JP4466522B2 - Optical information reader - Google Patents

Description

  The present invention relates to a rolling shutter optical information reader, and more particularly to an optical information reader capable of correcting camera shake.

  Conventionally, optical information readers such as barcode readers and two-dimensional code readers read illumination light from LEDs and lasers in order to read information codes (barcodes and two-dimensional codes) printed on paper and products. By irradiating the information code from the mouth and receiving the reflected light by a light receiving sensor or the like in the reading mouth, the optical information by the information code can be read. In such an optical information reading apparatus, the reading operation is usually carried out while keeping the distance from the reading port to the information code at a relatively short distance of about 5 to 10 cm.

  However, in recent years, there are many requests that the information code be read from a relatively distant position such as several tens of centimeters or about 1 to 2 meters from the reading port. On the other hand, in the conventional optical information reader, since information codes relatively close to each other are exclusively read, when an attempt is made to read such a remote information code, an image of reflected light incident on the light receiving sensor is processed. May be shaken by a person's camera shake (hereinafter referred to as "image shake"). For this reason, it has been pointed out that the conventional optical information reader is difficult to read a remote information code.

Therefore, in order to solve such a problem of camera shake (image blur), for example, an “optical system” disclosed in the following Patent Document 1 and an “image blur correcting apparatus” disclosed in the following Patent Document 2 are used. An optical information reader is conceivable. For example, in the disclosed technique of Patent Document 1, an image forming optical system is configured by a plurality of lens groups such as a first lens group, a second lens group, and a third lens group, and camera shake correction that configures a part of the second lens group. By configuring the group to be movable in the direction perpendicular to the optical axis, camera shake correction is possible. In the technique disclosed in Patent Document 2, the image blur correction lens group held in the moving frame is configured to be movable in a direction orthogonal to the optical axis via the moving frame by a plurality of electromagnetic actuators, thereby correcting image blur correction. It is possible. Therefore, it is considered that the problem of camera shake (image blur) can be solved by applying these disclosed techniques to an optical information reader.
JP-A-9-236742 JP 2003-57707 A

  However, according to the techniques disclosed in Patent Document 1 and Patent Document 2, in any case, a drive device or drive mechanism such as an electromagnetic actuator that can drive a lens or the like, and a control device that controls them are required. Become. In addition, an acceleration sensor (G sensor) is also required to detect the direction of camera shake by the operator. Furthermore, in order to mount these driving devices, control devices, sensors, etc., a considerable mounting space is required in the device.

  Therefore, when such disclosed techniques according to Patent Documents 1 and 2 are applied to the optical information reading apparatus described above, even if it is possible to prevent camera shake and image blur, (1) newly mechanically, Since electrical components must be added, the number of parts increases, leading to an increase in product cost and failure rate. (2) A space for accommodating these mechanisms and control circuits is required. For this reason, a technical problem that an increase in the size of the apparatus cannot be avoided may occur.

  The present invention has been made to solve the above-described problems, and its object is to correct camera shake without causing an increase in product cost, an increase in failure rate, an increase in size of the apparatus, and the like. An optical information reader is provided.

  In order to achieve the above object, in the optical information reading device according to claim 1, an illumination light source capable of emitting illumination light that can be emitted to an information code, and the information code is emitted from the illumination light source. The information code is irradiated with a light receiving sensor that forms a light receiving surface by two-dimensionally arranging light receiving elements capable of receiving reflected light reflected by the light and marker light that can indicate a predetermined position within the illumination light irradiation range. Marker reflected light reflected and reflected by the marker light source having a column direction component of the two-dimensional array of the light receiving elements, a code image of the information code by the reflected light, and a marker image by the marker reflected light An image forming optical system capable of forming an image on the light receiving surface of the light receiving sensor, and an image information accumulating means having an information processing function, wherein the code image output from the light receiving sensor and the mar Image information storage means capable of acquiring and storing image information of an image by a rolling shutter method by the information processing function, and determining the marker image from image information of the code image and the marker image stored in the image information storage means Based on the marker image acquisition means that can be acquired and the marker image acquired by the marker image acquisition means, the shift amount and the shift direction in the row direction of the two-dimensional array of the marker image with respect to the predetermined position are calculated. An image for returning the code image based on the image information accumulated in the image information accumulating means to the predetermined position based on the possible deviation amount calculating means and the deviation amount and the deviation direction calculated by the deviation amount calculating means. A correction unit, and the image information storage unit includes the marker image acquisition unit, the deviation amount calculation unit, and the image correction unit. And technical features that are implemented by the serial information processing function.

  The “information code” is not limited to a one-dimensional code (EAN / UPC, interleaved 2 of 5, coder bar, code 39/128, standard 2 of 5, RSS, etc.), and a two-dimensional code (QR code, PDF417). , Data matrix, maxi code, RSS composite, etc.).

  Further, in the optical information reading device according to claim 2, in the optical information reading device according to claim 1, the deviation amount calculating means can detect a deviation portion of a row direction component of the marker image. A misalignment portion detection means, and a misalignment range determination means capable of determining the misalignment range occupied by the misalignment portion detected by the misalignment portion detection means, the misalignment range determined by the misalignment range determination means and other It is a technical feature that the shift amount and the shift direction are calculated for a peripheral range.

  Furthermore, in the optical information reading device according to claim 3, wherein the optical information reading device according to claim 1 or 2, the deviation amount calculating means includes the rows of the two-dimensional array, A technical feature is that a plurality of lines are skipped and a deviation amount is calculated for a predetermined two or more lines, and a deviation amount of the plurality of skipped lines is calculated based on the deviation amounts of the two or more lines.

  Further, in the optical information reading device according to claim 4, wherein the marker image acquisition means is a component of the reflected light, in the optical information reading device according to any one of claims 1 to 3. The marker image is discriminated from the code image stored in the image information storage means from the difference between the marker reflected light component and the marker reflected light component.

  Furthermore, in the optical information reading device according to claim 5, wherein the marker image acquisition means is a luminance of the reflected light, according to any one of claims 1 to 3. The marker image is discriminated from the code image stored in the image information storage means based on the difference between the brightness of the marker reflected light and the marker.

  Further, in the optical information reading device according to claim 6, in the optical information reading device according to any one of claims 1 to 5, the marker light is substantially cross-shaped on the information code. It is a technical feature that it is irradiated so as to form a shape.

  According to the first aspect of the present invention, the image information storage means captures and stores the image information of the code image and marker image output from the light receiving sensor by the rolling shutter system, and the code image and marker stored in the image information storage means. The marker image is discriminated from the image information of the image by the marker image acquisition means and acquired. Then, based on the marker image acquired by the marker image acquisition means, the amount of deviation in the row direction and the direction of deviation of the marker image with respect to a predetermined position are calculated by the amount of deviation calculation means, and calculated by the amount of deviation calculation means. The code image based on the image information accumulated in the image information accumulating means is returned to a predetermined position by the image correcting means based on the deviation amount and the deviation direction.

  Thereby, for example, even if image blurring occurs in the code image based on the image information stored in the image information storage unit due to the camera shake of the operator, the image is based on the shift amount and the shift direction calculated by the shift amount calculation unit. Since it is possible to return to a predetermined position by the correcting means, it is possible to prevent image blurring. The marker image acquisition unit, the deviation amount calculation unit, and the image correction unit are realized by the information processing function of the image information storage unit, that is, the function provided by the information processing device (CPU, semiconductor memory, etc.). Image blurring can be prevented by using the information processing function of the existing image information storage means without adding mechanical and electrical components as in the technologies disclosed in Patent Documents 1 and 2 described above. Therefore, camera shake can be corrected without causing an increase in product cost, an increase in failure rate, and an increase in the size of the apparatus.

  In the invention of claim 2, the deviation amount calculation means includes a deviation portion detection means and a deviation range determination means, and calculates a deviation amount and a deviation direction for the deviation range determined by the deviation range determination means and its outer peripheral range. . As a result, the portion in which the row direction component of the marker image is not displaced is not detected by the displacement portion detecting means, and thus is not included in the displacement range and is not subject to calculation of the displacement amount and the displacement direction. For this reason, since the deviation amount calculation means calculates the deviation amount and the deviation direction except for such a portion without deviation, the deviation amount and the deviation direction are set for all the image information accumulated in the image information accumulation means. Compared with the case of calculation, the speed of the calculation process can be improved, and the processing load can be reduced. Accordingly, it is possible to increase the speed of camera shake correction.

  In the invention of claim 3, the deviation amount calculation means calculates a deviation amount for a predetermined two or more rows by skipping a plurality of rows among the rows constituting the two-dimensional array, and based on the deviation amounts of these two or more rows. The amount of misalignment of the skipped lines is calculated. As a result, for the plurality of skipped lines, the shift amount is calculated indirectly based on the shift amount obtained for two or more predetermined lines without directly calculating the shift amount. The speed of the calculation process can be improved and the load on the information processing function can be reduced as compared with the case where the shift amount and the shift direction are calculated for all the rows of image information stored in. Accordingly, it is possible to increase the speed of camera shake correction.

  In the invention of claim 4, since the marker image acquisition means discriminates the marker image from the code image stored in the image information storage means based on the difference between the reflected light component and the marker reflected light component, it is possible to emit irradiation light. By setting the emission color of a simple illumination light source and the emission color of a marker light source capable of emitting marker light to be different, the marker image can be easily distinguished from the code image.

  In the invention of claim 5, since the marker image acquisition means discriminates the marker image from the code image stored in the image information storage means based on the difference between the brightness of the reflected light and the brightness of the marker reflected light, the marker light can be emitted. By setting the emission intensity of the illumination light source different from the emission intensity of the marker light source capable of emitting marker light, the marker image can be easily distinguished from the code image.

  In the invention of claim 6, the marker light is irradiated so as to form a substantially cross shape on the information code. This makes the cross-shaped vertical bar a component in the column direction of the two-dimensional array of light receiving elements, while accurately identifying the information code to be read using the intersection of the cross-shaped vertical bar and horizontal bar as a mark. Can be aimed at.

  Hereinafter, an embodiment in which an optical information reader of the present invention is applied to a two-dimensional code reader will be described with reference to the drawings. First, a configuration outline of the two-dimensional code reader 10 according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 1, a two-dimensional code reader 10 is integrally formed with a housing body 11 having a rounded, thin, substantially rectangular box shape, and a lower surface of the housing body 11 substantially near the rear end. And a gun-type housing comprising the grip portion 12. The grip portion 12 is set to have an outer diameter that allows an operator to hold the grip portion 12 with one hand, and an illumination light Lf and a marker light Mf, which will be described later, are in contact with the index finger of the operator holding the grip portion 12. A trigger switch 14 is provided for instructing the emission of light.

  A circuit unit 20 (described later) is accommodated in the housing main body 11, and illumination light Lf emitted from the circuit unit 20 can be emitted from the tip of the housing main body 11, or reflected light Lr. A reading port 11a is formed to enable the incidence of. 1 shows the printed wiring boards 15 and 16 constituting the circuit unit 20, the light receiving sensor 23, the marker light source 25, the laser diode 25a, the imaging lens 27, and the like mounted on the printed wiring board 16. ing.

  As shown in FIG. 2, the circuit unit 20 mainly includes an optical system such as an illumination light source 21, a light receiving sensor 23, and an imaging lens 27, a memory 35, a control circuit 40, an operation switch 42, a liquid crystal display 46, and the like. A microcomputer (hereinafter referred to as “microcomputer”) system and a power supply system such as a power switch 41 and a battery 49 are mounted on the printed wiring boards 15 and 16 or housed in the housing body 11. .

  The optical system includes an illumination light source 21, a light receiving sensor 23, a marker light source 25, an imaging lens 27, and the like. The illumination light source 21 functions as an illumination light source capable of emitting illumination light Lf, and includes, for example, a red LED and a diffusion lens, a condensing lens, and the like provided on the emission side of the LED. In the present embodiment, illumination light sources 21 are provided on both sides of the light receiving sensor 23, and the illumination light Lf can be irradiated toward the reading object R through the reading port 11 a of the housing body 11. . The reading object R is affixed with a two-dimensional code Q as an information code.

  The light receiving sensor 23 is configured to receive the reflected light Lr irradiated and reflected on the reading object R or the two-dimensional code Q. For example, the light receiving element 22 which is a solid-state imaging device such as a C-MOS or CCD. This is equivalent to an area sensor in which two rows are arranged in m rows and n columns in the order of 1 million. The light receiving surface 23a of the light receiving sensor 23 is positioned so as to be visible from the outside of the housing body 11 through the reading port 11a. The light receiving sensor 23 receives incident light incident through the imaging lens 27 as the light receiving surface 23a. It is mounted on the printed wiring board 16 so that it can receive light.

  The marker light source 25 functions as a marker light source capable of emitting marker light Mf that can indicate a predetermined position within the irradiable range of the illumination light Lf. For example, the marker light source 25 is provided on the laser diode 25a and the emission side of the laser diode 25a. It comprises a diffusing lens, a condensing lens, a slit plate capable of forming a guide pattern for the marker light Mf, an imaging lens, a diaphragm plate, and the like (see FIG. 1). As shown in FIG. 3A, in the present embodiment, the guide pattern of the marker light Mf is four L-shaped field guides indicating the four corners of the imaging field of view (predetermined positions within the irradiable range) of the light receiving sensor 23. Ma and a cross-shaped center guide Mb indicating the approximate center of the imaging field of view are configured. Thus, when the marker light Mf is irradiated toward the reading object R, four field guides Ma and a center guide Mb indicating the center thereof are projected on the surface of the reading object R. The two-dimensional code Q serving as a reading target can be positioned within the range surrounded by the visual field guide Ma, that is, within the imaging visual field (see FIG. 3A). In the present embodiment, since the center guide Mb indicating the center of the four field guides Ma is formed in a cross shape, the object to be read is used with the intersection of the cross-shaped vertical bar portion Pmc and the horizontal bar portion Pmr as a mark. It is possible to accurately aim at the two-dimensional code Q of R.

  The imaging lens 27 functions as an imaging optical system capable of condensing incident light incident from the outside through the reading port 11a and forming an image on the light receiving surface 23a of the light receiving sensor 23. It is comprised by the cylinder and the some condensing lens accommodated in this barrel. In the present embodiment, the illumination light Lf emitted from the illumination light source 21 is reflected by the two-dimensional code Q and incident on the reading port 11a, or the marker light Mf emitted from the marker light source 25 is read object R. By condensing the marker reflected light Mr that is reflected and incident on the reading port 11a, the code image Pc and the marker image Pm can be formed on the light receiving surface 23a of the light receiving sensor 23. Thereby, for example, when the marker image Pm of the center guide Mb is incident on the imaging lens 27, a cross shape is imaged on the light receiving surface 23a composed of a plurality of light receiving elements 22 arranged in two dimensions in m rows and n columns. (See FIG. 3B). The vertical bar portion Pmc constituting the cross shape corresponds to a component in the column direction of the two-dimensional array, and the horizontal bar portion Pmr constituting the cross shape corresponds to a component in the row direction of the two-dimensional array (see FIG. 3 (B)).

  Next, returning to FIG. 2, the outline of the configuration of the microcomputer system will be described. The microcomputer system includes an amplification circuit 31, an A / D conversion circuit 33, a memory 35, an address generation circuit 36, a synchronization signal generation circuit 38, a control circuit 40, an operation switch 42, an LED 43, a buzzer 44, a liquid crystal display 46, and a communication interface 48. Etc. As the name suggests, this microcomputer system is composed mainly of a control circuit 40 and a memory 35 that can function as a microcomputer (information processing apparatus). The code image Pc and the marker image Pm captured by the optical system described above. The image signal such as can be processed by hardware and software. The control circuit 40 also performs control related to the entire system of the two-dimensional code reader 10.

  An image signal (analog signal) output from the light receiving sensor 23 of the optical system is input to the amplification circuit 31 and amplified by a predetermined gain, and then input to the A / D conversion circuit 33. Converted into a digital signal. When the digitized image signal, that is, image data (image information) is input to the memory 35, it is accumulated in a predetermined code image / marker image image information storage area 35a. The synchronization signal generation circuit 38 is configured to generate a synchronization signal for the light receiving sensor 23 and the address generation circuit 36. The address generation circuit 36 is based on the synchronization signal supplied from the synchronization signal generation circuit 38. Thus, the storage address of the image data stored in the memory 35 can be generated.

  In the present embodiment, the image signal output from the light receiving sensor 23 is not exposed to all the light receiving elements 22, that is, all pixels (m rows and n columns) at a time and receives all of them (global shutter method). Since a method (rolling shutter method) in which one row of the two-dimensional array constituting the surface 23a is sequentially exposed from the top and sequentially fetched for each row is adopted, the code image / marker image image information storage of the memory 35 is stored. In the region 35a, each of the two-dimensional arrays constituting the light receiving surface 23a is arranged in the order of 1 row m column → 2 row m column → 3 row m column →... → (n−1) row m column → n row m column. Image data is accumulated.

  The memory 35 is a semiconductor memory device, and corresponds to, for example, a RAM (DRAM, SRAM, etc.) or a ROM (EPROM, EEPROM, etc.). In addition to the above-described code image / marker image image information storage area 35a, the RAM 35 in the memory 35 is used by the marker image image information storage area 35b and the control circuit 40 for each processing such as arithmetic operation and logical operation. The working area to be secured is also configured to be secured. In addition, the ROM stores a predetermined program capable of executing an image storage process 40a, a marker image acquisition process 40b, a shift amount calculation process 40c, an image correction process 40d, and the like, which will be described later, an illumination light source 21, a light receiving sensor 23, a marker light source 25, and the like. A system program or the like that can control each piece of hardware is stored in advance.

  The control circuit 40 is a microcomputer capable of controlling the entire two-dimensional code reader 10 and includes a CPU, a system bus, an input / output interface, and the like. The control circuit 40 can constitute an information processing apparatus together with the memory 35 and has an information processing function. The control circuit 40 is configured to be connectable to various input / output devices (peripheral devices) via a built-in input / output interface. In the present embodiment, the power switch 41, the operation switch 42, the LED 43, A buzzer 44, a liquid crystal display 46, a communication interface 48, and the like are connected. Thereby, for example, monitoring and management of the power switch 41 and the operation switch 42, turning on / off the LED 43 functioning as an indicator, turning on / off the buzzer 44 capable of generating a beep sound and an alarm sound, and further reading the two-dimensional The screen control of the liquid crystal display 46 capable of displaying the code content by the code Q, the communication control of the communication interface 48 enabling serial communication with an external device, and the like are enabled. The operation switch 42 includes the trigger switch 14 described above.

  The power supply system includes a power switch 41, a battery 49, and the like. When the power switch 41 managed by the control circuit 40 is turned on and off, the conduction of the drive voltage supplied from the battery 49 to each device and each circuit described above is established. Or shut off is controlled. The battery 49 is a secondary battery that can generate a predetermined DC voltage, and corresponds to, for example, a lithium ion battery.

  By configuring the two-dimensional code reader 10 in this way, for example, when the power switch 41 is turned on and a predetermined self-diagnosis process or the like is normally completed and the two-dimensional code Q can be read, the control circuit 40 Outputs a light emission signal to the marker light source 25 at a predetermined period based on the synchronization signal. As a result, the marker light source 25 that has received the light emission signal intermittently emits the laser diode 25a to emit the marker light Mf, so that the operator points the reading port 11a toward the reading object R, and thus the reading port 11a. By irradiating the reading object R with marker light Mf emitted from the visual field guide Ma, the visual field guide Ma and the central guide Mb can be visually recognized.

  Then, after the operator positions the two-dimensional code Q serving as the reading target in the imaging field surrounded by the four field guides Ma, when the trigger switch 14 is pressed and turned on, the control circuit 40 uses the synchronization signal as a reference. A light emission signal is output to the illumination light source 21. Accordingly, the illumination light source 21 that has received the light emission signal causes the LED to emit light and irradiate the illumination light Lf. Therefore, the illumination light Lf is applied to the two-dimensional code Q located in the imaging field of view and the reflected light Lr. Enters the imaging lens 27 through the reading port 11a. In addition, the marker light Mf generated by the marker light Mf applied to the reading object R and the two-dimensional code Q also enters the imaging lens 27 through the reading port 11a. Therefore, the code image Pc and the marker image Pm are formed on the light receiving surface 23 a of the light receiving sensor 23 by the imaging lens 27, and the respective images can be exposed to the light receiving element 22 of the light receiving sensor 23.

  For example, in the case of the center guide Mb of the marker image Pm, when there is no camera shake by the operator and there is no image blur, the cross shape at the time of irradiation is almost as it is as shown in FIG. A portion Pmc and a horizontal bar portion Pmr) are imaged on the light receiving surface 23a. On the other hand, when reading the two-dimensional code Q remotely from the reading port 11a of the two-dimensional code reader 10 held by the worker, for example, it accompanies the movement of a finger that tries to turn on by pressing the trigger switch 14. Since it is easily affected by camera shake, image blur may occur in the marker image Pm formed on the light receiving surface 23a as described later. In such a case, since the same image blur occurs in the code image Pc, there is a high possibility of an error in the decoding process of the code.

  Therefore, in the two-dimensional code reader 10 according to the present embodiment, image blur due to camera shake of an operator, which is likely to occur when reading such a remote two-dimensional code Q, is corrected by a camera shake correction process described below. It is possible. The light receiving surface 23a shown in FIG. 3 (B) takes out a part of m rows and n columns for convenience, and has an array of 9 rows and 14 columns (first row, second row, third row, fourth row, second row). 5th row, 6th, 7th, 8th row, 9th row (hereinafter these are collectively referred to as "1st row to 9th row") / B column, B column, C column, D column, E column, F A row, a row, a row, a row, a row, a row, a row, a row, and a row (hereinafter, these are collectively referred to as “the first row to the first row”) are represented on the drawing.

  Next, camera shake correction processing by the two-dimensional code reader 10 will be described with reference to FIGS. First, an overview of the camera shake correction processing according to the present embodiment will be described with reference to FIG. This camera shake correction process is executed by the control circuit 40 and the memory 35 described above. FIG. 4 shows an image accumulation process 40a, a marker image acquisition process 40b, and a deviation amount calculation process that constitute the camera shake correction process. The block diagram which shows the relationship between 40c and the image correction process 40d is shown.

  As shown in FIG. 4, in the camera shake correction process, the image data Pc and the marker image Pm output from the light receiving sensor 23 are captured by the image accumulation process 40a by the rolling shutter method, and the code image / marker image image information is stored. Accumulate in area 35a. Next, the marker image acquisition process 40b determines and acquires the marker image Pm from the image data of the code image Pc and the marker image Pm accumulated in the code image / marker image image information storage area 35a. This marker image Pm is stored in the marker image image information storage area 35b.

  Then, the shift amount calculation processing 40c calculates the shift amount and the shift direction in the row direction of the two-dimensional array of the marker image Pm with respect to the predetermined position based on the marker image Pm stored in the marker image image information storage area 35b. The code image Pc based on the image data stored in the code image / marker image information storage area 35a is returned to a predetermined position by the image correction process 40d based on the shift amount and the shift direction calculated by the shift amount calculation process 40c.

  Thus, for example, even if an image blur occurs in the code image Pc due to the image data accumulated in the code image / marker image image information storage area 35a due to the camera shake of the operator, the shift calculated by the shift amount calculation processing 40c. Since the code image Pc based on the image data stored in the code image / marker image image information storage area 35a can be returned to a predetermined position by the image correction processing 40d based on the amount and the deviation direction, image blurring can be prevented. Can do.

  Next, the camera shake correction process outlined based on FIG. 4 will be specifically described with reference to FIGS. 5 and 6. FIG. 5 is a flowchart showing the flow of the camera shake correction processing. FIG. 6 shows a marker image Pm formed on the light receiving surface 23a of the light receiving sensor 23 as a marker image on the memory 35. An image diagram developed in the information storage area 35b is shown.

  As shown in FIG. 5, the camera shake correction process starts from the illumination light irradiation process in step S <b> 101 with the trigger switch 14 being turned on as a trigger. In this process, the illumination light Lf is emitted by the illumination light source 21 described above, and the control circuit 40 outputs a light emission signal to the illumination light source 21 based on the synchronization signal. Light is emitted to irradiate illumination light Lf. Note that, as described above, for example, when the power switch 41 of the two-dimensional code reader 10 is turned on, the marker light Mf emitted from the marker light source 25 is repeatedly turned on / off repeatedly and emitted from the reading port 11a. Has been.

  When the reading object R is irradiated with the illumination light Lf, an image reading process is performed in step S103. This process is performed when the reflected light Lr or the marker reflected light Mr reflected by the reading object R after being irradiated with the illumination light Lf or the marker light Mf is incident on the light receiving sensor 23 through the imaging lens 27. Therefore, the control circuit 40 outputs an exposure signal to the light receiving sensor 23 based on the synchronization signal.

  In the case of the present embodiment, since the rolling shutter system is adopted, the light receiving sensor 23 that has received the exposure signal is sequentially turned by the internal counter from the top row of the light receiving surface 23a to the bottom row one by one from the bottom row. To expose. More specifically, as shown in FIG. 6A, among the m rows and n columns, the light receiving sensor 23 is exposed by collecting the first column to the first column for the first row by the first exposure signal. The second exposure signal collects the second row of the first column to the first column, the next exposure signal collects the third row of the first column to the second column, and so on. When the exposure of the ninth row at the bottom row is completed, the internal counter is reset and the exposure is started from the top row again.

  In the subsequent step S105, an image information accumulation process is performed. This processing corresponds to the above-described image accumulation processing 40a, and the image signal sequentially output for each row from the light receiving sensor 23 is converted into digital data, that is, the code image Pc and the marker through the A / D conversion circuit 33. The image data is converted into image data of the image Pm, is captured by the rolling shutter method, and is stored in the code image / marker image image information storage area 35 a of the memory 35. Since the light receiving sensor 23 sequentially outputs the first row, the second row,... For each row, image data is stored in the code image / marker image image information storage area 35a in accordance with the rolling shutter system.

  In the next step S107, marker image acquisition processing is performed. This process corresponds to the marker image acquisition process 40b described above. The marker image Pm is obtained from the image data of the code image Pc and the marker image Pm accumulated in the code image / marker image image information storage area 35a in step S105. It is determined and acquired and stored in the marker image image information storage area 35b. That is, since both the code image Pc and the marker image Pm are stored and stored in the code image / marker image image information storage area 35a, a process of determining and acquiring the marker image Pm from these is performed.

  As the discrimination processing in step S107, for example, the component of the illumination light Lf that can form the code image Pc by setting the emission color of the illumination light source 21 to red and the emission color of the marker light source 25 to blue. From the difference from the component of the marker reflected light Mr that can form the marker image Pm, the filtering process is performed based on the brightness difference of the color by the gray scale. As a result, images having different colors can be selectively extracted depending on the filter characteristics, so that the marker image Pm can be easily determined from the code image Pc stored in the code image / marker image image information storage area 35a. .

  Moreover, as this discrimination | determination process, the brightness | luminance of the illumination light Lf which can image the code | cord | chord image Pc is set by setting the luminescence intensity of the illumination light source 21 strong, and setting the luminescence intensity weaker than this to the marker light source 25, for example. From the difference between the brightness of the marker reflected light Mr that can form the marker image Pm, the filtering process is performed depending on the strength of the signal level. As a result, images having different signal intensities can be selectively extracted depending on the filter characteristics. Therefore, the marker image Pm can be easily obtained from the code image Pc accumulated in the code image / marker image image information storage area 35a even by such a method. Can be determined.

  The marker image Pm acquired in step S107 is taken out and stored in the marker image image information storage area 35b, for example, as shown in FIG. This region is defined by a two-dimensional array of m rows and n columns, and the above-described light receiving surface 23a of the light receiving sensor 23 can be conceptualized in the same manner. Therefore, in FIG. 6 (A) and FIG. 6 (B), reference numeral 23a of the light receiving surface is given in parentheses. In these figures, among the marker images Pm, an array in which image data “1” corresponding to a part of the center guide Mb is stored is indicated by ■ (black square), and other image data “0” is stored. The stored array is indicated by □ (white square) (same in FIGS. 7 and 8).

  In the example shown in FIG. 6A, in the marker image image information storage area 35b (or the light receiving surface 23a), the image data (first row, second row, third row) of the reference position of the marker image Pm. Row 1 column, 4th row column, 5th row a column to 5th row column, 6th row column, 7th row column, 8th row column, 8th row column, 9th row column) "1" In addition, the second row, the fourth row, the fourth row, the sixth row, the sixth row, the sixth row, the sixth row, the seventh row, the seventh row, Column, seventh row column, eighth row column, eighth row column, eighth row column, eighth row column, ninth row column, ninth row column, ninth row column, “1” is also set for image data corresponding to pixels in the ninth row. In the present embodiment, the reference position of the marker image Pm is set with reference to “1” in the first row to be exposed first because the image data is taken in by the rolling shutter method.

  This is due to pixel components due to image blurring peculiar to the rolling shutter system due to the occurrence of camera shake on the left side of the paper surface, and these are calculated as the shift amount by the shift amount calculation processing in the next step S109. . That is, in step S109, based on the reference position of the marker image Pm, the shift amount and the shift direction in the row direction of the two-dimensional array of the marker image Pm stored in the marker image image information storage area 35b are calculated. This process corresponds to the above-described deviation amount calculation process 40c.

  In this step S109, the shift amount and the shift direction of the subsequent rows are calculated based on “1” in the first row and the first column set as the reference position of the marker image Pm. In the example shown in FIG. 6 (A), for example, in the second row, “1” in the first column is also “1” in the next right column, so that it is shifted by one pixel in the “column direction”. I understand that. Therefore, since there is a shift amount of one pixel on the right side (+ side) with respect to the page, the second row is calculated as a shift amount “+1”.

  Similarly, in the fourth row, “1” in the first column is “1” in the right adjacent column, and the right adjacent column is also “1”. The amount of deviation is calculated as “+2”. Similarly, the sixth line is calculated as a shift amount “+3”, the seventh line is calculated as a shift amount “+3”, the eighth line is calculated as a shift amount “+4”, and the ninth line is calculated as a shift amount “+4”. In the third row, since there is no “1” in the right column of the G column, the shift amount is “+0”. For the fifth row, since “1” is entered in all columns due to the horizontal bar portion Pmr constituting the marker image Pm (center guide Mb), the shift amount is calculated for the fifth row. It is not possible.

  Such processing is also performed on the left column adjacent to each row (second row to ninth row), and when the shift amount is calculated, the shift amount is set to “−1” or the like. In the rolling shutter method, it is difficult to think of image blurring in both the left and right directions, but there is a possibility of image blurring in either the left direction (row direction) or the right direction (h direction). Calculate the amount and determine the displacement direction.

  When the shift amount calculation process is completed in step S109, the image correction process is performed in subsequent step S111. This process corresponds to the above-described image correction process 40d, and the code based on the image data accumulated in the code image / marker image image information storage area 35a based on the shift amount and the shift direction calculated by the shift amount calculation process. The image Pc is returned to the original image data (predetermined position) of the code image Pc.

  That is, the line is returned to the side opposite to the shift direction by the shift amount of each row obtained in step S109. For example, in the example shown in FIG. 6A, since the shift amount of the second row is “+1”, it is returned to the minus side, that is, the left side by one pixel. Similarly, the third to ninth rows are also returned to the left side by the respective shift amounts. As a result, as shown in FIG. 6B, the center guide Mb having the original cross shape is corrected. In the example of FIG. 6, the marker image Pm is corrected. However, the code image Pc can also be corrected to the original code image Pc without image blurring by performing the image correction processing in step S111.

  When image correction processing is performed on the image data stored in the code image / marker image image information storage area 35a in step S111, decoding processing is performed in subsequent step S113. This process targets only the code image Pc out of the code image Pc and the marker image Pm stored in the code image / marker image image information storage area 35a. Therefore, for example, the code image Pc and the marker image Pm are selected based on the difference in brightness of the colors by a filtering process using a gray scale or the like.

  If the code image Pc is a two-dimensional code Q (for example, QR code), the portion of the code image Pc that overlaps the marker image Pm is recovered by a predetermined error correction process even if no code exists. Therefore, the same decoding process as the normal two-dimensional code Q is performed. If the code image Pc is a one-dimensional code (for example, a barcode), the same decoding process as that for the one-dimensional code is performed on a portion of the code image Pc that does not overlap with the marker image Pm. In the case of a one-dimensional code, a line where the code image Pc and the marker image Pm do not overlap may be selected and decoded.

  When the decoding process in step S113 is completed, in the subsequent step S115, a process for determining whether or not the decoding is successful is performed. That is, when the decoding process in step S113 cannot be corrected by the error correction process or when it corresponds to a parity check (check character) error, it is necessary to read the information code such as the two-dimensional code Q again. In this case, the determination process in step S115 is “No”, and the process proceeds to step S101. On the other hand, if the decoding process is normally completed, “Yes” is given, and thus the camera shake correction process is terminated.

  As described above, in the two-dimensional code reader 10 according to the present embodiment, the image data (image information) of the code image Pc and the marker image Pm output from the light receiving sensor 23 is captured by the rolling shutter method and stored in the memory by the image accumulation process 40a. 35 is stored in the code image / marker image information storage area 35a, and the marker image Pm is obtained from the image data (image information) of the code image Pc and the marker image Pm stored in the code image / marker image image information storage area 35a. It is determined and acquired by the marker image acquisition process 40b, and is stored in the marker image image information storage area 35b of the memory 35. Then, based on the marker image Pm acquired by the marker image acquisition process 40b, the shift amount and the shift direction in the row direction of the marker image Pm with respect to the image data (predetermined position) of the reference position of the marker image Pm are determined. Code image Pc based on image data (image information) calculated by the shift amount calculation process 40c and based on the shift amount and shift direction calculated by the shift amount calculation process 40c and stored in the code image / marker image information storage area 35a. Is returned to a predetermined position by the image correction process 40d.

  Thus, for example, even if an image blur occurs in the code image Pc due to the image data (image information) accumulated in the code image / marker image information storage area 35a due to the camera shake of the operator, the shift amount calculation process 40c Since it is possible to return to the original image data (predetermined position) of the code image Pc by the image correction process 40d based on the calculated shift amount and shift direction, it is possible to prevent image blurring.

  The marker image acquisition process 40b, the shift amount calculation process 40c, and the image correction process 40d are realized by an information processing function of the image accumulation process 40a, that is, a function provided by the control circuit 40 (CPU, semiconductor memory, etc.). Therefore, the information processing function of the existing image storage processing 40a is used without adding mechanical and electrical components as in the technologies disclosed in Patent Documents 1 and 2 described in the [Background Art] column. Image blurring can be prevented. Therefore, camera shake can be corrected without causing an increase in product cost, an increase in failure rate, and an increase in the size of the apparatus.

Next, Modification Example 1 of the deviation amount calculation process 40c will be described with reference to FIG.
As shown in FIG. 7A, the deviation amount calculation process 40c ′ of the first modification includes a “deviation part detection process” and a “deviation range determination process”. In the misalignment detection processing, misalignment of the row direction component of the marker image Pm (fourth row column, sixth row column, sixth row column, sixth row column, seventh row column, seventh row) Column, seventh row column, eighth row column, eighth row column, eighth row column, eighth row column, ninth row column, ninth row column, ninth row column, ninth row column , The ninth row of columns) is detected, and the shift range α occupied by the detected shift portion is determined by the shift range determination process.

  Then, as shown in FIG. 7B, the shift amount and the shift direction are calculated for the shift range α and the outer peripheral range β of the shift range α. The calculation of the shift amount and the shift direction is performed in the same manner as the shift amount calculation process 40c described above.

  As a result, the portion in which the row direction component of the marker image Pm is not shifted (1 row, 1 column, 2 rows, 2 columns, 2 columns) is not detected by the shift amount calculation process 40c. It is not included in the range α and is not subject to calculation of the shift amount and shift direction. For this reason, in the deviation amount calculation process 40c, the deviation amount and the deviation direction are calculated except for such a portion where there is no deviation, so that the image data (image information) accumulated in the marker image image information storage area 35b is calculated. Compared to the case of calculating the shift amount and the shift direction for all, the speed of the shift amount calculation process 40c ′ can be improved, and the processing load can be reduced. Accordingly, it is possible to increase the speed of camera shake correction.

Subsequently, Modification 2 of the deviation amount calculation process 40c will be described with reference to FIG.
As shown in FIG. 8, in the shift amount calculation process 40c ″ of the second modification, the second to eighth rows (a plurality of rows) are skipped from the rows constituting the two-dimensional array of m rows and n columns. Deviation amounts are calculated for the row and the ninth row (two or more predetermined rows), and the deviation amounts of the skipped third to eighth rows are calculated based on the deviation amounts of the second and ninth rows. For example, the shift amount in the second row is “+1”, whereas the shift amount in the ninth row is “+5”, so that the correction value is calculated from the average value ((+ 1 + 5) / 2 = + 3) or the like. Ask.

  As a result, for the skipped third to eighth rows, the amount of deviation is indirectly calculated based on the amount of deviation obtained for the second and ninth rows without directly calculating the amount of deviation. Therefore, the speed of the shift amount calculation process 40c ″ is improved as compared with the case where the shift amount and the shift direction are calculated for all the rows of the image data (image information) accumulated in the marker image image information storage area 35b. In addition, it is possible to reduce the load on the control circuit 40. Therefore, it is possible to speed up the camera shake correction.

  In this embodiment, since the rolling shutter system is used for the exposure of the light receiving sensor 23, the minimum value of image blur (camera shake) is the second row (= top row + 1), and image blur (camera shake). Since the maximum value of m is the m-th row (bottom row), the second row and the ninth row are selected in the example shown in FIG. In order to increase accuracy, in the example shown in FIG. 8, for example, three rows of the second row, the sixth row, and the ninth row may be selected.

  In the above-described embodiment, the case where the thickness of the marker image Pm is equivalent to one pixel has been described as an example. However, in the present invention, the marker image Pm is described above even if the thickness of the marker image Pm is equivalent to two pixels or three pixels. Functions and effects similar to those of each example can be obtained.

It is a partial longitudinal cross-sectional view which shows the structure outline | summary of the housing etc. of the two-dimensional code reader which concerns on embodiment of this invention. It is a block diagram which shows the structure outline | summary of the circuit part of the two-dimensional code reader which concerns on embodiment of this invention. 3A is an explanatory view showing an example in which a two-dimensional code is placed in the readable area indicated by the marker light, and FIG. 3B is an example of the marker image formed on the light receiving surface of the light receiving sensor. It is explanatory drawing shown. It is a block diagram which shows the relationship of the image correction process performed by the control circuit of the two-dimensional code reader which concerns on embodiment of this invention, a marker image acquisition process, the deviation | shift amount calculation process, and an image correction process. It is a flowchart which shows the flow of the camera-shake correction process by the two-dimensional code reader which concerns on embodiment of this invention. FIG. 6A is an image diagram in which a marker image formed on a light receiving surface of a light receiving sensor is developed on a memory. FIG. 6A shows an example in which image blurring (camera shake) occurs, and FIG. 6B shows the image of FIG. This is an example after image blur (camera shake) is corrected. Fig. 7 (A) shows an image of a marker image (line width 1 pixel) imaged on the light-receiving surface of the light-receiving sensor developed on a memory. Fig. 7 (A) shows the area before image blurring (camera shake) occurs. FIG. 7B shows an example after cutting out a range where image blurring (camera shake) has occurred. FIG. 7B shows a state after correcting the image blurring of FIG. FIG. 5 is an image diagram in which a marker image (line width: 1 pixel) formed on a light receiving surface of a light receiving sensor is developed on a memory. From the amount of deviation in the second row and the amount of deviation in the ninth row, another row (from the third row to the third row). It is explanatory drawing which shows the case where the deviation | shift amount of (8th line) is estimated and correct | amended.

Explanation of symbols

10 ... Two-dimensional code reader (optical information reader)
DESCRIPTION OF SYMBOLS 20 ... Circuit part 21 ... Illumination light source 22 ... Light receiving element 23 ... Light receiving sensor 23a ... Light receiving surface 25 ... Marker light source 27 ... Imaging lens (imaging optical system)
35. Memory (image information storage means, marker image acquisition means, deviation amount calculation means, image correction means)
35a ... Code image / marker image image information storage area (image information storage means)
35b ... Marker image image information storage area (marker image acquisition means)
40. Control circuit (image information storage means, marker image acquisition means, deviation amount calculation means, image correction means)
40a ... Image accumulation processing (image information accumulation means)
40b ... Marker image acquisition processing (marker image acquisition means)
40c ... Deviation amount calculation processing (deviation amount calculation means)
40d: Image correction processing (image correction means)
Lf ... Illumination light Lr ... Reflected light Ma ... Field guide Mb ... Center guide Mf ... Marker light Mr ... Marker reflected light Pc ... Code image Pm ... Marker image Q ... Two-dimensional code (information code)
R ... object to be read m ... row (row of 2D array)
n ... Column (two-dimensional array column)

Claims (6)

An illumination light source capable of emitting illumination light capable of illuminating the information code;
A light-receiving sensor that forms a light-receiving surface by two-dimensionally arranging light-receiving elements that can receive reflected light that is irradiated and reflected from the illumination light source to the information code;
Marker light that can indicate a predetermined position within the irradiable range of the illumination light, and marker reflected light that is irradiated and reflected on the information code can emit marker light having a component in the column direction of the two-dimensional array of the light receiving elements. A marker light source,
An imaging optical system capable of forming a code image of the information code by the reflected light and a marker image by the marker reflected light on a light receiving surface of the light receiving sensor;
Image information storage means having an information processing function, wherein image information of the code image and the marker image output from the light receiving sensor can be captured and stored by a rolling shutter method by the information processing function; ,
Marker image acquisition means capable of determining and acquiring the marker image from the image information of the code image and the marker image stored in the image information storage means;
Based on the marker image acquired by the marker image acquisition unit, a shift amount calculation unit capable of calculating a shift amount in the row direction of the two-dimensional array and a shift direction of the marker image with respect to the predetermined position;
Image correction means for returning the code image based on the image information accumulated in the image information accumulation means to the predetermined position based on the deviation amount and the deviation direction calculated by the deviation amount calculation means,
The optical information reading apparatus, wherein the marker image acquisition unit, the deviation amount calculation unit, and the image correction unit are realized by the information processing function of the image information storage unit. The deviation amount calculating means includes:
A deviation part detecting means capable of detecting a deviation part of a row direction component of the marker image;
A deviation range determination means capable of determining a deviation range occupied by the deviation portion detected by the deviation portion detection means,
The optical information reading apparatus according to claim 1, wherein the shift amount and the shift direction are calculated for the shift range determined by the shift range determination unit and the outer peripheral range.   The deviation amount calculation means calculates a deviation amount for a predetermined two or more rows by skipping a plurality of rows from among the rows constituting the two-dimensional array, and based on the deviation amounts for these two or more rows, 3. The optical information reading apparatus according to claim 1, wherein an amount of line shift is calculated.   2. The marker image acquisition unit, wherein the marker image is determined from the code image stored in the image information storage unit based on a difference between the reflected light component and the marker reflected light component. The optical information reading device according to any one of?   2. The marker image acquisition unit determines the marker image from the code image stored in the image information storage unit based on a difference between a luminance of the reflected light and a luminance of the marker reflected light. The optical information reading device according to any one of?   The optical information reading apparatus according to claim 1, wherein the marker light is irradiated so as to form a substantially cross shape on the information code.

Images