Optical information reading system and optical information reading device

Abstract

To enable wide-area illumination by diffused illumination while miniaturizing a housing, and to expand the range of application to various works by enabling reading even of works that are difficult to read by diffused illumination. [Solution] The fixed optical information reading device 1A comprises a light-transmitting plate 52 provided in front of the first lighting group 4a, a diffusion plate 51 provided in front of the second lighting group 4b and having a larger area than the light-transmitting plate 52, and a decoding means for decoding a code image obtained by a camera by irradiating a code with light from the first lighting group 4a through the light-transmitting plate 52, and a code image obtained by the camera by irradiating a code with light from the second lighting group 4b through the diffusion plate 51.

Description

[Technical Field]

[0001] The present disclosure relates to a fixed optical information reading device that reads a code attached to a workpiece. [Background technology]

[0002] Optical information readers include handheld types that are held by hand and fixed types that are installed and used in a fixed state on a factory line, etc. Fixed-type optical information readers are disclosed, for example, in Patent Documents 1 and 2. The optical information reader of Patent Document 1 includes a first illumination unit that irradiates the workpiece with illumination light via a polarizing filter, and a second illumination unit that irradiates the workpiece with illumination light without passing through a polarizing filter. The optical information reader of Patent Document 2 includes a diffuse reflection member that diffuses and reflects light that is emitted from the illumination unit and specularly reflected by the surface of the workpiece. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-33787 [Patent Document 2] Japanese Patent Application Publication No. 2016-218588 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when photographing a code, if the surface of the workpiece on which the code is applied is mirrored, the contrast of the code image may be low, making it difficult to read. Therefore, when photographing such a mirrored workpiece, diffuse lighting is used, and by illuminating the background of the code with diffuse lighting, it is possible to obtain a code image with high contrast.

[0005] However, to obtain a high-contrast code image using diffused lighting, it is necessary to irradiate an area that is at least twice the vertical dimension and twice the horizontal dimension of the code, i.e., an area four times the size of the code. Meanwhile, there is a demand for the housing of the optical information reader to be as small as possible, taking into consideration the ease of installation on, for example, a factory line. Therefore, it has been difficult to achieve both a compact housing and diffused lighting that can irradiate a wide area.

[0006] Furthermore, because diffuse lighting diffuses light, the contrast of the code image may be reduced due to insufficient light, making it difficult to read the code. Therefore, if only diffuse lighting is installed, the reading range will be narrowed.

[0007] The present disclosure has been made in consideration of these points, and its purpose is to enable wide-area illumination with diffused lighting while miniaturizing the housing, and to enable workpieces that are difficult to read with diffused lighting to be read with powerful lighting, thereby expanding the range of workpieces that can be handled. [Means for solving the problem]

[0008] To achieve the above object, one aspect of the present disclosure can be based on a fixed optical information reading device. The optical information reading device includes a housing, a camera provided in the housing and configured to photograph a workpiece having a code attached thereto and acquire a code image including the code, an illumination unit provided around the camera within the housing and including a plurality of groups of light-emitting elements for illuminating the outside, a light-transmitting plate provided on a first surface of the housing and positioned in front of the first illumination group, a diffusion plate provided on the first surface of the housing and positioned in front of the second illumination group, the diffusion plate having an area larger than the light-transmitting plate, and a decoding means configured to decode the code image acquired by the camera by illuminating the code with light from the first illumination group via the light-transmitting plate and the code image acquired by the camera by illuminating the code with light from the second illumination group via the diffusion plate.

[0009] With this configuration, the light from the second lighting group is diffused by the diffuser plate before being irradiated onto the code. Because the diffuser 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 area, i.e., an area four times the size of the code. This allows the camera to capture a high-contrast code image even if the workpiece surface is mirror-finished.

[0010] On the other hand, the light from the first lighting group passes through a light-transmitting plate before irradiating the code. The amount of light that passes through the light-transmitting plate can be made greater than when it passes through a diffuser plate, so even workpieces that are difficult to read with diffused lighting can be read with a sufficient amount of light, expanding the range of codes that can be read. The light-transmitting plate and diffuser plate can be attached detachably to the housing.

[0011] In another embodiment, the distance between the center of the optical axis of the camera and the center of the optical axis of the second lighting group can be made 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, thereby making the diffuser plate provided in front of the second lighting group larger.

[0012] In another aspect, when comparing the light-emitting elements constituting the first lighting group with the light-emitting elements constituting the second lighting group, at least one of the number, color, lighting intensity, and size is different, which allows for more diverse lighting and further expands the range of readings that can be accommodated.

[0013] The illumination unit according to another aspect has a third illumination group and a polarizing plate in front of the third illumination group, which makes it possible to emit polarized light. The polarizing plate can be detachably attached to the housing.

[0014] In another aspect, a code image including a code can be acquired by switching between direct light, diffused light, and polarized light and irradiating the code with the light. In this case, the code image can be associated with illumination information indicating whether direct light, diffused light, or polarized light was irradiated when the optical information reader acquired the code image and displayed on the display, allowing the user to easily check the illumination information.

[0015] In another aspect, the configuration may include a polarizing plate provided on the first surface of the housing and positioned in front of the third lighting group, a diffuser plate provided on the first surface of the housing and positioned in front of the second lighting group, the diffuser plate having a larger area than the polarizing plate, and a decoding means for decoding a code image obtained by a camera by irradiating a code with light from the third lighting group through the polarizing plate, and a code image obtained by the camera by irradiating a code with light from the second lighting group through the diffuser plate. [Effects of the Invention]

[0016] As described above, while miniaturizing the housing, it is possible to illuminate a wide area with diffused lighting, and it is also possible to read even workpieces that are difficult to read with diffused lighting, thereby expanding the range of applications. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram illustrating the optical information reader during operation. [Figure 2] FIG. 1 is a block diagram of an optical information reader. [Figure 3] FIG. 2 is a front view of the optical information reader. [Figure 4] FIG. 2 is a perspective view of the optical information reader as seen from the connector side. [Figure 5] FIG. 2 is a perspective view of the optical information reader as seen from the rear side. [Figure 6] FIG. 10 is a perspective view showing a state in which the connector is rotated. [Figure 7] FIG. 2 is a perspective view showing the internal structure of the optical information reader. [Figure 8]FIG. 2 is a front view showing the structure of the front surface of the housing. [Figure 9A] FIG. [Figure 9B] FIG. 2 is a perspective view of a diffusion plate unit. [Figure 10] FIG. 10 is a diagram illustrating a code image captured with diffused illumination. [Figure 11] FIG. 10 is a front view of an optical information reader that does not have a connector rotation mechanism. [Figure 12] FIG. 10 is a perspective view of an optical information reader not provided with a connector rotation mechanism, as viewed from the connector side. [Figure 13] FIG. 10 is a perspective view of an optical information reader not provided with a connector rotation mechanism, as viewed from the rear side. [Figure 14] 10 is a flowchart illustrating an example of a tuning procedure performed by a tuning execution unit. [Figure 15] FIG. 10 is a diagram illustrating an example of a first user interface screen. [Figure 16] FIG. 10 is a diagram illustrating an example of a second user interface screen. DETAILED DESCRIPTION OF THE INVENTION

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

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

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

[0021] In the example shown in Fig. 1, a plurality of workpieces W are placed on the upper surface of a transport belt conveyor B and are transported in the direction of arrow Y in Fig. 1. The workpieces W are, for example, parcels, merchandise, various parts, electrical products, electronic devices, and other articles, and a first process is performed on the workpieces W at the most upstream position in the transport direction of the belt conveyor B, a second process is performed on the same workpieces W at the middle position, and a third process is performed on the same workpieces W at the most downstream position. In each process, for example, printing, pasting, attaching parts, etc., various processing, painting, adjustment, etc. are performed.

[0022] A first optical information reading device 1A is installed at a location above and away from the workpiece W placed on the belt conveyor B in the first process. The first optical information reading device 1A is a code reader configured to photograph the code attached to the workpiece W and decode the code contained in the code image acquired by photographing to read various information (character string data). Furthermore, a second optical information reading device 1B is installed at a location above and away from the workpiece W placed on the belt conveyor B in the second process, and a third optical information reading device 1C is installed at a location above and away from the workpiece W placed on the belt conveyor B in the third process.

[0023] In the example shown in FIG. 1, the first to third optical information readers 1A, 1B, and 1C are stationary (fixed). When these stationary first to third optical information readers 1A, 1B, and 1C are in operation, they are fixed to a bracket or the like (not shown) to prevent movement. The stationary first to third optical information readers 1A, 1B, and 1C may also be used while being held by a robot (not shown). The codes on stationary workpieces W may also be read by the first to third optical information readers 1A, 1B, and 1C. The stationary first to third optical information readers 1A, 1B, and 1C are in operation when they are sequentially reading the codes on the workpieces W transported by the transport belt conveyor B.

[0024] The first to third steps may be performed on the same belt conveyor B, some steps may be performed on a different belt conveyor (not shown), or all steps may be performed on different belt conveyors. The work W may be transported by a transport device (not shown) other than the belt conveyor B. The first to third steps may be performed in the same factory or in different factories. The number of steps is not limited to three, and may be only one step. Furthermore, the above step may be a transport step that simply transports the work W.

[0025] A code is provided on a portion of the outer surface of each workpiece W in a position that allows it to be imaged from above. The code includes both barcodes and two-dimensional codes. Examples of two-dimensional codes include QR Code (registered trademark), Micro QR Code, Data Matrix (Data code), Veri Code, Aztec Code, PDF417, and Maxi Code. Two-dimensional codes are available in stack and matrix types, and this embodiment can be applied to either type of two-dimensional code. The code may be provided by printing or engraving directly on the workpiece W, or by printing on a label and then attaching it to the workpiece W; the means and method are not important.

[0026] (Read start trigger signal) The first to third optical information readers 1A, 1B, and 1C are wired to a programmable logic controller (PLC) 130 via signal lines 130a, but this is not limiting, and the first to third optical information readers 1A, 1B, and 1C and the PLC 130 may each have a built-in communication module, and the first to third optical information readers 1A, 1B, and 1C may be wirelessly connected to the PLC 130. The PLC 130 is a control device for sequentially controlling the transfer belt conveyor B and the first to third optical information readers 1A, 1B, and 1C, and a general-purpose PLC may be used.

[0027] During operation, the first to third optical information readers 1A, 1B, and 1C each receive a read start trigger signal, which specifies the timing for starting code reading, from the PLC 130 via the signal line 130a. The first to third optical information readers 1A, 1B, and 1C then acquire and decode the code image based on the read start trigger signal. The read result is then transmitted to the PLC 130 via the signal line 130a. Thus, during operation of the first to third optical information readers 1A, 1B, and 1C, the read start trigger signal is repeatedly input and the decoded result is repeatedly output via the signal line 130a between the first to third optical information readers 1A, 1B, and 1C and an external control device such as the PLC 130. The read start trigger signal may be input and the read result may be output via the signal line 130a between the optical information readers 1A, 1B, and 1C and the PLC 130, as described above, or via other signal lines (not shown). For example, a sensor for detecting the arrival of the work W may be directly connected to the first to third optical information reading devices 1A, 1B, and 1C, and a 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 optical information reader) The first to third optical information readers 1A, 1B, and 1C are all the same. The configuration of the first optical information reader 1A will be described below. FIG. 2 is a block diagram of the first optical information reader 1A, and FIGS. 3 to 6 are diagrams showing the appearance of the first optical information reader 1A. The first optical information reader 1A includes a housing 2, an illumination unit 4, a camera 5, and a processor 20. The illumination unit 4 is a unit that illuminates the workpiece W, and the camera 5 is a unit that photographs the workpiece W, to which a code has been applied, while 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 a decoding means that decodes the code image acquired by the camera 5.

[0029] In the description of this embodiment, the up / down, left / right, and front / rear directions of the optical information reader 1 are defined as shown in Figures 3 to 6, but this is for convenience of description only and does not limit the orientation of the optical information reader 1 when in use. That is, as shown in Figure 1, the optical information reader 1A can be installed and used with its front surface (front face) facing downward and its rear surface (rear face) facing upward, or it can be installed and used with its front surface facing upward, or it can be installed and used with its front surface tilted. The left / right direction of the optical information reader 1A can also be called the width direction.

[0030] 3 to 6, the housing 2 has a generally 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, a top surface 2e, and a bottom surface 2f. When a first imaginary line L1 is a straight line extending vertically through the center of the front surface 2a of the housing 2 in the horizontal direction in the front view shown in FIG. 3 and a second imaginary line L2 is a straight line extending horizontally through the center of the front surface 2a of the housing 2 in the vertical direction in the front view shown in FIG. 3, the intersection of the first imaginary line L1 and the second imaginary line L2 is the center C of the front surface 2a of the housing 2. The first imaginary line L1 and the second imaginary line L2 are perpendicular to each other.

[0031] The camera 5, also shown in FIG. 7, is provided within the housing 2. As shown in FIG. 2, the camera 5 includes an imaging element 5a that captures an image of the code illuminated by the illumination unit 4, an optical system 5b including lenses, and an AF module (autofocus module) 5c. Light reflected from the code-bearing portion of the workpiece W is incident on the optical system 5b. The imaging element 5a is an image sensor including a photodetector such as a CCD (charge-coupled device) or a CMOS (complementary metal oxide semiconductor) that converts the image of the code obtained through the optical system 5b into an electrical signal. The imaging element 5a is connected to the processor 20, and the electrical signal converted by the imaging element 5a is input to the processor 20. The AF module 5c is a mechanism for adjusting the focus by changing the position and refractive index of the focusing lens that constitutes the optical system 5b. The AF module 5c is also connected to and controlled by the processor 20.

[0032] The camera 5 is housed within the housing 2 and fixed to the housing 2. The optical system 5b of the camera 5 is disposed so as to face the outside through a photographic window 2g (shown in FIG. 3, etc.) formed on the front surface 2a of the housing 2. The optical axis X1 of the optical system 5b extends in the front-to-rear direction of the housing 2. In a front view, the camera 5 is disposed offset from the center C of the housing 2. In other words, the optical axis X1 of the optical system 5b is spaced a distance D1 above the center C of the housing 2. The mounting position of the camera 5 within 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 illumination unit 4 is provided around the camera 5 inside the housing 2 and has multiple groups of light-emitting elements, such as light-emitting diodes, for illuminating the outside. As also shown in FIG. 7, the illumination unit 4 of this embodiment has a first group (first illumination group) 4a consisting of two light-emitting elements, a second group (second illumination group) 4b consisting of more than two light-emitting elements, and a third group (third illumination group) 4c consisting of two light-emitting elements. As will be described in detail later, the first group 4a provides unpolarized and non-diffuse illumination, the second group 4b provides unpolarized and diffuse illumination, and the third group 4c provides undiffuse and polarized illumination. The illumination unit 4 may also be configured with a polarized illumination group and a diffuse illumination group, and this configuration is also included in the present invention.

[0034] As described above, the first group 4a and the second group 4b have different numbers of light-emitting elements. Specifically, the number of light-emitting elements is set so that the second group 4b, which provides diffuse lighting, has a larger number of light-emitting elements than the first group 4a, which provides non-diffuse lighting. This makes it possible to irradiate a wide area with diffuse lighting. Note that the number of light-emitting elements is an example, and the first group 4a and the third group 4c may each be composed of three or more light-emitting elements.

[0035] The illumination intensity per light-emitting element in the first group 4a may be different from the illumination intensity per light-emitting element in the second group 4b. Specifically, the light-emitting elements are selected or controlled so that the illumination intensity per light-emitting element in the second group 4b is higher than that in the first group 4a. The size of each light-emitting element in the first group 4a may be different from that of each light-emitting element in the second group 4b. Specifically, the light-emitting elements are selected so that the size of each light-emitting element in the first group 4a is larger than that of the second group 4b. The color of the light-emitting elements in the first group 4a may be different from that of the second group 4b. For example, the color of the light-emitting elements in the first group 4a may be red, and the color of the light-emitting elements in the second group 4b may be blue, but this is not limited to this. Furthermore, the color of the light-emitting elements in the third group 4c may be different from that of the second group 4b. The color of the light-emitting elements in the third group 4c may be the same as that of the light-emitting elements in the first group 4a, specifically red. Furthermore, 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, the 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. The light-emitting elements constituting the second group 4b are disposed below the camera 5 on the substrate 4d. The area in which the light-emitting elements constituting the second group 4b are disposed is wider than the area in which 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 in the center of the area in which the light-emitting elements constituting the second group 4b are disposed.

[0037] The two light-emitting elements constituting the first group 4a are disposed on the substrate 4d, one on the left side and one on the right side of the camera 5. The optical axis X3 of the first group 4a is located between the two light-emitting elements constituting the first group 4a, and in this embodiment, 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, so the optical axis X3 is located in the center between the left light-emitting element and the right light-emitting element of the first group 4a.

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

[0039] The distance from the optical axis X1 of the camera 5 to the optical axis X2 of the second group 4b in a front view is set to be longer than the distance from the optical axis X1 of the camera 5 to the optical axis X4 of the third group 4c in a front view. In other words, by arranging direct lighting (or polarized lighting) and diffuse lighting on either side of the optical axis X1 of the camera 5, the optical axis X4 is offset from the center C of the front surface 2a of the housing 2, thereby making it possible to increase the area of ​​the diffuse lighting. In this embodiment, the polarized lighting and diffuse lighting are configured as described above.

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

[0041] The optical information reading device 1A is equipped with an aimer 10 composed of a light-emitting element such as a light-emitting diode. This aimer 10 indicates the position of the field of view of the camera 5 and the optical axis of the illumination unit 4 by emitting light forward of the optical information reading device 1A. A user can also set up the optical information reading device 1A by referring to the light emitted from the aimer 10. The aimer 10 is provided above the optical axis X1 of the camera 5, i.e., on the side where the camera 5 is offset from the center C of the housing 2. In addition, the aimer 10 is disposed between two light-emitting elements that make up the third group 4c of the illumination unit 4, and the aimer light is emitted from between these two light-emitting elements.

[0042] A polarizing plate 50, a diffuser plate 51, and a light-transmitting plate 52 are provided on the front surface 2a of the housing 2. That is, as shown in Fig. 8, which shows only the front surface 2a of the housing 2, a first light-projecting window 2h is formed on the front surface 2a of the housing 2 in front of the light-emitting elements that make up the third group 4c of the illumination unit 4. Since the light-emitting elements that make up the third group 4c are arranged so as to sandwich the camera 5 in the left-right direction, the two first light-projecting windows 2h are formed so as to sandwich the shooting window 2g in the left-right direction. The size of each of the first light-projecting windows 2h is set smaller than the size of the shooting window 2g.

[0043] Furthermore, a second light projection window 2i is formed in front of the second group 4b of the illumination 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 area where the light-emitting elements constituting the second group 4b are arranged, occupying, for example, at least 1 / 2 or 2 / 5 of the total area of ​​the front surface 2a. On the other hand, the third light projection window 2j is a smaller window than the second light projection window 2i to correspond to the area where the two light-emitting elements constituting the first group 4a are arranged, occupying at most 1 / 2 or 1 / 3 of the size of the second light projection window 2i. Because the two light-emitting elements constituting the first group 4a are spaced apart in the left-right direction, the third light projection window 2j has a shape elongated in the left-right direction. Furthermore, because an aimer 10 is arranged between the two light-emitting elements constituting the first group 4a, the aimer light emitted from the aimer 10 passes through the third light projection window 2j and is irradiated to the outside. Moreover, the area of ​​second light-emitting window 2i is set to be larger than the combined area of ​​two first light-emitting windows 2h.

[0044] The polarizing plates 50 are provided in front of the third group 4c so as to face the outside from each of the two first light projection windows 2h. In Fig. 8, the area in which the polarizing plates 50 are provided is indicated by diagonal lines extending diagonally downward to the left. The polarizing plates 50 have a polarizing effect.

[0045] The diffusers 51 are provided in front of the second group 4b so as to face the outside from the second light projection window 2i. In FIG. 8, the area where the diffusers 51 are provided is indicated by diagonal lines extending diagonally downward to the right. The diffusers 51 are configured to diffuse and emit light incident from the second group 4b. For example, the diffusers 51 are translucent plates with fine graining on the surface of the diffusers 51. The diffusers 51 do not have a polarization effect. Because the area of ​​the second light projection window 2j is larger than that of the third light projection window 2j, the area of ​​the diffusers 51 is larger than that of the translucent plates 52. The diffusers 51 are provided on the side of the front surface 2a of the housing 2 where the camera 5 is not offset, i.e., below the center C of the housing 2. In this embodiment, the upper part of the diffuser 51 reaches the center C of the housing 2, but the majority of the diffuser 51 is provided below the center C.

[0046] The light of the first group 4a is set to have a higher illuminance than the light of the second group 4b. Furthermore, the light irradiated from the first group 4a through the light-transmitting plate 52 is set to have a higher illuminance than the light irradiated from the second group 4b through the diffusion plate 51. This allows the workpiece W to be irradiated with strong, non-diffused light.

[0047] The light-transmitting plates 52 are provided so as to face the outside from the third light projection windows 2j, and are disposed in front of the first group 4a. The area in which the light-transmitting plates 52 are provided is indicated by cross-hatching in Fig. 8. As such, the light-transmitting plates 52 are provided on the opposite side of the diffuser plate 51 across the camera 5 when viewed from the front.

[0048] The illumination unit 4, the light-transmitting plate 52, and the diffusion plate 51 are asymmetric in either the vertical or horizontal direction when viewed from the front of the housing 2, but symmetric in the other direction when viewed from the front. Specifically, as shown in FIG. 3, the housing 2 is elongated in the vertical direction, and thus has a long axis in the vertical direction when viewed from the front. The long axis is a first virtual line L1, and the short axis is a second virtual line L2. In this case, the illumination unit 4, the light-transmitting plate 52, and the diffusion plate 51 are symmetric (symmetric in the horizontal direction) about the first virtual line L1. For example, the two light-emitting elements constituting the first group 4a of the illumination unit 4 are equidistant from the first virtual line L1 when viewed from the front, and are also positioned at the same vertical position. Similarly, the two light-emitting elements constituting the third group 4c of the illumination unit 4 are equidistant from the first virtual line L1 when viewed from the front, and are also positioned at the same vertical position. In addition, the number of light-emitting elements constituting the second group 4b of the lighting unit 4 is the same as the number of elements arranged to the left of the first virtual line L1 when viewed from the front, and the same positions in the vertical direction.

[0049] On the other hand, 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, so that the second virtual line L2 is asymmetric (asymmetric in the vertical direction).

[0050] The housing 2 may have a shape in which the long axis extends in the left-right direction and the short axis extends in the up-down direction. In this case, the illumination unit 4, the light-transmitting plate 52, and the diffusion plate 51 are symmetrical about the short axis, but are asymmetrical about the long axis.

[0051] In this embodiment, the polarizing plate 50, the diffuser plate 51, and the light-transmitting plate 52 are fixed to the front surface 2a of the housing 2. However, this is not limiting, and at least one of the polarizing plate 50, the diffuser plate 51, and the light-transmitting plate 52 may be detachably attached to the housing 2. Although not shown, for example, at least one of the polarizing plate 50, the diffuser plate 51, and the light-transmitting plate 52 may be integrated with a frame to form an attachment, and the frame may be attached to the front surface 2a of the housing 2 using, for example, a fastening structure such as a claw-fitting structure or a screw. In this case, at least one of the polarizing plate 50, the diffuser plate 51, and the light-transmitting plate 52 can be attached or detached as needed. The attachment may include only the diffuser plate 51, or may include only the polarizing plate 50, or may include both the diffuser plate 51 and the polarizing plate 50.

[0052] By providing the light-transmitting plate 52 above the camera 5 rather than to the side of it, it can be spaced apart from the camera 5. This makes it difficult for specularly reflected light to enter the camera 5, allowing a good code image to be acquired. Furthermore, by providing the light-transmitting plate 52 above, it is possible to separate the light-transmitting plate 52 from the diffusion plate 51. This makes it easier to achieve lighting that projects diffused lighting onto the back of the code.

[0053] (Diffusion plate molding) 9A and 9B show a diffuser unit 51A. The diffuser unit 51A is obtained by integrally molding a diffuser 51, a first lens 56, a second lens 57, and an aimer 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 secured over a wide range. The aimer lens 58 is disposed in front of the aimer 10. Since the diffuser 51 and the lenses 56, 57, and 58 are integrally molded, the number of parts can be reduced and the structure can be simplified. The diffuser 51 and the lenses 56, 57, and 58 may be configured as separate parts.

[0054] Furthermore, because light-emitting elements have wire bonding and patterns on the light source, unevenness in the amount of light can occur on the projection surface when the light from a single light-emitting element is collected and projected using a lens. In this embodiment, to avoid this unevenness in the amount of light, multiple pairs of light-emitting elements and lenses are installed, and they are mounted so that they do not face the same direction relative to the center of the optical axis of the light-emitting element. This reduces unevenness in the amount of light overall.

[0055] (Lighting control unit) 2, the first group 4a, the second group 4b, and the third group 4c are connected to a processor 20 and controlled by an illumination control unit 21 configured by the processor 20. The illumination control unit 21 can control the illumination unit 4 so that when the light-emitting elements of the second group 4b are turned on, the light-emitting elements of the other lighting groups 4a and 4c are not turned on; when the light-emitting elements of the first group 4a are turned on, the light-emitting elements of the other lighting groups 4b and 4c are not turned on; and when the light-emitting elements of the third group 4c are turned on, the light-emitting elements of the other lighting groups 4a and 4b are not turned on. In other words, the illumination control unit 21 is configured to be able to switch between direct light (light transmitted through the light-transmitting plate 52), diffused light, and polarized light to illuminate the code.

[0056] Here, capturing a code image using diffuse lighting will be described with reference to the schematic diagram shown in FIG. 10. When diffuse lighting is emitted from the second group 4b of the lighting unit 4 and directed onto a workpiece W bearing a code, the diffuse lighting is projected onto the back of the code, enabling a high-contrast code image to be captured. To project the diffuse lighting onto the back of the code, for example, a 20-mm square diffuse lighting unit is required when a 10-mm square code is being photographed. In other words, the diffuse lighting must be projected onto an area four times the area of ​​the code. In this embodiment, the diffuser plate 51 is larger than the light-transmitting plate 52 and the polarizer plate 50 and is provided over a wide area on the front surface 2a of the housing 2. This allows the diffuse lighting to be projected over a wide area required to project the diffuse lighting onto the back of the code.

[0057] Furthermore, for workpieces W that do not require diffused light, switching to direct light allows the code to be illuminated with a large amount of light, resulting in a high-contrast code image. Furthermore, switching to polarized light, if necessary, also allows a high-contrast code image to be obtained. This expands the range of workpieces W that can be read.

[0058] (Decoding process) The processor 20 constitutes a decoding unit 22. The decoding unit 22 decodes a code image acquired by the camera 5 when the light from the first group 4a is irradiated onto the code via the light-transmitting plate 52, a code image acquired by the camera 5 when the light from the second group 4b is irradiated onto the code via the diffusion plate 51, and a code image acquired by the camera 5 when the light from the third group 4c is irradiated onto the code via the polarizing plate 50. The code images are stored in the image data storage unit 30a of the storage unit 30 shown in FIG. 2.

[0059] The decoding unit 22 performs image processing using various image processing filters before decoding the code image. Then, during decoding, conventionally known tables can be used. Furthermore, the decoding unit 22 checks whether the decoded result is correct according to a predetermined check method. If an error is found in the data, the decoding unit 22 calculates the correct data using an error correction function. The error correction function differs depending on the type of code. The decoding unit 22 stores the decoded result obtained by decoding the code in the decoded result storage unit 30b of the storage unit 30.

[0060] (main unit display) As shown in FIG. 5, a main body display unit 6 is provided on the top surface 2e of the housing 2. The main body display unit 6 is, for example, an organic EL display or a liquid crystal display. 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, character strings resulting from 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 a reading process is performed multiple times. The matching level is a reading margin that indicates the ease of reading a successfully decoded code. This can be calculated from the number of error corrections made during decoding, and can be expressed, for example, as a numerical value. The fewer the error corrections, the higher the matching level (reading margin), and conversely, the more the error corrections, the lower the matching level.

[0061] (Operation buttons) A select button 11 and an enter button 12, which are used when setting up the optical information reader 1A, are provided on the top surface 2e of the housing 2. The select button 11 and the enter button 12 are connected to the processor 20, which is capable of detecting the operation states of the select button 11 and the enter button 12. The select button 11 is a button that is operated when selecting one option from multiple options displayed on the main body display unit 6. The enter button 12 is a button that is operated when confirming the result selected with the select button 11.

[0062] (indicator) An indicator 9 is also provided on the top surface 2e of the housing 2. The indicator 9 is connected to the processor 20 and can be configured with a light-emitting element 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) A rotary connector 60 is provided at the bottom of the housing 2. The rotary connector 60 is attached to the main body of the housing 2 so as to be rotatable around a center line L3 shown in Fig. 5. The rotary connector 60 is provided with a power connector 7 to which power wiring for supplying power to the optical information reader 1A is connected, and an Ethernet connector 8 to which the setting device 100 and the PLC 130 are connected. Note that the Ethernet standard is just an example, and signal lines of standards other than the Ethernet standard can also be used.

[0064] By rotating the rotary connector 60, it is possible to switch between a position in which the power connector 7 and the Ethernet connector 8 protrude downward from the housing 2 as shown in Figures 3 to 5, and a position in which the power connector 7 and the Ethernet connector 8 protrude rearward from the housing 2 as shown in Figure 6. Depending on the installation location of the optical information reading device 1A, the rotary connector 60 can be rotated to make the power connector 7 and the Ethernet connector 8 protrude in a desired direction.

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

[0066] (Configuration of 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 display) 1, the setting device 100 includes a display 101, but the display 101 may be a part of the first optical information reading device 1A. In this case, the optical information reading device may include an optical information reading device main body having a housing 2, an illumination unit 4, a camera 5, a light-transmitting plate 52, a diffusion plate 51, and a processor 20, and the display 101.

[0068] (tuning) The tuning execution unit 23 is configured by the processor 20 shown in FIG. 2. After activating the AF module 5c to adjust focus, the tuning execution unit 23 repeatedly captures and decodes the code by changing the shooting conditions of the camera 5 and the decoding conditions of the decoding process, and executes tuning processing to determine optimal shooting and decoding conditions based on a matching level indicating the ease of code reading (decoding margin) calculated under each shooting and decoding condition. For example, when setting up the optical information reading device 1A, the tuning execution unit 23 sets various conditions (tuning parameters) to achieve optimal decoding conditions by changing shooting conditions such as the gain of the camera 5, the light intensity of the illumination unit 4, lighting switching (switching between direct light, diffuse light, and polarized light), and exposure time, as well as image processing conditions. The image processing conditions include the coefficients (filter strength) of the image processing filter for the code image before decoding, switching between image processing filters if multiple image processing filters are available, and combinations of different types of image processing filters. Appropriate photographing conditions and image processing conditions vary depending on the effect of external light on the workpiece W during transport, the color and material of the surface to which the code is attached, etc. Therefore, the tuning execution unit 23 searches for more appropriate photographing conditions and image processing conditions and sets the above conditions.

[0069] 14, in step SB1 after the start, the tuning execution unit 23 controls the illumination unit 4 and camera 5 to cause the camera 5 to generate a code image, and the tuning execution unit 23 acquires the code image. At this time, decoding process parameters related to the presence and type of image processing filter to be executed before decoding, lighting conditions, shooting conditions, etc. are set to arbitrary parameters. Next, the process proceeds to step SB2, where the tuning execution unit 23 causes the decoding unit 22 to execute decoding process on the acquired code image.

[0070] After the decoding process, the process proceeds to step SB3, where the tuning execution unit 23 determines whether the decoding process of step SB2 was successful. If the determination in step SB3 is NO and the decoding process of step SB2 has failed, that is, if the code could not be read, the process proceeds to step SB4, where the decoding process parameters are changed to other parameters, and the decoding process is executed again in step SB2. If the decoding process has failed with all of the decoding process parameters, this flow ends and a notification is given to the user.

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

[0072] In step SB6, it is determined whether the decoding process has been completed for all the decoding process parameters. If the determination in step SB6 is NO, meaning that the decoding process has not been completed for all the decoding process parameters, the process proceeds to step SB7, where the decoding process parameters are changed to other parameters and the decoding process is performed again.

[0073] On the other hand, if step SB7 returns YES and the decoding process is completed for all the decoding process parameters, the process proceeds to step SB8. In step SB8, tuning execution unit 23 selects the decoding process parameter with the highest read 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 operating the optical information reading device 1A, it is possible to set which lighting group to use from the first to third groups 4a, 4b, and 4c of the lighting unit 4. The lighting group to use may be set by the tuning described above, or may be set to be the lighting group selected by the user. For example, a user interface that allows selection of the first to third groups 4a, 4b, and 4c may be generated and displayed on the display 101, and the user may select the desired lighting group by operating the keyboard 102 or mouse 103, so that the selection result is reflected during operation.

[0075] A parameter set is a set of parameters that constitute various conditions set as a result of tuning performed by the tuning execution unit 23 or various conditions set by the user. This parameter set is also the reading condition that is applied when decoding a code image. A parameter set can also be called a bank, and in this embodiment, multiple parameter sets can be stored. The reading condition that is applied when decoding the code image and the read data are associated and stored in the parameter set storage unit 30c.

[0076] This optical information reading device 1A is configured to be able to switch from one parameter set to another among the multiple parameter sets stored in the parameter set storage unit 30c. The parameter set can be switched by the user, or can be configured to be switched by a switching signal from an external control device such as the PLC 130. The user can switch the parameter set by operating the setting device 100 or the operation buttons 11 and 12. The selected parameter set is used when the optical information reading device 1A is operated, and the parameter sets that are not selected are not used when the optical information reading device 1A is operated. In other words, 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 screens can be generated by the control unit 105 of the setting device 100, for example.

[0078] FIG. 15 shows an example of a first user interface screen 300 displayed on the display device 101. The first user interface screen 300 is a screen for extracting records having the same read data from multiple optical information readers 1A, 1B, and 1C (referred to simply as readers 1A, 1B, and 1C in the figure) and displaying code images, read times, various conditions, and the like. The header section 301 of the first user interface screen 300 allows for the setting of filter / search conditions, and includes a filter setting area 301a, a search setting area 301b, a reader selection area 301c, and a period specification area 301d. The filter setting area 301a allows for the setting of conditions for selecting records to be displayed on the first user interface screen 300 from among a large number of records. Conditions such as "display all" and "display only errors" can be set. An error refers to a record that cannot be read or has failed to be read. The search setting area 301b allows for the setting of conditions for searching for a record having specified read data from among the records to be displayed. 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 reader to be displayed below the header section 301 is selected from among the plurality of optical information readers 1A, 1B, and 1C. For example, the first to third optical information readers 1A, 1B, and 1C that exist on the same network N are searched for, and the IP addresses of the searched optical information readers are obtained. Then, when the user operates the reader selection area 301c to select one of the first to third optical information readers 1A, 1B, and 1C, the control section 105 detects the selection operation and selects one of the first to third optical information readers 1A, 1B, and 1C.

[0080] Below the header section 301 of the first user interface screen 300, there is provided a reader display area 302 and a record display area 303 that displays a list of read data. The reader display area 302 displays information about the selected optical information reader. In this example, first to third optical information readers 1A, 1B, and 1C are displayed, but if only one is selected, it is also possible to display only that one. The reader display area 302 is provided with a first area 302a that displays information about the optical information reader, such as the name and model to identify the optical information reader, and an illustration or photo showing the appearance of the optical information reader. The control unit 105 displays information about the selected optical information reader in the first area 302a. Since it is 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] The reader display area 302 also has a second area 302b that displays a code image captured by an optical information reader. The reader display area 302 also has a third area 302c that displays the matching level (MLV) and the decoding time (hours) when the code is decoded by the optical information reader.

[0082] Below the reader display area 302, there are provided 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 that displays the applied image processing filter, and the like.

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

[0084] 16 shows an example of a second user interface screen 320. This second user interface screen 320 is provided with a code image display area 321, a first area 322 that displays a code image acquired by irradiating the code with polarized light, a second area 323 that displays a code image acquired by irradiating the code with direct light, and a third area 324 that displays a code image acquired by irradiating the code with diffused light. The second user interface screen 320 can display the code image acquired by irradiating the code with polarized light, the code image acquired by irradiating the code with direct light, and the code image acquired by irradiating the code with diffused light in a comparative manner, allowing the user to determine which lighting is appropriate while viewing the actual images.

[0085] (Effects of the embodiment) As described above, in 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 diffuser plate 51 is provided in front of the second group 4b. Therefore, light from the second group 4b is diffused by the diffuser plate 51 before being irradiated onto the code. The diffuser plate 51 is larger than the light-transmitting plate 52, through which the light from the first group 4a passes. This allows the diffused light to be irradiated over a wide area, i.e., an area four times the size of the code. This allows the camera 5 to capture a high-contrast code image even if the surface of the workpiece W is mirror-finished. As a result, the reading success rate can be increased.

[0086] On the other hand, the light from the first group 4a passes through the light-transmitting plate 52 before being irradiated onto the code. The amount of light that passes through the light-transmitting plate 52 is greater than when it passes through the diffuser plate 51, so even workpieces that are difficult to read with diffused lighting can be read with a sufficient amount of light, expanding the range of codes that can be read.

[0087] The above-described embodiments are merely examples in all respects and should not be construed as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0088] As described above, the optical information reader according to the present invention can be used to read codes such as two-dimensional codes. [Explanation of symbols]

[0089] 1A First optical information reader 2. Case 2a Front (first side) 4. Lighting section 4a Group 1 4b Group 2 4c Group 3 5. Camera 21 Lighting control unit 22 Decoding section 50 Polarizing Plate 51 Diffuser 52 Translucent plate 101 Display

Claims

[Claim 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 reader includes: a diffused lighting unit that irradiates diffused light onto the coded workpiece; a direct lighting unit that irradiates the workpiece with direct light having a narrower irradiation range than the diffused light; a polarized illumination unit that irradiates the workpiece with polarized light having a narrower illumination range than the diffused light; a camera that photographs the workpiece and acquires a code image including the code; a processor that controls any one of the diffused lighting unit, the direct lighting unit, and the polarized lighting 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 on a display at least one of a diffuse light image acquired by the camera by irradiating the diffuse light, a direct light image acquired by the camera by irradiating the direct light, and a polarized light image acquired by the camera by irradiating the polarized light, in association with information from the corresponding lighting unit.

Images