JP2004110668A - Optical information reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To flexibly respond to the condition of an object to read by enabling the effective setting of a plurality of image processing conditions. <P>SOLUTION: This reader performs a read by taking an image of a moving object by a fixed camera to read the two-dimensional information code attached to the object and performing an image processing by a reading device. A plurality of image processing conditions can be set, and their orders can be preset. A control circuit sets the imaging condition and image processing condition (S1 and S2), and inputs image data to perform the image processing (S3 and S4). When a recognition is successful, information for recognition rate and correctness is stored, and the read result is outputted (S5-S7). When the read is unsuccessful, the processing is repeated by a set frequency, and when the read is unsucessful still, the next image processing condition is read, and the same processing is performed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical information reading device that reads information codes printed by various printing targets and printing methods.
[0002]
[Prior art]
There are various hardware configurations of an optical information reading device that reads, for example, a two-dimensional code as an information code (for example, see Patent Document 1), and there is also a configuration that reads a code of a plurality of standards (for example, , Patent Documents 2 and 3). There is also an apparatus configured to read under different conditions (for example, see Patent Document 4).
[0003]
[Patent Document 1]
JP-A-11-134429
[Patent Document 2]
JP-A-5-258090 [0005]
[Patent Document 3]
JP-A-10-134130
[Patent Document 4]
Japanese Patent Application Laid-Open No. 10-187870
[Problems to be solved by the invention]
However, in the above-described methods, in all of the image processing, a poor specific label that requires processing and processing an image is dealt with by performing a predetermined specific image processing.
[0008]
Until now, if the code printing conditions change, if the code cannot be read, capture the image in anticipation of the change in the next image capture condition, or perform image processing that can absorb the change in the printing conditions as much as possible. Reading was being performed. For this reason, there has been a problem that the reading speed is reduced, and the reading rate is reduced in a line or the like requiring the reading speed. Further, there is no reading device having a function of determining an order from the validity of the reading method.
[0009]
The present invention has been made in view of the above circumstances, and an object of the present invention is to improve reading speed and reading performance in a reading device installed on a line where a code printing condition changes or a line for flowing various products. SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical information reading device that can be achieved.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, the information code is optically photographed and input by the image data acquisition means, and image processing is performed under the set image processing conditions to obtain image data. The demodulation means performs demodulation processing based on the image data. The control means has set a plurality of conditions for obtaining image data by the image data obtaining means in these processing steps, controls the conditions to be applied in a preset order, and sets the conditions under the applied conditions. If the information code cannot be read from the obtained image data by the demodulation processing by the demodulation means, the process is performed under different conditions, and this process is repeated until the information code can be read. With this, a plurality of conditions for acquiring image data can be set in an order corresponding to the state of the information code to be read, so that it is possible to uniformly set even a condition with a low probability of being read. Depending on the case, the condition that can be surely read can be properly used and set, so that a quick and reliable reading process can be performed.
[0011]
According to the second aspect of the present invention, in the first aspect of the present invention, the control means includes the image processing condition as a condition for acquiring image data. Is accepted as it is, and a process enabling reading can be set by changing image processing conditions.
[0012]
According to the third aspect of the present invention, in each of the above aspects, the control means includes a condition defining the brightness of illumination when optically reading the information code as a condition for acquiring image data. By changing the conditions for optically loading the information code, it is possible to set processing for enabling reading.
[0013]
According to the invention of claim 4, in each of the above inventions, the control means sets the number of tries to repeatedly execute the same condition as a condition for acquiring image data until the information of the information code is read by the demodulation means. Because it can be set, even if the object to be read is moving or the information code cannot be read accidentally due to noise or the like, the probability of being able to read correctly can be increased by repeating the operation. .
[0014]
According to the fifth aspect of the present invention, in each of the above aspects, the control unit stores conditions for obtaining image data when the demodulation unit correctly reads the information of the information code, and stores a plurality of conditions. The order is determined based on the obtained data, and the setting for acquiring the image data is performed in the obtained order.Thus, while repeatedly performing the reading operation, the order of the conditions that can be read more correctly is determined. The information code can be obtained automatically, and the information code can be read quickly and accurately according to the conditions for obtaining the obtained image data.
[0015]
According to the invention of claim 6, in each of the above-mentioned inventions, by providing the test means, all of the set conditions for acquiring a plurality of image data can be implemented to read the information code. It is possible to determine the order from the information with the highest degree of accuracy, so that it is possible to perform the reading process of the information code of the actual object to obtain in advance the conditions that allow the most accurate and quick reading. As a result, efficient reading processing can be performed.
[0016]
According to the invention of claim 7, in the invention of claim 6, as the test means, the accuracy of the condition under which the information code can be read by the demodulation means is determined by the accuracy with which the number of error corrections in the reading process is small. Since the criterion of “high” is used, the number of corrections can be reduced when deciding the ranking, and the condition for quick and accurate reading can be automatically obtained.
[0017]
According to the invention of claim 8, in the invention of claim 6, as the test means, the accuracy of the condition under which the information code could be read by the demodulation means, and the degree of coincidence of the function cell of the information code in the read processing. Since the criteria that the higher ones have higher accuracy are used, it is possible to quickly recognize the function cell that is received even when corresponding to the information code when deciding the order. The conditions under which the information code can be read can be automatically obtained.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0019]
FIG. 2 shows an installation environment of the optical information reading apparatus 1. In this embodiment, a two-dimensional code is used as an information code, and the reading apparatus 1 is assumed to be a stationary type. The reading device 1 is configured to input an image captured by the camera 2 serving as an imaging unit, process the image, and perform a reading process.
[0020]
The camera 2 is fixed to the belt conveyor 3 so as to shoot from above, and shoots a two-dimensional information code S printed or affixed on the upper surface of an object 4 such as a product or luggage moving on the belt conveyor 3. Is set to The object 4 flowing on the belt conveyor 3 is assumed to have, for example, a case where the printing condition of the two-dimensional information code S is changed or a case where the printing characteristics of the two-dimensional information code S are different.
[0021]
FIG. 1 shows an electrical configuration of the reading device 1 and the camera 2. The camera 2 is provided with a CCD 5 as an image sensor, a lens 6 for forming an image on the CCD 5, and an LED 7 for illuminating an object to be imaged. ing. An A / D converter 8 for converting a captured image signal into a digital signal and a clock generating circuit (CLK) 9 are connected to the CCD 5. The CLK circuit 9 outputs a clock pulse sufficiently finer than the pulse of the scanning line signal output by the CCD 5 according to the synchronization pulse output from the CCD 5.
[0022]
The reading device 1 is provided with a circuit centered on a control circuit 10 as control means and test means. The control circuit 10 includes a microcomputer, a ROM, a RAM, and other peripheral circuits, and stores a program for a reading process described later in advance. The output terminal of the A / D converter 8 of the camera 2 is directly connected to the control circuit 10 and connected via the binarization circuit 11. The binarization circuit 11 binarizes image data converted into a digital signal with a set threshold value, and the threshold value is set by the control circuit 10 as described later.
[0023]
Further, the output terminal of CLK 9 is directly connected to the control circuit 10 and also connected via the address generation circuit 12. An address memory 13 and an image memory 14 are connected to the control circuit 10. The address generation circuit 12 counts the pulses output from the CLK 9 and generates an address for the image memory 14.
[0024]
The control circuit 10 is connected to an input / output circuit 15 for inputting and outputting operation inputs and setting data from the outside, and a liquid crystal display 16 for displaying images.
[0025]
Next, the two-dimensional information code S directly marked on the object 4 by the laser marker will be described. As shown in FIG. 3A, in the marking with the laser marker, the diameter and depth of the circular cell of the dot to be printed change depending on the fluctuation or variation of the applied voltage of the laser light source or the material of the object to be marked. As a result, even if marking is performed under the same conditions, a difference occurs in print quality. Further, as shown in FIG. 3B, depending on the lighting conditions and the material of the printing target, the image taken by the camera 2 may be in a state where the portion where the dot is taken and the portion where the dot is not taken are reversed. .
[0026]
As an index indicating the accuracy of recognition of the two-dimensional information code S, there is a function cell provided in the two-dimensional information code S. For example, in the QR code shown in FIG. 4A, rectangular marks arranged at three corners are set as function cells. In the data matrix code represented by the data matrix code (b) in FIG. 3, two orthogonal sides are set as function cells. Therefore, since this functional cell can be regarded as a known shape, as shown in FIGS. 5A and 5B, it is relatively easy to determine how much the obtained image data matches. Yes, and can be set as one index.
[0027]
Next, the operation of the present embodiment will be described with reference to the flowchart of the reading processing program of FIG.
That is, in this embodiment, a plurality of image processing conditions are set as conditions for acquiring image data. That is, a plurality of conditions for image processing of the image of the two-dimensional information code S photographed by the camera 2 are set without changing the conditions for photographing by the camera 2. The image processing conditions include, for example, a threshold setting condition for binarizing the A / D converted image data as described above, a change in the degree of blurring of the image data, and expansion and contraction of the image data. The setting of the conditions for the filtering process is performed.
[0028]
FIG. 6 shows image data when the blurring processing is performed. As shown in FIG. 7A, the two-dimensional information code S marked with a laser marker may have a small cell size, in which case a gap is formed because the distance between the cells is constant. It becomes like. By subjecting this to a blurring process, each cell is enlarged, thereby obtaining a connected linear pattern.
[0029]
When starting the reading processing program shown in FIG. 7, the control circuit 10 first sets imaging conditions (step S1). As the imaging conditions, for example, lighting conditions when the two-dimensional information code S is read by the camera 2 and other imaging conditions are set.
[0030]
Next, the control circuit 10 sets image processing conditions (step S2). Here, the control circuit 10 is configured to read and set, from data of a plurality of image processing conditions stored in an internal memory (not shown), a condition designated as a condition to be used first. Next, when the control circuit 10 starts reading the two-dimensional information code S, the control circuit 10 captures an image captured by the camera 2 (step S3), converts the image into a digital signal, and processes the image under the set image processing conditions. Is performed (step S4).
[0031]
Thereafter, the control circuit 10 performs a demodulation process based on the image data subjected to the image processing. The control circuit 10 determines whether or not the two-dimensional information code S has been correctly recognized by the demodulation process (step S5). If so, the determination is "YES" and the information on the recognition rate and the accuracy of the image processing condition at that time is stored (step S6).
[0032]
In this case, as described above, the recognition rate and the accuracy information are represented by an index using the degree of coincidence of the function cell as a scale, or the number of times of error correction when reading a certain information code. Can be represented by an index having a scale of, or the scale can be defined by another method.
[0033]
The control circuit 10 stores the read result and outputs the data to the input / output circuit 15 and the liquid crystal display 16 to transmit data and perform a display operation (step S7). Thus, a series of reading processing ends.
[0034]
On the other hand, if the code information could not be recognized in step S5 (determined as "NO" in step S5), first, the recognition rate / accuracy information in the case where recognition was not possible was performed in the same manner as described above. An index is obtained and stored (step S8). Thereafter, the control circuit 10 determines whether or not the number of image processings set in advance for the image processing conditions is equal to the number of tries for actually performing image processing for recognition (step S9). If not (determined as "NO"), the process returns to step S3 to repeat the above-described image processing and recognition processing.
[0035]
If "YES" is determined in step S5 before the number of tries reaches the set number, that is, if the recognition is correctly performed, information on the recognition rate and accuracy at that time is stored ( Step S6) and end through step S7. If the number of tries reaches the set number before the correct recognition is obtained, the control circuit 10 determines “YES” in step S9 and proceeds to step S10.
[0036]
The control circuit 10 performs a reading process on the image processing condition set to the next priority (step S10). If there is an image processing condition that has been set, “YES” is determined in the step S11, this is set as a new image processing condition, and the process returns to the step S2 to execute the above-described processing steps (steps S2 to S7, S8). , S9) are repeatedly executed.
[0037]
If the two-dimensional information code S included in the captured image is correctly recognized under the newly set image processing conditions, the process ends through steps S5 to S7 in the same manner as described above, but the number of trials is set. If the reading is not performed correctly even if the number of times has been reached, the control circuit 10 repeats the processing until there is no more image processing condition to be read in step S10.
[0038]
Thereafter, if the reading process has not been correctly performed to the end, the control circuit 10 determines "NO" in step S11, stores that reading was impossible, and stores a predetermined reading disabled time. (Step S12), and the process ends.
[0039]
As described above, when the reading process for the captured two-dimensional information code S is completed, the two-dimensional information code S attached to the next object 4 is captured, and the same process as described above is repeated again. become.
[0040]
Now, when performing the processing as described above, the image processing conditions read out by the control circuit 10 are prioritized. For example, the two-dimensional information code assigned to the object 4 moving on the belt conveyor 3 from now on In accordance with the printing state of S, conditions under which reading can be performed quickly can be determined in advance and set in that order.
[0041]
As a result, the image processing conditions can be changed in accordance with the priority order each time, so that flexible image processing conditions can be set in accordance with the print quality. As a result, it is possible to perform a quick and accurate reading process, and it is not necessary to set the moving speed of the belt conveyor 3 slower than necessary by increasing the reading speed.
[0042]
(Second embodiment)
FIGS. 8 and 9 show a second embodiment of the present invention. The difference from the first embodiment is that a learning processing function is added. FIG. 8 shows a reading processing program for performing the learning processing, and is a flowchart in which a learning processing S13 is added as the last step of the processing shown in FIG.
[0043]
In this learning processing step S13, processing as shown in FIG. 9 is executed. The control circuit 10 reads out the stored results as information on the recognition rate and accuracy for each image processing condition at the time of performing the reading process (Step P1). Subsequently, the control circuit 10 calculates the recognition rate / accuracy of the read result data with respect to the number of executions (step P2), and ranks the image processing conditions in the descending order of the recognition rate / accuracy from the obtained result. Attached and arranged (step P3). Thereafter, the order in which the image processing conditions with the ranks are to be read in the next reading process is set (step P4).
[0044]
As a result, a new order is set with respect to the previously set priority order, so that even if the optimum image processing conditions are shifted due to changes in printing conditions and the like while the reading process proceeds. Following this, the reading process can be performed under the most appropriate conditions.
[0045]
(Third embodiment)
FIG. 10 shows a third embodiment of the present invention. The difference from the first embodiment is that a plurality of image processing conditions to be set are tested and the priorities are determined according to the read recognition rate. Just added a test function that can be set.
[0046]
For example, when moving the object 4 under new reading conditions to the belt conveyor 3, a plurality of candidate image processing conditions are input in advance, and a test program shown in FIG. Image processing conditions can be set in descending order.
[0047]
When the test program is started, the control circuit 10 executes steps S1 to S4 in the same manner as the reading process. Thereafter, the control circuit 10 performs the process of step S6, and stores information on the recognition rate and accuracy of reading according to the image processing conditions set at that time. Then, it is determined whether or not the process has been executed the set number of times (step S14). If “NO”, the process returns to step S4 to repeatedly execute the image processing.
[0048]
If “YES” is determined in step S14, the control circuit 10 determines whether the next image processing condition is set (step S15). If “YES”, the control circuit 10 determines the next image processing condition. After reading (step S16), the process returns to step S2. Similarly, image processing is executed based on the read image processing conditions, and information on the recognition rate and accuracy at that time is obtained (steps S2 to S4, S6, and S14).
[0049]
If there are no more image processing conditions to be read next, the control circuit 10 determines “NO” in step S15, and based on the recognition rate and accuracy data of the plurality of image processing conditions obtained so far. Then, an order setting process is performed (step S17). This is a process similar to the learning process described in the second embodiment, in which image processing conditions with a high recognition rate or high accuracy are set with high priority, and are read out in that order during the actual reading process. Perform the setting process.
[0050]
As a result, even in the case of printing conditions in which it is difficult to set image processing conditions in advance, it is possible to automatically obtain the conditions that allow the most accurate and prompt reading processing by actually executing the test program. By performing the actual reading process in accordance with this, a quick and accurate reading process can be performed.
[0051]
(Fourth embodiment)
FIG. 11 shows a fourth embodiment of the present invention. What differs from the first embodiment is that not only the above-described image processing conditions but also the conditions for acquiring image data, that is, the recognition processing conditions are used. Also, the conditions at the time of shooting are taken into account. That is, the photographing conditions include, for example, conditions for illuminating the object 4 with the LED 7 provided in the camera 2. Depending on the printing conditions of the two-dimensional information code S attached to the object 4 or its surface, the degree of brightness of the illumination may slightly affect reading. In response to this, it is possible to cope with this by changing the image processing conditions. However, changing the brightness of the illumination as a photographing condition may contribute to quick reading.
[0052]
In this embodiment, paying attention to such photographing conditions, it is possible to set a recognition processing condition in consideration of photographing conditions in addition to image processing conditions. When starting the reading processing program, the control circuit 10 first reads and sets the recognition processing conditions (step S18). Subsequently, image data is input and image processing is performed (steps S3 and S4), and information on the recognition rate and accuracy under the recognition processing conditions at that time is obtained and stored (step S6).
[0053]
The control circuit 10 repeats steps S18, S3, S4, S6, and S16) until the set number of times of reading processing under the set recognition processing conditions is performed. If “YES” in step S16, the next step is performed. If there is a recognition processing condition, it is read and set (steps S14 and S19), and the above-described processing is repeatedly executed.
[0054]
When the control circuit 10 determines "NO" in step S14, the control circuit 10 performs an order setting process in step S17 and ends the program. As a result, the reading process can be performed in a flexible manner while automatically setting the recognition process conditions that allow the most accurate and quick recognition process.
[0055]
The present invention is not limited to the above embodiment, but can be modified or expanded as follows.
The information code is not limited to the two-dimensional code, but may be a barcode. Further, in the two-dimensional code, a two-dimensional code other than the QR code and the data matrix code can be targeted.
[Brief description of the drawings]
FIG. 1 is an electrical configuration diagram showing a first embodiment of the present invention. FIG. 2 is a schematic diagram showing an arrangement relationship of an entire configuration when performing a reading process. FIG. 3 is a display example of a two-dimensional information code. FIG. 5 is a diagram for explaining function cells of a two-dimensional information code. FIG. 5 is a diagram for explaining the degree of coincidence of function cells. FIG. 6 is an operation explanatory diagram when a blurring process is performed. 8 is a diagram corresponding to FIG. 7 showing a second embodiment of the present invention; FIG. 9 is a flowchart of a learning processing program; FIG. 10 is a diagram corresponding to FIG. 7 showing a third embodiment of the present invention; FIG. 7 corresponding to FIG. 7 showing a fourth embodiment of the invention.
1 is a reading device, 2 is a camera (imaging means), 3 is a belt conveyor, 4 is an object, 5 is a CCD, 7 is an LED (lighting means), 10 is a control circuit (control means and test means), 11 is binary Reference numeral 12 denotes an address generation circuit, 13 denotes an address memory, 14 denotes an image memory, 15 denotes an input / output circuit, and 16 denotes a liquid crystal display.

Claims (8)

Image data obtaining means for optically capturing and inputting an information code and performing image processing under set image processing conditions to obtain image data;
Demodulation means for performing demodulation processing based on image data image-processed by the image processing means;
A plurality of conditions for acquiring the image data including the image processing conditions in the image data acquiring means can be set, and a plurality of conditions set until the information of the information code can be read by the demodulation processing by the demodulation means. Control means for sequentially executing conditions for acquiring image data in accordance with a priority order. The optical information reading device according to claim 1,
The optical information reading apparatus, wherein the control means includes the image processing condition as a condition for acquiring the image data. The optical information reading device according to claim 1 or 2,
The optical information reader according to claim 1, wherein the control unit includes a condition for defining the brightness of illumination when the information code is optically read, as a condition for acquiring the image data. The optical information reading device according to any one of claims 1 to 3,
The control unit is configured to be able to set the number of tries to repeatedly execute the same condition as a condition for acquiring the image data until the information of the information code is read by the demodulation unit. Optical information reader. The optical information reading device according to any one of claims 1 to 4,
The control means stores a condition for acquiring the image data when the information of the information code is read by the demodulation means, and determines an order for a condition for acquiring a plurality of image data, An optical information reading apparatus, wherein the image data obtaining means is set to obtain the image data in the order obtained. The optical information reading device according to any one of claims 1 to 5,
Test means for executing all the conditions for obtaining the set of image data and determining the order of the conditions under which the information code was successfully read by the demodulation means from the one with the highest accuracy. An optical information reading device comprising: The optical information reading device according to claim 6,
The optical information is characterized in that the test means uses the criterion that the accuracy of the condition under which the information code was read by the demodulation means is high, and that the accuracy of a condition with a small number of error corrections in the reading process is high. Reader. The optical information reading device according to claim 6,
The test means uses a criterion that the accuracy of a condition under which the information code can be read by the demodulation means is determined based on a condition that the degree of coincidence of the function cell of the information code in the reading process is high. Optical information reader.

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