JP2006268699A - Code reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a code reader capable of improving the decoding speed of a data code. <P>SOLUTION: This code reader comprises an imaging means (imaging part 16) acquiring image data of the data code; a distance measuring means (distance measuring engine 152) measuring the distance between the data code and the imaging means; a determination means (control part 11) determining a thinning quantity of the image data based on the measured distance; a thinning means (data thinning part 153) thinning the acquired image data; and a decode means (decode part 17) decoding the thinned image data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a code reader for reading a data code.

Conventionally, various code readers for reading data codes such as bar codes and two-dimensional codes have been proposed and put into practical use. For example, a technique for improving the recognition rate by switching and using a plurality of illumination light sources in accordance with the conditions at the time of code reading has been proposed. There has also been proposed an apparatus for reducing the image data of the read two-dimensional code and cutting out the two-dimensional code from the reduced image data (see, for example, Patent Document 1).
JP 2000-259761 A

  However, in the above-described conventional code reading apparatus, since the light emission pattern is determined every time the code is read, there is a case where unnecessary light emission occurs when reading a standard code or the like. In addition, since the apparatus described in Patent Document 1 performs reading regardless of the distance to the code, even when the distance to the code is close and sufficient resolution can be obtained, the code at a distance is read. As a result, the same data amount is acquired, and there is a problem that the decoding speed is lowered.

  An object of the present invention is to provide a code reader capable of improving the decoding speed of a data code.

  According to the first aspect of the present invention, the imaging unit that acquires the image data of the data code, the ranging unit that measures the distance between the data code and the imaging unit, and the measured distance, Determining means for determining a thinning amount of image data; thinning means for thinning data from the acquired image data based on the determined thinning amount; and decoding means for decoding the thinned image data , Provided.

According to the present invention, the image data thinned out by the thinning amount corresponding to the distance from the imaging means to the data code is decoded. As a result, the amount of data related to decoding can be reduced, so that the decoding speed can be improved.
In addition, it is determined whether or not the data code can be read at the measured distance, and a notification is given when it is determined that the data code cannot be read. Therefore, the user can determine whether or not the data code can be read at the distance measurement stage. , There is no need to wait for the user with useless decoding.

<First Embodiment>
Hereinafter, a first embodiment of the code reading device of the present invention will be described. In the present embodiment, the data code is a concept including a bar code, a two-dimensional code, and the like.

  FIG. 1 shows a functional configuration of the code reading device 10. As shown in FIG. 1, the code reader 10 includes a control unit 11, a display unit 12, an operation unit 13, a storage unit 14, a CAMI / F 15, an imaging unit 16, a decoding unit 17, and the like. 18 is connected.

  The control unit 11 inputs and outputs data to and from each functional unit constituting the code reader 10, and performs CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory). ) Etc. More specifically, the control unit 11 reads a system program stored in the ROM and / or the storage unit 14, develops it in a work memory formed in the RAM, and controls each unit according to the system program. Further, the control unit 11 reads out various application programs such as various processing programs stored in the ROM and / or the storage unit 14, develops them in a work memory, executes various processes, and outputs the processing results to a work in the RAM. The data is stored in the memory and displayed on the display unit 12. Then, the processing result stored in the work memory is stored in the storage unit 14.

  When the control unit 11 receives distance data indicating the distance between the code reader 10 (imaging unit 16) and the data code, which is input from the ranging engine 152 described later, the control unit 11 receives the data code for each type of the data code. The associated distance information and resolution information are read out from the table of the storage unit 14, and based on the distance information and resolution information, the necessary resolution is calculated at the measured distance, and the thinning amount is determined. The data thinning unit 153 is controlled so that image data is thinned by the determined thinning amount. In the present embodiment, the necessary resolution is calculated based on the measured distance, but the necessary resolution value for each distance from the data code may be stored in the table in advance. Good.

Hereinafter, the thinning-out amount determined by the control unit 11 will be described with reference to FIG.
FIG. 2A is a diagram showing a part of a data code (two-dimensional code) to be read, and FIG. 2B is an enlarged view of a part shown in FIG. Here, the resolution of the imaging unit 16 to be described later is represented by each pixel (small area) indicated by B in FIG. In such a case, since there are three or more columns of pixels for one cell which is the minimum unit constituting the two-dimensional code, it is possible to decode the two-dimensional code even if image data is read every other column. is there. Since this can be applied to the vertical component and horizontal component of one cell, the amount of data to be read can be reduced by reading the horizontal component every other pixel and the vertical component every other line.

  Since the above-described thinning amount of the vertical direction component and the horizontal direction component needs to be reduced as the distance between the code reader 10 and the data code increases as shown in FIG. The vertical direction component and the horizontal direction component thinning-out amount corresponding to the distance input from are output to the data thinning unit 153 described later as the thinning-out amount. Hereinafter, the thinning amount of the vertical component is referred to as a line thinning amount and the thinning amount of the horizontal component is referred to as a clock thinning amount.

  Returning to FIG. 1, the display unit 12 includes an LCD (Liquid Crystal Display), an ELD (Electro Luminescence Display) panel, and the like, and performs screen display based on display data input from the control unit 11.

  The operation unit 13 includes a keyboard having a character input key, a numeric input key, and other keys associated with various functions, and outputs a pressing signal corresponding to a key pressed by a key operation by the user to the control unit 11. .

  The storage unit 14 is configured by a non-volatile memory such as a flash memory and the like, a system program corresponding to the code reader 10, various processing programs that can be executed on the system program, application programs, and data processed by these programs Record etc.

  The storage unit 14 stores in advance code size information indicating the size of the data code for each type of data code. In addition, a table in which distance information indicating a reference distance at the time of reading and resolution information indicating resolution necessary for reading at the distance is associated with the code size information is stored. Note that the code size information includes information on one cell, which is the minimum unit constituting the data code.

  The CAMI / F 15 includes an I / F unit 151, a ranging engine 152, a data thinning unit 153, an image processing unit 154, and the like. Hereinafter, each part of CAMI / F15 is demonstrated.

  The I / F unit 151 is an interface for connecting an imaging unit 16 to be described later, outputs image data input from the imaging unit 16 to be described later to the control unit 11, and controls the control unit 11 (ranging engine 152). ) Is output to the imaging unit 16.

  The ranging engine 152 adjusts the focus of the imaging unit 16 by driving and controlling an actuator (not shown) provided in the imaging unit 16 according to the control of the control unit 11. Further, the distance measurement engine 152 is based on the image data output from the imaging unit 16 when the focus value is changed, and the distance between the code reading device 10 (imaging unit 16) and the data code to be read. Measure. Specifically, the ranging engine 152 is based on the moving position at which the contrast value of the image data sequentially output from the imaging unit 16 becomes maximum when the actuator is moved one step (the focal point is moved away). The distance to the data code to be read is measured, and the measurement result is output to the control unit 11 as distance data.

  The data thinning unit 153 thins out a predetermined amount of data from the image data output from the imaging unit 16 based on the thinning amount input from the control unit 11, and the thinned image data is converted into an image processing unit. To 154.

Hereinafter, the data thinning unit 153 will be described with reference to FIGS. 4 and 5.
FIG. 4 is a block diagram illustrating the configuration of the data thinning unit 153, and FIG. 5 is a diagram illustrating an example of a timing chart of image data input to the data thinning unit 153.

  As shown in FIG. 4, the data thinning unit 153 includes a line register 1531, a clock register 1532, an HSYNC counter 1533, a clock counter 1534, a data thinning circuit 1535, and the like.

  The line register 1531 stores a line thinning amount that is a vertical component of the thinning amount input from the control unit 11. The clock register 1532 stores a clock thinning amount that is a horizontal component of the thinning amount input from the control unit 11.

  The HSYNC counter 1533 receives the VSYNC signal for measuring the vertical timing input to the HSYNC counter 1533, the HSYNC signal for measuring the horizontal timing, and the line thinning amount stored in the line register 1531. Based on this, a timing signal for thinning out the vertical component is output to the data thinning circuit 1535.

  Based on the clock signal input to the clock counter 1534 and the clock decimation amount stored in the clock register 1532, the clock counter 1534 outputs a timing signal for decimation in the horizontal direction to the data decimation circuit 1535.

  The data decimation circuit 1535 decimates a predetermined amount of data from the input image data (Data) based on the timing signals input from the HSYNC counter 1533 and the clock counter 1534, and the decimation image data (Data ') Is output. For example, when a timing signal for thinning out every other line with respect to the vertical component is input, the data in the timing chart shown in FIG. 5 is output every other line so that Line1, Line3,. become. In addition, when a timing signal for thinning out every other clock with respect to the horizontal component is input, PixelData (P0, P1,...) Included in each line shown in FIG. 5 becomes P0, P2, P4. Thus, it is output every other clock.

  In this embodiment, the vertical component and the horizontal component of the image data are thinned out. However, the present invention is not limited to this, and only the vertical component or the horizontal component may be thinned out.

  Returning to FIG. 1, the image processing unit 154 performs image processing such as gamma correction and white balance correction on the image data input from the data thinning unit 153, and then outputs the image data to the control unit 11. . The control unit 11 temporarily stores the image data input from the image processing unit 154 in the RAM or the storage unit 14.

  The imaging unit 16 includes an imaging element such as an optical lens, CMOS, and a CCD (Charge Coupled Diode), an actuator having a motor that moves the optical lens, and the like (all not shown), and is an object to be read. The data code is imaged, and the image data acquired by this imaging is output to the CAMI / F 15.

  The decoding unit 17 performs predetermined decoding processing on the image data stored in the RAM or the storage unit 14, thereby reading predetermined information represented in the thinned image data and outputting it to the control unit 11. The control unit 11 causes the display unit 12 to display the thinned image data input from the image processing unit 154 as a processing result, and stores the thinned image data in the storage unit 14.

  Hereinafter, the code reading process executed by the code reading device 10 will be described with reference to FIGS. 6 and 7. 6 and 7 show processing executed by software processing in cooperation with the control unit 11 of the code reading device 10 and a predetermined program stored in the ROM or the storage unit 14.

  First, as the process before reading the code, when the type of the data code to be read is selected via the operation unit 13 and this input signal is input (step S11), the code corresponding to the selected data code The size information is read from the storage unit 14 and stored in the RAM or the storage unit 14 so as to be set as a code condition for reading (step S12).

  Next, when the code reader 10 is moved to the vicinity of the data code to be read by the user, the process proceeds to a distance measuring process for measuring the distance from the code reader 10 to the data code (step S13).

Hereinafter, the distance measurement process (step S13) will be described with reference to FIG.
First, when the actuator is driven, the optical lens of the imaging unit 16 is moved to the closest position (motor position = 0) (step S131), and image data of a data code to be read is acquired (step S131). Step S132).

  Next, the contrast value of the image data acquired in step S132 is derived, and the contrast value is stored in the RAM or the storage unit 14 (step S133), and compared with the contrast value of the image data acquired last time. (Step S134).

  Here, when it is determined that the contrast value acquired last time is equal to or less than the contrast value acquired this time (step S134; No), the actuator is driven and the position of the motor is incremented by 1, whereby the optical lens is moved. One step is moved (step S135), and the process returns to step S132 again.

  On the other hand, if it is determined in step S134 that the previously acquired contrast value is greater than the currently acquired contrast value (step S134; Yes), the previous motor position is stored in the RAM or storage unit 14 as distance data. (Step S136), and the process proceeds to step S14.

  Returning to FIG. 6, the distance information and the resolution information under the present code condition are referred from the table of the storage unit 14, and the resolution necessary for reading at the distance measured in step S13 is derived (step S14). Subsequently, after determining the thinning amount based on the resolution derived in step S14 (step S15), the thinning amount is output to the data thinning unit 153 (step S16).

  Next, after the image data is acquired based on the input thinning amount (step S17), the acquired image data is decoded by the decoding unit 17 (step S18), and this process ends.

  As described above, according to the first embodiment, the image data thinned out by the thinning amount corresponding to the distance to the data code is decoded. As a result, the amount of data related to decoding can be reduced, so that the decoding speed can be improved.

<Second Embodiment>
Next, a second embodiment of the code reading device 10 will be described. For simplification of description, the same components as those of the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only characteristic portions of the second embodiment will be described.

With reference to FIG. 1, the control part 11 and the memory | storage part 14 in the 2nd embodiment are demonstrated.
The storage unit 14 stores distance limit information and resolution information in association with the code size information stored for each data code type, and stores resolution limit value information indicating a limit value of resolution that can be read. The associated table is stored.

  When the control unit 11 receives distance data indicating the distance between the code reader 10 (imaging unit 16) and the data code input from the ranging engine 152, the distance information associated with the type of the data code. And the resolution information are read from the storage unit 14, and based on the distance information and the resolution information, a necessary resolution is calculated at the measured distance, and the calculated value is a limit indicated by the resolution limit value information. It is determined whether it is within the value.

  Hereinafter, the code reading process in the second embodiment will be described with reference to FIG. FIG. 8 shows processing executed by software processing in cooperation with the control unit 11 of the code reading device 10 and a predetermined program stored in the ROM or the storage unit 14.

  First, as the process before reading the code, when the type of the data code to be read is selected via the operation unit 13 and this input signal is input (step S21), the code corresponding to the selected data code The size information is read from the storage unit 14 and stored in the RAM or the storage unit 14 so as to be set as a code condition for reading (step S22).

  Next, when the code reader 10 is moved to the vicinity of the data code to be read by the user, the process proceeds to a distance measuring process for measuring the distance from the code reader 10 to the data code (step S23). The distance measurement process (step S23) is the same as the distance measurement process of FIG. 7 described in the first embodiment, and a description thereof will be omitted.

  Subsequently, the distance information and the resolution information under the present code condition are referred from the table of the storage unit 14, and the resolution necessary for reading at the distance measured in step S13 is derived (step S24). Further, resolution limit value information under this code condition is referred to from the table of the storage unit 14, and it is determined whether or not the resolution value derived in step S24 is within the limit value indicated by the resolution limit value information. Determination is made (step S25).

  Here, when it is determined that the resolution value exceeds the limit value (step S25; No), a display indicating that the data code cannot be read is displayed on the display unit 12 (step S26). The process ends.

  On the other hand, when it is determined in step S25 that the resolution value is within the limit value (step S25; Yes), after the thinning amount is determined based on the resolution derived in step S24 (step S27), This thinning amount is output to the data thinning unit 153 (step S28).

  Next, after the image data is acquired based on the input thinning amount (step S29), the acquired image data is decoded by the decoding unit 17 (step S30), and this process ends.

As described above, according to the second embodiment, the image data thinned out with the thinning amount corresponding to the distance to the data code is decoded. As a result, the amount of data related to decoding can be reduced, so that the decoding speed can be improved.
In addition, it is determined whether or not the data code can be read at the measured distance, and the user is notified when it is determined that the data cannot be read. Therefore, the user can determine whether or not the barcode can be read at the distance measurement stage. , There is no need to wait for the user with useless decoding.

<Modification>
The application of the present invention is not limited to the above-described example, and can be changed as appropriate without departing from the spirit of the present invention.

  For example, in the first embodiment, when thinning out image data, as shown in FIG. 2, effective pixels after thinning are arranged squarely in the vertical direction component and the horizontal direction component. However, the present invention is not limited to this, and it may be arranged in a rhombic shape as shown in FIG. This is particularly effective when the data code to be imaged is tilted.

  The description in the present embodiment shows an example of the code reading apparatus according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the code reading device 10 in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

It is a block diagram which shows typically the functional structure of a code reader. It is a figure which shows the relationship between a data code and resolution, Comprising: (a) It is a figure which shows a part of data code, (b) It is the figure which expanded the part shown in FIG. 2 (a). It is a figure which shows the relationship between a code reader and a data code. It is a block diagram which shows typically the functional structure of a data thinning part. It is a figure which shows an example of the timing chart of the image data input into a data thinning part. It is a flowchart which shows the procedure of the code reading process in 1st Embodiment. It is a flowchart which shows the procedure of a ranging process. It is a flowchart which shows the procedure of the code reading process in 2nd Embodiment. It is a figure which shows the relationship between a data code and resolution | decomposability.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Code reader 11 Control part 12 Display part 13 Operation part 14 Storage part 15 CAMI / F
151 I / F unit 152 Ranging engine 153 Data thinning unit 154 Image processing unit 1531 Line register 1532 Clock register 1533 HSYNC counter 1534 Clock counter 1535 Data thinning circuit 16 Imaging unit 17 Decoding unit 18 Bus

Claims (6)

Imaging means for obtaining image data of a data code;
Distance measuring means for measuring a distance between the data code and the imaging means;
Determining means for determining a thinning amount of the image data based on the measured distance;
Thinning means for thinning data from the acquired image data based on the determined thinning amount;
Decoding means for decoding the thinned image data;
A code reading device comprising: For each type of the data code, further comprising storage means for storing in advance code size information indicating the code size of the data code,
2. The code reader according to claim 1, wherein the determining unit determines the thinning amount based on code size information corresponding to a data code of the acquired image data and the measured distance. . The storage means stores in advance a table in which the distance and the resolution of the imaging means are associated with each data code type,
The code reading apparatus according to claim 1, wherein the determining unit determines the thinning amount based on a distance and a resolution stored in the table. The storage means stores in advance a resolution limit value at which the data code can be read for each type of the data code,
Determining means for determining whether the data code can be read at the measured distance based on the stored resolution limit;
A notification means for performing a notification when the determination means determines that reading is impossible;
The code reader according to claim 3, further comprising: A focus adjusting means for adjusting a focal length of the imaging means;
2. The code reading device according to claim 1, wherein the distance measuring unit measures a distance to the data code based on a contrast value of the image data acquired at the adjusted focal length.   2. The code reading apparatus according to claim 1, wherein the thinning unit thins data in a vertical component direction and / or a horizontal component direction of the image data.

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