2020/084106
Authority: WO
Inventors: Reto HÄRING; Nina Mauser
Original assignee: Instrument Systems Optische Messtechnik Gmbh
Priority date: 2019-12-02
Filing date: 2020-12-01
Publication date: 2021-06-10
Also published as: DE102019132712A1

Abstract

The invention relates to a system for the colorimetric and/or photometric measurement of light reflected by the surface of an item to be measured (2, 2.1), having an imaging colorimeter (1), in the field of view of which the item to be measured (2, 2.1) is located, wherein the colorimeter (1) projects onto a first partial section of the image area formed by the image sensor in the colorimeter (1) a first view of the item to be measured (2, 2.1) from a first perspective. The problem addressed by the invention is that of making possible simultaneous measurements from different perspectives and measurements of three-dimensionally shaped surfaces of items to be measured, without requiring a plurality of colorimeters for this or having to carry out a plurality of measurements one after the other. To this end, the invention proposes that one or more deflecting optical systems (3, 4, 5) arranged in the field of view of the colorimeter (1) project at least one second view of the item to be measured (2, 2.1) from a second perspective onto at least one second partial section of the image area. The invention further relates to a method for the colorimetric and/or photometric measurement of an item to be measured (2, 2.1) using a system of this kind.

Description

System for the measurement of measurement objects The invention relates to a system for the colorimetric and / or photometric measurement of light emitted from the surface of a measurement object, with an imaging colorimeter, in the field of view of which the measurement object is located, the colorimeter on a first section of the light emitted by the image sensor The image area formed by the colorimeter depicts a first view of the measurement object from a first perspective. The invention also relates to a method for colorimetric and / or photometric measurement of a measurement object.

Such systems are known and are generally used to check the quality of different measurement objects, in particular TV, smartphone and tablet displays. The colorimeter is typically directed vertically onto the display surface, so that the sensor surface of the image sensor of the colorimeter lies in a plane parallel to the display surface. This arrangement ensures high precision and short measuring times when measuring two-dimensional displays. However, such a system also has disadvantages and limitations. On the one hand, curved or arched displays are being used more and more often nowadays on the side edges or on the whole. However, the curved surfaces cannot be detected or only insufficiently detected by the two-dimensional imaging colorimeter because the direction of radiation in the corresponding surface areas of the display deviates greatly from the viewing direction of the colorimeter. Second, it is with a single colorimeter It is not possible to carry out measurements from different perspectives at the same time, but this may be necessary when checking the quality of displays when it comes to determining, for example, the dependency of color and photometric parameters on the angle of radiation, i.e. on the viewing direction on the display .

Both of these disadvantages could be eliminated, for example, by using several colorimeters that simultaneously measure a measurement object. However, such a solution would be associated with higher costs and therefore uneconomical. Another possibility of eliminating the disadvantages described is to carry out several measurement steps one after the other. Between the individual measuring steps, the colorimeter and the measuring object are moved relative to one another in order to e.g. detect the areas of the curved side edges of a display or to simulate different viewing angles. This approach is complex, time-consuming and therefore also uneconomical.

So far, the disadvantages described have often been accepted in the quality control of displays. For reasons of economy, the curved display edges are not checked, with corresponding negative effects on the product quality.

It is therefore the object of the invention to further develop a system of the type mentioned at the outset in such a way that simultaneous measurements from different perspectives and measurements of three-dimensionally shaped measurement object surfaces are possible without the need for multiple colorimeters or multiple measurement steps in succession.

To solve this problem, based on a system of the type mentioned at the beginning, the invention proposes that one or more deflection optics arranged in the field of view of the colorimeter image at least one second view of the measurement object from a second perspective on at least a second section of the image area. In the context of the invention, a view of the measurement object is to be understood as a complete view or only a partial view, ie a view showing only a section of the measurement object.

When arranging the respective deflecting optics, the shape of the measurement object and, in particular, any three-dimensional characteristics can be taken into account. Those surface areas of the measurement object which cannot or can only insufficiently be detected directly by the colorimeter are imaged on the second partial section of the image area via the deflecting optics. Furthermore, it is possible to use the deflecting optics in the second partial section to generate different perspectives, i.e. views from different viewing directions in the plane of the image surface.

With the system according to the invention, it is thus possible to measure objects with two- or three-dimensional surface structures from different perspectives with just one colorimeter in just one measurement step.

The system according to the invention is particularly advantageous when the measurement object is a display, in particular a TV, smartphone or tablet display. As in conventional systems, the display is expediently arranged in such a way that the display surface lies parallel to the plane of the image sensor of the colorimeter. By suitably arranging one or more deflection optics, different perspectives with regard to the distance and / or the viewing angle on the display can now be checked by the colorimeter in just one measurement.

In a particular embodiment of the invention, the display has a curvature at least on one side edge, with deflection optics assigned to the respective side edge, that is to say adapted to the curvature, being provided. The adaptation is therefore carried out for a specific display geometry and is therefore suitable for being optimally used in quality assurance for mass products for the corresponding display type. The number and characteristics of the deflecting optics, ie the degree of Adaptation to the geometry of the measuring object depends on the requirements for the quality of the measurement.

A preferred embodiment of the invention provides that the deflecting optics are at least partially designed as reflective optics, in particular as a (e.g. right-angled) deflecting prism. Reflective optics can serve particularly easily as deflecting optics and can also be combined with one another. Mirrors and standardized deflecting prisms are particularly economical due to their simple geometry. The fine adjustment and correction can be carried out by positioning the reflective optics relative to the measurement object. Special prisms can also be used.

An alternative or additional development of the invention provides that the deflecting optics are implemented at least partially by means of fiber optics. This flexible solution enables viewing from many perspectives. For example, it can be achieved that with a curved surface the perspectives are always oriented perpendicular to the surface.

An expedient development of the invention provides that the deflecting optics can be fixed, displaced and / or rotated on the supporting frame. Due to the flexible arrangement, the deflection optics can be adjusted to the measurement requirement. For example, the optics can be adjusted so that the display is in the focal plane of the colorimeter in all perspectives at the same time. As a further example, the viewing angle of the other perspectives can be adjusted to the measurement requirements (e.g. to a defined 30 °).

A particularly preferred embodiment of the invention provides that the colorimeter has a spectroradiometer. The exact data of the spectrometer measurement can be used as a reference in order to determine color and / or photometric quantities from the recorded image data (eg RGB image data). A suitable colorimeter with a spectrometer is described, for example, in EP 3054273 A1. In the method according to the invention, image data are first recorded by means of the colorimeter using the system described above. The image data are then processed, with the image data of the first and second partial sections of the image area being assigned to the associated surface areas, i.e. those surface areas of the measurement object that are imaged in the respective partial sections of the image area, using the known imaging properties of the deflecting optics. The processor can be used to calculate color and / or photometric quantities for a plurality of positions on the surface of the measurement object from the image data. The determined sizes are automatically assigned to the corresponding positions on the surface from where the light emission occurred during the image acquisition. In this way, for example, display errors found in the context of quality assurance can be determined, precisely localized and interpreted. An advantageous embodiment of the invention provides that the deflecting optics are arranged in such a way that there is a direct line of sight between the colorimeter and a part of the surface of the measurement object, and the colorimeter on the first part of the image area shows the first view of the part of the measurement object from the first perspective images, and the deflecting optics images the same partial area on the second partial section of the image area from the second perspective. This makes it possible to measure the same part of the surface from several perspectives at the same time. By comparing the measurements from different perspectives of one and the same sub-area, a correction rule for taking into account the dependence of the colors in the RGB or XYZ color space on the viewing angle can be derived.

In the following, exemplary embodiments of the invention are explained in more detail with reference to drawings. Show it:

FIG. 1: a schematic view of a system according to the invention in a first embodiment; FIG. 2: a system according to the invention in a second embodiment;

FIG. 3: a system according to the invention in a third embodiment;

FIG. 4: a system according to the invention in a fourth embodiment;

FIG. 5: a system according to the invention in a fifth embodiment;

FIG. 6: a system according to the invention in a sixth embodiment;

FIG. 7: a system according to the invention in a seventh embodiment;

FIG. 8: a system according to the invention in an eighth embodiment. In the first exemplary embodiment shown in FIG. 1, an imaging colorimeter is denoted by the reference number 1. The colorimeter 1 has an image sensor and integrated optics (not shown). A processor for data processing is integrated in the colorimeter 1. In other embodiments according to the invention, however, the processor can also be arranged outside the colorimeter 1 and communicate with the colorimeter 1 via a data interface. The colorimeter 1 is aimed at a measurement object 2 located in its field of view. The integrated optics (objective) of the colorimeter 1 forms a first view of the measurement object 2, corresponding to the first perspective shown, which results from the relative arrangement and alignment of the colorimeter 1 and measurement object 2, on a first section of the image sensor of the colorimeter 1 formed image area. The plane of the image sensor is aligned as parallel as possible to the object surface 2a to be measured. Furthermore, deflection optics, in this exemplary embodiment a prism 3, are shown. The deflecting optics are located in the field of view of the colorimeter 1, so that, together with the integrated optics, a second view of the measurement object 2 from a second perspective, which results from the relative arrangement and alignment of prism 3 and measurement object 2, onto a second Depicts part of the image area of the image sensor.

The different perspectives are indicated by the directional arrows in FIG. As described above, the object surface 2a is measured directly by the colorimeter 1. The measurement result obtained by direct measurement (colorimeter 1 - object surface 2a) is used for the color and photometric assessment of the light emission from the object surface 2a in the first perspective directed perpendicularly to the object surface 2a.

In order to also be able to measure the optical properties of the object surface 2a or parts thereof from perspectives at different angles and / or distances, the prism 3 is provided in the system according to the invention. The beam path is deflected onto the image sensor of the colorimeter 1 by the prism 3 functioning as deflecting optics. This makes it possible to assess the color and photometric properties of the object surface 2a from the other perspective. By positioning and dimensioning the deflecting optics, the most varied of distances and angles of inclination can be implemented here. A particular advantage of the system according to the invention is therefore that the light measurements on the measurement object 2 can be carried out simultaneously from several perspectives in just a single measurement process.

Systems according to the invention are used in particular for checking the light emission properties of the display of a TV device, smartphone or tablet for the purpose of quality assurance. In newer smartphone and tablet models, the displays are increasingly being designed with curved or beveled edges. In the second exemplary embodiment shown in FIG. 2, the measurement object 2 is such a smartphone 2.1 with a display that is curved at the edge, so that light emission also takes place from the display edge to the side. The object surface 2a to be measured, i.e. the display curved over the edge, In contrast to the first exemplary embodiment in FIG. 1, it has a three-dimensional expression here. In order to be able to measure the optical properties of the object surface 2a also at the curved side edges, the prism 3 is arranged laterally next to the smartphone 2.1. As a result of this positioning of the prism 3, as indicated by the directional arrows, the curved side edge of the display can also be measured. The total internal reflection of the prism 3 is used as a mirror to see the curved side edge. The optical density of the prism 3 makes it possible to achieve the same focus properties on the upper, flat area and the lateral, curved area of the object surface 2a. A fine adjustment of the focus can be achieved by moving the prism 3 relative to the object surface 2a.

By arranging a further deflection optics on the opposite side of the smartphone 2.1, the curved side edge could also be measured here. When processing the measurement data, images from the edge area of the curvature, which are captured both directly and via the deflecting optics by the colorimeter 1, can be used to finally summarize and display the measurement result in a single two-dimensional image. The third exemplary embodiment shown in FIG. 3 essentially corresponds to the exemplary embodiment from FIG. 2. A mirror 4 is used here instead of a prism 3 as the deflecting optics.

A fourth exemplary embodiment is shown in FIG. 4, in which two mirrors 4 are used as deflecting optics. The beam path is correspondingly deflected from the object surface 2a at the two mirrors 4 in each case. This refinement has the advantage that the image of the object surface 2a at the lateral edge on the image sensor of the colorimeter 1 takes place in the correct direction.

FIG. 5 shows a fifth exemplary embodiment in which a fiber optic 5 is used as the deflecting optic. The fiber optics 5 can be arranged on the image side in such a way that each fiber end is directed perpendicularly onto the (free-form) surface of the display 2.1. On the camera side, the fiber optics 5 can be perpendicular to the Colorimeters are aimed, for example, in the form of a tightly packed bundle of fibers. In this way, a measurement geometry can be achieved that measures the properties of every point on the display when viewed vertically (indicated by the double arrow). FIG. 6 shows a sixth exemplary embodiment in which a total of four prisms 3 are arranged around the three-dimensional measurement object, in this case a cube 2.2. With the help of the four prisms 3, five of the six sides of the cube 2.2 can be measured when viewed through the colorimeter 1. Using a processor (not shown), the image data of the individual sections of the cube are assigned to the associated surface areas of the cube 2.2 based on the known imaging properties of the prisms 3 and summarized in a two-dimensional image display, as shown schematically in the box at the top right in FIG. The measurement data of a spectroradiometer can also be used here in order to correct the image data of the colorimeter 1 colorimetrically and photometrically. The spectroradiometer is integrated in the colorimeter.

In FIG. 7, two deflection optics which are arranged on a supporting frame 6 are shown. As indicated by the arrow symbols, the frame 6 including deflection optics can be displaced along the three spatial axes and is also rotatably mounted so that the deflection optics can be arranged relative to the measurement object 2 with the greatest flexibility depending on the requirements. For example, it is also possible to carry out several measurements in quick succession from different perspectives.

The exemplary embodiment shown in FIG. 8 essentially corresponds to the exemplary embodiment from FIG. 1. The colorimeter 1 detects the surface 2a of the measurement object 2, the central areas of the measurement object 2 being mapped orthogonally according to the optical path 7a on the image sensor 8 in the colorimeter. An edge area, here the sub-area 9 of the measurement object 2, is imaged at an angle according to the optical path 7b. An image 8a of the measurement object 2 is created on the image sensor 8. The deflecting optics 3 is oriented and positioned above the measurement object 2 in such a way that the sub-area 9 of the surface 2a of the measurement object 2 is also at a right angle is measured according to the optical path 7c. An image 8b is produced on the image sensor 8. With this structure, the same partial area 9 of the surface 2a of the measurement object 2 can be imaged at different viewing angles. This is of particular interest in the case of measurement objects 2 in which the spectrum of the emitted light is dependent on the emission angle or viewing angle, that is to say, for example, LED wafers or OLED displays.

A correction of the angle dependency of the colors in the RGB or XYZ color space can be derived from the comparison of the RGB data from the images with and without deflection optics (8b and 8a) in the areas corresponding to one another.

List of reference symbols:

1 colorimeter

2 object to be measured 2a object surface to be measured

2.1 Display

2.2 dice

3 prism

4 mirrors 5 fiber optics

6 frame 7a optical path 7b optical path 7c optical path 8 image sensor

8a illustration without deflection optics 8b Illustration with deflecting optics

Claims

1. System for the colorimetric and / or photometric measurement of the light emitted from the surface (2a) of a measurement object (2, 2.1), with an imaging colorimeter (1) in whose field of view the measurement object (2, 2.1) is located, the colorimeter (1) depicts a first view of the measurement object (2, 2.1) from a first perspective on a first section of the image area formed by the image sensor of the colorimeter (1), characterized in that one or more deflection optics (1) arranged in the field of view of the colorimeter (1) 3, 4, 5) depict at least one second view of the measurement object (2, 2.1) from a second perspective on at least a second partial section of the image area.

2. System according to claim 1, characterized in that the measurement object (2, 2.1) is a matrix display, in particular a TV, smartphone or

Tablet display.

3. System according to claim 2, characterized in that the matrix display has a curvature at least on one side edge, wherein one of the respective curvature associated deflection optics (3, 4, 5) is provided.

4. System according to one of the preceding claims, characterized in that the deflecting optics (3, 4, 5) is at least partially designed as reflective optics, in particular as a deflecting prism.

5. System according to one of the preceding claims, characterized in that the deflecting optics (3, 4, 5) is at least partially designed as fiber optics (5).

6. System according to one of the preceding claims, characterized in that the deflecting optics (3, 4, 5) is arranged on a supporting frame (6).

7. System according to one of the preceding claims, characterized in that the colorimeter (1) includes a spectroradiometer.

8. System according to one of the preceding claims, characterized in that the deflecting optics (3, 4, 5) is arranged such that between the colorimeter (1) and a portion (9) of the surface (2a) of the measurement object (2, 2.1 ) there is a direct line of sight, the colorimeter (1) depicts the first view of the sub-area (9) of the measurement object (2, 2.1) from the first perspective on the first section of the image area, and the deflection optics (3) the same sub-area on the second sub-section depicts the image surface from the second perspective.

9. Method for the colorimetric and / or photometric measurement of a

Measurement object (2, 2.1) using a system according to one of the preceding claims, with the method steps:

- Recording of image data by means of the colorimeter (1),

- Processing of the image data, with the image data of the first and second partial sections of the image area using the known imaging properties of the deflecting optics (3, 4, 5) by means of a processor associated surface areas of the measurement object (2, 2.1) are assigned.

10. The method according to claim 9, characterized in that color and / or photometric variables for a plurality of positions on the surface of the measurement object (2, 2.1) are calculated from the image data by means of the processor.

11. The method according to claim 9 or 10, characterized in that the image data of the colorimeter (1) are corrected colorimetrically and photometrically by means of the measurement data of the spectroradiometer.

12. The method according to any one of claims 8-11 using a system according to claim 8, characterized in that a correction of the angular dependence of the colors of the emitted light of the measurement object (2 , 2.1) is derived in the RGB and / or XYZ color space.