Light shielding structure for optical information reader having explosion-proof function

Abstract

To improve the accuracy of optical information reading by preventing excessive internal light reflection from a light transmission window from being made incident on the light receiving part of a sensor part arranged inside a casing provided with the light transmission window in an optical information reader provided with an explosion-proof function.SOLUTION: Between the light receiving unit and the light projecting unit of the sensor unit, a light shielding material for preventing irradiated light from the light projecting unit from being reflected by the light transmission window and entering the light receiving unit is erected so as to surround the light receiving unit and is configured to abut on the light transmission window, and the light shielding material is provided with an opening to such an extent that reflected light from the optical information recording medium facing the outside of the light transmission window by the irradiated light from the light projecting unit is not prevented from entering the light receiving unit.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a light-shielding structure for an optical information reading device with an explosion-proof function, and more specifically, to an optical information reading device having a housing with at least a light-transmitting window and a sensor unit arranged inside the housing facing the light-transmitting window, in which the light-shielding structure for an optical information reading device with an explosion-proof function improves the accuracy of optical information reading by blocking excess internal light reflection from the light-transmitting window to the sensor unit with a light-shielding material. [Background technology]

[0002] In environments where flammable gases or dust are handled or where these may be generated during the manufacturing or processing of products, there is a risk of fire or explosion due to sparks or static electricity generated by the use of electrical appliances.

[0003] Therefore, the law defines such environments as "hazardous locations" based on specified conditions in accordance with labor safety regulations and standards for explosion-proof structures for electrical machinery and equipment, and provides for several classifications based on the degree of danger, with specific measures to be taken.

[0004] Therefore, optical information readers, which are electrical appliances, also require explosion-proof and dust-proof measures according to the level of danger in order to prevent disasters from occurring in such hazardous locations.

[0005] As a countermeasure against explosion and dust, the optical information reader may be housed in an explosion-proof case or may be provided with an explosion-proof function in itself.

[0006] Figure 1 shows an example of an optical information reader in which the entire housing including the explosion-proof case has explosion-proof functionality by storing the optical information reader in such an explosion-proof case, and shows the light-emitting unit and light-receiving unit (sensor unit) of the optical information reader and the light-transmitting window of the explosion-proof case located opposite them.

[0007] Here, more specifically, FIG. 1 is a cross-sectional view showing the main parts of a light-transmitting window 110 provided in an explosion-proof case 100 and a sensor unit 130 arranged inside the light-transmitting window 110, and shows an example in which a light-receiving unit 135 is arranged in the center of the sensor unit 130 and multiple light-emitting units 133 are arranged around it.

[0008] 1, a light-transmitting window 110 of the explosion-proof case 100 is provided opposite the sensor unit 130 of the optical information reader. Therefore, light emitted from the light-emitting unit 133 of the sensor unit 130 passes through the light-transmitting window 110 of the explosion-proof case 100 and, for example, as shown by the dashed arrow in FIG. 2, is irradiated onto the entire optical information recording medium such as a barcode BC attached to a product 800 or the like that is presented or placed facing the outside of the light-transmitting window 110 of the explosion-proof case 100, and the light (data light) containing information (data) such as the barcode BC reflected therefrom passes through the light-transmitting window 110 again and reaches the light-receiving unit 135 of the sensor unit 130.

[0009] However, when such a configuration is adopted, for example, as shown by the bold dotted arrow in Figure 1, part of the light emitted from the light-emitting part 133 of the sensor 130 may be reflected (internal light reflection) by the back surface 110B of the light-transmitting window 110 of the explosion-proof case 100 and enter the light-receiving part 135 of the sensor 130.

[0010] In particular, in the case of a light-transmitting window 110 having an explosion-proof function, a thick window is often used to achieve the explosion-proof function, so such internal light reflection may occur not only on the back side 110B as illustrated in Figure 1, but also on the front side 110F.

[0011] If such internal light reflection occurs, the reflected light due to internal light reflection will be incident on the light receiving unit 135 of the optical information reading device together with the data light, which may have harmful effects such as reducing the contrast of the data light and lowering the signal-to-noise ratio (s / N ratio) of the information obtained by the light receiving unit 135.

[0012] Therefore, as a means for preventing excess light from entering the light receiving section of the sensor section of the optical information reading device, a light blocking means may generally be provided, such as those described in Patent Publication No. 2002-1183658 (Patent Document 1) and Patent Publication No. 60-206265 (Patent Document 2). [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-183658 [Patent Document 2] Japanese Patent Publication No. 60-206265 Summary of the Invention [Problem to be solved by the invention]

[0014] The technology described in Patent Document 1 aims to "optimally control the irradiated light and reflected light without increasing the number of optical elements used in barcode reading devices, thereby preventing the inclusion of unnecessary ambient light and improving the S / N ratio" (see "Abstract" of Patent Document 1).

[0015] In the invention described in Patent Document 1, "a dust filter 31 for the laser beam irradiated light Li and a dust filter 33 for the reflected light Lr are separated and fixed to the cover 16 by a dust filter fixing member 32 for irradiated light and a dust filter fixing member 34 for reflected light, respectively. In addition, the light receiving element fixing member 24 covers the area other than the light receiving surface of the light receiving part 3a of the light receiving element 3 with the portion other than the through hole 24a, thereby blocking light" (see "Abstract" of Patent Document 1).

[0016] However, in the case of the technology described in Patent Document 1, the irradiation light Li of the laser beam emitted from the irradiation light protection filter 31 reaches the barcode section 1 directly, and there is no structure between them such as a light-transmitting window as envisaged by the present invention.

[0017] Therefore, even if the aperture portion 32a of the fixing member 32 for irradiated light and the aperture portion 34a of the fixing member 34 for dustproof filter for reflected light have a certain light-blocking effect, it is not possible to eliminate the harmful effects that internal light reflection has on the light-receiving portion of the optical information reading device, as envisioned by the present invention.

[0018] Furthermore, as shown in Figure 1 of Patent Document 2, the technology of Patent Document 2 aims to "block the stray light and allow only the light reflected from the linear reading portion necessary for reading the document to be incident, in order to obtain a stable light amount without stray light, by "blocking the stray light and allowing only the light reflected from the linear reading portion necessary for document reading to be incident, in order to obtain a stable light amount without stray light" since "light rays emitted from the light source, such as light ray 20c, do not illuminate the linear reading portion 13 of the document 1 but illuminate the peripheral portion thereof, and the reflected light is incident on the rod lens 4, or light source 20b does not illuminate the document 1 but directly enters the rod lens 4, in order to obtain a stable light amount without stray light" (see Patent Document 2, page 2, upper right to lower right columns).

[0019] Therefore, the technology of Patent Document 2 employs a structure in which "an optical device consisting of a light source for illuminating an original document, a rod lens array for concentrating reflected light from the original document, and an image sensor in which one or more photoelectric conversion elements are arranged in a line at the point where the reflected light is focused by the rod lens array, and a light shielding plate for removing stray light is provided between the light source and the rod lens array" (see Patent Document 2, page 2, top right column to bottom left column).

[0020] However, the present invention aims to irradiate light from a thick light-transmitting window onto the entire optical information recording medium BC, which is positioned at a certain distance, as illustrated in Figure 2, and read the reflected light from the entire recording medium. This is fundamentally different from the technology described in Patent Document 2, which focuses light on a linear area of ​​an original placed on a glass platen and attempts to read the information in that area, and therefore cannot adopt a light-blocking structure that is specialized for such a partial area.

[0021] Furthermore, in the case of the technology described in Patent Document 2, information is read by dividing it into linear sections, so in order to read the entire information, the reading unit including the photoelectric conversion element 6 and the original 1 are structured to move (scan) relative to each other, and a gap is required between the light-shielding unit and the glass surface, making it difficult to effectively prevent internal reflections from entering through the gap.

[0022] Furthermore, the explosion-proof structure envisioned for use in this invention does not anticipate the use of something like a rod lens between the light-emitting unit and the light-receiving unit, nor is it conceivable to use a light-blocking material between the rod lens and the light-emitting unit.

[0023] Therefore, the present invention has been made in consideration of the circumstances described above, and an object of the present invention is to improve the accuracy of optical information reading in an optical information reading device with explosion-proof function by preventing unnecessary internal light reflection from a light-transmitting window from entering the light receiving section of a sensor section arranged inside a housing with the light-transmitting window. [Means for solving the problem]

[0024] In order to solve the above problems, the present invention provides a light-shielding structure for an optical information reading device with explosion-proof capabilities, characterized in that in an optical information reading device with explosion-proof capabilities, the optical information reading device comprises at least a housing with a light-transmitting window and a sensor unit arranged inside the housing facing the light-transmitting window, the sensor unit comprises a light-receiving unit and a plurality of light-emitting units around the light-receiving unit, and between the light-receiving unit and the light-emitting unit, a light-shielding material that prevents the light irradiated from the light-emitting unit from being reflected by the light-transmitting window and entering the light-receiving unit is erected so as to surround the light-receiving unit and is configured to abut against the light-transmitting window, and the light-shielding material has an opening that is large enough not to prevent reflected light from an optical information recording medium facing the outside of the light-transmitting window due to the light irradiated from the light-emitting unit from entering the light-receiving unit.

[0025] Furthermore, the above problem can be solved even more effectively by using a sliding material in the contact portion of the light-blocking material with the light-transmitting window, or by having the light-blocking material be ring-shaped with a cross section having an outline that is approximately a truncated cone, with the light-transmitting window side as the lower base, or by having the light-blocking material be ring-shaped with a cross section having an outline that is approximately a truncated polygonal pyramid, with the light-transmitting window side as the lower base and having one side corresponding to the number of light-projecting units, or by having the optical information reading device be an optical barcode reader. [Effects of the Invention]

[0026] 3, in the light-shielding structure of an optical information reader with explosion-proof function according to the present invention, a sensor unit 130 is disposed inside a housing 100 having a light-transmitting window 110, facing the light-transmitting window 110. Between the light-receiving unit 135 and the light-emitting unit 133 constituting the sensor unit 130 disposed in this manner, a light-shielding material 150 is provided so as to surround the light-receiving unit 135 and abut against the light-transmitting window 110, preventing the light emitted from the light-emitting unit 133 from being reflected by the light-transmitting window 110 and entering the light-receiving unit 135.

[0027] Therefore, in the present invention, by adopting the above-mentioned light-shielding structure, it is possible to effectively prevent reflected light due to excess internal light reflection from the light-transmitting window from entering the light-receiving section of the sensor unit, thereby improving the accuracy of optical information reading. [Brief explanation of the drawings]

[0028] [Figure 1] 3 is a cross-sectional view showing the main parts of a light-transmitting window provided in an explosion-proof case and a sensor unit arranged inside the light-transmitting window. FIG. [Figure 2] This is a front view including a partial perspective view showing the positional relationship between an optical information reading device with an explosion-proof function and an optical information recording medium attached to a product, etc. that is presented or placed facing the outside of the light-transmitting window of the optical information reading device. [Figure 3] This is a cross-sectional view, similar to Figure 1, showing a light-transmitting window provided in an explosion-proof case, the main part of a sensor unit arranged inside the light-transmitting window, and a light-shielding material that stands from the sensor unit to the light-transmitting window and abuts against it. [Figure 4] 1 is a perspective view showing an example of the main components of an optical information reader having an explosion-proof function according to the present invention; [Figure 5] FIG. 1 is a perspective view showing an example of an optical information reading device including a sensor unit. [Figure 6] These are perspective views including partial perspective views showing examples of the configuration of a light-blocking material, where (A) shows an example in which the cross section is configured in a ring shape with an outline of an approximately polygonal truncated pyramid, and (B) shows an example in which the cross section is configured in a ring shape with an outline of an approximately truncated cone and has a cutout portion on part of the outer surface. DETAILED DESCRIPTION OF THE INVENTION

[0029] The light-shielding structure of an optical information reader with an explosion-proof function according to the present invention will be described in more detail below with reference to the drawings.

[0030] The drawings referred to below are intended to illustrate an outline of the configuration of the present invention, and the detailed structures, proportions, and notations of common structures may be exaggerated or omitted in a schematic manner to facilitate understanding.

[0031] Furthermore, the present invention relates to a light-blocking structure for an optical information reader with an explosion-proof function, and as long as it has an explosion-proof function (or dustproof function), it does not matter what kind of explosion-proof structure it has. Therefore, the optical information reader itself may have an explosion-proof function, or the optical information reader itself may not have an explosion-proof function but may become an optical information reader with an explosion-proof function by being housed in an explosion-proof case or the like.

[0032] And, regardless of what kind of explosion-proof structure is adopted, since the present invention relates to an optical information reading device, it is necessary to provide a light-transmitting window for transmitting light emitted from the light-emitting part of the sensor part and reflected light incident on the light-receiving part of the sensor part from an optical information recording medium attached to a product, etc. And, in the present invention, the sensor part of the optical information reading device is basically provided inside the light-transmitting window, and a light-shielding material is erected between the light-transmitting window and the sensor and abuts against the light-transmitting window.

[0033] Therefore, in the following description, the light-transmitting window will be mainly described first, followed by a description of the sensor section and the light-shielding material. (Light transmission window) First, the light-transmitting window in the light-shielding structure of the optical information reader with explosion-proof function according to the present invention will be described.

[0034] The light-transmitting window 110 of the optical information reading device with explosion-proof function according to the present invention is provided, for example, as shown in FIG. 4, in an explosion-proof case (housing) 100 or in the optical information reading device itself, and is used to provide explosion protection for the equipment stored inside the housing 100 on the inside of the light-transmitting window 110, as well as to transmit light emitted from the sensor section 130 of the optical information reading device and to transmit light reflected from the optical information recording medium.

[0035] For this reason, the light-transmitting window 110 is basically made of a material such as light-transmitting tempered glass or transparent engineering plastic. The light-transmitting properties are intended to transmit light from the light-projecting unit 133 of the sensor unit 130 of the optical information reader and light reflected from the optical information recording medium BC, and while providing an explosion-proof function, a material that has good transmittance for not only visible light but also infrared and ultraviolet rays is selected depending on the type of light irradiated from the light-projecting unit 133. In order to enhance these light transmittances, the front and back surfaces of the light-transmitting window 110 may be coated to suppress light reflection.

[0036] Furthermore, the light-transmitting window 110 is configured to be thick in order to achieve an explosion-proof function, and is basically circular in shape, and for ease of handling, a ring-shaped frame 110R is provided around the periphery, as shown in Fig. 4. Therefore, the light-transmitting window 110 is configured to be attached to a housing such as the explosion-proof case 100 via the ring-shaped frame 110R.

[0037] 4, the ring-shaped frame 110R is configured to surround the periphery of a material such as tempered glass that constitutes the light-transmitting window 110, and has a screw thread (or screw groove) 110Rt formed on its lower part, and is configured so that, for example, as shown by the arrow in FIG. 4, by fitting the ring-shaped frame 110R into the protective case 100 while rotating it, the screw thread engages with a screw groove (or screw thread) 100g formed on the protective case 100 and screws into the protective case 100. Therefore, when the ring-shaped frame 110R is screwed and fitted into the protective case 100, it is possible to employ a structure in which a sliding member 151 is provided on the light-blocking member 150 at the portion that comes into contact with the light-blocking member 150 provided on the sensor unit 130 of the optical information reader, as will be described later, so that the screwing proceeds smoothly.

[0038] Therefore, in the present invention, by providing such a light-transmitting window 110, it is possible to achieve explosion-proof and dust-proof functions for the equipment housed inside the housing 100 inside the light-transmitting window 110, and to efficiently project and receive light in the sensor unit 130.

[0039] In the above example, the light-transmitting window 110 is shown to have a circular shape, but this shape is not particularly limited, and it can also be rectangular or polygonal depending on the light projection range or light reception range of the sensor unit 130.

[0040] Similarly, the shape of the frame 110R surrounding the light-transmitting window 110 can be selected arbitrarily depending on the shape of the window, and the attachment of the frame 110R to the protective case 100 or the like is not limited to the screwing means described above. It is also possible to provide an engagement portion between the frame 110R and the protective case 100 or the like, which has an engagement means for mutual engagement such as a bolt and nut (not shown), and attach the frame 110R via the engagement portion. (About the sensor part) Next, a sensor portion in the light-shielding structure of the optical information reader with explosion-proof function according to the present invention will be described.

[0041] 2, the sensor unit 130 of the optical information reader main body 101 is disposed inside the protective case 100 of the optical information reader having an explosion-proof function, and has the basic function of irradiating light onto an optical information recording medium BC such as a barcode attached to a product 800 or the like, which is located at a certain distance from the transmission window 110, and reading data from the optical information recording medium BC contained in the reflected light. Therefore, the optical information reading device main body 101 including the sensor unit 130 can be connected to an information processing device (not shown) that processes information acquired by the sensor unit 130, and various input / output devices.

[0042] The specific form of the sensor unit 130 is not particularly limited as long as it has the basic functions described above, but for example, as illustrated in FIG. 5, the sensor unit 130 constitutes a part of the optical information reading device main body 101, and has a form in which a light receiving unit 135 is arranged in the center and multiple light emitting units 133 are arranged around it.

[0043] Furthermore, the light projecting section 133 of the sensor section 130 is provided with an optical oscillation element such as a semiconductor laser, and the plurality of light receiving sections 135 are provided with optical imaging elements such as CCD or CMOS sensors.

[0044] In the present invention, such a sensor unit 130 is arranged inside a light-transmitting window 110 provided in an explosion-proof case 100 or the like, as shown in Figures 3 and 4, so as to face the light-transmitting window 110.In this case, based on the standards, laws, etc. of the explosion-proof case 100, a distance of 15 mm or more to 50 mm or more may be adopted from the light-transmitting window that forms the inner wall of the housing 100 in accordance with the laws, etc.

[0045] Therefore, by providing such a sensor unit 130, in the present invention, as illustrated in Figure 2, etc., light projected from the sensor unit 130 passes through a transparent window 110 of the explosion-proof case 100, etc., and is irradiated onto an optical information recording medium BC attached to a product, etc. 800, and the reflected light passes through the light-transmitting window 110 and reaches the sensor unit 130, and the optical information from the reflected light is processed inside the optical information reading device or by an information processing device, etc. connected to it (not shown), and the required information can be obtained by an output device.

[0046] Here, there is no particular limitation on the type of optical information recording medium BC that the sensor unit 130 reads, and therefore it is not limited to barcodes or two-dimensional barcodes attached to products, etc., but may also include symbols, signs, letters, numbers, etc., or information for the purpose of visual inspection of the product itself, such as for checking for forgotten screws inside the product, etc. (About light blocking materials) Next, the light-shielding material 150 in the light-shielding structure of the optical information reader with explosion-proof function according to the present invention will be described.

[0047] The light-shielding material 150 in the present invention is a material for preventing the light emitted from the light-emitting unit 133 from being reflected by the front surface 110F or the back surface 110B of the light-transmitting window 110 and entering the light-receiving unit 135, and is provided, for example, between the light-transmitting window 110 and the sensor unit 130, as shown in Figures 3 and 4.

[0048] The light-shielding material 150 is arranged between the light-receiving unit 135 and the light-emitting unit 133 of the sensor unit 130 so as to surround the light-receiving unit 135, and is configured to stand in the direction of the light-transmitting window 110 and abut against the light-transmitting window 110.

[0049] Therefore, the shape of the light-blocking material 150 is not particularly limited as long as it is capable of blocking light that is reflected by the back surface 110B or the front surface 110F of the light-transmitting window 110 and enters the light-receiving unit 135. For example, as shown in Figure 3 or Figure 4, it can be formed into a ring shape with a cross-section that has an approximately truncated cone-shaped outline, that is, a ring shape that has an approximately truncated cone-shaped appearance but has a space that runs through from the upper base to the lower base and has a cross-section of a constant thickness. In this case, the upper base of the truncated cone is positioned to surround the light-receiving unit, and the lower base is configured to abut against the light-transmitting window.

[0050] It is desirable that the inner surface of the light-blocking material 150 be roughened or spirally processed around the axial direction to prevent light incident on the inner surface of the light-blocking material 150 from being diffusely reflected and entering the light-receiving unit 135.

[0051] In addition, the light-shielding material 150 provided as described above must have an opening large enough to prevent reflected light from the optical information recording medium BC facing the outside of the light-transmitting window 110 due to the light irradiated from the light-emitting section 133 of the sensor section 130 from entering the light-receiving section 135.

[0052] That is, the light-blocking structure of the optical information reading device according to the present invention aims to effectively prevent reflected light due to internal reflection from the light-transmitting window 110 while effectively acquiring reflected light from the optical information recording medium BC.

[0053] Therefore, when the above-mentioned truncated cone shape is adopted as the light-blocking material 150, the opening with the inclination angle θ of the truncated cone side of the light-blocking material 150 needs to be set to a degree that can prevent the light irradiated from the light-projecting unit 133 from being reflected by the light-transmitting window 110 and entering the light-receiving unit 135, as illustrated by the thick dotted arrow in Figure 3, while not preventing the reflected light from the optical information recording medium BC facing the outside of the light-transmitting window 110 due to the light irradiated from the light-projecting unit 133 from entering the light-receiving unit 135.

[0054] At this time, the size of the effective area formed by the number of effective pixels of the sensor used in the sensor unit 130 and the angle of view ω formed by the lens of the light receiving unit 135 are taken into consideration.

[0055] The opening at the inclination angle θ of the light-shielding material 150 from the sensor unit 130 to the light-transmitting window 110, taking into account the angle of view ω, is comprehensively determined based on, for example, the thickness d1 of the light-transmitting window 110, the distance d2 from the sensor unit 130 to the light-transmitting window 110, the distance D between the light-projecting unit 133 and the light-receiving unit 135, the field of view ω0 of the light-receiving unit 135, and the irradiation range γ of light from the light-projecting unit 133 (not shown).

[0056] Furthermore, the material of the light blocking material 150 is not particularly limited as long as it ensures light blocking properties, but it is possible to use rubber, silicone rubber, engineering plastic, or the like, which can maintain a certain shape.

[0057] Furthermore, since the light-blocking material 150 is provided upright from the sensor unit 130 toward the light-transmitting window 110, the portion that abuts against the light-transmitting window 110 may be configured to abut against the light-transmitting window 110 via a ring-shaped elastic body or slider 151, as shown in FIGS. 3 and 4 , and the portion that rises from the sensor unit may be configured to stably hold the overall shape to the sensor unit 130 via a ring-shaped adhesive or adhesive tape 153. Here, the slider 151 is used in consideration of the case where the light-transmitting window 110 is screwed to the case 100 or the like while rotating via the frame 110R, as described above. Therefore, by using such a slider 151, it is possible to prevent the light-blocking material 150 from being twisted and deformed when the light-transmitting window 110 is screwed to the case 100 or the like. On the other hand, when the light-transmitting window 110 is attached to the case 100 or the like via an appropriate engaging portion rather than by screwing, the sliding material 151 is not necessarily required, and an elastic material may be used to press the light-transmitting window 110 against the light-transmitting window 110 so that no gap occurs between the light-transmitting window 110 and the light-blocking material 150.

[0058] It is also possible to provide a flange (annular edge or brim) including the outer periphery of the light-shielding material 150 on one or both of the upper and lower truncated cone parts of the light-shielding material 150, and in that case, the above-mentioned elastic body, sliding body 151, adhesive tape 153, etc. may be provided on the flange part.

[0059] Furthermore, the shape of the light-blocking material 150 may be, depending on the number of light-transmitting units 133 arranged around the light-receiving unit 135 and the shape of the light-transmitting window 110, for example, as illustrated in FIG. 6(A), a ring-shaped upper surface having a cross-section that is approximately a polygonal truncated pyramid-shaped outline with at least one side corresponding to the number of light-transmitting units 133, i.e., a ring-shaped upper surface having a cross-section of a constant thickness and an approximately polygonal truncated pyramid-shaped appearance but with a space penetrating from the upper surface to the lower surface. In the present invention, the light-blocking material 150 does not necessarily have to be limited to a truncated cone-shaped cross-section as described above, as long as it abuts against the light-transmitting window 110 and is disposed between the light-transmitting unit 133 and the light-receiving unit 135 of the sensor unit 130 to prevent excess reflected light from the light-transmitting window 110. Therefore, although the upper surface is ring-shaped in the above description, it can be appropriately modified to match the shape of the opening of the light-receiving unit 135.

[0060] Therefore, according to the light-shielding structure of the optical information reading device with explosion-proof function of the present invention having the above-mentioned configuration, it is possible to prevent reflected light due to excess internal light reflection from the light-transmitting window from entering the light-receiving part of the sensor unit, thereby improving the accuracy of optical information reading.

[0061] The above configuration example shows an example of the light-shielding structure of an optical information reading device equipped with an explosion-proof function according to the present invention, and the configuration and form can be appropriately changed or added within the scope of the spirit of the present invention.

[0062] Therefore, as long as the device has an explosion-proof structure and a light-transmitting window as described above, the specific form of the explosion-proof structure is not important. Also, although the above mainly describes explosion-proof structures, the same can be applied to devices with dust-proof structures.

[0063] Furthermore, although the light-blocking material used in the above example is erected so as to surround the light-receiving unit, the purpose of providing the light-blocking material is to prevent internal reflection from the light-projecting unit to the light-receiving unit, so it does not necessarily have to surround the entire periphery of the light-receiving unit. Therefore, for example, as illustrated in Figure 6(B), a configuration such as providing a notch N on a part of the side surface of the light-blocking material may be provided in the area other than between the light-projecting unit and the light-receiving unit. [Explanation of symbols]

[0064] 100 Protective Case 100g Protective case screw groove 101 Optical information reading device body 110 Light-transmitting window 110F Light-transmitting window surface 110B Back side of light-transmitting window 110R ring-shaped frame 110Rt Ring-shaped frame thread 130 Sensor unit 133 Light projector 135 Light receiving part 150 Shade material 151 Sliding materials 153 Adhesive (Ring) 800 products etc. BC barcode (optical information recording medium) ω Angle of view of light transmission window ω0 Field of view of the light receiving part γ Irradiation range of light from the light projector (irradiation angle) θ The angle of inclination of the side of the shielding material d1 Thickness of the light-transmitting window d2 Distance from the sensor to the back of the light-transmitting window D Distance between the center of the light-emitting part and the center of the light-receiving part N Notch

Claims

1. In an optical information reader equipped with an explosion-proof function, The optical information reader includes at least a housing having a light-transmitting window, and a sensor unit disposed inside the housing so as to face the light-transmitting window, the sensor unit includes a light receiving unit and a plurality of light projecting units disposed around the light receiving unit, a light-shielding material that prevents the light emitted from the light-emitting unit from being reflected by the light-transmitting window and entering the light-receiving unit is provided between the light-receiving unit and the light-emitting unit, and is configured to stand around the light-receiving unit and abut against the light-transmitting window; the light-shielding material has an opening that does not prevent reflected light from the optical information recording medium facing the outside of the light-transmitting window, which is irradiated with light from the light-emitting unit, from entering the light-receiving unit. A light-shielding structure for an optical information reader having an explosion-proof function, characterized in that:

2. 2. The light-shielding structure for an optical information reader with explosion-proof function according to claim 1, wherein the light-shielding member uses a slidable material in a portion that abuts against the light-transmitting window.

3. 3. The light-shielding structure of an optical information reading device with explosion-proof function described in claim 1 or 2, wherein the shielding material is ring-shaped with a cross section having an approximately truncated cone shape with the light-transmitting window side as the lower base.

4. 3. The light-shielding structure of claim 1 or 2, wherein the shielding material is a ring-shaped member having a cross section with a substantially polygonal truncated pyramid-shaped outline, with the light-transmitting window side as the lower base and one side corresponding to the number of the light-projecting units.

5. 3. The light-shielding structure for an optical information reader with explosion-proof function according to claim 1, wherein the optical information reader is an optical barcode reader.

Images