JPH1144638A - Method for measuring fruit sugar level and fruit sugar level meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the fruit sugar level measuring method and fruit sugar level meter which eliminate the need to set a large measurement range for a photodetector and can measure the sugar level of a fruit having a thick skin with simple constitution. SOLUTION: This sugar level meter measures the sugar level from the transmitted light obtained by irradiating the fruit having the thick skin such as a melon with light. In this case, the light which is hardly transmitted through the fruit 2 and has wavelength needed for measurement is compensated with the light from a laser light source 7, so the intensity of the light having the wavelength to be measured becomes nearly equal and the sugar level can precisely be measured by the simple constitution even with any wavelength without setting the measurement range of the photodetector 12 large. When white light sources 5 and laser light sources 7 are arranged radially around the fruit 2, the fruit 2 is irradiated with the light of the illumination system 3 from all directions, so a measurement error resulting from the size and position of the fruit 2 is reduced to improve the measurement precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a sugar content of a fruit based on transmitted light obtained by irradiating light to a thick-skinned fruit such as melon and a fruit refractometer.

[0002]

2. Description of the Related Art Generally, harvested vegetables and fruits (rapeseed fruits)
Is shipped after various inspection processes such as appearance inspection and weight inspection. In the inspection process of fruits, particularly peaches, pears, apples, and the like, there is a process of optically nondestructively inspecting a sugar content component using a fruit refractometer. This fruit refractometer irradiates a fruit with white light such as a halogen lamp, measures the distribution of the intensity of the transmitted light with respect to the wavelength, and measures the sugar content by analyzing the distribution. Absorption spectroscopy technique is used.

[0003]

By the way, as for the relationship between the transmitted light intensity and the wavelength by the conventional fruit refractometer, the transmitted light intensity greatly changes in a wavelength range of 700 to 1000 nm as shown in FIG. That is, a wavelength of 700 to 800 nm
In the range, the transmitted light intensity is the size required for measurement,
In the range of 900 to 1000 nm, the transmitted light intensity decreases and affects the measurement. Therefore, in order to perform measurement at any wavelength without lowering the measurement accuracy, it is necessary to increase the measurement range of the light receiver.

[0004] However, even if the measuring range of the photodetector is large, it is not possible to obtain sufficient information on the sugar content in a wavelength region where the transmitted light intensity of white light is small. For this reason, in order to sufficiently obtain information on the sugar content in a wavelength region where the transmitted light intensity of white light is small, a new circuit (for example, a lock-in amplifier) must be added to the fruit sugar content meter, and the device becomes complicated. There was a problem. FIG. 5 is a diagram showing the relationship between the transmitted light intensity and the wavelength by a conventional fruit refractometer, with the horizontal axis representing the wavelength and the vertical axis representing the transmitted light intensity.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a fruit refractometer capable of measuring the sugar content of thick-skinned fruits with a simple configuration without having to increase the measuring range of a light receiver. Is to do.

[0006]

Means for Solving the Problems In order to achieve the above object, the present invention relates to a method for measuring the sugar content from transmitted light obtained by irradiating light to a thick-skinned fruit such as melon.
The fruits are illuminated with white light and hard to penetrate the fruits.They are irradiated with laser light of the wavelength required for measurement, and the transmitted light scattered and transmitted in the fruits is spectrally separated. It is converted into an electric signal and the sugar content of the fruit is calculated based on the obtained electric signal.

[0007] In order to achieve the above object, the present invention provides a fruit refractometer for measuring sugar content from transmitted light obtained by irradiating light to a thick-skinned fruit such as melon. A light source, a laser light source that irradiates the fruit with light of a wavelength required for measurement that is difficult to transmit through the fruit, a spectroscope that disperses the transmitted light scattered and transmitted in the fruit, and a spectrum that is separated by the spectrometer And a signal processing means for calculating and processing the sugar content of the fruit based on the electric signal from the light receiver.

In the present invention, in addition to the above configuration, a plurality of white light sources and a plurality of laser light sources may be radially arranged around the fruit.

In the present invention, in addition to the above configuration, the oscillation wavelength of the laser light source may be different.

[0010] With the above structure, it is difficult to permeate the fruit,
In addition, since the light having the wavelength necessary for the measurement is supplemented by the light from the laser light source, the intensity of the transmitted light at the wavelength to be measured is substantially the same. Therefore, the sugar content can be accurately measured at any wavelength with a simple configuration without increasing the measurement range of the light receiver.

When a plurality of white light sources and a plurality of laser light sources are arranged radially around a fruit, the illumination system light irradiates the fruit from all directions, thereby reducing measurement errors due to the size and position of the fruit. Measurement accuracy is further improved. When the oscillation wavelengths of the plurality of laser light sources are different, the information amount of the transmitted light intensity of the fruit increases, so that the sugar content of the fruit can be measured more accurately.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram showing an embodiment of a fruit sugar content meter to which the method for measuring fruit sugar content of the present invention is applied.

The fruit refractometer 1 comprises an illumination system 3 for irradiating the fruit with light, and a fruit refractometer main body 4 for measuring the sugar content of the fruit from light scattered and transmitted in the fruit.

The melon 2 as a fruit is held by a holding member (not shown). 5 is a halogen lamp for irradiating the melon 2 with white light (for example, output 100 W)
It is. Reference numeral 7 denotes a semiconductor laser (for example, an output of 5 W) as a laser light source that hardly transmits the melon 2 and oscillates light having a wavelength required for measurement (for example, sucrose absorption wavelength λ1). The illumination system 3 is composed of the halogen lamp 5 and the semiconductor laser 7.

The fruit refractometer main body 4 disposed below the melon 2 has an optical fiber 8 disposed so that the transmitted light scattered and transmitted in the melon 2 is incident on one end (the upper end in the figure). A slit plate 9 provided at the other end (lower end) of the optical fiber 8, a convex lens 10 provided on the emission side (lower side) of the slit plate 9 to make the light from the slit plate 9 parallel, and an emission of the convex lens 10. A diffraction grating 11 arranged obliquely (approximately 45 degrees) on the side and splitting the light emitted from the convex lens 10, and a spectrum arranged on the output side of the diffraction grating 11 and receiving the spectrum split by the diffraction grating 11 and receiving electricity for each wavelength. An array detector 12 serving as a light receiver for converting into a signal, a housing 13 for housing and holding these optical fiber 8, slit plate 9, convex lens 10, diffraction grating 11, and array detector 12;
It comprises a microcomputer 14 serving as a signal processing means for calculating the sugar content of the melon 2 based on the electric signal from the array detector 12. The array detector 12 is, for example, one in which a large number of photodiodes (or phototransistors) are arranged in an upper and lower row, and converts received light into electric signals.
The optical fiber 8 has a condensing lens 15 at the upper end, so that the incident light propagates through the core 16 after being condensed.

The operation of the fruit refractometer shown in FIG. 1 will be described.

When the halogen lamp 5 and the semiconductor laser 7 emit light, the white light and the laser light are irradiated on the melon 2, and the white light and the laser light are scattered in the melon 2 and transmitted through the melon 2, and the optical fiber 8 Then, the light enters the diffraction grating 11 via the convex lens 10. The transmitted light incident on the diffraction grating 11 is split and incident on the light receiving surface of the array detector 12 from bottom to top in the order of violet, blue, green, brown, yellow, orange, and red. These spectra incident on the array detector 12 are converted into electric signals for each wavelength, and the converted electric signals are input to the microcomputer 14. The characteristic curve shown in FIG. 2 is obtained by arithmetically processing the signals by the microcomputer 14.

FIG. 2 is a diagram showing the relationship between the transmitted light intensity and the wavelength by the fruit refractometer shown in FIG. 1, wherein the horizontal axis indicates the wavelength and the vertical axis indicates the transmitted light intensity.

As shown in FIG. 2, the wavelength is 700 to 800 n.
On the short wavelength side of m, the transmitted light by the white light from the halogen lamp 5 is observed, and on the long wavelength side of 900 to 1000 nm, the transmitted light by the laser light from the semiconductor laser 7 together with the white light from the halogen lamp 5 (peak P1). ) Is observed. That is, the light from the semiconductor laser 7 which is hardly transmitted through the melon 2 and has a wavelength equal to the absorption wavelength of sucrose is supplemented by the light from the semiconductor laser 7, so that the wavelength λ1
Are substantially at the same level. Therefore, it is not necessary to increase the measurement range of the array detector 12, and the sugar content can be accurately measured with a simple configuration.

That is, the fruit is irradiated with white light and hardly penetrates the fruit, and is irradiated with a laser beam having a wavelength required for measurement, and the transmitted light scattered and transmitted in the fruit is spectrally separated. By converting the spectrum to an electric signal for each wavelength and calculating the sugar content of the fruit based on the obtained electric signal, it is not necessary to increase the measurement range of the photodetector, and the simple configuration of Sugar content can be measured.

FIG. 3 is a layout diagram showing a modification of the illumination system of the fruit refractometer of the present invention.

The difference from the embodiment shown in FIG.
The point is that a plurality of halogen lamps and twelve semiconductor lasers are arranged around the melon.

As shown in FIG.
a to 5d surround the melon 2 and are arranged so as to emit white light toward the melon 2 in directions indicated by arrows H1 to H4. Three semiconductor lasers (wavelengths λ1, λ2, λ3) 7a having different oscillation wavelengths are provided between the halogen lamps 5a and 5b.
7c are arranged so as to irradiate the laser beam in the directions of arrows L1 to L3 toward the melon 2. Halogen lamp 5
Three semiconductor lasers 7d, 7e and 7f having oscillation wavelengths λ1, λ2 and λ3 are arranged between b and 5c. Similarly, three semiconductor lasers 7g to 7l having oscillation wavelengths λ1, λ2 and λ3 are arranged between the halogen lamps 5c and 5d and between the halogen lamps 5d and 5a, respectively. That is, the halogen lamps 5a to 5d and the semiconductor lasers 7a to 7l are radially arranged around the melon 2.

Here, the semiconductor lasers 7a, 7d, 7g,
The oscillation wavelength λ1 of 7j is hard to pass through the melon 2 and corresponds to the absorption wavelength of sucrose, and the semiconductor lasers 7b, 7e,
The oscillation wavelengths λ2 of 7h and 7k are hardly transmitted through the melon 2 and correspond to the absorption wavelength of fructose.
The oscillation wavelengths λ3 of 7f, 7i, and 7l are not easily transmitted through the melon 2 and correspond to the absorption wavelength of glucose, but are not limited thereto.

As described above, the plurality of halogen lamps 5a-5
When d and the plurality of semiconductor lasers 7a to 7l are radially arranged around the melon 2, three peaks P1 to P3 are observed on the long wavelength side in the characteristic curve shown in FIG. The transmitted light intensity of the required wavelength can be obtained over the wavelength side. In addition, since the light of the illumination system is applied to the fruit from all directions, measurement errors due to the size and position of the melon are reduced, and the measurement accuracy is further improved. FIG. 4 is a diagram showing the relationship between transmitted light intensity and wavelength when the illumination system of the fruit refractometer shown in FIG. 1 is changed.

In the above, since the light having a wavelength necessary for measurement is hardly transmitted through the melon and the light from the laser light source is supplemented by the light from the laser light source, the transmitted light intensity of the wavelength to be measured is substantially the same level. Therefore, it is not necessary to increase the measurement range of the light receiver.

When a plurality of white light sources and a plurality of laser light sources are arranged radially around the fruit, the light applied to the fruit increases without being concentrated, so that the measurement accuracy is improved. When the oscillation wavelengths of the plurality of laser light sources are different, the transmitted light intensity for each absorption wavelength of the fruit can be grasped, so that the sugar content of the fruit can be measured more accurately.

In this embodiment, a halogen lamp is used as a white light source. However, the present invention is not limited to this, and a lamp such as a tungsten lamp or a xenon lamp may be used. It is sufficient that the melon is not heated while being scattered and transmitted in the melon. In the present embodiment, a semiconductor laser is used as a laser light source. However, the present invention is not limited to this, and other types of laser light sources may be used. It suffices if the melon does not pierce or burn. Further, although a diffraction grating is used as a spectroscope, an optical component such as a prism may be used.

[0030]

In summary, according to the present invention, the following excellent effects are exhibited.

In a fruit sugar content method for measuring sugar content from transmitted light obtained by irradiating light to a thick-skinned fruit such as melon,
Since the light having a wavelength necessary for measurement is hardly transmitted through the fruit and the light from the laser light source is supplemented by the light from the laser light source, the intensity of the light having the wavelength to be measured is substantially the same. For this reason, it is not necessary to set a large measurement range with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a fruit sugar content meter to which a method for measuring fruit sugar content of the present invention is applied.

FIG. 2 is a diagram showing a relationship between transmitted light intensity and wavelength by the fruit refractometer shown in FIG.

FIG. 3 is a layout diagram showing a modification of the illumination system of the fruit refractometer of the present invention.

FIG. 4 is a diagram showing the relationship between transmitted light intensity and wavelength when the illumination system of the fruit refractometer shown in FIG. 1 is changed.

FIG. 5 is a diagram showing the relationship between the transmitted light intensity and the wavelength by a conventional fruit refractometer.

[Explanation of symbols]

 2 Fruit (melon) 3 Illumination system 5 White light source (halogen lamp) 7 Laser light source (semiconductor laser) 11 Spectroscope (diffraction grating) 12 Photodetector (array detector)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshiaki Ogawa 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries, Ltd.

Claims (4)

[Claims] 1. A fruit sugar content method for measuring sugar content from transmitted light obtained by irradiating light to a thick-skinned fruit such as melon, wherein the fruit is irradiated with white light and hardly penetrates the fruit. Irradiating a laser beam of a wavelength necessary for the measurement, disperses the transmitted light scattered and transmitted in the fruit, converts the dispersed spectrum into an electric signal for each wavelength, and based on the obtained electric signal, A method for measuring the sugar content of a fruit, comprising calculating the sugar content of the fruit. 2. A fruit refractometer for measuring sugar content from transmitted light obtained by irradiating light to a thick-skinned fruit such as melon,
A white light source that irradiates fruits with white light, a laser light source that irradiates fruits with light that is difficult to transmit through fruits and has a wavelength necessary for measurement, and a spectroscope that disperses transmitted light that is scattered and transmitted within the fruits A light receiving device that receives the spectrum separated by the spectroscope and converts the spectrum into an electric signal for each wavelength; and a signal processing operation unit that performs an arithmetic process on the sugar content of the fruit based on the electric signal from the light receiving device. A fruit refractometer provided with: 3. The fruit refractometer according to claim 2, wherein a plurality of white light sources and a plurality of laser light sources are radially arranged around the fruit. 4. The fruit refractometer according to claim 3, wherein the laser light sources have different oscillation wavelengths.