JPH09119896A - Nondestructive measuring apparatus for sugar content of fruits and vegetables making use of sunlight or incandescent lamp light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nondestructive measuring apparatus by which the state of the sugar content of the fruits and vegetables as an object can be detected and indicated by a measurement at one point of time without destroying the fruits and the vegetables as the object by a method wherein an indication on a display is proportional to the sugar content of the fruits and vegetables. SOLUTION: In a state that condensing part 2 is pressed to the fruits and vegetables 1, to be measured, which is irradiated with sunlight or incandescent lamp light, the component of a wavelength λ1 and the component of a wavelength λ2 are extracted respectively by spectral filters 3, 3a. Then, detection signals e1 , e2 are detected by photodetector 4, 4a, they are amplified by variable amplifiers 5, 5a, a fixed-gain amplifier 6 and an adjustable-gain amplifier 6a so as to become amplification outputs V1 , V2 . A difference signal between the output V1 and a reference voltage Vs is compared and amplified by a comparison and control amplifier 7 so as to become a control voltage Vc , the voltage Vc adjusts the amplification degree of the amplfiers 5, 5a, and the difference signal is controlled to become 0. By this control operation, a graduation on an output display 9 can be read directly in a state that the ratio of V2 /V1 maintains the V1 at a constant value. In addition, the name of the fruit or the vegetable 1 is recorded in a corresponding sugar-content distribution region on the graduation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring and instructing the sugar content of a fruit vegetable growing in a field or a fruit vegetable harvested.

[0002]

BACKGROUND OF THE INVENTION Watermelons, melons, etc. are not ones that allow anyone to judge the ripeness easily and surely from the appearance of fruits. In addition, although it is not easy to determine whether or not ripeness is present, it is not a matter that some percentage of unripe fruits in the harvested product may be mixed therein, and it is desirable that the harvested product is surely 100% ripe. Therefore, judgment of ripeness at the time of harvest is extremely important, and the effort is evaluated as credit of the production area.

Conventionally, based on a long-term research result on the number of days after flowering (correctly, cumulative temperature) required for maturation and an empirical / subjective evaluation of appearance changes accompanying maturity, a certain date of 5 Six fruits were sliced and tasted, and the ripeness and quality were confirmed to determine the harvest date. However, individual fruits and vegetables have different maturation processes depending on cultivar, weather, fruit size, sunshine, and nutritional conditions (especially nitrogen content), so fruit vegetables growing in the field without trial-cutting. The non-destructive determination of the ripeness of the rice and the strong desire to harvest only ripe products. Until now, appearance changes with maturity, such as size,
Research has also been conducted on quantitative measurement of color, hand tapping sound, specific gravity, etc., as a measure of aptitude, but it has not been put to practical use. In addition, regarding the quantification of the evaluation of the eating quality of pulp, there is a strong correlation with the portable refractometer measurement, and the sugar content is the maximum at full maturity, but the sugar content decreases due to self-breathing when overripe. Have also been reported. However, it is not that sugar content and ripeness correspond to each other, as watermelon has less sweetness in cold years and sweetness in hot years.

In recent years, due to the significant development of optical technology, image processing technology, computer application technology, etc., near-infrared laser light is radiated into a target field for selection of watermelons, melons, tangerines, peaches, pears, etc. A system for performing non-destructive and nondestructive evaluation of fruit quality is being introduced (Japanese Patent Laid-Open No. 1-2162).
65, JP-A-1-301147). In a system using these near-infrared laser light sources, sunlight or artificial illumination becomes a disturbance source, so a light-shielding facility is required at the measurement location, and the device becomes large. Furthermore, the spectroscopic analysis device that requires computer processing is extremely expensive, and is not suitable for small-scale fruit and vegetable producers who mainly sell directly to consumers.

In order to solve such a problem, the inventor of the present invention can easily and surely determine the maturity of a fruit vegetable growing in a field without destructing the ripeness of the fruit vegetable. We proposed a method and a device for measuring the ripeness of fruits and vegetables using the above method (see Japanese Patent Application No. 6-284578, "A method and a device for measuring ripeness of fruits and vegetables using sunlight").

[0006]

However, the non-destructive measurement method of maturity of fruits and vegetables using sunlight according to this prior application is included in the transmitted light of the sunlight of fruits and vegetables that are irradiated with sunlight. This is based on the principle that the ripeness of the fruit vegetables is judged by paying attention to the fact that the intensity ratio of two specific wavelength components in the near infrared shows a minimum value or a maximum value when the fruit vegetables are fully ripe. For this reason, when determining the ripeness of a fruit, in principle, the value of the intensity ratio at the time when the intensity ratio shows the maximum and the minimum and the measured value of the intensity ratio at the time before and after that time are calculated. It is necessary to make a comparison, and it takes a certain elapsed time to obtain the measurement result. This is suitable when the farmer decides the time of harvest while measuring the maturity of growing watermelons, melons, etc., but when measuring the sugar content of the target fruit vegetables at one point, Inappropriate.

An object of the present invention is a non-destructive measuring apparatus for sugar content of fruits and vegetables using sunlight or light from an incandescent lamp capable of detecting and instructing the sugar content state of the target fruits and vegetables without destroying the target fruits and vegetables by measurement at a temporary point. To provide.

[0008]

To achieve this object, the sugar content non-destructive measuring apparatus for fruits and vegetables utilizing sunlight or incandescent lamp light according to the present invention is irradiated with sunlight or incandescent lamp light. A light condensing portion pressed against the surface of the fruit and vegetables in order to extract the transmitted light or the scattered light of the sunlight or incandescent light of the fruit and vegetables, and the absorption of moisture or sugar from the transmitted light or the scattered light is small. A near-infrared filter for extracting two near-infrared specific wavelength components corresponding to the second wavelength, which has a large absorption by the first wavelength and sucrose but a small absorption by water, A photodetector for converting a specific wavelength component into two corresponding electric signals; a comparator for taking the output ratio of the two electric signals with the electric signal corresponding to the first wavelength being a constant value; Output obtained by the instrument And a display for displaying the indication on the display is configured to be proportional to the sugar content of the fruit vegetables.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the device of the present invention, the first
Is suitable for the 850 nm band and the second wavelength is suitable for the 1050 nm band as described later. According to the device of the present invention,
Since the indicator value of the indicator is substantially proportional to the sugar content of the target fruit and vegetables, it is possible to detect and instruct the sugar content state of the target fruit and vegetables by measuring at one point, and the scales of the indicators are almost evenly spaced. It is practically convenient for reading. For fruits and vegetables growing in the field, it is possible to indicate the sugar content of the target fruits and vegetables simply by applying a handy type measuring device to the target fruits and vegetables using sunlight. For harvested fruits and vegetables, simply put the target fruits and vegetables on a stand-alone type measuring instrument at each stage such as the sorting field, market, wholesale, retail, etc.
The sugar content of the target fruit can be indicated. In this case, since the sugar content distribution region is determined for each target fruit vegetable such as melon, watermelon, apple, pear, tangerine, peach, strawberry, tomato, each name of the target fruit vegetable is assigned to the corresponding sugar content distribution region on the scale. If it is described, it is convenient for actual use.

[0010]

FIG. 1 shows an embodiment of the device of the present invention.
1 is a fruit or vegetable to be measured which is irradiated with sunlight or light from an incandescent lamp, and 2 is pressed against the surface of the fruit or vegetable 1 to extract transmitted light or scattered light of the light from the fruit or vegetable 1 Focusing units 3, 3a are spectral filters for extracting two near-infrared wavelength components λ ₁ and λ ₂ from the extracted transmitted light, and 4, 4a are two near-infrared wavelength components Photodetectors for converting λ ₁ and λ ₂ into corresponding two electric signals e ₁ and e ₂ , 5, 5a are variable gain amplifiers for amplifying the two electric signals, 6 and 6a are variable gain amplifiers 5, A fixed gain amplifier and a semi-fixed gain amplifier for amplifying the output of 5a to a required level, and 7 amplifies a difference signal V _d between the amplified output v _{1 of one} of the amplified two electric signals e ₁ and the reference voltage v _s. Control output V for controlling each of the variable gain amplifiers 5 and 5a A comparison control amplifier feeding back as c, 8 is a switch for selecting _{one of} the outputs v ₁ and v ₂ of the fixed gain amplifier 6 and the semi-fixed gain amplifier 6a, and 9 is the output v ₁ selected by the switch 8. , V ₂ and an indicator for displaying the value of v ₂ .

In this embodiment, the wavelength λ ₁ is set near 850 nm where absorption by water and sugar is extremely small, and the wavelength λ ₂ is set near 1050 nm where absorption by sucrose is large but absorption by water is small. . This is a reference [S. Kawano et al "Determination of Suga
r Contentin Intact Peaches by Near Infrared Spectr
oscopy with Fiber Optics in In-teractance Mode "J.
Japan Soc. Hort. Sci. 61 (2), P450, 1992], the absorption of water and sugar is small near the wavelength of 850 nm as shown in FIG.
It is based on the understanding that absorption of sucrose is large in the vicinity, but absorption by water is small. Therefore, in the state where the condensing part 2 is pressed against the measured fruit 1 irradiated with sunlight or incandescent lamp light, the wavelength λ ₁ component and the wavelength λ ₂ component are extracted by the spectral filters 3 and 3a, respectively. The detection signals e ₁ and e ₂ are detected by the photodetectors 4 and 4a, and amplified by the variable amplifiers 5 and 5a and the fixed gain amplifier 6 and the semi-fixed gain amplifier 6a to become amplified outputs v ₁ and v ₂ . In this case, the component of wavelength λ ₂ is largely absorbed by the sucrose component contained in the measured fruit and vegetable 1, but the component of wavelength λ ₁ is less absorbed by the sucrose component, so be sure to use v ₁
> V ₂ . The difference signal V _d between the amplified output v ₁ and the reference voltage v _s is comparatively amplified by the comparison control amplifier 7 to become the control voltage V _c , and this control voltage V _c adjusts the amplification degree of the variable amplifiers 5 and 5a, Control is performed so that the difference signal V _d = 0.

According to this control operation, within a certain level range of the detection signal e ₁ , as shown in FIG. 3, the amplified output v ₁ of the detection signal e ₁ has a substantially constant value corresponding to the reference voltage v _s regardless of the incident light amount. Will be maintained. At this output value, if the switch 8 is switched to the v ₁ side and the instruction of the output indicator 9 indicates the scale of the maximum value 1.0, the output when the switch 8 is switched to the v ₂ side The instruction of the indicator 9 will be 0.5 in the example of FIG. By this control operation, the ratio of v ₂ / v ₁ can be directly read on the scale of the output display 9 while maintaining v ₁ at a constant value of 1.0. In this case, the portions indicated by thick lines of v ₁ and v ₂ in FIG. 3 are the normal operation range of this embodiment.

The operation of the present invention will be described further supplementarily. The symbols used to explain the operation are shown in FIG. First, the sunlight or incandescent lamp light used for measurement is directly applied to the light condensing unit 2, and a semi-fixed gain is set so that the output of the measurement system operating for the component of wavelength λ ₂ becomes equal to the reference voltage value v _s. adjusting the gain a _m of the amplifier 6a, since the reference system output that operates on the wavelength lambda ₁ of the component is equal to the reference voltage v _s, the following equation holds.

(Equation 1) Although the spectral intensity distributions of sunlight and incandescent light bulb are different as shown in FIG. 7, respectively, P _ro is the light intensity of the wavelength component with a wavelength of 850 nm or more, and P _mo is the light intensity of the wavelength component with a wavelength of 1050 nm or more. . Note that the spectral intensity distribution of the fluorescent lamp is shown by a broken line for reference, but the component with a wavelength of 850 nm or more is extremely small and cannot be used as the light source of the device of the present invention.

Next, when the scattered light transmitted through the fruits and vegetables is picked up by the condenser 2 through the fruits and vegetables, the light input P _r of the standard system is αP.
_{At ro} , the optical input of the measurement system decreases to β _mo . Here, α is the attenuation mainly due to the size of the type of fruit vegetable (mainly the skin thickness), and β is the attenuation further due to the sugar content. The measurement system output e at that time is

[Equation 2] e = βP _mo · F _m · S _m · G · A _m (2) The reference system output is in the normal operating range.

Since E = αP _ro · F _r · S _r · G · A _r ,

(Equation 4) Substituting equations (1) and (3) into equation (2),

(Equation 5) Therefore, the output of the measurement system depends only on the light attenuation characteristics of the fruit and vegetables, and is not affected by the spectral intensity characteristics of the irradiation light source or the characteristics of the reference system and each element constituting the measurement system. In addition, when using sunlight, if the amplifier gain is optimally designed, it can be operated in the normal operation range whether it is sunny or cloudy.

A non-destructive sugar content meter having the structure shown in FIG.
Melon growing in the field was collected for measurement, placed as a round ball on the light collecting unit 2 and measured under sunlight, and the indicator indication was taken and the latter half of the measurement was cut, and a portable refractometer was used. The black circles in FIG. 5 show the comparison of the sugar content values of the fruit juice of the content measured by the above method. In addition, the melons after harvesting were cut in half, and the half-cut melons whose sugar content in the fruit juice had been measured were placed on the light-collecting part 2 of the prototype and compared with the indicated values measured under sunlight irradiation. It is a cross mark of 5.

The difference between the two measurements is that the transmitted light of direct sunlight is measured (marked by X) or the transmitted scattered light of reflected sunlight from the ground is measured (marked by ●). However, in all measurements, an indicated value proportional to the sugar content of the fruit juice was obtained. From this result, it is possible to replace the display of the output display 9 with the sugar content scales at equal intervals, and for the sugar content of the fruit and vegetables, for the fruit and vegetables growing in the field irradiated with sunlight, the light collecting unit 2 is used for the fruit peeling. It was proved that the harvested fruits and vegetables can be measured non-destructively simply by placing them on the light collecting unit 2 when measuring the harvested fruits and vegetables under the sunlight.

Even when a 60 W incandescent light bulb for illumination is used indoors where sunlight is not applied, an irradiation intensity comparable to that of sunlight can be obtained by adjusting the distance from the fruit surface.
In that case, the gain of the semi-fixed gain amplifier 6a of the measurement system only needs to be adjusted so as to satisfy the relationship of equation (1).
It is not necessary to design and manufacture the one for sunlight and the one for incandescent lamp separately.

FIG. 6 shows an example of measurement of the sugar content and the output instruction value of the fruit 1 to be measured, and it is recognized that there is a substantially linear high correlation between the sugar content and the output instruction value.
It is obvious that it is possible to use a scale in which the output indication value is replaced with the sugar content. Moreover, as shown in the figure, since the sugar content distribution range is specified by the type of fruit and vegetables, the type of fruit and vegetables is displayed on the sugar content scale, and the normal value of the sugar content of the fruit and vegetables is known to facilitate measurement. It is possible.

In the construction of the measuring system, the spectral intensity distribution of sunlight shown by or the spectral intensity distribution of incandescent lamp light shown by and the near infrared (Ge-PD or InGaAs-) are shown.
It can be utilized that the spectral sensitivity characteristic of PD) is complementary (supplements the decrease in the intensity of sunlight with the increase in the light receiving sensitivity) in the wavelength band to be measured as shown in FIG. Further, since the near-infrared photodiode has no light receiving sensitivity at 0.6 μm or less, it is possible to eliminate the adverse effect of the sunlight component passing through the sub-pass band of the spectral filter, which is generally present at 0.6 μm or less.

As the structure of the device of the present invention, as shown in the plan view (a) and side view (b) of FIG. 8, the grip portion 18 is arranged below the device so that it can be easily measured and handled. , The solar cell 17 is arranged on the surface of the device,
The amplifier, the output instruction unit 16 and the like may be driven by the solar cell 7. As a specific example, height 15 cm, width 9 c
m, depth 5 cm. The driving power source is, for example, four AA batteries.

[0021]

As described in detail above, according to the present invention, the sugar content indicating the ripeness of a fruit or vegetable to be measured is “applied” to the fruit or vegetable without cutting and tasting the fruit or vegetable. Or, since it can be measured non-destructively by "putting it on", a simple and inexpensive quality evaluation device can be realized, and even a normal operator who does not have a high degree of skill can judge the ripeness of the fruit and vegetables. It is obvious that it will be useful for labor saving and securing credit when it is used at each stage of land, sorting ground, market, wholesale and retail. In addition, at a fruit vegetable store, it can be useful for guaranteeing the quality of products at the storefront regardless of the rain.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a device of the present invention.

FIG. 2 is a characteristic diagram comparing the light absorption characteristics of sucrose and water.

FIG. 3 is a characteristic diagram for explaining measured values and indicating scales according to the present invention.

FIG. 4 is a block diagram for explaining the operation principle of the device of the present invention.

FIG. 5 is a characteristic diagram showing a measurement example according to the present invention.

FIG. 6 is a characteristic diagram showing a measurement example according to the present invention.

FIG. 7 is a characteristic diagram showing a spectral intensity distribution characteristic of sunlight and incandescent lamp light used in the present invention and a spectral intensity characteristic of a photodetector.

FIG. 8 is a plan view (a) and a side view (b) showing a structural example of the device of the present invention.

[Explanation of symbols]

 1 Fruit to be measured 2 Condenser part 3, 3a Spectral filter 4, 4a Photodetector 5, 5a Variable gain amplifier 6 Fixed gain amplifier 6a Semi-fixed gain amplifier 7 Comparison control amplifier 8 Switch 9 Output indicator 16 Output indicator 17 Solar Battery 18 grip

Claims (2)

[Claims] 1. A light condensing unit that is pressed against the surface of the fruit or vegetables to receive the transmitted light or the scattered light of the sunlight or incandescent lamp light of the fruit or vegetables that are irradiated with sunlight or incandescent lamp light. From the transmitted light or the transmitted scattered light, two specific wavelength components of near-infrared light corresponding to a first wavelength with little absorption by moisture and sugar and a second wavelength with large absorption by sucrose but little absorption by moisture are provided. A near-infrared filter for taking out, a photodetector for converting the two specific wavelength components of the near-infrared into two corresponding electrical signals, and a constant value for the electrical signal corresponding to the first wavelength A comparator for taking an output ratio of the two electric signals, and a display for displaying an output ratio obtained by the comparator, and an instruction on the display is configured to be proportional to the sugar content of the fruit and vegetables. Sunlight or incandescent light bulb Sugar content non-destructive measurement device of the fruits and vegetables that you use. 2. The two near infrared filters have a cutoff wavelength of 8
Long wavelength pass filter of 50nm and cutoff wavelength of 1,050n
The sugar content non-destructive measuring device for fruits and vegetables using sunlight or incandescent lamp light according to claim 1, which is a combination with a long wavelength pass filter of m.