Rice ball filling shortage inspection device

Abstract

To provide a rice ball filling shortage inspection device with high inspection accuracy and low-cost device structure.SOLUTION: A rice ball filling shortage inspection device 10 includes: a gap 16 between an upstream conveyor 12 and a downstream conveyor 14 which are separated sections of a conveyor transporting a rice ball 1 before shaping and individual packaging; a light-emitting part 20 which irradiates the rice ball 1 passing through the gap 16 with a narrow-band monochromatic light of one of visible light spectrums at above and below of the gap 16; a light sensor 30 which is oppositely arranged to measure amount of inspection light scattered within the rice ball 1 and emitted from its rear surface; and a determination part 40 which determines presence / absence of a filling in the rice ball 1 according to the amount of the inspection light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ingredient-missing inspection device for rice balls that non-destructively inspects for missing ingredients, i.e., rice balls formed without any ingredients on a rice ball production line. [Background technology]

[0002] Commercially available onigiri are formed on a production line by adding ingredients to a predetermined amount of rice in a forming machine. Then, each onigiri is individually wrapped in film in a packaging machine. Finally, a metal detector is used to check for foreign matter contamination. Before packaging, the onigiri formed by the forming machine are inspected to ensure that the ingredients are still present. This is because if defects are found in the ingredients after the individual packaging, the film would be wasted. Since visual inspection of the ingredients inside onigiri on the production line is impossible, X-ray inspection equipment has traditionally been used. X-ray inspection equipment is a non-destructive testing device that visualizes the internal structure of products by passing them through the food production line, detecting the presence of foreign matter or defects. X-ray inspection equipment is highly accurate and reliable, contributing greatly to product quality control and improved food safety. However, its large size limits installation locations. Other issues include concerns about radiation exposure to workers and the high cost of the equipment.

[0003] Another example of an object inspection device is a device that performs inspection by irradiating light, as described in Patent Document 1. This device has a light irradiation unit that irradiates broadband light and a measurement unit that measures the spectral characteristics of light transmitted through the object when irradiated with broadband light at the inspection position. However, broadband light disperses the light energy over a wide range of wavelengths, making it difficult to ensure an amount of light in a wavelength range that is advantageous for inspection.

[0004] The inspection device disclosed in Patent Document 2 includes a transmission illumination means for irradiating the inspection object with near-infrared light and a transmission light signal detection means for detecting a transmission light signal from the inspection object. However, near-infrared light has a long wavelength, and the thickness of an object through which it can penetrate is limited. Furthermore, inspection objects that contain a certain amount of moisture, such as rice balls, absorb near-infrared light, making it difficult to inspect rice balls that are 20 mm to 50 mm thick for the presence or absence of ingredients. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7325390 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-333177 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the problem to be solved by the present invention is to provide an onigiri ingredient shortage inspection device that has high inspection accuracy and an inexpensive device configuration. [Means for solving the problem]

[0007] As a first means for solving the above-mentioned problems, the present invention provides an onigiri ingredient shortage inspection device, which is characterized by providing a gap between an upstream conveyor and a downstream conveyor that are formed by dividing a conveyor that transports onigiri before they are formed and individually packaged, and arranging oppositely above and below the gap a light-emitting unit that irradiates one narrowband monochromatic light of visible light onto the onigiri that pass through the gap, and a photosensor that measures the amount of inspection light scattered inside the onigiri and emitted from the backside, and a judgment unit that judges whether the onigiri has ingredients or not based on the amount of inspection light. According to the first method, the amount of light can be measured even with an inexpensive optical sensor, making the overall device less expensive than conventional image processing methods using cameras, and it is possible to determine whether or not a rice ball has ingredients even while it is being transported at high speed. Even with a low-output light-emitting unit, by using monochromatic light, it is possible to measure a sufficient amount of inspection light concentrated in a narrow band with an inexpensive and compact device configuration, and it is possible to efficiently measure the scattering of the light irradiated onto the rice ball and the transmittance of the entire scattered light.

[0008] As a second means for solving the above problem, the present invention provides a rice ball ingredient shortage inspection device, which is characterized in that in the first means, the light-emitting unit is an LED element with a wavelength of 525 nm or 625 nm. According to the second method, when the output current ratio of the optical sensor of a defective product (without ingredients) was compared to that of a good product (with ingredients), it was found to be 12 times at 525 nm (green) and 5 times at 625 nm (red), which shows a large difference in current value and allows for accurate judgment.

[0009] As a third means for solving the above problem, the present invention provides a device for inspecting for missing ingredients in rice balls, which is characterized in that in the first means, the optical sensor has an optical filter on the sensor surface that emits monochromatic light from the light-emitting unit or that has the same color as the ingredients in the rice ball. According to the third means, the inspection light can easily pass through, and the influence of various wavelength components of external light can be prevented, thereby improving the accuracy of measuring the light amount by the optical sensor.

[0010] As a fourth means for solving the above problem, the present invention provides an onigiri ingredient shortage inspection device, characterized in that, in any one of the first to third means, one optical sensor is arranged, or multiple optical sensors are arranged in parallel along the gap. According to the fourth method, the optical sensor's directional characteristic data indicates that the angle at which relative sensitivity is reduced by half is within a ±20-degree range. Since the distance between the rice ball and the optical sensor is approximately 30 mm, the effective range of the rice ball surface within which the optical sensor can receive the inspection light re-emitted from the rice ball is a circle with a diameter of 22 mm. Considering a ±10 mm margin for deviation from the optical sensor's effective range due to misalignment of the rice ball's conveyance position during the manufacturing process, the result is 22 + 10 + 10 = 42 mm, meaning that small rice balls up to approximately 40 mm in diameter must be inspected with a single optical sensor. For rice balls larger than 40 mm, the range that can be reliably blocked even if the rice ball's conveyance position is misaligned by approximately ±10 mm far exceeds the 22-mm diameter range. Therefore, by placing multiple optical sensors along the gaps in the conveyor and efficiently capturing and summing the light scattered inside and transmitted through the rice ball, the accuracy of the measured light quantity can be improved, making it possible to measure even small light quantities.

[0011] As a fifth means for solving the above-mentioned problems, the present invention provides an onigiri ingredient shortage inspection device, characterized in that in the fourth means, the light-emitting unit emits monochromatic light in a flashing manner, and the optical sensor measures the amount of light synchronized with the flashing of the light-emitting unit. According to the fifth means, when the light source of the extraneous light that interferes with the inspection is a DC light that is not modulated, such as an incandescent lamp, the interference with the inspection performance caused by the DC extraneous light can be reduced.

[0012] As a sixth means for solving the above-mentioned problems, the present invention provides a rice ball ingredient shortage inspection device, which is characterized in that, in the fourth means, the light-emitting unit irradiates monochromatic light in a blinking pseudo-random pulse, and the optical sensor measures the amount of light synchronized with the blinking pseudo-random pulse of the light-emitting unit. According to the sixth aspect, when external light is 50 Hz or 60 Hz, or when high frequency driving is performed by an inverter, beat interference can be alleviated by using blinking with pseudo-random pulses. [Effects of the Invention]

[0013] According to the present invention, the amount of light can be measured even with an inexpensive optical sensor, making the overall device less expensive than conventional image processing methods using cameras, and it is possible to determine whether or not a rice ball has ingredients even while it is being transported at high speed.Even with a low-output light-emitting unit, by using monochromatic light, it is possible to measure a sufficient amount of inspection light concentrated in a narrow band with an inexpensive and compact device configuration, and it is possible to efficiently measure the scattering of the light irradiated onto the rice ball and the transmittance of the entire scattered light. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a front view of an onigiri ingredient shortage inspection device according to the present invention; [Figure 2] 1 is a side view of an onigiri ingredient missing inspection device according to the present invention; [Figure 3] 1 is a block diagram of a rice ball ingredient shortage inspection device according to the present invention. [Figure 4] 1 is an explanatory diagram showing how to inspect rice balls with ingredients using the rice ball ingredient shortage inspection device of the present invention. FIG. [Figure 5] 10 is a diagram showing inspection of rice balls without ingredients using the rice ball ingredient shortage inspection device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an onigiri ingredient shortage inspection device according to the present invention will be described in detail below with reference to the drawings.

[0016] [Rice ball missing ingredient inspection device 10] Fig. 1 is a front view of an onigiri ingredient shortage inspection device of the present invention. Fig. 2 is a side view of an onigiri ingredient shortage inspection device of the present invention. Fig. 3 is a block diagram of an onigiri ingredient shortage inspection device of the present invention. Fig. 4 is an explanatory diagram of inspecting onigiri with ingredients using an onigiri ingredient shortage inspection device of the present invention. Fig. 5 is a diagram of inspecting onigiri without ingredients using an onigiri ingredient shortage inspection device of the present invention.

[0017] As shown in the figure, the rice ball ingredient missing inspection device 10 of the present invention has a gap 16 between an upstream conveyor 12 and a downstream conveyor 14, which are formed by dividing a conveyor that transports rice balls 1 before they are formed and individually packaged, and is equipped with a light-emitting unit 20 arranged opposite the gap 16, which irradiates one narrow-band monochromatic light of visible light onto the rice balls 1 that pass through the gap 16, and a light sensor 30 that measures the amount of inspection light scattered inside the rice ball 1 and emitted from the backside, and a judgment unit 40 that judges whether the rice ball 1 has ingredients or not based on the amount of light of the inspection light.

[0018] The rice balls 1 of this embodiment are formed by adding ingredients 2 to a predetermined amount of rice using a forming machine in the upstream stage of the inspection device, and are in a state before being individually packaged by an individual packaging machine in the downstream stage. This is because if any ingredients are found to be missing during inspection after individual packaging, the film would be wasted. The ingredients 2 for the rice balls 1 are common, such as kelp, salmon, mustard greens, and plum.

[0019] The conveyor for rice balls 1 is located between the forming machine and the individual packaging machine in the production line. In this embodiment, the conveyor is divided into two: an upstream (forming machine side) conveyor 12 and a downstream (individual packaging machine side) conveyor 14. The upstream conveyor 12 and downstream conveyor 14 are arranged in series, with a gap 16 of approximately 5 to 20 mm, preferably 10 mm, between them. Onigiri ingredient missing inspection devices 10 are located above and below this gap 16. In this embodiment, a light-emitting unit 20 is located above the gap 16, and a light sensor 30 is located below. Alternatively, a configuration in which the light sensor 30 is located above and the light-emitting unit 20 is located below may also be used. Furthermore, by measuring the light intensity in the gap 16, the device width can be reduced to several tens of millimeters, thereby saving space overall and enabling easy installation in existing facilities.

[0020] The light-emitting unit 20 is an LED element that emits a single narrow-band monochromatic light in the visible light spectrum. The moisture content of rice balls is 55% to 65%, and due to the relationship between the absorption coefficient of water and wavelength, water strongly absorbs ultraviolet light in the ultraviolet region, which is undesirable. Furthermore, in the near-infrared region, absorption at specific wavelengths is prominent. On the other hand, in the visible light region, many wavelengths of visible light are relatively easily transmitted. For this reason, the light-emitting unit 20 is configured to emit visible light.

[0021] According to the specifications for power LEDs that emit monochromatic light, the wavelength range in which the brightness of the emission spectrum of an LED that emits red light at 625 nm is halved is 610 nm to 635 nm, within a range of ±15 nm, and the wavelength range in which the brightness of the emission spectrum of an LED that emits green light at 525 nm is halved is 500 nm to 550 nm, within a range of ±25 nm.In this invention, light sources such as these, in which the spectral brightness is halved within a range of ±30 nm of the emission wavelength, are referred to as monochromatic narrowband light sources.

[0022] Specifically, the light-emitting unit 20 is configured with an LED element with a wavelength of 525 nm or 625 nm. Even with low output, this type of light-emitting unit 20 emits narrow-band monochromatic light, concentrating the irradiated inspection light within a narrow wavelength range, enabling a sufficient amount of inspection light to be emitted for only wavelengths advantageous for inspection. In the process of selecting the visible light to be irradiated by the light-emitting unit 20, optimal inspection results were obtained with a wavelength of 530 nm when the ingredient was kelp. Optimal inspection results were obtained with a wavelength of 650 nm when the ingredient was salmon. Optimal inspection results were obtained with a wavelength of 480 nm when the ingredient was takana (green mustard greens). Thus, each ingredient has an optimal wavelength. The inventors found that when the light-emitting unit 20 used a green LED element with a wavelength of 525 nm, the difference in the amount of re-emission of inspection light between the presence and absence of ingredients was large. The optimal wavelength of inspection light for different ingredients has a large effect on the color of the ingredients, so it would be ideal to select a longer wavelength for warm-colored ingredients such as salmon or pickled plum, and a shorter wavelength for green ingredients such as takana. However, considering the convenience of the inspection device and the need for an inspection device that does not require switching or replacing light sources, 525 nm was selected as a wavelength that provides sufficient performance to distinguish between good products and defective products for salmon, pickled plum, and takana, and it was confirmed that this is fully viable as an inspection device that can determine the presence or absence of all ingredients.

[0023] Furthermore, the light-emitting unit 20 using a red LED element with a wavelength of 625 nm can provide better discrimination performance between good products and defective products due to missing ingredients than when a green light source is used for warm-colored ingredients such as salmon and pickled plums, so if the rice balls to be manufactured are limited to warm-colored ingredients, red light with a wavelength of 625 nm can be selected as the light source. In addition, a condenser lens 22 is provided in front of all the power LEDs for the light source so that the inspection light is irradiated only onto the surface of the rice ball 1. A condenser lens 22 with a focal angle of 15 degrees is selected for the condenser lens 22, and even if the assumed maximum distance from the surface of the lens to the surface of the rice ball 1 is 50 mm, the maximum diffusion range of the inspection light on the surface of the rice ball 1 is limited to a diameter of 27 mm, thereby achieving efficient irradiation of the inspection light onto the surface of the rice ball 1. The inventors conducted experiments on the performance of rice balls for detecting missing ingredients as a function of the wavelength of the inspection light, comparing the output current ratio of the optical sensor for defective products with those that are missing compared to non-defective products. The results showed that, while infrared light was absorbed by the moisture in the rice balls, making inspection impossible, red light produced a 5-fold increase in the optical sensor current ratio for defective products compared to non-defective products, and green light produced a 12-fold increase. Further experiments using shorter wavelengths revealed that blue light produced a 3-fold increase, and ultraviolet light produced no difference in the current between non-defective and non-defective products. Based on these data, green light (525 nm) and red light (625 nm) were selected as the wavelengths of the inspection light.

[0024] The optical sensor 30 is a sensor that uses a photo IC diode. When light strikes the optical sensor 30, it absorbs the light energy and generates a current. This current is proportional to the intensity of the light, is amplified by an amplifier circuit built into the photo IC diode, and is output as a voltage signal. In this embodiment, the optical sensor 30 is placed with a gap between it and the rice ball 1, without making contact with it. The optical sensor 30 receives the inspection light that is scattered inside the rice ball 1 and passes through it, and measures the amount of light.

[0025] Furthermore, when measuring the test light re-emitted from the back surface of the rice ball 1, the scattered test light is re-emitted from the entire back surface of the rice ball 1. Therefore, in order to obtain a good signal-to-noise ratio, it is important for the optical sensor 30 to integrate the amount of re-emitted test light emitted from the entire back surface of the rice ball 1. Therefore, in this embodiment, one optical sensor 30 is arranged, or multiple optical sensors 30 are arranged in parallel along the gap 16, depending on the size of the rice ball 1. With this configuration, when the rice ball 1 is small (for example, less than 40 mm in diameter), it is not necessary to capture the test light over a wide area. Since the outer shape of the bonito ball 1 is small and there are many areas that cannot completely block the direct light from the light-emitting unit 20, only one optical sensor 30 is arranged. When the rice ball 1 is large, the direct light from the light-emitting unit 20 can be sufficiently blocked, so multiple optical sensors 30 are arranged along the gap 16 to efficiently capture and sum the light scattered and transmitted inside the rice ball 1. This improves the accuracy of the light amount measured, making it possible to measure even small amounts of light. For example, in the case of a rice ball of about 80 mm, good inspection accuracy can be obtained by arranging two optical sensors 30.

[0026] An optical filter 32 is disposed on the surface of the optical sensor 30. The optical filter 32 is selected to be the same color as the monochromatic light emitted by the light-emitting unit 20 or the color of the rice ball ingredients, thereby increasing the transmittance of the inspection light of the same color. Such an optical filter 32 allows the inspection light to easily pass through, preventing the influence of various wavelength components of external light and improving the accuracy of light quantity measurement by the optical sensor 30.

[0027] The judgment unit 40 judges whether the rice ball 1 has ingredients based on the light intensity measured by the optical sensor 30. Here, the voltage signal corresponding to the light intensity measured by the optical sensor 30 has high-frequency noise removed by a high-frequency noise filter 42 on the circuit board. Then, noise derived from the commercial AC power supply is removed by a noise filter 46 and the signal is input to the judgment unit 40. When multiple optical sensors 30 are used, the voltage signals are summed. The judgment unit 40 then sets the light intensity measurement value of a non-defective rice ball with ingredients set to a preset value, and judges a rice ball with a high light intensity as defective.

[0028] [Effect] The operation of the rice ball ingredient missing inspection device 10 of the present invention, configured as described above, is described below. As the rice ball 1 passes through the gap 16 during transport, it is irradiated with a single narrow-band monochromatic light of visible light from the light-emitting unit 20. The inspection light is scattered within the rice ball 1, with almost no direct propagation. The inspection light is scattered by the white rice and diffuses throughout the rice ball 1. The light sensor 30 measures the amount of inspection light emitted from the back surface of the rice ball (the side opposite the irradiated surface). The judgment unit 40 compares the rice ball 1 with a non-defective product containing ingredients to determine whether the rice ball 1 contains ingredients. As shown in Figure 4, in the case of a non-defective product containing ingredients, the transmission path of the scattered inspection light is blocked by the ingredients, narrowing the transmission path of the scattered inspection light and lengthening the transmission path around the ingredients. As a result, the amount of scattered inspection light within the rice ball 1 is reduced, and the inspection light re-emitted from the back surface of the rice ball 1 is weakened, resulting in a judgment of a non-defective product. On the other hand, in the case of a defective product with no filling, as shown in Figure 5, the entire rice ball 1 is filled with rice grains (medium) that can scatter and transmit the inspection light, resulting in highly efficient scattering and transmission of the inspection light, and the inspection light re-emitted from the back of the rice ball 1 is strong, and compared to a good product with filling, the inspection light is stronger and the product is determined to be defective.

[0029] (Variation) On rice ball production lines, there is a variety of light emitted from lighting such as fluorescent lamps, surrounding image inspection machines, etc. For example, in the case of fluorescent lamps, light modulated by fundamental or harmonic components resulting from commercial frequencies of 50 Hz or 60 Hz, or in the case of inverter fluorescent lamps, light modulated by the inverter switching frequency, may reach the optical sensor 30. The present invention is provided with a changeover switch (changeover unit) 50 that changes the configuration of the light-emitting unit 20 to illuminate constantly, flash, or in pseudo-random pulse flashing.

[0030] If the rice ball is thick, the path along which the light is scattered and transmitted inside the rice ball 1 becomes longer, and the intensity of the re-emitted inspection light becomes smaller, so the light emitting unit 20 is set to be constantly lit. When the light source of external light that interferes with the inspection is a direct current light without being modulated, such as an incandescent lamp, the system is configured to simply blink at a fixed cycle and evaluate the difference in the inspection light intensity, which is synchronized with the blinking of the light-emitting unit, by periodically increasing or decreasing the amount of light received by the optical sensor 30 when the light is blinked. This configuration can reduce the interference with inspection performance caused by direct current external light.

[0031] When the external light is 50 Hz or 60 Hz, or is driven at high frequency by an inverter, if the periodic blinking cycle of the inspection light and the blinking of the external light cause beat interference (a disturbance in which two signals of different frequencies overlap, creating a periodically fluctuating pattern (beat)), the periodic fluctuation cannot be expected to mitigate the disturbance, so the beat interference can be mitigated by using blinking with pseudo-random pulses. In order to synchronize the voltage signal of the optical sensor 30 with the blinking of the light emitting unit 20 or the blinking caused by pseudo-random pulses, a synchronous detection unit 44 is provided between the high frequency noise filter 42 and the noise filter 46 .

[0032] According to the present invention, the amount of light can be measured even with an inexpensive optical sensor, making the overall device less expensive than conventional image processing methods using cameras. Furthermore, even with a low-output light-emitting unit, by using monochromatic light, a sufficient amount of inspection light concentrated in a narrow band of wavelengths can be measured with an inexpensive and compact device configuration, and the scattering of the light irradiated onto the rice ball and the transmittance of the entire scattered light can be measured efficiently.

[0033] Furthermore, food production lines are required to be faster and produce more per unit time every day, but this device can provide good measurement results even at a conveying speed of 100 m / min and product intervals of 10 mm. This is largely due to the fact that it uses a light sensor to determine the amount of light, rather than the conventional image processing method. In this embodiment, the object to be inspected is described as rice balls, but it is not limited to this and may be other water-containing starchy foods such as rice balls with a moisture content of 55% to 65%, for example, steamed buns with a moisture content of 30% to 40%, or bread with a moisture content of 30% to 45%.

[0034] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made without departing from the spirit and scope of the present invention. Furthermore, the present invention is not limited to the combinations shown in the embodiments, but can be implemented in various combinations. [Explanation of symbols]

[0035] 1 rice ball 2. Ingredients 10 Onigiri ingredient missing inspection device 12 Upstream conveyor 14 Downstream conveyor 16 Gap 20 Light-emitting part 22 Condenser lens 30 Light Sensor 32 Optical Filters 40 Judgment section 42 High frequency noise filter 44 Synchronous detection section 46 Noise Filter 50 Changeover switch

Claims

1. This rice ball ingredient shortage inspection device is characterized by having a gap between an upstream conveyor and a downstream conveyor, which are formed by dividing a conveyor that transports rice balls before they are formed and individually packaged, and has two light-emitting units arranged opposite each other above and below the gap, which irradiate the rice balls passing through the gap with a narrowband monochromatic light of any one of visible light, and a light sensor that measures the amount of inspection light scattered inside the rice ball and emitted from the backside, and a judgment unit that judges whether the rice ball has ingredients or not based on the amount of inspection light.

2. 2. The rice ball ingredient shortage inspection device according to claim 1, The device for inspecting rice balls for missing ingredients is characterized in that the light emitting unit is an LED element with a wavelength of 525 nm or 625 nm.

3. 2. The rice ball ingredient shortage inspection device according to claim 1, The optical sensor is characterized in that an optical filter of the same color as the monochromatic light emitted by the light-emitting unit or the color of the rice ball ingredients is arranged on the sensor surface.

4. The rice ball ingredient shortage inspection device according to any one of claims 1 to 3, The onigiri ingredient shortage inspection device is characterized in that one optical sensor is placed in the gap, or multiple optical sensors are placed in parallel along the gap.

5. 5. The rice ball ingredient shortage inspection device according to claim 4, The light-emitting unit emits a monochromatic light in a flashing manner, and the optical sensor measures the amount of light synchronized with the flashing of the light-emitting unit.

6. 5. The rice ball ingredient shortage inspection device according to claim 4, The light-emitting unit emits monochromatic light in a flashing pseudo-random pulse, and the optical sensor measures the amount of light synchronized with the flashing pseudo-random pulse of the light-emitting unit.

Images