• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for detecting codes by means of an optical sensor (1), comprising an area camera (7) having a matrix-like arrangement of pixels (7a) and an optical element (8) arranged upstream of the area camera (7), by means of which a code reflected light beams (4) are imaged on the area camera (7). The area camera (7) and the optical element are arranged in a Scheimpflug arrangement. With an evaluation unit (9), output signals of the pixels (7a) of the area camera (7) are evaluated for the decoding of a code. The optical sensor (1) is used for code recognition in the analysis automation.
    公开号:CH706534B1
    申请号:CH00909/13
    申请日:2013-05-03
    公开日:2017-06-15
    发明作者:Wörner Jörg
    申请人:Leuze Electronic Gmbh + Co Kg；
    IPC主号:
    专利说明:

    Description: The invention relates to a method for detecting codes by means of an optical sensor.
    Optical sensors of the type in question are used for the detection of codes, in particular barcodes. Optical sensors of this type forming bar code readers are used in a wide variety of industrial applications, such as, for example, conveyor technology or medical technology, in particular in the field of blood analysis technology.
    Known optical sensors form scanning systems in which a laser beam emitted by a laser diode is deflected periodically via a deflection unit in the form of a motor-driven polygon mirror within a scanning range. Barcodes can then be detected in this scanning area by guiding the laser beam over the bar pattern of the barcode. A disadvantage of such optical sensors is that the laser beam must be aligned exactly with the line patterns of the barcode in order to be able to detect the barcode. In many applications, however, such a defined orientation is not given. Furthermore, the high optomechanical complexity of such optical sensors is disadvantageous. In particular, the parts required for the deflection and alignment of the laser beam are structurally complex. Finally, the sensitive laser diode for generating the laser beam and the moving parts, which provide for the deflection of the laser beam, lead to a low life of the optical sensor and also to a low reliability in the barcode detection.
    Furthermore, optical sensors for detecting codes, in particular barcodes, are known which use a surface camera as a light receiving element. The advantage here is that in this case a stationary lighting unit is sufficient and can be dispensed with a scanner with moving parts for light deflection.
    Problems occur, however, in such optical sensors when barcodes must be read with these in relatively short time intervals, which are formed as bar codes with high densities, that is, a high number of individual bar elements, that is, modules with small module widths. To capture such barcodes, surface cameras with high resolutions, ie a large number of pixels, must be used. However, such areal cameras have relatively low pixel readings as compared to their resolution. This results in correspondingly small image acquisition rates for these high-resolution area cameras, which are defined by the quotient of the pixel read rate and the number of pixels. If now the barcodes to be detected are moved at relatively high speeds relative to the optical sensor, the image acquisition rate of the optical sensor is smaller than the required barcode reading rate, that is, not all the barcodes moved past the optical sensor can be detected.
    Another problem of such optical sensors is that by the imaging properties of a surface camera upstream lens codes are detected only in a very limited distance range, the so-called depth of field, since the code only with the lens sufficiently sharp imaged on the area camera when it is at least approximately in the range of the image width of the lens.
    However, in order to obtain a high availability of the optical sensor, it is necessary that with this codes within a maximum depth of focus range can be detected.
    In order to increase the depth of field in such optical sensors, it is known to provide Fokusverstelleinrichtungen. One possibility of such a focus adjustment device is to change the position of the lens by means of a mechanical actuating unit such as a motor or a piezo element. Depending on the lens position, a code detection can then take place in a specific local area. Another possibility of a focus adjustment device is to use liquid lenses as lenses. By an electrical control of the liquid lens can be directly changed their focal length.
    A disadvantage of the Fokusverstelleinrichtungen is on the one hand, the relatively high design effort. In addition, it is disadvantageous that these focus adjustments are relatively slow, so that a rapid adaptation to different reading distances is not or only insufficiently given.
    The invention has for its object to provide a method in which a sensor is operated with high functionality.
    To solve this problem, the features of claim 1 are provided. Advantageous embodiments and expedient developments of the invention are described in the dependent claims.
    The invention relates to a method for detecting codes by means of an optical sensor. The optical sensor comprises an area camera having a matrix-like arrangement of pixels and an optical element arranged upstream of the area camera, by means of which light beams reflected back from a code are imaged onto the area camera. The area camera and the optical element are arranged in a Scheimpflug arrangement. With an evaluation unit output signals of the pixels of the area camera are evaluated for decoding a code. The optical sensor is used for code recognition in the analysis automation.
    For applications in the field of analysis automation codes with this sensor on sample tubes and / or on a sample tube receiving sample carrier, which is inserted in predetermined insertion positions in an automatic analyzer detected.
    The optical sensor used in the inventive method achieved without the use of moving parts or adjusting devices a large depth of field, within which codes, especially bar codes, can be detected safely and reliably.
    Thus, the optical sensor according to the invention can be used in the field of analysis automation, because there codes must be detected at different distances, and these are also moved relative to the optical sensor, so that high read rates are required in the code detection.
    Since the sample carrier can be optionally introduced into a relatively large number of mutually spaced slots, the codes must be detected when inserted into the slots, with the optical sensor, a correspondingly large depth of field must be covered to the codes Detect slot in one of the slots safely.
    Such a large depth of focus range is achieved solely by the inventive Scheimpflug arrangement of the area camera and the surface camera associated with the optical element.
    Particularly advantageously, the Scheimpflug arrangement is given by the fact that intersect the planes of the surface camera and the optical element and a Scheimpflug level forming imaging plane of the area camera in one point. A code to be detected is disposed inclined to Scheimpflug level and cuts them.
    With this Scheimpflug arrangement, a particularly large depth of focus range is obtained since a code can always be detected on the optical sensor when it intersects the Scheimpflug level. The code can be safely read along its intersection with the Scheimpflug plane, since there a correspondingly sharp image of the code on the surface camera is obtained. Thus, the inventive optical sensor is particularly well suited for detecting one-dimensional codes or very narrow, elongated two-dimensional codes.
    Particularly advantageous is this optical sensor is a stationary code reader.
    The optical sensor is arranged stationary in a specific mounting position relative to the automatic analyzer.
    Another significant advantage of the optical sensor is that even with high barcode rates, that is, with a large number of per unit time entering the coverage area of the area camera codes, especially barcodes, all barcodes can be reliably and reliably detected, namely even if these barcodes are oriented in different directions relative to the optical sensor.
    This is achieved according to the invention by the dynamic fenestration of the area camera. For this dynamic fenestration, windows are selectively defined as subregions of the area camera by means of the switching means, adapted to the conveying speed of the barcodes. In such a windowing, only the pixels within the respective window are read out and used for the image evaluation in the evaluation unit, but not the pixels outside the window. Thus, the image readout rate of the optical sensor compared to the conventional operation of the optical sensor, in which all pixels of the area camera must be read out, be significantly increased. This ensures that the image readout rate of the optical sensor is considerably greater than the barcode rate, which ensures that all of the barcodes moved past the optical sensor can be reliably detected.
    The sizes and locations of the window within the total area of the area camera are adapted to the size and the current orientations of the bar codes relative to the optical sensor such that the barcode currently to be detected can be completely detected with the respective activated window. Conversely, the respective window is dimensioned so that essentially only the barcode to be detected is detected, that is, the respective window is chosen as small as possible in order to ensure the complete detection of the barcode yet. This allows the highest possible image acquisition rate to be obtained.
    Particularly advantageously, this sequence is known by storing the sequence of barcodes to be detected or by determining the time sequence of the barcodes to be detected in a teach-in process. Then, the switching means in the optical sensor can be controlled by an external trigger signal such that the activation of the individual windows in the dynamic fenestration to the transport of the barcodes is tuned so that for each of the immersed in the detection range of the optical sensor barcodes the window with the size and position adapted to the position and orientation is activated.
    Characterized a triggered system is provided with the optical sensor, in which the clock of the dynamic fencing is adapted to the Barcoderate exactly.
    The area camera is particularly advantageously formed by a CCD or CMOS array. With such area cameras, the required high resolutions can be achieved for the detection of high density barcodes.
    In a further advantageous embodiment, the optical sensor has its own lighting unit in the form of an array of LEDs.
    The exposure times of the pixels are particularly advantageously controlled electronically.
    According to a first variant, a so-called rolling shutter can be provided for this purpose. With this Rolling Shutter, the individual pixel lines of the area camera are exposed one after the other, rolling one by one. In order to avoid misdetections, the object to be detected has to be illuminated by the illumination unit for the complete image acquisition time, ie for the time span over which all pixel lines of the area camera are exposed.
    According to a second variant, a so-called global shutter can be provided. With this global shutter all pixels of the area camera are exposed at the same time, which considerably reduces the image acquisition time.
    The invention will be explained below with reference to the drawings. Show it:
    Fig. 1: Schematic representation of an embodiment of the inventive optical sensor.
    Fig. 2: representation of an automatic analyzer with an associated sample carrier.
    3 shows the Scheimpflug arrangement of the area camera and of the optical element of the optical sensor according to FIG. 1.
    4 shows an example of a windowing of the area camera for the optical sensor according to FIG. 1.
    Fig. 1 shows schematically the structure of an embodiment of the optical sensor 1. The components of the optical sensor 1 are integrated in a housing 2. The optical sensor 1 is a stationary code reader, that is, the housing 2 of the optical sensor 1 is fixedly mounted on a receptacle to be able to detect codes in this position. The optical sensor 1 comprises a lighting unit 3, which preferably comprises an arrangement of light-emitting diodes. The light beams 4 emitted by the lighting unit 3 are guided through an exit window 5 in the front wall and serve to illuminate a detection area in which codes can be detected. The codes may generally be formed as one-dimensional or two-dimensional codes. 1 shows an exemplary embodiment of a one-dimensional code in the form of a barcode 6.
    On the barcode 6 incident light beams 4 are reflected back from this and pass through the exit window 5 of the housing 2 on a receiver unit of the optical sensor 1. The receiver unit comprises a surface camera 7 with a matrix-shaped arrangement of pixels 7a, that is light-sensitive receiving elements. Preferably, the area camera 7 is formed in the form of a CMOS array or CCD array.
    The area camera 7 is preceded by a lens 8 as an optical element. This optical element is used to image the light beams 4 onto the area camera 7.
    The illumination unit 3 and the area camera 7 are connected to an evaluation unit 9, which is formed by a microprocessor or the like. On the other hand, the evaluation unit 9 is used to evaluate the output signals of the individual pixels 7a of the area camera 7, that is, to evaluate the image information of a code captured by the area camera 7.
    Due to the contrast structure of the code, which is formed in the present case of light and dark bar elements of the barcode 6, the light beams 4 impinging on the barcode 6 is impressed with a corresponding modulation, so that the light beams 4 on the area camera 7 a the barcode Provide 6 corresponding contrast image, provided that the barcode 6 is located within a certain depth of focus range 10, within which the contrast pattern of the barcode 6 is sufficiently sharp imaged on the area camera 7.
    In the evaluation unit 9, a decoding unit is implemented in the form of software modules, by means of which the barcode 6 is detected on the basis of the image information acquired with the area camera 7, that is to say that the information contained in the bar pattern of the barcode 6 can be detected.
    The optical sensor 1 according to FIG. 1 is used according to the invention in the field of analysis automation. As FIG. 2 shows, sample tubes 12 containing blood or urine samples are stored there on a sample carrier, a so-called rack 11. To identify the samples 12 barcodes 6 are applied to the sample tube. The samples are examined in an automatic analyzer 13. For this purpose, individual racks 11 are inserted into different compartments 14 of the automatic analyzer 13. During the insertion of a rack 11 into a slot 14, the barcodes 6 of the samples on this rack 11 are read by the optical sensor 1. Since the insertion compartment 14, into which a rack 11 is inserted, lies at a different distance from the stationarily arranged optical sensor 1, the optical sensor 1 must be able to read the barcodes 6 within a large depth of focus range 10, ie distance range.
    Such a large depth of focus range 10 is obtained with the Scheimpflug arrangement shown in FIG. 2 of components of the optical sensor 1 according to FIG. 1. In this Scheimpflug arrangement, the plane A, in which the lens 8 of the optical sensor 1 is located, and the plane B, in which the area camera 7 is arranged, are inclined at an angle. With the lens 8, an image of the area camera 7 is generated in a third plane C, which forms a Scheimpflug plane. The planes A, B, C intersect at one point. A barcode 6 to be detected cuts
    权利要求:
    Claims (15)
    [1]
    the plane C and is arranged at an inclination angle to this. The length L of the image of the area camera 7 in the Scheimpflug plane determines the size of the depth of field 10. When the distance within the depth of focus range 10 changes, the barcode 6 travels along the image of the area camera 7 in the Scheimpflug plane. As long as a section line of the barcode 6 is obtained with the image of the area camera 7 in the Scheimpflug plane, the area of the barcode 6 running along this section line is sharply imaged onto the area camera 7, so that the barcode 6 in the evaluation unit 9 is decoded on the basis of this can. In order to increase the image acquisition rate of the optical sensor 1 according to FIG. 1, a dynamic windowing of the area camera 7 is provided, which is illustrated in FIG. 4. Fig. 4 shows a plan view of the photosensitive surface, on which a barcode 6 is shown. Adapted to the position and the size of the barcode 6 depicted on the area camera 7, a window F is defined in the evaluation unit 9 as a subarea of the photosensitive area of the area camera 7. The position of the window F is chosen so that the barcode 6 to be detected lies completely in the window F. Not all pixels 7a of the area camera 7, but only the pixels 7a falling into the window F are then read out to the evaluation unit 9 for evaluation of the barcode 6 and evaluated there. This results in a considerable reduction of the pixels 7a to be evaluated, and consequently a correspondingly faster detection of the barcode 6. In the detection of a sequence of barcodes 6, the windows F are adapted to the sizes and positions of the respective barcodes 6. Thus, very high barcode rates, that is reading speeds, can be achieved. List of Reference Numerals (1) Optical Sensor (2) Housing (3) Lighting Unit (4) Light Beams (5) Exit Window (6) Barcode (7) Area Camera (7a) Pixel (8) Lens (9) Evaluation Unit (10) Depth of field (11) Rack (12) Sample tubes (13) Automatic analyzers (14) Drawer (F) Window Claims
    1. A method for detecting codes by means of an optical sensor (1), comprising an area camera (7) having a matrix-like arrangement of pixels (7a), an optical element arranged upstream of the area camera (7), by means of which light beams (4) reflected back from a code the surface camera (7) and the optical element are arranged in a Scheimpflug arrangement, and with an evaluation unit (9) in which output signals of the pixels (7a) of the area camera (7 ), characterized in that with the optical sensor (1) codes on sample tubes (12) and / or on a sample tube (12) receiving sample carrier, which is inserted in predetermined insertion positions in an automatic analyzer (13) are detected.
    [2]
    2. The method according to claim 1, characterized in that the Scheimpflug arrangement is given by the fact that the planes of the area camera (7) and the optical element and the Scheimpflug level forming image plane of the area camera (7) intersect in a line.
    [3]
    3. The method according to claim 2, characterized in that a code to be detected is arranged inclined to the Scheimpflug level and this cuts.
    [4]
    4. The method according to any one of claims 1 to 3, characterized in that in the optical sensor (1) switching means are provided by means of which a dynamic switching between different windows (F) as subregions of the area camera (7), wherein the pixels ( 7a) within the window (F) are selectively readable and only these selectively read pixels (7a) are used for code detection in the evaluation unit (9).
    [5]
    5. The method according to claim 4, characterized in that the sizes and positions of the window (F) are dimensioned so that a code to be detected within the respective activated window (F).
    [6]
    6. The method according to any one of claims 4 or 5, characterized in that by the dynamic switching between different windows (F), the reading speed of the optical sensor (1) is increased.
    [7]
    7. The method according to any one of claims 4 or 5, characterized in that the switching means are controlled by an external trigger signal.
    [8]
    8. The method according to any one of claims 1 to 7, characterized in that the area camera (7) is formed by a CMOS or CCD array.
    [9]
    9. The method according to any one of claims 1 to 8, characterized in that the exposure times of the pixels (7a) of the area camera (7) are electronically controllable.
    [10]
    10. The method according to claim 9, characterized in that the pixels (7a) of the area camera (7) are exposed line by line rolling one after the other.
    [11]
    11. The method according to claim 9, characterized in that all the pixels (7a) of the area camera (7) are exposed simultaneously.
    [12]
    12. The method according to any one of claims 1 to 11, characterized in that a connected to the evaluation unit lighting unit (3) is provided.
    [13]
    13. The method according to claim 12, characterized in that the illumination unit (3) is formed by an array of light-emitting diodes.
    [14]
    14. The method according to any one of claims 12 or 13, characterized in that the illumination unit (3) in each case over the entire exposure time of the area camera (7) is activated.
    [15]
    15. Method according to claim 1, wherein the optical sensor (1) is a stationary code reader.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2016-10-31| PCAR| Change of the address of the representative|Free format text: NEW ADDRESS: GARTENSTRASSE 28 A, 5400 BADEN (CH) |
    优先权:
    申请号 | 申请日 | 专利标题
    DE201220101809|DE202012101809U1|2012-05-16|2012-05-16|Optical sensor|
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