Optical measurement device

Abstract

This optical measurement device (1) is provided with a light source device (35) that emits wavelength-swept light, a conveyance device (10) that conveys a measurement object M, an irradiation device (40) that that guides the wavelength-swept light from the light source device (35) to a measurement position P on the conveyance path of the conveyance device (10) and has an optical path switching unit (42) that switches the optical path, a measurement light-receiving device (51) that receives the wavelength-swept light emitted to the measurement position P, an object detection sensor (55) that detects the conveyed measurement object M, a conveyance detection sensor that detects the conveyance speed or the displacement in the conveyance direction of the measurement object M, and a control device (65). The control device (65) estimates the timing at which the measurement object M reaches the measurement position P on the basis of the detection by the object detection sensor (55) and the conveyance speed or the displacement in the conveyance direction detected by the conveyance detection sensor, and controls the optical path switching unit (42) at this timing to configure the optical path so that the light reception device receives the wavelength-swept light while the measurement object M is present at the measurement position P.

Description

Light Measuring Device

[0001] The present invention relates to an optical measurement device.

[0002] One conventional measurement technique that utilizes optical characteristics is spectroscopy using a wavelength-swept spectrometer. This spectrometer generates wavelength-swept light whose wavelength changes over time and irradiates the object to be measured with the generated wavelength-swept light. The wavelength-swept light is a pulse or pulse train in which time and wavelength have a one-to-one relationship. The time waveform of the light obtained by irradiating the object to be tested with this wavelength-swept light is detected by a photodetector, and the signal waveform output from the photodetector represents a spectrum in which the time axis corresponds to the wavelength.

[0003] Spectroscopic analysis is classified into transmission type, in which the light transmitted through the object is the object light, and reflection type, in which the reflected light is the object light. Reflection type is suitable for measuring objects with high reflectivity, but the optical information obtained is limited to that near the object's surface. Therefore, it cannot be said to have sufficient accuracy for measuring precision industrial products, specimens collected from plants and animals, substances ingested by humans, liquids and gases produced in production plants, etc.

[0004] On the other hand, transmission types can obtain optical characteristics not only from the surface of an object but also from deeper parts, making them suitable for measuring foods and beverages (hereinafter collectively referred to as "food and beverages"). Patent Document 1 listed below discloses a transmission type product inspection device. This product inspection device includes an irradiation optical system that irradiates the surface of the product (object to be inspected) with pulsed light, and a photodetector that is provided on the back side of the product and receives the light that has passed through the product.

[0005] 10 shows an example of a wavelength sweep type spectroscopic device 100. This spectroscopic device 100 includes a light source device 110, a spectroscopic head 120, and a processing unit .

[0006] The light source device 110 generates wavelength-swept light L1, which is guided to the spectroscopic head 120. The irradiation optical system 121 of the spectroscopic head 120 irradiates the wavelength-swept light L1 onto a sample T, and transmitted light (object light) L2 that passes through the sample T is received (detected) by a first light receiver 122. In addition, the irradiation optical system 121 branches a portion of the wavelength-swept light L1 as reference light L3, and the branched reference light L3 is received (detected) by a second light receiver 123.

[0007] The first detection signal S1 output from the first photodetector 122 and the second detection signal S2 output from the second photodetector 123 are each transmitted to the arithmetic processing device 130. The object light L2 and the reference light L3 each inherit the one-to-one time-wavelength correspondence of the wavelength-swept light L1. Therefore, the time waveform of the first detection signal S1 can be converted into the spectrum of the object light L2 by converting the time axis into wavelength. Similarly, the time waveform of the second detection signal S2 can be converted into the spectrum of the reference light L3 by converting the time axis into wavelength. The arithmetic processing device 130 measures (calculates) the spectral characteristics (reflectance) of the sample T by calculating the ratio of each corresponding wavelength of the object light L2 to the reference light L3.

[0008] Japanese Patent Application Laid-Open No. 2020-159973

[0009] In the conventional transmission-type spectrometers described above, when the product to be measured (hereinafter also referred to as the product) has low light transmittance and high diffusion properties, the receiver is designed and selected assuming low-power incident light, while a high-peak-power pulsed laser is used as the light source device to increase the power of the transmitted light.

[0010] Furthermore, when inspecting industrially mass-produced products, the products are generally transported at high speed by a transport device. Therefore, if the stability of the product deteriorates during transport, the product may fall off the transport device or become misaligned, resulting in a situation where the product is not present at the measurement position where it should be. If this occurs, the wavelength-swept light L1, which is a pulsed laser beam irradiated at the measurement position, will directly enter the photodetector without passing through the product.

[0011] Furthermore, depending on the manner in which the products are transported, there may be gaps between successively transported products, and in such cases, there is also a risk that the laser beam will be directly incident on the receiver through the gaps.

[0012] Thus, as described above, when a photoreceiver is designed and selected assuming low-power incident light, if a high-peak power laser beam is incident directly on the photoreceiver, and the power of the laser beam exceeds the allowable power of the photoreceiver, there is a risk that the reliability of the photoreceiver will be impaired (degraded) by the power of the incident laser beam.

[0013] In particular, elements that have an amplification mechanism within them, such as avalanche photodiodes, are known to have a low damage threshold. For example, the damage threshold of the InGaAs avalanche photodetector APD430C manufactured by THORLABS, USA, is 1 mW. However, the power of the laser beam used in this spectroscopic method is much greater than this, so if the laser beam is incident directly onto the element, the element will be damaged.

[0014] The present invention has been made in view of the above circumstances, and has as its object to provide an optical measurement device that can prevent a laser beam from being directly incident on a photodetector during measurement.

[0015] In order to solve the above problems, the present invention provides a measurement apparatus comprising: a light source device that generates wavelength swept light; a conveying device having two endless annular conveying belts that are arranged opposite each other and form a linear conveying path, and a drive unit that rotates the conveying belts, and that conveys a measurement object along the conveying path while straddling the two conveying belts; an irradiation device that has an optical path that guides and irradiates the wavelength swept light generated by the light source device to a measurement position set on the conveying path, and that is arranged on the optical path and has an optical path switching unit that switches the optical path of the wavelength swept light; a light receiving device that receives the wavelength swept light irradiated to the measurement position by the irradiation device; an object detection sensor that is arranged upstream of the measurement position in the conveying direction of the conveying device and that detects the measurement object being conveyed by the conveying device; a conveying detection sensor that detects a displacement of the conveying speed or conveying direction of the conveying belts; and a control device that controls the drive unit of the conveying device and the optical path switching unit of the irradiation device, The control device estimates the timing when the object to be measured will reach the measurement position based on detection by the object detection sensor and the displacement of the conveying speed or conveying direction detected by the conveying detection sensor, and controls the optical path switching unit in synchronization with the estimated timing to change the optical path so that, while the object to be measured is present at the measurement position, the wavelength swept light is received by the light receiving device, and only while the object to be measured is not present at the measurement position, the wavelength swept light is not received by the light receiving device.

[0016] According to the optical measurement device of this aspect (first aspect), the measurement object is transported along the transport path while straddling two transport belts of the transport device, while the light source device generates wavelength swept light, the generated wavelength swept light is guided by the irradiation device to a measurement position set on the transport path, and the wavelength swept light irradiated at this measurement position is received by the light receiving device.

[0017] The measurement object transported by the transport device is detected by an object detection sensor provided upstream of the measurement position, and the control device estimates the timing when the measurement object will reach the measurement position based on the detection of the measurement object by the object detection sensor and the displacement of the transport speed or transport direction of the transport belt detected by the transport detection sensor, and controls the optical path switching unit of the irradiation device in synchronization with the estimated timing, so that the optical path is switched so that the wavelength swept light is received by the light receiving device while the measurement object is present at the measurement position, and the wavelength swept light is not received by the light receiving device while the measurement object is not present at the measurement position. Then, while the measurement object is present at the measurement position, the wavelength swept light passes through the measurement object and is received by the light receiving device, and a detection signal corresponding to the optical characteristics of the measurement object is output by the light receiving device.

[0018] Thus, according to this optical measurement device, while the object to be measured is not present at the measurement position, the optical path switching unit switches the optical path of the wavelength swept light to an optical path that is not received by the light receiving device, thereby preventing the wavelength swept light from being received directly by the light receiving device and avoiding damage to the light receiving device that would occur if the wavelength swept light were received directly by the light receiving device.

[0019] In the first aspect, the optical path switching unit may include any one of a galvanometer mirror, a MEMS (Micro Electro Mechanical Systems) mirror, a piezo-driven mirror, and a polygon mirror.

[0020] In the first aspect, the irradiation device may further include an aperture on the exit side of the optical path switching section.

[0021] The present invention also provides a measuring device comprising: a light source device that generates wavelength swept light; a conveying device having two endless annular conveying belts that are arranged opposite to each other and form a linear conveying path, and a drive unit that rotates the conveying belts, and that conveys a measurement object along the conveying path while straddling the two conveying belts; an irradiation device having an optical path that guides and irradiates the wavelength swept light generated by the light source device to a measurement position set on the conveying path, and having a light blocking unit that is arranged on the optical path and switches between transmitting and blocking the wavelength swept light; a light receiving device that receives the wavelength swept light irradiated to the measurement position by the irradiation device; an object detection sensor that is arranged upstream of the measurement position in the conveying direction of the conveying device and that detects the measurement object being conveyed by the conveying device; a conveying detection sensor that detects the conveying speed or displacement in the conveying direction of the conveying belts; and a control device that controls the drive unit of the conveying device and the light blocking unit of the irradiation device, The control device relates to an optical measurement device configured to estimate the timing when the object to be measured will reach the measurement position based on detection by the object detection sensor and the displacement of the conveying speed or conveying direction detected by the conveying detection sensor, and to control the shading part in synchronization with the estimated timing to make the shading part transparent while the object to be measured is present at the measurement position, and to make the shading part opaque while the object to be measured is not present at the measurement position.

[0022] According to the optical measurement device of this aspect (second aspect), the measurement object is transported along the transport path while straddling two transport belts of the transport device. Meanwhile, wavelength swept light is generated by the light source device, and the generated wavelength swept light is guided by the irradiation device to a measurement position set on the transport path. The wavelength swept light irradiated at this measurement position is received by the light receiving device.

[0023] The measurement object transported by the conveying device is detected by an object detection sensor provided upstream of the measurement position. Based on the detection of the measurement object by the object detection sensor and the displacement of the conveying belt's conveying speed or conveying direction detected by the conveying detection sensor, the control device estimates the timing at which the measurement object will reach the measurement position. The light-shielding unit of the irradiation device is controlled in synchronization with the estimated timing to transmit the wavelength-swept light while the measurement object is present at the measurement position and to block the wavelength-swept light while the measurement object is not present at the measurement position. The wavelength-swept light is transmitted through the measurement object and received by the light-receiving device only while the measurement object is present at the measurement position, and a detection signal corresponding to the optical characteristics of the measurement object is output by the light-receiving device. The non-transmitting state includes not only a state in which light transmission is completely blocked, but also a state in which the transmitted light is dimmed.

[0024] Thus, with this optical measurement device, while the object to be measured is not present at the measurement position, the light path of the wavelength swept light is blocked by the light-shielding section, thereby preventing the wavelength swept light from being received directly by the light-receiving device, and preventing damage to the light-receiving device that would occur if the wavelength swept light were received directly by the light-receiving device.

[0025] In the second aspect, the light-shielding portion may include either a movable shutter or a variable attenuator, and the variable attenuator may include either a liquid crystal shutter, an acousto-optical modulator, or an electro-optical modulator.

[0026] In each of the above aspects, the wavelength swept light may be configured to pass between the two conveyor belts and be irradiated onto the measurement object.

[0027] According to the optical measurement device of the present invention, while the object to be measured is not present at the measurement position, the optical path can be controlled so that the wavelength swept light is not received by the light receiving device, thereby preventing the wavelength swept light from being received directly by the light receiving device and avoiding damage to the light receiving device that would occur if the wavelength swept light were received directly by the light receiving device.

[0028] FIG. 1 is a front view showing a schematic configuration of a light measurement device according to one embodiment of the present invention. FIG. 2 is a plan view showing a transport device and the like according to this embodiment. FIG. 3 is a cross-sectional view taken along the direction of arrows A-A in FIG. 2. FIG. 4 is a cross-sectional view taken along the direction of arrows C-C in FIG. 3. FIG. 4 is a cross-sectional view taken along the direction of arrows B-B in FIG. 2. FIG. 5 is an explanatory diagram showing a schematic configuration of a light measurement device according to this embodiment, and is an explanatory diagram for explaining optical paths in a light source device and an irradiation device. FIG. 6 is an explanatory diagram for explaining wavelength swept light. FIG. 7 is an explanatory diagram for explaining spectroscopy by the light measurement device of this embodiment. FIG. 8 is an explanatory diagram showing a schematic configuration of a light measurement device according to another embodiment of the present invention. FIG. 9 is a block diagram showing a conventional light measurement device.

[0029] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0030] As shown in Figures 1 to 6, the optical measurement device 1 of this example is composed of a supply unit 2, a conveying device 10, a light source device 35, an irradiation device 40, a reference light receiving device 50, a measurement light receiving device 51, an object detection sensor 55, a sorting device 60, a control device 65, and a calculation device 70. Details of each component are described below. Note that the measurement object M in this example is a tablet having a circular planar shape and an oval longitudinal cross-sectional shape, but examples of the measurement object M include pharmaceuticals (tablets, capsules, etc.) having other shapes, food, mechanical parts, electronic parts, etc. However, the measurement object M is not limited to these.

[0031] The supply unit 2 is a mechanism that aligns the measurement objects M in a line and supplies them to the conveying device 10, and is composed of a hopper 3, a vibrating feeder 4, a chute 5, an alignment table 6, etc. The hopper 3 stores a large number of measurement objects M that are input from an upper opening, and discharges an appropriate amount of measurement objects M from its lower opening. The vibrating feeder 4 is provided below the hopper 3, receives the measurement objects M that are discharged from the lower opening of the hopper 3, and applies vibrations to the measurement objects M, thereby moving the measurement objects M along a set path.

[0032] The chute 5 is connected to the conveying end of the vibrating feeder 4, receives the measurement objects M discharged from the conveying end, slides them diagonally downward, and discharges them from its lower end. The alignment table 6 has a circular rotating table installed horizontally below the lower end of the chute 5, receives the measurement objects M supplied from the chute 5 on the rotating table, and by the rotation of the rotating table, aligns the measurement objects M in a row and supplies them to the conveying device 10.

[0033] As shown in Figures 2 and 3, the conveying device 10 is composed of a suction box 11 in the form of an elongated housing, two endless circular conveying belts 15 and 16 arranged side by side facing each other at a predetermined interval, an exhaust pump 17 that creates a negative pressure inside the suction box 11, and a cover body 24 that is arranged to surround the suction box 11.

[0034] As shown in FIG. 4, the suction box 11 has a slit 12 that opens on its top surface and is formed along its longitudinal direction, and further has guide grooves 13 and 14 that are formed on both sides of the slit 12.

[0035] 3, a drive pulley 18 and driven pulleys 19, 20, and 21 are disposed at the four corners of the cover body 24 so as to surround the suction box 11, and the conveyor belts 15 and 16 are wound around the drive pulley 18 and driven pulleys 19, 20, and 21 while fitting into guide grooves 13 and 14 formed in the upper surface of the suction box 11, respectively. A drive motor 22 is connected to the drive pulley 18, and the drive pulley 18 is driven by the drive motor 22. When the drive pulley 18 rotates in the direction of arrow D, the conveyor belts 15 and 16 rotate in the direction of arrow E. A rotary encoder 23 is attached to the drive motor 22, and the rotational speed of the drive motor 22 is detected by the rotary encoder 23. From the rotational speed of the drive motor 22, the running speed (conveying speed) of the conveyor belts 15 and 16 can be calculated.

[0036] The rotary encoder 23 detects the rotation angle per unit time of the drive motor 22, and in this sense, can detect the running speed (conveying speed) of the conveyor belts 15, 16. The running speed is equivalent to the movement amount (displacement amount) of the conveyor belts 15, 16, and therefore the rotary encoder 23 can be thought of as a means for detecting the movement amount (displacement amount) of the conveyor belts 15, 16. Furthermore, the rotary encoder 23 functions as a conveyance detection sensor that detects the conveyance speed or displacement in the conveyance direction of the conveyor belt, but such a conveyance detection sensor is not limited to the rotary encoder 23.

[0037] In this embodiment, the conveyor belts 15 and 16 are timing belts, and the drive pulley 18 and driven pulleys 19, 20, and 21 are timing pulleys, but the present invention is not limited to such configurations.

[0038] In this conveying device 10, when the exhaust pump 17 evacuates the suction box 11 to create a negative pressure inside the suction box 11, this negative pressure acts between the conveying belts 15, 16 through the slit 12. Then, when the measurement objects M are sequentially supplied from the upstream side of this conveying device 10 so as to straddle the conveying belts 15, 16, the supplied measurement objects M are adsorbed onto the conveying belts 15, 16 by the action of the negative pressure, and the tablets adsorbed onto the conveying belts 15, 16 are conveyed toward their conveying end by the conveying belts 15, 16 traveling in the direction of arrow E. Thus, in this conveying device 10, the upper surfaces of the conveying belts 15, 16 serve as conveying support surfaces, and their traveling paths serve as adsorption conveying paths.

[0039] A housing-shaped cover body 30 is provided on one side of the conveying device 10 (in this example, the front side), and this cover body 30 contains the light source device 35, the main parts of the irradiation device 40, and the reference light receiving device 50.

[0040] A measurement position P is set at an appropriate position on the suction conveyance path formed by the conveyor belts 15 and 16, and a measurement light receiving device 51 is provided above this measurement position P. An object detection sensor 55 is provided above an appropriate position set on the suction conveyance path upstream of the measurement position P, and a sorting device 60 is provided above near the end of the conveyance downstream of the measurement position P.

[0041] The light source device 35 includes a pulsed light source that emits pulsed light and a stretcher that stretches and emits the pulsed light emitted from the pulsed light source. Specifically, the pulsed light source emits broadband pulsed light having a broad, continuous spectrum. The spectrum of the broadband pulsed light is continuous over a wavelength range of at least 10 nm, preferably 50 nm, and more preferably 100 nm, for example, in the range of 900 nm to 1300 nm, and the width of the wavelength range of the broadband pulsed light only needs to cover the wavelength range required for spectroscopy. Furthermore, the stretcher generates and emits wavelength-swept light by stretching the broadband pulsed light emitted from the pulsed light source on the time axis.

[0042] FIG. 7 shows wavelength-swept light, with the upper graph showing the intensity (time waveform) IWS(t) of the wavelength-swept light and the lower graph showing the change in wavelength λ of the wavelength-swept light over time. In this example, the wavelength-swept light is a single pulse of light, with a dominant wavelength λ1 at its leading edge and a dominant wavelength λn at its trailing edge, and the wavelength within the pulse varies over time between λ1 and λn. In this example, the wavelength-swept light is a positively chirped pulse (λ1>λn) whose frequency increases over time, in other words, whose wavelength shortens over time. However, the wavelength-swept light is not limited to this, and may also be a negatively chirped pulse whose wavelength lengthens over time (λ1<λn). Alternatively, the wavelength-swept light may be a pulse train consisting of temporally isolated pulses (wave packets) for each wavelength.

[0043] The irradiation device 40 is a mechanism that guides the wavelength-swept light emitted from the light source device 35 and irradiates it onto a measurement position P set on the conveying path of the conveying device 10. In this example, the irradiation device 40 is composed of a beam splitter 41, a galvanometer mirror 42, a motor 43, a slit member 44, and a first mirror 45 provided in the cover body 30, as well as a second mirror 46 provided in the suction box 11 of the conveying device 10, but may also include other mirrors, lenses, etc.

[0044] The beam splitter 41 is an optical element provided on the optical path of the wavelength swept light emitted from the light source device 35 and splits the wavelength swept light into two beams, one of which is transmitted in the emission direction as it is to become measurement light, and the other is reflected at an angle of, for example, 45° to become reference light. The reference light is incident on a reference beam receiving device 50 provided on the side of the light source device 35.

[0045] The galvanometer mirror 42 is provided on the optical path of the measurement light transmitted through the beam splitter 41 and reflects the measurement light toward a first mirror 45 provided above it. The galvanometer mirror 42 is configured to rotate by a motor 43 about an axis that is horizontally perpendicular to the optical axis of the measurement light, and this rotation adjusts the reflection angle of the measurement light. The galvanometer mirror 42 and the motor 43 constitute an optical path switching unit. Note that, although the galvanometer mirror 42 is used as the optical path switching unit in this example, this is not limited thereto, and a MEMS (Micro Electro Mechanical Systems) mirror, a polygon mirror, a piezo-driven mirror, or the like can be used instead of the galvanometer mirror 42.

[0046] The slit member 44 is a light-blocking member having a slit as an opening, and is provided between the galvanometer mirror 42 and the first mirror 45. When the measurement light reflected by the galvanometer mirror 42 takes an optical path that passes through the slit (illumination optical path), the measurement light reaches the first mirror 45, and when the measurement light takes an optical path that does not pass through the slit (retraction optical path), the measurement light is blocked by the slit member 44. Note that the slit member 44 functions as an aperture, but instead, a member having a structure such as an iris, a pinhole, or a knife edge (a slit with one edge) that has a similar function can be used.

[0047] The first mirror 45 is arranged to reflect the measurement light reflected by the galvanometer mirror 42 toward a second mirror 46 provided in the suction box 11 of the transport device 10. Through-holes 24a and 11a are formed in the cover body 24 of the transport device 10 and the side plate of the suction box 11, respectively, through which the optical path of the measurement light directed toward the second mirror 46 passes. The through-hole 11a provided in the suction box 11 is a two-step hole with a large-diameter portion 11b on the outside and a small-diameter portion 11c on the inside. A glass plate 25 is fitted into the large-diameter portion 11b to hermetically seal the through-hole 11a. Thus, the measurement light reflected by the first mirror 45 passes through the through-hole 24a and the glass plate 25 provided in the through-hole 11a, and reaches the second mirror 46 in the suction box 11.

[0048] As described above, the second mirror 46 is provided in the suction box 11 of the conveying device 10, and reflects the measurement light reflected by the first mirror 45 upward, passing through the slit 12 provided in the suction box 11 of the conveying device 10 and between the conveying belts 15 and 16, and passing through the measurement position P set on the conveying path.

[0049] In the irradiation device 40 of this example, a collimator for collimating the wavelength swept light emitted from the light source device 35 may be further provided between the light source device 35 and the beam splitter 41 .

[0050] The reference light receiving device 50 detects the reference light dispersed by the beam splitter 41, and outputs an A / D converted digital signal as a reference signal.

[0051] The measurement light receiving device 51 is arranged above the measurement position P, detects the measurement light (object light) that has passed through the measurement object M located at the measurement position P, and outputs an A / D converted digital signal as a measurement signal.

[0052] As described above, the object detection sensor 55 is provided at an appropriate position set upstream of the measurement position P, detects the measurement object M transported by the transport device 10, and outputs a detection signal to the control device 65. Note that, although an optical type can be exemplified as the object detection sensor 55, it is not limited to this, and any conventionally known object detection sensor can be used within an applicable range.

[0053] As described above, the sorting device 60 is provided at the end of the conveyance path of the conveying device 10, and includes a sorting and recovery mechanism (not shown), a non-defective product recovery chamber, and a defective product recovery chamber, and drives the sorting and recovery mechanism in accordance with commands from the control device 65 to recover non-defective products and defective products in the defective product recovery chamber among the measurement objects M conveyed to the end of the conveyance path of the conveying device 10. Note that the sorting and recovery mechanism can be exemplified by a mechanism configured to suck and recover the measurement objects M by negative pressure.

[0054] The control device 65 controls the operations of the vibrating feeder 4, the alignment table 6, the exhaust pump 17 and drive motor 22 of the conveying device 10, the light source device 35, the motor 43 of the irradiation device 40, the sorting and recovery mechanism of the sorting device 60, etc. In particular, when the object detection sensor 55 detects the measurement target M, the control device 65 drives the motor 43 of the irradiation device 40 to switch the optical path of the measurement light reflected by the galvanometer mirror 42.

[0055] Specifically, when the object to be measured M is detected by the object detection sensor 55 and the control device 65 receives a detection signal from the object detection sensor 55, the control device 65 calculates the conveying speed of the object to be measured M being conveyed by the conveying belts 15, 16 based on the rotational speed of the drive motor 22 detected by the rotary encoder 23 at that time.

[0056] Next, based on the calculated conveying speed and the previously acquired distance between the detection position of the object detection sensor 55 and the measurement position P, the control device 65 calculates the time (timing) from the time of detection of the measurement object M detected by the object detection sensor 55 to the measurement position P, and when the calculated time has elapsed, until the measurement object M passes the measurement position P, the control device 65 drives the motor 43 to switch the optical path of the measurement light reflected by the galvanometer mirror 42 to an optical path (irradiation optical path) that passes through the slit hole of the slit member 44 (optical path shown by solid lines in Figures 5 and 6), and then, shortly before the measurement object M passes the measurement position P, the control device 65 drives the motor 43 again to switch the optical path of the measurement light reflected by the galvanometer mirror 42 to an optical path (retreat optical path) that does not pass through the slit hole of the slit member 44 (optical path shown by dashed two-dot lines in Figures 5 and 6). As a result of the above, the measurement light is irradiated onto the measurement position P only when the measurement object M is at the measurement position P; in other words, when the measurement object M is not at the measurement position P, the measurement light is not irradiated onto the measurement position P.

[0057] Furthermore, the time that the transported measurement object M is present at the measurement position P can be calculated based on the size of the measurement object M in the transport direction (diameter in this example) and the transport speed of the measurement object M.

[0058] The calculation device 70 receives the output signal of the measurement light receiving device 51 that detects the object light and the output signal of the reference light receiving device 50 that detects the reference light, processes these signals, and detects (measures) the optical characteristics of the object to be measured M.

[0059] In wavelength-swept spectroscopy, there is a one-to-one correspondence between time and wavelength in the wavelength-swept light, and this correspondence is naturally also held by the reference light and is also inherited by the object light. Utilizing this correspondence between time and wavelength, the computing device 70 detects (measures) the optical characteristics of the measurement object M.

[0060] The output signal of the measurement light receiving device 51 is D1, the time waveform of the object light indicated by this output signal D1 is IOBJ(t), the output signal of the reference light receiving device 50 is D2, and the time waveform of the reference light indicated by this output signal D2 is IREF(t).The calculation device 70, for example, converts the time waveform of the object light IOBJ(t) into a frequency domain spectrum IOBJ(λ), and similarly converts the time waveform of the reference light IREF(t) into a spectrum and appropriately scales it to calculate the reference spectrum IREF(λ).

[0061] The processing in the calculation device 70 is not particularly limited, but as an example, the calculation device 70 calculates the transmittance T(λ) as an optical characteristic of the measurement target M based on the reference spectrum IREF(λ) and the spectrum IOBJ(λ) of the object light using the following formula, and determines whether it is good or bad: T(λ)=IOBJ(λ) / IREF(λ).

[0062] 8 is an explanatory diagram illustrating spectroscopy by the light measurement device 1 of this example. As described above, since the wavelength swept light has a one-to-one correspondence between time t and wavelength λ, the time waveform IREF(t) can be converted into a frequency domain spectrum IREF(λ).

[0063] The time waveform IOBJ(t) of the object beam also has a one-to-one correspondence between time t and wavelength λ, so the waveform IOBJ(t) of the object beam can be converted into the spectrum IOBJ(λ) of the object beam.

[0064] The calculation device 70 calculates the transmission spectrum T(λ) of the measurement object M based on the ratio IOBJ(λ) / IREF(λ) of the two spectra IOBJ(λ) and IREF(λ). The optical characteristics of the measurement object M are expressed by this transmission spectrum T(λ).

[0065] If the relationship between wavelength λ and time t in wavelength swept light is expressed by the function λ = f(t), then, most simply, wavelength λ changes linearly with time t according to a linear function. This means that when the time waveform IOBJ(t) of the object light drops at a certain time tx, the transmission spectrum T(λ) has an absorption spectrum at wavelength λx = f(tx).

[0066] Note that the processing in the calculation device 70 is not limited to this. After calculating the ratio T(t) = IOBJ(t) / IREF(t) of two time waveforms IOBJ(t) and IREF(t), the transmission spectrum T(λ) may be calculated by converting the variable t of this time waveform T(t) to λ.

[0067] The control device 65 and the arithmetic device 70 are configured by a computer including a CPU, RAM, ROM, etc., and may be configured by separate computers or by a single computer.

[0068] According to the light measurement device 1 of this embodiment having the above configuration, the optical characteristics of the measurement object M are measured as follows.

[0069] First, under the control of the control device 65, the vibrating feeder 4, the alignment table 6, and the exhaust pump 17 and drive motor 22 of the conveying device 10 are driven, and the measurement objects M put into the hopper 3 are aligned in a line by passing sequentially through the vibrating feeder 4 and the alignment table 6, and are supplied in this aligned state to the conveying device 10. Then, the measurement objects M sequentially supplied to the conveying device 10 are adsorbed and conveyed while straddling the conveying belts 15, 16. Therefore, the measurement objects M are conveyed in a stable posture, and are conveyed on the adsorption conveying path without deviating from the adsorption conveying path.

[0070] The control device 65 also drives the light source device 35 to emit wavelength-swept light. The wavelength-swept light emitted from the light source device 35 is split into two beams by the beam splitter 41, one of which is transmitted in the emission direction to become measurement light, and the other is reflected and received by the reference-light receiving device 50 as reference light. At this time, the galvanometer mirror 42 is in a position where the reflected measurement light takes an optical path (avoidance optical path) (the optical path shown by the two-dot chain line in FIGS. 5 and 6 ) that does not pass through the slit hole of the slit member 44 (the position shown by the two-dot chain line in FIGS. 5 and 6 ). Therefore, at this point, the measurement light does not enter the measurement-light receiving device 51.

[0071] When the control device 65 receives a detection signal from the object detection sensor 55 after detecting the measurement object M being transported sequentially by the transport device 10, the control device 65 calculates the time (timing) from the time of detection of the measurement object M detected by the object detection sensor 55 to the measurement position P based on the rotational speed of the drive motor 22 detected by the rotary encoder 23, and when the calculated time has elapsed, drives the motor 43 to switch the optical path of the measurement light reflected by the galvanometer mirror 42 to an optical path (irradiation optical path) that passes through the slit hole in the slit member 44.

[0072] As a result, the measurement light is sequentially reflected by the first mirror 45 and the second mirror 46, incident on the measurement object M located at the measurement position P, passes through the measurement object M, and is received as object light by the measurement light receiving device 51. Next, the control device 65 maintains the optical path of the measurement light as the irradiation optical path until the measurement object M passes the measurement position P, and then, shortly before the measurement object M passes the measurement position P, drives the motor 43 again to switch the optical path of the measurement light reflected by the galvanometer mirror 42 to an optical path (light-blocking optical path) that does not pass through the slit hole of the slit member 44. As described above, the measurement light is irradiated onto the measurement position P only when the measurement object M is located at the measurement position P, and the measurement light is not irradiated onto the measurement position P when the measurement object M is not located at the measurement position P.

[0073] Since the measurement object M is transported in a stable position to the measurement position P by suction and transport, the measurement light can be reliably irradiated onto the measurement object M at the measurement position P. Furthermore, since the measurement object M is transported by suction and straddling the transport belts 15 and 16, the measurement light passes between the transport belts 15 and 16, passes only through the measurement object M, and is received by the measurement light receiving device 51.

[0074] When the object light is received by the measurement light receiving device 51, the output signal from the measurement light receiving device 51 is transmitted to the calculation device 70, and the calculation device 70 measures the optical characteristics of the object M to be measured based on the output signal of the object light received from the measurement light receiving device 51 and the output signal of the reference light received from the reference light receiving device 50, determines whether the characteristics are good or bad, and transmits the determination result to the control device 65.

[0075] Then, the control device 65 drives the sorting and recovery mechanism of the sorting device 60 based on the judgment result received from the calculation device 70 to recover non-defective products in a non-defective product recovery room and recover defective products in a defective product recovery room. The control device 65 calculates the time (timing) from the time of detection of the measurement object M detected by the object detection sensor 55 until it reaches the sorting and recovery mechanism based on the conveying speed of the measurement object M and the previously acquired distance between the detection position of the object detection sensor 55 and the sorting and recovery mechanism, and drives the sorting and recovery mechanism when the corresponding measurement object M reaches the sorting and recovery mechanism.

[0076] By the above operation, the optical characteristics of the measurement objects M transported in a random order by the transport device 10 are measured in sequence, and the objects are sorted into non-defective and defective based on the measurement results.

[0077] In this way, according to the optical measurement device 1 of this example, only when the measurement object M is at the measurement position P, the measurement light is irradiated onto the measurement position P and received by the measurement light receiving device 51, and when the measurement object M is not at the measurement position P, the measurement light is not irradiated onto the measurement position P, in other words, it is possible to prevent the measurement light from being received by the measurement light receiving device 51. Therefore, it is possible to prevent the high-power wavelength swept light from being received directly by the measurement light receiving device 51, and to avoid damage to the measurement light receiving device 51 due to the wavelength swept light being received directly by the measurement light receiving device 51.

[0078] The effect of this light measurement device 1 was verified as follows: The beam diameter of the wavelength swept light (measurement light) emitted from the light source device 35 was set to 0.8 mm (1 / e ２ The diameter of the slit member 44 was set to 1 mm, and the width of the slit hole of the slit member 44 was set to 2 mm. The distance (retraction distance) between the irradiation light path and the light blocking light path on the lower surface of the slit member 44 was set to 3 mm.

[0079] When the measurement target M was not present at the measurement position P, the intensity of light incident on the measurement light receiving device 51 was measured for each of the cases where the measurement light optical path was the irradiation optical path and the light-blocking optical path. The incident intensity was 58 mW for the irradiation optical path, while the incident intensity was 12 μW for the light-blocking optical path, which was a decrease to 0.021%. This value is well below the allowable input (damage threshold) of the measurement light receiving device 51.

[0080] The width of the slit of the slit member 44 and the retraction distance can be determined experimentally taking into account the damage threshold of the measurement light receiving device 51, the beam diameter of the measurement light, and the performance (speed) of the optical path switching unit (galvanometer mirror 42 and motor 43).

[0081] Although one embodiment of the present invention has been described above, the specific aspects that the present invention can adopt are not limited to the above example.

[0082] For example, in the above example, the slit member 44 that functions as an aperture is provided, but the present invention is not limited to this configuration, and such an aperture does not have to be provided as long as the intensity of light incident on the measurement light receiving device 51 can be sufficiently reduced when the optical path of the measurement light is set as the evacuation optical path. However, providing an aperture can prevent the measurement light from becoming stray light.

[0083] In the above example, the optical path of the measurement light is switched between the irradiation optical path and the retraction optical path by the optical path switching unit composed of the galvanometer mirror 42 and the motor 43. However, this configuration is not limited to this. For example, as shown in FIG. 9, an irradiation device 41' may be provided in which a third mirror 47 is provided instead of the galvanometer mirror 42 and a light-blocking member 48 that switches between a transmission state and a non-transmission state is provided instead of the slit member 44. The optical measurement device 1' of this example differs from the above-described optical measurement device 1 only in this configuration, and is otherwise identical to the optical measurement device 1. For this reason, in FIG. 9, the same components as those of the optical measurement device 1 of the above example shown in FIG. 6 are denoted by the same reference numerals. The non-transmission state includes not only a case where light transmission is completely blocked, but also a state where the transmitted light is dimmed.

[0084] In this optical measurement device 1', when the object detection sensor 55 detects the measurement object M being transported sequentially by the transport device 10 and the control device 65 receives the detection signal from the object detection sensor 55, the control device 65 calculates the time (timing) from the time of detection of the measurement object M detected by the object detection sensor 55 to the measurement position P based on the rotational speed of the drive motor 22 detected by the rotary encoder 23, as in the above example, and when the calculated time has elapsed, switches the light-shielding member 48, which is in an opaque state, to a transparent state.

[0085] As a result, the measurement light reflected by the third mirror 47 passes through the light-shielding member 48, is reflected sequentially by the first mirror 45 and the second mirror 46, and is incident on the measurement object M located at the measurement position P. After passing through the measurement object M, the measurement light is received as object light by the measurement light receiving device 51. On the other hand, when the light-shielding member 48 is in the non-transmitting state, the measurement light reflected by the third mirror 47 is blocked by the light-shielding member 48 and does not reach the measurement position P in its original state.

[0086] Then, the control device 65 maintains the light-blocking member 48 in the transmitting state until the measurement object M passes the measurement position P, and then switches the light-blocking member 48 to the non-transmitting state again shortly before the measurement object M passes the measurement position P. As described above, the measurement light is irradiated onto the measurement position P only when the measurement object M is at the measurement position P, and when the measurement object M is not at the measurement position P, the measurement light is not irradiated onto the measurement position P, or the measurement light irradiated onto the measurement position P can be reduced.

[0087] Thus, even with the optical measuring device 1' having such a configuration, it is possible to prevent high-power wavelength swept light from being received directly by the measurement light receiving device 51, and it is possible to avoid damage to the measurement light receiving device 51 due to the wavelength swept light being received directly by the measurement light receiving device 51.

[0088] Examples of the light-blocking member 48 include a movable shutter or a variable attenuator, and examples of the variable attenuator include a liquid crystal shutter, an acousto-optical modulator (AOM), an electro-optical modulator (EOM), etc.

[0089] In addition, in each of the above examples, the control device 65 calculates the conveying speed of the measurement object M conveyed by the conveying belts 15, 16 based on the rotational speed of the drive motor 22 detected by the rotary encoder 23, and calculates the time (timing) from the time of detection of the measurement object M detected by the object detection sensor 55 to the measurement position P based on the calculated conveying speed and the distance between the detection position of the object detection sensor 55 and the measurement position P, which has been obtained in advance.However, the estimation of the timing from the time of detection of the measurement object M to the measurement position P is not limited to such a method.

[0090] For example, as described above, the rotary encoder 23 detects the rotation angle per unit time of the drive motor 22, and therefore the rotary encoder 23 can detect the amount of movement of the conveyor belts 15, 16, in other words, the amount of movement of the object to be measured M, and based on this amount of movement, the timing at which the object to be measured M reaches the measurement position P from the time of detection can be estimated.

[0091] REFERENCE SIGNS LIST 1 Light measurement device 2 Supply unit 3 Hopper 4 Vibration feeder 5 Chute 6 Alignment table 10 Conveying device 11 Suction box 11a Through hole 12 Slit 13, 14 Guide groove 15, 16 Conveying belt 17 Exhaust pump 18 Drive pulley 19, 20, 21 Driven pulley 22 Drive motor 23 Rotary encoder (speed detection sensor) 24 Cover body 24a Through hole 25 Glass plate 30 Cover body 35 Light source device 40 Irradiation device 41 Beam splitter 42 Galvanometer mirror 43 Motor 44 Slit member 45 First mirror 46 Second mirror 50 Reference light receiving device 51 Light receiving device 55 Object detection sensor 60 Sorting device 65 Control device 70 Calculation device

Claims

1. A measuring device comprising: a light source device that generates wavelength swept light; a conveying device having two endless annular conveying belts arranged opposite to each other to form a linear conveying path and a drive unit that rotates the conveying belts, and conveying a measurement object along the conveying path while straddling the two conveying belts; an irradiation device having an optical path for guiding and irradiating the wavelength swept light generated by the light source device to a measurement position set on the conveying path, and arranged on the optical path and having an optical path switching unit that switches the optical path of the wavelength swept light; a light receiving device that receives the wavelength swept light irradiated to the measurement position by the irradiation device; an object detection sensor that is arranged upstream of the measurement position in the conveying direction of the conveying device and detects the measurement object conveyed by the conveying device; a conveying detection sensor that detects the conveying speed or displacement in the conveying direction of the conveying belts; and a control device that controls the drive unit of the conveying device and the optical path switching unit of the irradiation device, The control device estimates the timing when the object to be measured will reach the measurement position based on detection by the object detection sensor and the displacement in the conveying direction or the conveying speed detected by the conveying detection sensor, and controls the optical path switching unit in synchronization with the estimated timing to set an optical path in which the wavelength swept light is received by a light receiving device while the object to be measured is present at the measurement position, and sets an optical path in which the wavelength swept light is not received by a light receiving device while the object to be measured is not present at the measurement position.

2. The optical measurement device according to claim 1, wherein the optical path switching section includes any one of a galvanometer mirror, a MEMS (Micro Electro Mechanical Systems) mirror, a piezoelectric driven mirror, and a polygon mirror.

3. The light measuring device according to claim 2, wherein said irradiation device further comprises an aperture on the output side of said light path switching section.

4. A measuring device comprising: a light source device that generates wavelength swept light; a conveying device having two endless annular conveying belts arranged opposite to each other to form a linear conveying path and a drive unit that rotates the conveying belts, and conveying a measurement object along the conveying path while straddling the two conveying belts; an irradiation device having an optical path for guiding and irradiating the wavelength swept light generated by the light source device to a measurement position set on the conveying path, and arranged on the optical path and having a light blocking unit that switches between transmitting and blocking the wavelength swept light; a light receiving device that receives the wavelength swept light irradiated to the measurement position by the irradiation device; an object detection sensor that is arranged upstream of the measurement position in the conveying direction of the conveying device and detects the measurement object conveyed by the conveying device; a conveying detection sensor that detects the conveying speed or displacement in the conveying direction of the conveying belts; and a control device that controls the drive unit of the conveying device and the light blocking unit of the irradiation device, The control device is an optical measurement device configured to estimate the timing when the object to be measured will reach the measurement position based on detection by the object detection sensor and the displacement in the conveying speed or conveying direction detected by the conveying detection sensor, and to control the shading part in synchronization with the estimated timing to make the shading part transparent while the object to be measured is present at the measurement position, and to make the shading part opaque while the object to be measured is not present at the measurement position.

5. The optical measurement device according to claim 4, wherein the light blocking section includes either a movable shutter or a variable attenuator.

6. The optical measurement device according to claim 5, wherein said variable attenuator comprises any one of a liquid crystal shutter, an acousto-optic modulator, and an electro-optic modulator.

7. An optical measurement device according to any one of claims 1 to 6, wherein the wavelength swept light is adapted to pass between the two conveyor belts and be irradiated onto the object to be measured.

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