JP2005165802A - Optical information reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information reading apparatus enabling focus adjustment at relatively high speed, with a simple structure without provision of a device such as a sensor for measuring a distance to automatically adjust a focal position. <P>SOLUTION: An imaging means 2 images light reflected from optical information 1 onto a conversion means 3 having an imaging device, so that the light is converted into an image signal. An image storing means 4 preserves the image signal into an image memory. A recognition means 5 recognizes existence of the optical information from the image signal stored in the image memory. The position of the imaging means 2 is shifted by controlling a transfer means 7 until the recognition becomes successful. Further, a decode means 6 for decoding the optical information from the image signal stored in the image memory is structured to control the transfer means 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical information reader for reading optical information.

  Optical information readers that read optical information such as one-dimensional codes such as barcodes and two-dimensional codes generally read optical information with a fixed-focus lens, and the distance from the optical information is fixed. For the device to be used, the focus is adjusted in advance according to the position of the target optical information, and for the hand-held device, the operator can read it by moving it to an appropriate position. . However, if the target optical information code size is large, the field of view must be increased. If the optical information component is small, the field of view must be narrowed to increase the resolution. Must not. This cannot be realized by a single optical information reader having a fixed-focus lens. In order to solve such a problem, an optical information reading apparatus having a function of changing a focal position has been proposed (for example, see Patent Document 1).

  FIG. 8 shows an example of this optical information reader.

In FIG. 8, in the hand-held reader 23 having the image pickup means 24 for reading the image of the optical information 1, a light beam that irradiates a light beam that forms a predetermined angle with respect to the optical axis of the lens system of the image pickup means 24. The amount of displacement calculated by the irradiation unit 26, the amount of displacement of the image position of the light beam with respect to the optical axis from the image captured by the image capturing unit 24, and the amount of displacement calculated by the amount of displacement calculation unit are used as autofocus information. And a control unit 25 that adjusts the focal position by moving the lens system or the imaging device of the imaging unit 24 in the optical axis direction.
JP 2002-56348 A

  In order to realize the autofocus mechanism as described above, a device for irradiating a light beam, a sensor for measuring a distance, and the like are separately required, and there is a problem that the configuration becomes complicated.

  In the present invention, when optical information is read, it is not necessary to accurately adjust the focus required for a camera or the like, and even if the image is not somewhat clear, it is corrected in the process of binarization and is accurately obtained as information. Focusing on the fact that it is possible to read, it is possible to adjust the focal position in order to read the difference in code size and resolution of optical information with one optical information reader, and It is an object of the present invention to provide an optical information reading apparatus capable of adjusting the focus at a relatively high speed with a simple configuration that does not have a device such as a sensor for measuring a distance for automatic adjustment.

  In order to solve the above-described problems, an optical information reading apparatus according to the present invention includes an image forming unit that forms an image of light reflected from optical information, and an image signal that receives light formed by the image forming unit. Conversion means for converting the image signal, image storage means for storing the image signal, recognition means for recognizing the presence of optical information from the image signal, decoding means for decoding optical information from the image signal, Moving means for moving the position of the imaging means when the recognition means cannot recognize optical information.

  As described above, according to the present invention, it is possible to adjust the focal position in order to read the difference in the code size and resolution of the optical information with one optical information reader, and the focal position is automatically adjusted. By not having a device such as a sensor for measuring the distance for adjustment, it is possible to provide an optical information reader capable of adjusting the focus at a relatively high speed with a simple configuration.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram of an optical information reading apparatus of the present invention.

  The light emitted from the optical information reader and reflected by the optical information 1 is received by the image forming means 2 constituted by a lens or the like, and the light imaged by the image forming means 2 is received and converted into an image signal. An image is formed at a predetermined position of the conversion means 3 constituted by an imaging element such as a CCD or CMOS sensor.

  Then, depending on the positional relationship among the optical information 1, the image forming means 2, and the converting means 3, the image formed on the converting means 3 may be clear or unclear.

  The image signal output from the conversion unit 3 is stored as image information in the image storage unit 4.

  The recognition unit 5 determines whether or not the optical information 1 is present in the image stored in the image storage unit 4. In the present embodiment, this recognition means binarizes an image and examines the presence of characteristic information possessed by various optical information, and does not actually perform decoding processing. Therefore, the presence or absence of optical information can be checked at a relatively high speed, and even when the position of the imaging means is moved based on this information, the imaging means can be moved to an appropriate position at a sufficiently high speed. Is possible. Needless to say, even if decoding fails, it is necessary to move the imaging means, but it takes a relatively long time to adjust the focus if it is decided whether to move after performing the decoding process. In the present invention, the imaging means is moved based on the success or failure of recognition, and then the imaging means is moved until decoding is successful.

  The determination by the recognizing means 5 can be realized by binarizing the multi-value information stored as the image information and then checking whether there is a characteristic pattern possessed by various optical information. As a specific example of the recognition process, one described in detail as a code cutout means in JP-A-10-63771 is known. Note that the determination of whether or not the optical information 1 exists in this way is referred to as recognition.

  Then, after successful recognition, the decoding unit 6 analyzes the image data of the optical information 1 stored in the image storage unit 4 and converts the optical information 1 into numerical data.

  The moving means 7 is controlled based on the outputs of the recognizing means 5 and the decoding means 6, and the position of the imaging means 2 is changed by the moving means 7. The movement of the imaging means 2 by the moving means 7 will be described in detail later.

  If the recognition means 5 determines that the optical information 1 does not exist, the recognition means 5 controls the moving means 7 to change the position of the imaging means 2 and then the newly obtained conversion means 3. Is stored in the image storage means 4 as image information. The recognizing means 5 checks again the presence or absence of the optical information 1 from the information in the image storage means 4. This process is repeated until optical information 1 is detected.

  If the decoding by the decoding means 6 fails, the decoding means 6 controls the moving means 7 to change the position of the imaging means 2, and then the newly obtained output of the converting means 3 is stored in the image. The information is stored in the means 4 as image information. The recognizing means 5 checks again the presence or absence of the optical information 1 from the information in the image storage means 4. If the recognition is successful, the decoding unit 6 analyzes the image data of the optical information 1 stored in the image storage unit 4 and converts the optical information 1 into numerical data. This process is repeated until the optical information 1 is successfully decoded.

  FIG. 2 is a block diagram of a configuration example of the optical information reading apparatus of the present invention.

  The image storage means 4, the recognition means 5, and the decoding means 6 shown in FIG. 1 are realized by the hardware and software of the computer 8 shown in FIG. The computer 8 includes a CPU 10, a memory 11, an interface 9, and the like. The image storage unit 4 is configured by storing the output of the conversion unit 3 in the memory 11, and the program stored in the memory 11 is also stored. The recognition means 5 and the decoding means 6 are realized by the processing.

  The moving means 7 includes a motor controller 12, a motor 13, a ball screw 14, a lens holder 15, and a detection switch 16. The computer 8 outputs pulses necessary for rotating the motor 13 by a predetermined angle to the motor controller 12. The motor 13 rotates according to the input pulse number to rotate the ball screw 14. The lens holder 15 moves on the ball screw 14 when the ball screw 14 rotates. The imaging means 2 is fixed to the lens holder 15, and the imaging means 2 is moved by the movement of the lens holder 15.

  The detection switch 16 may be provided at either the movement limit position of the imaging unit 2 on the side close to the conversion unit 3 or the movement limit position of the imaging unit 2 on the side far from the conversion unit 3. This is a reference position for the operation of the imaging means 2.

  The trigger switch 17 is an input means for an operator who uses the apparatus to request the computer 8 to start reading the optical information 1.

  The input / output device 18 is configured by a screen, a communication device, and the like, and is a device for displaying read information and communicating with other devices.

  FIG. 3 is a flowchart showing an operation example of the reading process of the optical information reading apparatus.

  In general, after the power is turned on, return to origin is performed in step 100. In this return to origin, the lens holder 15 is moved in the direction in which the detection switch 16 exists, and the lens holder 15 is moved to this position with the position where the detection switch 16 is operated as the operation reference position. In this case, the operation reference position may be the origin.

  Next, step 101 is executed to check the occurrence of a read request such as a trigger switch 17 being pressed. If there is no reading request, step 102 is executed to check whether or not the reading operation is interrupted. If it is continued, step 101 is executed again. If it is interrupted, the reading process is terminated.

  On the other hand, if there is a read request, step 103 is executed to capture image information into the image storage means 4. In step 104, the image information stored in the image storage means 4 is binarized, and the presence of the characteristic portion of the optical information 1 is checked. If it is recognized in step 105 that the optical information 1 is present, the process proceeds to step 106, and if it is not recognized, the process proceeds to step 109.

  In step 106, which is a process after recognizing the optical information 1, the optical information 1 is decoded. In step 107, it is determined whether the decoding of the optical information 1 is successful or unsuccessful. If the decoding is successful, step 108 is executed, and the information read to the external device is output by screen output or communication. Etc. are executed. If decoding fails, the process proceeds to step 109.

  In step 109, which is processing after recognition or decoding has failed, it is determined whether a reading processing interruption condition has occurred. As an example of this interruption processing, there is a case where the trigger switch 17 that requests reading is released or a predetermined time has elapsed. If the interruption condition is satisfied, step 108 is executed. In this case, information indicating that reading could not be performed may be output, but usually nothing is displayed. If the interruption condition is not satisfied, step 110 is executed.

  In step 110, the position of the imaging means 2 is moved by controlling the motor 13 and moving the lens holder 15. Thereafter, the process proceeds to step 103 again, and the above-described processing is executed. The moving process in step 110 will be described in detail later.

  By performing the above processing, the imaging means 2 can be moved to a position where the optical information 1 can be read appropriately, and the optical information 1 can be decoded.

  Next, an example of moving the imaging means 2 will be described with reference to FIGS.

  FIG. 4 is a block diagram of a configuration example of an optical information reading apparatus showing an example of movement control of the imaging means 2.

  The image storage means 4, the recognition means 5 and the decoding means 6 shown in FIG. 1 are constituted by a computer 8, and this computer 8 includes a first storage means 19, a second storage means 20, and a third storage which will be described later. The storage means 21 and the position counter 22 are controlled.

  When moving the position of the imaging means 2, moving from the origin position toward the movement limit position on the conversion means 3 side in the negative direction, moving toward the movement limit position on the side away from the conversion means 3 A positive direction is set, and the number of pulses indicating the amount of movement is added to the position counter 22 after adding a positive / negative sign according to each direction. Further, the position of the imaging means 2 can be known from the count value of the counter 22.

  A case will be described in which the first storage means 19 stores the value of the position counter of the imaging means 2 when the previous decoding was successful, and performs the reading process. The focal length to the same type of optical information when reading optical information continuously is considered to be almost unchanged. In this case, the amount of movement of the imaging means for focus adjustment is minimized and the reading is completed. In order to minimize the time, a first storage means 19 for storing the position of the imaging means that has been decoded last time is provided, and the imaging means is first moved to the position of the imaging means that has been previously decoded. Start recognition.

  Therefore, in the present embodiment, the reading process is performed after the imaging unit 2 is moved to the position of the imaging unit 2 that was previously recognized. The optical information 1 that is normally read is often the same type of information, and therefore there is almost no change in the focal position. In this case, the optical information 1 exists in a shorter time when the recognition process is performed from the position where the previous decoding was successful than when the presence or absence of the optical information 1 is checked while sequentially performing the recognition process from the origin position. Can be detected.

  Furthermore, regarding the reading of optical information, whether or not it can be recognized first depends on whether optical information that is read at a relatively long distance is often handled or optical information that is read at a short distance is often handled. By determining the moving direction of the imaging means for this purpose, it becomes possible to read optical information in a shorter time. For this reason, the second storage unit stores whether the initial movement direction of the imaging unit is toward the movement limit position on the side closer to the conversion unit or the movement limit position on the side far from the conversion unit. The storage means is provided, and the movement is started to the minimum in the moving direction determined here.

  Further, the second storage means 20 has the first moving direction of the imaging means 2 toward the movement limit position closer to the conversion means 3 side or the movement limit position on the side away from the conversion means 3. It can be recognized first depending on whether the optical information 1 that is read at a relatively long distance is often handled or the optical information 1 that is read at a short distance is often handled. It is possible to read the optical information 1 in a shorter time by setting the direction to check whether or not.

  Similarly, depending on whether optical information that is read at a relatively long distance or optical information that is read at a short distance is handled, it is possible to shorten the optical time in a shorter time by limiting the range of whether or not recognition is possible. Target information can be read. For this reason, a third storage means for storing the moving range of the image forming means is provided, and the reciprocating movement is made within the moving range determined here.

  The third storage means 21 stores the moving range of the imaging means 2, and depending on whether the optical information 1 read at a relatively long distance or the optical information 1 read at a short distance is handled. The range for checking whether or not recognition is possible is limited so that optical information can be read in a shorter time.

  FIG. 5 is a flowchart showing an example of movement control by the first storage unit 19.

  After the power is turned on, step 200 is executed to move the imaging means 2 to the origin position. At this time, the value of the position counter 22 is set to zero. Thereafter, step 201 is executed, and a pulse corresponding to the value of the position where the previous decoding was successful stored in the first storage means 19 is output to the moving means 7 to move the imaging means 2 to that position.

  In step 202, the processing after step 101 in FIG. 3 is executed, and the data possessed by the optical information 1 is output.

  FIG. 6 is a flowchart showing an example of the movement control by the second storage means 20, and details the movement processing in step 110 of FIG. 3 described above.

  When the movement process is started, step 301 is first executed to check whether the imaging means 2 is at the movement limit position. Specifically, the value of the position counter 22 is checked to determine whether or not the imaging unit 2 is in the movable range provided by the moving unit 7. When the imaging means 2 is not at the movement limit position, the process proceeds to step 302, and when it is at the movement limit position, the process proceeds to step 305.

  In step 302, it is determined whether or not the current movement is the first movement after a reading request is made. If it is the first movement, the process proceeds to step 303, and if it is not the first movement, the process proceeds to step 304.

  In step 303, the imaging means 2 is moved by outputting a predetermined pulse to the moving means 7 so as to move in the moving direction stored in the second storage means 20.

  In step 304, the movement means 7 is controlled so as to move in the same direction as the previous movement because it is not the first movement and the movement has not reached the movement limit position.

  In step 305, since the current position is at the movement limit, the moving means 7 is controlled to move in the direction opposite to the previous movement direction.

  In step 306, the amount of movement is added to the position counter 22 with a positive or negative sign.

  By performing such movement control, the image forming means that focuses on each of them depending on whether optical information read at a relatively long distance is often handled or optical information read at a short distance is often handled. 2 is preferentially checked by the recognition means 5 and the decoding means 6, and the reading process can be completed in a relatively short time.

  FIG. 7 is a flowchart showing an example of movement control by the third storage unit 21.

  After returning to the origin, the imaging means 2 is moved to a predetermined position within the movement range stored in the third storage means 21.

  In the subsequent movement process, step 401 is executed to check whether or not the position of the imaging means 2 is the limit position of the movement range stored in the third storage means 21, and if it is not the limit position of the movement range. Step 402 is executed, and if it is the limit position of the movement range, step 403 is executed.

  In step 402, the moving means 7 is controlled so that the imaging means 2 moves in the same movement direction as the previous time. In step 403, the moving means 7 is controlled so that the imaging means 2 moves in the direction opposite to the previous movement.

  By performing such movement control, there is an imaging means 2 that is focused on depending on whether optical information read at a relatively long distance is handled or optical information read at a short distance is handled. The power position is preferentially checked by the recognition means 5 and the decoding means 6 and the reading process can be completed in a relatively short time.

  The optical information reading apparatus of the present invention can adjust the focal position in order to read the difference in the code size and resolution of the optical information with one optical information reading apparatus, and the focal position is automatically adjusted. The present invention is industrially useful as an optical information reading device having a simple configuration that does not have a device such as a sensor for measuring a distance for adjustment.

Block diagram of the optical information reader of the present invention The block diagram of the structural example of the optical information reader of this invention The flowchart which shows the operation example of the reading process of the optical information reader of this invention. Block diagram of a configuration example of an optical information reading device showing an example of movement control of the imaging means The flowchart which shows an example of the movement control by a 1st memory | storage means The flowchart which shows an example of the movement control by a 2nd memory | storage means The flowchart which shows an example of the movement control by a 3rd memory | storage means Block diagram showing the configuration of a conventional optical information reader

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical information 2 Imaging means 3 Conversion means 4 Image storage means 5 Recognition means 6 Decoding means 7 Moving means 8 Computer 9 Interface 10 CPU
DESCRIPTION OF SYMBOLS 11 Memory 12 Motor controller 13 Motor 14 Ball screw 15 Lens holder 16 Detection switch 17 Trigger switch 18 Input / output device 19 1st memory | storage means 20 2nd memory | storage means 21 3rd memory | storage means

Claims (4)

Imaging means for imaging light reflected from optical information, conversion means for receiving light imaged by the imaging means and converting it into an image signal, image storage means for storing the image signal, Recognizing means for recognizing the presence of optical information from the image signal; decoding means for decoding optical information from the image signal; and the imaging when the recognizing means cannot recognize the optical information. An optical information reader comprising moving means for moving the position of the means. 2. The optical information reader according to claim 1, further comprising: a first storage unit that stores a position of the imaging unit that has been decoded last time, wherein the position of the imaging unit that has been previously decoded is a first recognition position. Second storage means for storing whether the initial moving direction of the imaging means is toward the movement limit position on the conversion means side or the movement limit position on the side away from the conversion means. The optical information reader according to claim 1. 2. The optical information reader according to claim 1, further comprising third storage means for storing a moving range of the image forming means.

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