Non-destructive measurement device and non-destructive measurement method for fruits and vegetables

Abstract

Provided are a non-destructive measurement device and a non-destructive measurement method which make it possible to acquire a plurality of pieces of information in a depth direction of fruits and vegetables and to acquire internal information about thick-skinned fruits and vegetables.　The present invention comprises: a grip part K2 which can be gripped; a housing K including a measurement unit K1 having an annular contact part 7 for abutting on fruits and vegetables AS; a ring lens 8 which is arranged in an annular shape smaller than the contact part 7 in an inner part surrounded by the contact part 7, and which annularly emits light emitted from a light source group 14dG to the outside of the housing K; a light guide member 11 that emits incident light from one end surface 11a1 on the inner side of the ring lens 8 inside the housing K to the outside from another end surface 11fb; a photosensor 13c that is disposed in the housing K and receives the light emitted from the other end surface 11fb of the light guide member 11; and a light intensity processing unit CT3 that obtains absorbance on the basis of the light reception intensity. The light source group 14dG is controlled by a light quantity control unit CT5 so as to emit light of at least two different light quantities.

Description

Non-destructive measuring device and non-destructive measuring method for fruits and vegetables

[0001] The present invention relates to a non-destructive measuring device and method for measuring the absorbance of fruits and vegetables in a non-destructive manner.

[0002] Non-destructive measuring devices for measuring the absorbance of fruits and vegetables are known. For example, there is a non-destructive measuring device that measures absorbance using near-infrared light that is irradiated onto fruits and vegetables and transmitted through them, and obtains the sugar content of the fruits and vegetables as a Brix value based on the measured absorbance. This non-destructive measuring device is described in Patent Document 1 as a non-destructive sugar content measuring device.

[0003] The non-destructive measuring device described in Patent Document 1 is used to measure harvested fruits and vegetables. Furthermore, the device is large in size because the harvested fruits and vegetables are placed on a conveyor to measure the absorbance.

[0004] Fruit and vegetable producers are looking for a device that can measure the absorbance of harvested fruits and vegetables in a non-destructive manner to determine the sugar content, not only for harvested fruits and vegetables but also for fruits and vegetables that are still growing on trees before harvest, in order to determine the harvest time, etc. Specifically, there is a demand for a non-destructive measuring device that is small enough to be held in one hand so that it can be easily used on growing fruits and vegetables.

[0005] When a nondestructive measuring device is made small enough to be held in one hand, the use of a light emitting diode (LED) as the light source is considered from the viewpoint of space saving and power consumption saving.

[0006] Patent Document 2 discloses a nondestructive measuring device that nondestructively measures the absorbance of a measurement object such as fruit or vegetables, and that uses a light-emitting diode as a light source.

[0007] In non-destructive measurement of fruits and vegetables, it is necessary to irradiate them with near-infrared light and accurately measure the absorbance information of the light that passes through the interior of the fruit or vegetable, but for large items such as melons and citrus fruits, the thick skin prevents sufficient light from penetrating deep into the interior, making it difficult to obtain absorbance information on the sugar content inside. Also, a light source with a strong intensity is required to allow light to enter the interior, but previous methods for driving light-emitting diodes have had the problem of not allowing enough light to enter the interior of the fruit or vegetable due to the low light intensity.

[0008] Furthermore, in order to create a calibration curve for the sugar content of fruits and vegetables, it is necessary to obtain a certain amount of information on the sugar content range for the fruits and vegetables to be measured. However, for example, the sugar content of watermelon is almost the same near the center, and there is little (small) individual variation. Therefore, simply measuring a large number of samples results in the measured values ​​concentrating at one point, making it difficult to create a calibration curve.

[0009] JP 2002-014042 A

[0010] Therefore, an object of the present invention is to provide a non-destructive measuring device and a non-destructive measuring method that enable the acquisition of multiple pieces of information in the depth direction of fruits and vegetables, and also enable the acquisition of internal information of fruits and vegetables with thick skin.

[0011] In order to solve the above problems, the non-destructive measuring device for fruits and vegetables of the present invention comprises a housing formed to include a grip portion that can be grasped and a measuring portion having an annular abutment portion for abutting against the fruit or vegetable; a light source group consisting of a plurality of light sources arranged circumferentially spaced apart inside the housing; a light intensity control portion that controls the amount of light emitted by the light source group; a ring lens arranged in an inner portion surrounded by the abutment portion and having a ring shape smaller than the abutment portion, and emitting light emitted from the light source group in a ring shape to the outside of the housing; a light-guiding member having one end face exposed inside the ring lens and the other end face located inside the housing and emitting light incident from the one end face to the outside from the other end face; a photosensor arranged inside the housing and receiving light emitted from the other end face of the light-guiding member; and a light intensity processing portion that determines absorbance based on the intensity of light received by the photosensor, wherein the light source group is controlled by the light intensity control portion to emit light of at least two different intensities.

[0012] The light intensity processing unit may determine the Brix value distribution in the depth direction of the fruit or vegetable based on the absorbance of light of at least two different light intensities.

[0013] The light intensity processing unit may obtain a calibration curve of the sugar content of the fruit or vegetable based on the absorbance of light at least two different intensities of light and the Brix value at a depth in the fruit or vegetable corresponding to the light intensity.

[0014] An electric circuit may be provided that charges the electrolytic capacitor from a power source when no light is emitted, and supplies current to the light source group from the power source and the electrolytic capacitor when light is emitted.

[0015] An annular relay lens may be provided between the light source group and the ring lens to guide light from the light source group to the ring lens.

[0016] The main optical axis of the ring-shaped light emitted from the ring lens may be tilted in a direction in which the diameter of the light decreases after it has exited the ring lens.

[0017] At least m (m is an integer of 2 or more) photosensors may be provided, and bandpass filters having center wavelengths of m different wavelengths λ1 to λm may be provided between each of the m photosensors and the other end face of the light-guiding member.

[0018] The light intensity processing unit may determine the absorbance based on the received light intensity corresponding to each of the wavelengths λ1 to λm obtained by the m photosensors, and may also calculate the Brix value from the determined absorbance.

[0019] The grip portion has a longitudinal length and is formed so as to be able to be grasped, and the measuring portion is formed at one end of the longitudinal length of the grip portion, with the extension direction of the abutment portion along the longitudinal length, and the tip surface of the abutment portion may be located in a position that protrudes beyond the surface of the grip portion.

[0020] A diffusion section for diffusing light passing through may be provided between the surface of the fruit or vegetable surrounded by the contact section and the other end face of the light-guiding member when the fruit or vegetable is in contact with the contact section.

[0021] In addition, the non-destructive measurement method for fruits and vegetables of the present invention is a non-destructive measurement method for fruits and vegetables, and includes a fruit and vegetable contacting step of bringing the fruit and vegetable into contact with a measuring unit; a light emitting step of emitting light from a group of light sources consisting of multiple light sources toward the fruit and vegetable and causing it to enter the interior of the fruit and vegetable; a light receiving step of receiving with a photosensor the light that is diffusely reflected inside the fruit and vegetable and is partially absorbed with characteristics corresponding to the state of the fruit and vegetable and emitted to the outside; and a light intensity processing step of determining absorbance based on the light intensity received by the photosensor, wherein the light emitting step is a multi-stage light emitting step of emitting light of at least two different intensities.

[0022] The light intensity processing step may include a step of determining a Brix value distribution in the depth direction of the fruit or vegetable based on the absorbance of light of at least two different light intensities.

[0023] The light intensity processing step may include a step of obtaining a calibration curve of the sugar content of the fruit or vegetable based on the absorbance of light at least two different light intensities and the Brix value at a depth in the fruit or vegetable corresponding to the light intensities.

[0024] The multi-stage light emission step may include a step of charging an electrolytic capacitor from a power source when no light is emitted, and supplying current to the light source group from the power source and the electrolytic capacitor when light is emitted.

[0025] According to the present invention, it is possible to provide a non-destructive measuring device and a non-destructive measuring method that enable the acquisition of multiple pieces of information in the depth direction of fruits and vegetables, and also enable the acquisition of internal information of fruits and vegetables with thick skin.

[0026] FIG. 1 is an external perspective view illustrating a handheld non-destructive saccharimeter 51 (saccharimeter 51), which is an example of a non-destructive measuring device for fruits and vegetables according to an embodiment of the present invention. FIG. 2 is a front view of the saccharimeter 51. FIG. 3 is a cross-sectional view taken along the line S3-S3 in FIG. 2. FIG. 4 is an assembly diagram of the saccharimeter 51. FIG. 5 is a front view of a sensor substrate 13 included in the saccharimeter 51. FIG. 6 is a front view of a base substrate 14 included in the saccharimeter 51. FIG. 7 is a partial cross-sectional view illustrating the attachment state of a relay lens 18 included in the saccharimeter 51. FIG. 8 is a half-cross-sectional view of a ring lens 8 included in the saccharimeter 51. FIG. 9 is an assembly diagram illustrating a filter unit F included in the saccharimeter 51. FIG. 10 is a rear view of the filter unit F. FIG. 11 is a perspective view of a light-guiding member 11 included in the saccharimeter 51. FIG. 12 is a two-sided view of the light-guiding member 11, where (a) is a half-sectional side view and (b) is a rear view. FIG. 13 is an enlarged cross-sectional view of the SB section in FIG. 3 . FIG. 14 is a diagram illustrating the control system of saccharimeter 51. FIG. 15 is a diagram illustrating a measurement mode when saccharimeter 51 is placed on a desk. FIG. 16 is a diagram illustrating a measurement mode when saccharimeter 51 is held in a hand. FIG. 17 is a partial cross-sectional view illustrating the light path in saccharimeter 51. FIG. 18 is a half cross-sectional view illustrating standard lid 52 used for calibrating saccharimeter 51 and its usage state. FIG. 19 is a partial cross-sectional view illustrating diffuser 41 and its attachment mode as modified example 1. FIG. 20 is a half cross-sectional view illustrating light-guiding member 11W as modified example 2. FIG. 21 is a diagram illustrating a watermelon 100 divided into four equal parts (sections A to D) from the skin to the center. FIG. 22 is a diagram illustrating the results of multiple regression analysis of measured Brix values. FIG. 23 is a diagram illustrating the results of multiple regression analysis of measured Brix values. FIG. 24 is a diagram illustrating an electrical circuit supplying current to a group of light sources from a power source and an electrolytic capacitor.

[0027] A non-destructive measuring device for fruits and vegetables according to an embodiment of the present invention will be described using a handy non-destructive sugar content meter 51 (hereinafter also simply referred to as sugar content meter 51) as an example.

[0028] First, the configuration of the saccharimeter 51 will be described with reference to Figures 1 to 4. Figure 1 is an external perspective view of the saccharimeter 51. Figure 2 is a front view of the saccharimeter 51. Figure 3 is a cross-sectional view taken along the line S3-S3 in Figure 2. Figure 4 is an assembly diagram of the saccharimeter 51.

[0029] In the following description, the up, down, left, right, front and rear directions are defined as the directions shown in Figure 1. The saccharimeter 51 is a so-called handheld type that can be held in one hand. Therefore, the up, down, left, right, front and rear directions shown in Figure 1 are defined for the convenience of explanation and do not limit the position of the saccharimeter 51 when in use.

[0030] First, we will explain the external configuration of the saccharimeter 51. The saccharimeter 51 has a roughly box-shaped box body 1 that is open at the front, and a roughly lid-shaped lid body 2 that is attached to the box body 1 so as to close the front side. As shown in Figure 3, the box body 1 has a base 1k that is formed in a roughly flat plate shape and a side wall 1h that rises forward from the periphery of the base 1k, giving it a box-like shape.

[0031] The box 1 and the lid 2 are joined together by tapping screws (not shown) with an O-ring 81 (see FIG. 3) interposed therebetween to form a housing K. The saccharimeter 51 has waterproof and dustproof properties of IP65 or higher, which is a protection characteristic defined by the IEC (International Electrotechnical Commission) standard, due to the O-ring 81 in the housing K and other sealing structures (not shown).

[0032] The housing K has an approximately cylindrical measuring section K1 formed at the top and centered on an axis CL1 extending in the front-to-rear direction, and an approximately flattened rectangular parallelepiped grip section K2 extending downward from the rear side of the measuring section K1.

[0033] The cover 2 has a front surface 2a having a generally flat front surface 2a1 in the grip section K2, and a cylindrical stage section 2b that protrudes forward relative to the front-to-rear direction position of the front surface 2a in the measurement section K1. The cover 2 has a bank section 2c that protrudes forward at the left edge of the front surface 2a. The bank section 2c is a portion that serves as a fingertip when the device is held as described below.

[0034] The axis CL1 of the measuring part K1 coincides with a light-receiving axis CLT, which is set as a virtual optical axis of light received by a photosensor 13c, which will be described later.

[0035] In the grip section K2, the front surface 2a1 of the cover body 2 is provided with a display section 3 that visibly displays numbers, letters, and symbols using a display element 14f (see Figures 3 and 6), and a switch section 4 that includes multiple switch pressing sections 4a that can be pressed with a finger to select an operating mode or reset to zero.

[0036] The display unit 3 displays, under the control of the control unit CT (see FIGS. 3 and 14), for example, the operating status of the sugar content meter 51, the remaining battery level, and the sugar content (Brix value) obtained by measurement.

[0037] A battery box 1b (see FIG. 3) for accommodating batteries is formed in the left rear portion of the interior of the box 1, with an opening 1b1 on the underside 1c. A battery cover 5 is detachably attached to the opening 1b1. The battery box 1b accommodates, for example, AAA dry batteries as a power source for the saccharimeter 51, which can be inserted and removed (hereinafter referred to as "insertable" or "removable") through the opening 1b1 by the user.

[0038] A push button 6 is provided on the upper right of the box 1. Each time the push button 6 is pressed by a user or the like, an internal switch 13d (see FIGS. 4 and 5) is operated to alternately start and stop the measurement.

[0039] The grip portion K2 is sized to be held in one hand by an adult. When using this saccharimeter 51, for example, by holding the grip portion K2 with the right hand, the user places the palm of their hand on the rear surface 1a of the case 1, and the four fingers from the index finger to the little finger naturally rest on the mound portion 2c, allowing the user to comfortably grip the saccharimeter 51. In this gripping state, the push button 6 is positioned so that it can be easily pressed with the thumb. In addition, a concave contact portion 1a1 (see FIG. 1) is formed on the right side of the rear surface 1a of the case 1 to fit the ball of the hand, providing a comfortable tactile contact.

[0040] The box body 1 and the lid body 2 are made of resin, for example, a near-infrared absorbing grade of black polycarbonate resin.

[0041] Next, the external configuration of the measuring unit K1 will be described in detail.

[0042] An annular outer contact portion 7 is attached to the tip of the stage portion 2b of the lid body 2. The outer contact portion 7 is made of a material that is elastic at least against rearward compression. An example of the material is sponge.

[0043] 2, in the inner portion surrounded by the outer contact portion 7, the ring lens 8, which is a lens member, the inner contact portion 9, and a portion of the front surface 10a of the stage base 10 are visible in an annular shape, in that order from the outside. The front end surface 11a1 of the light guide member 11 is visible in the center portion including the axis line CL1.

[0044] The inner contact portion 9 is formed in an annular shape and attached to the front surface 10a. The inner contact portion 9 is made of a material that is elastic at least against rearward compression. An example of the material is sponge. The inner contact portion 9 has a notch 9a that is carved outward in an arc shape in the radial direction at part of its inner edge. The temperature sensor 12 is attached to the stage base 10 so that the temperature-sensitive surface 12a is exposed to the front surface. When viewed from the front, the temperature sensor 12 is arranged with part of the temperature-sensitive surface 12a extending into the notch 9a. The temperature sensor 12 is a so-called thermopile, and detects the surface temperature T of the fruit or vegetable AS (see Figures 15 and 16) that is the object to be measured assigned to the measuring unit K1. ２ is measured without contact, and the temperature T １ The temperature sensor 12 also measures the measured temperature T １ and temperature T ２ is output to the control unit CT as temperature information JT (see FIG. 14). １ and temperature T ２ In other words, the surface temperature of the fruit or vegetable AS is set to temperature T １In the housing K, the measuring part K1 is integrally formed on one end side (upper side) of the grip part K2 in such a position that the annular extending surfaces of the outer contact part 7 and the inner contact part 9 are in line with (for example, roughly parallel to) the vertical direction, which is the longitudinal direction of the grip part K2.

[0045] Regarding the front-to-rear position of each part of the measuring unit K1, as shown in Figure 3, the front end face 9b of the inner contact portion 9 is located rearward of the front end face 7a of the outer contact portion 7. The ring lens 8 is disposed in approximately the same front-to-rear position as the inner contact portion 9. The front edge portion 8r, which is located at the front end of the ring lens 8, is located approximately in the same front-to-rear position as the front end face 9b of the inner contact portion 9. The front surface 10a of the stage base 10 is located rearward of the front end face 9b of the inner contact portion 9. The front end face 11a1 of the light-guiding member 11 is located at the same position as, or slightly rearward of, the front surface 10a of the stage base 10 in the front-to-rear direction.

[0046] Next, the components arranged inside the housing K will be described with reference to Figures 3 to 12. As shown in Figures 3 and 4, two large boards are housed inside the housing K, arranged side by side and facing each other in the front-to-rear direction. Specifically, from the base 1k side of the box 1, these are a sensor board 13 and a base board 14.

[0047] 5 is a front view illustrating the sensor board 13. The sensor board 13 has a receptacle 13b, a plurality of photosensors 13c, and a switch 13d mounted on a front surface 13a, which is the front side when the sensor board 13 is housed in the housing K.

[0048] The receptacle 13b is attached to a plug 14b of the base substrate 14 disposed in front of the sensor substrate 13, and the sensor substrate 13 and the base substrate 14 are electrically connected (see FIG. 3).

[0049] In this example, there are seven photosensors 13c. Six of the seven photosensors 13c are mounted around the light-receiving axis CLT at equal intervals of an angular pitch θp of 60°, with the center position of each photosensor 13c on the line of diameter φa. The remaining photosensor 13c is mounted at the center of diameter φa. When it is necessary to distinguish between the seven photosensors 13c in the following description, they will be distinguished as photosensors 13c1 to 13c7, as shown in FIG. 5.

[0050] In the assembled sugar content meter 51, the switch 13d alternately repeats ON and OFF operations each time the push button 6 is pressed, as described above.

[0051] The sensor substrate 13 has four through holes 13e spaced at intervals of approximately 90° at positions radially outward from the photosensor 13c.

[0052] 6 is a front view illustrating the base substrate 14. The base substrate 14 has a circular hole 14g at its top centered on the light-receiving axis CLT, a rectangular notch 14g1 carved downward at the lower edge of the hole 14g, and holes 14h at 45° angles relative to the top, bottom, left, and right on the outside of the hole 14g. The base substrate 14 has an arc-shaped portion 14j centered on the light-receiving axis CLT.

[0053] On the front surface 14a of the base substrate 14, which is the front side when housed in the housing K, are mounted a display element 14f, a switch 14s, a plurality of (n: n is an integer of 2 or more) LEDs 14d as light-emitting elements that serve as light sources, a plurality of FB (feedback) photosensors 14e, and a control unit CT that controls the operation of the saccharimeter 51. On the other hand, on the rear surface 14c, a plug 14b that connects to a receptacle 13b of the sensor substrate 13 is mounted.

[0054] The display element 14f is a display device such as a liquid crystal device or an organic electroluminescence (EL) device.

[0055] In this example, the number of LEDs 14d is 20 (n=20). The 20 LEDs 14d are mounted radially at equal intervals with an angular pitch θpa of 18° on a line of diameter φb around the hole 14g centered on the light-receiving axis CLT. More specifically, the LEDs 14d are spaced apart in the circumferential direction near the arc portion 14j. Hereinafter, the light source group formed by grouping the plurality of LEDs 14d will also be referred to as an LED group 14dG.

[0056] For example, six types of LEDs 14d are used, each with the following center wavelengths, and are arranged in order in the circumferential direction. That is, the wavelengths are 880 nm, 900 nm, 950 nm, 980 nm, 1020 nm, and 1064 nm. In this case, at least three LEDs 14d with each center wavelength are arranged among the 20 LEDs. Among them, four LEDs 14d with center wavelengths of 880 nm and four LEDs 14d with center wavelengths of 900 nm are arranged. The selection of LEDs 14d for the six wavelengths is not limited to this. As another example, a so-called three-wavelength composite LED may be used, in which three LEDs with center wavelengths at three of the short wavelengths and three of the long wavelengths are packaged together. For example, three-wavelength composite LEDs with central wavelengths of 880, 900, and 950 nm and three-wavelength composite LEDs with central wavelengths of 980, 1020, and 1064 nm may be used, and a total of 20 LEDs, for example, eight of the former and twelve of the latter, may be appropriately arranged.

[0057] Between the edge of the hole 14g and the LED 14d, four feedback (FB) photosensors 14e (hereinafter referred to as FB photosensors 14e) are mounted in the top, bottom, left, and right directions. Hereinafter, these four feedback photosensors 14e will be collectively referred to as a feedback photosensor group 14eG.

[0058] 3 and 4, a flattened cylindrical filter unit F is disposed on the sensor substrate 13 so as to cover the seven photosensors 13c. A solid light-guiding member 11 formed in a generally truncated cone shape is disposed in front of the filter unit F.

[0059] The filter unit F and the light guide member 11 are placed on the sensor substrate 13 from the front side and are sandwiched between the sensor substrate 13 and the unit holder 15 by a stage base 16 that is fastened and fixed from the rear side with tapping screws Na. The specific configurations of the light guide member 11, the stage base 16, and the filter unit F will be described later.

[0060] 3 and 4, the unit holder 15 has a pot-shaped base 15a that is open at the rear and has a bottom at the front, and a protrusion 15b that protrudes forward from the base 15a. The base 15a has four through-holes 15a1 (see FIG. 4) that extend in the front-rear direction and are formed at 45° angles relative to the up, down, left, and right directions, for inserting tapping screws Na. The protrusion 15b is formed in a hollow cone shape so that the light guide member 11 fits inside with almost no gap, and protrudes forward through a hole 14g in the base substrate 14.

[0061] The outer circumferential surface of the protruding portion 15b is formed with two stepped portions 15b1 and 15b2, at the rear side and the tip side, where the diameter changes suddenly.

[0062] The outer diameter of the protruding portion 15b is set smaller than the inner diameter of the hole 14g of the base substrate 14, and the rear end portion 16a of the stage base 16 is engaged between the hole 14g and the protruding portion 15b. The rear end portion 16a abuts against a step portion 15b1 of the protruding portion 15b, thereby determining its position in the front-to-rear direction.

[0063] The stage base 16 is formed in a generally funnel shape with a tapered rear end. A passage portion 16b that protrudes downward is formed at the rear end 16a. The outer shape of the passage portion 16b is adapted to engage with the notch portion 14g1 in the hole 14g of the base substrate 14. In other words, the position of the stage base 16 is determined around the light-receiving axis CLT of the base substrate 14.

[0064] The inner peripheral surface of the rear end portion 16a, excluding the passage portion 16b, abuts against the outer surface of the protrusion portion 15b of the unit holder 15. That is, a gap Va (see FIG. 3) is formed between the passage portion 16b and the protrusion portion 15b. This gap Va serves as a passage through which lead wires from a temperature sensor board 17 (described later) pass in the front-rear direction.

[0065] The rear end portion 16a is formed with four bosses 16a1 extending forward and backward at an angle of 45° relative to the up, down, left, and right directions in a front view. Each boss 16a1 has a bottomed hole with its front end at the bottom.

[0066] 3 is inserted through the through-hole 13e of the sensor substrate 13 and the through-hole 15a1 of the unit holder 15 and screwed into a blind hole formed in the boss 16a1 of the stage base 16, thereby fixing the unit holder 15 and the stage base 16 to the sensor substrate 13. At this time, the filter unit F and the light guide member 11 are sandwiched and held between the unit holder 15 and the sensor substrate 13.

[0067] The stage base 10 is disposed in front of the stage base 16. The stage base 10 has a disk-shaped stage bottom 10b (see FIG. 3) and an annular peripheral wall 10c that rises rearward from the periphery of the stage bottom 10b. The front surface 10a mentioned above is the front surface of the stage bottom 10b.

[0068] 3, a through-hole 10b1 is formed in the center of the stage bottom 10b (the position of the light-receiving axis CLT). Furthermore, a through-hole 10b2 is formed above the through-hole 10b1.

[0069] The tip portion of the light guide member 11 enters the through hole 10b1 from the rear side, and the front end surface 11a1 of the light guide member 11 is exposed forward. The temperature sensor 12 enters the through hole 10b2 from the rear side, and the temperature-sensitive surface 12a of the temperature sensor 12 is exposed forward.

[0070] A temperature sensor board 17 is disposed inside the peripheral wall 10c of the stage base 10. As shown in Fig. 4, the temperature sensor board 17 is disk-shaped and has a central hole 17a and a pair of through-holes 17b. The temperature sensor board 17 also has a temperature sensor 12 mounted thereon. The temperature sensor board 17 is attached to the stage bottom 10b with tapping screws (not shown) that pass through the through-holes 17b.

[0071] Lead wires (not shown) are drawn rearward from the temperature sensor board 17 and routed through the gap Va to the sensor board 13 .

[0072] The stage base 16 and the stage base 10 are made of resin. The resin is, for example, a near-infrared absorbing grade of black polycarbonate resin. The unit holder 15 is made of aluminum, and its surface is black anodized. By making the unit holder 15 out of metal, a shielding function is achieved, and the effects of external noise on the sensor substrate 13 can be reduced.

[0073] A relay lens 18 is attached to the peripheral wall 10c of the stage base 10. Next, the relay lens 18 and its attachment structure will be described mainly with reference to Fig. 7. Fig. 7 is an enlarged view of the SA portion in Fig. 3.

[0074] 7, a stepped portion 10c2, which has a slightly larger diameter on the front side, is formed around the entire periphery on the outer circumferential surface 10c1 of the peripheral wall portion 10c of the stage base 10. The relay lens 18 is attached to the stepped portion 10c2.

[0075] The relay lens 18 is an annular optical member with an inner diameter Da, and its cross section perpendicular to the extension direction has a circular diameter D. The diameter φb7 at the center position Pc of the annular portion is set equal to the diameter φb (see FIG. 6 ) at the center position of the LED 14d mounted on the base substrate 14. The relay lens 18 is formed, for example, from a transparent polycarbonate resin that is optically transparent.

[0076] The outer diameter of the outer peripheral surface 10c1 of the peripheral wall portion 10c of the stage base 10, located forward of the stepped portion 10c2, is formed with a diameter Db that is larger than the inner diameter Da of the relay lens 18. The stepped portion 10c2 gradually narrows toward the rear by a concave curved surface 10c3 with a radius R (= D / 2), and connects to a narrowed diameter portion 10c4 having an outer diameter equal to the inner diameter Da. The narrowed diameter portion 10c4 has a plurality of small protrusions 10c5 formed at predetermined intervals in the circumferential direction. The relay lens 18 is attached so that it is in close contact with the concave curved surface 10c3 facing forward, and the small protrusions 10c5 restrict rearward movement of the relay lens 18.

[0077] When attaching the relay lens 18 to the step portion 10c2, the relay lens 18 is moved while undergoing elastic deformation that widens the inner diameter from the rear side (see arrow DRa), so that it passes over the minute protrusion 10c5 and is placed between the minute protrusion 10c5 and the concave curved surface 10c3.

[0078] 3, a seal ring 19 is tightly fitted between the relay lens 18 and the inner surface 2b1 of the stage portion 2b of the lid 2. The seal ring 19 is formed, for example, from a metal spring wire. The seal ring 19 presses the relay lens 18 against the stage base 10 by the elastic repulsive force of the tight fit, so that the position of the relay lens 18 is more reliably maintained without deviation.

[0079] The previously described ring lens 8 is attached in front of the relay lens 18, facing the relay lens 18 in the front-to-rear direction. The ring lens 8 is formed, for example, from a transparent polycarbonate resin that is optically transparent. Figure 8 is a half cross-sectional view (with some cutaway portions omitted) for explaining the ring lens 8.

[0080] 8, the ring lens 8 has an annular base 8a having a hole 8a1 and formed in an annular shape, a deflection portion 8b extending radially outward and forward from the annular base 8a at an angle, and a flange portion 8c extending radially outward from the deflection portion 8b. The annular base 8a, the deflection portion 8b, and the flange portion 8c are formed in an annular shape around an axis CL8 extending in the front-to-rear direction.

[0081] The deflection portion 8b has a rearward light-entering surface 8b1 and a forward light-exiting surface 8b2. The light-entering surface 8b1 is a conical peripheral surface that passes through an imaginary reference circle P1 having a diameter Dc and is inclined at an inclination angle θa so that the light-exiting surface 8b2 becomes more forward as it moves away from the axis CL8. When the intersection of a plane including the axis CL8 and the imaginary reference circle P1 is defined as point P1a, the cross-sectional shape of the light-exiting surface 8b2 shown in FIG. 8 is formed as a curved surface that extends in the circumferential direction and has a cross-sectional arc shape with a radius Ra centered at point P1a.

[0082] In the radial range in which the light incident surface 8b1 is formed, the inner edge 8b1a has a diameter Dd, which is smaller than the diameter Dc, and the outer edge 8b1b has a diameter De, which is larger than the diameter Dc. The radial range in which the light exit surface 8b2 is formed includes at least the radial range in which the light incident surface 8b1 is formed. Specifically, the inner edge 8b2a of the light exit surface 8b2 has a diameter Dd1, which is smaller than the diameter Dd, and the outer edge 8b2b has a diameter De1, which is larger than the diameter De.

[0083] The flange portion 8c has, at its front, an annular flat portion 8c1 that is connected to the outer diameter edge portion 8b2b of the light output surface 8b2 and is perpendicular to the axis CL8, and an annular shelf portion 8c2 that is formed radially outside the flat portion 8c1 in a stepped manner relative to the flat portion 8c1 and is located on the rear side.

[0084] 3, the ring lens 8 is attached so as to seal the gap between the peripheral edge of the front surface 10a of the stage base 10 and the inner surface 2b1 of the stage portion 2b of the lid 2. More specifically, the hole 8a1 of the annular base 8a engages with a step formed on the peripheral edge of the front surface 10a of the stage base 10, and is sealed with an O-ring (not shown) and fixed with an adhesive. The flat surface 8c1 of the flange portion 8c abuts against the rear surface of the inner flange 2b2 formed to protrude inward at the tip of the stage portion 2b, and an O-ring 82 is interposed between the rear surface and the shelf portion 8c2.

[0085] Next, the filter unit F will be described with reference to Figures 9 and 10. The filter unit F is configured to include a disk-shaped filter holder 20, a disk-shaped holder cover 21 that engages with the filter holder 20 in the direction of the axis CLf of the filter holder 20, and a plurality of (seven in this example) optical bandpass filters, namely bandpass filters 31 to 37, that are sandwiched between the filter holder 20 and the holder cover 21. The seven bandpass filters 31 to 37 each have a rectangular outer shape and have bandpass characteristics with different center wavelengths.

[0086] The filter holder 20 and the holder cover 21 are made of resin, such as a black polycarbonate resin of near-infrared absorbing grade.

[0087] The wavelengths at which absorbance is measured are selected based on the absorption wavelength of sugar (m is an integer of 2 or greater). In this example, seven wavelengths λ1 to λ7, where m=7, are selected. Furthermore, m photosensors 13c1 to 13c7 are provided as photosensors 13c1 to 13c7. That is, the center wavelengths of bandpass filters 31 to 37 are wavelengths λ1 to λ7 selected and set based on the conventionally known absorption wavelengths of sugar. Furthermore, LEDs 14d are selected to have emission center wavelengths corresponding to the respective center wavelengths λ1 to λ7. Specifically, LEDs 14d are selected to have emission center wavelengths equal to or close to the respective center wavelengths λ1 to λ7. In this example, the selected center wavelengths λ1 to λ7 are as follows: The wavelengths in parentheses are the emission center wavelengths of LEDs 14d selected and used corresponding to bandpass filters 31 to 37, respectively. Bandpass filter 31... λ1: 875 nm (880 nm) Bandpass filter 32... λ2: 900 nm (900 nm) Bandpass filter 33... λ3: 950 nm (950 nm) Bandpass filter 34... λ4: 980 nm (980 nm) Bandpass filter 35... λ5: 1020 nm (1020 nm) Bandpass filter 36... λ6: 1050 nm (1064 nm) Bandpass filter 37... λ7: 1064 nm (1064 nm)

[0088] In the above example, the center wavelengths of the bandpass filters 32 to 35 and 37 other than the bandpass filters 31 and 36 are identical to the central emission wavelength of the corresponding LED 14d. The differences between the center wavelengths of the bandpass filters 31 and 36 and the central emission wavelength of the corresponding LED 14d are 5 nm and 14 nm, respectively. With wavelength differences of this magnitude (e.g., 20 nm or less), no significant difference in the light intensity of each central wavelength of the bandpass filters occurs in the emission spectrum of a typical LED. Because typical LEDs have narrow emission spectra, it is preferable to select an LED having a central emission wavelength corresponding to the central wavelength of the bandpass filter. On the other hand, if a low-power, high-brightness LED with a broad emission spectrum is selected as the LED 14d, it is not necessary to select an LED having a central emission wavelength close to the central wavelength of the bandpass filter.

[0089] 9 is a schematic assembly diagram of the filter unit F. The filter holder 20 is formed in a disk shape centered on the axis CLf, and on the front surface 20a, six recesses 20b1 to 20b6 are formed at an angular pitch of 60° around the axis CLf, and are centered on a circle of diameter φc centered on the axis CLf, as well as a central recess 20b7. The recesses 20b1 to 20b7 are rectangular recesses corresponding to the external shape of the bandpass filter 22.

[0090] The holder cover 21 has a disk-shaped base 21a and four claws 21c that extend rearward from the periphery of the base 21a and engage with the filter holder 20. The claws 21c are spaced apart at an angular interval of 90° in the circumferential direction. Rectangular through-holes 21b1 to 21b7 are formed in the base 21a at positions that are radially centered on a circle having a diameter φd and an angular interval of 60° about the axis CLf. In addition, a circular through-hole 21b7 is formed in the center.

[0091] The diameter φd is set equal to the diameter φc.

[0092] The holder cover 21 can be integrated with the filter holder 20 by bringing it close to the filter holder 20 from the front side (see arrow DRb) and engaging the claws 21c with the engaging portions 20d provided on the filter holder 20. That is, the bandpass filters 31 to 37 are placed in the recesses 20b1 to 20b7 of the filter holder 20, respectively, and the holder cover 21 is engaged with the filter holder 20 from the front side, thereby forming the filter unit F that holds the bandpass filters 31 to 37.

[0093] 10 is a rear view of the filter unit F. Pockets 20e1 to 20e7, which are rectangular openings carved forward, are formed on the rear surface 20f of the filter holder 20 at positions corresponding to the recesses 20b1 to 20b7 formed on the front surface 20a. The recesses 20b1 to 20b7 and the pockets 20e1 to 20e7 are connected in the front-to-rear direction by rectangular through-holes 20c1 to 20c7, respectively. The radial centers of the through-holes 20c1 to 20c6 are located on a circle with a diameter φc.

[0094] Next, the light guide member 11 will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a perspective view of the light guide member 11 as seen obliquely from the front. Fig. 12 is a half cross-sectional view (a) and a rear view (b) of the light guide member 11. Fig. 12(a) is a half cross-sectional view taken along the S12-S12 line in the rear view (b).

[0095] The light guide member 11 is formed as a transparent member having optical transparency, and is made of, for example, a transparent polycarbonate resin having optical transparency.

[0096] The light guide member 11 is formed long in the front-rear direction. The light guide member 11 has a front end surface 11a1 as one longitudinal end face, and includes a cylindrical front protruding portion 11a having a diameter Df centered on an axis CL11 extending in the front-rear direction, a cylindrical intermediate tube portion 11b having a diameter Dg larger than the diameter Df, and a truncated cone portion 11c connected to the rear side of the intermediate tube portion 11b and gradually increasing in diameter toward the rear.

[0097] Furthermore, the light-guiding member 11 includes a rear tubular portion 11e at the rear end of the truncated cone portion 11c, which becomes cylindrical with a diameter Dh after passing through a step portion 11d that expands in diameter in a direction perpendicular to the axis CL11, and a leg portion 11f having seven light-guiding protrusions 11f1 to 11f7 that are independently formed and protrude rearward from the rear surface 11e1 of the rear tubular portion 11e.

[0098] The six light-guiding protrusions 11f1 to 11f6 are formed on a circle with a diameter φe at equal angular intervals (angular pitch of 60°) centered on the axis CL11. The remaining light-guiding protrusion 11f7 is formed in a cylindrical shape at the center.

[0099] Light-guiding protrusions 11f1 to 11f6 have engagement portions 11f1a to 11f6a at their rear end portions, which are contracted at stepped portions 11f1b to 11f6b and then protrude further rearward. Light-guiding protrusion 11f7 has engagement portion 11f7a at its rear end portion, which is contracted at stepped portion 11f7b and then protrudes further rearward. The positions of stepped portions 11f1b to 11f7b of engagement portions 11f1a to 11f7a and the front-to-rear positions of their tip surfaces are all the same.

[0100] The engagement portions 11f1a to 11f7a have stepped portions that abut against the front surface of the base portion 21a of the holder cover 21, and are adapted to enter the through holes 21b1 to 21b7 of the holder cover 21 in the filter unit F from the front side, respectively.

[0101] The assembly state of the filter unit F and the light guiding member 11 to the sensor substrate 13 will be described with reference to Fig. 13. As described above, this assembly is performed by fixing the stage base 16 with tapping screws Na, so that the filter unit F and the light guiding member 11 are sandwiched between the stage base 16 and the sensor substrate 13 in the front-to-rear direction.

[0102] Fig. 13 is a schematic cross-sectional view of the SB portion in Fig. 3. That is, it shows the assembled state of the photosensor 13c7 of the sensor board 13, the filter unit F, and the light-guiding protrusion 11f7 of the light-guiding member 11. The same applies to the other photosensors 13c1 to 13c6, and they will be described as representative ones.

[0103] As shown in Figure 13, the rear surface 20f of the filter holder 20 abuts against the front surface 13a of the sensor board 13. The photosensor 13c7 mounted on the front surface 13a enters a pocket portion 20e7 formed in the filter holder 20 of the filter unit F. A bandpass filter 37 is inserted into a recess 20b7 of the filter holder 20. Forward movement of the bandpass filter 37 is held down and restricted by a through-hole 21b7 of the holder cover 21, which is formed smaller than the outer shape of the bandpass filter 37. The bandpass filter 37 is located in front of and facing the photosensor 13c7.

[0104] The engaging portion 11f7a of the light-guiding protrusion 11f7 of the light-guiding member 11 enters and engages with the through-hole 21b7 of the holder cover 21 from the front side. The stepped portion 11f7b of the light-guiding protrusion 11f7 abuts against the front surface 21a1 of the base 21a of the holder cover 21.

[0105] The operation of the saccharimeter 51, the configuration of which has been described above, is controlled by the control unit CT. Fig. 14 is a diagram illustrating the configuration of the control system in the saccharimeter 51. The control unit CT has a central processing unit (CPU) CT1, a correction unit CT2, a light intensity processing unit CT3, a display control unit CT4, a light quantity control unit CT5 that controls the amount of light emitted by the LED group 14dG, and a memory unit CT6.

[0106] The external dimensions of the saccharimeter 51, namely, length L and width W (see FIG. 2), and thickness H (see FIG. 3), are set, for example, as follows: L = 113 mm, W = 63 mm, H = 43 mm. The external diameter φf of the measuring part K1 (see FIG. 3) is set, for example, to 48 mm.

[0107] Next, the operation of the saccharometer 51 having the above-described configuration will be described. First, the operator brings the measuring unit K1 of the saccharometer 51 into contact with the fruit or vegetable AS to be measured. Specifically, when measuring harvested fruit or vegetable AS, for example, as shown in Figure 15, the operator places the saccharometer 51 on a table such as a desk 91 with the outer contact portion 7 and inner contact portion 9 of the measuring unit K1 facing upward, and then places the fruit or vegetable AS on the measuring unit K1 to perform measurement. When measuring fruit or vegetable AS with a dent in this measurement mode, it is recommended to place a part of the fruit or vegetable AS that is not dented or has only a small dent on the measuring unit K1.

[0108] When measuring unharvested fruits and vegetables AS or heavy or large fruits and vegetables AS, as shown in FIG. 16 , the operator grasps the grip portion K2 and brings the measuring portion K1 into contact with the surface of the fruits and vegetables AS to measure. The measuring portion K1 protrudes from the grip portion K2. This prevents the fruits and vegetables AS from being unstable when the saccharimeter 51 is placed on a table and the fruits and vegetables AS is placed on the measuring portion K1 due to the convex portions of the uneven surface of the fruits and vegetables AS coming into contact with the grip portion K2. Furthermore, when the saccharimeter 51 is held and the measuring portion K1 is placed against the fruits and vegetables AS to measure them, the fruits and vegetables AS are less likely to come into contact with the operator's fingers. This reduces the possibility of gaps occurring between the outer contact portion 7 and the inner contact portion 9 and the fruits and vegetables AS, which would allow external light to enter and reduce measurement accuracy.

[0109] Next, the specific measurement operation of the saccharimeter 51 will be described mainly with reference to Fig. 14 and Fig. 17. Fig. 17 is a schematic diagram for explaining the light path when measuring sugar content with the saccharimeter 51, and uses the measuring unit K1 portion of Fig. 3. In Fig. 17, the light-guiding member 11 shown in cross section is not hatched to avoid complicating the drawing.

[0110] First, the diameter φb (see also FIG. 6 ) of the LEDs 14d spaced apart in the circumferential direction is set equal to the diameter φb7 (see FIG. 7 ) of the center of the relay lens 18 and the diameter Dc (see FIG. 8 ) of the imaginary reference circle P1 of the ring lens 8. The diameter φb (= φb7 = Dc) is set to, for example, 38 mm.

[0111] (1) With the saccharimeter 51 powered on, the user places the fruit or vegetable AS to be measured on the outer contact portion 7 and inner contact portion 9 of the measuring unit K1 of the saccharimeter 51, or presses the measuring unit K1 of the saccharimeter 51 against the fruit or vegetable AS to be measured so that it is in close contact with the fruit or vegetable AS (fruit or vegetable contact step). The fruit or vegetable AS is, for example, a fruit or vegetable, such as a tomato, apple, or watermelon. The weight of the fruit or vegetable AS or the pressing force of the user causes the outer contact portion 7 and inner contact portion 9 to be compressed and come into close contact with the surface of the fruit or vegetable AS.

[0112] (2) The user presses the push button 6 to turn on the switch 13d, which sends a signal indicating that the switch 13d is now on to the central processing unit CT1 of the control unit CT.

[0113] (3) When the central processing unit CT1 determines that the switch 13d has been turned on, it instructs the light intensity control unit CT5 to cause the LED group 14dG to emit light (light emission step). The light intensity control unit CT5 controls the LED group 14dG to emit light LT at least two different intensities (multi-stage light emission step). That is, the light intensity control unit CT5 controls the LED group 14dG to emit a first intensity of light LT, then controls the LED group 14dG to emit a second intensity of light LT different from the first intensity, and further controls the LED group 14dG to emit a third intensity of light LT different from the first and second intensities, as necessary.

[0114] Furthermore, the increased drive current and VF associated with an increase in the light output (higher brightness) of the LED group 14dG necessitate the supply of greater power. Therefore, for example, a method can be adopted in which an electrolytic capacitor is precharged before power is supplied to the LED 14d. Without a current-limiting resistor, an increased battery load would cause malfunction, preventing the supply of charge to the electrolytic capacitor. Therefore, charge is supplied to the electrolytic capacitor via a current-limiting resistor, but this would require a long charging time and slow measurement times. Therefore, as shown in Figure 24, a current-limiting resistor can be used to suppress the charge current to the electrolytic capacitor, limiting the current even during light emission, while supplying current from both the electrolytic capacitor and the power supply (DC / DC converter). This not only shortens measurement time, but also reduces the capacitance of the electrolytic capacitor and prevents malfunctions due to increased battery load.

[0115] In addition, changing the light emission time is also effective in making the LED group 14dG emit light at a higher brightness. For example, by setting the light emission time to 2.5 ms, the current value can be increased (300 mA), thereby achieving higher brightness.

[0116] Light LT emitted upward from each LED 14d in the LED group 14dG passes through the relay lens 18 and reaches the ring lens 8. The space Vb, which serves as the path of the light LT from the LED 14d to the ring lens 8, is blocked radially outward by the inner surface 2b1 of the stage portion 2b of the lid body 2 and radially inward by the stage base 16 and the outer peripheral surface 10c1 of the stage base 10. In other words, the space Vb is blocked radially and is open only on the axial side. The tip portion on the axial side is blocked by the ring lens 8. This prevents light emitted from the LED group 14dG from reaching the fruit or vegetable AS without passing through the ring lens 8.

[0117] 17, the main optical axis LTa of the light LT emitted from the LED 14d is shown by a solid line. When the main optical axis LTa passes through the center of the relay lens 18 and reaches the light incident surface 8b1 of the ring lens 8, the light is emitted forward from the light exit surface 8b2 at an exit angle θb that depends on the inclination angle θa and the refractive index of the material of the ring lens 8, because the light incident surface 8b1 is tilted forward as it moves radially outward as shown in FIG.

[0118] The angle θb of the emitted light is preferably set so that 0<θb<45°. Furthermore, the angle θb is preferably set to a larger value as the diameter Dc of the imaginary reference circle P1 of the ring lens 8 increases. This makes it easier for light LTR (described below) that enters the fruit or vegetable AS to be focused at the center inside the fruit or vegetable AS. When the diameter Dc is approximately 40 mm, as in the case of the saccharometer 51, the angle θb is preferably around 20°.

[0119] The light emitted forward from the light-emitting surface 8b2 becomes an annular light LTR that includes the main optical axis LTa and has a width in the radial direction. In other words, in Fig. 17, the light path LTb from the LED 14d of the light that is deflected to the innermost side from the ring lens 8 is shown by a dashed line. The light path LTc from the LED 14d of the light that is deflected to the outermost side is shown by a dashed-dotted line.

[0120] 17 shows the intensity characteristic Q of the annular light LTR at a position P2 in the front-rear direction after emission. From these, it can be seen that the radial intensity characteristic Q of the annular light LTR emitted from the ring lens 8 has a peak Qp that rises sharply at the main optical axis LTa, and the intensity decreases rapidly toward the inner diameter side and the outer diameter side.

[0121] On the other hand, the intensity characteristics of the annular light LTR in the circumferential direction are approximately constant. That is, although the multiple LEDs 14d are arranged at intervals in the circumferential direction, the intensity distribution of the annular light LTR in the circumferential direction is averaged so that the intensity is approximately the same when the multiple LEDs 14d are simultaneously turned on, due to the light emission characteristics of each LED 14d that spread in the circumferential direction and the slight internal diffusion that occurs in the relay lens 18 and the ring lens 8.

[0122] As described above, the main optical axis LTa of the annular light LTR emitted from the ring lens 8 is deflected at the angle θb in a direction approaching the light-receiving axis CLT (the light-receiving axis CLT coincides with the axis of the light-guiding member 11). In other words, the annular light LTR emitted from the ring lens 8 travels in a manner that reduces its diameter after emitting from the ring lens 8.

[0123] A front end surface 11 a 1 of the light guide member 11 is exposed at the center portion inside the inner contact portion 9 .

[0124] (4) The light LTR emitted from the ring lens 8 is irradiated in a ring shape onto the surface of the fruit or vegetable AS and enters the interior of the fruit or vegetable AS.

[0125] (5) The light LTR that enters the interior of the fruit or vegetable AS is diffused and absorbed with characteristics corresponding to the state of the fruit or vegetable AS, with some of the light exiting to the outside. (6) Some of the light that exits to the outside enters the interior of the light-guiding member 11 from the front end surface 11a1 of the light-guiding member 11, which is exposed to the outside. The light that enters the interior of the light-guiding member 11 is light that exits from the LED group 14dG, passes through the interior of the fruit or vegetable AS, and returns, and is therefore referred to as returned light LTd hereinafter. The returned light LTd travels inside the light-guiding member 11 and is guided to the light-guiding protrusions 11f1 to 11f7 of the leg portion 11f.

[0126] In this way, the returned light LTd is light that enters the fruit or vegetable AS in a circular shape, is reflected inside, and is emitted to the outside from the center of the circular entry point. Therefore, even if there is a deviation in absorbance from part to part in the internal tissue of the fruit or vegetable AS, this deviation becomes averaged light.

[0127] Furthermore, the light LTR incident on the fruit or vegetable AS is annular and deflected in a direction approaching the light-receiving axis CLT, so that the proportion of the light diffused inside the fruit or vegetable AS that is incident on the front end surface 11a1 at the lower center is higher than when the light is not deflected (angle θb = 0).

[0128] As a result, in the saccharimeter 51, the return light LTd can be obtained with high efficiency compared to the light emitted from the LED 14d, and even if there is a bias in the absorbance of the internal tissue of the fruit or vegetable AS, the light obtained is less affected by the bias and reflects the absorbance of the fruit or vegetable AS with higher accuracy.

[0129] (7) The return light LTd guided by the light-guiding protrusions 11f1 to 11f7 of the leg portion 11f is homogeneous light with no bias in characteristics, and is emitted as protrusion-emitted light LTe (LTe1 to LTe7) from the rear end faces 11fb of the engagement portions 11f1a to 11f7a toward the bandpass filters 31 to 37. The rear end faces 11fb are the other end faces of the light-guiding member 11 relative to the front end face 11a1, which is one longitudinal end face.

[0130] (8) The protrusion-emitted light LTe emitted from the engagement portions 11f1a to 11f7a is split by the bandpass filters 31 to 37 according to their respective spectral characteristics and enters the photosensors 13c1 to 13c7 (light-receiving step). (9) The photosensors 13c1 to 13c7 detect intensities Q1 to Q7, which are the intensities of the received light, and send them to the light intensity processing unit CT3 (see FIG. 14). That is, the intensities Q1 to Q7 obtained from the photosensors 13c1 to 13c7 are the spectral intensities of the center wavelengths λ1 to λ7 of the bandpass filters 31 to 37, respectively.

[0131] (10) The light intensity processing unit CT3 calculates the absorbance at each of the wavelengths λ1 to λ7 from the intensities Q1 to Q7 using a known calculation method, and calculates the Brix value Y from each absorbance (light intensity processing step). A specific example of the calculation method is as follows.

[0132] Generally, the absorbance A at a wavelength λ is expressed by the formula (1): ０ (λ) is the intensity of light of wavelength λ that enters the reference object, I Ｓ (λ) is the intensity of light of wavelength λ emitted from the object to be measured. A = log [I ０ (λ) / I Ｓ (λ) = log I ０ (λ)-log I Ｓ (λ) ・・・・・・・・・・・・(1)

[0133] Of the seven wavelengths λ1 to λ7, the wavelength λ6 is set as the reference wavelength, and the absorbance differences A1 to A5 and A7 for the other six wavelengths λ1 to λ5 and λ7 are calculated using the following equations (2-1) to (2-6).

[0134] Based on these formulas, the Brix value Y is calculated using the following formula (3). ... (3) where PL0 to PL8 are coefficients previously calculated by multiple regression analysis using absorbance data of a plurality of objects to be measured (fruits and vegetables AS). １ is the surface temperature of the object (fruit or vegetable AS) measured by the temperature sensor 12, and temperature T2 is the temperature corresponding to the housing K measured by the temperature sensor 12.

[0135] In addition, the light intensity processing unit CT3 determines the absorbance of each of the wavelengths λ1 to λ7 each time the amount of light emitted from the LED group 14dG changes, calculates the Brix value Y from each absorbance, and corresponds the amount of light emitted from the LED group 14dG to the depth of the fruit or vegetable AS, thereby determining the distribution of the Brix value Y in the depth direction of the fruit or vegetable AS.

[0136] In addition, the light intensity processing unit CT3 can obtain a calibration curve (standard curve) for the sugar content of the fruit or vegetable AS from the absorbance of light at least two different light intensities and the Brix value at the depth of the fruit or vegetable AS corresponding to the light intensities.

[0137] As an example, we will explain the method and process for determining a sugar content calibration curve by dividing a watermelon into four equal parts in the depth direction, taking into account the difference in sugar content between the inside and outside of the watermelon, using a watermelon as the fruit or vegetable AS.

[0138] Figure 21 shows a watermelon 100 cut into four equal parts (sections A to D) from the skin to the center. The Brix values ​​of sections A to D of the watermelon 100 shown in Figure 21 were measured at multiple locations, and the average values ​​are summarized in Table 1 below. In Table 1, "near the top" refers to the top of the watermelon 100 when it is still in its ripe form before cutting, "near the center" refers to the periphery of the center of the watermelon 100 when it is still in its ripe form before cutting, and "near the bottom" refers to the bottom of the watermelon 100 when it is still in its ripe form before cutting. As shown in Table 1, when the depth direction is constant, the sugar content (Brix value) is almost the same, and the sugar content drops sharply toward the skin (area D). Furthermore, when sugar content information is constant at depth, the sugar content range obtained for a single watermelon 100 is small. Therefore, when the light intensity of the LED group 14dG is constant, that is, when the depth direction is constant, Brix values ​​are measured and multiple regression analysis is performed, the results are as shown in Figure 22, with a coefficient of determination R2 of 0.3, indicating that the results are concentrated at specific locations.

[0139] On the other hand, when a multiple regression analysis was performed by combining the light intensity of the LED group 14dG with sugar content information in the depth direction, the results were as shown in Figure 23. The light intensity of the LED group 14dG and the corresponding depth were combined under the following conditions: Light-emitting current: 50 mA, Depth: 2-4 cm, Light-emitting current: 250 mA, Depth: 6-8 cm. A multiple regression analysis was performed using the light intensity data obtained under the above conditions and the Brix values ​​at each depth, resulting in a multiple determination coefficient R2 of 0.79. These results suggest that by varying the light intensity and citing sugar content information in the depth direction, it is possible to obtain a sufficient sugar content range using the characteristics of fruits and vegetables that have sugar content distributions between the inside and outside, and to determine a sugar content calibration curve.

[0140] 14, the control unit CT includes a correction unit CT2. The correction unit CT2 controls the light intensity of the LED group 14dG based on light intensity information JL from the FB photosensor group 14eG and temperature information JT from the temperature sensor 12.

[0141] A common characteristic of LEDs is that the amount of light emitted changes with increasing temperature. The same is true for the LED 14d. The saccharimeter 51 includes the FB photosensor group 14eG, the temperature sensor 12, and the correction unit CT2, which stabilizes the amount of light emitted by the multiple LEDs 14d while suppressing fluctuations over time. This improves the measurement accuracy of the saccharimeter 51. The control unit CT is not limited to controlling all of the LEDs 14d in the LED group 14dG to emit light simultaneously. The control unit CT may also sequentially illuminate the corresponding LEDs 14d in time series for each of the six preset wavelengths or in circumferential order, measuring the received light intensity with the photosensors 13c1-13c7 each time. Because illuminating the LED group 14dG simultaneously increases power consumption even for a short period of time, the latter method of sequentially illuminating the multiple LEDs 14d in time series is preferable when reducing the load on the power supply is necessary.

[0142] The sugar content meter 51, which is a non-destructive measuring device for fruits and vegetables, described above, uses multiple LEDs 14d as the light source for irradiating the fruits and vegetables AS. This allows the sugar content meter 51 to have low light source power consumption and low installation space, and can be made compact enough to hold the casing K in one hand. This makes it easy to measure fruits and vegetables while they are growing before they are harvested.

[0143] The saccharimeter 51 has multiple LEDs 14d arranged in a circumferential direction, and the light emitted from each LED 14d is directed toward the fruit or vegetable AS through an annular ring lens 8. This allows the light to be incident on the fruit or vegetable AS as a circular beam. As a result, even if there is a bias in the light absorption of the internal tissue of the fruit or vegetable AS, the saccharimeter is less susceptible to the influence of this bias, and an averaged light output is obtained, resulting in measurement results that properly reflect the condition of the fruit or vegetable AS.

[0144] The ring lens 8 has optical properties that deflect the light incident from the LED 14d toward the center of the ring lens 8 and output it. As a result, the intensity of the returned light that is reflected inside the fruit or vegetable AS and output toward the center of the ring lens 8 is high, and the utilization efficiency of the light emitted by the LED 14d is high. As a result, the saccharimeter 51 can reduce power consumption by suppressing the light emission intensity for fruit or vegetable with high light transmittance, making it suitable for battery-powered handheld devices. In addition, sufficient returned light can be easily obtained for measurement even for fruit or vegetable with low light transmittance due to thick skin, etc., and the saccharimeter 51 can be used to measure a wide variety of fruit or vegetable, making it highly versatile.

[0145] The saccharimeter 51 has an annular relay lens 18 located along the light emission path from the LED 14d to the ring lens 8, which focuses the light from the LED 14d onto the ring lens 8. By providing the relay lens 18, the light emitted from the LED 14d can be more efficiently guided to the ring lens 8 and irradiated onto the fruit or vegetable AS. This also enables the saccharimeter 51 to consume less power, making it suitable for handheld use. Furthermore, the saccharimeter 51 can more easily obtain sufficient returned light for measurement even for fruit or vegetable with low light transmittance due to thick skin, etc., and is therefore highly versatile as it can be used to measure a wide variety of fruit or vegetable.

[0146] Furthermore, by providing the relay lens 18, the light path distance between the LED 14d and the ring lens 8 can be increased. This allows the ring lens 8 to be positioned closer to the fruit or vegetable AS. This allows the emitted light beam from the ring lens 8 to be irradiated onto the fruit or vegetable AS in a sufficiently narrow ring, increasing the incident light intensity per unit area. This further improves the utilization efficiency of the emitted light from the LED 14d. Furthermore, the influence of incident light from outside can be reduced to a level that is virtually negligible. This allows the saccharimeter 51 to perform highly accurate measurements.

[0147] Furthermore, by positioning the relay lens 18, the light path distance between the LED 14d and the ring lens 8 can be lengthened, allowing the stage on which the fruit or vegetable AS is placed to be sufficiently protruded relative to the grip portion for manual holding. This prevents the fruit or vegetable AS from coming into contact with the fingers holding the grip portion K2, even when measuring the fruit or vegetable AS using the grip portion K2, as shown in FIG. 16 , making the measurement comfortable, easy, and efficient. Furthermore, slight misalignment in the mounting position of the LEDs 14d on the base substrate 14 due to manufacturing variations results in slight differences in the light emission angle of each LED 14d. Furthermore, when using packaged composite LEDs such as the previously described three-wavelength composite LED, the light emission position varies slightly in the radial direction for each emission center wavelength. In contrast, the saccharimeter 51 uses the relay lens 18 as a reduction optical system lens between the LED 14d and the ring lens 8. That is, relay lens 18 creates a reduced light source system from the light emitted from the annular light source (plurality of LEDs 14d arranged in a ring) and inputs it into ring lens 8. Then, ring lens 8 irradiates the reduced light source system onto the fruit or vegetable as an annular beam. Therefore, even if the light output angle is shifted due to a slight misalignment in the mounting position of LED 14d or a slight misalignment in the radial direction of the light output position when LED 14d is a composite LED, the effect of this misalignment on the measurement is small. This allows saccharimeter 51 to perform highly accurate measurements.

[0148] The saccharimeter 51 has an inner contact portion 9 and an outer contact portion 7 at radially inner and outer positions relative to the ring lens 8. As a result, as shown in Figure 17, when the fruit or vegetable AS is placed on the measurement part K1, a closed space Vc is formed by the ring lens 8, the fruit or vegetable AS, the inner contact portion 9, and the outer contact portion 7.

[0149] That is, on the outer diameter side of the ring lens 8, the gap between the stage 2b and the fruit or vegetable AS is blocked by the outer abutment portion 7. On the inner diameter side, the gap between the stage 2b and the fruit or vegetable AS is blocked by the inner abutment portion 9. This prevents the annular light LTR emitted from the ring lens 8 from reaching the front end surface 11a1 of the light-guiding member 11, and also prevents it from leaking outside on the outer diameter side. Therefore, the returned light LTd used for measurement in the sugar content meter 51 is always light that has entered from the fruit or vegetable AS, improving measurement accuracy. Furthermore, because the light LTR does not leak outside, the utilization efficiency of the light emitted by the LED 14d is improved.

[0150] The saccharimeter 51 is equipped with a light-guiding member 11 whose longitudinal direction is the direction of the light-receiving axis CLT. One longitudinal end of the light-guiding member 11 serves as a front end surface 11a1 for the return light LTd, and the other end serves as a light-emitting surface for the return light LTd directed toward the photosensor 13c. As a result, the return light LTd entering from the light-incident surface is guided to the light-emitting surface while being reflected internally within the light-guiding member 11 over a relatively long distance, so that the light that reaches the light-emitting surface is uniform in quality regardless of the location on the light-emitting surface it reaches. Therefore, the saccharimeter 51 is able to perform measurements with high precision without bias in the characteristics of the light entering each of the photosensors 13c1 to 13c7.

[0151] With this configuration, in terms of positional relationship in the front-to-rear direction within the housing K, the photosensors 13c1 to 13c7 are disposed further rearward than the LED group 14dG that serves as the light source, that is, at positions farther from the outer contact portion 7 and the inner contact portion 9. Therefore, the sensor board 13 on which the photosensors 13c1 to 13c7 are mounted is disposed near the rear surface 1a of the box body 1, and the light-guiding member 11 is disposed so as to pass through the hole 14g of the base board 14.

[0152] Next, we will explain the calibration of the saccharimeter 51. In order to maintain the measurement accuracy of the saccharimeter 51 and to more reliably obtain consistency with other devices and with past measurement results, it is desirable to calibrate the saccharimeter 51 periodically.

[0153] A standard lid 52 is provided for calibration of the saccharimeter 51. Figure 18 is a half cross-sectional view for explaining the use of the standard lid 52, showing the standard lid 52 and a part of the measuring unit K1 in the housing K.

[0154] The standard lid 52 has a cylindrical shape that covers the tip opening of the measuring part K1, and is used by placing it over the stage part 2b of the lid 2. The standard lid 52 has a pot-shaped base 52a and a reflector 52b attached to the inside of the base.

[0155] 18, the reflector 52b has a recess 52b1 in the center that is recessed forward in a circular shape, and a curved surface portion 52b2 that has an annular curved surface that slopes forward radially outward and is convex toward the rear. The recess 52b1 faces the front end surface 11a1 of the light-guiding member 11 in the front-rear direction, and the curved surface portion 52b2 faces the ring lens 8 at least in the light output direction (the direction of the main optical axis LTa shown in FIG. 17).

[0156] The reflector 52b is solid and made of a white material. The white material is, for example, a fluororesin. The reflector 52b functions as a standard substitute for the fruit or vegetable being measured. Specifically, the annular light LTR (see FIG. 17) emitted from the ring lens 8 is irradiated onto the curved surface 52b2 of the reflector 52b, and a portion of the light enters the interior. The light that enters the interior of the reflector 52b diffuses internally, and a portion of the light exits through the recess 52b1 and enters the light-guiding member 11 as return light LTd. The light intensity processing unit CT3 and the central processing unit CT1 perform calibration so that the measurement results based on this return light LTd correspond to the quasi-measured values ​​using the standard cover 52, which are preset and stored in the memory unit CT6.

[0157] Measurement with the standard lid 52 can be performed simply by placing the standard lid 52 over the stage 2b, as the standard lid 52 is small and easy to carry. This makes calibration easy, and correlation between one saccharimeter 51 and another can be easily ensured.

[0158] The nondestructive measuring device and method according to the present invention, as described above, enable the acquisition of multiple depth-wise information on fruits and vegetables, as well as internal information on fruits and vegetables with thick skin. If the sugar content of a certain fruit or vegetable is known, simply measuring the sugar content of the juice obtained by squeezing the fruit or vegetable is sufficient. However, fruit and vegetable producers and consumers have also had needs for, for example, knowing the sugar content of the outer (skin) and inner (center) portions of a certain fruit or vegetable. Furthermore, fruit and vegetable producers, whose commercial value is largely determined by sweetness, have expressed a desire to numerically demonstrate the appeal of their products, namely, that their fruit is sweet all the way to the skin. The present invention addresses these needs and provides a nondestructive measuring device and method that can three-dimensionally determine the sugar content distribution within a fruit or vegetable by varying the light intensity and measurement location. Furthermore, conventional nondestructive measuring devices and methods require the preparation of a large number of fruit or vegetable samples when calculating a sugar content calibration curve for a certain fruit or vegetable. However, some fruits and vegetables, such as watermelons and melons, have high unit prices, and when calculating a sugar content calibration curve for such expensive fruits and vegetables, it is costly to prepare a large number of measurement samples. According to the present invention, it is possible to provide a non-destructive measurement device and a non-destructive measurement method that can calculate a sugar content calibration curve for a certain fruit and vegetable based on a small number of measurement samples without requiring a large number of measurement samples.

[0159] The embodiments of the present invention are not limited to the above-described configurations and procedures, and may be modified within the scope of the present invention.

[0160] The sugar content meter 51 of the embodiment may be modified to have a structure that actively diffuses the returning light by providing a diffusion section WB that diffuses the returning light along the path of the returning light that passes through the fruit or vegetable AS, passes through the light guiding member 11, and exits from the rear end face 11fb. That is, the diffusion section WB may be provided between the portion of the surface of the fruit or vegetable AS that is in contact with the inner abutment section 9 and is surrounded by the annular inner abutment section 9, and the rear end face 11fb of the light guiding member 11. These modifications will be described below as Modifications 1 to 3.

[0161] (Variation 1) FIG. 19 is a partial cross-sectional view illustrating Variation 1, corresponding to the light-guiding member 11 and its vicinity in FIG. 17 . Variation 1 differs from the sugar content meter 51 of the embodiment in that a diffuser 41 is disposed in front of the front end surface 11 a 1 of the light-guiding member 11. Specifically, the diffuser 41 is attached to the stage base 10 with adhesive or double-sided tape, for example, so as to cover the entire front end surface 11 a 1 when viewed from the front. The diffuser 41 diffuses light incident on the front surface 41 a and emits it from the rear surface 41 b. The type of diffuser 41 is not limited. For example, well-known diffusers can be used, such as a diffuser formed into a plate shape by dispersing a diffusing agent in a transparent resin, or a diffuser having microlenses formed on at least one surface of a transparent resin plate.

[0162] 19 , in the first modification, the return light LTd is diffused and enters the light-guiding member 11 from the front end face 11a1 by a diffuser 41 disposed in front of the front end face 11a1 of the light-guiding member 11. As a result, the return light LTd that passes through the fruit or vegetable AS and enters the light-guiding member 11 is actively diffused by the diffuser 41 and is more highly homogenized before entering the light-guiding member 11. The homogenized return light LTd then passes through the light-guiding member 11, passes through the bandpass filters 31 to 37, and enters the photosensors 13c1 to 13c7. This increases the correlation coefficient between the absorbance and the Brix value Y, improving measurement accuracy by, for example, reducing variations in the absorbance and Brix value Y when the same fruit or vegetable AS is repeatedly measured.

[0163] (Variation 2) In Variation 2, a light-guiding member 11W is used instead of the light-guiding member 11 used in the sugar content meter 51 of the embodiment. Figure 20 is a half cross-sectional view of the light-guiding member 11W. More specifically, the light-guiding member 11W is configured such that a portion of the light-guiding member 11 in the direction of the axis CL11 is replaced with a diffusing member 42. Here, an example will be described in which the light-guiding member 11W has a diffusing portion WB between the front end face 11a1 and the rear face 11e1 of the rear tubular portion 11e (see Figure 12).

[0164] More specifically, the light guide member 11W has, as the diffusion section WB, a diffusion member 42 with a thickness Lb, whose rear end is located a distance La rearward from the front end face 11a1. The diffusion member 42 is formed, for example, by dispersing a diffusing agent in a transparent resin.

[0165] In Modification 2, return light LTd (not shown in FIG. 20 ) incident on the light-guiding member 11W from the front end face 11a1 enters the front end of the diffusing member 42 and is diffused and emitted rearward. The maximum value of the distance La can be the distance Lc from the front end face 11a1 to the rear surface 11e1 of the rear tube portion 11e. That is, the distance La can be set within the range from the thickness Lb to the distance Lc. Furthermore, the thickness of the diffusing member 42 can be set up to the distance La.

[0166] As a result, the return light LTd that passes through the fruit or vegetable AS and enters light-guiding member 11W is actively diffused and more highly homogenized as it passes through diffusing member 42 provided within light-guiding member 11W. The homogenized return light LTd then exits light-guiding member 11W, passes through bandpass filters 31-37, and enters photosensors 13c1-13c7. This increases the correlation coefficient between absorbance and Brix value Y, improving measurement accuracy by, for example, reducing variations in absorbance and Brix value Y when the same fruit or vegetable AS is repeatedly measured.

[0167] Furthermore, as a third modification, the light-guiding member 11 used in the sugar content meter 51 of the embodiment may be replaced with a light-guiding member 11WA of the same shape but made of a resin with a diffusing agent dispersed therein (see FIG. 12 for the reference numerals). In this case, the return light LTd incident on the light-guiding member 11WA is actively diffused and homogenized as it travels through the light-guiding member 11. The homogenized return light LTd then exits the light-guiding member 11WA, passes through the bandpass filters 31-37, and enters the photosensors 13c1-13c7. This increases the correlation coefficient between the absorbance and the Brix value Y, thereby improving measurement accuracy by, for example, reducing the variation in the absorbance and Brix value Y when the same fruit or vegetable AS is repeatedly measured.

[0168] Modifications 1 to 3 can be freely combined within the range of possible combinations.

[0169] In the embodiment and modifications 1 to 3, the relay lens 18 and the ring lens 8 may be integrated into a single optical element. The relay lens 18 or the ring lens 8 may be formed of multiple optical elements. That is, the light from the LED 14d may be emitted in a ring shape from the tip of the measuring part K1, and the light may be deflected at an angle θb in a direction approaching the light-receiving axis CLT by a single optical element or an optical system formed of multiple optical elements.

[0170] In the embodiment, the light source group 14dG uses six LEDs 14d having six of the seven center wavelengths λ1 to λ7 as its central emission wavelengths. Of course, this is not limiting. If it is determined that light of multiple center wavelengths selected as a bandpass filter based on the emission spectrum of an LED 14d having a single central emission wavelength or a broad emission spectrum can be obtained with the light intensity required for measurement, the LED 14d may be shared for multiple center wavelengths. That is, q LEDs having q (1≦q≦m) central emission wavelengths may be used for m (an integer of 2 or greater) wavelengths (λ1 to λm) selected as the central wavelengths of the bandpass filter. In this case, at least m photosensors 13c are provided.

[0171] The light source is not limited to an LED, but may be any other light emitting device. Furthermore, when changing the amount of light emitted from the light source, the amount of light need not be changed instantaneously, but may be changed gradually over time (sweep).

[0172] DESCRIPTION OF SYMBOLS 1 Box body 1a Rear surface 1a1 Abutment portion 1b Battery box 1b1 Entrance / exit 1c Bottom surface 1h Side wall portion 1k Base portion 2 Lid body 2a Front surface 2a1 Front surface 2b Stage portion 2b1 Inner surface 2c Bank portion 3 Display portion 4 Switch portion 4a Switch pressing portion 5 Battery cover 6 Push button 7 Outer abutment portion 7a Front end surface 8 Ring lens 8a Annular base portion 8a1 Hole 8b Deflection portion 8b1 Light incident surface 8b1a, 8b1b Edge portion 8b2 Light exit surface 8b2a, 8b2b Edge portion 8c Flange portion 8c1 Flat portion 8c2 Shelf portion 8r Front end ridge portion 9 DESCRIPTION OF SYMBOLS 10a Inner contact portion, 9a Notched portion, 9b Front end surface 10 Stage base 10a Front surface, 10b Stage bottom portion, 10b1, 10b2 Through hole 10c Peripheral wall portion, 10c1 Outer circumferential surface, 10c2 Step portion 10c3 Concave curved surface, 10c4 Reduced diameter portion, 10c5 Minute protrusion 11, 11W Light guiding member 11a Front protrusion portion, 11a1 Front end surface, 11b Intermediate cylinder portion 11c Circumferential truncated cone portion, 11d Step portion, 11e Rear cylinder portion 11e1 Rear surface, 11f Leg portion, 11fb Rear end surface 11f1 to 11f7 Light guiding protrusion portion, 11f1a to 11f7a Engagement portion 12 Thermopile (temperature sensor), 12a Temperature-sensitive surface 13 Sensor substrate 13a Front surface 13b Receptacle 13c, 13c1 to 13c7 Photosensor 13d Switch 13e Through-hole 14 Base substrate 14a Front surface 14b Plug 14c Rear surface 14d LED 14dG LED group 14e FB photosensor 14eG FB photosensor group 14f Display element 14g Hole 14g1 Notch portion 14h Hole 14j Arc portion 14s Switch 15 Unit holder 15a Base portion 15a1 Through-hole 15b Protrusion 15b115b2 Step portion 16 Stage base 16a Rear end portion 16a1 Boss 16b Passage portion 17 Temperature sensor board 17a Center hole 17b Through hole 18 Relay lens 19 Seal ring 20 Filter holder 20a Front surface 20b1 to 20b7 Recessed portions 20c1 to 20c7 Through holes 20d Engaged portion 20e1 to 20e7 Pocket portion 20f Rear surface 21 Holder cover 21a Base portion 21b1 to 21b7 Through holes 21c Claw portion 31 to 37 Bandpass filter 41 Diffusion plate 41a Front surface 41b Rear surface 42 Diffusion member 51 Sugar content meter (handheld non-destructive sugar content meter) 52 Standard cover 52a Base body 52b Reflector, 52b1 Recess 52b2 Curved surface 81, 82 O-ring 91 Desk 100 Watermelon AS Fruit or vegetable A1 to A5, A7 Absorbance difference CL1, CL8, CLf, CL11 Axis, CLT Light receiving axis CT Control section CT1 Central processing unit (CPU), CT2 Correction section CT3 Light intensity processing section, CT4 Display control section, CT5 Light quantity control section CT6 Memory section D, Db to De, Dd1, De1, Df, Dg, Dh Diameter, Da Inner diameter F Filter unit JL Light quantity information, JT Temperature information K Housing, K1 Measuring section, K2 Grip section La, Lc Distance, Lb Thickness LT, LTR Light, LTa: Main optical axis, LTb, LTc: Optical path, LTd: Return light, LTe (LTe1 to LTe7): Light emitted from protrusion, Na: Tapping screw, Pc: Center position, P1: Virtual reference circle, P1a: Point, P2: Front-rear direction position, Q: Intensity characteristics, Qp: Peak, Q1 to Q7: Intensity, R, Ra: Radius, T, １ , T ２ Temperature Va: Gap (passageway) Vb: Space WB: Diffusion section θa: Inclination angle θb: Angle θp, θpa: Angle pitch λ1 to λ7: Wavelength (center wavelength)

Claims

1. A device comprising: a housing formed to include a grip portion that can be held and a measuring portion having an annular contact portion for contacting fruit or vegetable; a light source group consisting of a plurality of light sources arranged at intervals in a circumferential direction inside the housing; a light quantity control portion that controls the amount of light emitted by the light source group; a ring lens arranged in an inner portion surrounded by the contact portion and presenting a ring shape smaller than the contact portion, and emitting light emitted from the light source group in a ring shape to the outside of the housing; a light guiding member having one end face exposed inside the ring lens and the other end face located inside the housing and emitting light incident from the one end face to the outside from the other end face; a photosensor arranged within the housing and receiving light emitted from the other end face of the light guiding member; and a light intensity processing portion that determines absorbance based on the intensity of light received by the photosensor, wherein the light source group is controlled by the light quantity control portion to emit light of at least two different amounts, the light intensity processing unit determines a calibration curve of the sugar content of the fruit or vegetable based on the absorbance of the at least two different amounts of light and the Brix value at the depth of the fruit or vegetable corresponding to the amount of light.

2. The non-destructive measuring device for fruits and vegetables according to claim 1, wherein the light intensity processing section determines a Brix value distribution in the depth direction of the fruit or vegetable based on the absorbance of the at least two different amounts of light.

3. The non-destructive measuring device for fruits and vegetables according to claim 2, further comprising an electric circuit that charges an electrolytic capacitor from a power source when the light is not emitted, and supplies current from the power source and the electrolytic capacitor to the group of light sources when the light is emitted.

4. A non-destructive measuring device for fruits and vegetables as described in any one of claims 1 to 3, further comprising an annular relay lens between the group of light sources and the ring lens, for guiding light from the group of light sources to the ring lens.

5. A non-destructive measuring device for fruits and vegetables as described in any one of claims 1 to 3, wherein the main optical axis of the annular light emitted from the ring lens is inclined in a direction such that the diameter of the light decreases after it leaves the ring lens.

6. A non-destructive measuring device for fruits and vegetables as described in any one of claims 1 to 3, comprising at least m (m is an integer of 2 or greater) photosensors, and having bandpass filters, each having a center wavelength of m different wavelengths λ1 to λm, between each of the m photosensors and the other end face of the light-guiding member.

7. The non-destructive measuring device for fruits and vegetables as described in claim 6, wherein the light intensity processing unit determines the absorbance based on the received light intensities corresponding to the wavelengths λ1 to λm obtained by the m number of photosensors, and calculates a Brix value from the determined absorbance.

8. A non-destructive measuring device for fresh produce as described in any one of claims 1 to 3, wherein the grip portion has a longitudinal axis and is formed so as to be graspable, and the measuring portion is formed at one end of the longitudinal axis of the grip portion with the extension direction of the abutment portion along the longitudinal axis, and the tip surface of the abutment portion is located at a position protruding beyond the surface of the grip portion.

9. A non-destructive measuring device for fresh produce as described in any one of claims 1 to 3, further comprising a diffusion section for diffusing light passing through between a surface of the fresh produce surrounded by the contact section and the other end face of the light-guiding member when the fresh produce is in contact with the contact section.

10. A non-destructive measurement method for fruits and vegetables, comprising: a fruit or vegetable contacting step of bringing the fruit or vegetable into contact with a measuring unit; a light emitting step of emitting light from a group of multiple light sources onto the fruit or vegetable and causing the light to enter the interior of the fruit or vegetable; a light receiving step of receiving with a photosensor the light that is diffusely reflected inside the fruit or vegetable and some of which is absorbed with characteristics corresponding to the state of the fruit or vegetable and emitted to the outside; and a light intensity processing step of determining an absorbance based on the intensity of light received by the photosensor, wherein the light emitting step is a multi-stage light emitting step of emitting light with at least two different intensities, and the light intensity processing step includes a step of determining a calibration curve for the sugar content of the fruit or vegetable based on the absorbance of the at least two different intensities of light and the Brix value at a depth in the fruit or vegetable corresponding to the light intensities.

11. The non-destructive measurement method for fruits and vegetables according to claim 10, wherein the light intensity processing step includes a step of determining a Brix value distribution in the depth direction of the fruit or vegetable based on the absorbance of the at least two different amounts of light.

12. The non-destructive measurement method for fruits and vegetables as described in claim 11, wherein the multi-stage light emission process includes a process of charging an electrolytic capacitor from a power source when the light is not emitted, and supplying current from the power source and the electrolytic capacitor to the group of light sources when the light is emitted.

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