JPS6385991A - Bar code reader - Google Patents

Abstract

PURPOSE:To correctly read a bar code as a whole even when a defect is produced in a part of the bar code, to reduce the burden of an operator and to improve the reliability by providing a two-dimensional optical reading sensor for reading the two dimensional picture information of the bar code. CONSTITUTION:The two-dimensional picture information of the bar code 15 forms an image on the two dimensional optical reading sensor 18. The light receiving surface of the two dimensional optical reading sensor 18 has a square form and its X axis direction and its Y axis direction correspond to the horizontal direction and the vertical direction of a reading window 14. The two dimensional optical reading sensor 18 has linear photosensors consisting of many photodetectors linearly arranged in the X axis direction which are arranged throughout plural lines in the Y axis direction. The image formed two dimensional picture information of the bar code is transformed to an electric signal in the respective photodetectors. A data selection circuit 26 sequentially reads line data stored in a picture data memory 23 corresponding to the number of characters in the sequence from the nearest number to a preset prescribed number of the number of the inputted respective characters in the form of an original line data signal and transmits to a decoder circuit 27.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a barcode reading device that reads barcodes indicating product codes etc. attached to products, and particularly relates to a barcode reading device that reads barcode image information two-dimensionally. This invention relates to a barcode reading device that reads and analyzes barcodes.

[Prior art] For example, it is connected to an electronic cash register and is held and handled by an operator with one hand as one of the barcode reading devices that read the barcode attached to each sales product and convert it into code data such as a product code. There are barcode reading devices equipped with wands that can be used to read barcodes.

As is well known, this hand-held barcode reader is equipped with a light source and a linear photosensor in which a plurality of light-receiving elements are arranged one-dimensionally in a case, and the light output from the light source is output from the reading window of the case. , is reflected by the barcode surface located close to the outside of the reading window, and this reflected light is input to the linear photosensor as image information of the barcode. In this case, the reading window is pressed against the barcode attached to the product so that the array direction of the linear photosensors matches the array direction of each bar of the barcode. Therefore, a bright and dark striped pattern corresponding to the arrangement of each bar of the barcode is projected onto the linear photosensor. As a result, this linear photosensor outputs an analog line data signal whose signal level changes depending on the installation position of each light receiving element constituting the linear photosensor.

This analog line data signal is converted into a binary code of H level or L level by a quantization circuit and converted into digital line data. Then, a decoder circuit converts this line data into code data consisting of numbers or symbols such as a product code corresponding to the barcode.

[Problems to be Solved by the Invention] However, the barcode reading device configured as described above also has the following problems.

In other words, since the width of the light-receiving surface of each light-receiving element constituting the linear photosensor housed in the case is very small, the width of the barcode input to this light-receiving surface in one direction is 0. It is about .03~1.00■. Therefore, the code data is determined based only on the image information having a width of 0.03 to 1.00 mm out of all the bar code image information attached to the product.

゛ On the other hand, some of the barcodes attached to each product are poorly printed or printed on poor quality wrapping paper, resulting in voids within each bar that makes up the barcode. There may be spots between the bars. There are also products in which the entire barcode printed product is covered with transparent wrapping paper such as cellophane paper. In such a barcode, specular reflection may occur partially due to the transparent wrapping paper that covers the surface. Void like this.

If spots, specular reflections, etc. occur, there is a possibility that the voids, spots, specular reflections, etc. will be included in the image information having a width of 0.03 to 1.00 mm read by the linear photosensor.

If such a defect is introduced, a reading error may occur or the code may be converted into incorrect code data.

If a reading error occurs, the operator shifts the position of the barcode on the reading window of the case and tries again. As a result, the burden on the operator increases, and there is a concern that products different from those for sale may be registered.

Also, of course, if the direction of the linear photosensor and the reading direction of the barcode deviate greatly and the barcode falls outside the reading area of the linear photosensor with a width of 0.03 to 1.00m +++, a reading error occurs. becomes.

The present invention provides a two-dimensional optical reading sensor, and by reading the two-dimensional image information of the barcode with the two-dimensional optical reading sensor, even if a defect occurs in a part of the barcode, the entire barcode can be correctly read. It is an object of the present invention to provide a barcode reading device that can read barcodes, reduce the burden on an operator, and improve reliability.

[Means for Solving the Problems] As shown in FIG. 1, the barcode reading device of the present invention uses a linear photosensor in which a plurality of light receiving elements are linearly arranged in the A two-dimensional optical reading sensor 2 that reads two-dimensional image information of a barcode in which a plurality of barcodes 1 and 1 are arranged in the Y direction of a reading window and each bar input from the reading window is approximately parallel to the Y axis; Each line data read by each linear photosensor 1 of the reading sensor 2 is
A quantization circuit 3 for value encoding and an image data memory 4 for storing each line data binary-encoded by the quantization circuit 3 are provided, and a character number counter 5 outputs the data from the quantization circuit 4. The number of characters indicating the number of level changes in each line data is counted, and each line data stored in the image data memory 4 by the data selection readout circuit 6 is counted by the character number counter 5. They are read out sequentially in order of proximity to the predetermined value. The decoder circuit 7 converts each line data read out by the data selection readout circuit 6 into code data corresponding to a barcode.

In another invention, the two-dimensional optical reading sensor 2. A quantization circuit 31, an image data memory 4, and a decoder circuit 7 are provided, and a Y-axis correction circuit 8 calculates all the output lines of each data at the same X coordinate position in each line data output from the image data memory 4. The data is added together to form one corrected line data, and the line data output from the Y-axis correction circuit 8 is sent to the decoder circuit 7.

Furthermore, in another invention, the two-dimensional optical reading sensor 2. A quantization circuit 31, an image data memory 4, and a decoder circuit 7 are provided, and an X-axis phase correction circuit 9 determines each reference X-coordinate position where the signal level first changes in each line data output from the image data memory 4. All X-coordinate positions of each line data are shifted and corrected so as to match the reference X-coordinate position of the reference line data, and each line data output from this X-axis phase correction circuit 9 is sent to the decoder circuit 7. It is something.

[Operation] With the barcode reading device configured as described above, the two-dimensional image information of the barcode is read by each linear photosensor constituting the two-dimensional optical reading sensor, and is binary encoded as each line data. and is temporarily stored in the image data memory. At the same time, the number of characters in each line data is counted by a character number counter. Then, each line data stored in the image data memory is read out in the order in which the number of characters is closer to a predetermined value, and converted into code data corresponding to a bar code by a decoder circuit.

Here, if the type (number of digits) of each code data corresponding to each barcode is the same, the number of characters in the barcode is constant, so if the number of characters is taken as a predetermined value, the number of characters is is close to a predetermined value, that is, normal line data is preferentially converted into code data by the decoding circuit. Line data with an abnormally large number of characters or line data with an abnormally small number of characters due to the aforementioned defects are finally input to the decoder circuit.

Another effect of the invention is that each data at the same X coordinate position in each line data stored in the image data memory is added over all line data. Each piece of data at the same X-coordinate position is added in the Y-axis direction, that is, in the direction parallel to the bar. Therefore, even if the above-mentioned partial defect exists in the middle of the Y-axis direction, the influence caused by the defect on the added data is small. As a result, correct code data can be obtained by decoding the line data after addition.

Furthermore, another function of the invention is that each reference X coordinate position where the signal level first changes in each line data stored in the image data memory is detected, and each reference X coordinate position is used as the reference line data. Each line data is shifted in the X-axis direction so as to match the reference X seat ridge position.

Therefore, even if there is some deviation between the Y-axis direction of the reading window and the bar code direction, this deviation will be corrected.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a wand portion held by an operator constituting the barcode reading device of the embodiment. A light source 12 formed of, for example, a light emitting diode (LED), which outputs a near-red light beam, is disposed inside the case 11, and a light beam 13 output from the light source 12 is outputted from the reading window 14 to the outside of the case 11. , is diffusely reflected by the barcode 15 attached to the product.

Then, the diffusely reflected light ray 13 enters the case 11 again through the reading window 14, and is inputted to the two-dimensional optical reading sensor 18 via the reflecting mirror 16 and the condensing lens 17.

That is, the two-dimensional image information of the barcode 15 forms an image on the two-dimensional optical reading sensor 18.

The light receiving surface of this two-dimensional optical reading sensor 18 has a rectangular shape, and its X-axis direction and Y-axis direction correspond to the horizontal and vertical directions of the reading window 14. The two-dimensional optical reading sensor 18 is a linear photosensor in which a large number of light-receiving elements are linearly arranged in the X-axis direction, which are arranged in multiple rows in the Y-axis direction. In the embodiment, one linear photosensor is formed of 120 light receiving elements, and these linear photosensors are arranged in 80 rows in the Y-axis direction.

That is, this two-dimensional optical reading sensor 18 has a 120
It is made up of 80-9800 light receiving elements.

The two-dimensional image information of the barcode imaged on the light-receiving surface of the two-dimensional optical reading sensor 18 is converted into an electrical signal by each light-receiving element. The converted electric signal is sequentially outputted as a serial line data signal for each light receiving element for each linear photosensor by an output control section (not shown), and then sent to the amplifier 1.
After being amplified in step 9, the signal is input to a sample hold circuit 20 shown in FIG. 3 provided outside the case 11. The line data signal before being input to the sample bold circuit 20 is separated by a reset signal for each light receiving element.
It is intermittent for each light receiving element. Therefore, the sample bold circuit 20 removes the reset signal component and converts it into an electrical signal having only the image information (pattern) component of the barcode 15. The sample and hold circuit 20 removes the reset signal component, and the stepwise line data signal is smoothly shaped by the next low-pass filter 21. Then, the next stage quantization circuit 22 performs binary encoding of H level or L level.

The binary encoded line data signals of each linear photosensor are sequentially stored in the image data memory 23. This image data memory 23 has storage elements arranged in the same manner as each light receiving element of the two-dimensional optical reading sensor 18, and as shown in FIG. 4, each storage element 'G! (XO, YO) to CXN
, YM) The teno coordinate numbers are attached. The H level or L level data corresponding to each light receiving element included in each line data signal is stored in each line data memory 24 whose X coordinate changes from 0 to N and whose Y coordinate value is common. In addition, in the example, it is N-199,
It is M-79. Therefore, the two-dimensional image information of the barcode is stored in this image data memory 23.

Further, the signal level of the line data signal changes in synchronization with the operation in which each data value of each binary encoded line data signal sequentially output from the quantization circuit 22 is sequentially stored in the image data memory 23. A character number counter 25 counts the number of characters, that is, the number of characters. The counted number of characters of each line data signal is stored in the character number counter 25 until the data of all the line data signals is stored in the image data memory 23.

When all the line data is stored in the image memory 23, the number of characters of each line data signal stored in the character number counter 25 is sent to the next data selection readout circuit 26. The data selection readout circuit 26 selects the line data stored in the image data memory 23 corresponding to the input character number in the order of the closest to a predetermined number of input characters in the form of the original line data signal. The data are sequentially read out and sent to the decoder circuit 27. Note that the predetermined number is set to, for example, a number corresponding to when the barcode 15 is correctly read.

The line data signal output from the data selection readout circuit 26 is converted into code data corresponding to the barcode 15 by a decoder circuit 27. The converted code data is then incorporated into a transmission message by the formatting circuit 28 and input to the electronic cash register 30 via the interface circuit 29.

In the barcode reading device configured as described above, the reading process of the barcode 15 when the barcode 15 is covered with transparent cellophane paper and specular reflection occurs will be explained with reference to FIGS. 5 and 6. do. FIG. 5 is a diagram showing the contents stored in the image data memory 23 when a barcode 15 with oblique specular reflection is read. In other words, the part of the bar code shown in black is the H level.
The area between the bar and the part shown in white is at L level. Also within this image data memory 23, the specular reflection portion 32 remains as a white L level.

In this case, the barcode exists in the coordinate range of X-20 to 100 and Y-10 to 69. therefore,
As shown in signal a of FIG. 6, Y-10 to Y-19 and Y
Each line data signal between -40 and 69 is reflected by the specular reflection section 3.
It becomes a normal signal that is not affected by 2.

In this case, the number of characters is 17.

In addition, for example, Y-2, which includes the specular reflection part 32 and which is already shown in the signal
Since the line data signal No. 2 and the Y-35 line data signal shown as signal C do not include the image information of all the barcodes 15, the number of characters is 13 and 9, respectively. Therefore, if the predetermined number of data selection readout circuits 26 is set to a value close to 17, a normal line data signal indicated by signal a is transmitted to the next decoder circuit 27 with priority. As a result, in the decoder circuit 27,
Since normal line data signals that do not cause reading errors are input with priority, correct code data can be obtained in a short time, and the electronic cash register 31
The correct code data is entered immediately.

In addition, if a spot occurs between the bars of barcode 15 where a void occurs, the number of characters will increase and deviate from the predetermined number, so the line data signal in this part will be the normal line data, and the line data signal will start after the signal. Decoder circuit 27
is input to. Therefore, the same result as in the case of specular reflection is obtained.

In this way, even if specular reflection, voids, or spots occur, the barcode 15 is immediately converted into accurate code data and input to the electronic cash register 31. As a result, it becomes possible to omit the operator's re-reading operation, which reduces the burden on the operator, and also prevents the barcode from being converted into incorrect code data, thereby improving the reliability of the entire apparatus.

FIG. 7 is a block diagram showing a barcode reading device according to another embodiment of the present invention. Components that are the same as those in FIG. 3 are designated by the same reference numerals, and explanations of overlapping components will be omitted. In this embodiment, each line data signal output from the image data memory 23 is input to a Y-axis correction circuit 33. This Y-axis correction circuit 33 adds each data at each -X coordinate position in the line data signals sequentially outputted from the image data memory 23 over all the line data signals. Then, this added line data signal is binary encoded by a quantization circuit (not shown) and output as a new combined line data signal. The line data signal output from the Y-axis correction circuit 33 is converted into code data corresponding to the barcode 15 by the decoder circuit 28.

In the barcode reading device configured as described above, a reading process for a barcode 15 that is subjected to diagonal specular reflection will be described with reference to FIGS. 8 and 9. In this case, the specular reflection section 3 in the image data memory 23
4 covers the barcode as shown in FIG. 8, so Y-10 to Y-69 are
There is no normal line data among the line data up to this point. However, if the Y-axis correction circuit 33 adds these line data signals with missing portions in the specular reflection section 34 while synchronizing the X-axis, and then binary-encodes them again through a quantization circuit (not shown). , as shown in the d signal in FIG. 9, one normal line data signal is obtained in which the missing data are synthesized so as to compensate for each other. Therefore, a correct line data signal is sent from the Y-axis correction circuit 33 to the next decoder circuit 27.

In this way, in this embodiment, even if the mirror reflection surface crosses the barcode 15 diagonally and no normal line data is obtained, all line data is
By combining in the axial direction, one correct line data can be obtained. Therefore, the probability of reading errors occurring can be reduced, the burden on the operator can be reduced, and the work efficiency of the entire reading operation can be improved.

FIG. 10 is a block diagram showing a barcode reading device according to yet another embodiment of the present invention. Components that are the same as those in FIG. 3 are given the same reference numerals and redundant explanations will be omitted. In this embodiment, each line data signal output from the image data memory 23 is input to an X-axis phase correction circuit 35. This X-axis phase correction circuit 33 is connected to the image data memory 2
Shift all the X-coordinate positions of each line data signal so that each reference X-coordinate position where the signal level first changes in the line data signals sequentially output from 3 coincides with the reference X-coordinate position of the line data signal that is the reference. to correct. Each line data signal after the shift correction is then transmitted to the decoder circuit 27 at the next stage.

In the barcode reading device configured in this way,
It is assumed that the reading window 14 of the case 11 is pressed against the barcode 15 with the Y-axis direction of the reading window 14 and the bar direction of the barcode 15 being shifted from each other. In this case, the entire barcode is stored in the image data memory 23 in an inclined state, as shown in FIG. therefore,
As shown in FIG. 12, a line data signal indicated by a signal g located at the top in the Y-axis direction and a signal j located at the bottom
A data dropout occurs in the line data signal shown by . Further, even if there is no data missing, the reference X coordinate at which the signal level first rises from the L level to the H level in each line data parallel to the X axis differs depending on each line data. For example, Y indicated by a traffic light
The reference X coordinate of the line data signal 11 is X-19, and the reference X coordinate of the line data signal YB2 indicated by signal i is X-15.

In this case, if the reference line data signal is the Y-19 line data signal, 4 is added to each X coordinate of the Y-64 line data signal, and the entire line data signal is shifted to the right by 4. . In this way, all the line data signals are shifted and corrected in the X-axis direction by respective amounts so that the reference X coordinates coincide with the reference X-19. As a result, the X coordinates of all line data signals are
-19.

Note that X-axis correction is not performed from the beginning for line data signals in which data at the upper and lower ends are missing.

Even if the barcode 15 is read at an angle in this manner, it is corrected by the X-axis phase correction circuit 35, so that it is transmitted to the decoder circuit 27 without causing a reading error. Further, conversion into code data by the decoder circuit 27 becomes easier. Therefore, as in the previous embodiment, the burden on the operator can be reduced and the efficiency of the reading operation can be improved.

Note that the present invention is not limited to the embodiments described above. For example, each line data signal output from the image data memory 23 is matched in phase in the X-axis direction by the X-axis phase correction circuit 35, and then combined in the X-axis direction by the Y-axis correction circuit 33 to form one line. It may also be input to the decoder circuit 27 as a data signal. In this case, the barcode will be converted into code data more accurately and more quickly.

[Effects of the Invention] As described above, according to the present invention, a two-dimensional optical reading sensor is provided, and two-dimensional image information of a barcode is read by the two-dimensional optical reading sensor. Therefore, even if a defect occurs in a part of the barcode, the entire barcode can be read correctly, reducing the burden on the operator and improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the present invention, FIGS. 2 to 6 are diagrams showing a barcode reading device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the wand portion, and FIG. 3 is a block diagram showing the whole, FIGS. 4 and 5 are diagrams showing the image data memory, FIG. 6 is a time chart showing the operation, and FIGS. 7 to 9 are diagrams showing other embodiments of the present invention. 7 is a block diagram showing the whole, FIG. 8 is a diagram showing the image data memory, FIG. 9 is a time chart showing the operation, and FIG. FIG. 12 shows a barcode reading device according to still another embodiment of the present invention, FIG. 10 is a block diagram showing the whole, FIG. 11 is a diagram showing an image data memory, and FIG.
FIG. 2 is a time chart showing the operation. 11...Case, 12...Light source, 13...Light ray,
14...reading window, 15...barcode, 18...
Two-dimensional optical reading sensor, 20... Sample hold circuit, 22... Quantization circuit, 23... Image data memory, 24... Line data memory, 25... Character number counter, 26...・Data selection read circuit, 2
7... Decoder circuit, 31... Electronic cash register, 32° 34... Specular reflection section, 33... Y-axis correction circuit, 35... X-axis phase correction circuit.

Claims (3)

[Claims] (1) A plurality of linear photosensors each having a plurality of light receiving elements arranged linearly in the X direction of the reading window are arranged in the Y direction of the reading window, and each bar input from the reading window is A two-dimensional optical reading sensor that reads two-dimensional image information of a barcode approximately parallel to the Y axis, and a quantization circuit that binary encodes each line data read by each linear photosensor of this two-dimensional optical reading sensor. , an image data memory for storing each line data binary encoded by the quantization circuit, and a character for counting the number of characters indicating the number of level changes in each line data output from the quantization circuit.
a number counter, a data selection readout circuit that sequentially reads each line data stored in the image data memory in the order in which the number of characters counted by the character number counter is close to a predetermined value; 1. A barcode reading device comprising: a decoder circuit for converting each line data read out into code data corresponding to the barcode. (2) A plurality of linear photosensors each having a plurality of light receiving elements arranged linearly in the X direction of the reading window are arranged in the Y direction of the reading window, and each bar input from the reading window is A two-dimensional optical reading sensor that reads two-dimensional image information of a barcode approximately parallel to the Y axis, and a quantization circuit that binary encodes each line data read by each linear photosensor of this two-dimensional optical reading sensor. , an image data memory that stores each line data binary encoded by this quantization circuit, and all line data outputted from each line data at the same X coordinate position in each line data output from this image data memory. a Y-axis correction circuit that adds the added data to one corrected line data, and converts the line data output from the Y-axis correction circuit into code data corresponding to the bar code. A barcode reading device comprising a decoder circuit. (3) A plurality of linear photosensors each having a plurality of light receiving elements arranged linearly in the X direction of the reading window are arranged in the Y direction of the reading window, and each bar input from the reading window is A two-dimensional optical reading sensor that reads two-dimensional image information of a barcode approximately parallel to the Y axis, and a quantization circuit that binary encodes each line data read by each linear photosensor of this two-dimensional optical reading sensor. , an image data memory that stores each line data binary encoded by this quantization circuit, and each reference X coordinate position where the signal level first changes in each line data output from this image data memory as a reference. An x-axis phase correction circuit that shifts and corrects all the X-coordinate positions of each line data so that it matches the reference X-coordinate position of the line data, and each line data output from this X-axis phase correction circuit is converted into the bar code. A barcode reading device comprising a decoder circuit for converting into corresponding code data.