WO2009107570A1

WO2009107570A1 - Code reader

Info

Publication number: WO2009107570A1
Application number: PCT/JP2009/053124
Authority: WO
Inventors: トーカーギャレット
Original assignee: 株式会社東研
Priority date: 2008-02-26
Filing date: 2009-02-17
Publication date: 2009-09-03
Also published as: JP2009205228A; JP4440312B2

Abstract

A code reader is provided with a case having a readout opening section; a first light source means which irradiates a two-dimensional area, including a code, with illuminating light from above through the readout opening section; a second light source means which irradiates the two-dimensional area, including the code, with illuminating light from a diagonal direction through the readout opening section; an imaging means which receives first light source reflection light, which is reflection light of illuminating light emitted from the first light source means and reflected from the two-dimensional area, and second light source reflection light, which is reflection light of illuminating light emitted from the second light source means and reflected from the two-dimensional area; an image processing section which generates an image for code readout by performing differential processing to an image formed by the first light source reflection light and an image formed by second light source reflection light; and a decoder means which reproduces prescribed data which corresponds to a code, based on the image for code readout.

Description

Paper Code Reader Technical Field

The present invention relates to a code reader that optically reads a two-dimensional code or the like formed on the surface of an object, and more specifically, an imaging unit and an image processing unit so that the code can be read with high accuracy. Relates to an improved code reader. Background art

In recent years, one-dimensional or two-dimensional codes in which information such as product and part numbers, product names, and prices are symbolized with black and white stripes are widely used to quickly recognize management information for products and parts. ing. The pattern of these codes is represented by marks with different reflectivities. For example, in a one-dimensional code, a series of numbers and letters are represented by a combination of line width ratios. And various information such as part numbers, names, and prices are replaced with the above numbers and letters.

For example, a code represented by a bar code is read by a reading device called a bar code reader. This bar code reader is a device that hits light on a bar code, receives light returned from white and black stripes with different reflectivities, and decodes them into original numbers based on the intensity of the reflected light. It is. There are two types of code readers: a hand-held type that allows the operator to hold the device in hand, and a stationary type that allows a product with a bar code to pass over the reading window. is there.

Of these, hand-held (handy type) code readers are widely used in supermarkets, department stores, convenience stores, etc. as point-of-sale (POS) (point-of-sales information management) systems. 0 0 0—see 2 9 8 6 9 8). FIG. 1 is a perspective view showing an example of a general hand-held bar code reader. In the figure, the main body of the bar code reader 1 0 0 1 0 1 Has a substantially rectangular parallelepiped shape with a “L” cross section. A code reading unit 10 2 is provided at the tip of one end of the main unit 10 1, and the data of the read code is registered, deleted, displayed, guidance, etc. on the upper surface of the other end of the main unit 1 0 1. There are provided a numeric keypad 10 3 for inputting the command and a display unit 10 4 including a liquid crystal panel for displaying predetermined items.

When using the code reader 1 0 0, the user holds the other end of the main body 1 0 1 with one hand and presses the reading unit 1 0 2 against the code to be read, and the side surface of the main body 1 0 1 Press the trigger button 1 0 5 provided in the section. Then, since the code is read via the reading unit 102, the user presses a predetermined numeric keypad 103 and inputs a command for registering and displaying the data of the code.

Conventionally, this type of handy-type code reader has been targeted for one-dimensional codes and two-dimensional codes encoded in black and white patterns. However, in recent years, in the field of handling industrial products and the like, an apparatus for reading a two-dimensional code or a one-dimensional code directly marked on the surface of an object such as metal, ceramics, or a polymer compound has been developed.

Currently, there are dot beans and laser markers in this direct patterning identification (DPMI) technique. Among these, the dot bean is marked by denting the surface of the product, so it is characterized by excellent durability and printing that does not disappear.For example, it is used for product management such as engine blocks. .

Conventionally, a code reading device used to read a code that has been directly dot-marked on a glossy surface of metal or the like irradiates oblique illumination light as means for irradiating the code that is the object to be read. Thus, a means for picking up an image and a means for picking up an image by irradiating coaxial incident illumination light have been used. Among these, in the image generated by the former image pickup means, a bright code portion (dot portion) is projected on a dark background, while in the image generated by the latter image pickup means, the image is dark on a light background. The old code part is projected.

If the light reflection characteristics of the metal being read are uniform, one of the imaging means can be used depending on the characteristics, but in reality, various types of metals with different light reflection characteristics, etc. It is necessary to read the code marked on the surface. For this reason, in conventional code readers, if the appropriate conditions for each imaging means are not met, scratches on the surface, cutting marks such as hairlines, surface irregularities such as skins, and skin marks are captured images. There was a problem that the image quality deteriorated by appearing as dot-like image noise above, and the code could not be read accurately. Disclosure of the invention

Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to provide a highly accurate code even when the reflection characteristics of light on the surface of the reading object on which the code is formed are different. It is an object of the present invention to provide a code reader that can be read and that is easy to set up and use.

The object of the present invention is to provide a code reading device for optically reading a code marked on the surface of an object to be read, a housing having a reading opening, and the code through the reading opening. First light source means for irradiating illumination light to the two-dimensional area from the incident direction, second light source means for irradiating illumination light to the two-dimensional area from the oblique direction via the reading opening, and the first light source. First illumination light reflected from the two-dimensional area and illumination light from the second light source reflected from the second dimension area are reflected through the reading aperture. Imaging means for receiving light, an image processing unit for generating a code reading image by performing differential processing between the image of the first light source reflected light and the image of the second light source reflected light, and the code reading image Corresponding to the code based on By and a decoder means for reproducing Isseki de, is achieved.

Further, the object is that the imaging means is a color camera, and The illumination light of the one light source means and the illumination light of the second light source means are light of different colors, respectively, and the force beam is irradiated from the first light source means and the second light source means simultaneously. The reflected light of the illumination light is imaged, and the image processing unit separates the captured image of the color camera based on the color component of the illumination light, whereby the image of the first light source reflected light and the first light source are separated. The two light source reflected light image is generated effectively.

Further, the above object is effectively achieved by the fact that the color of illumination light of the first light source means and the second light source means is any one of red, green, and blue.

Further, the object is to provide the first illumination unit and the reading opening between the first illumination unit and the reading opening unit.

(1) An optical filter that allows only the wavelength component of the illumination light of the illuminating means to pass therethrough is provided, and the optical filter is effectively achieved by having a hole at a location that intersects at least the field of view of the imaging means. .

Further, the above object is effectively achieved by arranging the image processing unit in the casing.

According to the code reading apparatus of the present invention, an image obtained by irradiating the code to be read with illumination light from the incident direction and an image obtained by irradiating the code with illumination light from the oblique direction. The code reading image is generated by performing the difference processing. As a result, an image for code reading from which the noise on the glossy surface of the object to be read is removed is generated, and stable and highly accurate code reading can be executed.

In addition, the image pickup means is a color camera, and the first light source means (epi-illumination direction) and the second light source means (diagonal direction) are illuminated with different colors of illumination light, and the image is irradiated simultaneously from the epi-illumination direction and the oblique direction. Images were taken, and the captured images were separated based on the color components of the illumination light, so that images for each illumination direction could be obtained. As a result, the number of times of imaging for one code can be reduced to one, so the imaging time is greatly reduced. At the same time, it is possible to perform reading that is strong against blurring caused by subject movement due to movement of the code and camera movement due to movement of the reading device.

In addition, an optical filter that allows only the wavelength component of the illumination light of the first light source means to pass is provided between the first light source means and the reading aperture, and the central portion of the optical filter that intersects the field of view of the imaging means is provided. A hole was drilled in. Accordingly, it is possible to prevent the generation of a false image that occurs when a part of the illumination light emitted from the second light source unit is reflected by the reading target and then re-reflected by the first light source unit. Brief Description of Drawings

FIG. 1 is a perspective view showing an example of a general hand-held bar code reader.

FIG. 2 is a cross-sectional view schematically showing the basic configuration of the code reader according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an optical path of oblique illumination light.

FIG. 4 is an image of a reading object imaged using oblique illumination light. FIG. 5 is an explanatory view showing the optical path of the epi-illumination light.

FIG. 6 is an image of a reading object imaged using epi-illumination light. FIG. 7 is a block diagram showing an image processing flow of the code reading apparatus according to the first embodiment.

FIG. 8 is an image of the read object that has been subjected to image processing.

FIG. 9 is a block diagram showing a modification of the image processing flow of the code reading apparatus according to the first embodiment.

FIG. 10 is a cross-sectional view of an essential part schematically showing a basic configuration of a code reading apparatus according to a second embodiment of the present invention.

FIG. 11 is a mirror image captured by providing an optical filter between the incident light source and the reading aperture. Fig. 12 shows a mirror image taken without an optical filter between the incident light source and the reading aperture. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the embodiments described below, a dot-shaped coordinate mark (DPMI) is provided on the surface of a reading object made of metal or the like. The present invention is applied to a handy type code reading device that reads a needle.

[First embodiment]

FIG. 2 is a cross-sectional view schematically showing the basic configuration of the code reading device according to the embodiment of the present invention according to the first embodiment of the present invention. In FIG. 1, a code reading device 1 has a housing 2 formed in an L-shaped cross section that can be operated by a user with one hand. A reading opening 2 is provided at one end of the housing 2. a is formed, and a trigger button 3 for image capture is provided at the bent portion. The code 5 marked on the surface of the reading object (metal plate or the like) 4 is optically read by the code reading device 1 through the reading opening 2a.

The code reader 1 includes an incident light source (first light source) 6 that irradiates illumination light 6 L from the incident direction onto a two-dimensional area including the code 5 through the reading opening 2 a inside the housing 2, An oblique light source (second light source) 7 that irradiates illumination light 7 L obliquely onto the two-dimensional area through the opening 2 a and imaging that receives reflected light of the illumination light irradiated on the two-dimensional area A unit 8 and an image processing unit 9 for processing an image captured by the imaging unit 8.

The image pickup unit 8 is a color camera such as a CCD type or a MOS type, and has a lens 8 a that focuses the picked-up image on the color camera, and is substantially at the center of the reading opening 2 a. It is arranged above the part. Note that the two long dotted lines extending downward from the imaging unit 8 indicate the outer edge of the visual field 8 V of the imaging unit 8, and this visual field 8 V is slightly smaller than the reading aperture 2a. Is set to In addition, the optical axis of the camera of the image pickup unit 8 is preferably inclined by about 10 ° with respect to the incident direction, so that the reflection of the ghost image of the light receiving unit can be removed from the field of view 8 V. it can.

The incident light source 6 and the direction light source 7 are composed of a high-intensity LED array and the like, and both emit light of different colors. In particular, the color used for these illumination lights 6 L and 7 L is preferably one of the three primary colors (red, green, and blue). In this embodiment, the oblique light source 7 emits red light. On the other hand, an LED that emits green illumination light is used as the incident light source 6. The oblique light source 7 preferably has an incident angle of the illumination light 7 L (an angle formed between the surface of the cord 5 and the incident light beam) of 35 to 55 °, and particularly preferably 45 °.

In the code reading device 1 having such a configuration, the trigger button 3 is placed with the reading opening 2a of the housing 2 close to the surface of the reading object 4 marked with the code 5 in a substantially parallel manner. The illumination light 6 L and 7 L are irradiated from the incident light source 6 and the oblique light source 7 to the reading object 4 through the reading opening 2 a, and the reflected light from the reading object 4 is reflected. The two-dimensional area image including the code 5 is picked up by being received by the image pickup unit 8 through the reading opening 2 a.

FIG. 3 is an explanatory diagram showing an optical path of oblique illumination light, and FIG. 4 is an image of a reading object imaged using the oblique illumination light. As shown in FIG. 3, out of the oblique illumination light 7 L emitted from the oblique light source 7, the light reflected by the code 5 in which the dot-shaped recess is formed is received by the imaging unit 8, On the other hand, the light reflected by the surface of the reading object 4 around the code 5 is not received by the imaging unit 8. Therefore, as shown in FIG. 4, in the image obtained by capturing the reflected light of the oblique illumination light 7 L, the code 5 is roughly white and the surface of the reading object 4 around the code 5 is black. However, reading Scratches such as cutting marks formed on the surface of the object to be picked up 4 also appear white, and the overall clarity of the rectangular code 5 is low.

FIG. 5 is an explanatory diagram showing the optical path of the epi-illumination light, and FIG. 6 is an image of the reading object imaged using the epi-illumination light. As shown in FIG. 5, out of the epi-illumination light 6 L emitted from the epi-illumination light source 6, the light reflected by the surface of the object 4 to be read around the code 5 is received by the imaging unit 8, while the code The light reflected at 5 is not received by the imaging unit 8. Therefore, as shown in FIG. 6, the image obtained by reflecting the reflected light of the epi-illumination light 6 L has the code 5 roughly black and the surface of the reading object 4 around the code 5 white. However, scratches such as cutting marks formed on the surface of the reading object 4 also appear dark, and the sharpness of the upper side of the rectangular cord 5 is particularly low.

FIG. 7 is a block diagram showing an image processing flow of the code reading apparatus according to the present embodiment. In this figure, a reading object 4 including a code (mark) 5 irradiated with oblique illumination light 7 L and epi-illumination light 6 L is imaged by a color camera (imaging unit) 8, and the captured image The image processing unit 9 sent to the image processing unit 9 provided in the housing 2 first separates the captured image captured by the color camera 8 based on the color components, and outputs a color-specific image (R ( Red light) image, G (green light) image, and B (blue light) image). In the present embodiment, the image shown in FIG. 4 is an image A (R image) generated based on the reflected light of the oblique illumination light 7 L (red light emission), and shown in FIG. The image is an image B (G image) generated based on reflected light of epi-illumination light 6 L (green light emission).

Next, the image A and the image B generated based on the color components of the illumination lights 6 L and 7 L are subjected to differential processing based on the following [Equation 1], and a decoded image for reading the code 5 is obtained. Generate.

[Formula 1] C = (A * 0 ffs— A)-(B * 0 ffs— B)

I F C> 255 THEN C = 255

IF C 0 0 THEN C = 0

Here, “A” is a pixel value (0 to 255) in the image A at a predetermined position, and “〇 ff s_A” is an offset value (0.1 to 2.0) depending on the setting of the imaging unit 8. It is. “B” is the pixel value (0 to 255) in the image B at the same position, and “〇ffs—B” is the offset value (0.1 to 2.0) depending on the above setting. . Furthermore, “C” is a pixel value obtained as a result of the above difference processing.

The decoded image generated by the image processing unit 9 is copied based on the image data.

—The data recorded in code 5 is output to a decoding unit (not shown) that reproduces the data, and the predetermined data corresponding to code 5 is reproduced.

Fig. 8 shows a decoded image generated by differential processing of the two images A and B. Comparing this decoded image with the color-by-color images in Figs. 4 and 6, the decoded image in Fig. 8 erases scratches such as cutting marks formed on the surface of the object 4 to be read. It can be seen that 5 is displayed more clearly.

In the present embodiment, the oblique illumination light 7L is emitted in red and the incident illumination light 6L is emitted in green. However, the present invention is not limited to this, and the oblique illumination light 7L and As long as the illumination light of a different color is used for the epi-illumination light 6 L, the emitted color and combination may be any.

As described above, in the code reading device 1 according to the present embodiment, the image B based on the reflected light of the incident illumination light 6 L and the oblique illumination light 7 L for the code 5 formed on the surface of the reading object 4. The image A based on the reflected light is generated and the two images A and B are subjected to differential processing to generate a decoded image with high definition. As a result, the noise on the glossy surface of the reading object 4 in the decoded image is removed, and stable and highly accurate code reading can be performed. In the code reading device 1 according to the present embodiment, the imaging unit 8 is a color camera, and illumination light of different colors is used for the incident light source 6 and the oblique light source 7, and the light sources 6 and 7 are simultaneously emitted. Images were captured as they were, and the captured images were separated based on the color component of the illumination light to generate images A and B for each illumination direction. As a result, the number of times of imaging for one code 5 can be reduced by one, so the imaging time is greatly reduced, and the subject is not subject to blur due to the movement of code 5, and the camera is resistant to camera shake due to the movement of code reader 1. Can be executed.

FIG. 9 is a block diagram showing a modification of the image processing flow of the code reading apparatus according to the present embodiment. In this modified example, by pulling the trigger button 3, one of the incident light source 6 and the oblique light source 7 is activated, and an image of the reading object 4 is picked up by the image pickup unit 8. The other light source is activated and the image of the reading object 4 is picked up by the image pickup unit 8. The two captured images A and B are sent to the image processing unit 9 respectively. The image processing unit 9 performs differential processing on the captured image A and the captured image B based on the above-described [Equation 1] to generate a decoded image for reading the code 5.

With the configuration as described above, in this modified example, similarly to the first embodiment described above, a decoded image with high definition can be obtained, and the present invention is not limited to power image capturing, for example, monochrome imaging is adopted. As a result, the cost of component parts can be reduced. [Second Embodiment]

FIG. 10 is a cross-sectional view of an essential part schematically showing a basic configuration of a code reading apparatus according to a second embodiment of the present invention. In the figure, the same members as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

In the code reader 1 ′ according to the present embodiment, the first embodiment described above is provided in that the optical filter 10 is disposed between the incident light source 6 and the reading opening 2 a. It is different from the form. The optical filter 10 is configured to allow only the epi-illumination light 6L to pass therethrough, and a hole 10a is formed in the center thereof. The hole 10 a is provided so that the imaging unit 8 can capture the oblique illumination light 7 L reflected by the code 5. Therefore, at least a portion of the optical filter 10 that intersects the visual field 8 V of the imaging unit 8 is formed with the hole 10 a.

FIG. 11 is a mirror image taken with the optical filter 10 placed between the epi-illumination light source 6 and the reading opening 2a, and FIG. 1 2 does not have this optical filter 10. It is the image of the mirror surface imaged in (1). Comparing these figures, it can be seen that the image in FIG. 12 has more light spots than the image in FIG. That is, this result is that a false image generated by re-reflecting by the incident light source 6 after a part of the oblique illumination light 7 L is reflected by the reading object is cut by the optical filter 10. It means that.

In the code reading device 1 ′ according to the present embodiment having the above-described configuration, the incident light source 6, the reading opening 2 a, and the like can be obtained in addition to the same operational effects as the first embodiment described above. In the meantime, the provision of the optical filter 10 that allows the incident illumination light 6 L to pass through prevents the oblique illumination light 7 L from being reflected again by the incident light source 6 to prevent the generation of false images. it can. As a result, the occurrence of erroneous code recognition due to false images can be reduced, and more accurate code reading can be performed.

The embodiment of the present invention has been specifically described above, but the present invention is not limited to this, and can be appropriately changed without departing from the spirit of the present invention.

Claims

Scope of request A code reader for optically reading a code marked on the surface of an object to be read.

A housing having a reading opening;

First light source means for irradiating illumination light from the incident direction to the two-dimensional area including the code through the reading opening;

Second light source means for irradiating illumination light from the oblique direction to the two-dimensional area through the reading opening;

The first light source means reflects the first light source reflected from the two-dimensional area, and the second light source reflected from the two-dimensional area reflects the second light source reflected from the reading opening. Imaging means for receiving light via,

An image processing unit that generates a code reading image by performing differential processing between the image of the first light source reflected light and the image of the second light source reflected light;

Decoder means for reproducing predetermined data corresponding to the code based on the code reading image;

A code reading device comprising: The imaging means is a color camera, and the illumination light of the first light source means and the illumination light of the second light source means are light of different colors, and the color camera is the first light source. Imaging reflected light of the illumination light irradiated simultaneously from the means and the second light source means, and

The image processing unit generates the image of the first light source reflected light and the image of the second light source reflected light by separating a captured image of the color camera based on a color component of the illumination light. Item 2. The code reader according to item 1.

3. The code reader according to claim 2, wherein the color of illumination light of the first light source means and the second light source means is any one of red, green, and blue.

4. An optical filter for passing only a wavelength component of illumination light of the first illumination means is provided between the first illumination means and the reading aperture, and

4. The code reader according to claim 2, wherein the optical filter has a hole at least at a location where it intersects the field of view of the imaging means.

5. The code reading device according to claim 1, wherein the image processing unit is disposed in the housing.