JP7237317B2 - Color temperature variable lighting device - Google Patents

Description

The present invention relates to a variable color temperature illumination device capable of varying the color temperature of illumination light, and more particularly to a color temperature variable illumination device that measures the color of ambient light and emits light in a complementary color corresponding to the measured color to produce white light. The present invention relates to a variable color temperature illuminator that illuminates an object such as crops, fish and shellfish with a light source and makes the colors stand out so that even an amateur can easily identify or sort out the crop, fish and shellfish.

Since crops such as fruits and vegetables undergo photosynthesis, the sweetness and freshness of harvested products are closely related to the time of harvest. In general, it is decided whether to harvest in the morning or in the evening, taking into consideration these harvesting factors, daytime heat countermeasures, labor shortages, and effective use of time. Even under such circumstances, part-time farmers are engaged in other work other than agriculture during the daytime, so they cannot harvest crops during the daytime. Due to circumstances such as not being able to make it in time by work alone, there are cases where the harvest is done at night or early in the morning.

When harvesting at night, as shown in FIG. 1, a small working light 1 made of a light source such as an LED (Light Emitting Diode) is attached to the head to illuminate the crops 2 while harvesting. ing.

The color temperature of the ambient light and the light source of the work light poses a problem in the harvesting work during the hours other than the daytime. Harvest color is an extremely important factor in determining the optimal time to harvest. Judgment as to whether crops are ripe or immature for harvesting is usually made based on the size and color of the crops, so there is a risk of erroneous harvesting unless the crops are observed or identified with accurate color temperature. The color temperature is a scale (unit) that expresses the color of light emitted by a light source in a quantitative numerical value, and the thermodynamic temperature K (Kelvin) is used as the unit.

The color temperature at which humans can most accurately observe the color of an object such as crops is said to be 5600[K], but in the early morning, the color temperature is around 7000[K], with strong blue and red and yellow. looks weak. In addition, the color temperature is around 3500 [K] in the morning and evening, and red and yellow appear strong and blue appears weak. Most of the light sources for work lights used for harvesting at night are LEDs, and as a mechanism for emitting white light, a combination of a blue LED and a yellow phosphor, which is its complementary color, is used. Although this system has a simple structure and is efficient, it has spectral characteristics as shown in FIG. 2 and has low color rendering properties (Ra). Color rendering is an index that indicates how well colors are reproduced when natural light hits an object when illuminating it with a light or the like. The intensity is greatly attenuated in the wavelength range of about 460 to 530 nm. This means that it is difficult to see blue, yellow-green, and green objects, so it can be seen that it is not suitable for harvesting agricultural products.

Japanese Patent Application Laid-Open No. 2020-87286 JP 2013-226161 A JP 2012-85649 A JP 2007-135583 A

Conventionally, when judging the optimal time for harvesting crops, the color temperature of the ambient light is biased, especially in the early morning and in the morning and evening. I could be wrong.

In addition, although the general working light used for harvesting at night may look white, it actually has a large intensity attenuation range in a specific wavelength range, which causes workers to see the color of the crop. There was a risk of mis-harvesting due to misidentification. Furthermore, in harvesting at night, it is often difficult to distinguish specific crops from thick crops, which is one of the factors that reduce work efficiency.

The present invention has been made based on the circumstances as described above, and an object of the present invention is to measure the color of the ambient light, emit the complementary color, and additively mix the ambient light and the complementary color to produce white light. Colors that can change the color temperature of lighting so that workers can accurately judge the color of objects such as crops, and so that the appearance of specific colors can be emphasized by switching functions. An object of the present invention is to provide a temperature variable lighting device.

The present invention relates to a variable color temperature lighting device, and the above object of the present invention is to provide a color sensor for measuring the color of ambient light, four-color LEDs for illuminating an object, and a color signal from the color sensor to a predetermined value. It is composed of a chromaticity coordinate conversion unit that converts to a color space, a complementary color calculation unit that calculates a complementary color of the color space, and an LED correction unit that corrects the LED based on the complementary color and causes the LED to emit light. Compensation is an adjustment of the brightness of the LEDs, which is achieved by providing PWM control of the LEDs .

Further, the present invention relates to a color temperature variable lighting device, and the above object of the present invention is to provide four-color LEDs for illuminating an object and a color signal for converting a color signal wirelessly specified from a terminal into a predetermined color space. This is achieved by including a degree coordinate conversion unit and an LED correction unit that corrects the LED based on the color space and causes the LED to emit light.

According to the present invention, light is emitted in the complementary color of the color of the ambient light to obtain the color temperature of the white light with enhanced color rendering, so that the harvester can perform the harvesting and sorting operations of the crops without error. can. In addition, by specifying the same color as the target such as harvested products and irradiating the target with light emission in the specified color, even an amateur can easily identify or sort the target such as agricultural products, seafood, etc. Work efficiency can be improved.

It is a figure which shows a mode that it harvests using a light for work. FIG. 5 is a characteristic diagram showing an example of spectral characteristics of a conventional work light; 1 is an external view showing an example (headlight type) of a variable color temperature lighting device according to the present invention; FIG. FIG. 4 is an external view showing another example (headlight type) of the color temperature variable lighting device according to the present invention; FIG. 10 is an external view showing another example (flashlight type) of the variable color temperature lighting device according to the present invention; 1 is a block diagram showing a configuration example of an embodiment of the present invention; FIG. It is a chromaticity diagram in the CIE color system. FIG. 3 is a characteristic diagram showing an example of characteristics of RGB three-color LEDs; FIG. 3 is a characteristic diagram showing an example of characteristics of an RGBA four-color LED; It is a wiring diagram which shows an example of a PWM dimming circuit. It is a flowchart which shows the operation example (1st Embodiment) of this invention. FIG. 4 is a schematic diagram showing another embodiment of the present invention; FIG. 4 is a block diagram showing a configuration example of another embodiment of the present invention; It is a flowchart which shows the operation example (2nd Embodiment) of this invention.

The present invention is a lighting device capable of illuminating an object such as agricultural crops by emitting light with a color temperature according to the ambient light and the object. By emitting complementary colors, it is possible to obtain white light by additive color mixture, and it is a color temperature variable lighting device capable of emitting true white light without color bias.

In addition, the present invention can illuminate with true white light with a uniform wavelength by combining the light emission of the RGBA four-color LEDs, improving the color rendering properties and enabling the operator to accurately determine the color of the object. there is A four-color LED has three colors of red, green, and blue plus amber information called amber.

Furthermore, in harvesting at night, it is often difficult to distinguish specific crops among the overgrown crops, which is one of the factors that reduce the efficiency of harvesting work. By designating a color and emitting light, even a non-professional can easily identify or sort out target objects such as crops and seafood, thereby improving work efficiency.

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

FIG. 3 shows an example of the appearance of the variable color temperature lighting device 10 according to the present invention. An annular band 11 and a semicircular band 12 on the vertical plane are intersected. The bands 11 and 12 may be elastic bodies as long as the main body of the variable color temperature lighting device 10 can be attached to the head of the operator directly or via a hat. An optical unit 20 for projecting and receiving light, and an arithmetic processing unit 30 connected to the optical unit 20 for arithmetic processing are provided on the front surface of the variable color temperature lighting device 10 . Also, although not shown, a switch for turning ON/OFF the power of the variable color temperature lighting device 10 is appropriately provided, and a member for charging or replacing the built-in battery is also provided as appropriate.

The exterior structure of the variable color temperature lighting device 10 is not limited to that shown in FIG. 3, and as shown in FIG. can be With this structure, the operator can wear the variable color temperature lighting device 10 directly on the head without wearing a hat, and can prevent dust, dew, etc. from adhering to the hair.

3 and 4 are both headlight-type structures, a long flashlight-type structure as shown in FIG. 5 may be used. In this case, the operator holds the color temperature variable lighting device 10 in hand, illuminates it, determines the color of the crops, and harvests the crops after the determination.

The exterior structure of the variable color temperature lighting device 10 according to the present invention is shown in FIGS. Any structure that can illuminate the object with the calculated white light (additive color mixture) with high color rendering properties is sufficient, and the configurations of the optical unit 20 and the arithmetic processing unit 30 are the same in any case, and will be described below.

FIG. 6 shows a configuration example (first embodiment) of the present invention. An optical unit 20 includes a color sensor 21 that measures the color temperature of ambient light and four LEDs ( RGBA-LED 22 consisting of R, G, B, A). A color signal CS indicating the color of the ambient light measured by the color sensor 21 is input to an arithmetic processing section 30 comprising a CPU (Central Processing Unit), an MPU (Micro Processor Unit), etc., and the arithmetic processing section 30 outputs the color signal A chromaticity coordinate conversion unit 31 that converts CS into a color space CX to obtain a color space CX, a complementary color calculation unit 32 that calculates a complementary color from the coordinate-converted color space CX, and a complementary color CM calculated by the complementary color calculation unit 32. It is composed of an LED correction section 33 for correcting the characteristics of the actual LED light emission according to the characteristics, and a control section 35 for controlling the whole. The correction signal LS from the LED correction unit 33 is input to the RGBA-LED 22, and the light emitted by the RGBA-LED 22 according to the correction signal LS is irradiated as irradiation light to illuminate the crops.

The color sensor 21 is a sensor that measures the color (RGB) of ambient light, and is configured by combining three photodiodes corresponding to specific wavelengths (RGB). Although only the brightness can be measured with a single photodiode, by mounting three photodiodes and combining them with RGB color filters, the three primary colors can be obtained, and the color of the incident light can be specified from the ratio of the three primary colors. can be done. The incident light may be ambient light or reflected light, but ambient light is used in this embodiment. In order to prevent erroneous operation, it is necessary to take measures such as capturing ambient light when the color sensor does not emit light from the LED.

A chromaticity coordinate conversion section 31 in the arithmetic processing section 30 converts the color signal CS from the color sensor 21 into a color space CX, and the color space CX is a CIE RGB chromaticity coordinate system and a CIE XYZ chromaticity coordinate system. , CIE Lab chromaticity coordinate system, CIE Luv chromaticity coordinate system, CIE UVW chromaticity coordinate system, etc. Since the output color space from the color sensor 21 varies depending on the manufacturer and product, in order to unify the arithmetic processing, it is converted into a color space CX such as the CIE RGB chromaticity coordinate system or the CIE XYZ chromaticity coordinate system. The CIE RGB color space and the CIE XYZ color space were two defined by the International Commission on Illumination (CIE) in 1931. The CIE RGB color space is one of the RGB color spaces, and each primary color has a single wavelength. It has the characteristic of being light. FIG. 7 is a chromaticity diagram in the CIE color system, showing chromaticity mapped on the plane "x+y+z=1" as seen from the z-axis direction.

The complementary color calculation unit 32 applies a complementary color C (cyan) to the R (red) component of the color space CX, a complementary color M (magenta) to the G (green) component, and a complementary color of Y (yellow) to the B (blue) component. Calculate and output complementary color CM. Additive mixing of all the colors results in bright white. For example, if the R component of ambient light is 20%, the G component is 50%, and the B component is 30%, basically C=20%, M=50%, and Y=30% are mixed. This is equivalent to LED light emission of R=80%, G=50%, and B=70%, which results in additive color mixture with ambient light, resulting in white. However, in practice, it is also necessary to consider the characteristics of the device. The color sensor 21 measures colors with three photodiodes, but the light receiving wavelength range of the photodiodes themselves is much wider than the light emitting wavelength range of LEDs, and the three RGB photodiodes sufficiently cover the visible light region. can. On the other hand, since LEDs have a narrow emission wavelength range even if they are the same RGB, there are wavelengths that cannot cover the entire visible light region by themselves, and the missing wavelengths result in color bias. In order to improve this, in the present invention, an amber LED is added to the RGB-LEDs of the light emitting section 20. FIG. In this way, emitting the same color as measured by the RGB photodiode (color sensor 21) by the RGBA-LED 22 is complicated and cannot be represented by a simple formula, but the characteristics of each element are analyzed and converted. A lookup table is created for each color, and the complementary color calculation unit 32 and the LED correction unit 33 refer to the lookup table to perform complementary color-light emission conversion calculations.

As a method of creating a lookup table, a method of carefully comparing the characteristic diagrams of the photodiode and the LED and converting the combination of the RGBA-LEDs 22 capable of emitting light of the closest color to the light receiving characteristics of each of the RGB photodiodes into data. There is In this way, if the data of the RGBA-LED 22 corresponding to each color of the RGB photodiode can be created, by adjusting the output level of the RGBA-LED 22 according to the color ratio of the RGB photodiode, the illumination light of the same color as the ambient light can be obtained. is obtained.

The LED correction unit 33 matches the complementary color CM from the complementary color calculation unit 32 to the actual characteristics of the LED by referring to the lookup table. A matter to be taken into consideration by the LED correction unit 33 is that each color of the RGBA-LEDs 22 has a luminance difference. The color of the LED is determined by the elements that combine, and the difference in the elements also changes the brightness. In general, the brightness of R tends to be high, and the brightness of G tends to be low. It is also the LED correction unit 33 that corrects the luminance difference due to such LED colors.

The RGBA-LED 22 causes four LEDs (R, G, B, A) to emit light according to the correction signal LS from the LED correction unit 33, and illuminates the crops with white light having high color rendering properties.

Here, in order to obtain white light with high color rendering properties, there is known a method of combining three LEDs of the three primary colors RGB to emit light instead of a blue LED and a yellow phosphor. However, in an actual LED, the difference in luminance (intensity) of RGB is large and the wavelength interval between green (G) and red (R) is wide, so that the spectral characteristics are as shown in FIG. In the characteristic diagram of FIG. 8, the wavelength region of about 540 to 620 nm is greatly attenuated, which means that yellow and orange objects are difficult to see, and cannot be said to be true white light.

Therefore, in the present invention, an A (amber) LED (585 nm to 595 nm) is added between GR and LEDs of the four primary colors RGBA whose intensity is adjusted are made to emit light. As a result, a spectral characteristic with uniform intensity and no large attenuation region as shown in FIG. 9 can be obtained, and it is possible to irradiate with true white light that eliminates the difficulty of seeing yellow and orange objects.

It is efficient to use PWM (Pulse Width Modulation) of about 1 KHz for the LED dimming, in which the respective RGBA LEDs are individually dimmed to equalize the relative intensity, using afterimages of the eyes. FIG. 10 shows an example of a dimming circuit, in which resistors RR, GR, BR, and A are connected to RGBA LEDs (R-LED, G-LED, B-LED, and A-LED), respectively. -R and R-FET, G-FET, B-FET, and A-FET as switching elements are connected in series, and each FET receives PWM signals R-PWM, G-PWM, and B from the control unit 35, respectively. - PWM, A - ON (1)/OFF (0) by PWM. When the R-FET, G-FET, B-FET and A-FET are turned ON, the corresponding R-LED, G-LED, B-LED and A-LED emit light. Therefore, the ON time of each FET can be adjusted by pulse width modulation of the PWM signals R-PWM, G-PWM, B-PWM and A-PWM, and the light emission of R-LED, G-LED, B-LED and A-LED can be adjusted. Since the time can be adjusted, the relative intensity of each LED can be matched.

The RGBA-LED 22 receives the correction signal LS, which is each output value (current value) of the RGBA-LED 22 whose brightness has been corrected, from the LED correction unit 33, and converts it to the PWM pulse width (duty ratio) via the control unit 35. After conversion, the RGBA-LED 22 emits light with a PWM signal. As described above, the complementary colors (CMY) are not emitted as they are, but are emitted after being converted into equivalent primary colors (RGB). Although PWM is a digital system, an analog quantity can be expressed by a duty ratio, that is, a time ratio between ON and OFF. Although it is a digital system, the idea is that if ON/OFF is repeated in a short period of time, it will be averaged and eventually become equal to the analog quantity. For example, if the PWM frequency is 1 KHz (=period 1 ms) and R=80% light emission is desired, the R-PWM ON time is 0.8 ms and OFF time is 0.2 ms. Similarly, to emit light with G=50%, the ON time of G-PWM should be 0.5 ms, and the OFF time should be 0.5 ms.

FIG. 11 shows an operation example of the present invention (first embodiment). First, the color of ambient light is measured by the color sensor 21, and the color signal CS of the measured color is input to the chromaticity coordinate conversion unit 31 ( step S10). The chromaticity coordinate converter 31 converts the input color signal CS into the color space CX, and the color space CX is input to the complementary color calculator 32 (step S11). The complementary color calculation unit 32 calculates the complementary color CM according to the color space CX, and the complementary color CM is input to the LED correction unit 33 (step S12).

In the LED correction section 33, brightness adjustment is performed via the control section 35 (step S13), and a current value for emitting light from the RGBA-LED 22 is calculated (step S14). The calculated current value is calculated into the duty ratio of the PWM signal by the control unit 35 or the LED correction unit 33 (step S15), and the RGBA-LED 22 is PWM-controlled according to the calculated duty ratio (step S16).

Next, a variable color temperature lighting device (second embodiment) capable of emitting light of a specified color and making crops of a specific color look bright will be described. In the above-described first embodiment, the color of the ambient light is measured, and the LED is emitted so as to be an additive color mixture with respect to the measured value, and the color is changed to white. The user is asked to specify a color on the terminal, and by emitting LED light in the same color as the specified color, the crops are made to appear brighter.

With the labor shortage becoming a problem, working efficiency will be greatly improved if even amateurs can easily identify or sort objects such as agricultural products and seafood. In order to realize this, as shown in FIG. 12, the worker first selects and designates a specific color from the color sample displayed on the screen of the smartphone 40, and selects and designates the color of the crops that the worker wants to make stand out. data is transmitted to the variable color temperature lighting device 10A by wireless communication, and the lighting device 10A illuminates with the designated color. This allows crops to appear brighter with a specific color specified.

FIG. 13 shows an example of such a configuration. A smartphone 40 is provided with a color sample 41, and from the color sample 41 displayed on the screen, a specific color that makes crops look bright is specified. The designated color signal CD is input to the chromaticity coordinate conversion unit 31 in the arithmetic processing unit 30A of the color temperature variable lighting device 10A via wireless communication such as Bluetooth (registered trademark), and converted into a color space corresponding to the color signal CD. Converted to CXA. The color space CXA is input to the LED correction unit 34 and corrected, and the RGBA-LED 22 emits light according to the corrected correction signal LSA. Since the RGBA-LED 22 emits light at the color temperature specified by the smartphone 40 in consideration of the ambient light, it is possible to make the crops to be conspicuous appear brighter.

FIG. 14 shows an operation example of the present invention (second embodiment). First, a color is designated by the smartphone 40, and the color signal CD of the designated color is input to the chromaticity coordinate conversion section 31 (step S20). . The chromaticity coordinate conversion unit 31 converts the input color signal CD into the color space CXA, and the color space CXA is input to the LED correction unit 34 (step S21). In the LED correction unit 34, luminance adjustment is performed via the control unit 35 (step S22), and a current value for emitting light from the RGBA-LED 22 is calculated (step S23). The calculated current value is calculated into the duty ratio of the PWM signal by the control unit 35 or the LED correction unit 34 (step S24), and the RGBA-LED 22 is PWM-controlled according to the calculated duty ratio (step S25).

Here, the smartphone 40 is used to specify the color, but it is also possible to use another tablet terminal. It is also possible to make

In addition, although agricultural products have been described above, the present invention is also applicable to the field of sorting and discriminating target objects such as seafood and mushrooms.

Moreover, although the method of reading the color temperature of ambient light with a color sensor (RGB photodiode) is used in the above description, it is also possible to perform a similar operation with an RGB camera. In this case, instead of taking the ambient light directly into the RGB camera, a gray card (gray with no color bias = neutral color card) is placed near the object, and the gray card is imaged with the RGB camera, The color temperature of ambient light may be read from the RGB values. The difference is between a color sensor that directly receives ambient light and an RGB camera that receives reflected light of the ambient light, but the principle is the same.

1 work light 2 crops 10, 10A color temperature variable lighting device 11, 12 band 13 cap 20 optical unit 21 color sensor 22 RGBA-LED
30, 30A Arithmetic processing unit 31 Chromaticity coordinate conversion unit 32 Complementary color calculation unit 33, 34 LED correction unit 35 Control unit 40 Smartphone 41 Color sample

Claims (4)

a color sensor that measures the color of ambient light;
four-color LEDs that illuminate the object;
a chromaticity coordinate conversion unit that converts the color signal from the color sensor into a predetermined color space;
a complementary color calculation unit that calculates a complementary color of the color space;
an LED correction unit that corrects the LED based on the complementary color and causes the LED to emit light;
consists of
The color temperature variable lighting device , wherein the correction of the LED is adjustment of the luminance of the LED, and the LED is PWM-controlled . The four color LEDs are R (red), G (green), B (blue) and A (amber), and the color space is CIE RGB chromaticity coordinate system, CIE XYZ chromaticity coordinate system, CIE Lab chromaticity 2. The variable color temperature lighting device according to claim 1 , wherein the coordinate system is one of the coordinate system, the CIE Luv chromaticity coordinate system, and the CIE UVW chromaticity coordinate system. 3. The variable color temperature lighting device according to claim 1 or 2, wherein the lighting device is of a headlight type which is entirely mounted on the head and performs the color measurement and the illumination by the LED. 3. The variable color temperature lighting device according to claim 1, wherein the lighting device is of a flashlight type that is held in a hand and performs the color measurement and the lighting with the LED.

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