Optical information reading device and method for controlling the same

Abstract

To achieve an optical information reading device capable of determining whether or not a size of an information code in a visual field falls within a range suitable for reading.SOLUTION: An optical information reading device includes: an imaging unit (14) for imaging an information code (Q) including a plurality of modules; an image recognition unit (15) for decoding the information code; a distance measurement unit (11) for measuring a distance between the imaging unit and the information code when the imaging unit images the information code; a range setting unit (12) for setting a range of proper distance capable of reading the information code; and a determination unit (13) for determining whether or not the measured distance falls within the range of the proper distance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical information reader for optically reading an information code. [Background technology]

[0002] Handy optical information reading devices are used to optically read information codes such as bar codes or two-dimensional codes. Optical information reading devices are equipped with a light receiving sensor such as a CCD area sensor, an imaging optical section having an imaging lens, an illumination device such as an LED (Light Emitting Diode), etc., so that they can read the information code from a position away from the code to be read.

[0003] In an optical information reading device, when a trigger switch is operated while pointed at the information code to be read, the lighting device illuminates the information code, and the reflected light passes through the imaging optical unit and enters the light receiving sensor, where it is imaged.

[0004] Patent Document 1 discloses a technique for detecting the degree of blurring of an information code and notifying a user to read the information code at a distance that will prevent the information code from being blurred. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-089069 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned conventional techniques only take into consideration the degree of blurring of the information code, and it is possible that the information code is too small to fit within the field of view or is unreadable.

[0007] An object of one aspect of the present invention is to provide an optical information reading device capable of determining whether the size of an information code in a field of view is within a range suitable for reading. [Means for solving the problem]

[0008] In order to solve the above problems, an optical information reading device according to one embodiment of the present invention includes an imaging unit that images an information code including a plurality of light color modules and dark color modules, an image recognition unit that decodes the information code imaged by the imaging unit, a distance measurement unit that measures the distance between the imaging unit and the information code when the imaging unit images the information code, a range setting unit that sets an appropriate distance range within which the image recognition unit can read the information code, and a determination unit that determines whether the distance falls within the range.

[0009] According to the above configuration, it is possible to determine whether the information code can be decoded normally based on whether the distance to the information code is within an appropriate distance range, thereby enabling the user to efficiently read the information code.

[0010] The information processing device may further include a communication unit that communicates with an external device, the communication unit acquiring information related to the information code, and the range setting unit setting the range based on the information.

[0011] According to the above configuration, the distance range can be automatically set by acquiring information related to the information code from the external device by the communication unit.

[0012] The communication unit may obtain information regarding a first physical size of the information code and / or information regarding a second physical size of the light color module and the dark color module.

[0013] According to the above configuration, the communication unit can obtain information for appropriately setting the distance range.

[0014] The range setting unit may set a lower limit of the range based on the first size, or may set an upper limit of the range based on the second size.

[0015] According to the above configuration, the range setting unit can set how close the object is permitted to be to the information code using the first size, and can set how far the object is permitted to be from the information code using the second size.

[0016] The range setting unit may be capable of inputting information relating to the range.

[0017] According to the above configuration, the distance range can be set by user input.

[0018] The image recognition unit may obtain a first physical size of the information code and a second physical size of the light color module and the dark color module by decoding the imaged information code, and the range setting unit may set a lower limit of the range based on the first size or set an upper limit of the range based on the second size.

[0019] According to the above configuration, by reading the information code, information on the dimensions of the information code is identified, and then the distance range can be set based on the distance to the information code and the information contained in the information code. That is, the range setting unit can set how close the device can be to the information code using the first size, and can set how far the device can be away from the information code using the second size.

[0020] The image forming apparatus may further include a notification unit that notifies a user of the determination result of the determination unit.

[0021] According to the above configuration, the user can know the determination result of the determination section by the notification section, and can perform reading again.

[0022] The notification unit may provide notification according to a degree of deviation between the distance and the range.

[0023] According to the above configuration, the notification unit allows the user to know what to do to keep the distance to the information code within the distance range, so that the user can efficiently re-try reading the information code.

[0024] The range may be a range defined so that the information code falls within the field of view of the imaging unit, or a range defined so that the sizes of the light module and the dark module satisfy the required number of pixels.

[0025] According to the above configuration, it is possible to clearly determine the conditions under which an image from which an information code can be decoded can be captured.

[0026] In order to solve the above problems, a control method for an optical information reading device according to one embodiment of the present invention includes an imaging step of imaging an information code including a plurality of light color modules and dark color modules, a distance measurement step of measuring a distance to the information code when imaging the information code in the imaging step, an image recognition step of decoding the information code imaged in the imaging step, a range setting step of setting an appropriate distance range for reading the information code in the image recognition step, and a determination step of determining whether the distance falls within the range.

[0027] According to the above configuration, it is possible to determine whether the information code can be decoded normally, based on whether the distance to the information code is within an appropriate distance range. Effect of the Invention

[0028] According to one aspect of the present invention, it is possible to determine whether or not the information code can be decoded normally, based on whether or not the distance to the information code is within an appropriate distance range. [Brief description of the drawings]

[0029] [Figure 1] 1 is a block diagram showing a configuration of a main part of a handy code reader; [Diagram 2] 1 is an example of an information code. [Diagram 3] FIG. 2 is a schematic diagram showing the working distance between an information code and a handy code reader. [Figure 4] 11 is a diagram showing the relationship between the field of view of an imaging unit and an information code. FIG. [Diagram 5] 10 is a flowchart showing the flow of an operation for reading an information code by a handy code reader. [Figure 6] 10 is a flowchart showing the flow of an operation for initially reading an information code by a handy code reader. [Figure 7] 10 is a flowchart showing the flow of a normal operation of reading an information code by a handy code reader. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] [Embodiment] Hereinafter, an embodiment according to one aspect of the present invention (hereinafter, also referred to as "the present embodiment") will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0031] §1 Examples of application 1 is a block diagram showing the configuration of the main parts of a handy code reader (optical information reading device) 1. The handy code reader 1 is a portable optical information reading device that is carried by a user. When the handy code reader 1 reads an information code Q, the handy code reader 1 simultaneously measures the distance (working distance) from the handy code reader 1 to the information code Q by using a distance measuring unit 11. The handy code reader 1 autofocuses the imaging unit 14 based on the measured working distance, but as a result, the information code Q is not necessarily in a state where it can be read in the captured image.

[0032] Fig. 2 is an example of an information code Q. The information code Q is, for example, a barcode or a two-dimensional code (symbol), and Fig. 2 is an example of a two-dimensional code. The information code Q includes a plurality of light color modules Qa and dark color modules Qb. The light color modules Qa are not limited to white. The dark color modules Qb are not limited to black. In other words, it is sufficient that the dark color modules Qb are darker than the light color modules Qa and have a color difference that allows them to be distinguished from each other.

[0033] FIG. 3 is a schematic diagram showing the working distance between the information code Q and the handy code reader 1. As shown in FIG. 3, there are cases where the distance is short and the information code Q does not fall within the field of view V of the imaging unit 14 (Q1 in FIG. 3). There are also cases where the distance is long and the information code Q falls within the field of view V but is not imaged with sufficient resolution (Q2 in FIG. 3). Of course, there are also cases where the information code Q is imaged at an appropriate distance, so that the information code Q falls within the field of view V and the data contained in the information code Q can be decoded (Q3 in FIG. 3). In this way, the appropriate working distance varies depending on the physical size of the information code Q.

[0034] §2 Configuration Example (Handy Code Reader 1 Configuration) The handy code reader 1 includes a distance measurement unit 11, a range setting unit 12, a determination unit 13, an imaging unit 14, an image recognition unit 15, a notification unit 16, and a communication unit 17. The communication unit 17 communicates with an external device 20.

[0035] The distance measurement unit 11 measures a working distance between the imaging unit 14 (described later) and the information code Q when the imaging unit 14 captures an image of the information code Q. The distance measurement unit 11 may be a general distance measurement sensor, such as an infrared distance measurement sensor or a LiDAR (Light detection and ranging). The working distance measured by the distance measurement unit 11 is output to the range setting unit 12 and the determination unit 13.

[0036] The range setting unit 12 stores the distance range within which the handy code reader 1 can read the information code Q. In other words, the range setting unit 12 sets and stores an appropriate distance range within which the image recognition unit 15 can read the information code Q. The range setting unit 12 outputs the stored distance range to the determination unit 13. The range setting unit 12 includes a storage unit that stores the distance range, or acquires the distance range from the storage unit.

[0037] In addition, the range setting unit 12 sets the appropriate distance range based on various information. In other words, the range setting unit 12 also includes a function of changing the setting of the appropriate distance range based on the information input from the image recognition unit 15 and the working distance input from the distance measurement unit 11.

[0038] The determination unit 13 determines whether or not the working distance measured by the distance measurement unit 11 falls within the distance range stored in the range setting unit 12. The determination unit 13 outputs the result of the determination to the notification unit 16.

[0039] The imaging unit 14 is composed of a light receiving sensor such as a CCD area sensor and an imaging optical unit having an imaging lens. The imaging unit 14 captures an image of the information code Q. The imaging optical unit has a function of adjusting the focus. The imaging unit 14 outputs the captured image to the image recognition unit 15.

[0040] The image recognition unit 15 processes the input image and decodes the information code Q contained in the image. The image recognition unit 15 outputs the decoded result to the range setting unit 12 and the notification unit 16.

[0041] The notification unit 16 notifies the user based on the input result of the determination by the determination unit 13 or the result of decoding by the image recognition unit 15. The notification unit 16 may be a buzzer, an LED, or the like. The notification form of the notification unit 16 is not limited to one type and may take various forms.

[0042] The communication unit 17 is a functional block for the handy code reader 1 to communicate with the external device 20. The communication unit 17 outputs information acquired through communication to the range setting unit 12. The information is related to the information code Q.

[0043] (External device 20) The external device 20 is a device that operates in cooperation with the handy code reader 1. The external device 20 may be a laser marker, a printer, a print verification machine, a PLC (Programmable Logic Controller), etc. In other words, the external device 20 may be any device that can output the physical size of the information code Q and the physical sizes of the light color module Qa and the dark color module Qb to the communication unit 17.

[0044] (Field of view V and information code Q) 4 is a diagram showing the relationship between the field of view V of the imaging unit 14 and the information code Q. When the imaging unit 14 is an area camera, the captured image is a rectangle with a width Wp [pixels] and a height Hp [pixels]. By knowing the working distance, it is possible to determine from the optical characteristics of the imaging unit 14 that the physical size of the field of view V is a rectangle with a width of approximately Ws [mm] and a height of approximately Hs [mm]. The physical size of the field of view V is directly proportional to the working distance.

[0045] On the other hand, if the information code Q is a two-dimensional code, it is a pattern with a width Wc [mm] and a height Hc [mm]. The light color module Qa and the dark color module Qb that compose the information code Q are squares with a side length L [mm].

[0046] When the image capturing unit 14 captures the information code Q, the light color module Qa and the dark color module Qb are each captured as a collection of several pixels. For example, in FIG. 4, the dark color module Qb is captured as a square with six pixels on each side. The number of pixels on each side is assumed to be N. The number of pixels on each side, N, is negatively proportional to the working distance.

[0047] (Distance range) In order for the image recognition unit 15 to correctly decode the information code Q, it is necessary that Ws ≧ Wc and Hs ≧ Hc are satisfied. In other words, the physical size of the information code Q must fit within the physical size of the field of view V. As a result, the maximum distance WDmin that the handy code reader 1 can approach to the information code Q is determined.

[0048] Furthermore, in order for the image recognition unit 15 to correctly decode the information code Q, the number of pixels N on one side of the light color module Qa and the dark color module Qb must be equal to or greater than a predetermined number. By moving the handy code reader 1 away from the information code Q, the number of pixels N becomes smaller, and as a result, the maximum distance WDmax that the handy code reader 1 can be moved away from the information code Q is determined.

[0049] The range setting unit 12 sets the distance range based on the information acquired by the communication unit 17. The appropriate distance range stored in the range setting unit 12 is set as WDmin≦working distance at which the information code Q can be read normally≦WDmax. In other words, the distance range is a range specified so that the information code Q falls within the field of view V of the imaging unit 14, or a range specified so that the sizes of the light color module Qa and the dark color module Qb satisfy the condition of the required number of pixels.

[0050] §3 Example of operation Fig. 5 is a flowchart showing the flow of the operation of reading the information code Q by the handy code reader 1. Fig. 6 is a flowchart showing the flow of the operation of the handy code reader 1 for the first time reading the information code Q. Fig. 7 is a flowchart showing the flow of the operation of the handy code reader 1 for normal reading of the information code Q. Note that reading the information code Q consists of three steps: capturing an image of the information code Q, processing the captured image, and decoding the result of image processing.

[0051] The handy code reader 1 judges whether a readable distance range is stored (set) in the range setting unit 12 (S11). If a readable distance range is not stored in the range setting unit 12 (No in S11), an initial reading is performed (S20). On the other hand, if a readable distance range is stored in the range setting unit 12 (Yes in S11), a normal reading is performed (S30).

[0052] The distance range stored in the range setting unit 12 can be reset (initialized) by a specific operation. For example, this can be done by pressing a reset button provided on the handy code reader 1, or by reading a dedicated reset code as the information code Q. These user operations cause the range setting unit 12 to reset the distance range, so the reading immediately after the reset is the first reading.

[0053] In addition to reading the information code Q, in the initial reading, a process is performed to set an appropriate distance range as the working distance in the range setting unit 12. In normal reading, when reading the information code Q, the working distance is measured based on the distance range stored in the range setting unit 12, and a determination is made as to whether or not the working distance allows normal reading, and the user is notified.

[0054] (First read) The first reading will be described. In response to a trigger operation by the user, the imaging unit 14 reads the information code Q (S21). The distance measurement unit 11 measures the working distance from the handy code reader 1 to the information code Q (S22).

[0055] The image recognition unit 15 processes the image of the captured information code Q and decodes it (S23). At this time, the image recognition unit 15 acquires information on the first physical size of the information code Q and information on the second physical sizes of the light color module Qa and the dark color module Qb, which are included in the information code Q (S24). Note that these sizes are not limited to the data included in the information code Q as a result of decoding the information code Q. For example, these values ​​may be derived by reverse calculation from the working distance measured in S22, the number of pixels of the information code Q recognized by the image recognition unit 15, and information on the number of pixels of the light color module Qa and the dark color module Qb.

[0056] The range setting unit 12 sets the distance range based on the result of reading the information code Q by the imaging unit 14 and decoding it by the image recognition unit 15. That is, the range setting unit 12 stores the distance range within which the handy code reader 1 can properly read the information code Q from information on the first physical size of the information code Q and information on the second physical sizes of the light color module Qa and the dark color module Qb (S25).

[0057] (Normal read) Normal reading will now be described. In response to a trigger operation by the user, the imaging unit 14 reads the information code Q (S31). The distance measurement unit 11 measures the working distance from the handy code reader 1 to the information code Q (S32).

[0058] The determination unit 13 determines whether the working distance is within the range of distances at which the information code Q can be read (S33). If the working distance is not within the range of distances (No in S33), the normal reading process ends. Note that the notification unit 16 may provide a notification.

[0059] If the working distance is within the distance range (Yes in S33), the image recognition unit 15 performs image processing on the information code Q and decodes it (S34). The image recognition unit 15 determines whether the information code Q has been successfully decoded (S35). If the information code Q has been successfully decoded (Yes in S35), the normal reading process ends.

[0060] If the decoding of the information code Q has failed (No in S35), the image recognition unit 15 determines whether or not the information code Q has been partially decoded (S36).

[0061] If the information code Q can be decoded even partially (Yes in S36), the image recognition unit 15 considers that the quality of the information code Q may be poor, and causes the notification unit 16 to notify the user of the possibility that the quality is poor (S37).

[0062] If the information code Q cannot be decoded even partially (No in S36), the image recognition unit 15 takes into consideration the possibility that the information code Q is not present in the field of view, and the notification unit 16 notifies the user of the possibility that the information code Q is not present in the field of view (S38).

[0063] (Operation of the notification unit 16) As described above, the notification unit 16 may notify that the quality of the information code Q may be poor, or may notify that the information code Q may not be present in the field of view V. The contents of these two types of notifications may be different.

[0064] Furthermore, the determination unit 13 may notify the notification unit 16 of whether the working distance falls within the distance range, so that the notification unit 16 notifies whether the working distance falls within the distance range. If the working distance does not fall within the distance range, the notification content may be changed depending on whether the working distance is close or far. In other words, the notification unit 16 issues a notification according to the degree of deviation between the working distance and the distance range.

[0065] Regarding the content of the notification, if the notification unit 16 is a buzzer, the pitch of the sound, the number of times the buzzer sounds, and the duration may be changed. If the notification unit 16 is an LED, the lighting color, the lighting duration, and the lighting pattern may be changed.

[0066] (Operation of communication unit 17) The communication unit 17 communicates with the external device 20 to acquire the first physical size of the information code Q and the second physical sizes of the light color module Qa and the dark color module Qb. The information acquired by the communication unit 17 may be either the first size or the second size. In addition to this information, the range setting unit 12 sets an appropriate distance range based on the relationship between the working distance and the field of view V that is known based on the mechanical configuration of the imaging unit 14.

[0067] The communication unit 17 may transmit the determination result of the determination unit 13 to an external device 20 (for example, a PLC or the like).

[0068] That is, the range setting unit 12 determines, from the first physical size of the information code Q, the limit distance WDmin (the lower limit of the distance range) by which the handy code reader 1 can be brought closer to the information code Q. The range setting unit 12 determines, from the second physical size of the light color module Qa and the dark color module Qb, the limit distance WDmax (the upper limit of the distance range) by which the handy code reader 1 can be moved away from the information code Q. Note that the range setting unit 12 may only set either the limit distance WDmin or the limit distance WDmax.

[0069] Then, the range setting unit 12 sets the appropriate distance range as WDmin≦the working distance at which the information code Q can be read normally≦WDmax.

[0070] §4 Action and effect Even if the size of the information code Q is not constant but differs for each reading target, it is possible to determine whether the working distance is within the range of distances stored in the range setting unit 12. Therefore, the user can use the handy code reader 1 at an appropriate working distance, and can efficiently read the information code Q.

[0071] In addition, even if the information code Q cannot be read or the working distance is not within the range, the user can be notified of the details, so that the user can easily take appropriate action. Therefore, the information code Q can be read efficiently.

[0072] [Modifications] (Setting distance range by pixel ratio) In the embodiment, the distance range is set based on the first physical size of the information code Q and the second physical sizes of the light color module Qa and the dark color module Qb, but is not limited to this.

[0073] For example, the coefficient for the maximum number of pixels of the information code Q imaged in the field of view V that fits into a rectangle of width Wp and height Hp can be calculated, and the coefficient can be multiplied by the current working distance to calculate the maximum distance WDmin that the handy code reader 1 can approach the information code Q.

[0074] In addition, a coefficient may be calculated from the current value of the number of pixels N of the light module Qa and the dark module Qb and the number of pixels required to read the light module Qa and the dark module Qb, and the coefficient may be multiplied by the current working distance to calculate the maximum distance WDmax that the handy code reader 1 can be moved away from the information code Q.

[0075] That is, in the embodiment, the distance range was determined based on the first and second physical sizes, but the appropriate distance range may also be determined and set based on the ratio between the number of pixels in the captured image and the condition that the number of pixels must satisfy.

[0076] (Manual setting of distance range) In the embodiment, the information code Q is read, and then the first physical size of the information code Q and the second physical sizes of the light module Qa and the dark module Qb are obtained, and the distance range is automatically set, but this is not limited to the above.

[0077] For example, the handy code reader 1 may be connected to a personal computer, and the first size or the second size may be set by the user through dedicated setting software, or the distance range may be set directly.

[0078] The first size or the second size may be set by reading a dedicated setting information code. Note that the dedicated setting information code that is read at this time is not limited to a two-dimensional code and may be a bar code.

[0079] That is, information on the distance range can be input to range setting unit 12. In particular, the information on the distance range may be information that indirectly specifies the distance range, such as a first size or a second size, or may be information that directly sets the distance range.

[0080] 〔summary〕 The optical information reading device according to aspect 1 of the present invention comprises an imaging unit that images an information code including a plurality of light color modules and dark color modules, an image recognition unit that decodes the information code imaged by the imaging unit, a distance measurement unit that measures the distance between the imaging unit and the information code when the imaging unit images the information code, a range setting unit that sets an appropriate distance range within which the image recognition unit can read the information code, and a determination unit that determines whether the distance falls within the range.

[0081] An optical information reading device according to aspect 2 of the present invention may be configured in accordance with aspect 1 above, further comprising a communication unit for communicating with an external device, the communication unit acquiring information related to the information code, and the range setting unit setting the range based on the information.

[0082] An optical information reading device according to aspect 3 of the present invention may be configured in accordance with aspect 1 or 2 above, such that the communication unit acquires information regarding a first physical size of the information code, or information regarding a second physical size of the light module and the dark module.

[0083] An optical information reading device according to aspect 4 of the present invention may be configured in such a way that, in aspect 3 above, the range setting unit sets a lower limit of the range based on the first size and sets an upper limit of the range based on the second size.

[0084] The optical information reader according to a fifth aspect of the present invention is any one of the first to fourth aspects, and may be configured such that the range setting section is capable of inputting information about the range.

[0085] An optical information reading device according to aspect 6 of the present invention may be configured in any one of aspects 1 to 5 above, such that the image recognition unit obtains a first physical size of the information code and a second physical size of the light module and the dark module by decoding the imaged information code, and the range setting unit sets a lower limit of the range based on the first size or sets an upper limit of the range based on the second size.

[0086] The optical information reader according to a seventh aspect of the present invention may be configured in any one of the first to sixth aspects, further comprising a notification unit that notifies a user of the determination result of the determination unit.

[0087] An optical information reader according to an eighth aspect of the present invention may be configured in the seventh aspect as described above, wherein the notification unit issues a notification according to the degree of deviation between the distance and the range.

[0088] An optical information reading device according to aspect 9 of the present invention is any one of aspects 1 to 8 above, wherein the range is defined so that the information code falls within the field of view of the imaging unit, or the size of the light module and the dark module satisfies the required number of pixels.

[0089] A control method for an optical information reading device according to aspect 10 of the present invention includes an imaging step of imaging an information code including a plurality of light color modules and dark color modules, a distance measurement step of measuring a distance to the information code when imaging the information code in the imaging step, an image recognition step of decoding the information code imaged in the imaging step, a range setting step of setting an appropriate distance range for reading the information code in the image recognition step, and a determination step of determining whether the distance falls within the range.

[0090] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0091] 1. Handy code reader (optical information reading device) 11 Distance measurement unit 12 Range setting section 13 Judgment section 14 Imaging unit 15 Image Recognition Unit 16. Notification Department 17 Communications Department 20 External device Q Information Code Qa Light Color Module Qb Dark Module

Claims

1. an imaging unit that images an information code including a plurality of light color modules and dark color modules; an image recognition unit that decodes the information code captured by the imaging unit; a distance measurement unit that measures a distance between the imaging unit and the information code when the imaging unit captures an image of the information code; a range setting unit that sets a range of an appropriate distance at which the image recognition unit can read the information code; a determination unit that determines whether the distance is within the range.

2. A communication unit for communicating with an external device is further provided. The communication unit acquires information related to the information code, The optical information reader according to claim 1 , wherein the range setting section sets the range based on the information.

3. The optical information reader according to claim 2 , wherein the communication unit obtains information on a first physical size of the information code or information on a second physical size of the light color module and the dark color module.

4. The range setting unit is setting a lower limit of the range based on the first size; or 4. The optical information reader according to claim 3, wherein an upper limit of the range is set based on the second size.

5. The optical information reader according to claim 1 , wherein the range setting section is capable of inputting information regarding the range.

6. the image recognition unit decodes the captured information code to obtain a first physical size of the information code and second physical sizes of the light color module and the dark color module; The range setting unit is setting a lower limit of the range based on the first size; or 2. The optical information reader according to claim 1, wherein an upper limit of the range is set based on the second size.

7. The optical information reading device according to claim 1 , further comprising a notification unit that notifies a user of the determination result of the determination unit.

8. The optical information reader according to claim 7 , wherein the notification unit issues a notification according to a degree of deviation between the distance and the range.

9. An optical information reading device described in any one of claims 1 to 8, wherein the range is a range defined so that the information code falls within the field of view of the imaging unit, or a range defined so that the sizes of the light module and the dark module satisfy the required number of pixels.

10. an imaging step of imaging an information code including a plurality of light modules and dark modules; a distance measuring step of measuring a distance to the information code when the information code is imaged in the imaging step; an image recognition step of decoding the information code captured in the imaging step; a range setting step of setting an appropriate distance range for reading the information code in the image recognition step; and a determining step of determining whether the distance is within the range.

Images