Patent Publication Number: US-2012024952-A1

Title: System and method for identifying qr code

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a two-dimension barcode, and especially to a system and method for identifying a QR (Quick Response) code formed on a metal surface. 
     BACKGROUND OF THE INVENTION 
     A two-dimension barcode is a new technology of information storage and transmission, being widely used in various applications, including product identification, security and anti-counterfeiting, and E-commerce. The two-dimension barcode records data information with specific geometric patterns of black and white graphic symbols arranged in two-dimension directions. The concept of logical basis of “0” and “1” bit stream adopted in computer systems is utilized to form graphic symbols that correspond to binary representation of text and numerical information. The graphic symbols can be read by an image input device or a photoelectric scanning device to achieve automatic information processing. 
     The International standards of the two-dimension barcode include, for example, PDF417, Data Matrix, Maxi Code, and QR (Quick Response) Code, among which QR code is most widely used. The QR code shows an advantage of high-speed and all-direction (360 degrees) accessibility, and is capable of representation of Chinese characters, rendering QR code wide applicability in various fields. The QR code comprises a square array of a series of small square message blocks, in which “0” or “1” are represented through variation of gray levels of bright and dark blocks. For applications such as automobile manufacturing, aircraft manufacturing, weapon manufacturing, and various mechanical products, the QR code must be formed via engraving on a metal surface or a plastic surface. However, the QR code formed thereof through engraving leads to a contrast between bright and dark blocks that has poorer quality than a contrast obtained in a printed surface. This makes the identification of QR code on a metal surface difficult, eventually resulting in distortion of identified data. 
     Therefore, it is desired to have a system and method for identifying a QR code to overcome the aforesaid drawbacks. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a highly stable and identifiable system for identifying a QR (Quick Response) code. 
     Another objective of the present invention is to provide a highly stable and efficient method for identifying a QR code. 
     To achieve the foregoing objectives, according to an aspect of the present invention, a system for identifying a QR code is provided, comprising a camera module and a processor electrically coupled to the camera module. The camera module has a first camera, a second camera, a controller, a uniform light source, a memory, and a power regulator. The first camera comprises a first lens and a first sensor coupled to the first lens, and the second camera comprises a second lens and a second sensor coupled to the second lens. The controller is simultaneously coupled to the first sensor and the second sensor, and the controller is coupled to the processor. The uniform light source and a memory are respectively electrically coupled to the controller. The power regulator is respectively electrically coupled to the first sensor, the second sensor, the controller and the processor. Accordingly, the first lens faces toward a predetermined first datum surface, and an optical axis of a centre of the first lens intersects a predetermined second datum surface at a focal point of the first lens. The first lens is located between the second lens and the uniform light source, and the first lens, the second lens and the uniform light source are located at the same plane. A centre of the second lens is located at a reflected ray which is emitted from an optical axis of the uniform light source through the focal point on the predetermined second datum surface. 
     According to another aspect, the present invention further provides a method for identifying the QR code, the method comprises the steps of: utilizing a first camera and a second camera to simultaneously obtain a first image and a second image representing the QR code; forming a third image via geometrically transforming the second image into a normal square shape of the QR code; subtracting each pixel value of message unit blocks of the first image and the third image from the average pixel value of the first image and the third image and then calculating an absolute value to respectively form a fourth image and a fifth image; comparing each of corresponding pixels of the fourth image and the fifth image to form a sixth image; and setting a threshold to binarize the sixth image. 
     As mentioned above, the system and method for identifying the QR code according to the present invention employ the design of the two cameras according to the concept of a differential signal formed thereof. The QR code can be efficiently and stably identified by tilting the two cameras and light emission. The objective of the highly stable and efficient method for identifying the QR code is achieved by the steps of transforming the image, subtracting the corresponding pixel values, calculating the absolute value, setting the threshold to determine the area is 0 or 1, and then identifying the QR code. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic top view illustrating a QR code according to the present invention. 
         FIG. 2  is a schematic perspective view of the structure of a white message unit blocks representing a bright plane of the QR code of  FIG. 1 . 
         FIG. 3  is a schematic perspective view of the structure of a black message unit blocks representing a scattering plane of the QR code of  FIG. 1 . 
         FIG. 4  is a flow chart illustrating a manufacturing method of the QR code according to the present invention. 
         FIG. 5  is a block diagram illustrating a system for identifying a QR code according to the present invention. 
         FIG. 6  is a schematic diagram illustrating a concept for identifying a QR code according to the present invention. 
         FIG. 7  is a schematic diagram illustrating the first camera and the second camera are simultaneously connected to the controller shown in  FIG. 5 . 
         FIG. 8  is a flow chart illustrating a method for identifying a QR code according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. 
     With reference to the drawings and in particular to  FIGS. 1-3 , a QR code according to the present invention, generally designated as  10 , is applicable to formation on a metal surface or a plastic surface. The QR code  10  is a square block composed of a plurality of message unit blocks, which are square, arranged without gaps according to certain rules. The message unit blocks include white and black blocks respectively representing different binary values. In accordance with one preferred embodiment of the present invention, the white message unit blocks of the QR code  10  are represented as bright planes  11  formed on a metal surface through die casting. The bright planes  11  of the white message unit blocks are set at an inclination angle φ with respect to a horizontal plane. Preferably, the angle φ is between 0 and 45 degrees. 
     The black message unit blocks of the QR code  10  are represented as scattering planes  12  in accordance with one preferred embodiment of the present invention. The scattering planes  12  are formed on the same plane, which is parallel to the horizontal plane. With the white and black message unit blocks of the QR code  10  represented as bright planes  11  and scattering planes  12 , the contrast therebetween is enhanced, as well as readability and stability are improved. 
     Reference is now made to  FIG. 4  for illustrating a manufacturing method of the QR code  10 . The method of  FIG. 4  begins at step S 001 . 
     At step S 001 , die casting is performed to form bright planes on a metal surface respectively corresponding to message unit blocks that constitute the QR code, which the bright planes of the message unit blocks are set at an identical inclination angle with respect to a horizontal plane. 
     At step S 002 , a laser engraving machine is used to remove one or more of the bright planes corresponding to positions of black message unit blocks of the QR code to form scattering planes that are set on the same plane parallel to the horizontal plane. 
     Specifically, the manufacturing method further comprises a step of forming a positioning block  13  through die casting in front of the step S 001 , wherein the QR code  10  is formed on one side of the positioning block  13  with edges of the QR code  10  respectively perpendicular to edges of the positioning block  13 . As indicated by the positioning block  13 , bright planes  11  can be easily formed on a metal surface with identical inclination through die casting, the laser engraving machine may easily acquire position information of the QR code  10  to accurately and quickly remove the bright planes  11  corresponding to the black message unit blocks of the QR code  10  for forming desired scattering planes  12 . 
     Referring to  FIG. 5 , the system for identifying a QR code according to the present invent comprises a camera module and a processor  270  electrically coupled to the camera module. The camera module has a first camera  210 , a second camera  220 , a uniform light source (LS)  230 , a power regulator  240 , a memory  250  and a controller  260 . The first camera  210  and the second camera  220  are simultaneously coupled to the controller  260 . The uniform light source  230  and the memory  250  are respectively electrically coupled to the controller  260 . The power regulator  240  is respectively electrically coupled to the first camera  210 , the second camera  220 , the controller  260  and the processor  270 . The controller  260  is coupled to the processor  270 . The memory  250  herein is utilized to store image data. The processor  270  herein is a computer terminal for supplying power to the first camera  210 , the second camera  220  and the controller  260  via the power regulator  240 . 
     Referring to  FIG. 6  and  FIG. 7 , specifically, the first camera  210  comprises a first lens  212  and a first sensor  214 , and the second camera  220  comprises a second lens  222  and a second sensor  224 . The first lens  212  and second lens  222  are used to collect images; in addition, the first sensor  214  and the second sensor  224  are simultaneously coupled to the controller  260 . A predetermined first datum surface  280  and a predetermined second datum surface  290  are located as shown in  FIG. 6 . The predetermined first datum surface  280  is parallel to a horizontal plane, and the angle between the predetermined first datum surface  280  and the predetermined second datum surface  290  is equal to the tilt angle φ. The first lens  212  is facing toward the predetermined first datum surface  280 , and an optical axis L 1  of a centre of the first lens  212  intersects a predetermined second datum surface  290  at a focal point  0  of the first lens  212 . In addition, the first lens  212  is located between the second lens  222  and the uniform light source  230 ; in addition, the first lens  212 , the second lens  222 , and the uniform light source  230  are located at the same plane. Moreover, a centre of the second lens  222  is located at a reflected ray L 3  which is emitted from an optical axis L 2  of the uniform light source  230  through the focal point  0  on the predetermined second datum surface  290 . 
     The system for identifying the QR code  10  of the present invention employs the design of tilting the two cameras and light emission. Specifically, the first lens  212  faces toward the QR code  10  is for collecting images, that is, the bright planes  11  is corresponding to the predetermined first datum surface  280 , and the scattering planes  12  is corresponding to the predetermined second datum surface  290 . The first lens  212  is perpendicular to the scattering planes  12  and intersects the bright planes  11  at the focal point  0 . In addition, the angle between the first lens  212  and a normal line L 4  at 0 of the bright planes  11  is φ. The two angles between the optical axis L 2  of the uniform light source  230  and the normal line L 4  and between the centre of the second lens  222  and the normal line L 4  are θ, which is larger than φ. If the bright planes  11  are smooth metal surfaces to collect images, the second lens  222  receives a brighter value of pixel via a strengthened image from the uniform light source  230 . The subtraction between collected brightness values from the two cameras is greater than 0. Besides, on a black block (i.e., the scattering planes  12  represent the black message unit block), the bright planes  11  are formed as a non-smooth scattering surfaces  12  by a laser engraving machine, so the collected brightness values from the first lens  212  and the second lens  222  are similar, and thereby the subtraction between collected brightness values from the two cameras is closed to 0. Accordingly, the decoding can be implemented by setting a threshold to distinguish “0” and “1”. 
     Specifically, referring to  FIG. 7 , a CMOS image sensor chip or a CCD sensor chip can be used as the sensor. Take an OV series camera chip for example, when the chip is simultaneously coupled to the controller  260 , the data pins of the first sensor  214  and the second sensor  224  respectively connected to the I/O pins of the controller  260  for transmitting the image signals obtained by the sensors to the controller  260 . The corresponding SENSOR_RESET pins,  12 C CLK pins,  12 C Data pins, MCLK pins of the first sensor  214  and the second sensor  224  are simultaneously coupled to the controller  260 . In addition, the HSYNC pin, VSYNC pin and PIXEL CLK pin are individually connected to the controller  260 . More specifically, the SENSOR_RESET Pins are utilized to make the first sensor  214  and the second sensor  224  simultaneously into the initialization state. The common  12 C CLK pin and  12 C Data pin for the two sensors are utilized to process command settings of the initialization state. One group of functional signal pins: HSYNC/VSYNC/PIXEL CLK pin are utilized to implement synchronization signals, thereby receiving the image data of both the two sensors. 
     Referring to  FIG. 8 , the method for identifying the QR code begins at step S 101 . 
     At step S 101 , the system for identifying QR code is utilized to collect images, that is, a first camera and a second camera are utilized to simultaneously obtain a first image and a second image representing the QR code. 
     At step S 102 , a third image is formed via geometrically transforming the second image into a normal square shape of the QR code. 
     At step S 103 , each pixel value of message unit blocks of the first image and the third image is subtracted from the average pixel value of the first image and the third image, and then an absolute value is calculated to respectively form a fourth image and a fifth image. 
     At step S 104 , each of corresponding pixels of the fourth image and the fifth image is compared, and then a difference is recorded to form a sixth image. 
     At step S 105 , a threshold is set to binarize the sixth image. 
     Due to different collecting angles of the first lens  212  and second lens  222 , the obtained images with geometric distortion, which the bar code image is not a square shape but a quadrilateral shape, are caused by the camera angle of the second lens  222 . Therefore, step S 102  is needed to geometrically transform the obtained images to correct the geometric distortion. The QR code is identified in the sixth image by deciding closed to 0 or from 0. According to the characteristics of the camera for selecting the appropriate threshold to distinguish “0” and “1” thereby decoding as binary digits, the objective of a highly efficient and stable method for identifying the QR code is achieved by aforesaid steps. 
     As mentioned above, the system and method for identifying the QR code according to the present invention employ the design of the two cameras according to the concept of a differential signal. The QR code can be identified efficiently and stably by tilting the two cameras and light emission. The objective of the highly stable and efficient method for identifying the QR code is achieved by the steps of transforming the image, subtracting the corresponding pixel values, calculating the absolute value, setting the threshold to determine the area is 0 or 1, and then identifying the QR code. 
     While the preferred embodiments of the present invention have been illustrated and described in detail, various modifications and alterations can be made by persons skilled in this art. The embodiment of the present invention is therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications and alterations which maintain the spirit and realm of the present invention are within the scope as defined in the appended claims.