JP2006277478A - Optical information reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information reader for intuitively notifying a user of a state in or out of focus without impairing reading work efficiency. <P>SOLUTION: The optical information reader has a guide light module 4 irradiating guide light showing a readable region, estimates a focus state based on information obtained from a distance sensor 5 or the like, and irradiates guide light almost continuously while controlling the output of guide light according to the estimated focus state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical information reading device that reads optical information from a reading target on which optical information such as a barcode or a two-dimensional code is described, and in particular, a non-contact method capable of reading a reading target at a position away from a reading port. The present invention relates to an optical information reader.

  In recent years, a matrix type two-dimensional code displayed in a vertical and horizontal mosaic pattern, which can store a large amount of information at a higher density than a barcode, is utilized mainly in production management in factories. In the future, its use is expanding in fields such as transportation and distribution, and when reading a two-dimensional code affixed to a package in a warehouse, from a distance of about 10 cm to a distance of about 50 cm. It is desirable that it can be read.

  In this way, in a non-contact type optical information reading apparatus having an image sensor that reads a two-dimensional code at a distant position, the position within a readable area of a reading target is larger than that of a contact type optical information reading apparatus. Matching becomes difficult. Therefore, it is considered to irradiate the guide light indicating the readable area, and irradiate the guide light with the shape corresponding to the readable range using the LD (semiconductor laser) as the light source, and the readable range for the user. Many optical information readers have been developed.

At the same time, in a non-contact type optical information reading apparatus using a single focus lens having such an image sensor, it is difficult to focus, so the user is notified whether the focus is in focus. It is desirable. As this notification method, for example, a method for notifying the in-focus state based on the number of times of light emission of the notification LED, the tone color and the number of occurrences of a beep sound, a voice guide, the number of times of light emission of guide light, etc. has been proposed (for example, Patent Document 1 reference).
Japanese Patent Laid-Open No. 2001-84452 (2nd page, FIG. 1)

  However, regarding the notification method described in this publication, in the notification method using sound, it is assumed that the user cannot hear the notification sound well and does not function in an environment where the ambient noise is large.

In the notification method using the LED, it is assumed that the user needs to gaze at the LED arranged on the reading device main body, and the line of sight must be removed from the reading target.
In addition, in the notification method based on the number of times the guide light is emitted, it is necessary to turn off the guide light for a time that allows human eyes to recognize that the light has been turned off for the set number of times of light emission. There is a concern that the degree will increase and the efficiency of the reading operation will decrease.

  Therefore, the present invention irradiates guide light indicating an area that can be read by the optical information reader substantially continuously, and controls the output of the guide light according to the focus state, without impairing the reading work efficiency. It is an object of the present invention to provide an optical information reading apparatus that intuitively notifies a user whether or not a focus is achieved.

  In order to achieve the above object, an optical information reader provided in the present invention forms an image of reflected light from optical information and captures it as an image, and guide light for referring to the readable range of the image sensor. Guide light irradiating means for irradiating, a focus state estimating means for estimating a focus state of the image captured by the image sensor, and the guide light from the guide light irradiating means based on information from the focus state estimating means. A guide light control unit for controlling the output. With this configuration, the output of the guide light is changed depending on the focus state.

  As described above, in the optical information reading apparatus having the guide light irradiation function indicating the readable area, the present invention intuitively changes the focus state to the user by changing the output of the guide light according to the focus state. Can be shown and focused easily.

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

(Embodiment 1)
FIG. 1 is a diagram illustrating an external configuration example of the optical information reading apparatus 1 according to the first embodiment. An optical module 2 is built in the optical information reader 1, and the optical module 2 includes an imaging lens 3, a guide light module 4, and a distance sensor 5.

  The guide light irradiation pattern 4a irradiated from the guide light module 4 serving as the guide light irradiation means is, for example, a key bracket positioned at a corner of the readable area so that the readable area of the CMOS sensor 6 serving as the image sensor is known. It consists of a shape and a cross in the center. At this time, the optical axis of the guide light and the optical axis of the imaging system do not coincide with each other, exist in the same plane, and form an angle so as to substantially intersect near the focal position of the imaging system.

  The operation and action of the optical information reading apparatus 1 configured as described above will be described with reference to FIGS. FIG. 2 is a block diagram of a portion related to the guide light control of the optical information reading apparatus 1 according to the present invention, and FIG. 3 is a flowchart showing a system operation related to the guide light control.

  In starting reading, the user presses the trigger key 7 (step S1). When the trigger key 7 is pressed, the CPU 8 obtains distance information from the CMOS sensor 6 to the two-dimensional code from the distance sensor 5 such as an infrared distance sensor (step S2), and at the position where the focal position and the two-dimensional code are located. The deviation is calculated, the focus state is estimated, and the guide light output is determined according to the deviation width (step S3).

  At this time, the focal position is known from the setting information of the imaging optical system. Regarding the determination of the guide light output, for example, as shown in FIG. 4, when the maximum output of the light source to be set is 100, the output is 100 for a range in which the deviation from the focal position is sufficiently small and can be read satisfactorily. A method is conceivable in which the output is gradually decreased as the deviation is out of the range, and the output is kept constant at a low output such as 20 for a range where the deviation width is larger than a certain value and difficult to read.

  The output value of the guide light determined in this way is output to the guide light control unit 9, and the guide light control unit 9 drives the guide light module 4 so that the irradiation light having the determined output is emitted, and is two-dimensional. The cord is irradiated with guide light (step S4).

  Next, an image is captured by the CMOS sensor 6 (step S5), code information is detected from the image sent to the code information detection unit 10 and captured, and converted into an electrical signal (step S6). The code information converted into the electrical signal is sent to the CPU 8 and is subjected to decoding processing (step S7), and it is determined whether or not the information has been correctly acquired (step S8).

  If the information can be acquired, the user is notified of the completion of reading by a beep sound or the like (step S10). If the information acquisition is impossible, there is no notification of completion of reading, so the user continues the reading operation, moves the reading device with reference to the output of the guide light, and searches for the focal position. The distance between the dimension codes is adjusted (step 9).

  Then, the distance information is obtained again by the distance sensor 5 at the moved position, and the operation after step S2 is repeated until the code information acquisition is successful and the reading completion notification is made. Here, it is assumed that the operations included in the loop constituted by steps S2 to S9 in FIG. 3 are performed in a very short time and do not affect the operability of the user.

  In the above example, the setting is such that the output of the guide light increases as the position of the two-dimensional code is closer to the focal position, and the output of the guide light decreases as the position is farther away. It may be set such that the guide high output increases as the position becomes far from the focal position, and the guide light output decreases as the position becomes closer, and further, ON / OFF may be used properly without being limited to output adjustment. Since the irradiation light for reading the two-dimensional code is irradiated from the illumination LED with the guide light turned off once, the magnitude of the output of the guide light does not affect the reading performance.

  Further, if the pattern indicating the cross shape located at the center is output only in the case of representing the focused state in the irradiation pattern 4a of the guide light, the user can more easily recognize the focus state.

  Furthermore, if the color of the pattern indicating the cross located at the center is changed depending on whether or not it is in focus, the user can more easily focus on the optical information.

(Embodiment 2)
As a second embodiment, a case where the distance sensor 5 is not provided will be described. The optical information reading device of the second embodiment has the same external configuration as that of the first embodiment shown in FIG. 1 except that the distance sensor 5 is not provided, and the optical module 2 is built in the optical module. 2 includes an imaging lens 3 and a guide light module 4.

  The guide light irradiation pattern 4a irradiated from the guide light module 4 serving as the guide light irradiation means is, for example, a key bracket positioned at a corner of the readable area so that the readable area of the CMOS sensor 6 serving as the image sensor is known. It consists of a shape and a cross in the center. At this time, the optical axis of the guide light and the optical axis of the imaging system do not coincide with each other, exist in the same plane, and form an angle so as to substantially intersect near the focal position of the imaging system.

  The operation and action of the optical information reading apparatus configured as described above will be described with reference to FIGS. FIG. 5 shows a block diagram of a portion related to guide light control of the optical information reading apparatus 1 according to the present invention, and FIG. 6 is a flowchart showing a system operation related to guide light control.

  In starting reading, the user presses the trigger key 7 (step S11). When the trigger key 7 is pressed, an image is captured from the CMOS sensor 6 (step S12), code information is detected by the code information detection unit 10 of the information processing unit, and is converted into an electrical signal (step S13).

  The code information converted into the electric signal is sent to the CPU 8 and is subjected to decoding processing (step S14), and it is determined whether or not the information has been correctly acquired (step S15). If the information can be acquired, the user is notified of the completion of reading by a beep sound or the like (step S21). If the information acquisition is impossible, the signal level detection unit 11 of the signal processing unit detects the signal level (step S16), and the detected signal level information is output to the CPU 8.

  The CPU 8 estimates the focus state based on the signal level information sent from the signal level detection unit 11 (step S17). For this estimation, for example, contrast information obtained from signal level information can be used.

  That is, a high contrast can be obtained between the black portion and the white portion of the matrix constituting the two-dimensional code in a focused state, but a high contrast cannot be obtained in a defocused state. Therefore, it can be estimated whether or not the image is in focus based on the magnitude of the contrast value.

  The contrast value here is actually defined as the difference in signal level when detecting the white part and black part of the matrix constituting the two-dimensional code, that is, the difference in voltage value (ΔV). The value is synonymous with this voltage value difference. The CPU 8 determines how much the focus is deviated based on the contrast value obtained above, and determines a guide light output corresponding to the degree (step S18).

  A specific determination method will be described with reference to FIGS. FIG. 7A shows an example of the signal level V at the position detected by the signal level detection unit 11 in a focused state, and FIG. 7B shows the position at the position detected with the focus shifted. An example of the signal level V is shown.

  In other words, a clear signal level difference is obtained between the white portion and the black portion of the matrix constituting the two-dimensional code in the focused state (ΔV1), but white in the out-of-focus state. When the image of the part and the image of the black part are mixed, the signal level is reduced, and a clear difference in height cannot be obtained (ΔV2).

  Next, the CPU 8 determines the guide light output based on the level difference ΔV of the signal level, that is, the contrast value. With respect to the determination of the guide light output, for example, as shown in FIG. 8, when the maximum guide light output to be set is 100, the output is set to 100 for a sufficiently large and satisfactorily readable range such as ΔV1, A method is conceivable in which the output is gradually decreased as the contrast value is decreased, and the output is kept constant at a low output such as 20 for a range in which the contrast value is smaller than a certain value and difficult to read, such as the contrast ΔV2.

  The guide light output value determined in this way is output to the guide light control unit 9, and the guide light control unit 9 drives the guide light module 4 so that the irradiation light having the determined output is emitted, and the two-dimensional code. Is irradiated with guide light (step S19).

  Since it is impossible to acquire information in step S15, the user who has not been notified of the completion of reading continues the reading operation, and moves the reading device with reference to the output of the guide light to search for the focal position. Then, the distance between the apparatus and the reading object is adjusted (step S20).

  Then, at the moved position, the image is captured again by the CMOS sensor 6, and the operations after step S12 are repeated until the code information acquisition is successful and the reading completion notification is made. Here, it is assumed that the operations included in the loop constituted by steps S12 to S20 in FIG. 6 are performed in a very short time and do not affect the operability of the user.

  In the above example, the guide light output increases as the contrast value increases, and the guide light output decreases as the contrast value decreases. However, this is not the case. Conversely, the guide high output increases as the contrast value decreases. The guide light output may be set to be smaller as the value is larger, and further, ON / OFF may be properly used without being limited to the output adjustment.

  As described above, according to the present invention, in the optical information reading apparatus having the guide light irradiation function indicating the readable area, the user can focus on the user by changing the output of the guide light according to the focus state. Since it is possible to intuitively indicate whether or not they match, it is particularly effective in a non-contact type optical information reading apparatus capable of reading a reading object at a position away from the reading port.

1 is an external configuration diagram of an optical information reading device according to Embodiment 1 of the present invention. FIG. 2 is a block diagram illustrating a configuration example of an optical information reading device according to the first embodiment. A flowchart showing a reading operation of the optical information reading apparatus in the first embodiment. The figure showing an example of the guide light output determination reference | standard in the same Embodiment 1 The block diagram showing the example of a structure of the optical information reader in Embodiment 2 of this invention. A flowchart showing a reading operation of the optical information reading apparatus in the second embodiment. (A) The figure showing an example of the detection signal level of the state in focus in the same Embodiment 2 (b) The figure showing an example of the detection signal level in the state of being out of focus in the same Embodiment 2. The figure showing an example of the guide light output determination reference | standard in Embodiment 2

Explanation of symbols

4 Guide Light Module 4a Guide Light Irradiation Pattern 5 Distance Sensor 6 CMOS Sensor 8 CPU
9 Guide light controller 11 Signal level detector

Claims (6)

An imaging device that forms an image of reflected light from optical information and captures it as an image, guide light irradiation means for irradiating guide light for referring to a readable range of the imaging device, and a focal point of the image captured by the imaging device An optical information reading apparatus comprising: a focus state estimation unit that estimates a state; and a guide light control unit that controls an output of the guide light from the guide light irradiation unit based on information from the focus state estimation unit. An imaging element that forms an image of reflected light from optical information and captures it as an image, guide light irradiation means for irradiating guide light for referring to a readable range of the imaging element, and a distance between the imaging element and the optical information A distance detection unit that detects a focus state of the image captured by the imaging device based on an output of the distance detection unit, and a guide light based on information from the focus state estimation unit An optical information reading apparatus comprising: a guide light control unit that controls output of the guide light from the irradiation unit. The optical information reading apparatus according to claim 1, wherein the focus state estimation unit estimates a focus state of the image from contrast information of the image captured by the image sensor. The guide light emitted from the guide light irradiating means to the readable range under the control of the guide light control unit has a pattern indicating the center of the readable range, and the output from the focus state estimating means represents the in-focus state The optical information reading apparatus according to claim 1, wherein the pattern indicating the central portion is brightened as compared to a case other than the case where the in-focus state is not indicated. The guide light emitted from the guide light irradiating means to the readable range under the control of the guide light control unit has a pattern indicating the center of the readable range, and the output from the focus state estimating means represents the in-focus state 4. The optical information reading apparatus according to claim 1, wherein a pattern indicating the central portion is output only on the optical information reading apparatus. Whether the guide light emitted from the guide light irradiating means to the readable range under the control of the guide light control unit has a pattern indicating the center of the readable range, and whether the output from the focus state estimating means represents the in-focus state. The optical information reading apparatus according to claim 1, wherein the optical information reading device outputs the pattern color indicating the central portion depending on whether or not.