JP7653345B2 - Optical information reader - Google Patents

Description

This disclosure relates to a fixed optical information reading device that reads a code attached to a workpiece.

Optical information reading devices include handheld types that are held in the hand and used, and fixed types that are installed on a factory line or the like and used in a fixed state. Fixed type optical information reading devices are disclosed, for example, in Patent Documents 1 and 2. The optical information reading device of Patent Document 1 is equipped with a first illumination unit that irradiates the workpiece with illumination light through a polarizing filter, and a second illumination unit that irradiates the workpiece with illumination light without passing through a polarizing filter. The optical information reading device of Patent Document 2 is equipped with a diffuse reflection member that diffuses and reflects the light that is emitted from the illumination unit and specularly reflected by the surface of the workpiece.

JP 2016-33787 A JP 2016-218588 A

When photographing a code, if the surface of the workpiece on which the code is applied is mirror-finished, the contrast of the code image may be low, making it difficult to read the code. Therefore, when photographing such a mirror-surfaced workpiece, diffuse lighting is used and the diffuse lighting is shone on the background of the code, making it possible to obtain a code image with high contrast.

However, to obtain a high-contrast code image using diffuse lighting, it is necessary to illuminate 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, with diffuse light. On the other hand, 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 diffuse lighting that can illuminate a wide area.

In addition, because diffuse lighting diffuses light, the amount of light is insufficient, which can reduce the contrast of the code image and make it difficult to read the code, so if only diffuse lighting is installed, the reading range will be narrow.

The present disclosure has been made in consideration of these points, and its purpose is to enable wide-area illumination with diffuse lighting while miniaturizing the housing, and to expand the range of compatibility with various workpieces by making it possible to read workpieces that are difficult to read with diffuse lighting with powerful lighting.

In order 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 for photographing a workpiece to which a code has been applied and acquiring a code image including the code, a lighting unit provided around the camera in the housing and having light-emitting elements for irradiating light to the outside, and including a plurality of groups, a light-transmitting plate provided on a first surface of the housing and positioned in front of the first lighting group, a diffusion plate provided on the first surface of the housing and positioned in front of the second lighting group, and having an area larger than that of the light-transmitting plate, and a decoding means for decoding the code image acquired by the camera by irradiating the code with light from the first lighting group through the light-transmitting plate and the code image acquired by the camera by irradiating the code with light from the second lighting group through the diffusion plate.

With this configuration, the light from the second lighting group is diffused by the diffuser plate before being irradiated onto the code. The diffuser plate is larger than the light-transmitting plate through which the light from the first lighting group passes, making it 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 has a mirror-like surface.

Meanwhile, the light from the first lighting group passes through a translucent plate before being irradiated onto the code. The amount of light that passes through the translucent plate can be greater than that when it passes through a diffuser plate, so even work that is difficult to read with diffuse lighting can be read with a sufficient amount of light, expanding the range of codes that can be read. The translucent plate and diffuser plate can be attached removably to the housing.

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 provided in front of the second lighting group larger.

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, allowing for more diverse lighting and further expanding the range of readings.

The lighting unit according to another aspect has a third lighting group and is provided with a polarizing plate in front of this third lighting group, so that it is also possible to emit polarized light. The polarizing plate can be removably attached to the housing.

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

In another aspect, the device may be configured to include a polarizing plate provided on the first surface of the housing and positioned in front of the third lighting group, a diffusing plate provided on the first surface of the housing and positioned in front of the second lighting group, the diffusing plate having a larger area than the polarizing plate, and a decoding means for decoding a code image captured by a camera by irradiating the code with light from the third lighting group through the polarizing plate, and a code image captured by the camera by irradiating the code with light from the second lighting group through the diffusing plate.

As explained above, it is possible to miniaturize the housing while enabling wide-area illumination with diffuse lighting, and it is also possible to read even workpieces that are difficult to read with diffuse lighting, expanding the range of application.

FIG. 2 is a diagram illustrating the optical information reader during operation. FIG. 1 is a block diagram of an optical information reader. FIG. 2 is a front view of the optical information reader. FIG. 2 is a perspective view of the optical information reader as seen from the connector side. FIG. 2 is a perspective view of the optical information reader as viewed from the rear side. FIG. 13 is a perspective view showing a state in which the connector is rotated. FIG. 2 is a perspective view showing the internal structure of the optical information reader. FIG. 2 is a front view showing the structure of the front surface of the housing. FIG. FIG. 2 is a perspective view of a diffusion plate unit. FIG. 13 is a diagram showing a schematic diagram of capturing a code image with diffuse illumination. FIG. 13 is a front view of an optical information reader not equipped with a connector rotation mechanism. 11 is a perspective view of an optical information reader not having a connector rotation mechanism, as viewed from the connector side. FIG. 11 is a perspective view of an optical information reader not having a connector rotation mechanism, as viewed from the rear side. FIG. 13 is a flowchart showing an example of a tuning procedure performed by a tuning execution unit. FIG. 13 is a diagram illustrating an example of a first user interface screen. FIG. 13 is a diagram illustrating an example of a second user interface screen.

The following describes in detail an embodiment of the present invention with reference to the drawings. Note that the following description of the preferred embodiment is essentially merely an example and is not intended to limit the present invention, its applications, or its uses.

Figure 1 is a schematic diagram showing optical information reading devices 1A, 1B, and 1C according to an embodiment of the present invention during operation, and an optical information reading system S including those optical information reading devices 1A, 1B, and 1C and a setting device 100 during operation. 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 multiple number. In the example shown in Figure 1, three optical information reading devices are provided: a first optical information reading device 1A, a second optical information reading device 1B, and a third optical information reading device 1C.

The setting device 100 can be a general-purpose or dedicated electronic computer, a portable terminal, or the like, and is equipped with 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 memory unit 106. The keyboard 102 and the mouse 103 are operation devices for the user to operate the setting device 100. By operating the keyboard 102 and the mouse 103, it is possible to input any number, etc., and to perform various settings, etc. 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 memory unit 106 stores the operating program, imaging conditions, reading conditions, code images, reading results, etc. of the optical information reading system S.

In the example shown in FIG. 1, multiple workpieces W are placed on the top surface of the transport belt conveyor B and are transported in the direction of arrow Y in FIG. 1. The workpieces W are, for example, luggage, merchandise, various parts, electrical products, electronic devices, and other items, and a first process is carried out on the workpieces W at the most upstream position in the transport direction of the belt conveyor B, a second process is carried out on the same workpieces W at the middle position, and a third process is carried out on the same workpieces W at the most downstream position. At each process, for example, printing, pasting, installation of parts, various processing, painting, adjustment, etc. are carried out.

A first optical information reading device 1A is installed at a position 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). In addition, a second optical information reading device 1B is installed at a position 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 position above and away from the workpiece W placed on the belt conveyor B in the third process.

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) so that they do not move. The stationary first to third optical information readers 1A, 1B, and 1C may be used while being held by a robot (not shown). The code of a workpiece W in a stationary state may also be read by the first to third optical information readers 1A, 1B, and 1C. When the stationary first to third optical information readers 1A, 1B, and 1C are in operation, the code of the workpiece W transported by the transport belt conveyor B is read in sequence.

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 workpiece 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 there may be only one step. Furthermore, the above step may be a transport step that simply transports the workpiece W.

A code is provided on a portion of the outer surface of each workpiece W at a position that allows imaging 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 classified into stack type and matrix type, and this embodiment can be applied to any two-dimensional code. The code may be provided by directly printing or engraving on the workpiece W, or by printing on a label and then attaching it to the workpiece W, and the means and method are not important.

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

During operation, the first to third optical information readers 1A, 1B, and 1C each receive a read start trigger signal that specifies the start timing of 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. In this manner, 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. Note that 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 1 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.

(Configuration of the optical information reading device)
The first to third optical information reading devices 1A, 1B, and 1C are the same. The configuration of the first optical information reading device 1A will be described below. FIG. 2 is a block diagram of the first optical information reading device 1A, and FIGS. 3 to 6 are diagrams 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, a camera 5, and a processor 20. The illumination unit 4 is a part that illuminates the work W, and the camera 5 is a part that photographs the work W to which a code is given in a state illuminated by the illumination unit 4, and acquires a code image including the code. The decode unit 22 of the processor 20 is an example of a decode means that decodes the code image acquired by the camera 5.

In the description of this embodiment, the top, bottom, left, right, front and back of the optical information reading device 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 reading device 1 when in use. That is, as shown in Figure 1, the optical information reading device 1A can be installed and used with its front surface facing down and its rear surface facing up, or it can be installed and used with its front surface facing up, or it can be installed and used with its front surface tilted. The left-right direction of the optical information reading device 1A can also be called the width direction.

As shown in Figures 3 to 6, the housing 2 is in the shape of a generally rectangular box 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 virtual line L1 is a straight line extending in the vertical direction through the center of the front surface 2a of the housing 2 in the left-right direction in the front view shown in Figure 3, and a second virtual line L2 is a straight line extending in the horizontal direction through the center of the front surface 2a of the housing 2 in the vertical direction, 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 perpendicular to each other.

The camera 5, which is also shown in FIG. 7, is provided in the housing 2. As shown in FIG. 2, the camera 5 includes an image sensor 5a that captures an image of the code illuminated by the illumination unit 4, an optical system 5b having lenses and the like, and an AF module (autofocus module) 5c. The optical system 5b is configured to receive light reflected from the part of the workpiece W to which the code is attached. The image sensor 5a is an image sensor consisting 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 code 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. The AF module 5c is a mechanism that adjusts the focus by changing the position and refractive index of the focusing lens among the lenses that make up the optical system 5b. The AF module 5c is also connected to the processor 20 and is controlled by the processor 20.

The camera 5 is fixed to the housing 2 while being accommodated within the housing 2. The optical system 5b of the camera 5 is disposed so as to face the outside through a shooting 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 upward from the center C of the housing 2 by a distance D1. The mounting position of the camera 5 within the housing 2 is set so that the optical system 5b is positioned at this position.

3 and 7, the illumination unit 4 is provided around the camera 5 in the housing 2 and has light-emitting elements such as light-emitting diodes for irradiating the outside, and is divided into a plurality of groups. As shown in FIG. 7, the illumination unit 4 in 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 is non-polarized and non-diffuse illumination, the second group 4b is non-polarized and diffuse illumination, and the third group 4c is non-diffuse and polarized illumination. The illumination unit 4 may be composed of a polarized illumination group and a diffuse illumination group, and this form is also included in the present invention.

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 is diffuse lighting, has a greater number of light-emitting elements than the first group 4a, which is non-diffuse lighting. This makes it possible to irradiate a wide range with diffuse lighting. Note that the number of light-emitting elements is just an example, and the first group 4a and the third group 4c may be composed of three or more light-emitting elements.

The illumination intensity per light-emitting element of the first group 4a and the illumination intensity per light-emitting element of the second group 4b can be different. Specifically, the light-emitting elements are selected or controlled so that the illumination intensity per light-emitting element of the second group 4b is higher than that of the first group 4a. The size of each light-emitting element of the first group 4a and the size of each light-emitting element of the second group 4b can also be different. Specifically, the light-emitting elements are selected so that the size of each light-emitting element of the first group 4a is larger than that of the second group 4b. The color of the light-emitting element of the first group 4a and the color of the light-emitting element of the second group 4b can also be different. For example, the color of the light-emitting element of the first group 4a can be red, and the color of the light-emitting element of the second group 4b can be blue, but this is not limited to this. The light-emitting element of the third group 4c is a light-emitting element different from the light-emitting element of the second group 4b. The color of the light-emitting element of the third group 4c is the same as the color of the light-emitting element of the first group 4a, and specifically, can be red. Additionally, the light-emitting elements in the first group 4a and the light-emitting elements in the third group 4c can be the same.

As shown in FIG. 7, the multiple light-emitting elements constituting the first to third groups 4a, 4b, and 4c are mounted on the same board 4d. That is, this board 4d extends in the vertical and horizontal directions within the housing 2. The optical system 5b of the camera 5 is arranged so as to penetrate a portion offset upward from the center C of the housing 2. The multiple light-emitting elements constituting the second group 4b are arranged below the camera 5 on the board 4d. The area in which the light-emitting elements constituting the second group 4b are arranged is wider than the area in which the light-emitting elements constituting the first group 4a are arranged. 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 arranged.

The two light-emitting elements constituting the first group 4a are disposed on the substrate 4d, respectively to the left and right 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, 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, 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.

The two light-emitting elements constituting the third group 4c are disposed on the left and right sides of the substrate 4d 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.

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 can be offset with respect to the center C of the front surface 2a of the housing 2, thereby increasing the area of the diffuse lighting. In this embodiment, the polarized lighting and diffuse lighting are in the above-mentioned form.

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. Also, 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.

The optical information reading device 1A is equipped with an aimer 10 composed of a light-emitting body such as a light-emitting diode. This aimer 10 is intended to indicate the field of view of the camera 5 and the position of 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, that is, on the side where the camera 5 is offset from the center C of the housing 2. The aimer 10 is also disposed between two light-emitting elements that constitute the third group 4c of the illumination unit 4, and the aimer light is emitted from between these two light-emitting elements.

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 in FIG. 8, in front surface 2a of the housing 2, 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. Since the light-emitting elements constituting the third group 4c are arranged so as to sandwich the camera 5 in the left-right direction, the two first light projection windows 2h are formed so as to sandwich the shooting window 2g in the left-right direction. The size of each first light projection window 2h is set smaller than the size of the shooting window 2g.

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 area in which the light-emitting elements constituting the second group 4b are arranged, and occupies, for example, 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 smaller window than the second light projection window 2i so as to correspond to the area in which the two light-emitting elements constituting the first group 4a are arranged, and is 1/2 or less, or 1/3 or less in size than 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 shape that is long in the left-right direction. In addition, since the aimer 10 is arranged between the two light-emitting elements constituting the first group 4a, the aimer light irradiated from this aimer 10 passes through the third light projection window 2j and is irradiated to the outside. Additionally, 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.

The polarizing plates 50 are provided so that they 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 area in which the polarizing plates 50 are provided is indicated by diagonal lines extending diagonally downward to the left. The polarizing plate 50 has a polarizing effect.

The diffusion plates 51 are provided so as to face the outside from the second light projection window 2i, and are disposed in front of the second group 4b. In FIG. 8, the range in which the diffusion plates 51 are provided is indicated by a diagonal line extending diagonally downward to the right. The diffusion plate 51 is configured to diffuse the light incident from the second group 4b and emit it, and is, for example, a translucent plate with fine grain formed on the surface of the diffusion plate 51. This diffusion plate 51 does 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 plate 51 is larger than that of the translucent plate 52. The diffusion plate 51 is 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 plate 51 reaches the center C of the housing 2, but most of the diffusion plate 51 is provided below the center C.

The light of the first group 4a is set to have a higher illuminance than the light of the second group 4b. Also, 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.

The light-transmitting plates 52 are each provided so as to face the outside from the third light projection window 2j, and are disposed in front of the first group 4a. In FIG. 8, the range in which the light-transmitting plates 52 are provided is indicated by cross-hatching. In this way, 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.

The lighting 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, and are symmetric in either the vertical or horizontal direction when viewed from the front. Specifically, as shown in FIG. 3, the housing 2 has a long shape in the vertical direction, and therefore has a long axis in the vertical direction when viewed from the front. The long axis is the first virtual line L1, and the short axis is 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 equally distant from the first virtual line L1 when viewed from the front, and are also in the same position in the vertical direction. Similarly, the two light-emitting elements constituting the third group 4c of the lighting unit 4 are equally distant from the first virtual line L1 when viewed from the front, and are also in the same position in the vertical direction. In addition, the number of light-emitting elements constituting the second group 4b of the illumination unit 4 is the same as the number of light-emitting elements arranged to the left of the first virtual line L1 in front view and to the right of the first virtual line L1, and the positions in the up-down direction are also the same.

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).

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, and are asymmetrical about the long axis.

In this embodiment, the polarizing plate 50, the diffusing plate 51, and the light-transmitting plate 52 are fixed to the front surface 2a of the housing 2, but the present invention is not limited to this. At least one of the polarizing plate 50, the diffusing 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 diffusing plate 51, and the light-transmitting plate 52 may be integrated with the frame body as an attachment, 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 structure using screws or the like. In this case, at least one of the polarizing plate 50, the diffusing plate 51, and the light-transmitting plate 52 can be attached or detached as necessary. The attachment may have only the diffusing plate 51, may have only the polarizing plate 50, or may have both the diffusing plate 51 and the polarizing plate 50.

By placing the light-transmitting plate 52 above the camera 5 instead of to the side, it can be placed away from the camera 5. This makes it difficult for specularly reflected light to enter the camera 5, and a good code image can be obtained. Also, by placing 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 diffuse lighting onto the back of the code.

(Molding of the diffusion plate)
9A and 9B show the 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 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 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. The diffusion plate 51 and the lenses 56, 57, and 58 may be configured as separate parts.

In addition, 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 focused by a lens and projected. 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.

(Lighting control unit)
As shown in Fig. 2, the first group 4a, the second group 4b, and the third group 4c are connected to a processor 20 and are controlled by an illumination control unit 21 configured by the processor 20. The illumination control unit 21 is capable of controlling the illumination unit 4 so as not to light the light-emitting elements of the other illumination groups 4a and 4c when the light-emitting elements of the second group 4b are turned on, controlling the illumination unit 4 so as not to light the light-emitting elements of the other illumination groups 4b and 4c when the light-emitting elements of the first group 4a are turned on, and controlling the illumination unit 4 so as not to light the light-emitting elements of the other illumination groups 4a and 4b when the light-emitting elements of the third group 4c are turned on. In other words, the illumination control unit 21 is configured to be able to irradiate the code by switching between direct light (light transmitted through the light-transmitting plate 52), diffused light, and polarized light.

Here, the capturing of a code image using diffuse lighting will be described based on the schematic diagram shown in FIG. 10. When the diffuse lighting is emitted from the second group 4b of the lighting unit 4 and applied to the workpiece W to which the code is attached, the diffuse lighting is projected onto the back of the code, making it possible to obtain a code image with high contrast. In order to project the diffuse lighting onto the back of the code, for example, when a 10 mm square code is to be photographed, a 20 mm square diffuse lighting is required. In other words, it is necessary to project the diffuse lighting 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 polarizing plate 50 and is provided over a wide area on the front surface 2a of the housing 2, so that the diffuse lighting can be projected onto the wide area required to project the diffuse lighting onto the back of the code.

In addition, for workpieces W that do not require diffused light, switching to direct light allows a large amount of light to be irradiated onto the code, resulting in a high-contrast code image. Also, by switching to polarized light as necessary, a high-contrast code image can be obtained. This expands the range of workpieces W that can be read.

(Decoding process)
The processor 20 constitutes a decoding unit 22. The decoding unit 22 decodes a code image obtained by the camera 5 by irradiating the code with light from the first group 4a through the light-transmitting plate 52, a code image obtained by the camera 5 by irradiating the code with light from the second group 4b through the diffusion plate 51, and a code image obtained by the camera 5 by irradiating the code with light from the third group 4c through 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.

The decoding unit 22 performs image processing using various image processing filters and the like before decoding the code image. Thereafter, when decoding, a conventionally known table can be used. Furthermore, the decoding unit 22 checks whether the decoded result is correct or not according to a predetermined check method. If an error is found in the data, an error correction function is used to calculate the correct data. 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.

(Main unit display)
As shown in FIG. 5, a main display unit 6 is provided on the upper surface 2e of the housing 2. The main display unit 6 is, for example, an organic EL display or a liquid crystal display. As shown in FIG. 2, the main display unit 6 is connected to the processor 20. For example, the main display unit 6 can display a code image photographed by the camera 5, a character string resulting from decoding the code image, a reading success rate, a matching level, and the like. The reading success rate is an average reading success rate when a reading process is executed multiple times. The matching level is a reading margin indicating the ease of reading a successfully decoded code. This can be obtained from the number of error corrections that occur 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 on the other hand, the more the error corrections, the lower the matching level.

(Operation button)
A select button 11 and an enter button 12 are provided on the top surface 2e of the housing 2, which are used when setting up the optical information reader 1A, etc. 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.

(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 may 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.

(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 a power line for supplying power to the optical information reading device 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.

By rotating the rotating connector 60, it is possible to switch between a posture 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 posture 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 rotating connector 60 can be rotated to make the power connector 7 and the Ethernet connector 8 protrude in the desired direction.

(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, for example, 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.

(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.

(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 including 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.

(tuning)
The tuning execution unit 23 is configured by the processor 20 shown in FIG. 2. The tuning execution unit 23 performs a tuning process in which, after activating the AF module 5c to perform focusing, the shooting conditions of the camera 5 and the decode conditions of the decode process are changed, and the shooting and decode processes of the code are repeated, and the optimal shooting conditions and decode conditions are determined based on a matching level indicating the ease of reading the code (decode margin) calculated under each shooting condition and decode condition. For example, the tuning execution unit 23 is a part that sets various conditions (tuning parameters) when setting the optical information reading device 1A, such as the gain of the camera 5, the light amount of the illumination unit 4, illumination switching (switching between direct light, diffuse light, and polarized light), and exposure time, and image processing conditions, so as to obtain conditions suitable for decoding. The image processing conditions include the coefficients (strength and weakness of the filter) of the image processing filter for the code image before decoding, switching of the image processing filters when there are multiple image processing filters, 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 transportation, 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.

Specifically, as shown in the flowchart of FIG. 14, in step SB1 after starting, 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, the decode processing parameters related to the presence and type of image processing filter executed before the decode processing, the illumination conditions, the shooting conditions, etc. are set to arbitrary parameters. Next, the process proceeds to step SB2, where the tuning execution unit 23 causes the decode unit 22 to execute the decode processing on the acquired code image.

After the decoding process, the process proceeds to step SB3, where the tuning execution unit 23 determines whether the decoding process in step SB2 was successful. If the result of step SB3 is NO and the decoding process in step SB2 has failed, i.e., if the code cannot 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 the user is notified.

On the other hand, if step SB3 returns 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 results of the decoding process and temporarily stores the evaluation.

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.

On the other hand, if step SB7 returns YES and the execution of the decoding process is completed for 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.

In the tuning process, the lighting conditions are also set to appropriate conditions. That is, it is possible to set which lighting group of the first to third groups 4a, 4b, and 4c of the lighting unit 4 is to be used when the optical information reading device 1A is in operation. The lighting group to be used 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 operate the keyboard 102 or mouse 103 to select the desired lighting group, and the selection result may be reflected during operation.

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.

This optical information reading device 1A is configured to be able to switch from one parameter set to another of 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. When the user switches the parameter set, he or she operates 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 set that is not selected is 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.

(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.

Figure 15 shows an example of the 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 readers 1A, 1B, and 1C (simply referred to 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 filter/search conditions to be set, and includes a filter setting area 301a, a search setting area 301b, a reader selection area 301c, and a period designation area 301d. In the filter setting area 301a, conditions are set for selecting the object (display object) to be displayed on the first user interface screen 300 from among a large number of records, and conditions such as "display all" and "display only errors" can be set. An error is a record that cannot be read or has failed to be read. In the search setting area 301b, conditions can be set for searching for a record having the specified read data from among the records to be displayed. In the period specification area 301d, it is possible to specify the period for which the display target is to be extracted.

In the reader selection area 301c, the optical information reader to be displayed below the header section 301 is selected from among multiple optical information readers 1A, 1B, 1C. For example, the first to third optical information readers 1A, 1B, 1C that exist on the same network N are searched for, and the IP address of the searched optical information reader is obtained. Then, when the user operates the reader selection area 301c to select the first to third optical information readers 1A, 1B, 1C, the control section 105 detects the selection operation and selects the first to third optical information readers 1A, 1B, 1C.

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 reading device. In this example, the first to third optical information reading devices 1A, 1B, and 1C are displayed, but if only one is selected, it is also possible to display only one. The reader display area 302 is provided with a first area 302a in which the name, model, illustrations and photos showing the appearance of the optical information reading device, etc., for identifying the optical information reading device are displayed as information about the optical information reading device, and the control unit 105 causes the information about the selected optical information reading device to be displayed in the first area 302a. Since it is possible to determine the model, etc. from the appearance of the optical information reading device, it is easy to know which type of optical information reading device is installed in which process.

The reader display area 302 also includes a second area 302b in which the code image captured by the optical information reader is displayed. The reader display area 302 also includes a third area 302c in which the matching level (MLV) and the decoding time (hours) are displayed when the code is decoded by the optical information reader.

Below the reader display area 302 are 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.

The reading distance display area 304 displays the distance (reading distance) between the optical information reading device and the workpiece. The installation angle display area 305 displays the installation angle (tilt angle, pitch angle, etc.) of the optical information reading device. The bank information display area 306 displays the number of the bank (parameter set number) that was applied when the camera 5 acquired the code image and that successfully read it. The lighting information display area 307 displays lighting information indicating whether the lighting unit 4 irradiated direct light, diffused light, or polarized light when the camera 5 acquired the code image. The lighting information is information included in the parameter set. The lighting information displayed in the lighting 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 captured with direct light, the code image acquired by the second optical information reading device 1B is an image captured with diffused light, and the code image acquired by the third optical information reading device 1C is an image captured with polarized light.

Figure 16 shows an example of the 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 polarized light, a second area 323 that displays a code image acquired by irradiating direct light, and a third area 324 that displays a code image acquired by irradiating diffuse light. The second user interface screen 320 can display the code image acquired by irradiating polarized light, the code image acquired by irradiating direct light, and the code image acquired by irradiating diffuse light in a comparative manner, so that the user can determine which lighting is appropriate while looking at the actual images.

(Effects of the embodiment)
As described above, according to this embodiment, the illumination unit 4 has the first group 4a and the second group 4b, the light-transmitting plate 52 is provided in front of the first group 4a, and the 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. The diffusion plate 51 is larger than the light-transmitting plate 52 through which the light from the first group 4a passes, so that it is possible to irradiate the diffused light 51 over a wide area, that is, to irradiate an area four times the area of the code. As a result, even if the surface of the workpiece W is a mirror surface, a code image with high contrast is acquired by the camera 5. As a result, the reading success rate can be increased.

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 passing through the light-transmitting plate 52 is greater than when passing through the diffuser plate 51, so even for workpieces that are difficult to read with diffuse lighting, a sufficient amount of light is ensured and reading is possible, expanding the range of codes that can be read.

The above-described embodiments are merely illustrative in all respects and should not be interpreted as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention.

As described above, the optical information reading device according to the present invention can be used to read codes such as two-dimensional codes.

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 Decode unit 50 Polarizing plate 51 Diffusion plate 52 Light-transmitting plate 101 Display

Claims (18)

A housing and
a camera provided within the housing for photographing a workpiece having a code thereon and acquiring a code image including the code;
a lighting unit including a plurality of groups, the lighting unit being provided around the camera in the housing and having a light emitting element for emitting illumination to the outside;
a light-transmitting plate provided on a first surface of the housing and positioned in front of the first lighting group;
a diffuser disposed on the first surface of the housing and positioned in front of the second lighting group;
a decoding means for decoding a code image captured by the camera by irradiating the code with light from the first lighting group through the light-transmitting plate and a code image captured by the camera by irradiating the code with light from the second lighting group through the diffusion plate;
Equipped with
A fixed type optical information reader , wherein an area of the light exit region of the diffusion plate is larger than an area of the light exit region of the light-transmitting plate . 2. The optical information reading device according to claim 1,
An optical information reading device, wherein the distance from the optical axis of the camera to the optical axis of the second lighting group in a front view is set to be longer than the distance from the optical axis of the camera to the optical axis of the first lighting group in a front view. 3. The optical information reading device according to claim 1,
An optical information reading device in which the first lighting group and the second lighting group differ in at least one of the number of the light-emitting elements, the color of the light-emitting elements, the illumination intensity per light-emitting element, and the size of the light-emitting elements. 4. The optical information reading device according to claim 1,
An optical information reading device, wherein the light of the first lighting group is set to have a higher illuminance than the light of the second lighting group, or the light irradiated from the first lighting group through the light-transmitting plate is set to have a higher illuminance than the light irradiated from the second lighting group through the diffusion plate. 5. The optical information reading device according to claim 1,
When viewed from the front, the camera is disposed offset from the center of the housing;
An optical information reading device, wherein the diffusion plate is provided on the side of the first surface where the camera is not offset. 6. The optical information reading device according to claim 5,
An optical information reading device in which an aimer that emits light indicating the field of view of the camera is provided on the side where the camera is offset. 7. The optical information reading device according to claim 1,
An optical information reading device in which the illumination unit, the diffusion plate, and the light-transmitting plate are asymmetric in either the vertical or horizontal direction when viewed from the front, and symmetric in the other of the vertical or horizontal directions. 8. The optical information reading device according to claim 7,
The housing has a long axis in a vertical or horizontal direction when viewed from the front,
An optical information reading device, wherein the illumination unit, the diffusion plate, and the light-transmitting plate are symmetrical about the major axis. 9. The optical information reading device according to claim 1,
The lighting unit includes a third lighting group,
An optical information reading device comprising a polarizing plate in front of the third illumination group. A housing and
a camera provided within the housing for photographing a workpiece having a code thereon and acquiring a code image including the code;
a lighting unit including a plurality of groups, the lighting unit being provided around the camera in the housing and having a light emitting element for emitting illumination to the outside;
a polarizer provided on the first surface of the housing and positioned in front of the third lighting group;
a diffuser disposed on the first surface of the housing and positioned in front of the second lighting group;
a decoding means for decoding a code image acquired by the camera by irradiating the code with light from the third lighting group through the polarizing plate and a code image acquired by the camera by irradiating the code with light from the second lighting group through the diffusion plate;
Equipped with
A fixed type optical information reader , wherein an area of a light exit region of the diffusion plate is larger than an area of a light exit region of the polarizing plate . 11. The optical information reading device according to claim 10,
An optical information reading device, wherein the light emitting elements of the third lighting group are different from the light emitting elements of the second lighting group. 12. The optical information reading device according to claim 9,
The polarizing plate is provided on the opposite side of the diffusion plate with the camera therebetween when viewed from the front. 13. The optical information reading device according to claim 9,
An optical information reading device, wherein the distance from the optical axis of the camera to the center of the optical axis of the second lighting group in a front view is set to be longer than the distance from the optical axis of the camera to the center of the optical axis of the third lighting group in a front view. 14. The optical information reading device according to claim 1,
An optical information reading device comprising an illumination control unit that controls the illumination units so that when the light-emitting elements of the second illumination group are turned on, the light-emitting elements of the other illumination groups are not turned on. 15. The optical information reading device according to claim 1,
an optical information reading device main body including the housing, the camera, the illumination unit, a light-transmitting plate, a front diffusion plate, and the decoding means, and configured to be capable of switching between direct light, diffused light, and polarized light and irradiating the code;
An optical information reading device having a display capable of displaying lighting information indicating whether the lighting unit emitted direct light, diffuse light, or polarized light when the camera captured the code image in association with the code image. 16. The optical information reading device according to claim 15,
An optical information reader capable of setting which lighting group of the lighting units is to be used during operation. 14. The optical information reading device according to claim 9,
At least one of the diffusion plate, the polarizing plate, and the light-transmitting plate is detachably attached to the housing of the optical information reading device. 10. The optical information reading device according to claim 9,
An optical information reading device, wherein a light exit region of the polarizing plate is disposed between a light exit region of the light-transmitting plate and a light exit region of the light diffusing plate.