Spectroscopic measurement device and article inspection device including the same

Abstract

To provide a spectroscopic measurement device and an article inspection device capable of increasing a light reception amount in a light detection section.SOLUTION: A spectroscopic measurement device includes: a light source section for emitting light to a tablet W being conveyed; a light detection section for measuring spectral characteristics of transmission light having passed through an optical fiber 41 by a spectrometer after the transmission light emitted from the light source section so as to pass through the tablet W is made incident to the optical fiber 41; and a reflection cover 5 disposed via a predetermined gap G with a front surface S of the tablet W and having a reflection surface 53 for reflecting the light having passed through the tablet W toward the front surface S of the tablet W. In the reflection cover 5, the reflection surface 53 is constituted by a curved surface of a spherical crown shape equal less than a hemisphere which extends toward the tablet W from an incident end surface 41a of the optical fiber 41.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a spectroscopic measurement device and an article inspection device. [Background technology]

[0002] Patent Document 1 discloses a spectroscopic measurement device that includes a light irradiation unit that irradiates a mounting surface on which an object to be measured is placed with broadband light from a light source via a light guide, and a light detection unit that inputs light that has passed through the object to a spectrometer via an optical fiber and measures the spectroscopic characteristics in the spectrometer, and that has a reflective cover that has a shape that expands from the incident surface of the optical fiber that receives the light that has passed through the object to the surface of the object, and has a reflective surface that reflects the light that has passed through the object to the surface of the object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7270582 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the spectroscopic measurement device described in Patent Document 1 has the following problem when measuring an object being transported: When measuring an object being transported, it is necessary to provide a gap between the object and the reflective cover to prevent the object from coming into contact with the reflective cover and causing wear on the object. If a gap is provided between the object and the reflective cover, the reflective cover will be separated from the surface of the object, reducing the effectiveness of the reflective cover.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a spectroscopic measurement device and an article inspection device that can increase the amount of light received by a light detection unit. [Means for solving the problem]

[0006] The spectroscopic measuring device of the present invention comprises a light source unit that irradiates light onto an object being transported, a light detection unit in which the transmitted light irradiated from the light source unit and transmitted through the object is incident on an optical fiber, and the light detection unit measures the spectral characteristics of the transmitted light that has passed through the optical fiber using a spectroscope, and a reflective cover that is arranged with a predetermined gap between it and the surface of the object facing the incident end face of the optical fiber and has a reflective surface that reflects the light that has transmitted through the object onto the surface of the object, and the reflective cover is configured with a curved surface in the shape of a spherical crown that is less than a hemisphere and extends from the incident end face toward the object.

[0007] With this configuration, the spectroscopic measuring device of the present invention is equipped with a reflective cover having a reflective surface that reflects light that has passed through an object onto the surface of the object, and the reflective surface of the reflective cover is composed of a curved surface that has a spherical crown shape that is less than a hemisphere and extends from the incident end surface toward the object.Therefore, even if there is a gap between the surface of the object and the reflective cover, the amount of light incident on the incident end surface of the optical fiber can be increased, and the amount of light received by the light detection unit can be increased.

[0008] In the spectroscopic measurement device according to the present invention, it is preferable that the reflective cover is arranged so that a center point at the same distance from the reflective surface is located on the surface of the article.

[0009] With this configuration, the spectroscopic measuring device of the present invention has a reflective cover positioned so that its center point, which is the same distance from the reflective surface, is located on the surface of the object, thereby further increasing the amount of light incident on the incident end face of the optical fiber.

[0010] An article inspection device according to the present invention includes the spectroscopic measurement device according to claim 1 or 2, and an inspection unit that inspects the quality of the article based on the spectroscopic characteristics measured by the spectroscope.

[0011] With this configuration, the article inspection device according to the present invention can increase the amount of light received by the light detection unit, thereby improving the signal level input to the inspection unit and improving the accuracy of inspection in the inspection unit. Furthermore, the improved signal level enables the article inspection device according to the present invention to perform measurements in a short time, thereby improving inspection throughput. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a spectroscopic measurement device and an article inspection device that can increase the amount of light received by a light detection unit. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of an article inspection device equipped with a spectroscopic measurement device according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a reflective cover of a spectroscopic measurement device according to one embodiment of the present invention. [Figure 3] FIG. 3 is a graph showing the change in the amount of light received by the light detection unit depending on the distance between the tablet and the reflective cover. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an article inspection device equipped with a spectroscopic measurement device according to one embodiment of the present invention will be described with reference to the drawings.

[0015] In this embodiment, when an item to be inspected is transported individually along a transport path by a transport unit and reaches a predetermined inspection position, the item inspection device irradiates light onto the item, which is in a fixed position at the predetermined inspection position, and inspects the quality of the item based on the spectral characteristics of the transmitted light that passes through the item upon irradiation with this light (also called irradiated light).

[0016] The items to be inspected are items that are relatively close in size to the area irradiated with light, and include items with an outer diameter φ of several mm to several tens of mm that can be transported individually without packaging, bite-sized items, as well as items and molded products of a predetermined shape manufactured using existing manufacturing equipment or manufacturing equipment without inspection functions, and especially items that do not change shape during transportation.

[0017] Examples of such articles include pharmaceutical preparations such as tablets, capsules, lozenges, and drops, as well as candy and chocolate. The following description will be given taking as an example an article to be inspected a tablet W that is circular in plan view, has a height (thickness) smaller than its diameter, and is roughly cylindrical in side view. Note that the article to be inspected is not limited to a circular shape in plan view, and articles of various shapes such as an oval shape or a polygonal shape can also be used.

[0018] The conveying unit may be, for example, a conveying unit configured to align and convey articles individually, such as a conveying belt, a conveying disk, or a conveying chute. In this embodiment, an example will be described in which a conveying disk 11 (see FIG. 1) is used as the conveying unit.

[0019] As shown in Fig. 1, the conveying disk 11 is a conveying unit configured to suck tablets W into suction holes on its outer peripheral surface and convey them in the circumferential direction while rotating horizontally. In the conveying disk 11, the tablets W are conveyed with their upper and lower surfaces kept horizontal as their sides are sucked into the suction holes. In Fig. 1, only a portion of the outer peripheral side of the conveying disk 11 is shown.

[0020] The article inspection device 10 according to this embodiment includes a spectroscopic measurement device 1 and an inspection unit 2.

[0021] [Spectrometer] The spectroscopic measurement device 1 includes a light source unit 3, a light detection unit 4, and a reflective cover 5. The spectroscopic measurement device 1 irradiates a tablet W to be measured with broadband light (visible light, near-infrared to terahertz light (terahertz waves)), and measures the spectral characteristics of the light that passes through the tablet W in response to the irradiation of this light.

[0022] (Light source part) The light source unit 3 is configured to irradiate broadband light onto the tablet W passing through a predetermined inspection position, i.e., onto the tablet W being conveyed (moving). In this embodiment, the light source unit 3 is arranged on the opposite side (lower side in this embodiment) from the light detection unit 4 across the conveyance path of the tablet W so as to irradiate light from one side (lower side in this embodiment) of a pair of circular end faces of the approximately cylindrical tablet W to the other side (upper side in this embodiment).

[0023] The conveying path of the tablet W is an area through which the tablet W passes during conveyance. The predetermined inspection position is a position on the conveying path of the tablet W where the light source unit 3 and the light detection unit 4 are arranged.

[0024] The light source unit 3 includes a light source 30 , a light guide 31 , and an optical member 32 .

[0025] The light source 30 is composed of a broadband light source, such as a halogen lamp, in order to irradiate broadband light onto the tablet W to be measured, and is provided at a predetermined position as a light source unit integrally assembled with a lamp holding means (not shown) and a case having heat dissipation fins, and is connected to a power supply unit (neither of which is shown).

[0026] Broadband light refers to visible light and near-infrared to terahertz light (light including terahertz waves). The wavelength of the irradiated light does not need to cover all of these; for example, a wavelength band of 400-2500 nm can easily penetrate a measured object such as a tablet and is less likely to be damaged by ultraviolet light, so it may be limited to this wavelength band or the near-infrared band within this wavelength band. Furthermore, if the absorption spectrum of the component to be measured is known, only the wavelength band corresponding to the absorption spectrum may be used.

[0027] The light guide 31 is configured by bundling a large number of optical fibers, for example, and guides the light from the light source 30 to an optical member 32 that condenses the light.

[0028] The optical member 32 is disposed on the tip surface side of the light guide 31, specifically, above the tip surface of the light guide 31. The optical member 32 is a member that focuses light emitted from the tip surface of the light guide 31 onto the tablet W at a predetermined inspection position (the lower surface of the tablet W in the example of FIG. 1).

[0029] The light emitted from the light source 30 is irradiated onto the tablet W via the light guide 31 and the optical member 32 described above.

[0030] (Photodetector) The light detecting section 4 has an optical fiber 41 and a spectroscope 42. The light detecting section 4 is formed as a unit by supporting the optical fiber 41 and the spectroscope 42 on a base member 40.

[0031] The light detection unit 4 is positioned on the opposite side (in this embodiment, the upper side) from the light source unit 3 across the conveying path of the tablet W, so as to face the other (in this embodiment, the upper side) of a pair of circular end faces of the approximately cylindrical tablet W.

[0032] The optical fiber 41 is configured so that transmitted light that has passed through the tablet W at a predetermined inspection position is incident on its core (not shown). The transmitted light that has passed through the tablet W is incident on the optical fiber 41 from an end face (hereinafter referred to as the "incident end face") 41a of the incident surface of the optical fiber 41. The transmitted light that has entered the optical fiber 41 passes through the optical fiber 41 and reaches the spectroscope 42.

[0033] The spectroscope 42 performs spectrometry using, for example, a grating that utilizes differences in the diffraction angle depending on the wavelength of light. Specifically, the light that enters the spectroscope 42 is irradiated onto a grating (diffraction grating) and separated into individual wavelength components. The light separated into individual wavelength components is then detected for each wavelength component by a row of photodetector elements. The light intensity for each wavelength component is then measured. The grating is an optical element with multiple grooves engraved on its surface.

[0034] A tapered optical fiber having a large input diameter and a small output diameter can be used as the optical fiber 41. This allows the transmitted light to be incident on the spectroscope 42 more efficiently.

[0035] In this way, the light detection unit 4 receives the transmitted light irradiated from the light source unit 3 and transmitted through the tablet W using the optical fiber 41, and measures the spectral characteristics of the transmitted light received by the optical fiber 41 using the spectroscope 42.

[0036] (reflective cover) The reflective cover 5 is arranged with a predetermined gap G between it and the surface S (the upper surface in this embodiment) of the tablet W that faces the incident end surface 41a of the optical fiber 41.

[0037] The reflective cover 5 has an end 51 on the spectroscope 42 side (upper side in this embodiment) and an end 52 on the tablet W side (lower side in this embodiment), and is held in the arrangement described above by attaching the end 51 to the base member 40. Note that the reflective cover 5 is not limited to being held by the base member 40, and may be configured to be held by, for example, a bracket not shown. As a method for holding the reflective cover 5, various known holding methods can be adopted.

[0038] The reflective cover 5 may be configured to be detachably attached to the base member 40. In this case, it can be replaced with a reflective cover having a reflective surface of a different size, as described below, depending on the size and type of the object to be measured.

[0039] The reflective cover 5 has a reflective surface 53 that reflects light transmitted through the tablet W onto the surface S of the tablet W. The reflective surface 53 is formed on the end 52 side on the tablet W side, and is configured by a curved surface having a spherical crown shape that is less than a hemisphere and that spreads from the incident end surface 41a of the optical fiber 41 toward the tablet W. In other words, the reflective surface 53 is formed on the end 52 of the reflective cover 5 by a concave spherical surface that is recessed into a spherical crown shape that is less than a hemisphere on the end 51 side.

[0040] The spherical crown shape refers to the shape of the side of each solid (called a "spherical indentation") after cutting a sphere along a plane, i.e., the shape of the original spherical surface (called a "spherical crown"). Here, the "spherical crown shape less than a hemisphere" refers to the shape of the spherical crown of the smaller indentation of two spherical indentations after cutting a sphere along a plane that does not pass through the center.

[0041] The reflecting surface 53 is made of a smooth mirror surface, and is designed to specularly reflect light incident from the tablet W side.

[0042] In this embodiment, a circular opening 53a is formed at the vertex of the reflecting surface 53, and a hollow transmission line 54 with a circular cross section is formed between the opening 53a and the incident end face 41a of the optical fiber 41. The diameters of the opening 53a and the transmission line 54 are preferably equal to or larger than the diameter d of the incident end face 41a of the optical fiber 41. In addition, the inner peripheral surface of the transmission line 54 is preferably formed by a reflecting surface.

[0043] It is not necessary to form the transmission line 54. In this case, the incident end face 41a of the optical fiber 41 is positioned at the opening 53a formed at the vertex of the reflecting surface 53.

[0044] As shown in FIG. 2, the reflective cover 5 is disposed so that the center point O, which is the same distance from the reflective surface 53, is located on the surface S of the tablet W.

[0045] The center point O is the center of a sphere that has the reflecting surface 53 as its spherical crown. Therefore, the distance from the reflecting surface 53 to the center point O is equal to the radius of the sphere that has the reflecting surface 53 as its spherical crown. Therefore, the distance from any position on the reflecting surface 53 to the center point O is the same.

[0046] When the center point O of the reflecting surface 53 is located on the surface S of the tablet W, for example, as shown by the dotted arrow in Figure 2, light diffusely reflected from the surface S of the tablet W is likely to be specularly reflected by the reflecting surface 53 and collected near the center point O. The light specularly reflected by the reflecting surface 53 and incident near the center point O is likely to be reflected again by the surface S of the tablet W and head toward the incident end surface 41a of the optical fiber 41.

[0047] Here, the distance R from the center point O to the reflecting surface 53, the radius r of the periphery of the reflecting surface 53, the dimension g of the predetermined gap G, and the height h of the reflecting surface 53 will be explained.

[0048] The distance R is equal to the radius of a sphere having the reflective surface 53 as a spherical crown. The radius r is smaller than the distance R because the reflective surface 53 has a spherical crown shape that is less than a hemisphere. The dimension g is set to an optimum value experimentally determined in advance, and specifically, is set to a dimension such that the position of the tablet W during transport does not shift in a direction toward or away from the reflective cover 5 (in the vertical direction in this embodiment), or the tablet W does not lose its posture during transport, causing the tablet W to come into contact with the reflective cover 5. Therefore, the dimension g is not determined depending on the dimension of the reflective surface 53.

[0049] In this embodiment, with the dimension g set as described above, the height h and radius r of the reflecting surface 53 are set so that the center point O of the reflecting surface 53 is located on the surface S of the tablet W, as described above. For example, when the dimension g and the distance R are initially determined, the height h is set so that the relationship R = g + h holds.

[0050] [Inspection Department] The inspection unit 2 has a signal processing unit 2a that processes the spectroscopic characteristics obtained by the light detection unit 4 within a predetermined exposure time, and inspects the quality of the tablet W, i.e., determines whether the quality of the tablet W is good or bad, based on the results of the signal processing.

[0051] The signal processing unit 2a calculates the spectral characteristics of the absorbance absorbed by the tablet W from the spectral characteristics obtained by the light detection unit 4. Specifically, the absorbance A at wavelength λ is obtained by the formula A=-log10(I / Ii), which is the common logarithm of the ratio (transmittance) of the light intensity Ii of the incident light to the light intensity I of the transmitted light, and the transmitted amount detected when there is no tablet W at the predetermined inspection position can be calculated as the light intensity Ii of the incident light.

[0052] The inspection unit 2 compares the spectroscopic characteristics of absorbance of a non-defective tablet W obtained in advance (intensity of each wavelength of the spectrum (including when differentiated multiple times), waveform shape, information obtained by extracting the entire or partial region and creating a calibration curve, statistical information) with the spectroscopic characteristics of absorbance of the tablet W to be inspected that has been transported to a predetermined inspection position, and judges whether the quality of the tablet W is good or bad based on the magnitude of the difference. The inspection unit 2 outputs a sorting signal based on the pass / fail result of the judgment to a sorting unit (not shown) that sorts the tablets W into normal and defective products.

[0053] Specifically, for example, the quality of the tablet W is judged based on whether the difference amount for each wavelength determined by calculation using a calibration curve obtained by statistical calculation results (such as standard deviation) or statistical methods such as regression is within a predetermined range (a range determined based on the results of statistical calculations or the results of the calibration curve).The quality of the tablet W can also be judged based on whether the sum of the intensities of each wavelength is within a predetermined range.Furthermore, if the components of the tablet W are uniform, the quality of the tablet W may be judged based on whether there is an intensity exceeding a predetermined threshold value set in advance in a region other than the specific wavelength.

[0054] [About the function of the reflective cover] Next, referring to Figure 3, the change in the amount of light received by the light detection unit 4 of this embodiment depending on the distance g between the surface S of the tablet W and the reflective cover 5, i.e., the dimension g of the specified gap G, will be explained in comparison with the change in the amount of light received by the light detection unit of a spectroscopic measuring device according to a comparative example that uses a hemispherical reflective cover.

[0055] The hemispherical reflective cover in the comparative example is a reflective cover configured with a curved surface in the shape of a spherical crown when a sphere is cut along a plane passing through the center point of the sphere.

[0056] In addition, in FIG. 3, distance g1 is the dimension g of the gap G, which is set to an optimum value obtained in advance through experiments.

[0057] As shown in Figure 3, both this embodiment and the comparative example have a tendency for the amount of received light to increase as the distance g decreases. Here, in this embodiment, when the distance g is equal to or less than a predetermined distance g2, the amount of received light increases more significantly as the distance g decreases compared to the comparative example. At a distance g1, the ratio between the amount of received light in the comparative example and this embodiment is greatest. In other words, at the distance g1, the effect of the reflective cover 5 of this embodiment on the amount of received light in the light detection unit is greatest compared to the reflective cover of the comparative example.

[0058] However, when the distance g is reduced to the vicinity of "0" (including 0), the amount of received light in the comparative example exceeds the amount of received light in this embodiment. Therefore, the reflective cover 5 of this embodiment is likely to exhibit the effect of increasing the amount of received light when a predetermined gap G is interposed between it and the tablet W.

[0059] [Action and effect] As described above, the spectroscopic measurement device of this embodiment is equipped with a reflective cover 5 having a reflective surface 53 that reflects light that has passed through the tablet W onto the surface S of the tablet W, and the reflective surface 53 of the reflective cover 5 is configured as a curved surface having a spherical crown shape that is less than a hemisphere and extends from the incident end surface 41a toward the tablet W. Therefore, even if there is a gap G between the surface S of the tablet W and the reflective cover 5, the amount of light incident on the incident end surface 41a of the optical fiber 41 can be increased, and the amount of light received by the light detection unit 4 can be increased.

[0060] This makes it possible to improve the signal level in the photodetector 4 and relatively reduce the noise level in the signal input from the photodetector 4 to the signal processor 2a. This reduces the effect of noise on the signal input to the signal processor 2a. This enables highly reproducible measurements and measurements in a short time.

[0061] Furthermore, in the spectroscopic measuring device of this embodiment, the reflective cover 5 is positioned so that the center point O, which is the same distance from the reflective surface 53 of the reflective cover 5, is located on the surface S of the tablet W, thereby further increasing the amount of light incident on the incident end surface 41a of the optical fiber 41.

[0062] Furthermore, the article inspection device 10 according to this embodiment can increase the amount of light received by the light detection unit 4 of the spectroscopic measurement device 1, thereby improving the signal level input to the inspection unit 2 and improving the accuracy of inspection in the inspection unit 2. Furthermore, the improved signal level enables the article inspection device 10 according to this embodiment to perform measurements in a short time, thereby improving the inspection processing capacity.

[0063] [Variations] In this embodiment, a configuration in which the light source unit 3 has a light guide 31 has been described, but the light source unit 3 may also be configured without a light guide 31, i.e., the light source unit 3 may be configured to consist of a light source 30 and an optical member 32.

[0064] Furthermore, in this embodiment, a configuration has been described in which the reflective cover 5 is arranged so that the center point O of the reflective surface 53 is located on the surface S of the tablet W, but this is not limiting, and the center point O of the reflective surface 53 may be offset within a predetermined range toward the light source unit 3 or the light detection unit 4 with respect to the surface S of the tablet W. For example, as shown in FIG. 3, the reflective cover 5 may be arranged so that the center point O is offset from the surface S to the light source unit 3 or the light detection unit 4 within a range where the amount of received light is increased compared to the comparative example, specifically, within a range from a distance g near 0 to a distance g2 where the magnitude of the amount of received light in the comparative example and the amount of received light in this embodiment are interchangeable.

[0065] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0066] 1 Spectrometer 2. Inspection Department 2a Signal processing section 3 Light source section 4. Light detection unit 5 Reflective cover 10. Item inspection equipment 11 Transfer disk 30 light source 31 Light Guide 32 Optical Components 40 Base member 41 Optical Fiber 41a Incidence end face 42 Spectrometer 51, 52 End 53 Reflective surface 53a aperture 54 Transmission Line W Tablet (item) S surface G Gap O center point

Claims

1. a light source unit (3) that irradiates light onto an article (W) being conveyed; a light detection unit (4) in which transmitted light irradiated from the light source unit and transmitted through the object is incident on an optical fiber (41), and the spectral characteristics of the transmitted light that has passed through the optical fiber are measured by a spectroscope (42); a reflective cover (5) disposed between the incident end face (41 a) of the optical fiber and a surface (S) of the article facing the incident end face (41 a) and having a reflective surface (53) that reflects light transmitted through the article to the surface of the article, The reflective cover is a spectroscopic measurement device, wherein the reflective surface is configured as a curved surface having a spherical crown shape that is less than a hemisphere and that spreads from the incident end surface toward the object.

2. The spectroscopic measurement device according to claim 1 , wherein the reflective cover is disposed so that a center point (O) at a constant distance from the reflective surface is located on the surface of the object.

3. A spectroscopic measurement device (1) according to claim 1 or claim 2; and an inspection unit (2) that inspects the quality of the article based on the spectroscopic characteristics measured by the spectrometer.

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