41 from an end surface (hereinafter, referred to as an “incidence end”) 41a of an incidence surface of the optical fiber 41. The transmission light incident on the optical fiber 41 passes through the optical fiber 41 and reaches the spectroscope 42.

The spectroscope 42 performs, for example, spectral separation through a grating using a difference in a diffraction angle depending on the wavelength of light. Specifically, the light entering the spectroscope 42 is emitted to the grating (diffraction grating) and is spectrally separated into wavelength components. Then, the light spectrally separated into the wavelength components is detected by light detection elements arranged in one row for each wavelength component. Then, light intensity for each wavelength component is measured. The grating is an optical element in which a plurality of grooves are engraved on a surface.

As the optical fiber 41, a tapered optical fiber having a shape in which a diameter of an input is large and a diameter of an output is small can be used. As a result, the transmission light can be more efficiently incident on the spectroscope 42.

As described above, the light detection unit 4 measures the spectral characteristic of the transmitted light that is emitted from the light source unit 3 and transmitted through the tablet W using the spectroscope 42, the transmission light being incident on the optical fiber 41 and passing through the optical fiber 41.

In the present embodiment, the light detection unit 4 is provided with a reflection cover 43. The reflection cover 43 is provided to surround the incidence end 41a of the optical fiber 41, and has a hemispherical shape that spreads from the incidence end 41a of the optical fiber 41 toward the upper surface of the tablet W. The shape of the inner surface of the reflection cover 43 is not limited to the hemispherical shape and may be, for example, a frustum shape.

The reflection cover 43 has a reflection surface 43a that reflects the transmission light transmitted through the tablet W to the upper surface of the tablet W on the inner surface of the hemisphere. In addition, an incidence end 41a of the optical fiber 41 is disposed near the apex of the hemisphere.

The transmission light that is emitted from the light source unit 3 and transmitted through the tablet W is repeatedly reflected between the reflection surface 43a of the reflection cover 43 and the upper surface of the tablet W, so that a part of the light that cannot reach the incidence end 41a of the optical fiber 41 in a case where the reflection cover 43 is not provided also reaches the incidence end 41a. As described above, the reflection cover 43 can increase an amount of transmission light incident on the incidence end 41a of the optical fiber 41.

In the present embodiment, the light detection unit 4 has a tubular member 45 between the tablet W and the optical fiber 41 at the predetermined inspection position. The tubular member 45 is attachably and detachably attached to the base member 40, protrudes from the base member 40 toward a tablet W side, and is open on the tablet W side. The tubular member 45 may be made of, for example, metal such as aluminum or a resin.

Specifically, the tubular member 45 is formed in a tubular shape having a predetermined length in a protruding direction (in the present embodiment, a vertical direction), and has an opening end 45b in which an opening 45a is formed at an end portion on the tablet W side (in the present embodiment, the lower side) in the protruding direction. In the present embodiment, a shape of the opening 45a is formed in a perfect circular shape.

An end portion of the tubular member 45 on a side opposite to the tablet W side (the upper side in the present embodiment) in the protruding direction is also open, but a diameter of the opening need not be the same as a diameter of the opening 45a. An opening having a size through which at least the optical fiber 41 passes need only be formed at the end portion of the tubular member 45 on the side opposite to the tablet W side in the protruding direction.

The tubular member 45 is disposed such that the incidence end 41a of the optical fiber 41 and the opening 45a overlap each other in an axial direction of the tubular member 45 (in the vertical direction in FIG. 1). In other words, this means that, when the light detection unit 4 is viewed from the tablet W side in the axial direction of the tubular member 45, the incidence end 41a of the optical fiber 41 is accommodated in an opening region of the opening 45a. It is preferable that the center of the incidence end 41a of the optical fiber 41 is positioned on an axis of the tubular member 45 passing through the center of the opening 45a in these dispositions. The transmission light transmitted through the tablet W passes through the tubular member 45 from the opening 45a and is incident on the optical fiber 41.

In addition, the opening 45a of the tubular member 45 is positioned on the tablet W side with respect to the incidence end 41a of the optical fiber 41. In other words, the incidence end 41a of the optical fiber 41 is spaced from the tablet W in the axial direction of the tubular member 45 with respect to the opening 45a of the tubular member 45. In the present embodiment, the incidence end 41a of the optical fiber 41 is disposed to be positioned inside the tubular member 45.

The incidence end 41a of the optical fiber 41 may be disposed, for example, to be positioned inside the base member 40. Further, the optical fiber 41 may be configured such that a position of the incidence end 41a in the axial direction of the tubular member 45 is adjustable.

An inner wall surface 45c of the tubular member 45 is subjected to a low-reflective surface treatment for absorbing light. For example, the inner wall surface 45c is made black coating to reduce the reflection of light.

In the present embodiment, the opening end 45b of the tubular member 45 is sharply formed. That is, the tubular member 45 has a narrowing shape at the opening end 45b, and an area of a facing surface facing the tablet W at the opening end 45b is reduced.

In addition, the tubular member 45 is formed in a tapered shape in which a diameter of an outer wall surface 45d thereof increases from the opening end 45b toward a base member 40 side. Accordingly, rigidity of the tubular member 45 in a case where the tubular member 45 is attached to the base member 40 is increased. The outer wall surface 45d of the tubular member 45 need not have a tapered shape. The outer wall surface 45d may be subjected to a low-reflective surface treatment for absorbing light.

The narrowing shape of the opening end 45b may be, for example, a shape that gradually narrows according to the tapered shape of the outer wall surface 45d, or a shape in which only the shape of the end portion of the tubular member 45 on an opening end 45b side narrows.

Inspection Unit

The inspection unit 2 has a signal processing unit 2a that performs signal processing on the spectral characteristic obtained by the light detection unit 4 within a predetermined exposure time, and inspects a quality of the tablet W, that is, performs good/bad determination of the quality of the tablet W from a result of the signal processing.

The signal processing unit 2a calculates a spectral characteristic in an absorbance of the tablet W from the spectral characteristic obtained by the light detection unit 4. Specifically, an absorbance A at a wavelength A is obtained by an equation A=−log10(I/Ii) of a common logarithm of a ratio of light intensity Ii of incident light to light intensity I of the transmission light (transmittance), and a transmission amount detected in a state where the tablet W is not present at the predetermined inspection position can be obtained as the light intensity Ii of the incident light.

The inspection unit 2 compares a spectral characteristic (intensity of each wavelength of the spectrum (including a case of being differentiated multiple times), a shape of a waveform, information obtained by extracting the entire or a part of a region and providing a calibration curve thereof, and statistical information) in an absorbance of a good product of the tablet W acquired in advance with the spectral characteristic in the absorbance of the tablet W to be inspected, which is transported to the predetermined inspection position, and determines whether or not the quality of the tablet W is good based on the magnitude of a difference thereof. The inspection unit 2 outputs a selection signal based on a good/bad result of the determination to a selection unit (not shown) that selects the tablet W as a normal product or a defective product.

Specifically, whether or not the quality of the tablet W is good is determined, for example, based on whether or not a differential amount for each wavelength defined by calculation using a calibration curve obtained by a statistical calculation result (such as standard deviation), a statistical method such as regression, or the like is within a predetermined range (a range defined based on a statistical calculation result or a result of calibration curve). In addition, it is also possible to determine whether or not the quality of the tablet W is good based on whether or not total intensity of wavelengths is within a predetermined range. Further, in a case where the components of the tablet W are uniform, whether or not the quality of the tablet W is good may be determined based on whether or not there is intensity exceeding a predetermined threshold value set in advance in a region other than a specific wavelength.

Regarding Action of Tubular Member

Next, an action of the tubular member 45 of the present embodiment will be described with reference to FIGS. 2 and 3.

FIGS. 2 and 3 schematically show a state in which a plurality of tablets W are sequentially transported in a transport direction at predetermined intervals and are irradiated with light from the light source unit 3 at the predetermined inspection position. Solid-line arrows and broken-line arrows in FIGS. 2 and 3 schematically show an optical path of a part of the light emitted from the light source unit 3 or the reflected light.

FIG. 2 shows a spectroscopic measurement device 101 of a comparative example that does not including the tubular member 45. The spectroscopic measurement device 101 of the comparative example is different from the spectroscopic measurement device 1 of the present embodiment in that the tubular member 45 is not provided, but the other configurations are the same as those of the spectroscopic measurement device 1 of the present embodiment. FIG. 3 shows the spectroscopic measurement device 1 of the present embodiment.

As shown in FIG. 2, in the spectroscopic measurement device 101 of the comparative example, most of the light emitted from the light source unit 3 is incident on the tablet W, while the light is reflected from side surfaces or the like of the tablets W (a previously transported tablet and a tablet to be transported next) arranged at predetermined intervals with respect to the tablet W being measured and is incident on the reflection cover 43. The light incident on the reflection cover 43 is further reflected in the reflection cover 43 or reflected on the upper surface of the tablet W and is incident on the incidence end 41a of the optical fiber 41.

As described above, the light reflected by the tablets W transported before and after the tablet W being measured and incident on the incidence end 41a of the optical fiber 41 is incident on the optical fiber 41 as stray light. In this case, there is a concern that accuracy of data of the spectrum of the light received by the light detection unit 4 may be decreased.

On the other hand, as shown in FIG. 3, in the spectroscopic measurement device 1 of the present embodiment, most of the light emitted from the light source unit 3 is incident on the tablet W, while the light is reflected from the side surfaces or the like of the tablets W (the previously transported tablet and the tablet to be subsequently transported) arranged at the predetermined intervals with respect to the tablet W being measured, but the reflected light is blocked by the outer wall surface 45d of the tubular member 45, and the amount of the light incident on the reflection cover 43 is reduced.

In addition, a part of the light reflected from the side surfaces or the like of the tablets W arranged at predetermined intervals with respect to the tablet W being measured is also reflected from a lower surface of the base member 40. Here, in a case where the lower surface of the base member 40 is close to the opening end 45b of the tubular member 45, there is a possibility that the light reflected by the lower surface of the base member 40 is reflected again on at least any of the upper surfaces of the previously transported tablet W and the tablet W to be subsequently transported and is incident on the tubular member 45.

In the present embodiment, since the lower surface of the base member 40 is spaced further from the tablet W as compared with the opening end 45b of the tubular member 45, the optical path of the light reflected by the lower surface of the base member 40 is lengthened, and the light is attenuated before being incident on the tubular member 45 after being reflected again on at least any of the upper surfaces of the tablet W previously transported and the tablet W to be subsequently transported. Therefore, it is possible to reduce the possibility that the light reflected by the lower surface of the base member 40 is incident on the tubular member 45.