Colour sensor arrangement for reading colour marks

p0001The invention relates to a color sensor arrangement for reading colored marks such color arrays are according to the preamble of claim 1. Particularly preferably used to read color print brands in a short working distance. The color sensor system is also suitable for many other applications. Reference is here on the job control or monitoring of donation procedures (lacquer), Banderolen-, label or mark detection and monitoring of coating processes. In question, the application is also used for checking the presence of objects. Generally, two versions with 10 mm or 60 mm sensing distance are provided.

p0002The object of the invention is to develop such a color sensor array so that they are compatible with existing contrast scanners short scanning distance and the housing dimensions of a contrast scanner to be maintained as far as possible, ie, that the greater number of optical and optoelectronic components in a color sensor arrangement in the smallest possible space is housed, but the high demands on the precision of arrangement of the optical and optoelectronic components fully met.

p0003To achieve this object the features of the characterizing part of claim 1 are provided.

p0004According to the invention is therefore carried out with a auto-collimation, whereby to reduce the optical crosstalk a geometric beam splitter is used. In this way optical cross-talk is reduced by contamination of the outwardly facing surface of the objective lens within the illumination cone as a result of shadowing occurring preferably centrally.

p0005the lens is anti-reflective coating on both sides over the entire spectral bandwidth of the semiconductor radiation sources used for the reduction of optical crosstalk more preferably.

p0006The selective use of high-performance LEDs with small beam angle as a semiconductor radiation sources has the result that the transmission opening can be formed in comparison to the receiving opening significantly smaller. In this respect, the beam splitter used in the invention also offers significant advantages in the current account.

p0007The geometric beam splitter is advantageously constructed in accordance with claim 2, wherein the mirror surface can be arranged according to claims 3 or 4th

p0008In the embodiment of claim 3, only one central area of ​​the disk is provided with a mirror coating which is hit by the narrow emitted light beam of the semiconductor radiation sources.

p0009In the embodiment of claim 4, the transmitted light beam of the semiconductor radiation sources go through the plate while the reception light is reflected by the mirror coating on the receiving device.

p0010A structurally particularly compact arrangement is achieved by the measures according to claims 5 and 6. FIG. In this way, the advantages of the use of dichroic mirrors are achieved in structural compactness.

p0011Particularly advantageous is an embodiment with three semiconductor radiation sources in the three primary colors, which are advantageously arranged according to claim 7, in order to achieve on the one hand a compact housing and on the other hand equal optical paths for the radiation of the various semiconductor radiation sources. Here is advantageously proceeded claim 8.

p0012The measure of claim 9 is a concentration of the transmitted light is advantageously obtained at the beam splitter, which benefits one hand an exact geometric radiation separation that is also a favorable energy balance.

p0013In order to achieve a sharp edge pixel on the markings provided with the objects, the aperture is provided according to claim 10 according to the invention expediently.

p0014Of particular advantage is the embodiment defined in claim 11 and 12, because in this way all the key components are combined into a single compact assembly in a precise manner.

p0015For installation, the training according to claims 13 or 14 is advantageous because dannn the individual components are inserted prior to the application of the lid from the open side into suitably arranged grooves in the barrel produced as precision injection molding with Connector and arranged so precise , in order to be subsequently fixed by application of the lid in this precision arrangement of the individual components. By the application of the cover creates a geschlossesner box containing only five lateral openings for the three LED's, the receiver and the lens.

p0016In particular, for mounting the rectangular shape of most optical and optoelectronic components is expedient according to claim 15th Circular lenses can in this by training according to claim 16 are included s system.

p0017The compact design of the color sensor assembly according to the invention is further promoted by the formation of claim 17th The invention thus provides the liberated by the relative to the received light beam emitted light beam narrower space for accommodating the PCB is used.

p0018The invention is described in the following example with reference to the drawing; This shows:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic partially sectioned and partially block-diagram representation of a color sensor arrangement of the invention,</dd><dt>FIG. 2</dt><dd>an enlarged sectional view of the optical portion of the color sensor arrangement of the invention,</dd><dt>Fig. 3</dt><dd>is a schematic front view of the object of Fig. 2 in the direction of arrow III without the lens and</dd><dt>Fig. 4</dt><dd>the top view of a circular lens with rectangular lugs.</dd></dl>

p0019In all figures, like reference numerals designate corresponding components.

p0020Referring to FIGS. 1 to 3, the core of the color sensor arrangement of the invention is a tube 36 with a lower retainer lug 37, which are arranged in a rectangular box-shaped housing 21 made of metal, which can be opened in an appropriate manner to the optical, bring optoelectronic and electronic components to. The tube 36 and the receiving lug 37 are preferably formed as a unitary precision injection molding component. They have in FIG. 3 has substantially the shape of a box open on one side, which is closed by a cover 43. The receiving lug 37 is, however, considerably narrower than the tube 36 is formed so that at the transition from receiving lug 37 to the tube 36 of the box 43 has a step 59 and the lid has a stage 62nd

p0021The tube 36 has an open at both ends of the central cavity 51, are consecutively placed in which, in Fig 2 seen from left to right:. A photocell 26, a circular ring diaphragm 25, a lens 24, an IR cut filter 52, a further lens 23 with a larger diameter and an angle of 45 ° to the axis 29 of the condenser lens system 23, 24 and the tube 36 inclined transparent plane-parallel plate 30, on the side facing away from the condenser lens system 23, 24 side, with the area of ​​the intersection point of the axis 29 and around a mirror coating 31 is covered. The plate 30 with the mirror coating 31 forms a geometric beamsplitter 28th

p0022In an alternative embodiment, a broken line in FIG. 2 only indicated annular mirror coating 31 'is provided on the opposite side as the mirror 31 surface. It covers those areas of the plate 30, which are transparent when reproduced in full lines embodiments according to FIG. 2, while, is permeable in the alternative embodiment, the central region, which is covered by Fig.2 through the mirror lining 31.

p0023On the side facing away from the condenser lens system 23, 24 side of the beam splitter 28 is a front lens 22, which is installed in an end wall of a dotted line indicated housing 21st

p0024In the lower wall of the tube 36, a collimator lens 32 is arranged below the mirror coating 31 down the cavity 42 of the one-piece with the tube 36 receiving projection 37 adjoins the.

p0025Of the collimator lens 32 has two dichroic deflection mirrors 14 and 15 are disposed at an angle of 45 ° to the axis 16 on the optical axis 16 at a vertical distance. The dichroic mirrors 14, 15 are held on the outer walls of the cavity 42 by suitable brackets 41 (Fig. 2).

p0026Behind the dichroic mirrors 14, 15 of the lens system 23, 24 subsequent to the cavity 42 accommodating spaces 39 and 40, 40 'provided in the direction in which semiconductor radiation sources are mounted green and blue 12 or 13 for example, for the colors.

p0027In alignment with the axis 16, a receiving space 38 is formed for a further semiconductor radiation source 11 below the dichroic mirror 14, which transmits, for example, light in the red spectral range.

p0028Immediately in front of the semiconductor radiation sources 11, 12, 13 are each pinhole 33, 34 and 35 arranged in the receiving cavities 38, 39, 40, concentrically with the axis 16 and the axes 53, 54 of the semiconductor radiation sources 12, 13 are. The openings of the pinhole 38, 39, 40 are at a lower scanning distances A (Fig. 2) to be recognized print marks circularly corresponding rectangular and with larger scanning distances A.

p0029Front of the lens 22 and the housing 21 there is a reading area 18, in which there is a provided with different color markings 19a, 19b and 19c is article 20, whose color marks to be read or recognized by the color sensor arrangement of the invention.

p0030The dichroic mirrors 14, 15, the geometric beam splitter 28 and the IR cut filter 52 have a rectangular shape. The lenses 23, 24 and 32 are of round design and have at two sides of rectangular lugs 23 ', 23' '(Fig. 2 and 4), 24', 24 '' and 32 ', 32' ', but to the optical not contribute figure, but exert a pure support function. All above-mentioned components and the pinhole 33, 34, 35 are here introduced from the open side into retaining grooves 41 and 57 and pushed up to the stop. The cover 43 comprises in the range of the respective optical component corresponding Anschlagausformungen 60 (Fig. 3) adjacent the receiving lug 37 extending into the tube 36, and to the respective optical element, so that after complete insertion of the tube 36 and the receiving approach 37 and the clean closing of the lid 43 a correct position of the optical components is ensured.

p0031The lens 22 is circularly formed and fitted in the wall of the housing is preferably made of metal 21st The tube 36 and the receiving lug 37 are means of fitting holes 61 and not shown, the housing 21 provided fitting pin defines the housing 21 aligned.

p0032The preferably made of glass plate 30 serves only as a support for the deflection mirror coating 31 or 31 'and guarantees the correct position of the deflection mirror in the beam path. According to FIG. 2, the glass plate 30 ends up well below the upper end of the tube to allow a compact relative arrangement of the tube 36 and the objective 22. To avoid annoying reflections, especially the upper end side of the plate 30 is blackened.

p0033The lens system 23, 24 is therefore constructed in two steps because, in the present large lens opening a short focal length is to be realized.

p0034According to FIG. 1, the photo element is connected via a preamplifier 45 16 to a transmitter 27 having a microprocessor 50, an EEPROM 48 and a control panel 49 with function switch, tolerance switches, indicator LED's and a Teach button. The transmitter 27 is powered by a PSU 46th A device connected to the microprocessor 50 output stage 47 provides the outputs of the color sensor array to output terminals Q1, Q2 and Q3.

p0035The signals at the output terminals Q1 to Q3 represent three switching outputs. The color sensor system is overall designed such that can be stored up to three different color pattern per teach-in, which means that the sensor sorts may make with respect to three different colors. The corresponding switching output Q1, Q2 or Q3 is capitalized in accordance with the electronics.

p0036The semiconductor radiation sources 11, 12, 13 are connected to a control electronics 17 which in turn is connected to the microprocessor 50th

p0037According to FIG. 3, the electrical and electronic components shown in FIG. 1 in a purely schematic, expanded block diagram are arranged on only indicated by dashed lines printed circuit boards 44, which are housed in a very compact design to the side of recording approach 37 in spaces 58 of the cuboid housing 21. A further printed circuit board 44 may be disposed immediately behind the photovoltaic element 26 flat to the left in Fig. 2 end face of the tube 36 also according to FIG. 2.

p0038The exact arrangement and dimensioning, particularly of optical and optoelectronic components arising from the following functional description.

p0039The semiconductor radiation sources 11, 12, 13 are sequentially actuated by the control electronics 17, in such a manner that first the semiconductor radiation source 11, a red light beam, the semiconductor radiation source 12, a green light beam, and finally the semiconductor radiation source 13 is a blue light bundle along the axes 16, 53 and 54 emit. By the microprocessor 50 are generated pulse widths less than 10 microseconds.

p0040The light beams successively generated of the semiconductor radiation sources 11, 12 and 13 are steered by means of the dichroic mirrors 14, 15 on the common optical axis 16, it being ensured by means of appropriate length of the receiving cavities 38, 39 and 40, 40 'that of the semiconductor radiation sources 11, 12 and 13 outgoing radiation to the collimator lens 32 equal distances to travel.

p0041The semiconductor radiation sources used 11, 12, 13 have inventively small viewing angle, so that very limited radiation beams are emitted, which is further concentrated by the collimator lens 32 to the mirror coating 31 of the beam splitter 23rd At the beam splitter 28, a deflection of the transmission light beam by 90 ° in the optical axis direction is carried out 29 of the lens 22. In this manner, the lens 22 is a transmitted light beam 55 off.

p0042The collimator lens 32 and the lens 22 form the arranged immediately in front of the semiconductor radiation sources 11, 12, 13 diaphragm 33, 34, 35 on the surface of an object 20 from which is arranged for in the front of the housing 21 reading zone 18 and to be read color markings 19a, 19b and 19c carries.

p0043From the surface of the object 20, the transmitted light beam are scattered back to the lens 22, the part 56 of the entire cross section of the lens 22 engaging receiving the light beam not falling on the central mirror coating 31, passes through the transparent plate 30 and via the lens system 23, 24 incident on the photosensitive element 26, before the aperture 25 is arranged with a square opening. The length of the plate 30 upwards is essentially limited by the upper end of the mirror coating 31, so that a portion of the received light reaches the top of the plate 30 by the lens system 23, 24th

p0044The photoelement 26 is also square thus an electrical signal, which is representative of the received light intensity. The light emitted from the photovoltaic cell 26 electrical signal 45 (Fig. 1) enhanced and a sample &amp; hold stage is first fed and out via an analog-digital converter for the purpose of digital processing in the preamplifier.

p0045In the EEPROM 48, the learned signal level or the calculated from upper and lower threshold values ​​are stored (according to the selected tolerance and hysteresis) and the system software.

p0046By default, the receiver provides for a given gray scale patterns (eg 90% remission) for all three transmitter pulses a same signal level. For any color sample is tested in RUN mode, if the three received signals match the color of the previously taught comparative sample. Match is reached when the current signal level is within a tolerance band. This tolerance band is in accordance with the size of the respective color values, the derived required hysteresis determined (depending on the noise ratios) and the position of the tolerance switch in teach mode.

p0047In RUN mode is normalized to the predetermined to teach mode maximum color value. The normalization to the value determined in the teach process maximum color value provides the following benefits:<ul><li>Signal variations by different sensing planes or by the temperature dependence of the radiant intensity of the individual radiation sources are eliminated unless behave fluctuations for all radiation sources alike.</li><li>Not colored objects or different saturated color values ​​from the normalization result derived directly and be correctly recognized.</li><li>Highest resolution with respect to color saturation.</li><li>Optimal time normalization process.</li><li>Low influence of the noise level.</li></ul>

p0048The color sensor arrangement of the invention is highly durable due to the use of semiconductor radiation sources. Of particular advantage is the adaptation to different tasks planned teach-in button. Due to the collimation of the radiation transmitting a high depth of field is assured. It can be used for the semiconductor radiation sources, high switching frequencies.

p0049By replacement of the lens 22, the color sensor arrangement for at least two detection ranges, for example, 10 mm and 60 mm, are designed.

p0050The auto-collimation invention enables the construction of a very compact sensor with large relative aperture.

p0051The IR cut filter 52 in the receive path (Fig. 2) is used for suppression of extraneous light. For this purpose also, the sequential pulsed operation of the semiconductor radiation sources 11, 12, 13 is advantageous. Expediently takes place according to the invention a logical combination of two or more signal cycles.

p0052The mirror pads 31, 31 'are preferred by way of Teilbedampfung a transparent support (glass plate) realized, wherein the outer contour of the mirror coating 31 establishes the symmetry of the transmission path to the reception path without further suppression.

p0053According to all the optical and opto-electronic components in a single housing (36 tube / receiving lug 37) are attached.

p0054The tube 36 and the receiving lug 37 are manufactured as a one-piece precision injection molding, so that the positions of the components are uniquely determined.

p0055The semiconductor radiation sources 11, 12, 13 and the lenses 32, 23, 24 are fixed precisely by being pressed against a stop by means of displacement noses. The correct position of lenses and mirrors (60 formations) of the lid 43 during the application of the lid controlled and ensured by the special design.

p0056The arranged in front of the semiconductor radiation sources 11, 12, 13 diaphragm 33, 34, 35 are imaged on the object 20, whereby a sharp edge pixel is obtained.

p0057In the alternative embodiment with the annular mirror coating 31 '(Fig. 2) would be the lens with respect to Figure 2 by 90 ° to tilt to the left, the optical axis 29 of the objective lens with the optical axis 16 of the collimator lens to bring 32 is in alignment , In this embodiment, the transmitting light passes at first through the central portion of the transparent plate 30 through while the received light is reflected from the mirror surface 31 'in the lens system 23, 24th

p0058In a preferred ratio of the pupil diameter (objective lens 22 to the collimator lens 32) of 2.5, the use of a geometrical beam splitter 28 in comparison to the physical beam splitter more than 60% of signal gain.

LIST OF REFERENCE NUMBERS

p0059<dl id="dl0002" compact="compact"><dt>11</dt><dd>red semiconductor radiation source</dd><dt>12</dt><dd>green semiconductor radiation source</dd><dt>13</dt><dd>blue semiconductor radiation source</dd><dt>14</dt><dd>dichroic deflecting mirror</dd><dt>15</dt><dd>dichroic deflecting mirror</dd><dt>16</dt><dd>common optical axis</dd><dt>17</dt><dd>control electronics</dd><dt>18</dt><dd>reading Pane</dd><dt>19a</dt><dd>color markings</dd><dt>19b</dt><dd>color markings</dd><dt>19c</dt><dd>color markings</dd><dt>20</dt><dd>object</dd><dt>21</dt><dd>housing</dd><dt>22</dt><dd>lens</dd><dt>23</dt><dd>lens</dd><dt>23 '</dt><dd>rectangular approach</dd><dt>23 ''</dt><dd>rectangular approach</dd><dt>24</dt><dd>lens</dd><dt>24 '</dt><dd>rectangular approach</dd><dt>24 ''</dt><dd>rectangular approach</dd><dt>25</dt><dd>aperture</dd><dt>26</dt><dd>photoelement</dd><dt>27</dt><dd>evaluation system</dd><dt>28</dt><dd>beamsplitter</dd><dt>29</dt><dd>lens axis</dd><dt>30</dt><dd>transparent plane-parallel plate</dd><dt>31</dt><dd>reflective covering</dd><dt>31 '</dt><dd>reflective covering</dd><dt>32</dt><dd>collimator</dd><dt>32 '</dt><dd>rectangular approach</dd><dt>32 ''</dt><dd>rectangular approach</dd><dt>33</dt><dd>pinhole </dd><dt>34</dt><dd>pinhole</dd><dt>35</dt><dd>pinhole</dd><dt>36</dt><dd>tube</dd><dt>37</dt><dd>Up approach</dd><dt>38</dt><dd>receiving space</dd><dt>39</dt><dd>receiving space</dd><dt>40, 40 '</dt><dd>receiving space</dd><dt>41</dt><dd>holding grooves</dd><dt>42</dt><dd>cavity</dd><dt>43</dt><dd>cover</dd><dt>44</dt><dd>circuit board</dd><dt>45</dt><dd>preamp</dd><dt>46</dt><dd>PSU</dd><dt>47</dt><dd>output stage</dd><dt>48</dt><dd>EEPROM</dd><dt>49</dt><dd>Control panel</dd><dt>50</dt><dd>microprocessor</dd><dt>51</dt><dd>cavity</dd><dt>52</dt><dd>IR cut filter</dd><dt>53</dt><dd>axis</dd><dt>54</dt><dd>axis</dd><dt>55</dt><dd>Transmitted light beam</dd><dt>56</dt><dd>Received light beam</dd><dt>57</dt><dd>retaining</dd><dt>58</dt><dd>room</dd><dt>59</dt><dd>step</dd><dt>60</dt><dd>Anschlagausformungen</dd><dt>61</dt><dd>fitting holes</dd><dt>62</dt><dd>step</dd><dt>A</dt><dd>scanning distance</dd><dt>Q1</dt><dd>output terminal</dd><dt>Q2</dt><dd>output terminal</dd><dt>Q3</dt><dd>output terminal</dd></dl>