DE3134273A1 - Method for comparing the colours of surface regions having selected colours - Google Patents

Abstract

A colour television camera, a colour television monitor and an evaluation circuit are used to compare colours. The colour television camera, the colour television monitor and the evaluation circuit are connected to one another. The colour television camera is set to a selected colour. The setting is changed until the colour is displayed on the entire screen area. Values corresponding to the primary colour signals are then stored in the evaluation unit. Subsequently, the objects moving past the colour television camera are compared with the coloured surfaces in order to establish agreement with the stored values. <IMAGE>

Description

Method and apparatus for comparing the colors of

Surface areas with selected colors The invention relates refers to a method and an apparatus for comparing the colors of surface areas with selected colors.

Colored markings on objects are often monitored, to trigger control functions assigned to certain colors. For example bottles with different colors can be if they are delivered unsorted, are fed to a color checking device, i.e. emits the control signals with which Switches are operated to sort the bottles according to certain colors.

The invention is based on the object of comparing the colors of surface areas with selected colors, a method and an apparatus to develop that are economically in use. and a simple and fast one Enable setting.

The object is achieved according to the invention in that a color television camera is set to a surface that has a selected color until the surface with the selected color on the entire screen or at least approximately the entire screen of a color television monitor fed by the color television camera it is indicated that thereafter the selected color from the color television camera generated Primary color signals are stored and that subsequently after removing the surface with the selected color surfaces with the to be compared colors are brought in front of the color television camera, whose from the Color television cameras generated primary color signals with the stored primary color signals can be compared to determine whether they match.

Commercially available color television cameras already have adjustment devices for adapting the focal length to the distance between the camera and the object.

The. Alignment of the color television camera on the surface takes place through the viewfinder and the rotation of the objective lenses. For alignment up to Display of the selected area on the entire screen area takes little time needed. It can be the color of a surface, i. H. the interaction of Compare the color type and luminance with the colors of other surfaces. Through the Camera setting and the representation of the selected surface area on the TV screen, a minimum size of the colored area is specified. This minimum size ensures the reliable differentiation of colored surfaces from other colored surfaces or achromatic areas. The setting of the color television camera is easy to learn and does not require any physical knowledge. Therefore, the setting can also be carried out by trained personnel. After the short and easy setting the color television camera on the selected color and saving the corresponding The test of the colored areas can be started with reference signals. The above explained Process is particularly suitable for industrial use.

Preferably, the color television camera is on the surface with the selected color in focus. This allows small surface areas select for color comparison.

In an expedient embodiment, the color television camera blurred on the surface with the selected color. The one for the The surface section that is decisive for the color comparison becomes larger as a result. The comparison value corresponds to the mean value of the color on the selected surface section.

The surfaces with the colors to be compared are preferably used continuously passed the color television camera. The comparison can also be made during the movement of the colored surfaces take place.

Compared to the speed of the mechanically moved objects with the colored indicators, the line scan in the color television camera is very high high, so that no disturbing impairments occur.

An apparatus for performing the methods described above is that on that. color television monitor connected to the color television camera the amplified primary color signals are tapped and each to the inputs of window discriminators be placed in an evaluation circuit that the upper and lower limit values of the Window discriminators are adjustable that the window discriminators each have binary outputs and with the levels of the input signals above and below of the limit values indicating signaling elements are connected and that the outputs of the Window discriminators are conjunctively linked.

The storage of the reference primary color signals can be done with this Achieve arrangement by setting the limit values of the window discriminators. When the color television camera is set to the selected color, the Signaling elements indicate whether the primary color signals used as reference values are outside the limit values are. If the primary color signals are within the limit values, no further setting is required. Are the primary color signals outside the limit values, the corresponding actuating elements are used to activate the Limit values changed until the primary color signals, no longer outside lie. The setting of the actuating elements then corresponds to the reference primary color signals. It is also possible to provide an indication when the primary color signals are within the limit values are. The storage of the reference.

values then runs in a corresponding manner with the only difference from the fact that the display must be available when the adjustment is completed.

In an expedient embodiment it is provided that the primary color signals at the outputs of the cathodes of the television tube of the color television monitor Power amplifiers are fed to the window discriminators.

The primary color signals are at the outputs of the output stages of the color television monitor available for the basic colors red, green and blue. These amplified signals not only control the electron beam current of the color television picture tube, switch it also the window discriminators, their power consumption compared to that of the cathode control electrode circuits the picture tube, however, is only slightly. By connecting the window discriminators the quality of the display on the screen is therefore connected to the output stage outputs not affected.

A favorable embodiment is that between the outputs the output stages and the window discriminators AC-DC voltage converters are arranged. This arrangement enables the use of simply designed Window discriminators designed for analog input voltages.

The primary color signals are preferably each sent to several window discriminators, which are arranged in different modules, with three each, the three primary color signals of a color assigned window discriminators with the Outputs are conjunctively linked. With this arrangement, reference values for multiple colors can be saved.

If one of these colors is presented during the comparison, there is a control signal at the linked output of the assigned window discriminators to disposal.

The invention is illustrated below with reference to a drawing Embodiment explained in more detail, from which further features and advantages result.

FIG. 1 shows a block diagram of a device for comparison the colors of surface areas with selected colors.

FIG. 12 shows further details of the circuit arrangement shown in FIG.

A device for comparing the colors of surface areas with selected colors, a color television camera 1 includes a color television monitor 2, a camera adapter 3 and an evaluation device 4. With the color television camera 1 it is, for example, the TELEFUNKEN camera manufactured under the type FK 446. The color television camera 1 is with the camera adapter 3, the color television monitor 2 and the evaluation unit 4 connected. The camera adapter 3 is, for example, under the type FKA 40 device manufactured by TELEFUNKEN is used. At the color television monitor 2 is z. B. around the-manufactured by TELEFUNKEN under the type PALcolor 2000 TV.

The camera adapter 3 generates the vertical and horizontal deflection pulses, which are attached to the color television camera 1 and the monitor 2.

There are three channels 5, 6, 7 at the outputs of the color television camera 1 Primary color signals are available that correspond to the primary colors red, green and blue. The primary color signals reach the power amplifiers 8 in the color television monitor 2, 9, 14 are each connected to a cathode, not shown in detail, of a picture tube 11 which can be a shadow mask picture tube. The three electron beams of the picture tube 11 are thus through between the respective cathodes and the control electrodes applied voltages controlled. This type of control is also called R, G, B control known.

The outputs of the amplifiers 8, 9, 10 are each via channels 12, 13, 14 with inputs of AC-DC voltage converters 15; 16, 17 in the evaluation unit 4 connected. The AC / DC converters 15, 16, 17 several modules 18, 19, 20 which are identical to one another are connected downstream. In each Module 18, 19, 20 are the outputs of the AC / DC voltage converter 15, 16, ', 17 are each connected to an input of a window discriminator 21, 22, 23. The second inputs of the window discriminators 21, 22, 23 are connected to reference voltages applied, which are set by means of voltage divider circuits 24, 25, 26-. For the sake of clarity, the voltage divider circuits 24, 25, 25 are simplified shown. However, these are circuits with which the window discriminators 21, 22, 23 each an upper and lower limit can be set. the identically constructed window discriminators 21, 22, 23 each give at their outputs binary signals. The outputs are connected to inputs of an AND-Giieds 27, that the binary Linked signals. To every window discriminator 21, 22, 23 two indicator lights 28, 19 are connected. The indicator lights 28, z. B.

LED diodes respond when the input signal from the discriminator is below the set limit value. When the input signal of the discriminator is above the set limit value, the indicator light 29 responds.

The AND gate 27 feeds a further display element 30 and a time delay circuit 31, which is followed by an amplifier 32. With the amplifier 32 is the coil a relay 33 connected, which has a changeover contact.

The AC-DC converters 15, 16, 17, of which In Figure 2, the converter 15 is shown in more detail, each contain a low-pass filter 35 at the entrance. The low-pass filter 35 feeds the series connection of a diode 36 and a potentiometer 37, to the tap of which a capacitor 38 is connected.

With the capacitor 38 is a monolithically integrated window discriminator circuit 39 connected. The window discriminator circuit 39 has an input 40 for the upper limit value and an input 41 for the lower limit value of the window. Between a DC operating voltage and ground potential is the series connection of a resistor 42, a potentiometer 43 and a further resistor 44. Between the Resistor 42 and potentiometer 43, the voltage for input 40 is tapped.

The tap of the potentiometer 43 feeds the input 41.

The inputs 40, 41 are each with the non-inverting and inverting Input of a comparator, not shown, in the window discriminator circuit 39 connected. The inverting input of the first and the non-inverting input of the second comparator are connected to the capacitor 38. Any comparator a Schmitt trigger, not shown, is connected downstream. The outputs of this Schmitt triggers feed one output 45, 46 each via inverting amplifiers Window discriminator circuit 39.

Furthermore, the outputs of the Schmitt triggers are linked disjunctively applied to an output 47 of the window discriminator circuit 39.

The outputs 45, 46 are each designed as LED diodes Display elements 28, 29 connected via resistors 48, 49 to operating.

voltage are applied.

The color television camera 1 visually set on the surface 50 with the selected color. The setting includes the adaptation of the focal length of the color television camera 1 to the distance of the Camera from the surface 50. Another adjustment measure is through Alignment of the color television camera 1 on the surface for the extraction of To represent reference values desired range on the picture tube 11 that the entire area of the picture tube 11 indicates the area. The surface 50 is during evenly illuminated with this setting. Preferably contains the lighting only a small proportion of red light.

While maintaining the setting of the color television camera explained above 1 are then the reference values in the evaluation unit 4.

saved. The storage takes place via the voltage divider circuits 24, 25, 26, one of which is shown in more detail in FIG.

The indicator lights 28, 29 show in which level ranges the three primary color signals lie. Has that pending at the respective window discriminator Primary color signal is below or above the set limit value Level, then the associated indicator light 28 or 29 responds. The setting the voltage divider circuit 24, 25-, 26 is then activated by actuating the tap of the potentiometer 43 is changed until none of the indicator lights 28, 29 are any more speaks. For the respective primary color signal, this means that the corresponding Reference value is stored. These measures are used for all three primary color signals repeated..

After storing the reference values of the three primary color signals by means of the setting of the taps of the potentiometers 43 of the voltage divider circuits 24, 25, 26 give the window discriminators 21, 22, 23 binary at their outputs 47 Signals-the value "1". These signals are linked by the AND gate 27, that applies current to the indicator light 30.

From the response of the indicator light 30 it can be seen that the storage the reference values is complete.

The evaluation circuit 4 can then use further reference values be set by the modules 19, 20, whose structure corresponds to that of the module 18, can be used for storage.

After saving the reference values for the selected color the object with this color is removed from the color television camera 1.

Are then objects at the same distance and at the same Lighting conditions on the color television camera 1 moved past, then compares the evaluation unit 4 from the color television camera when scanning the respective Color generated primary color signals with the stored reference values. If they agree responds on the one hand to the indicator light 30 and on the other hand to the relay 33. Included the changeover contact 34 is actuated, which is used to control a not shown Soft can be used with items that have a certain color.

carry, be sorted out.

The color television camera 1 can be in focus or out of focus on the selected one Color of the surface 50 can be set. One focus selects a limited one Surface section from which it is z. B. to a colored spot for identification can act. The size of the selected surface section is based on the the rest also after the distance between color television camera 1 and surface 50.

By setting the color television camera 1 out of focus on the surface 50 can be a larger one even with a small distance between the camera and the surface Capture surface section. At the same time, an averaging of the detected zone achieved, d. H. the details of the colors at certain points of the Surfaces are no longer recorded precisely. This can be for certain use cases be useful if z. B. surfaces are to be compared that have a roughness exhibit.

The upper and lower limit values define the tolerance, within which a primary color signal is still detected as belonging to a reference value.

The tolerance can be set very small, so that too Color shades of a color can be reliably distinguished.

Quality monitoring is a useful field of application of the method of colored plastic objects that are exposed to certain mechanical loads are. Such plastic objects are e.g. B. Boxes for holding bottles. Due to aging processes and frequent mechanical stresses, the strength drops according to the boxes. This makes itself inter alia. a change in color on the surface of the boxes noticeable. By comparing the colors with that of flawless boxes existing paint, the boxes with reduced strength can be placed in unloading stations, Record filling stations etc. immediately and sort them out.

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Claims (11)

Claims W Method for comparing the colors of surface areas with selected colors, characterized in that a color television camera (1) is set on a surface (50) having a selected color until the surface (50) with the selected color on the entire screen (all) or at least approximately over the entire screen (11) one from the color television camera powered color television monitor (2) is displayed that then the from the color television camera (1) Primary color signals generated for the selected color are stored and that then after the removal of the surface (50) with the selected color Brought surfaces with colors to be compared in front of the color television camera (1) are, whose primary color signals generated by the color television camera (1) with the stored primary color signals compared to determine the agreement will. 2. The method according to claim 1, characterized in that the color television camera is focused on the surface (50) with the selected color. 3. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the color television camera (1) on the surface (50) with the selected Color is out of focus. 4. The method according to claim 1 or one of the following claims, characterized characterized in that the surfaces with the colors to be compared are continuous be moved past the color television camera. 5. Apparatus for performing the method according to claim 1 or one of the following claims, characterized in that the one with the color television camera (1) connected color television monitor (2) tapped the amplified primary color signals and each to the input of Fensierdiskriminatoren (21, 22-, 23, 39) in an evaluation circuit (4) Be placed that the upper and lower limits of the window discriminators (21, 22, 23, 39) can be set so that the window discriminators (21, 22, -23, 39) each have binary outputs 47) and with the level of the input signals above and signaling elements (29, 28) indicating the limit values are connected and that the outputs (47) of the window discriminators (21, 22, 23, 39) are conjunctive are linked. 6. Apparatus according to claim 5, characterized in that the primary color signals at the outputs of the cathodes of the television tube of the color television monitor (2) feed Final amplifiers (8, 9, 10) are fed to the window discriminators (21, 22, 23, 39). 7. The device according to claim 5 or 6, d a d u r c h g e k e h n z e i c h n e t that between the outputs of the output stages (8, 9, 10) and the window discriminators (21, 22, 23, 39) AC-DC voltage converters (15, 16, 17) are arranged. 8. Apparatus according to claim 7, characterized in that the primary color signals each to several window discriminators (21, 22, 23, 39), which are in different Modules (18, 19, 20) are arranged, are applied, each three, the three Window discriminators assigned to primary color signals of a color with the outputs (47) are conjunctively linked. 9. Apparatus according to claim 8 or 9, characterized in that the AC / DC voltage converters (15, 16, 17) each have at least one Low-pass filter (35) and a rectifier circuit (36) with a downstream smoothing element (37, 38) included. 10. Device according to claim 5 or one of the following claims, characterized in that the input (40) for the upper limit value and the input (39) for the lower limit value of the respective window discriminator (39) to a Voltage divider circuit consisting of three resistors (42, 43, 44) is connected by which the middle one is a potentiometer (43) whose tap is connected to the input (41) for the lower limit value is connected, while the input (40) for the upper Limit value placed at the junction of the first two resistors (42, 43) is. 11. The device according to claim 5 or one of the following claims, d u r c h e k e n n n z e i c h n e t that the conjunctively linked outputs (47) of the window discriminators (21, 22, 23, 39) with an indicator light (30) and a relay (33) are connected.