Optical information reading system

Abstract

To provide a system with a compact housing, configured to enable wide-range illumination using diffused illumination, and read a workpiece which cannot be read with diffused illumination so as to expand the availability for various workpieces.SOLUTION: A fixed optical information reading apparatus 1A comprises: a translucent plate 52 which is provided at the front of a first illumination group 4a; a diffuser plate 51 which is provided at the front of a second illumination group 4b and has a larger area than the translucent plate 52; and decoding means which decodes a code image acquired by a camera by irradiating a code with light from the first illumination group 4a via the translucent plate 52 and a code image acquired by the camera by irradiating the code with light from the second illumination group 4b via the diffuser plate 51.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a stationary optical information reading device that reads a code given to a workpiece.

Background Art

[0002] Optical information reading devices include handheld ones that are held by hand and used, and stationary ones that are installed on a factory line or the like and used in a fixed state. Regarding stationary optical information reading devices, for example, they are disclosed in Patent Documents 1 and 2. The optical information reading device of Patent Document 1 includes a first illumination unit that irradiates illumination light to a workpiece through a polarizing filter, and a second illumination unit that irradiates illumination light to the workpiece without passing through a polarizing filter. Further, the optical information reading device of Patent Document 2 includes a diffuse reflection member that diffusely reflects light emitted from an illumination unit and specularly reflected on the surface of a workpiece.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when photographing a code, if the surface of the workpiece where the code is given is a mirror surface, the contrast of the code image may become low, and it may be difficult to read the code. Therefore, when photographing such a mirror-surface workpiece, diffuse illumination is used, and by irradiating the diffuse illumination to the portion that becomes the background of the code, it becomes possible to obtain a code image with high contrast.

[0005] However, in order to obtain a high-contrast code image using diffused illumination, it is necessary to irradiate diffused light on at least an area that is twice the vertical dimension and twice the horizontal dimension of the code, that is, an area four times that of the code. On the other hand, considering the installability on, for example, a factory line, there is a requirement to make the housing of the optical information reading device as small as possible. Therefore, it has been difficult to achieve both miniaturization of the housing and diffused illumination capable of irradiating a wide range.

[0006] In addition, since diffused illumination diffuses light, the contrast of the code image may become low due to insufficient light quantity, making it difficult to read the code. Therefore, if only diffused illumination is installed, the reading range of the code will be narrowed.

[0007] The present disclosure is made in view of such points, and its object is to enable wide-range illumination by diffused illumination while miniaturizing the housing, and to make it possible to read even workpieces that are difficult to read by diffused illumination with strong illumination, thereby expanding the range of workpieces that can be handled.

Means for Solving the Problem

[0008] To achieve the above object, in one aspect of the present disclosure, a stationary optical information reading device can be assumed. The optical information reading device includes a housing, a camera provided in the housing for photographing a workpiece with a code assigned thereto and obtaining a code image including the code, an illumination unit provided around the camera in the housing and having a light-emitting element for irradiating illumination to the outside, the illumination unit forming a plurality of groups, a light-transmitting plate provided on a first surface of the housing and positioned in front of the first illumination group, a diffusing plate provided on the first surface of the housing and positioned in front of the second illumination group and having a larger area than the light-transmitting plate, decoding means for decoding a code image obtained by irradiating light from the first illumination group through the light-transmitting plate onto the code and acquired by the camera and a code image obtained by irradiating light from the second illumination group through the diffusing plate onto the code and acquired by the camera.

[0009] According to this configuration, the light from the second lighting group is diffused by the diffusion plate and then irradiated onto the code. Since the diffusion plate is larger than the light-transmitting plate through which the light from the first lighting group passes, it is possible to irradiate the diffused light over a wide range, that is, for example, to irradiate the diffused light over an area four times that of the code. Thereby, even when the surface of the workpiece is a mirror surface, a high-contrast code image can be acquired by the camera.

[0010] On the other hand, the light from the first lighting group passes through the light-transmitting plate and then is irradiated onto the code. Since the amount of light when passing through the light-transmitting plate can be made larger than when passing through the diffusion plate, even for workpieces that are difficult to read with diffused illumination, sufficient light quantity can be ensured for reading, and the range of correspondence for reading various codes is expanded. Note that the light-transmitting plate and the diffusion plate can be detachably attached to the housing.

[0011] In another form, by making the distance between the center of the optical axis of the camera and the center of the optical axis of the second lighting group longer than the distance between the center of the optical axis of the camera and the center of the optical axis of the first lighting group, the diffusion plate provided in front of the second lighting group can be made larger.

[0012] In another aspect, when comparing the light-emitting elements constituting the first lighting group and the light-emitting elements constituting the second lighting group, at least one of the number, color, illumination intensity, and size is different, so more diverse illumination becomes possible, and the range of correspondence for reading is further expanded.

[0013] The lighting unit according to another aspect has a third lighting group, and since a polarizing plate is provided in front of this third lighting group, it is also possible to irradiate polarized light. The polarizing plate can be detachably attached to the housing.

[0014] In another aspect, it is possible to obtain a code image including a code by irradiating the code with direct light, diffused light, or polarized light while switching them. In this case, since the illumination information indicating which of direct light, diffused light, or polarized light was irradiated when the optical information reading device obtained the code image can be associated with the code image and displayed on the display, the user can easily confirm the illumination information.

[0015] In another aspect, a polarizing plate provided on the first surface of the housing and positioned in front of the third illumination group, a diffusion plate provided on the first surface of the housing and positioned in front of the second illumination group and having a larger area than the polarizing plate, a code image obtained by irradiating the code with light from the third illumination group through the polarizing plate and acquired by the camera, and a code image obtained by irradiating the code with light from the second illumination group through the diffusion plate and acquired by the camera, and decoding means for decoding them, can also be provided.

Advantages of the Invention

[0016] As described above, while miniaturizing the housing, it is possible to enable wide-range irradiation by diffused illumination, and moreover, it is possible to expand the corresponding range by making it possible to read even work that is difficult to read by diffused illumination.

Brief Description of the Drawings

[0017]

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Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its applications, or its uses.

[0019] FIG. 1 is a diagram schematically showing the operation of optical information reading devices 1A, 1B, and 1C according to embodiments of the present invention, and the operation of an optical information reading system S including these optical information reading devices 1A, 1B, and 1C and a setting device 100. The number of optical information reading devices 1A, 1B, and 1C constituting the optical information reading system S is not particularly limited, and may be one or any plurality. In the example shown in FIG. 1, three optical information reading devices, namely, a first optical information reading device 1A, a second optical information reading device 1B, and a third optical information reading device 1C, are provided.

[0020] The setting device 100 can use a general-purpose or dedicated electronic computer, a portable terminal, etc., and includes a display 101 composed of a liquid crystal display, etc., a keyboard 102, a mouse 103, a communication unit 104, a control unit 105, and a storage unit 106. The keyboard 102 and the mouse 103 are operating devices for the user to operate the setting device 100. By operating the keyboard 102 and the mouse 103, it is possible to input arbitrary numbers, etc., and various settings can be performed. The communication unit 104 is connected to the network N and is configured to be able to communicate with the first to third optical information reading devices 1A to 1C. The storage unit 106 stores the operation program of the optical information reading system S, imaging conditions, reading conditions, code images, reading results, etc.

[0021] In the example shown in FIG. 1, a plurality of workpieces W are placed on the upper surface of the conveyor belt B and are being conveyed in the direction of arrow Y in FIG. 1. The workpiece W is an article such as a package, a product, various parts, an electrical product, an electronic device, etc. In the most upstream in the feeding direction of the belt conveyor B, the first process is performed on the workpiece W, in the middle part, the second process is performed on the same workpiece W, and in the most downstream, the third process is performed on the same workpiece W. In each process, for example, printing, pasting, attachment work of parts, etc., various processing, painting, adjustment, etc. are performed.

[0022] At a position above and separated from the workpiece W placed on the belt conveyor B in the first process, the first optical information reading device 1A is installed. The first optical information reading device 1A is a code reader configured to be able to photograph the code given to the workpiece W and decode the code included in the code image obtained by the photographing to read various information (string data). Also, at a position above and separated from the workpiece W placed on the belt conveyor B in the second process, the second optical information reading device 1B is installed, and further, at a position above and separated from the workpiece W placed on the belt conveyor B in the third process, the third optical information reading device 1C is installed.

[0023] In the example shown in FIG. 1, the first to third optical information reading devices 1A, 1B, and 1C are stationary (fixed). When operating the stationary first to third optical information reading devices 1A, 1B, and 1C, they are fixed to a bracket or the like (not shown) so as not to move and are used. Incidentally, the stationary first to third optical information reading devices 1A, 1B, and 1C may be used while being gripped by a robot (not shown). Further, the codes of the work W in a stationary state may be read by the first to third optical information reading devices 1A, 1B, and 1C. The operation time of the stationary first to third optical information reading devices 1A, 1B, and 1C is when performing the operation of sequentially reading the codes of the work W conveyed by the conveyor belt B for conveyance.

[0024] The first to third steps may be performed on the same conveyor belt B, or some of the steps may be performed on another conveyor belt (not shown), or all of the steps may be performed on different conveyor belts. The work W may be conveyed by a conveying device (not shown) other than the conveyor belt B. The first to third steps may be performed within the same factory or within different factories. The number of steps is not limited to three, and only one step may be sufficient. Further, the above steps may be a conveying step for simply conveying the work W.

[0025] A code is provided at a position on a part of the outer surface of each work W where imaging is possible from above. The code includes both a barcode and a two-dimensional code. Examples of the two-dimensional code include a QR code (registered trademark), a micro QR code, a Data matrix (Data code), a Veri code, an Aztec code, a PDF417, a Maxi code, and the like. The two-dimensional code has a stack type and a matrix type, but the present embodiment can be applied to any two-dimensional code. The code may be provided by directly printing or engraving on the work W, or may be provided by printing on a label and then attaching it to the work W, and the means and method thereof are not limited.

[0026] (Reading start trigger signal) The first to third optical information reading devices 1A, 1B, and 1C are wired-connected to a programmable logic controller (PLC) 130 via a signal line 130a. However, it is not limited to this. The first to third optical information reading devices 1A, 1B, and 1C and the PLC 130 may incorporate communication modules to wirelessly connect the first to third optical information reading devices 1A, 1B, and 1C and the PLC 130. The PLC 130 is a control device for sequence control of the conveyor belt B and the first to third optical information reading devices 1A, 1B, and 1C, and a general-purpose PLC can be used.

[0027] During operation, the first to third optical information reading devices 1A, 1B, and 1C each receive a reading start trigger signal that defines the start timing of code reading from the PLC 130 via the signal line 130a. Then, the first to third optical information reading devices 1A, 1B, and 1C perform code image acquisition and decoding processing based on this reading start trigger signal. After that, the reading result is transmitted to the PLC 130 via the signal line 130a. In this way, during the operation of the first to third optical information reading devices 1A, 1B, and 1C, the input of the reading start trigger signal and the output of the decoding result are repeatedly performed via the signal line 130a between the first to third optical information reading devices 1A, 1B, and 1C and an external control device such as the PLC 130. Note that the input of the reading start trigger signal and the output of the reading result may be performed via the signal line 130a between the optical information reading device 1 and the PLC 130 as described above, or may be performed via other signal lines not shown. For example, a sensor for detecting the arrival of the workpiece W may be directly connected to the first to third optical information reading devices 1A, 1B, and 1C, and the reading start trigger signal may be input from the sensor to the first to third optical information reading devices 1A, 1B, and 1C.

[0028] (Configuration of the optical information reading device) The first to third optical information reading devices 1A, 1B, and 1C are the same. Hereinafter, the configuration of the first optical information reading device 1A will be described. FIG. 2 is a block diagram of the first optical information reading device 1A, and FIGS. 3 to 6 are views showing the appearance of the first optical information reading device 1A. The first optical information reading device 1A includes a housing 2, an illumination unit 4 and a camera 5, and a processor 20. The illumination unit 4 is a part that illuminates the workpiece W, and the camera 5 is a part that captures the workpiece W with a code attached thereto in a state illuminated by the illumination unit 4 and acquires a code image including the code. The decoding unit 22 of the processor 20 is an example of decoding means for decoding the code image acquired by the camera 5.

[0029] In the description of this embodiment, as shown in FIGS. 3 to 6, the up and down, left and right, and front and back of the optical information reading device 1 are defined respectively, but this is only for the convenience of explanation and does not limit the orientation of the optical information reading device 1 during use. That is, as shown in FIG. 1, it is possible to install and use the optical information reading device 1A with its front (front side) facing down and its rear (back side) facing up, with its front facing up, or with its front in an inclined state. Also, the left and right directions of the optical information reading device 1A can also be referred to as the width direction.

[0030] As shown in FIGS. 3 to 6, the housing 2 has a substantially rectangular box shape that is long in the vertical direction and has at least a front surface 2a, a rear surface 2b, a left side surface 2c, a right side surface 2d, an upper surface 2e, and a lower surface 2f. In the front view shown in FIG. 3, when assuming a first virtual line L1 that is a straight line extending in the vertical direction at the center in the left and right directions of the front surface 2a of the housing 2 and a second virtual line L2 that is a straight line extending in the left and right directions at the center in the vertical direction of the front surface 2a of the housing 2, the intersection of the first virtual line L1 and the second virtual line L2 is the center C of the front surface 2a of the housing 2. The first virtual line L1 and the second virtual line L2 are orthogonal to each other.

[0031] The camera 5 shown in FIG. 7 is provided inside the housing 2. As shown in FIG. 2, the camera 5 includes an image sensor 5a that captures an image of the cord illuminated by the illumination unit 4, an optical system 5b having a lens and the like, and an AF module (auto focus module) 5c. The optical system 5b is configured such that light reflected from the portion of the work W where the cord is provided is incident thereon. The image sensor 5a is an image sensor composed of a light receiving element such as a CCD (charge-coupled device) or a CMOS (complementary metal oxide semiconductor) that converts the image of the cord obtained through the optical system 5b into an electrical signal. The image sensor 5a is connected to the processor 20, and the electrical signal converted by the image sensor 5a is input to the processor 20. Further, the AF module 5c is a mechanism that performs focusing by changing the position and refractive index of the focusing lens among the lenses constituting the optical system 5b. The AF module 5c is also connected to the processor 20 and is controlled by the processor 20.

[0032] The camera 5 is fixed to the housing 2 in a state of being housed inside the housing 2. The optical system 5b of the camera 5 is disposed so as to face the outside from the photographing window 2g (shown in FIG. 3 and the like) formed in the front surface 2a of the housing 2. The optical axis X1 of the optical system 5b extends in the front-rear direction of the housing 2. In a front view, the camera 5 is disposed offset from the center C of the housing 2. That is, the optical axis X1 of the optical system 5b is separated from the center C of the housing 2 by a distance D1 upward. The mounting position of the camera 5 inside the housing 2 is set so that the optical system 5b is positioned at this position.

[0033] As shown in FIGS. 3 and 7, the lighting unit 4 is provided around the camera 5 in the housing 2 and has a light-emitting element such as a light-emitting diode for irradiating light to the outside, and forms a plurality of groups. As also shown in FIG. 7, the lighting unit 4 of this embodiment includes a first group (first lighting group) 4a composed of two light-emitting elements, a second group (second lighting group) 4b composed of more than two light-emitting elements, and a third group (third lighting group) 4c composed of two light-emitting elements. Although details will be described later, the first group 4a is non-polarized and non-diffused lighting, the second group 4b is non-polarized and diffused lighting, and the third group 4c is non-diffused and polarized lighting. Note that the lighting unit 4 may be composed of a polarized lighting group and a diffused lighting group, and this form is also included in the present invention.

[0034] As described above, the first group 4a and the second group 4b differ in the number of light-emitting elements. Specifically, the number of light-emitting elements is set such that the second group 4b, which is diffused lighting, has a larger number of light-emitting elements than the first group 4a, which is non-diffused lighting. This makes it possible to irradiate diffused lighting over a wide range. Note that the number of light-emitting elements is an example, and the first group 4a and the third group 4c may be composed of three or more light-emitting elements.

[0035] It is also possible to adopt a configuration in which the illumination intensity per light-emitting element in the first group 4a is different from the illumination intensity per light-emitting element in the second group 4b. Specifically, the light-emitting elements are selected or controlled such that the illumination intensity per light-emitting element in the second group 4b is higher than that in the first group 4a. Also, it is possible to adopt a configuration in which the size of each light-emitting element in the first group 4a is different from the size of each light-emitting element in the second group 4b. Specifically, the light-emitting elements are selected such that the size of each light-emitting element in the first group 4a is larger than that in the second group 4b. Also, it is possible to adopt a configuration in which the color of the light-emitting elements in the first group 4a is different from the color of the light-emitting elements in the second group 4b. For example, the color of the light-emitting elements in the first group 4a can be red, and the color of the light-emitting elements in the second group 4b can be blue, but it is not limited thereto. Also, the light-emitting elements in the third group 4c are different from the light-emitting elements in the second group 4b. The color of the light-emitting elements in the third group 4c is the same as the color of the light-emitting elements in the first group 4a, and specifically, it can be red. Also, the light-emitting elements in the first group 4a and the light-emitting elements in the third group 4c can be the same.

[0036] As shown in FIG. 7, a plurality of light-emitting elements constituting the first to third groups 4a, 4b, and 4c are mounted on the same substrate 4d. That is, this substrate 4d extends in the vertical and horizontal directions within the housing 2. The optical system 5b of the camera 5 is disposed so as to penetrate a portion offset upward from the center C of the housing 2. A plurality of light-emitting elements constituting the second group 4b are disposed below the camera 5 on the substrate 4d. The region where the light-emitting elements constituting the second group 4b are disposed is wider than the region where the light-emitting elements constituting the first group 4a are disposed. As shown in FIG. 3, the optical axis X2 of the second group 4b is located at the center of the region where the light-emitting elements constituting the second group 4b are disposed.

[0037] In addition, the two light-emitting elements constituting the first group 4a are respectively disposed on the left and right sides of the camera 5 on the substrate 4d. The optical axis X3 of the first group 4a is located between the two light-emitting elements constituting the first group 4a. In this embodiment, since the distance between the left light-emitting element of the first group 4a and the camera 5 is equal to the distance between the right light-emitting element of the first group 4a and the camera 5, it will be located at the center between the left light-emitting element and the right light-emitting element of the first group 4a.

[0038] In addition, the two light-emitting elements constituting the third group 4c are respectively disposed above the camera 5 on the left and right sides on the substrate 4d. The optical axis X4 of the third group 4c is located between the two light-emitting elements constituting the third group 4c. Also, the interval between the two light-emitting elements constituting the third group 4c is set to be narrower than the interval between the two light-emitting elements constituting the first group 4a.

[0039] The distance in the front view from the optical axis X1 of the camera 5 to the optical axis X2 of the second group 4b is set to be longer than the distance in the front view from the optical axis X1 of the camera 5 to the optical axis X4 of the third group 4c. That is, by arranging direct illumination (or polarized illumination) and diffused illumination across the optical axis X1 of the camera 5, the optical axis X4 is offset with respect to the center C of the front surface 2a of the housing 2, thereby increasing the area of the diffused illumination. In this embodiment, the polarized illumination and the diffused illumination are in the above form.

[0040] The distance in the front view from the optical axis X1 of the camera 5 to the center of the optical axis X4 of the third group 4c is set to be longer than the distance in the front view from the optical axis X1 of the camera 5 to the center of the optical axis X3 of the first group 4a. Also, the distance in the front view from the optical axis X1 of the camera 5 to the optical axis X2 of the second group 4b is set to be longer than the distance in the front view from the optical axis X1 of the camera 5 to the optical axis X4 of the third group 4c.

[0041] The optical information reading device 1A includes an aimer 10 composed of a light emitter such as a light-emitting diode. This aimer 10 irradiates light forward of the optical information reading device 1A to indicate the field of view of the camera 5 and the position of the optical axis of the illumination unit 4. The user can also install the optical information reading device 1A with reference to the light irradiated from the aimer 10. The aimer 10 is provided above the optical axis X1 of the camera 5, that is, on the side where the camera 5 is offset from the center C of the housing 2. Further, the aimer 10 is disposed between two light-emitting elements constituting the third group 4c of the illumination unit 4, and aimer light is irradiated from between these two light-emitting elements.

[0042] A polarizing plate 50, a diffusing plate 51, and a light-transmitting plate 52 are provided on the front surface 2a of the housing 2. That is, as shown by extracting only the front surface 2a of the housing 2 in FIG. 8, a first light projection window 2h is formed in front of the light-emitting elements constituting the third group 4c of the illumination unit 4 on the front surface 2a of the housing 2. Since the light-emitting elements constituting the third group 4c are arranged so as to sandwich the camera 5 in the left-right direction, two first light projection windows 2h are formed so as to sandwich the photographing window 2g in the left-right direction. The size of each first light projection window 2h is set to be smaller than the size of the photographing window 2g.

[0043] Furthermore, a second light projection window 2i is formed in front of the second group 4b of the lighting unit 4, and a third light projection window 2j is formed in front of the first group 4a. The second light projection window 2i is a large window corresponding to the region where the light-emitting elements constituting the second group 4b are disposed, and occupies, for example, a range of 1 / 2 or more, 2 / 5 or more of the total area of the front surface 2a. On the other hand, the third light projection window 2j is a window smaller than the second light projection window 2i corresponding to the region where the two light-emitting elements constituting the first group 4a are disposed, and has a size of 1 / 2 or less, or 1 / 3 or less of the second light projection window 2i. Since the two light-emitting elements constituting the first group 4a are separated in the left-right direction, the third light projection window 2j has a long shape in the left-right direction. Also, since an aiming member 10 is disposed between the two light-emitting elements constituting the first group 4a, the aiming light irradiated from this aiming member 10 passes through the third light projection window 2j and is irradiated to the outside. Also, the area of the second light projection window 2i is set to be larger than the combined area of the two first light projection windows 2h.

[0044] Polarizing plates 50 are respectively provided so as to face the outside from the two first light projection windows 2h, and are disposed in front of the third group 4c. In FIG. 8, the range where the polarizing plates 50 are provided is indicated by oblique lines extending diagonally downward to the left. The polarizing plates 50 have a polarizing effect.

[0045] The diffusion plates 51 are each provided so as to face the outside from the second light projection window 2i and are arranged in front of the second group 4b. The range where the diffusion plates 51 are provided in FIG. 8 is indicated by diagonal lines slanting downward to the right. The diffusion plates 51 are configured to diffuse and emit the light incident from the second group 4b. For example, the diffusion plates 51 are light-transmitting plates having fine unevenness formed on the surfaces thereof. These diffusion plates 51 do not have a polarization effect. Since the area of the second light projection window 2j is larger than that of the third light projection window 2j, the area of the diffusion plates 51 is larger than the area of the light-transmitting plates 52. The diffusion plates 51 are provided on the side of the front surface 2a of the housing 2 where the camera 5 is not offset, that is, below the center C of the housing 2. In this embodiment, the upper part of the diffusion plates 51 reaches the center C of the housing 2, but most of the diffusion plates 51 are provided below the center C.

[0046] The illuminance of the light of the first group 4a is set to be higher than that of the light of the second group 4b. Also, the illuminance of the light irradiated from the first group 4a through the light-transmitting plates 52 is set to be higher than that of the light irradiated from the second group 4b through the diffusion plates 51. Thereby, the work W can be irradiated with non-diffused strong light.

[0047] The light-transmitting plates 52 are each provided so as to face the outside from the third light projection window 2j and are arranged in front of the first group 4a. The range where the light-transmitting plates 52 are provided in FIG. 8 is indicated by cross-hatching. Thus, the light-transmitting plates 52 are provided on the opposite side of the diffusion plates 51 with the camera 5 interposed therebetween in a front view.

[0048] The lighting unit 4, the light-transmitting plate 52, and the diffusion plate 51 are asymmetric in either the vertical direction or the horizontal direction in the front view of the housing 2, and are symmetric in the other of the vertical direction and the horizontal direction. Specifically, as shown in FIG. 3, since the housing 2 has a vertically long shape, it has a major axis in the vertical direction in the front view. The major axis becomes the first virtual line L1, and the minor axis becomes the second virtual line L2. In this case, the lighting unit 4, the light-transmitting plate 52, and the diffusion plate 51 are line-symmetric (symmetric in the horizontal direction) with the first virtual line L1 as the center of symmetry. For example, the two light-emitting elements constituting the first group 4a of the lighting unit 4 are equidistant from the first virtual line L1 in the front view and have the same position in the vertical direction. Similarly, the two light-emitting elements constituting the third group 4c of the lighting unit 4 are also equidistant from the first virtual line L1 in the front view and have the same position in the vertical direction. In addition, the plurality of light-emitting elements constituting the second group 4b of the lighting unit 4 are arranged on the left side of the first virtual line L1 and on the right side of the first virtual line L1 in the front view, and the number of them is the same, and their positions in the vertical direction are also the same.

[0049] On the other hand, since the first group 4a and the third group 4c are arranged above the center C of the front surface 2a of the housing 2, and the second group 4b is mainly arranged below the center C, the second virtual line L2 is asymmetric (asymmetric in the vertical direction).

[0050] Note that the shape of the housing 2 may be such that the major axis extends in the horizontal direction while the minor axis extends in the vertical direction. In this case, the lighting unit 4, the light-transmitting plate 52, and the diffusion plate 51 are line-symmetric with the minor axis as the center of symmetry and are asymmetric with respect to the major axis.

[0051] In this embodiment, an example in which the polarizing plate 50, the diffusion plate 51, and the light-transmitting plate 52 are fixed to the front surface 2a of the housing 2 has been described. However, the present invention is not limited to this, and at least one of the polarizing plate 50, the diffusion plate 51, and the light-transmitting plate 52 may be detachably attached to the housing 2. Although not shown, for example, an attachment in which at least one of the polarizing plate 50, the diffusion plate 51, and the light-transmitting plate 52 is integrated with a frame body may be provided, and the frame body may be attached to the front surface 2a of the housing 2 using, for example, a claw fitting structure or a fastening and fixing structure using screws or the like. In this case, at least one of the polarizing plate 50, the diffusion plate 51, and the light-transmitting plate 52 can be attached or removed as needed. The attachment may have only the diffusion plate 51, only the polarizing plate 50, or both the diffusion plate 51 and the polarizing plate 50.

[0052] By providing the light-transmitting plate 52 above the camera 5 instead of on the side thereof, the light-transmitting plate 52 can be separated from the camera 5. As a result, it becomes difficult for specularly reflected light to enter the camera 5, and a good code image can be obtained. Further, by providing the light-transmitting plate 52 above, the light-transmitting plate 52 and the diffusion plate 51 can be separated from each other. As a result, it becomes easier to realize illumination that projects diffused illumination onto the back surface of the code.

[0053] (Molding of Diffusion Plate) FIGS. 9A and 9B show a diffusion plate unit 51A. The diffusion plate unit 51A is obtained by integrally molding the diffusion plate 51, the first lens 56, the second lens 57, and the aiming lens 58. The first lens 56 is disposed between the two light-emitting elements of the third group 4c and the polarizing plate 50. The second lens 57 is disposed between the two light-emitting elements of the first group 4a and the light-transmitting plate 52. By disposing the lenses 56 and 57 in front of the light-emitting elements, a large amount of light can be ensured over a wide range. The aiming lens 58 is disposed in front of the aimer 10. Since the diffusion plate 51 and the lenses 56, 57, and 58 are integrally molded, the number of parts can be reduced and the structure can be simplified. Note that the diffusion plate 51 and the lenses 56, 57, and 58 may be configured as separate parts.

[0054] In addition, since the light-emitting element has wire bonding or patterns on the light source, uneven light intensity may occur on the projection surface when the light of a single light-emitting element is condensed by a lens and projected. In the present embodiment, in order to avoid this uneven light intensity, a plurality of sets of the light-emitting element and the lens are mounted, and they are mounted so as not to be in the same direction as each other at the optical axis center of the light-emitting element. As a result, uneven light intensity is reduced as a whole.

[0055] (Illumination control unit) As shown in FIG. 2, the first group 4a, the second group 4b, and the third group 4c are connected to the processor 20 and are controlled by an illumination control unit 21 constituted by the processor 20. When the illumination control unit 21 lights the light-emitting elements of the second group 4b, it controls the illumination unit 4 so as not to light the light-emitting elements of the other illumination groups 4a and 4c. When the illumination control unit 21 lights the light-emitting elements of the first group 4a, it controls the illumination unit 4 so as not to light the light-emitting elements of the other illumination groups 4b and 4c. When the illumination control unit 21 lights the light-emitting elements of the third group 4c, it can control the illumination unit 4 so as not to light the light-emitting elements of the other illumination groups 4a and 4b. That is, the illumination control unit 21 is configured to be able to switch direct light (light transmitted through the light-transmitting plate 52), diffused light, and polarized light and irradiate the code.

[0056] Here, photographing of a code image by diffuse illumination will be described based on the schematic diagram shown in FIG. 10. When irradiating diffuse illumination from the second group 4b of the illumination unit 4 onto the work W to which the code is applied, it is possible to obtain a code image with high contrast by projecting the diffuse illumination onto the back surface of the code. In order to project the diffuse illumination onto the back surface of the code, for example, when a 10 mm square code is the imaging target, 20 mm square diffuse illumination is required. That is, it is necessary to irradiate the diffuse illumination on an area four times the area of the code. In the present embodiment, since the diffusion plate 51 is larger than the light-transmitting plate 52 and the polarizing plate 50 and is provided over a wide range of the front surface 2a of the housing 2, it is possible to irradiate the diffuse illumination over a wide range necessary for projecting the diffuse illumination onto the back surface of the code.

[0057] Also, in the case of the work W that does not require diffused light, by switching to direct light, the code can be irradiated with a large amount of light to obtain a high-contrast code image. Also, a high-contrast code image can be obtained by switching to polarized light as needed. Therefore, the range of the work W that can be read is expanded.

[0058] (Decode process) The decoder unit 22 is configured by the processor 20. The decoder unit 22 is a part that decodes the code image obtained by irradiating the code with the light from the first group 4a through the light-transmitting plate 52 and acquired by the camera 5, the code image obtained by irradiating the code with the light from the second group 4b through the diffuser plate 51 and acquired by the camera 5, and the code image obtained by irradiating the code with the light from the third group 4c through the polarizing plate 50 and acquired by the camera 5. The code image is stored in the image data storage unit 30a of the storage unit 30 shown in FIG. 2.

[0059] Before decoding the above code image, the decoder unit 22 performs image processing such as various image processing filters. Then, at the time of decoding, a conventionally well-known table can be used. Further, the decoder unit 22 checks whether the decoded result is correct according to a predetermined check method. When an error is found in the data, the correct data is calculated using an error correction function. The error correction function varies depending on the type of code. The decoder unit 22 stores the decoding result obtained by decoding the code in the decoding result storage unit 30b of the storage unit 30.

[0060] (Main body display unit) As shown in Fig. 5, a main body display unit 6 is provided on the upper surface 2e of the housing 2. The main body display unit 6 is composed of, for example, an organic EL display, a liquid crystal display, or the like. As shown in Fig. 2, the main body display unit 6 is connected to the processor 20. The main body display unit 6 can display, for example, a code image captured by the camera 5, a character string that is the result of decoding the code image, a reading success rate, a matching level, and the like. The reading success rate is the average reading success rate when multiple reading processes are executed. The matching level is a reading margin indicating the ease of reading of a code for which decoding has been successful. This can be obtained from the number of error corrections generated during decoding and can be represented, for example, by a numerical value. The smaller the number of error corrections, the higher the matching level (reading margin), while the larger the number of error corrections, the lower the matching level.

[0061] (Operation button) On the upper surface 2e of the housing 2, a select button 11 and an enter button 12 used when setting the optical information reading device 1A and the like are provided. The select button 11 and the enter button 12 are connected to the processor 20, and the processor 20 can detect the operation states of the select button 11 and the enter button 12. The select button 11 is a button operated when selecting one from a plurality of options displayed on the main body display unit 6. The enter button 12 is a button operated when confirming the result selected by the select button 11.

[0062] (Indicator) An indicator 9 is also provided on the upper surface 2e of the housing 2. The indicator 9 is connected to the processor 20 and can be composed of a light-emitting body such as a light-emitting diode. The operating state of the optical information reading device 1A can be notified to the outside by the lighting state of the indicator 9.

[0063] (Connector) At the lower part of the housing 2, a rotary connector 60 is provided. The rotary connector 60 is rotatably attached around the center line L3 shown in FIG. 5 with respect to the main body part of the housing 2. The rotary connector 60 is provided with a power connector 7 to which a power wiring for supplying power to the optical information reading device 1A is connected, and an Ethernet connector 8 connected to the setting device 100 and the PLC 130. Note that the Ethernet standard is an example, and signal lines of standards other than the Ethernet standard can also be used.

[0064] By rotating the rotary connector 60, as shown in FIGS. 3 to 5, the power connector 7 and the Ethernet connector 8 can be switched to a posture in which they protrude downward from the housing 2, and as shown in FIG. 6, the power connector 7 and the Ethernet connector 8 can be switched to a posture in which they protrude rearward from the housing 2. Depending on the installation location of the optical information reading device 1A, the rotary connector 60 can be rotated to protrude the power connector 7 and the Ethernet connector 8 in a desired direction.

[0065] (Model without the connector rotation mechanism) In the above embodiment, the rotary connector 60 is mounted, but the present invention is not limited to this. For example, as shown in FIGS. 11 to 13, the present invention can also be applied when the rotary connector 60 is not mounted. In the example shown in FIGS. 11 to 13, the power connector 7 and the Ethernet connector 8 protrude downward from the lower surface 2f of the housing 2, and the protruding direction is fixed.

[0066] (Configuration of the communication unit 32) The optical information reading device 1A has a communication unit 32. The communication unit 32 is a part that communicates with the setting device 100 and the PLC 130. The communication unit 32 may have a Web server function, or may have an I / O unit connected to the setting device 100 and the PLC 130, a serial communication unit such as RS232C, or a network communication unit such as a wireless LAN or a wired LAN.

[0067] (Configuration with a display) In the example shown in FIG. 1, the setting device 100 includes the display 101, but the display 101 may be a part of the first optical information reading device 1A. In this case, an optical information reading device including an optical information reading device main body having the housing 2, the illumination unit 4, the camera 5, the light-transmitting plate 52, the diffusion plate 51, and the processor 20, and the display 101 can be provided.

[0068] (Tuning) The tuning execution unit 23 is configured by the processor 20 shown in FIG. 2. After the AF module 5c is operated for focusing, the tuning execution unit 23 changes the imaging conditions of the camera 5, the decoding conditions of the decoding process, etc., repeats the imaging and decoding process of the code, and based on the matching level indicating the ease of reading the code (the margin of decoding) calculated under each imaging condition and decoding condition, executes a tuning process for determining the optimal imaging conditions and decoding conditions. For example, at the time of setting the optical information reading device 1A, the tuning execution unit 23 is a part that changes imaging conditions such as the gain of the camera 5, the light amount of the illumination unit 4, illumination switching (switching between direct light, diffused light, and polarized light), exposure time, etc., and image processing conditions, and sets various conditions (tuning parameters) so as to be conditions suitable for decoding. The image processing conditions are coefficients of an image processing filter (strength of the filter) for a code image before decoding, switching of the image processing filter when there are a plurality of image processing filters, combinations of different types of image processing filters, etc. Appropriate imaging conditions and image processing conditions vary depending on the influence of external light on the work W during conveyance, the color and material of the surface to which the code is attached, etc. Therefore, the tuning execution unit 23 searches for more appropriate imaging conditions and image processing conditions and sets the above conditions.

[0069] Specifically, as shown in the flowchart of FIG. 14, in step SB1 after starting, the tuning execution unit 23 controls the lighting unit 4 and the camera 5 to generate a code image in the camera 5, and the tuning execution unit 23 acquires the code image. At this time, the decoding process parameters regarding the presence or absence and type of image processing filters executed before the decoding process, lighting conditions, shooting conditions, etc. are set to arbitrary parameters. Next, it proceeds to step SB2, and the tuning execution unit 23 causes the decoding unit 22 to execute the decoding process on the acquired code image.

[0070] After the decoding process, it proceeds to step SB3, and the tuning execution unit 23 determines whether the decoding process in step SB2 was successful. If it is determined as NO in step SB3 and the decoding process in step SB2 fails, that is, if the code cannot be read, it proceeds to step SB4. After changing the decoding process parameters to other parameters, the decoding process is executed again in step SB2. If the decoding process fails with all decoding process parameters, this flow is terminated and the user is notified.

[0071] On the other hand, if it is determined as YES in step SB3 and the decoding process in step SB2 is successful, it proceeds to step SB5, and the tuning execution unit 23 evaluates the reading margin based on the above decoding process result and stores it temporarily.

[0072] In step SB6, it is determined whether the execution of the decoding process has been completed with all decoding process parameters. If it is determined as NO in step SB6 and the execution of the decoding process has not been completed with all decoding process parameters, it proceeds to step SB7, and the decoding process parameters are changed to other parameters for decoding.

[0073] On the other hand, when it is determined YES in step SB7 and the execution of the decoding process is completed with all the decoding process parameters, the process proceeds to step SB8. In step SB8, the tuning execution unit 23 selects the decoding process parameter with the highest reading margin from among all the decoding process parameters, and determines the selected decoding process parameter as the parameter to be applied during operation.

[0074] In the tuning process, the lighting conditions are also set to appropriate conditions. That is, when the optical information reading device 1A is in operation, it is possible to set which lighting group among the first to third groups 4a, 4b, and 4c of the lighting unit 4 is to be used. Regarding which lighting group to use, it may be set by the above-described tuning, or may be set to be the lighting group selected by the user. For example, a user interface that enables selection of the first to third groups 4a, 4b, and 4c is generated and displayed on the display 101, and if the user operates the keyboard 102 or the mouse 103 to select a desired lighting group, the selection result can be reflected during operation.

[0075] As a result of the tuning executed by the tuning execution unit 23, a set of parameters that constitute the various set conditions and the various conditions set by the user is the parameter set. This parameter set is also the reading condition applied when decoding the code image. The parameter set can also be called a bank, and in this embodiment, a plurality of parameter sets can be stored. The reading condition applied when decoding the code image and the read data are stored in the parameter set storage unit 30c in association with each other.

[0076] In this optical information reading device 1A, among a plurality of parameter sets stored in the parameter set storage unit 30c, it is configured to be able to switch from one parameter set to another. The switching of the parameter set can be performed by the user or can also be configured to be performed by a switching signal from an external control device such as the PLC 130. When the user performs the switching of the parameter set, the setting device 100 or the operation buttons 11 and 12 may be operated. The selected parameter set is used during the operation of the optical information reading device 1A, and the unselected parameter set is not used during the operation of the optical information reading device 1A. That is, it is possible to switch from one parameter set to another.

[0077] (Display) Various user interface screens can be displayed on the display 101. The user interface screen can be generated, for example, by the control unit 105 of the setting device 100.

[0078] FIG. 15 shows an example of a first user interface screen 300 displayed on the display 101. The first user interface screen 300 is a screen for extracting records having the same read data from a plurality of optical information reading devices 1A, 1B, 1C (simplified as readers 1A, 1B, 1C in the figure) and displaying code images, read times, various conditions, etc. In the header section 301 of the first user interface screen 300, it is possible to set filter / search conditions, and a filter setting area 301a, a search setting area 301b, a reader selection area 301c, and a period specification area 301d are provided. In the filter setting area 301a, conditions for selecting the target (display target) to be displayed on the first user interface screen 300 from among a large number of records are set. For example, conditions such as "display all" and "display only errors" can be set. An error is a record that could not be read or for which the reading failed. In the search setting area 301b, it is possible to set conditions for searching for records having specified read data from among the records that are the display target. In the period specification area 301d, it is possible to specify the period for extracting the display target.

[0079] In the reader selection area 301c, the optical information reading device to be displayed below the header section 301 is selected from among the plurality of optical information reading devices 1A, 1B, 1C. For example, the first to third optical information reading devices 1A, 1B, 1C existing on the same network N are searched, and the IP addresses of the searched optical information reading devices are acquired. Then, when the user operates the reader selection area 301c to perform a selection operation on the first to third optical information reading devices 1A, 1B, 1C, the control unit 105 detects the selection operation and selects the first to third optical information reading devices 1A, 1B, 1C.

[0080] Below the header section 301 of the first user interface screen 300, a reader display area 302 and a record display area 303 for displaying a list of read data are provided. In the reader display area 302, information on the selected optical information reader is displayed. In this example, the first to third optical information readers 1A, 1B, and 1C are displayed, but if only one is selected, only one can be displayed. In the reader display area 302, there is a first area 302a where, as information on the optical information reader, a name for identifying the optical information reader, a model, an illustration, a photograph, etc. showing the appearance of the optical information reader are displayed, and the control unit 105 causes the information on the selected optical information reader to be displayed in the first area 302a. Since it becomes possible to determine the model, etc. from the appearance of the optical information reader, it is easy to know which model of optical information reader is installed in which process.

[0081] In addition, in the reader display area 302, there is a second area 302b where a code image captured by the optical information reader is displayed. Also, in the reader display area 302, there is a third area 302c for displaying the matching level (MLV) and the decoding time (time) when decoding with the optical information reader.

[0082] Below the reader display area 302, a reading distance display area 304, an installation angle display area 305, a bank information display area 306, an illumination information display area 307, a filter display area 308 for displaying the applied image processing filter, etc. are provided.

[0083] In the reading distance display area 304, the distance between the optical information reading device and the workpiece (reading distance) is displayed. In the installation angle display area 305, the installation angle of the optical information reading device (tilt angle, pitch angle, etc.) is displayed. In the bank information display area 306, the number of the bank (parameter set number) that was applied when the camera 5 acquired the code image and the reading was successful is displayed. In the illumination information display area 307, illumination information indicating whether the illumination unit 4 irradiated direct light, diffused light, or polarized light when the camera 5 acquired the code image is displayed. The illumination information is information included in the parameter set. The illumination information displayed in this illumination information display area 307 is associated with the code image. In this figure, it can be seen that the code image acquired by the first optical information reading device 1A is an image taken with direct light, the code image acquired by the second optical information reading device 1B is an image taken with diffused light, and the code image acquired by the third optical information reading device 1C is an image taken with polarized light.

[0084] FIG. 16 shows an example of the second user interface screen 320. On this second user interface screen 320, there are provided a code image display area 321, a first area 322 for displaying a code image acquired by irradiating polarized light, a second area 323 for displaying a code image acquired by irradiating direct light, and a third area 324 for displaying a code image acquired by irradiating diffused light. Since the second user interface screen 320 can display the code images acquired by irradiating polarized light, direct light, and diffused light in a comparable manner, the user can determine which illumination is suitable while looking at the actual images.

[0085] (Operational effects of the embodiment) As described above, according to this embodiment, the illumination unit 4 has a first group 4a and a second group 4b. A light-transmitting plate 52 is provided in front of the first group 4a, and a diffusion plate 51 is provided in front of the second group 4b. Therefore, the light from the second group 4b is diffused by the diffusion plate 51 and then irradiated onto the code. Since the diffusion plate 51 is larger than the light-transmitting plate 52 through which the light from the first group 4a passes, it is possible to irradiate the diffused light 51 over a wide range, that is, for example, irradiate the diffused light over an area four times that of the code. As a result, even when the surface of the workpiece W is a mirror surface, a high-contrast code image can be acquired by the camera 5. Consequently, the reading success rate can be increased.

[0086] On the other hand, the light from the first group 4a is irradiated onto the code after passing through the light-transmitting plate 52. Since the amount of light when passing through the light-transmitting plate 52 is larger than when passing through the diffusion plate 51, it is possible to ensure sufficient light amount for reading even for workpieces that are difficult to read by diffusion illumination, and the corresponding range of readable codes is expanded.

[0087] The above-described embodiment is merely an example in all respects and should not be construed in a limiting sense. Further, modifications and changes belonging to the equivalent scope of the claims are all within the scope of the present invention.

Industrial Applicability

[0088] As described above, the optical information reading device according to the present invention can be used, for example, when reading a code such as a two-dimensional code.

Explanation of Reference Numerals

[0089] 1A First optical information reading device 2 Housing 2a Front surface (first surface) 4 Illumination unit 4a First group 4b Second group 4c Third group 5 Camera 21 Illumination control unit 22 Decoding section 50 Polarizer 51 Diffusion plate 52 Light-transmitting plate 101 Display

Claims

1. An optical information reading system comprising an optical information reading device that reads a code attached to a workpiece and a user interface that sets the optical information reading device, The optical information reading device is A diffuse lighting unit that irradiates diffuse light onto a workpiece to which a code is attached; A direct illumination unit that irradiates the workpiece with direct light having a narrower illumination range than the diffused light; A polarized illumination unit that irradiates the workpiece with polarized light having a narrower irradiation range than the diffused light; A camera that photographs the workpiece and acquires a code image including the code; a processor that controls one of the diffuse illumination unit, the direct illumination unit, and the polarized illumination unit to emit light and executes a decoding process on the code image acquired by the camera; Equipped with The user interface includes: An optical information reading system that displays at least one of a diffuse light image captured by the camera by irradiating the diffuse light, a direct light image captured by the camera by irradiating the direct light, and a polarized light image captured by the camera by irradiating the polarized light on a display in association with information from the corresponding lighting unit.

2. 2. The optical information reading system according to claim 1, The user interface of the optical information reading system displays at least two of the diffuse light image, the direct light image, and the polarized light image on the display in a comparative manner.

3. 2. The optical information reading system according to claim 1, The user interface of the optical information reading system displays, on the display, at least one of the direct light image and the polarized light image and the diffuse light image in a comparative manner.

4. 2. The optical information reading system according to claim 1, The user interface is an optical information reading system that displays the diffuse light image, the direct light image, and the polarized light image on the display in a comparative manner.

5. 5. An optical information reading system according to claim 2, An optical information reading system, wherein the screen displayed by the user interface includes a code image display area in which only one image selected by a user from the plurality of images displayed in a comparative manner is displayed larger than the other images.

6. 6. An optical information reading system according to claim 1, the processor executes a tuning process for determining one parameter set including an imaging condition of the camera and a decoding condition of the decoding process by changing the imaging condition and the decoding condition; An optical information reading system, wherein the change in the imaging condition includes switching illumination to any one of the diffuse light, the direct light, and the polarized light.

7. 7. The optical information reading system according to claim 6, The user interface of the optical information reading system displays images acquired under the imaging conditions of each of a plurality of parameter sets created by executing the tuning process, and accepts selection of a parameter set to be used in operation from a user.

8. An optical information reading system comprising an optical information reading device that reads a code attached to a workpiece and a user interface that sets the optical information reading device, The optical information reading device is A diffuse lighting unit that irradiates diffuse light onto a workpiece to which a code is attached; A non-diffuse illumination unit that irradiates the workpiece with non-diffuse light having a narrower irradiation range than the diffuse light; A camera that photographs the workpiece and acquires a code image including the code; a processor that performs a decoding process on a code image captured by the camera using one of the diffuse illumination unit and the non-diffuse illumination unit; Equipped with The user interface is an optical information reading system that displays on a display at least one of a diffuse light image acquired by the camera by irradiating the diffuse light and a non-diffuse light image acquired by the camera by irradiating the non-diffuse light, in association with information about the corresponding lighting unit.

9. 9. The optical information reading system according to claim 8, The user interface is an optical information reading system that displays the diffuse light image and the non-diffuse light image on the display device so as to be comparable.

10. 10. The optical information reading system according to claim 8, An optical information reading system in which the screen displayed by the user interface includes a code image display area in which only one of the diffused light image and the non-diffused light image, selected by the user, is displayed separately and larger than the other images.

11. 11. An optical information reading system according to claim 8, the processor executes a tuning process for determining one parameter set including an imaging condition and a decoding condition by changing an imaging condition of the camera and a decoding condition of the decoding process; An optical information reading system, wherein the change in the imaging condition includes switching illumination to either the diffused light or the non-diffused light.

12. 12. The optical information reading system according to claim 11, The user interface of the optical information reading system displays images acquired under the imaging conditions of each of a plurality of parameter sets created by executing the tuning process, and accepts selection of a parameter set to be used in operation from a user.

Images