Code reader

Abstract

To obtain an image with brightness necessary for decoding, thereby enabling high-speed decoding.SOLUTION: A code reader 1 includes an illumination unit, an imaging unit having a Scheimpflug optical system, a control unit which executes decoding a code attached to a workpiece on the basis of an image output from the imaging unit, and an enclosure storing the illumination unit, the imaging unit and the control unit, and having a light-receiving window. The light-receiving window is provided on a first side face of the enclosure, and having a widthwise direction and a longitudinal direction. A plane formed by the light-receiving window intersects with a plane formed by a focal surface of the Scheimpflug optical system. The illumination unit is adjacent to the light-receiving window in the widthwise direction of the light-receiving window.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a code reader that reads a code attached to a workpiece transported by a transport device. [Background technology]

[0002] This type of code reader is used, for example, in a logistics site or the like when reading a code attached to a workpiece transported by a transport device. The code reader disclosed in Patent Document 1 is configured to be able to read the code attached to the bottom surface of the workpiece, and uses the gaps in the transport device to read the code. That is, when the transport device is composed of multiple conveyors, there are gaps between the conveyors arranged in the transport direction. By installing the code reader facing upward directly below the gap between the conveyors, when the workpiece being transported passes through the gap between the conveyors, the code reader irradiates illumination light toward the bottom surface of the workpiece and receives the reflected light from the bottom surface, thereby generating a code image. The workpieces are sorted based on the information obtained by decoding the code area of ​​the generated code image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Publication No. 2013 / 0292470 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, in logistics sites, it is desirable to increase the moving speed of the workpieces conveyed by the conveying device, but as the moving speed of the workpieces increases, the exposure time available for capturing an image of the code with a code reader becomes shorter, which makes it difficult to ensure the brightness of the image.

[0005] The present disclosure has been made in consideration of the above points, and an object of the present disclosure is to speed up the decoding process by making it possible to obtain an image with the brightness required for the decoding process. [Means for solving the problem]

[0006] In order to achieve the above object, the present embodiment can be based on a code reader that reads a code attached to a workpiece transported by a transport device. The code reader has a Scheimpflug optical system including an illumination unit that irradiates the workpiece with illumination light, a lens that collects reflected light from the code attached to the workpiece, and an image sensor having a light-receiving surface inclined with respect to the optical axis of the lens, an imaging unit that generates and outputs an image based on the amount of light received at the light-receiving surface, a control unit that executes a decoding process on the code attached to the workpiece based on the image output from the imaging unit, and a housing that houses the illumination unit, the imaging unit, and the control unit and has a light-receiving window that transmits the reflected light to its inside.

[0007] The light receiving window is provided on a first side surface of the housing and has a short side direction and a long side direction. A plane formed by the light receiving window intersects with a plane including a focal plane formed by the Scheimpflug optical system so as to extend from the near side to the far side of the imaging unit, and the illumination unit is disposed adjacent to the light receiving window in the short side direction when viewed from a direction facing the light receiving window.

[0008] According to this configuration, for example, when the housing is installed so that the range of the depth of field of the Scheimpflug optical system includes the gap of the transport device, the longitudinal direction of the light receiving window is aligned with the longitudinal direction of the gap of the transport device, so that the code attached to the workpiece can be imaged through the gap. At this time, since the illumination unit is adjacent to the short side of the light receiving window, the illumination optical axis and the optical axis of the lens of the imaging unit are close to each other, and the field of view of the imaging unit is brightly illuminated by the illumination unit. This allows an image with the brightness required for decoding to be obtained.

[0009] The illumination unit may include a near-distance illumination unit having an optical axis that intersects with the focal plane on the near side of the far side of the focal plane, and a far-distance illumination unit having an optical axis that intersects with the focal plane on the far side of the near side of the focal plane, in which case, the area where the illumination light of the near-distance illumination unit and the illumination light of the far-distance illumination unit overlap on the focal plane may be biased toward the far side rather than the near side, or the luminous flux of the far-distance illumination unit may be configured to be larger than the luminous flux of the near-distance illumination unit.

[0010] The angle of the optical axis of the near distance illumination unit with respect to the focal plane may be larger than the angle of the optical axis of the far distance illumination unit with respect to the focal plane, and the near distance illumination unit and the far distance illumination unit may be arranged adjacent to each other from the first side surface toward the inside of the housing, with the near distance illumination unit being arranged on the first side surface side.

[0011] The housing may further have a bottom surface adjacent to the first side surface, and an inclination angle of the far-field light-emitting substrate of the far-field illumination unit with respect to the bottom surface may be greater than an inclination angle of the near-field light-emitting substrate of the near-field illumination unit with respect to the bottom surface, and the far-field light-emitting substrate may be positioned higher than the near-field light-emitting substrate with respect to the bottom surface.

[0012] The housing may include a partition member disposed between the illumination unit and the image capture unit and optically separating the illumination unit from the image capture unit, thereby preventing stray light caused by the illumination light from entering the lens of the image capture unit, thereby producing a clearer image.

[0013] The code reader may further include a heat dissipation unit. In this case, the heat dissipation unit is provided adjacent to the illumination unit of the housing and can be thermally connected to the illumination unit, so that heat from the illumination unit can be efficiently dissipated to the outside.

[0014] The heat dissipation section may be disposed on a second side surface adjacent to the first side surface of the housing. The illumination section may have a light-emitting board on which one or more light-emitting elements are disposed, and the code reader may further include a support member that supports the light-emitting board, extends in a direction intersecting with the second side surface, and has thermal conductivity. The support member may be thermally connected to the light-emitting board and the heat dissipation section. That is, by providing the heat dissipation member on the second side surface of the housing, a large area that can be used for heat dissipation is secured, enhancing the heat dissipation effect, while irradiating illumination light from the first side surface.

[0015] The code reader may further include an internal reflection member that is stored in the housing and that reflects light incident on the imaging unit. In this case, the imaging unit may be disposed near one end of the housing in the longitudinal direction, and the illumination unit and the internal reflection member may be disposed near the other end of the housing in the longitudinal direction. This allows the imaging unit to be separated from the illumination unit that is prone to heat generation, while the optical axis of the lens of the imaging unit and the illumination optical axis to be brought closer together. Furthermore, by reflecting the light incident on the imaging unit, the optical path length can be increased, thereby widening the field of view.

[0016] The code reader may further include a connector portion that is connected to the outside. In this case, the illumination portion and the internal reflection member can be disposed between the light receiving window and the connector portion, so that a compact housing can be realized by disposing the illumination portion and the internal reflection member close to the light receiving window and providing the connector portion behind them.

[0017] The code reader may further include a communication unit that receives the dimensions of the gap (gap width) formed between the multiple transport mechanisms of the transport device and the transport speed of the transport device. In this case, the control unit can determine the frame rate of the imaging unit based on the dimensions of the gap and the transport speed. This makes it possible to determine a frame rate that allows synthesis from the transport conditions when generating a composite image based on multiple images output from the imaging unit. The gap and transport speed of the transport mechanisms may be directly input by a user or may be received as an instruction signal from another system.

[0018] The image sensor may have a plurality of imaging elements arranged in a row direction and a column direction, and the row direction may correspond to the direction from the near side to the far side of the focal plane of the Scheimpflug optical system. In this case, the aspect ratio of the image sensor is made smaller than the aspect ratio of the light receiving window, and the image sensor is configured to partially output signals from imaging elements in a row corresponding to the light receiving window among the plurality of imaging elements. That is, assuming that a line sensor is used as the image sensor, high-speed reading is possible, but the frame rate becomes extremely high to read the code, and there is a risk of increasing the amount of heat generated by the illumination unit. In this regard, by using an area sensor in which a plurality of imaging elements are arranged in a row direction and a column direction as the image sensor and partially reading only the portion corresponding to the light receiving window (some rows), it is possible to achieve both heat suppression and high-speed reading. Effect of the Invention

[0019] As described above, the illumination units are arranged adjacent to each other in the short direction of the light receiving window through which reflected light from the code attached to the work passes, so that the illumination optical axis and the optical axis of the lens of the imaging unit are brought closer together, allowing the illumination unit to brightly illuminate the field of view of the imaging unit. This makes it possible to obtain an image with the brightness required for decoding, even when imaging a workpiece moving at high speed, and thus speeding up the decoding process. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view illustrating a code reader according to an embodiment of the present invention during operation. [Diagram 2] FIG. 2 is a block diagram of the code reader. [Diagram 3] FIG. 3 is a diagram for explaining the code reader during operation, as viewed from the upstream side in the conveying direction. [Figure 4] FIG. 4 is a plan view illustrating the code reader during operation. [Diagram 5]FIG. 5 is a schematic diagram showing the relationship between the Scheimpflug optical system and the focal plane. [Figure 6A] FIG. 6A is a diagram showing an image of a code attached to the bottom surface of a workpiece captured from the side of the transport device and below the transport plane. [Figure 6B] FIG. 6B is a diagram showing the relationship between the field of view, the focal plane, and the in-focus range of the code reader according to this embodiment. [Figure 7] FIG. 7 is a front view of the code reader. [Figure 8] FIG. 8 is a side view of the code reader. [Figure 9] FIG. 9 is a rear view of the code reader. [Figure 10A] FIG. 10A is a perspective view of the code reader as viewed from the front side. [Figure 10B] FIG. 10B is a perspective view of the code reader as viewed from the rear side. [Figure 11] FIG. 11 is a diagram showing an example in which the code reader is installed directly below the transport device. [Figure 12] FIG. 12 is a diagram showing an example in which a code reader whose light receiving window is angled at less than 90 degrees with respect to the horizontal plane is installed directly below the transport device. [Figure 13] FIG. 13 is a diagram showing an example in which a code reader whose light receiving window is angled at less than 90 degrees with respect to the horizontal plane is installed on the side of a transport device. [Figure 14] FIG. 14 is a diagram showing an example in which a code reader whose light receiving window is at an angle of more than 90 degrees with respect to the horizontal plane is installed directly below a transport device. [Figure 15A] FIG. 15A is a cross-sectional view taken along line XV-XV in FIG. [Figure 15B] FIG. 15B is a diagram illustrating a first example of the near illumination section and the far illumination section in FIG. 15A. [Figure 15C] FIG. 15C is a diagram illustrating a second example of the near illumination section and the far illumination section in FIG. 15A. [Figure 16] FIG. 16 is a cross-sectional view taken along line XVI-XVI in FIG. [Figure 17]FIG. 17 is a diagram for explaining how the bottom surface of a workpiece is imaged during transportation. [Figure 18] FIG. 18 is a flowchart showing an example of a series of processes from imaging to outputting the read result. [Figure 19] FIG. 19 is a diagram for explaining a case where an image of the bottom surface of a workpiece being conveyed is captured from the side of the conveying device. [Figure 20] FIG. 20 is a diagram for explaining an example in which a plurality of code readers are installed. [Figure 21A] FIG. 21A is a diagram illustrating a first example in which the optical axes of a near illumination section and a far illumination section are provided substantially parallel to each other. [Figure 21B] FIG. 21B is a diagram illustrating a second example in which the optical axes of the near illumination section and the far illumination section are provided substantially parallel to each other. [Figure 22] FIG. 22 is a view corresponding to FIG. 4, showing a first example in which an external reflecting member is used. [Diagram 23] FIG. 23 is a view corresponding to FIG. 4, showing a second example in which an external reflecting member is used. [Figure 24] FIG. 24 is a side view showing a case where the workpiece is transported by a roller conveyor. [Diagram 25] FIG. 25 is a diagram showing the relationship between the field of view, the focal plane, and the in-focus range of a code reader in which the in-focus range is formed symmetrically with respect to the lens optical axis. [Figure 26] FIG. 26 is a schematic diagram showing the field of view and depth of a code reader according to a first example of another embodiment of the present invention. [Figure 27] FIG. 27 is a schematic diagram showing the field of view and depth of a code reader according to a second embodiment of the present invention. [Figure 28] FIG. 28 is a schematic diagram of a code reader according to a third embodiment of the present invention. [Figure 29] FIG. 29 is a schematic diagram of a code reader according to a fourth embodiment of the present invention. [Diagram 30] FIG. 30 is a perspective view of a code reader according to a fifth embodiment of the present invention, as viewed from the front side. [Diagram 31] FIG. 31 is a perspective view of a code reader according to a fifth embodiment of the present invention, as viewed diagonally from the front left side. [Diagram 32] FIG. 32 is a perspective view of a code reader according to a fifth embodiment of the present invention, as viewed from below. [Diagram 33] FIG. 33 is a perspective view of the fifth example from the lower right with the box-shaped case removed. [Diagram 34] FIG. 34 is an enlarged cross-sectional view of a mating portion between the box-shaped case and the lid-shaped case according to the fifth example. [Diagram 35] FIG. 35 is an enlarged cross-sectional view of a joint between a box-shaped case and a window frame according to the fifth example. [Diagram 36] FIG. 36 is a perspective view of the fifth example from above with the box-shaped case removed. [Figure 37] FIG. 37 is a bottom view of the code reader according to the fifth example. [Figure 38] FIG. 38 is a vertical cross-sectional view of a lid-shaped case according to the fifth example. [Figure 39] FIG. 39 is a cross-sectional view of a lid-shaped case according to the fifth example. [Diagram 40] FIG. 40 is a diagram showing an insertion portion for a fan cable according to the fifth example. [Diagram 41] FIG. 41 is a perspective view of a lens holder according to the fifth example. [Diagram 42] FIG. 42 is a view corresponding to FIG. 41, showing a state in which the sensor board according to the fifth example is removed. [Diagram 43] FIG. 43 is a view corresponding to FIG. 41, showing a state in which the sensor holder according to the fifth example is removed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, the 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 illustrative in nature and is not intended to limit the present invention, its applications, or its uses.

[0022] Fig. 1 is a schematic diagram showing a code reader 1 according to an embodiment of the present invention during operation. Fig. 2 is a block diagram of the code reader. This example shows a case where the code reader 1 is used at a logistics site where multiple workpieces W are handled. At the logistics site, a conveying device B is installed for sequentially conveying multiple workpieces W in a predetermined conveying direction. The conveying direction of the workpieces W is indicated by arrow A, and therefore the right side of Fig. 1 is the upstream side of the conveying direction, and the left side of Fig. 1 is the downstream side of the conveying direction.

[0023] The conveying device B has a plurality of conveying mechanisms B1 and B2. Each of the conveying mechanisms B1 and B2 is, for example, a belt conveyor, and includes an upstream conveying mechanism B1 and a downstream conveying mechanism B2. The upper surfaces of the upstream conveying mechanism B1 and the downstream conveying mechanism B2 are the conveying surfaces. In this embodiment, the conveying direction of the work W is defined as the Y direction, the direction perpendicular to the Y direction on the conveying surface is defined as the X direction, and the direction perpendicular to both the X direction and the Y direction is defined as the Z direction. In the logistics field, the X direction and the Y direction are often approximately horizontal, but the Y direction may be inclined with respect to the horizontal plane. The X direction may be called the width direction of the conveying mechanisms B1 and B2, or the longitudinal direction of the gap of the conveying device B. The Z direction may be called the height direction (up and down direction). Note that this definition of the direction is for convenience of explanation, and does not limit the direction during use.

[0024] The upstream transport mechanism B1 and the downstream transport mechanism B2 are provided with a gap in the transport direction. The size (dimension) of the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2 is not particularly limited, but is set so that the smallest workpiece W to be transported is smoothly transferred from the upstream transport mechanism B1 to the downstream transport mechanism B2 without falling through the gap. The longitudinal dimension (dimension in the X direction) of the gap is approximately the same as the width (dimension in the X direction) of the transport mechanisms B1 and B2, but this is also not particularly limited.

[0025] The upstream transport mechanism B1 and the downstream transport mechanism B2 are supported on a floor surface C (shown in FIG. 3) by members such as legs B3. Because of this, the transport surfaces of the upstream transport mechanism B1 and the downstream transport mechanism B2 are positioned at a predetermined distance above the floor surface C, a space may be formed below the upstream transport mechanism B1 and the downstream transport mechanism B2.

[0026] The code reader 1 is installed at an installation position set to the side of the conveying device B and below the conveying surface of the conveying device B. That is, as shown in Fig. 1, when the edge of the width direction of the conveying device B is projected vertically downward, the edge is located on an imaginary straight line L1. The imaginary straight line L1 is a straight line extending in the Y direction. The side of the conveying device B outboard of the imaginary straight line L1 in a top view can be defined as the side of the conveying device B. As also shown in Figs. 3 and 4, the installation position of the code reader 1 in this embodiment is set to the side of the conveying device B and directly beside the gap between the conveying mechanisms B1 and B2.

[0027] The dashed line indicated by the reference numeral 8 in FIG. 1 and FIG. 2 indicates the field of view of the imaging unit 3 (shown in FIG. 2) of the code reader 1, the details of which will be described later. The code reader 1 is installed at the installation position so that the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2 is included in the field of view of the imaging unit 3. Therefore, the code reader 1 of this embodiment is a stationary type. The operation of this stationary code reader 1 is when the operation of reading the codes of the works W transported by the transport device B is performed in sequence. The code reader 1 can be fixed to a vertical fixing surface of a frame F fixed to a floor surface C as shown in FIG. 3 via a mounting structure 71A described later, but it may also be fixed via a base or bracket (not shown), or it may be directly placed and fixed on the floor surface C, or it may be fixed to the transport mechanisms B1 and B2, or it may be fixed to the leg B3, and the installation target is not particularly limited.

[0028] Since the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2 is included in the field of view of the imaging unit 3, when the bottom surface of the workpiece W being transported passes through the gap, the bottom surface can be imaged by the imaging unit 3. A code may be attached to the bottom surface of the workpiece W. If a code is attached to the bottom surface of the workpiece W, the code reader 1 is installed at an installation position below the transport surface of the transport device B, so that the code attached to the bottom surface of the workpiece W can be read through the gap from below the transport surface of the transport device B.

[0029] The code attached to the work W 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 the present invention can be applied to any two-dimensional code. The code may be attached to the work W by directly printing or engraving it, or by printing it on a label and then attaching it to the work W, and the means and method are not important.

[0030] 1, the code reader 1 is connected to a computer 200 and a programmable logic controller (PLC) 201 by signal lines 200a and 201a, respectively, but this is not limiting, and the code reader 1, the computer 200, and the PLC 201 may each have a built-in wireless communication module, and the code reader 1 may be connected to the computer 200 and the PLC 201 by wireless communication. The PLC 201 is a control device for sequentially controlling the conveying device B and the code reader 1, and a general-purpose PLC may be used. The computer 200 may be a general-purpose or dedicated electronic computer, a portable terminal, or the like.

[0031] Moreover, during operation, the code reader 1 receives a read start trigger signal that specifies the start timing of code reading from the PLC 201 via the signal line 201a. Then, the code reader 1 captures an image of the code and decodes it based on the read start trigger signal. The decoded result is then transmitted to the PLC 201 via the signal line 201a. Thus, during operation of the code reader 1, the read start trigger signal is repeatedly input and the decoded result is repeatedly output via the signal line 201a between the code reader 1 and an external control device such as the PLC 201. Note that the read start trigger signal may be input and the decoded result may be output via the signal line 201a between the code reader 1 and the PLC 201 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 code reader 1, and the read start trigger signal may be input from the sensor to the code reader 1.

[0032] As shown in FIG. 2, the code reader 1 includes an illumination unit 2, an imaging unit 3, a control unit 4, a storage unit 5, and a communication unit 6. The control unit 4 includes an imaging control unit 41 that controls the imaging unit 3, an illumination control unit 42 that controls the illumination unit 2, a code detection unit 43, and a decoding unit 44. The storage unit 5 can be configured with a readable and writable storage device such as an SSD (Solid State Drive). The storage unit 5 can store, for example, various programs, decoded results, image data, setting information, and the like, and includes a decoded result storage unit 51, an image data storage unit 52, and a setting storage unit 53. Although not shown, the decoded result storage unit 51, the image data storage unit 52, and the setting storage unit 53 may be provided in separate storage devices.

[0033] The communication unit 6 is a part that executes communication with the computer 200 and the PLC 201. The setting information by the computer 200 is received by the control unit 4 via the communication unit 6. In addition, the control unit 4 receives a reading start trigger signal from the PLC 201 via the communication unit 6. The decoded result by the code reader 1 is transmitted to the computer 200 and the PLC 201 via the communication unit 6. In addition, the communication unit 6 receives the dimensions of the gaps formed between the multiple conveying mechanisms B1 and B2 of the conveying device B and the conveying speed of the conveying device B. The dimensions of the gaps and the conveying speed can be input in advance by the user to the computer 200 or the like. The input dimensions of the gaps and the conveying speed are stored in the computer 200, and the dimensions of the gaps and the conveying speed are received and acquired by the communication unit 6 after being transmitted from the computer 200.

[0034] The lighting unit 2 is a part that irradiates illumination light onto the workpiece W, and the illumination range of the lighting unit 2 includes the gap between the upstream conveying mechanism B1 and the downstream conveying mechanism B2. Since the code reader 1 is installed to the side of the conveying device B and below the conveying surface of the conveying device B, the lighting unit 2 irradiates illumination light from below the conveying surface toward the gap. As a result, when the bottom surface of the workpiece W being conveyed passes through the gap between the upstream conveying mechanism B1 and the downstream conveying mechanism B2, the bottom surface can be illuminated by the lighting unit 2. If a code is attached to the bottom surface of the workpiece W, the code attached to the bottom surface of the workpiece W can be illuminated by the lighting unit 2.

[0035] The illumination unit 2 has a near illumination unit 2a and a far illumination unit 2b. The near illumination unit 2a is a part that irradiates illumination light onto the near side of a focal plane 7 (shown in FIG. 6B) of a Scheimpflug optical system 31 described later. The far illumination unit 2b is a part that irradiates illumination light onto the far side of the focal plane 7 of the Scheimpflug optical system 31. The near illumination unit 2a and the far illumination unit 2b each include a light emitting body such as a light emitting diode (LED: Light Emission Diode) or the like.

[0036] The illumination unit 2 and the imaging unit 3 may be integrated, or the illumination unit 2 and the imaging unit 3 may be separate. The illumination unit 2 is controlled by an illumination control unit 42, which switches the illumination unit 2 on and off and changes the brightness when it is on. When a reading start trigger signal is input from the PLC 201, the illumination control unit 42 turns on the illumination unit 2 for a predetermined time and turns it off after the predetermined time has elapsed.

[0037] The imaging unit 3 is a part that captures an image of the workpiece W through the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2, generates a code image including a code, and outputs it to the control unit 4. The imaging unit 3 has a Scheimpflug optical system 31, a pre-processing circuit 32, and a plane mirror 33. As also shown in FIG. 5, the Scheimpflug optical system 31 has a lens 31a and an image sensor 31b having a light receiving surface inclined with respect to the optical axis 10 of the lens 31a. The lens 31a is an imaging lens that collects reflected light from the bottom surface of the workpiece W. The light incident on the lens 31a is emitted toward the light receiving surface of the image sensor 31b and forms an image on the light receiving surface.

[0038] The plane mirror 33 is a member for directing the light incident on the imaging unit 3 to the lens 31a. That is, in this example, since the Scheimpflug optical system 31 is included, the focal plane 7 is formed so as to extend in the V direction of the image sensor 31b. FIG. 6A shows a state in which the code attached to the bottom surface of the workpiece W is imaged from the side of the conveying device B and below the conveying surface. FIG. 6A also shows the shape of the focal plane 7 formed on the light receiving surface of the image sensor 31b, where the near side is relatively close to the code reader 1, and the far side is relatively far from the code reader 1. As shown in FIG. 6A, the gap between the workpiece W and the conveying device B appears larger on the near side than on the far side. That is, on the image sensor 31b, the bottom surface of the workpiece W seen through the gap between the conveying device B is captured in a trapezoid shape with one end on the near side, which is relatively close to the imaging unit 3, as the long side, and the other end on the far side, which is relatively far from the imaging unit 3, as the short side.

[0039] 6B, the field of view of the imaging unit 3 is indicated by reference numeral 8, and the in-focus range is indicated by reference numeral 9. Also, the optical axis (the optical axis of the lens 31a) extending through the center of the field of view 8 is indicated by reference numeral 10. In this manner, the Scheimpflug optical system 31 has the inclination of the focal plane 7 in the V direction of the image sensor 31b. Compared to the code reader shown in FIG. 25 in which the in-focus range 92 is formed symmetrically with respect to the lens optical axis 91, the code reader 1 of this embodiment makes it possible to fully include the longitudinal direction of the gap of the conveying device B within the in-focus range 9.

[0040] The image sensor 31b includes light receiving elements such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) that converts the image of the code obtained through the lens 31a into an electric signal. An image including the code is generated based on the amount of light received on the light receiving surface of the image sensor 31b. The image sensor 31b has a plurality of imaging elements arranged in row and column directions, and is configured so that the row direction is approximately the same as the direction from the near side to the far side of the focal plane of the Scheimpflug optical system 31. The aspect ratio of the image sensor 31b is set smaller than the aspect ratio of a light receiving window 67 described later. The image sensor 31b is configured to be able to partially output a signal from an imaging element corresponding to the light receiving window 67 among the plurality of imaging elements.

[0041] That is, assuming that a line sensor is used as the image sensor, high-speed readout is possible, but the frame rate for reading the code becomes extremely high, which may increase the amount of heat generated by the illumination unit 2. In this regard, in this embodiment, an area sensor in which multiple image pickup elements are arranged in row and column directions is used as the image sensor 31b, and only the portion corresponding to the light receiving window 67 (some of the rows) is partially read out, thereby making it possible to achieve both heat suppression and high-speed readout.

[0042] The image generated by the image sensor 31b is input to a pre-processing circuit 32. The pre-processing circuit 32 may be provided as necessary and is not essential.

[0043] The pre-processing circuit 32 is configured with an integrated circuit such as an FPGA (Field Programmable Gate Array), and is a part that performs various pre-processing on the image output from the image sensor 31b. The pre-processing includes, for example, various filter processes. The imaging unit 3 outputs the image that has been pre-processed by the pre-processing circuit 32 to the control unit 4. The pre-processing by the pre-processing circuit 32 may be performed as necessary, and an image that has not been pre-processed may be output to the control unit 4. The image output to the control unit 4 is stored in the image data storage unit 52 of the storage unit 5.

[0044] The imaging unit 3 is controlled by the imaging control unit 41. When a read start trigger signal is input from the PLC 201, the imaging control unit 41 generates an image by exposing for a preset exposure time. The imaging control unit 41 controls the imaging unit 3 to apply a preset gain to the image generated by the image sensor 31b, and also executes a process of amplifying the brightness of the image by digital image processing. The imaging control unit 41 also determines the frame rate (the number of images taken per second) of the imaging unit 3 based on the size (gap width) of the gap between the transport mechanisms B1 and B2 received by the communication unit 6 and the transport speed. For example, the imaging control unit 41 increases the frame rate of the imaging unit 3 as the transport speed increases. The frame rate can be set in the range of, for example, 500 fps to 5000 fps. The higher the frame rate, the stronger the light required to obtain sufficient brightness with a short exposure time, and the heat generation amount of the illumination unit 2 increases proportionally.

[0045] 7 to 10, the code reader 1 includes a housing 60 that houses the illumination unit 2, the imaging unit 3, and the control unit 4. The housing 60 may be configured to house the imaging unit 3 and the control unit 4, but not the illumination unit 2. In this case, the illumination unit 2 is configured as an illumination unit separate from the housing 60 that houses the imaging unit 3 and the control unit 4, but is controlled in synchronization with the control unit 4 when the workpiece W is imaged.

[0046] The housing 60 has a first side surface 61, a second side surface 62, a third side surface 63, and a fourth side surface 64, as well as a top surface 65 and a bottom surface 66. In this embodiment, the depth direction (front-rear direction), left-right direction, and top-bottom direction of the housing 60 are defined as shown in Figs. 7 to 10, but this definition is for convenience of explanation and does not limit the actual usage posture of the code reader 1. In addition, the number of sides is not limited to six, and a shape having six or more sides is also acceptable.

[0047] According to the above definition, the first side surface 61 is a surface (front surface) located on the front side of the housing 60, and has a shape long in the vertical direction. The second side surface 62 is adjacent to the left edge of the first side surface 61 and extends toward the back side of the housing 10, and is a surface (left side surface) located on the left side of the housing 60. The third side surface 63 is adjacent to the right edge of the first side surface 61 and extends toward the back side of the housing 10, and is a surface (right side surface) located on the right side of the housing 60. The fourth side surface 64 is a surface (rear surface) located on the rear side of the housing 60, and has a shape long in the vertical direction like the first side surface 61. The first side surface 61 and the fourth side surface 64 are approximately parallel to each other. In addition, the second side surface 62 and the third side surface 63 are approximately parallel to each other.

[0048] An upper edge of the fourth side surface 64 is located lower than an upper edge of the first side surface 61, and when the vertical dimension of the first side surface 61 is compared with the vertical dimension of the fourth side surface 64, the first side surface 61 is longer. The upper surface 65 is inclined so as to be positioned lower toward the back side of the housing 60 in order to correspond to the difference in vertical dimension between the first side surface 61 and the fourth side surface 64. On the other hand, the lower surface 66 extends approximately horizontally.

[0049] The first side surface 61, the third side surface 63, the fourth side surface 64, the top surface 65, and the bottom surface 66 of the housing 60 are integrally molded, and are configured, for example, as one part. Therefore, the first side surface 61, the third side surface 63, the fourth side surface 64, the top surface 65, and the bottom surface 66 configure a member whose left side is entirely open. A member configuring the second side surface 62 is fastened from the left side to the member configured by the first side surface 61, the third side surface 63, the fourth side surface 64, the top surface 65, and the bottom surface 66. In this way, a sealed housing 60 is configured.

[0050] As shown in FIG. 7, the first side surface 61 is provided with a light receiving window 67 that transmits reflected light from the bottom surface of the workpiece W into the inside of the housing 60. The light receiving window 67 is made of a transparent material having a short side direction and a long side direction. Examples of materials that constitute the light receiving window 67 include glass and resin materials such as polycarbonate. The long side direction of the light receiving window 67 coincides with the long side direction of the first side surface 61, i.e., the up-down direction of the housing 60, and the short side direction of the light receiving window 67 coincides with the left-right direction of the housing 60. In addition, the light receiving window 67 is provided offset to the right from the center of the first side surface 61 in the left-right direction.

[0051] The light receiving window 67 forms a plane extending along the up-down and left-right directions of the housing 60. The plane formed by the light receiving window 67 intersects with the plane formed by the focal plane 7 of the Scheimpflug optical system 31. The plane formed by the light receiving window 67 can also be defined as a virtual plane including the front surface (or back surface) of the light receiving window 67. Note that the light receiving window 67 does not have to be a perfect plane, and may be a gently curved surface that can be optically regarded as a plane.

[0052] 1 to 3, when the housing 60 is installed below the transport surface of the transport device B, the installation position and installation angle, etc. of the housing 60 are adjusted so that the focal range (depth of field) 9 of the Scheimpflug optical system 31 includes the gap of the transport device B and the focal plane 7 of the Scheimpflug optical system 31 is approximately parallel to the transport surface. When the housing 60 is installed in this manner, the light receiving window 67 is provided so that the plane formed by the light receiving window 67 intersects with the horizontal plane.

[0053] The installation position of the code reader 1 is not limited to the side of the transport device B. That is, for example, as shown in FIG. 11, if there is sufficient space available directly below the transport device B, the code reader 1 can be installed directly below the transport device B. For example, when the housing 60 is installed so that the optical axis of the lens 31a is approximately parallel to the transport direction A in a top view, the imaging unit 3 can be configured to be able to image the bottom surface of the workpiece W from the installation position through the mirror D as an external reflection member. In this case, the mirror D extending in an approximately vertical direction is installed on the side of the transport device B, and the reflected light from the bottom surface of the workpiece W is made to enter the mirror D, is folded back downward, and is made to enter the light receiving window 67. The code reader 1 according to the example shown in FIG. 11 is configured to include an external reflection member (mirror D) arranged outside the housing 60.

[0054] In this example, the angle at which the light receiving window 67 intersects with the horizontal plane is 90 degrees, but this is not limited to this, and when the code reader 1 is installed directly below the transport device B as shown in Fig. 12, the inclination angle α of the light receiving window 67 with respect to the horizontal plane E may be less than 90 degrees. The inclination angle α may be, for example, 20 degrees or more, or 45 degrees or more.

[0055] 13, a code reader 1 in which the angle of the light receiving window 67 is less than 90 degrees with respect to the horizontal plane E may be installed on the side of the transport device B. Also, as shown in Fig. 14, a code reader 1 in which the angle of the light receiving window 67 is more than 90 degrees with respect to the horizontal plane E may be installed directly below the transport device B. In this case, similar to the example shown in Fig. 11, the reflected light from the bottom surface of the workpiece W is made to enter the mirror D, is turned downward, and is made to enter the light receiving window 67.

[0056] Dust and debris are likely to fall onto the housing 60 installed below the transport surface of the transport device B, but since the light receiving window 67 is arranged to be inclined with respect to the horizontal plane E, dust and debris are less likely to accumulate on the light receiving window 67 compared to a light receiving window facing directly upward. In this embodiment, the light projection window 68 also faces in the same direction as the light receiving window 67, so dust and debris are also less likely to accumulate on the light projection window 68. In particular, as shown in Figure 14, since the angle of the light receiving window 67 with respect to the horizontal plane E exceeds 90 degrees, dust and debris hardly adheres to the light receiving window 67.

[0057] In the case of FIG. 12, the angle of the light receiving window 67 with respect to the horizontal plane E is less than 90 degrees. However, if this angle were set to 45 degrees or more, foreign matter on the surface of the light receiving window would be more likely to slide off.

[0058] That is, μ≦tan(θ) If θ≧arctan(μ), then foreign matter on the surface of the light-receiving window 67 will be more likely to slide off. For example, assuming that the coefficient of friction μ between glass, polycarbonate, etc. and other materials is normally 1 or less, in order to prevent foreign matter from accumulating, if the light-receiving window 67 is made of glass, polycarbonate, etc., then it is preferable for the angle it makes with the horizontal plane E to be 45 degrees or more.

[0059] 1 to 3 and 11 to 14, when the housing 60 is installed, the distance between the light receiving window 67 and the gap of the transport device B, the orientation of the light receiving window 67 with respect to the gap, etc. are determined. When the housing 60 is installed in this manner with the light receiving window 67 aligned so as to face the longitudinal direction of the gap of the transport device B, the imaging unit 3 is configured so that the range (depth of field) in which the Scheimpflug optical system 31 is in focus includes the gap of the transport device B. At this time, the gap is included in the middle part of the depth of field of the Scheimpflug optical system 31.

[0060] As shown in FIG. 7, the first side surface 61 is provided with a light projection window 68 that transmits the illumination light emitted from the illumination unit 2 to the outside of the housing 60. In this embodiment, the light receiving window 67 and the light projection window 68 are made of a common transparent material, and the area to the right of the dashed dotted line L2 in FIG. 7 is the light receiving window 67, and the area to the left of the dashed dotted line L2 is the light projection window 68. In this manner, the light receiving window 67 and the light projection window 68 are provided adjacent to each other in the left-right direction. Like the light receiving window 67, the light projection window 68 also has a short side direction and a long side direction, and the long side direction coincides with the long side direction of the first side surface 61. The light receiving window 67 and the light projection window 68 may be made of separate materials.

[0061] As shown in FIG. 10B, the code reader 1 includes a heat dissipation fin (heat dissipation section) 69 for dissipating heat generated in the illumination section 2 to the outside of the housing 60. The heat dissipation fin 69 is disposed on the second side surface 62 of the housing 60. Specifically, the second side surface 62 located on the left side of the housing 60 is made of a material having high thermal conductivity, such as an aluminum alloy, and the heat dissipation fin 69 is integrally formed with the member constituting the second side surface 62. Therefore, the heat dissipation fin 69 is also made of a material having high thermal conductivity. The heat dissipation fin 69 may be a separate body from the second side surface 62.

[0062] The heat dissipation fin 69 protrudes leftward from the second side surface 62 and extends in the vertical direction. A plurality of heat dissipation fins 69 having this shape are provided at intervals in the depth direction. The heat dissipation fins 69 are adjacent to the illumination unit 2 of the housing 60 in the left-right direction, which improves the heat dissipation efficiency of the illumination unit 2.

[0063] A cooling fan 70 is provided in the vertical middle of the heat dissipation fins 69. The fan 70 is controlled by, for example, the control unit 4, and is configured to operate when the temperature of the housing 60 reaches or exceeds a predetermined temperature. The fan 70 sends outside air to the heat dissipation fins 69, making it possible to perform forced air cooling. The fan 70 and heat dissipation fins 69 may be provided as needed.

[0064] As shown in FIG. 10B, the housing 60 has a second side surface 62 as an attachment surface on which the attachment structure 71A is provided, which is different from the first side surface 61 on which the light receiving window 67 is provided. As shown in FIG. 6B, when the code reader 1 (housing 60) is located to the side of the conveying device B and below the conveying surface and is fixed to a vertical fixing surface of a frame F arranged on a floor surface C via the mounting surface, the Scheimpflug optical system of the imaging unit 3 forms a range in focus extending in the longitudinal direction of the gap of the conveying device B. By fixing the mounting surface of the housing to a general horizontal or vertical surface as an external fixing surface, the housing 60 can be positioned so that a range in focus is formed in the longitudinal direction of the gap of the conveying device B. The focal surface may be parallel to the conveying surface.

[0065] The mounting structure 71A may be, for example, a plurality of screw holes, and the housing 60 may be fixed to the frame F using a screw for each screw hole. However, the mounting structure 71A may be a plurality of bolts, and the housing 60 may be fixed to the frame F using a nut for each bolt, or may be a structure that can be fixed with a clamp metal fitting. The mounting structure 71A may be provided on the heat dissipation fin 69 or the fan 70 arranged on the second side surface 62. The mounting surface is not limited to the second side surface 62, and the mounting structure 71A may be provided on a surface other than the first side surface on which the light receiving window 67 and the light projecting window 68 are provided, that is, at least one of the second side surface, the third side surface 63, the fourth side surface 64, the upper surface 65, and the lower surface 66, so as not to interfere with the irradiation of the illumination light by the illumination unit 2 and the reception of the light by the imaging unit 3. For example, if the upper surface 65 or the lower surface 66 is used as the mounting surface, the mounting structure 71A may be placed and fixed on a plate or the like provided protruding from the frame F as an external horizontal fixing surface via the mounting surface. The mounting surface may be directly attached to the fixed surface, or may be indirectly attached to the fixed surface using an intermediate part such as a bracket. That is, even if the mounting surface is the second side surface 62, it may be attached to a horizontal fixed surface via the mounting structure 71A and an intermediate part.

[0066] A surface that is approximately parallel to the focal plane 7 of the Scheimpflug optical system may be provided on at least a part of the upper surface 65. Since the conveying surface of the conveying device B is generally horizontal, by placing a level on the upper surface 65, the installation state of the housing 60 in which the focal plane 7 is parallel to the conveying surface can be achieved with higher accuracy.

[0067] 7, when the housing 60 is viewed from the front, that is, when viewed from a direction directly facing the light-receiving window 67, the illumination unit 2 is disposed adjacent to the light-receiving window 67 in the short side direction (left-right direction) of the light-receiving window 67. The fact that the illumination unit 2 is adjacent to the light-receiving window 67 in the short side direction means that the optical axis (illumination optical axis) of the illumination unit 2 and the optical axis of the lens 31a of the imaging unit 3 are close to each other, and the field of view of the imaging unit 3 is brightly illuminated by the illumination unit 2.

[0068] In the illumination unit 2, the positions where the optical axes of the illumination units 2a and 2b intersect with the focal plane 7 are different in the direction in which the focal plane extends so as to suppress the deficiency of illuminance on the far side of the imaging unit 3 relative to the near side of the imaging unit 3 on the focal plane 7 of the Scheimpflug optical system 31, or to make the illuminance on the far side equal to or greater than the illuminance on the near side. This makes it possible to suppress the deficiency of the amount of reflected light received from the far side relative to the amount of reflected light received from the near side of the imaging unit 3, and an image with more uniform luminance is generated on the near side and far side of the imaging unit 3, so that both codes close to the imaging unit and codes far from the imaging unit can be read in a short time. Note that an image with more uniform luminance on the near side and far side of the imaging unit 3 is, for example, an image in which the average luminance value of a dark code on the far side is 50% or more of the average luminance value of a bright code on the near side, and more preferably, an image in which the average luminance value of a dark code on the far side is 60% or more of the average luminance value of a bright code on the near side.

[0069] In order to provide different amounts of light for the far and near sides, the illumination unit 2 has a near illumination unit 2a and a far illumination unit 2b. The far illumination unit 2b differs from the near illumination unit 2a in at least one of the optical axis angle with respect to the focal plane 7 of the Scheimpflug optical system 31 or the light flux.

[0070] 15A, 15B, and 15C, the near-use illumination unit 2a having an optical axis L3 that intersects with the focal plane 7 on the near side of the focal plane 7 relative to the far side of the focal plane 7 and the far-use illumination unit 2b having an optical axis L4 that intersects with the focal plane 7 on the far side of the focal plane 7 in the illumination unit 2 according to this embodiment have different optical axis angles with respect to the focal plane 7 of the Scheimpflug optical system 31, and the optical axis L3 and the optical axis L4 intersect in a region before reaching the focal plane 7. In other words, the angle of the optical axis L3 of the near-use illumination unit 2a with respect to the focal plane 7 is configured to be larger than the angle of the optical axis L4 of the far-use illumination unit 2b with respect to the focal plane 7.

[0071] In the first example shown in FIG. 15B, the area where the illumination light of the near illumination unit 2a and the illumination light of the far illumination unit 2b overlap on the focal plane 7 is biased toward the far side. The second example shown in FIG. 15C is different from the first example in FIG. 15B in that the overlapping area is reduced by narrowing the light distribution angle of each illumination unit, while the luminous flux of the far illumination unit 2b is made larger than the luminous flux of the near illumination unit 2a. In both cases of FIG. 15B and FIG. 15C, the illuminance shortage on the far side relative to the near side of the focal plane 7 can be suppressed, or the illuminance on the far side can be made equal to or greater than the illuminance on the near side. As a result, by suppressing the luminance shortage on the far side relative to the luminance on the near side of the image output by the imaging unit 3, an image with more uniform luminance on the near side and the far side of the imaging unit 3 can be generated, thereby improving the reading efficiency.

[0072] 15A, the near field illumination unit 2a and the far field illumination unit 2b are arranged adjacent to each other on a first side surface 61 of the housing 60, i.e., from the light projection window 68 toward the inside of the housing 60. The near field illumination unit 2a is arranged on the first side surface 61 side, and the far field illumination unit 2b is arranged on the rear side of the near field illumination unit 2a.

[0073] The near-field illumination unit 2a has a near-field light-emitting board 2c, one or more near-field light-emitting elements 2d, and a near-field illumination lens 2e. The near-field light-emitting board 2c is disposed toward the lower end in the housing 60, and is inclined with respect to the horizontal plane so as to be positioned higher toward the back side of the housing 60. The code reader 1 includes a near-side support member 71 that supports the near-field light-emitting board 2c on the second side surface 62. The near-side support member 71 is fixed to the second side surface 62, and is formed so as to protrude from the second side surface 62 toward the inside of the housing 60, and extends in a direction intersecting with the second side surface 62. A surface facing downward of the near-field light-emitting board 2c is fixed to a portion of the near-side support member 71 that protrudes toward the inside of the housing 60.

[0074] The near-use illumination unit 2a and the heat dissipation fin 69 are thermally connected via the near-side support member 71. That is, the near-side support member 71 is made of, for example, an aluminum alloy or a resin material as a material having thermal conductivity. Grease or the like for improving thermal conductivity is interposed between the near-side support member 71 and the second side surface 62 and between the near-side support member 71 and the near-use light-emitting board 2c. This makes it easier for heat emitted by the near-use light-emitting element 2d to be transferred to the heat dissipation fin 69 via the near-use light-emitting board 2c and the near-side support member 71. "Thermal connection" means that the connection is made in a state where heat can easily move and without any heat insulating material interposed.

[0075] A plurality of near-use light-emitting elements 2d are arranged (mounted) on the upward surface of the near-use light-emitting substrate 2c in a state of being lined up in the depth direction of the housing 60. The near-use illumination lens 2e is provided so as to cover the light-emitting surface of each near-use light-emitting element 2d. The optical axis of the near-use illumination unit 2a is indicated by a dashed dotted line L3. The optical axis L3 of the near-use illumination unit 2a is directed toward the near side of the focal plane 7 of the Scheimpflug optical system 31, and the orientation of the near-use light-emitting substrate 2c, i.e., the orientation of the near-use light-emitting element 2d, is set and the near-use illumination lens 2e is designed so that such an optical axis L3 is formed.

[0076] The long-distance illumination section 2b has a long-distance light-emitting board 2f, one or more long-distance light-emitting elements 2g, and a long-distance illumination lens 2h. The long-distance light-emitting board 2f is disposed adjacent to the rear end of the near-distance light-emitting board 2c, and is inclined with respect to the horizontal plane so that the far-distance light-emitting board 2f is positioned higher toward the rear of the housing 60. The inclination angle of the long-distance light-emitting board 2f with respect to the horizontal plane is larger than the inclination angle of the near-distance light-emitting board 2c with respect to the horizontal plane, and therefore the long-distance light-emitting board 2f has a steeper inclination than the near-distance light-emitting board 2c.

[0077] The code reader 1 includes a far-side support member 72 that supports the far-field light emitting board 2f on the second side surface 62. The far-side support member 72 is fixed to the second side surface 62 and is formed so as to protrude from the second side surface 62 toward the inside of the housing 60. A downward surface of the far-field light emitting board 2f is fixed to a portion of the far-side support member 72 that protrudes toward the inside of the housing 60. The far-field illumination section 2b and the heat dissipation fin 69 are thermally connected via the far-side support member 72, similar to the far-field illumination section 2b.

[0078] On the upward surface of the far-field light emitting substrate 2f, a plurality of far-field light emitting elements 2g are arranged (mounted) in a line in the depth direction of the housing 60. The number of far-field light emitting elements 2g is set to be greater than the number of near-field light emitting elements 2d. This makes the amount of light emitted by the far-field illumination section 2b greater than the amount of light emitted by the near-field illumination section 2a.

[0079] The long-distance illumination lens 2h is provided so as to cover the light-emitting surface of each long-distance light-emitting element 2g. The optical axis of the long-distance illumination unit 2b is indicated by a dashed line L4. The optical axis L4 of the long-distance illumination unit 2b is directed toward the long-distance side of the focal plane 7 of the Scheimpflug optical system 31, and the orientation of the long-distance light-emitting substrate 2f, i.e., the orientation of the long-distance light-emitting element 2g, is set and the long-distance illumination lens 2h is designed so that such an optical axis L4 is formed.

[0080] The inclination angle of the far-field light-emitting board 2f of the far-field illumination section 2b with respect to the lower surface 66 adjacent to the first side surface 61 is larger than the inclination angle of the near-field light-emitting board 2c of the near-field illumination section 2a with respect to the lower surface 66, and the far-field light-emitting board 2f is disposed higher than the near-field light-emitting board 2c with respect to the lower surface 66. As a result, the range in which illumination light from the illumination section 2 (particularly the near-field illumination section 2a) can be irradiated can be brought closer to the first side surface 61 of the housing 60, so that the housing 60 can be installed at a position closer to the transport device B, and the height of the housing 60 can also be reduced, so that a code reader 1 that is easy to install even in a logistics site or the like where installation space is likely to be restricted can be realized.

[0081] As an example of the configuration of the housing 60, in this embodiment, the second side surface 62 is made of a metal plate, and members such as the near side support member 71, the far side support member 72, the sensor mounting bracket 80, the upper mounting bracket 81, the lower mounting bracket 84, and the control board 90 are arranged and fixed on the metal plate, and each member is covered with a cover member having a surface other than the second side surface 62 (i.e., the first side surface 61, the third side surface 63, the fourth side surface 64, the upper surface 65, and the lower surface 66), and the inside of the housing 60 is sealed together with the metal plate. The cover member is made of a metal material or a resin material. If the cover member is made of a metal material, the housing 60 can be made more robust, and if the cover member is made of a resin material, the housing 60 can be made lighter. The heat dissipation fins 69 are arranged to extend from the surface opposite to the surface on which each member of the metal plate (second side surface 62) is arranged.

[0082] 16, the housing 60 includes a partition member 75 that is disposed between the illumination unit 2 and the imaging unit 3 and optically separates the illumination unit 2 from the imaging unit 3. The partition member 75 is made of a resin material, a metal material, or the like having light blocking properties, and includes a side plate portion 75a (also shown in FIG. 15) formed so as to protrude from the second side surface 62 toward the inside of the housing 60, and a vertical plate portion 75b connected to the end of the side plate portion 75a on the inside of the housing 60. As a result, the illumination light irradiated from the illumination unit 2 is emitted to the outside of the housing 60 only from the light projection window 68, making it difficult for stray light to enter the imaging unit 3.

[0083] The imaging unit 3 is disposed toward the upper end within the housing 60. When the light receiving window 67 is used as a reference, the upper end within the housing 60 corresponds to one end in the longitudinal direction of the light receiving window 67. Therefore, the imaging unit 3 is disposed toward one end in the longitudinal direction of the light receiving window 67 within the housing 60. On the other hand, the lower end within the housing 60 corresponds to the other end in the longitudinal direction of the light receiving window 67 when the light receiving window 67 is used as a reference. Therefore, the illumination unit 2 is disposed toward the other end in the longitudinal direction of the light receiving window 67 within the housing 60.

[0084] The image sensor 31b of the imaging unit 3 is disposed at the rear side within the housing 60 and is fixed to the second side surface 62 by a sensor mounting bracket 80. The light receiving surface of the image sensor 31b faces the front side. The lens 31a of the imaging unit 3 is disposed at the front side of the image sensor 31b within the housing 60 and is fixed to the second side surface 62. The optical axis of the lens 31a extends in the depth direction of the housing 60. The plane mirror 33 of the imaging unit 3 is disposed at the front side of the lens 31a within the housing 60 and is fixed to the second side surface 62 by an upper mounting bracket 81. The reflective surface of the plane mirror 33 faces diagonally downward.

[0085] The code reader 1 is housed in the housing 60 and includes an internal reflection member 83 that folds back light incident on the imaging unit 3. The internal reflection member 83 is disposed near the lower end of the housing 60 and is fixed to the second side surface 62 by a lower mounting bracket 84. The front end of the internal reflection member 83 is positioned near the lower end of the light receiving window 67. On the other hand, the rear end of the internal reflection member 83 is positioned closer to the front than the rear end of the housing 60. The reflection surface of the internal reflection member 83 faces upward, and is inclined so that the reflection surface is located higher toward the rear. The internal reflection member 83 is disposed below and the imaging unit 3 is disposed above, and light incident from above through the light receiving window 67 is folded back by the internal reflection member 83 to be incident on the image sensor 31b. This allows the height dimension of the housing 60 to be shortened and the code reader 1 to be made compact.

[0086] As shown in Figs. 8 to 10 etc., the code reader 1 includes a marker 59. The marker 59 is provided on the top surface 65 of the housing 60, and is controlled by the control unit 4 to be switched between a lit state and an unlit state. The marker 59 is a member for indicating success or failure of code reading to a user by color, and glows, for example, green when successful and red when unsuccessful or abnormal. The control unit 4 controls the marker 59 to be turned off when an image is captured by the imaging unit 3.

[0087] The code reader 1 includes a connector unit 85 that is connected to the outside. The computer 200, the PLC 201, a power source, and the like are connected to the connector unit 85. The connector unit 85 is provided on the rear side of the housing 60 so as to face the outside of the housing 60. Specifically, a recess 64a is provided on the fourth side surface 64 of the housing 60, and the connector unit 85 is attached to the inner side surface 64b of the recess 64a. In this embodiment, an example is shown in which a plurality of connector units 85 are provided at intervals from each other in the vertical direction, but the number of connector units 85 can be set arbitrarily. The connector unit 85 has an insertion port 85a into which a terminal (not shown) of a wiring line or the like is inserted. Since the insertion port 85a opens toward the right, the terminal of the wiring line can be inserted into each insertion port 85a from the right side of the housing 60.

[0088] The image sensor 31b is disposed directly above the connector section 85. The illumination section 2 and the internal reflection member 83 are disposed between the light receiving window 67 and the connector section 85. That is, since the lens 31a, the image sensor 31b, and the plane mirror 33 constituting the imaging section 3 need to be disposed at intervals in the depth direction of the housing 60, it is difficult to secure a space for disposing the connector section 85 at the top of the housing 60. However, since the illumination section 2 and the internal reflection member 83 can be shorter in the depth direction of the housing 60 than the imaging section 3, in this embodiment, it is possible to secure a space for disposing the connector section 85 on the back side of the illumination section 2 and the internal reflection member 83 without increasing the size of the housing 60.

[0089] When the code reader 1 is installed as shown in Figs. 1 to 3, the bottom surface of the workpiece W transported by the transport device B is exposed downward from the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2. The depth of field of the imaging unit 3 of the code reader 1 installed as shown in Figs. 1 to 3 includes the bottom surface of the workpiece W exposed from the gap in the transport device B. This allows the imaging unit 3 to directly image the bottom surface of the workpiece W through the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2. "Directly" means that the imaging unit 3 images the bottom surface of the workpiece W without going through a reflective member such as a mirror.

[0090] When installed as shown in Figures 1 to 3, the light receiving window 67 is aligned with the gap of the conveying device B, and in this state, the row direction of the image sensor 31b corresponds to the extension direction of the gap of the conveying device B, and the column direction of the image sensor 31b corresponds to the conveying direction of the conveying device B (the direction indicated by arrow A in Figure 1).

[0091] Therefore, as shown in FIG. 17, the imaging unit 3 continuously captures the bottom surface of the workpiece W that is exposed through the gap of the conveying device B and is included in the depth of field of the imaging unit 3, thereby outputting a plurality of images in which a part of the code attached to the bottom surface of the workpiece W is captured. The upper side of FIG. 17 shows the upstream conveying mechanism B1 and the downstream conveying mechanism B2 conveying the workpiece W as viewed from below, and the workpiece W is conveyed as shown from left to right. Since the dimension of the code in the conveying direction is longer than the gap between the upstream conveying mechanism B1 and the downstream conveying mechanism B2, only a part of the code in the conveying direction is exposed downward from the gap between the upstream conveying mechanism B1 and the downstream conveying mechanism B2. As shown in the lower side of FIG. 17, a plurality of images in which a part of the code in the conveying direction is captured are sequentially output from the imaging unit 3. The plurality of images output from the imaging unit 3 are input to the control unit 4. The image output from the imaging unit 3 becomes an image that is elongated in the longitudinal direction of the gap between the upstream conveying mechanism B1 and the downstream conveying mechanism B2 by geometric correction described later.

[0092] (Details of control unit 4) The control unit 4 is a part that generates a composite image based on the multiple images output from the imaging unit 3, and executes a decoding process on the code attached to the bottom surface of the workpiece W based on the composite image. As shown in Fig. 2, a specific configuration example of the control unit 4 can be, for example, a configuration example including a microcomputer having a central processing unit, ROM, RAM, etc. An imaging control unit 41, an illumination control unit 42, a code detection unit 43, and a decoding unit 44 are configured by hardware included in the control unit 4, software executed by the control unit 4, etc.

[0093] The code detection unit 43 of the control unit 4 is a unit that identifies a code area based on the code image output from the imaging unit 3 and detects a code from the identified code area. The decode unit 44 of the control unit 4 is a unit that decodes the code detected by the code detection unit 43. Specifically, since the code is represented by black and white binary data, the decode unit 44 decodes the black and white binary data. A table showing the correspondence between encoded data can be used for the decoding. Furthermore, the decode unit 44 checks whether the decoded result is correct or not according to a predetermined check method. If an error is found in the data, the decode unit 44 uses an error correction function to calculate the correct data. The error correction function differs depending on the type of code. The details of the code detection unit 43 and the decode unit 44 will be specifically described below.

[0094] The details of the process by the control unit 4 will be described below based on the flowchart shown in Fig. 18. This flowchart starts when the operation of the code reader 1 is started. After the start, in step SA1, a read start trigger signal is input from the PLC 201 to the code reader 1. When the read start trigger signal is input, the illumination control unit 42 turns on the illumination unit 2, and the imaging control unit 41 causes the imaging unit 3 to capture an image and generate an image.

[0095] The area surrounded by the two-dot chain line in FIG. 19 is the image output from the imaging unit 3. In this embodiment, since the code reader 1 is installed to the side of the transport device B, the bottom surface of the workpiece W is imaged from diagonally below. Therefore, unlike the case where the image is taken from directly below, a geometric change occurs according to the installation angle of the code reader 1 as shown in FIG. 19. Specifically, in the multiple images output from the imaging unit 3, the bottom surface of the workpiece W exposed from the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2 appears as a trapezoid with one end on the near side of the focal plane of the Scheimpflug optical system 31 as the long side and the other end on the far side of the focal plane of the Scheimpflug optical system 31 as the short side.

[0096] For this reason, in step SA2 of the flowchart shown in Fig. 18, the code detection unit 43 performs keystone correction on the trapezoidal shapes of the multiple images as geometric correction. Specifically, the code detection unit 43 acquires information related to the installation angle of the code reader 1. The information related to the installation angle of the code reader 1 may be information input by the user when setting up the code reader 1, or may be information automatically detected by the code reader 1. The code detection unit 43 performs geometric correction on each of the multiple images output from the imaging unit 3 based on the information related to the installation angle of the code reader 1. As a result, an image similar to that when imaged from directly below the workpiece W is obtained.

[0097] In step SA3, the code detection unit 43 synthesizes the multiple processed images that have been geometrically corrected in step SA2 to generate a composite image including the code. In step SA4, it is determined whether the number of times imaging by the imaging unit 3 has reached a designated number. This number is set to a number that allows the entire code to be imaged. If the determination in step SA4 is NO, the process proceeds to step SA1, where imaging, geometric correction, and image synthesis are repeated until the entire code is imaged. If the determination in step SA4 is YES, the process proceeds to step SA5.

[0098] In step SA5, the code detection unit 43 applies multiple edge extraction filters to the image synthesized in step SA3 to extract edges of different frequencies to generate multiple edge images, and then performs integration processing of the multiple edge images. The code detection unit 43 determines the code candidate position based on the result of the edge integration processing. That is, in the edge-processed image, it is possible to estimate that an area where many pixels with high brightness values ​​are concentrated is a code area.

[0099] For example, the code detection unit 43 can generate a heat map image that indicates the likelihood of a code in order to search for the position of a code in a code image. That is, the code detection unit 43 quantifies the feature amount of the code, generates a heat map in which the magnitude of the feature amount is assigned to each pixel value, and extracts a code candidate area on the heat map in which a code is likely to exist. As a specific example, there is a method of acquiring the feature portion of the code in an area that is relatively hot (has a large feature amount) in the heat map. When multiple feature portions are acquired, they can be extracted by prioritizing them and stored in a RAM or the like. By using the heat map image, it becomes possible to detect the code area at high speed. The decoding unit 44 decodes the code searched for by the code detection unit 43.

[0100] (Effects of the embodiment) The code reader 1 according to the present embodiment can be fixed to a horizontal or vertical surface, which is a common external fixed surface located to the side of the transport device B and below the transport surface, via the mounting surface of the housing, so that the housing can be oriented so that a range in focus is formed in the longitudinal direction of the gap of the transport device B. The height position can be adjusted by moving the housing while maintaining the orientation, for example, using an image to be actually captured or the height from the top surface of the housing to the focal plane obtained based on the Scheimpflug optical system and the housing design, making installation easy. In addition, since the plane formed by the light receiving window 67 in the above installation state intersects with the horizontal plane, dust and dirt are less likely to accumulate on the light receiving window 67. In addition, since the code reader 1 is installed to the side of the transport device B, the light receiving window 67 is disposed at a position outside the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2. As a result, dust and dirt that have fallen from the gap between the upstream transport mechanism B1 and the downstream transport mechanism B2 are less likely to adhere to the light receiving window 67. The same applies to the light projection window 68. This reduces the frequency of maintenance such as cleaning, thereby easing the burden on the user.

[0101] Furthermore, when the housing 60 is installed so that the depth of field of the Scheimpflug optical system 31 includes the gap of the transport device B, the longitudinal direction of the light receiving window 67 can be made to correspond to the longitudinal direction of the gap of the transport device B. This makes it possible to capture an image of the code attached to the workpiece W through the gap of the transport device B. At this time, since the illumination unit 2 is adjacent to the light receiving window 67 in the short direction, the illumination optical axis and the optical axis of the lens 31a of the imaging unit 3 are close to each other, and the field of view of the imaging unit 3 is brightly illuminated by the illumination unit 2. This allows an image with the brightness required for decoding processing to be obtained.

[0102] (Other embodiments) The above-described embodiment is merely illustrative 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.

[0103] Fig. 20 is a diagram showing a case where a code reader 1 is installed on each side of a conveying device B. As shown in this figure, by installing multiple code readers 1 so as to image the workpiece W from opposite directions, it is possible to accommodate a conveying device B having a wide width in the X direction and to reduce blind spots. The shape of the workpiece W is not particularly limited, and may be a cylindrical workpiece W as shown in Fig. 20. The code reader 1 of the present disclosure images the workpiece W from diagonally below, so that it is possible to expand the range in which the code affixed to the part of the workpiece W that is not in contact with the conveying surface can be read, even for a cylindrical workpiece W.

[0104] In the above-described embodiment, as shown in Fig. 15B and Fig. 15C, the inclination angles of the optical axes of the near use illumination unit 2a and the far use illumination unit 2b with respect to the focal plane 7 are different in side view. This allows the near use illumination unit 2a and the far use illumination unit 2b to be made compact and the height dimension of the housing 60 to be shortened, but this is not limited thereto. For example, as shown typically in Fig. 21A and Fig. 21B, the optical axes of the near use illumination unit 2a and the far use illumination unit 2b may be arranged to be substantially parallel, that is, the inclination angles of the optical axes with respect to the focal plane 7 may be substantially the same.

[0105] In the case of FIG. 21A, the area where the illumination light from the near-use illumination unit 2a and the illumination light from the far-use illumination unit 2b overlap on the focal plane 7 is biased toward the far side of the focal plane 7 rather than the near side. In the case of FIG. 21B, the light distribution angle of the illumination light from the near-use illumination unit 2a and the illumination light from the far-use illumination unit 2b is narrowed to reduce the area where they overlap on the focal plane 7, while the luminous flux of the far-use illumination unit 2b is made larger than the luminous flux of the near-use illumination unit 2a, as compared with FIG. 21A. In either case, by suppressing the illuminance shortage on the far side relative to the near side of the focal plane 7, or by making the illuminance on the far side equal to or greater than the illuminance on the near side, the luminance shortage on the far side relative to the luminance on the near side of the image output by the imaging unit 3 can be suppressed, and therefore an image with more uniform luminance on the near side and far side of the imaging unit 3 can be generated, thereby improving the reading efficiency.

[0106] 22, when the code reader 1 is installed on the side of the transport device B, a mirror (external reflection member) D1 may be used to reflect light. The mirror D1 may be attached to the housing 60, or may be attached to a member separate from the housing 60. This is an effective installation method when it is not possible to ensure sufficient installation space on the side of the transport device B to align the light receiving window 67 so that it faces the longitudinal direction of the gap in the transport device B.

[0107] 23, when the code reader 1 is installed directly below the transport device B, a mirror (external reflection member) D2 may be used to reflect light. The mirror D2 may be attached to the housing 60, or may be attached to a member separate from the housing 60. When almost no installation space can be secured to the side of the transport device B, the code reader 1 can be installed directly below the transport device B.

[0108] In both cases of Figures 22 and 23, when the housing 60 is installed so that the optical axis 10 of the lens inside the housing 60 is approximately parallel to the conveying direction (Y direction) when viewed from above, the optical axis 10 of the lens outside the housing 60 is folded back by a mirror (external reflective member) D2 to a direction (X direction) approximately parallel to the longitudinal direction of the gap of the conveying device B when viewed from above, so that the imaging unit 3 is configured to be able to image the bottom surface of the workpiece W via the external reflective member D2.

[0109] As shown in Fig. 24, the transport device B may be configured by a roller conveyor. That is, the transport device B has a plurality of rollers B4 that rotate around a horizontal axis and a frame B5 that supports the rollers B4. A transport mechanism is configured by each roller B4 and an axis B6 that rotates each roller B4. A gap is provided between the rollers B4, B4 adjacent to each other in the transport direction. The code reader 1 is configured to be able to read the code attached to the bottom surface of the workpiece W through the gap between the rollers B4, B4 adjacent to each other in the transport direction.

[0110] Furthermore, the code reader 1 in this embodiment is not limited to the installation position described above, but can also be installed at the same height as the conveying surface or higher than the conveying surface, which allows it to be used to read codes attached to the side or top surface of the workpiece W in addition to codes attached to the bottom surface of the workpiece W.

[0111] (Another embodiment) The embodiment of the present invention is not limited to the above embodiment, and may be, for example, another embodiment as described below. In the following description of the other embodiment, the same members as those in the above embodiment are given the same reference numerals and description is omitted, and different parts are described in detail. In addition, it is possible to combine the above embodiment with the following other embodiment to obtain yet another embodiment. When combining the above embodiment with the following other embodiment, the position of the above embodiment and a part of the following other embodiment can also be combined.

[0112] The first example shown in FIG. 26 is an example in which the imaging unit 30 of the code reader 1 has a first imaging unit 30a and a second imaging unit 30b. The first imaging unit 30a has a first image sensor 30c and a first optical system 30d. The first image sensor 30c has a two-dimensional light receiving surface for forming a predetermined field of view, and is a member that generates an image corresponding to an image projected on the light receiving surface through a light receiving window (also called a transmission window) 67. The light receiving window 67 is made of a transparent member having a short side extending in the short direction and a long side extending in the long direction. The first optical system 30d is a member that is interposed between the light receiving window 67 and the light receiving surface of the first image sensor 30c, and projects an image corresponding to the code attached to the work W in the housing 60 onto the light receiving surface of the first image sensor 30c. The first optical system 30d forms an optical path in which the optical axis passing through the center of the field of view is inclined with respect to the direction of the long side, and is longer in the direction of the long side than in the direction of the short side. The field of view and depth of the first imaging unit 30a can be set by various parameters of the first optical system 30d.

[0113] The second imaging unit 30b has a second image sensor 30e and a second optical system 30f. The second image sensor 30e has a two-dimensional light receiving surface for forming a predetermined field of view, and is a member that generates an image corresponding to an image projected on the light receiving surface through the light receiving window 67. The second optical system 30f is a member that is interposed between the light receiving window 67 and the light receiving surface of the second image sensor 30e, and projects an image corresponding to the code attached to the work W in the housing 60 onto the light receiving surface of the second image sensor 30e. The second optical system 30f forms an optical path that is long along the longitudinal direction of the light receiving window 67 and whose optical axis passing through the center of the field of view is inclined with respect to the longitudinal direction. The field of view and depth of the second imaging unit 30b can be set by various parameters of the second optical system 30f. The optical axis of the first imaging unit 30a and the optical axis of the second imaging unit 30b are in a close relationship.

[0114] The field of view and depth of the first imaging unit 30a are different from those of the second imaging unit 30b. Specifically, the field of view and depth of the first imaging unit 30a are within a range surrounded by a dashed frame indicated by reference symbol 8A in FIG. 26 (referred to as a first range). Various parameters of the first optical system 30d are set so as to be within the first range 8A. On the other hand, the field of view and depth of the second imaging unit 30b are within a range surrounded by a solid frame indicated by reference symbol 8B in FIG. 26 (referred to as a second range). Various parameters of the second optical system 30f are set so as to be within the second range 8B.

[0115] The first range 8A is set to include an area farther away than the second range 8B, and the farthest viewing range A1 of the first range 8A is expanded more than the farthest viewing range A2 of the second range 8B. The second range 8B is set to include an area closer than the first range 8A. The first image sensor 30c and the second image sensor 30e are provided to expand the viewing field and depth of the imaging unit 30. In short, the imaging unit 30 has the first image sensor 30c and the second image sensor 30e for expanding the viewing field and depth in the depth direction perpendicular to the plane forming the light receiving window 67 in the imaging viewing field. By expanding the viewing field and depth, a range (reading area) in focus is set as shown by the reference numeral 9. Note that a third imaging unit may be provided in addition to the first imaging unit 30a and the second imaging unit 30b. In this case, the viewing field and depth of the first imaging unit 30a, the second imaging unit 30b, and the third imaging unit can be configured to be different from each other.

[0116] The first imaging section 30a can be called a far-distance imaging section because it is an imaging section capable of imaging a farther side than the second imaging section 30b. Conversely, the second imaging section 30b can be called a near-distance imaging section because it is an imaging section capable of imaging a closer side than the first imaging section 30a. In this way, the imaging section 30 includes a near-distance imaging section that images the near side and a far-distance imaging section that images the far side. When a third imaging section is provided, the third imaging section can be, for example, a near-distance imaging section.

[0117] The code reader 1 further includes a light amount reducing member 30g that reduces the amount of light incident on the second image sensor 30e of the second imaging section 30b, which is the near side imaging section, thereby reducing the difference in the amount of light incident on the first image sensor 30c of the first imaging section 30a, which is the far side imaging section. The light amount reducing member 30g is composed of a neutral density filter (e.g., an ND filter) provided in the second optical system 30f of the second imaging section 30b. The amount of light attenuation by the neutral density filter can be set arbitrarily. The light amount reducing member 30g may be provided as necessary, and may be omitted.

[0118] FIG. 27 shows a second example, which is the same as the first example in that the imaging unit 30 has the first imaging unit 30a and the second imaging unit 30b, but the field of view and depth of the first image sensor 30c and the second image sensor 30e are different from those of the first example. Also, the optical axis of the first imaging unit 30a and the optical axis of the second imaging unit 30b are in a positional relationship farther away than in the first example. That is, in the second example, the first range 8A is located below the second range 8B and is set to include an area farther away than the second range 8B. The field of view and depth of the imaging unit 30 are expanded by the farthest field of view A1 of the first range 8A and the farthest field of view A2 of the second range 8B. In the second example, the optical path of the first imaging unit 30a and the optical path of the second imaging unit 30b do not coincide with each other, so that a part of the light receiving window 67 corresponds to the optical path of the first imaging unit 30a, and the other part corresponds to the optical path of the second imaging unit 30b. In this case, the light amount reducing member 30g can be configured with a neutral density filter provided in a portion of the light receiving window 67 corresponding to the optical path of the second imaging unit 30b. This can reduce the difference in the amount of light between the amount of light incident on the second image sensor 30e of the second imaging unit 30b and the amount of light incident on the first image sensor 30c of the first imaging unit 30a. In the second example, a neutral density filter may be provided in the second optical system 30f as in the first example.

[0119] Fig. 28 is a schematic diagram of a code reader 1 according to a third example of another embodiment. The third example also has a first imaging section 30a and a second imaging section 30b. In the third example, the first imaging section 30a and the second imaging section 30b are arranged in parallel, and light from outside the housing 60 is incident on the first imaging section 30a and the second imaging section 30b via the first mirror 101 and the second mirror 102. With this configuration, it is possible to separate the optical axes of the first imaging section 30a and the second imaging section 30b from each other.

[0120] 29 is a schematic diagram of a code reader 1 according to a fourth example of another embodiment. This code reader 1 includes an external lighting unit 103 that is separate from the housing 60 in which the imaging unit 3 is stored. The external lighting unit 103 includes a light emitter such as a light emitting diode, and is connected to the lighting control unit 42 stored in the housing 60 via a connection line 104. The connection line 104 can be connected to one of a plurality of connectors 85 provided outside the housing 60. In other words, one of the plurality of connectors 85 serves as a connector for connecting the external lighting unit 103.

[0121] The external lighting unit 103 is controlled by the lighting control unit 42 so as to illuminate the workpiece W in synchronization with the imaging unit 3 stored in the housing 60. The illumination area 105 of the external lighting unit 103 is set to include the field of view 8 of the imaging unit 3.

[0122] 30 to 32 are diagrams showing the appearance of a code reader 1 according to a fifth example embodiment. In the description of the fifth example embodiment, the same members as those in the above-mentioned embodiment are denoted by the same reference numerals and description thereof will be omitted, and different portions will be described in detail.

[0123] The housing 60 according to the fifth example has a box-shaped case 600 that constitutes a part of the housing 60 and a lid-shaped case 610 that constitutes the other part of the housing 60, and the box-shaped case 600 and the lid-shaped case 610 are integrated to form the housing 60. The lid-shaped case 610 is a first housing component, and the box-shaped case 600 is a second housing component.

[0124] The box-shaped case 600 is a member constituting the first side surface 61, the third side surface 63, the fourth side surface 64, the upper surface 65, and the lower surface 66, and is made of resin by molding a resin material. The box-shaped case 600 is a member constituting the portion other than the second side surface 62, and therefore has a shape in which the second side surface 62 side is open. The lid-shaped case 610 is a member constituting the second side surface 62, and is made of metal. Examples of the metal material constituting the lid-shaped case 610 include metal materials with high heat transfer coefficients, such as aluminum alloys. For this reason, the lid-shaped case 610 has better heat dissipation properties than the box-shaped case 600. On the other hand, the resin material constituting the box-shaped case 600 has a lower specific gravity than the metal material constituting the lid-shaped case 610, but is inferior in heat dissipation properties. For this reason, the weight of the box-shaped case 600 can be reduced.

[0125] The lid-like case 610 is attached to the box-like case 600 so as to cover the open portion of the box-like case 600. FIG. 33 shows a state in which the box-like case 600 is removed, and as shown in this figure, a main packing 611 made of an elastic material such as rubber or a thermoplastic elastomer is arranged on a joint surface 610a of the lid-like case 610 with the box-like case 600. The main packing 611 is formed in an annular shape along the periphery of the lid-like case 610, and is held in a state of being stored in a groove 600a formed in the box-like case 600 as shown in FIG. 34. The groove 600a of the box-like case 600 is a portion for storing the annular main packing 611, and is annular like the main packing 611 and is open to the lid-like case 610 side. Although not shown, the groove for storing the main packing 611 may be formed in the lid-like case 610.

[0126] The main packing 611 stored in the groove 600a is in close contact with the joint surface 610a of the lid case 610 in a state in which the lid case 610 is integrated with the box case 600. This creates a seal between the box case 600 and the lid case 610 by the main packing 611, preventing external water, etc. from penetrating into the housing 60.

[0127] As shown in Figs. 30 to 32, a first side surface 61 of the box-shaped case 600 is provided with a transmission window 620 that transmits light such as reflected light from the workpiece W and illumination light from the illumination unit 2. The longitudinal direction of the first side surface 61 is the vertical direction of the housing 60, and the longitudinal direction of the first side surface 61 is defined as a first direction. The transmission window 620 has an elongated shape along the first direction. The transmission window 620 is not particularly limited, and is made of, for example, acrylic, glass, polycarbonate, or the like.

[0128] A window frame 630 for fixing the transmission window 620 to the first side surface 61 of the box-shaped case 600 is provided on the first side surface 61 of the box-shaped case 600. The window frame 630 has a rectangular shape that is long in the vertical direction so as to correspond to the outer shape of the transmission window 620.

[0129] A window frame packing 631 (shown by phantom lines in FIG. 33) made of the same material as the main packing 611 is disposed on a joint surface (not shown) of the window frame 630 with the box-shaped case 600. The window frame packing 631 is formed in an annular shape along the periphery of the window frame 630, and is held in a stored state in a groove 630a formed in the window frame 630 as shown in FIG. 35. The groove 630a of the window frame 630 is a portion for storing the annular window frame packing 631, and therefore has an annular shape like the window frame packing 631 and is open to the box-shaped case 600 side. Although not shown, the groove for storing the window frame packing 631 may be formed in the box-shaped case 600.

[0130] Window frame packing 631 stored in groove 630a comes into close contact with the outer surface of transmission window 620 when window frame 630 is integrated with box-shaped case 600. This provides a seal between transmission window 620 and window frame 630 by window frame packing 631, preventing external water, etc. from penetrating into housing 60 through window frame 630.

[0131] The first image sensor 30c and the second image sensor 30e of the imaging unit 3 generate images corresponding to the image projected onto the light receiving surface through the transparent window 620. The first optical system 30d and the second optical system 30f of the imaging unit 3 form an optical path that is long along the longitudinal direction of the transparent window 620 and whose optical axis passing through the center of the field of view is inclined with respect to the longitudinal direction of the transparent window 620, and are configured to project an image corresponding to the code attached to the workpiece W inside the housing 60 onto the light receiving surface of each of the first image sensor 30c and the second image sensor 30e.

[0132] The illumination unit 2 is configured to form an illumination light path that is long along the longitudinal direction of the transmission window 620 and in which the optical axis of the illumination light is inclined with respect to the longitudinal direction of the transmission window 620. This allows the optical path of the illumination light emitted from the illumination unit 2 to correspond to the optical path of the imaging unit 3.

[0133] As shown in FIG. 30, the transmission window 620 has a first region 620a that transmits the illumination light irradiated from the illumination unit 2 to the outside of the housing 60, and a second region 620b that transmits the reflected light from the code attached to the workpiece W to the inside of the housing 60. That is, the illumination unit 2 is disposed so as to correspond to the left region of the transmission window 620 when the left-right direction of the transmission window 620 is taken as a reference, so that the illumination light irradiated from the illumination unit 2 passes through the left region of the transmission window 620. The left region of the transmission window 620 is the first region 620a so as to correspond to the arrangement position of the illumination unit 2. On the other hand, the reflected light from the code passes through the right region opposite to the illumination light when the left-right direction of the transmission window 620 is taken as a reference. The right region of the transmission window 620 is the second region 620b so as to correspond to the transmission region of the reflected light from the code. Since the first region 620a and the second region 620b are provided in one transmission window 620 in this manner, the number of parts is reduced compared to the case where separate window members are provided on the light projecting side and the light receiving side.

[0134] As shown in FIG. 33 and FIG. 36, a partition member (light-shielding member) 75 is provided inside the housing 60. The partition member 75 is a member for suppressing the illumination light irradiated from the illumination unit 2 from entering the optical system 31 of the imaging unit 3, and is formed so as to surround the illumination unit 2. A front side portion 75c of the partition member 75 is formed so as to approach the inner surface of the transmission window 620. An elastic material 76 (shown in FIG. 30) having light-shielding properties is interposed between the front side portion 75c of the partition member 75 and the inner surface of the transmission window 620. The elastic material 76 is made of, for example, a sponge material, and extends along the front side portion 75c of the partition member 75. By attaching the elastic material 76 in a state of being in close contact with the inner surface of the transmission window 620, it is possible to suppress the illumination light irradiated from the illumination unit 2 from passing near the inner surface of the transmission window 620 and entering the optical system 31 of the imaging unit 3.

[0135] 31, a plurality of heat dissipation fins 69 extending in the vertical direction (predetermined direction) are provided on the second side surface 62 side of the lid-like case 610. Since the longitudinal direction of the transmission window 620 is the vertical direction, the longitudinal direction of the heat dissipation fins 69 coincides with the longitudinal direction of the transmission window 620. The plurality of heat dissipation fins 69 are formed at intervals from one another in the depth direction (width direction) of the housing 60. The heat dissipation fins 69 are made of the same material as the portion constituting the second side surface 62, and therefore have a high thermal conductivity.

[0136] 31 and 37, the housing 60 is provided with a cover 640 that covers the tips of the heat dissipation fins 69. By covering the tips of the heat dissipation fins 69 with the cover 640, an air passage extending along the longitudinal direction of the transmission window 620 is formed between the second side surface 62 of the housing 60 and the heat dissipation fins 69 and the cover 640.

[0137] The code reader 1 includes a fan 70 for blowing air in the longitudinal direction of the heat dissipation fins 69. The heat dissipation fins 69 include a plurality of first heat dissipation fins 69a provided to correspond to an air passage through which the air blown by the fan 70 flows, and a plurality of second heat dissipation fins 69b provided to be located outside the air passage through which the air blown by the fan 70 flows. Specifically, among the plurality of heat dissipation fins 69 arranged in the depth direction of the housing 60, the plurality of heat dissipation fins located in the center of the arrangement direction are the first heat dissipation fins 69a. An air passage extending in the vertical direction is formed between the first heat dissipation fins 69a, and the fan 70 is disposed in the air passage between the first heat dissipation fins 69a. Moreover, among the plurality of heat dissipation fins 69 arranged in the depth direction of the housing 60, the plurality of heat dissipation fins on the front side and the plurality of heat dissipation fins on the back side are the second heat dissipation fins 69b. In this embodiment, the interval between the plurality of first heat dissipation fins 69a is set narrower than the interval between the plurality of second heat dissipation fins 69b. That is, the spacing between the heat dissipating fins 69a located in the portion where air is forcibly blown by the fan 70 is relatively narrow, so that the efficiency of heat dissipation to the air can be improved. The tip of the second heat dissipating fin 69b is not covered by the cover portion 640 and is open, so that heat dissipation from the second heat dissipating fin 69b can be promoted by utilizing natural convection of air. The spacing between the first heat dissipating fins 69a and the spacing between the multiple second heat dissipating fins 69b may be the same. The spacing between the heat dissipating fins can also be called the fin pitch.

[0138] The heat dissipation fins 69 are discontinuous in the longitudinal direction of the heat dissipation fins 69. Specifically, a cutout portion 69c is formed by cutting out a middle portion of the heat dissipation fins 69 in the longitudinal direction. As a result, the heat dissipation fins 69 are provided discontinuously in the vertical direction, so that even if the lower end of the heat dissipation fins 69 comes into close contact with some member and the air passage is blocked, the air blown into the air passage can escape to the outside through the cutout portion 69c, and a decrease in cooling efficiency can be suppressed.

[0139] As shown in Figures 38 and 39, a fan storage recess 612 is provided in a portion of the lid case 610 where the fan 70 is disposed. The fan storage recess 612 is formed in a portion of the lid case 610 that constitutes the second side surface 62, and is open to the left side. A portion of the fan 70 attached to the lid case 610 is stored in the fan storage recess 612. This allows a portion of the fan 70 to be stored in the lid case 610, so that a large-diameter fan 70 can be employed while reducing the amount of protrusion of the fan 70 to the left, and as a result, the left-right dimension of the code reader 1 can be shortened.

[0140] 36, the near-use light emitting board 2c constituting a part of the illumination unit 2 is attached to the lid-shaped case 610 via a near-side support member 71 having thermal conductivity. The far-use light emitting board 2f is attached to the lid-shaped case 610 via a far-side support member 72 having thermal conductivity. This allows heat from the near-use light emitting board 2c and the far-use light emitting board 2f to escape to the lid-shaped case 610 and be released by the heat dissipation fins 69.

[0141] The control board 90 is provided with a control unit 4 (shown in FIG. 2). The control unit 4 is a part that executes a decoding process of the code attached to the workpiece W based on the image generated by the image sensor 31b, and therefore the temperature rises during operation. The control board 90 on which the control unit 4 is provided is attached to the lid-shaped case 610 via a thermally conductive board support member 73. This allows the heat of the control board 90 to be dissipated to the lid-shaped case 610 and released by the heat dissipation fins 69.

[0142] 40 shows an insertion portion of the fan cable 70a for supplying power to the fan 70. The fan cable 70a extends from the inside to the outside of the housing 60 and is then connected to a motor (not shown) of the fan 70, so a hole 613 is formed in the lid-like case 610 as an insertion portion for inserting the fan cable 70a. With the fan cable 70a inserted through the hole 613, the hole 613 is blocked with an adhesive or the like. This makes it possible to prevent water from entering through the hole 613.

[0143] 41 to 43 show a lens holder 300 that holds a lens 31a of the imaging unit 3. The lens holder 300 has a fixing part 300a that is fixed to a lid-like case 610, and also has a tilt adjustment mechanism for the image sensor 31b. Specifically, a sensor board 301 as shown in FIG. 41 and a sensor holder 302 as shown in FIG. 42 are attached to the lens holder 300. The sensor board 301 is a member to which the image sensor 31b is fixed. The sensor board 301 is fixed to the sensor holder 302.

[0144] The above-described multiple alternative embodiments may each be an independent form, but it is also possible to form an embodiment in which any multiple alternative embodiments are combined with each other among the multiple alternative embodiments.

[0145] Furthermore, the present invention is not limited to a code reader. For example, a part of the present invention can be applied to a case where a control unit is configured not to execute code decoding processing. In this case, the image processing device processes the image acquired by imaging the work W transported by the transport device B, and the control unit is a part that executes various image processing. Examples of various image processing include OCR processing and image inspection processing. [Industrial Applicability]

[0146] As described above, the code reader according to the present disclosure can be used, for example, to read a code attached to a workpiece. [Explanation of symbols]

[0147] 1 Code Reader 2. Lighting section 3. Imaging unit 4. Control section 6. Communications Department 31 Scheimpflug Optical System 31a Lens 31b Image sensor 60 Case 61 First aspect 62 Second aspect 67 Light receiving window 83 Internal reflective material 85 Connector part B. Conveyor device B1 Upstream transport mechanism B2 Downstream transport mechanism D Mirror (external reflective material) W work

Claims

1. A code reader that reads a code attached to a workpiece transported by a transport device, An illumination unit that irradiates illumination light onto the workpiece; An imaging unit having a Scheimpflug optical system consisting of a lens that collects reflected light from a code attached to a workpiece and an image sensor having a light receiving surface inclined with respect to the optical axis of the lens, generating and outputting an image based on the amount of light received on the light receiving surface; A control unit that executes a decoding process on the code attached to the work based on the image output from the imaging unit; a housing that houses the illumination unit, the imaging unit, and the control unit and has a light receiving window that transmits the reflected light therein; the light receiving window is provided on a first side surface of the housing and has a short direction and a long direction; a plane formed by the light receiving window intersects with a plane including a focal plane formed by the Scheimpflug optical system so as to extend from the near side to the far side of the imaging unit, A code reader, wherein when viewed from a direction directly opposite the light receiving window, the illumination unit is disposed adjacent to the light receiving window in the short side direction.

2. 2. The code reader according to claim 1, the illumination unit includes a near illumination unit having an optical axis intersecting the focal plane on the near side of the focal plane relative to the far side, and a far illumination unit having an optical axis intersecting the focal plane on the far side of the focal plane relative to the near side, a region where the illumination light from the near distance illumination section and the illumination light from the far distance illumination section overlap on the focal plane is biased toward the far distance side relative to the near distance side.

3. 2. The code reader according to claim 1, the illumination unit includes a near illumination unit having an optical axis intersecting the focal plane on the near side of the focal plane relative to the far side, and a far illumination unit having an optical axis intersecting the focal plane on the far side of the focal plane relative to the near side, A code reader, wherein the luminous flux of the far-distance illumination section is greater than the luminous flux of the near-distance illumination section.

4. The code reader according to claim 2 or 3, a near-distance illumination unit having an optical axis angle with respect to the focal plane that is larger than an optical axis angle with respect to the focal plane of the far-distance illumination unit; the near-distance illumination unit and the far-distance illumination unit being disposed adjacent to each other in a direction from the first side surface toward the inside of the housing, and the near-distance illumination unit being disposed on the first side surface side.

5. The code reader according to claim 4, The housing further has a lower surface adjacent to the first side surface, an inclination angle of a far-field use light emitting substrate of the far-field use illumination unit with respect to the lower surface is larger than an inclination angle of a near-field use light emitting substrate of the near-field use illumination unit with respect to the lower surface, The long-distance light emitting board is disposed higher than the near-distance light emitting board with respect to the lower surface.

6. 2. The code reader according to claim 1, The housing further includes a partition member that is disposed between the illumination unit and the imaging unit and optically separates the illumination unit from the imaging unit.

7. 2. The code reader according to claim 1, The code reader further includes a heat dissipation unit, the heat dissipation unit is provided adjacent to the illumination unit of the housing and thermally connected to the illumination unit, and is disposed on a second side surface of the housing adjacent to the first side surface and having an area larger than that of the first side surface; The illumination unit has a light emitting substrate on which one or more light emitting elements are arranged, the code reader further includes a support member that supports the light emitting substrate, extends in a direction intersecting with the second side surface, and has thermal conductivity; The support member is thermally connected to the light emitting board and the heat dissipation portion.

8. The code reader according to claim 7, The code reader further includes a control board on which the control unit is provided, the control board is disposed on an inner wall of the housing on the second side surface side, The heat dissipation unit is thermally connected to the control board.

9. 2. The code reader according to claim 1, The code reader further includes an internal reflection member that is stored in the housing and reflects light incident on the imaging unit, the imaging unit is disposed near one end in the longitudinal direction within the housing, The illumination unit and the internal reflection member are disposed near the other end in the longitudinal direction within the housing.

10. 10. The code reader according to claim 9, The code reader further includes a connector portion that is connected to an external device. A code reader, wherein the illumination portion and the internal reflection member are disposed between the light receiving window and the connector portion.

11. 10. The code reader according to claim 9, The code reader further includes a communication unit that receives dimensions of gaps formed between a plurality of conveying mechanisms of the conveying device and a conveying speed of the conveying device, The control unit determines a frame rate of the imaging unit based on the size of the gap and the transport speed.

12. 10. The code reader according to claim 9, the image sensor has a plurality of image pickup elements arranged in a row direction and a column direction, the row direction corresponding to a direction from the near side to the far side of a focal plane of the Scheimpflug optical system, an aspect ratio of the image sensor is smaller than an aspect ratio of the light receiving window; The image sensor is configured to be able to partially output signals from imaging elements in a row corresponding to the light receiving window, among the plurality of imaging elements.

Images