JP2008186627A - Lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately control the color of emitted light regardless of changes in ambient temperatures by compensating detected output variations by temperature characteristics of a light quantity sensor, and to reduce the cost of a lighting system by dispensing with a temperature sensor. <P>SOLUTION: This lighting system 1 is equipped with a light quantity sensor part 5, a memory part 6, a temperature estimating part 71, and a correction part 72, The memory part 6 memorizes a first table for estimating the ambient temperatures, and a second table showing a relation between the ambient temperatures and correction values almost equal to the detected output variations by the temperature characteristics of the light quantity sensor part 5. Since the temperature estimating part 71 estimates the ambient temperature on reference to the first table, no temperature sensor is required, and the cost reduction can be attained. In addition, since the correction part 72 refers to the second table, and corrects the detected output by using the correction value corresponding to the estimated ambient temperature, the detected output variations by the temperature characteristics of the light quantity sensor 5 can be compensated. Accordingly, color temperatures of emitted light can be highly accurately controlled regardless of changes in the ambient temperatures. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illuminating device in which the light emission amount of a light emitting diode is feedback-controlled based on a detection output of a light quantity sensor and has a temperature compensation function.

  2. Description of the Related Art Conventionally, as a lighting device that produces a wall surface of a building or illuminates a park or the like, a light source composed of a light emitting diode (hereinafter referred to as LED) is known. This illuminating device has, for example, a red LED, a green LED, and a blue LED, and emits synthetic light such as white by adjusting the light emission amount of these LEDs. For example, in order to obtain white combined light, the LEDs of the respective colors need to emit light with an equal amount of light. However, due to an error due to the temperature characteristic of the LED, the light emission amount of each color LED may vary. In this case, the chromaticity of the white light that is the combined light changes, and a difference occurs between the desired chromaticity and the actual chromaticity.

  Therefore, as an illuminating device configured to obtain light of desired chromaticity with high accuracy, light emission including a plurality of types of first red LEDs and second red LEDs of the same color system having different peak wavelengths, and a spectrum sensor. An apparatus is known (see, for example, Patent Document 1). This light-emitting device measures the peak wavelength of each LED that changes with a change in environmental temperature with a spectrum sensor even when the environmental temperature changes, and adjusts the emission ratio of each LED based on the peak wavelength of each LED By doing so, the peak wavelength of the synthesized spectrum obtained by synthesizing the spectrum of each LED is brought close to the target value.

  In addition, the lighting device includes a drive control unit that drives the LED by supplying a current and a light amount sensor that measures a light amount of each color included in the combined light of the LED. A backlight device is known that feedback-controls the current amount of each color LED based on the detection output of a light quantity sensor so that light has a predetermined chromaticity (see, for example, Patent Document 2). The backlight device further includes a temperature sensor that detects the temperature of the LED, and storage means that stores an initial current amount of each color LED and a correction amount corresponding to the temperature of the initial current amount. When the power is turned on, the drive control unit calculates a correction amount based on the detection value of the temperature sensor, adds the calculated correction amount to the initial current amount of each color LED, and activates each color LED with the corrected initial current amount. . According to this apparatus, regardless of the temperature when the power is turned on, the time required to converge to a predetermined chromaticity immediately after the power is turned on is shortened.

However, in the light emitting device and the backlight device described above, no measures are taken against detection output change due to temperature characteristics of a spectrum sensor and a light amount sensor (hereinafter referred to as a light amount sensor or the like). Therefore, the feedback control of the LED is performed according to the detection output of the light quantity sensor or the like. Therefore, when the detection output of the light quantity sensor or the like changes with the ambient temperature change, an error occurs, and the combined light of the LED, that is, the emitted light of the device It was difficult to control the color of the high-precision. In addition, as in the above backlight device, in order to control the color of the synthesized light with high accuracy, even if the detection output of the light amount sensor is corrected based on the temperature information of the temperature sensor, a temperature sensor is necessary. It was difficult to reduce the cost.
JP 2006-253502 A JP 2006-171893 A

  The present invention has been made to solve the above-described conventional problems, and compensates for changes in detection output due to the temperature characteristics of the light quantity sensor, so that the color of emitted light can be controlled with high accuracy regardless of ambient temperature changes. An object of the present invention is to provide a lighting device that can reduce the cost by eliminating the need for a temperature sensor.

  In order to achieve the above object, the invention of claim 1 is directed to a light emitting diode, a light amount sensor that detects light from the light emitting diode and measures the amount of light, and based on a detection output of the light amount sensor. And a control unit that feedback-controls the amount of light emission, wherein the detection output of the light amount sensor when the light emitting diode is controlled to emit light at a reference light emission amount is the detection output at a predetermined ambient temperature. As a reference value, a first table showing the relationship between the change from the reference value according to the ambient temperature and the ambient temperature, and a relationship between the ambient temperature and the correction value for correcting the detected detection output. 2, and the correction value is a value substantially equal to a change in detection output due to the temperature characteristics of the light quantity sensor. A change amount between the detection output of the light amount sensor and the reference value when the light emitting diode is controlled to emit light with a reference light emission amount is calculated, and the first table is calculated based on the calculated change amount. The ambient temperature is referred to, the correction value corresponding to the estimated ambient temperature is acquired with reference to the second table, and the acquired correction is performed to obtain a desired amount of light. While correcting the detection output using a value, the light emission amount of the light emitting diode is feedback-controlled based on the corrected detection output.

  According to a second aspect of the present invention, in the illumination device according to the first aspect, the control unit calculates a change between the detection output of the light quantity sensor and the reference value after the operation of the light emitting diode is stabilized. It is.

  According to a third aspect of the present invention, in the illumination device according to the first or second aspect, the light emitting diode includes a red light emitting diode, a green light emitting diode, and a blue light emitting diode.

  According to the first aspect of the present invention, since the control unit estimates the ambient temperature with reference to the first table, a temperature sensor for temperature compensation becomes unnecessary. For this reason, cost can be reduced. Further, the storage unit stores a second table indicating a relationship between the ambient temperature and a correction value that is substantially equal to a change in the detection output due to the temperature characteristic of the light quantity sensor, and the control unit sets the estimated ambient temperature to the estimated ambient temperature. Since the detection output is corrected using the corresponding correction value, a change in the detection output due to the temperature characteristic of the light quantity sensor can be compensated. For this reason, the color of the emitted light of the apparatus can be controlled with high accuracy regardless of the ambient temperature change.

  According to the invention of claim 2, it is possible to accurately calculate the change between the actual detection output and the reference value. Therefore, based on this change, the ambient temperature can be estimated with high accuracy by the control unit. Therefore, the detection output can be corrected according to the ambient temperature estimated with high accuracy. As a result, it is possible to perform highly accurate feedback control on the light emission amount of the light emitting diode using the corrected detection output.

  According to the invention of claim 3, light of all colors can be emitted by controlling the light emission amount for each of the red light emitting diode, the green light emitting diode, and the blue light emitting diode.

  Hereinafter, an illumination device according to an embodiment of the present invention will be described with reference to the drawings. FIG.1 and FIG.2 shows the electrical structure of the illuminating device which concerns on this embodiment, and the information which the memory | storage part of this illuminating device memorize | stores. The lighting device 1 includes a light emitting unit 3 having a light emitting diode (hereinafter referred to as an LED) 2, a lighting circuit unit 4 configured by an electric circuit that lights the LED 2, and detects the light from the LED 2 and measures the amount of light. And a storage unit 6 that stores the temperature characteristics of the LED 2 and the light amount sensor unit 5.

  Further, the lighting device 1 refers to the data in the storage unit 6 to estimate the temperature of the light amount sensor unit 5 and to transmit the dimming signal to the lighting circuit unit 4 to control the light emission amount of the LED 2. And a power supply unit 8 for supplying power to the above-described units. The control unit 7 feedback-controls the light emission amount of the LED 2 based on the detection output of the light amount sensor unit 5. The power supply unit 8 may be configured by a battery or may be configured to supply power from a commercial power supply to each unit of the lighting device 1. In the present embodiment, for example, color temperature is used to quantitatively express the light color. Hereafter, each part of the illuminating device 1 is demonstrated in detail.

  The LED 2 includes a red LED 2r, a green LED 2g, and a blue LED 2b. The light emission amount of the LED 2 is PWM controlled by the control unit 7. In the light emitting unit 3, the red LED 2r, the green LED 2g, and the blue LED 2b are arranged in a lump, and a plurality of these lumps are arranged one-dimensionally, two-dimensionally, or three-dimensionally. The combined light of the light emitted from the LEDs 2r, 2g, and 2b of each color becomes the light emitted from the light emitting unit 3. The emitted light can be set to all colors by controlling the light emission amounts of the red LED 2r, the green LED 2g, and the blue LED 2b, respectively. For example, when the light emission amounts of the red LED 2r, the green LED 2g, and the blue LED 2b are substantially equal, the light emitted from the light emitting unit 3 is white light. The number and arrangement of the red LED 2r, the green LED 2g, and the blue LED 2b are not limited to the form illustrated in FIG.

  The light amount sensor unit 5 is configured to be able to measure the respective light amounts of red light, green light, and blue light included in the light emitted from the light emitting unit 3. For example, the light amount sensor unit 5 includes a red filter 51r that transmits red light, a green filter 51g that transmits green light, and a blue filter 51b that transmits blue light in order to measure the light amount of each color light. . The red filter 51r separates the red component from the light emitted from the light emitting unit 3, and similarly, the green filter 51g and the blue filter 51b separate the green component and the blue component from the combined light. A plurality of light quantity sensors 52r, 52g, and 52b are disposed behind the filters 51r, 51g, and 51b for the respective colors. These light quantity sensors 52r, 52g, and 52b measure the light quantity of each color light that has been dispersed. The light amount sensor unit 5 calculates the color temperature of the emitted light from the light emitting unit 3 based on the measured light amount of each color light, and sends this color temperature information to the control unit 7 as a detection output.

  The storage unit 6 is configured by a memory such as a ROM or a RAM, and the memory emits the color temperature of the emitted light of the light emitting unit 3 and the red light, the green light, and the blue light necessary to generate the light of the color temperature. A color temperature table indicating a correspondence relationship with the amount of light is stored. The color temperature set in this color temperature table includes the reference color temperature, and this reference color temperature is a reference for obtaining the change when the color temperature changes according to the ambient temperature. Is the color temperature. Here, the amount of light set to the LED 2 of each color in order to emit the combined light of the reference color temperature is referred to as the reference light emission amount of the LED 2. The storage unit 6 controls the dimming control so that the LED 2 emits light with the reference light emission amount at the predetermined ambient temperature, that is, the light amount when the light emission amount of the LED 2 is controlled with the reference light emission amount as a target value. The detection output of the sensor unit 5 is stored. Hereinafter, this detection output is referred to as a reference detection output (reference value). The reference detection output is a reference for obtaining the change when the detection output changes according to the ambient temperature.

Furthermore, the memory | storage part 6 has memorize | stored two tables with said memory. Among these tables, one of the tables is a change in the detection output of the light amount sensor unit 5 when the dimming control is performed so that the LED 2 emits light with the reference light emission amount, and the change amount corresponding to the ambient temperature from the reference detection output. It is the 1st table 61 (1st table) which shows the relationship with temperature. This change in the detection output corresponds to the change in the light emission amount when the light emission amount is changed due to the ambient temperature due to the temperature characteristic of the LED 2 when the light control is performed so that the LED 2 emits light with the reference light emission amount. This is a total value of the change amount of the detection output of the light amount sensor unit 5 that changes and the change amount of the detection output that changes due to the ambient temperature due to the temperature characteristics of the light amount sensor unit 5. That is, the change in the detection output indicates the difference between the actual detection output and the reference detection output when the dimming control is performed so that the LED 2 emits light with the reference light emission amount. The above total value is derived in advance by experiments or calculations. An example of the first table 61 in FIG. 2 and is shown, ambient temperatures T ₁ corresponds to the change in E ₁ detection output, also the ambient temperature T ₂ is set corresponding to the change in E ₂ ing.

The other of the two tables is a second table 62 (second table) showing the relationship between the ambient temperature and a correction value for correcting the detection output changed from the reference detection output. This correction value is controlled by dimming control so that the LED 2 emits light with the reference light emission amount, and changes depending on the temperature characteristics of the light quantity sensor unit 5 alone when the actual ambient temperature is the ambient temperature corresponding to the correction value. It is approximately equal to the change in detection output. That is, this change indicates a difference from the reference detection output. Since the temperature characteristic of the light quantity sensor unit 5 is substantially linear, it is easy to make a table. In addition, the correction value is derived in advance by experiment or calculation. An example of the second table 62 in FIG. 2 and is shown, the correction value C ₁ in response to the ambient temperature T ₁ is also the correction value C ₂ in response to the ambient temperature T ₂ is set. The ambient temperature in the first and second tables 61 and 62 is preferably a temperature zone.

  The control unit 7 is composed of a microcomputer equipped with a CPU. The control unit 7 includes a temperature estimation unit 71 that estimates the ambient temperature, a correction unit 72 that corrects the detection output of the light amount sensor unit 5 based on the estimated ambient temperature information sent from the temperature estimation unit 71, and the correction. The lighting control unit 73 generates a dimming signal based on the detection output and sends the dimming signal to the lighting circuit unit 4.

  The temperature estimation unit 71 reads the reference detection output of the light amount sensor unit 5 from the storage unit 6, compares the reference detection output with the actual detection output of the light amount sensor unit 5, that is, the measured value, and calculates the change amount of the detection output. To do. Furthermore, the temperature estimation unit 71 reads the ambient temperature corresponding to the calculated change amount with reference to the first table 61 of the storage unit 6. The read ambient temperature is estimated to an actual ambient temperature by the temperature estimation unit 71. The temperature estimation unit 71 sends the estimated ambient temperature information and the detection output of the light amount sensor unit 5 to the correction unit 72.

  Based on the estimated ambient temperature information from the temperature estimation unit 71, the correction unit 72 reads the correction value corresponding to the estimated ambient temperature with reference to the second table 62 of the storage unit 6, and acquires it. This correction value is expressed in color temperature. Further, the correction unit 72 corrects the detection output of the light amount sensor unit 5 using the correction value. In this correction, for example, a correction value is added to or subtracted from the detection output. With such a configuration, the temperature compensation function of the light quantity sensor unit 5 is secured by the control unit 7. The corrected detection output of the light quantity sensor unit 5 is output from the correction unit 72 to the lighting control unit 73.

  The lighting control unit 73 sends a dimming signal to the lighting circuit unit 4 in order to emit light having a reference color temperature or light having a desired color temperature from the light emitting unit 3. When light having a desired color temperature is emitted from the light emitting unit 3, the color temperature is set based on an operation of an operation unit (not shown) by the user. The operation unit sends an operation signal based on this operation to the lighting control unit 73. In response to the operation signal, the lighting control unit 73 refers to the color temperature table stored in the storage unit 6 and generates a dimming signal. In addition, the operation | movement in case the light of the reference | standard color temperature in the lighting control part 73 is radiate | emitted from the light emission part 3 is mentioned later.

  Information indicating the light emission amounts of the red LED 2r, the green LED 2g, and the blue LED 2b necessary for emitting light having a desired color temperature is superimposed on the dimming signal. However, the color temperature of the emitted light from the light emitting unit 3 may be different from a desired color temperature due to a change in the amount of light emission due to the temperature characteristics of the LED 2 or a variation in accuracy of each LED 2. As a countermeasure, the lighting control unit 73 performs feedback control of the light emission amount of the LED 2 based on the detection output of the light amount sensor unit 5. As described above, this detection output is transmitted to the lighting control unit 73 via the temperature estimation unit 71 and the correction unit 72, and the temperature estimation unit 71 and the correction unit 72 change the temperature characteristics of the LED 2 and the light amount sensor unit 5. It is corrected accordingly. Based on the corrected detection output, the light emission amounts of the red LED 2r, the green LED 2g, and the blue LED 2b are adjusted respectively. In this way, the feedback control function of the LED 2 is secured by the control unit 7.

  FIG. 3 shows the waveform of the dimming signal at point A in FIG. This dimming signal is, for example, a current signal composed of a pulse train. The lighting control unit 73 controls the light emission amount of the LED 2 by controlling the duty ratio of this signal, that is, by PWM control. The dimming signal is generated corresponding to each of the red LED 2r, the green LED 2g, and the blue LED 2b. These dimming signals have respective widths. For example, the pulse width of the dimming signal for the red LED 2r is Wr. Similarly, the pulse widths of the dimming signals for the green LED 2g and the blue LED 2b are Wg and Wb, respectively. By adjusting the duty ratio of the dimming signal, these pulse widths Wr, Wg, Wb change. Accordingly, the light emission times of the red LED 2r, the green LED 2g, and the blue LED 2b are adjusted. As a result, the light amounts of the red LED 2r, the green LED 2g, and the blue LED 2b are increased or decreased. The light emission amount control of these LEDs 2 may be performed based on the current value of the dimming signal, that is, the peak value.

  4A and 4B show the relationship between the duty ratio of the dimming signal and the color temperature of the light emitted from the light emitting unit 3, that is, the combined light. The relationship shown in FIG. 5A is the same as the dimming signal for the green LED 2g and the dimming signal for the blue LED 2b. In these dimming signals, the duty ratio increases as the color temperature of the combined light increases. For example, the duty ratio increases in proportion to the increase in color temperature. The relationship illustrated in FIG. 5B is the one that the dimming signal for the red LED 2r has. In this dimming signal, the duty ratio decreases as the color temperature of the combined light increases. For example, the duty ratio decreases in proportion to the increase in color temperature.

  The storage unit 6 stores the above relationship between the color temperature of the combined light and the duty ratio of the dimming signal as a table. In this table, the duty ratio of the dimming signal for each of the red LED 2r, the green LED 2g, and the blue LED 2b is set corresponding to the color temperature of the combined light. Since the change in the duty ratio of the dimming signal leads to an increase or decrease in the light emission amount of the LED 2, this table corresponds to the above color temperature table showing the correspondence between the color temperature of the combined light and the light emission amount of the LED 2.

  5 and 6 show the color temperature adjustment operation of the emitted light and the temporal change of the color temperature in the lighting device 1. In the color temperature adjustment operation, the lighting device 1 is first turned on (S1). Next, the lighting control unit 73 refers to the color temperature table in the storage unit 6 and reads information on the reference light emission amount of the LED 2 corresponding to the reference color temperature. Here, the reference color temperature is a theoretical value Tt. Further, the lighting control unit 73 sends a dimming signal to the lighting circuit unit 4 in order to perform dimming control of each of the LEDs 2, that is, the red LED 2r, the green LED 2g, and the blue LED 2b, so that light is emitted with the read reference light emission amount ( S2). Simultaneously with the light control signal transmission by the lighting control unit 73, a timer (not shown) in the control unit 7 starts time counting (S3). The time count start time is when time t = 0 in FIG. The lighting circuit unit 4 causes the LED 2 to emit light based on the dimming signal from the lighting control unit 73 (S4).

  When a predetermined time elapses after the dimming signal is sent to the LED 2 (S5), the light emission amount gradually increases due to temperature saturation of the LED 2, and then becomes constant. As described above, when the operation of the LED 2 is stabilized, the color temperature of the light emitted from the light emitting unit 3 becomes constant. This time when the color temperature becomes constant is when time t = t1 in FIG. Here, the time t1 is referred to as a standby time. This standby time t1 is set in advance. The timer ends the time count when the standby time t1 has elapsed from the start of the time count.

  The light quantity sensor unit 5 measures the light emission amount of the LED 2 that becomes constant after the standby time t1 is counted by the timer, that is, after the operation of the LED 2 is stabilized (S6). After the measurement, the light amount sensor unit 5 sends the light amount information of the LED 2 to the temperature estimation unit 71. The temperature estimation unit 71 calculates the color temperature of the emitted light from the light emitting unit 3 based on the light quantity information. The calculated color temperature is an actual detection output, that is, a measurement value of the light quantity sensor unit 5. Here, the measured value of the color temperature is Tm.

  After measuring the color temperature, the temperature estimation unit 71 compares the measured value Tm of the color temperature with the theoretical value Tt, and calculates the change in the color temperature, that is, the difference between the measured value Tm and the theoretical value Tt (S7). Here, the difference is Td.

  The temperature estimation unit 71 refers to the first table 61 of the storage unit 6 (S8), reads the ambient temperature corresponding to the calculated difference Td, and estimates the ambient temperature to the actual ambient temperature (S9). This estimated ambient temperature information is sent from the temperature estimation unit 71 to the correction unit 72. The correction unit 72 refers to the second table 62 of the storage unit 6 (S10), and reads and acquires a correction value corresponding to the estimated ambient temperature based on the estimated ambient temperature information from the temperature estimation unit 71 (S10). S11).

  After obtaining the correction value, the lighting control unit 73 corrects the detection output of the light amount sensor unit 5 using the correction value so that the light of the color temperature desired by the user is emitted from the light emitting unit 3. Based on the corrected detection output, feedback control of the light emission amount of the LED 2 is started (S12). The start time of the feedback control is when time t = t2 in FIG. In this feedback control, the lighting control unit 73 adjusts the light emission amount of each color LED 2 so that the color temperature of the emitted light from the light emitting unit 3 becomes a desired value set by the user, that is, the set value Ts. By this adjustment, for example, when the time t = t3 has elapsed as illustrated in FIG. 6, the color temperature of the emitted light from the light emitting unit 3 becomes the set value Ts.

  As described above, the temperature estimation unit 71 measures the change amount of the detection output of the light amount sensor unit 5 and estimates the ambient temperature with reference to the first table 61 based on the change amount. Temperature sensor is not required. For this reason, cost can be reduced. In addition, the storage unit 6 stores a second table 62 that indicates the relationship between the ambient temperature and a correction value that is substantially equal to the change in the detection output due to the temperature characteristics of the light quantity sensor unit 5, and the correction unit 72 is estimated. The correction value corresponding to the ambient temperature is acquired with reference to the second table 62, and the detection output is corrected using the acquired correction value, so that the detection output change due to the temperature characteristic of the light quantity sensor unit 5 is compensated. Can do. In addition, in order to obtain light having a desired color temperature, the lighting control unit 73 feedback-controls the light emission amount of the LED 2 based on the detection output corrected by the correction unit 72. Therefore, it is possible to compensate for the light emission amount change due to the temperature characteristics of the LED 2. For this reason, the color temperature of the emitted light of the illuminating device 1 can be controlled with high accuracy regardless of the change in the ambient temperature.

  Further, the temperature estimating unit 71 calculates the detection output of the light quantity sensor unit 5 after the operation of the LED 2 is stabilized, that is, the amount of change between the measured value Tm and the theoretical value Tt. Therefore, the actual amount of change is accurately calculated. be able to. Therefore, the ambient temperature can be estimated with high accuracy by the temperature estimating unit 71 based on the change. Therefore, the detection output can be corrected according to the ambient temperature estimated with high accuracy. As a result, it is possible to perform highly accurate feedback control on the light emission amount of the LED 2 using the corrected detection output. Furthermore, in the correction of the detection output, the feedback operation for correcting the detection output is unnecessary, and it is only necessary to read out the correction value and correct the detection output according to the correction value, so that quick correction is possible. Become.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made according to the purpose of use. For example, the detection output of the light quantity sensor unit 5 is not limited to the color temperature, and may be chromaticity. The light amount sensor unit 5 is not limited to the above-described configuration, and may include a prism and a plurality of light amount sensors that measure the respective amounts of red light, blue light, and green light that are split by the prism. I do not care. Further, the storage unit 6 may be configured by a memory provided in the microcomputer of the control unit 7. The timer may be provided in the light quantity sensor unit 5. Further, the color temperature of the emitted light from the light emitting unit 3 may be set to a predetermined value by default instead of being set to a desired value by the user. The lighting control unit 73 may perform feedback control based on the light amount of each color light of the LED 2 instead of the color temperature of the emitted light of the light emitting unit 3, that is, the combined light of the LED 2.

The electrical block diagram of the illuminating device which concerns on one Embodiment of this invention. The figure which shows the table memorize | stored in the memory | storage part of the said apparatus. The figure which shows the light control signal waveform in the said apparatus. (A) is a figure which shows the relationship between the duty ratio of the light control signal with respect to the green LED and blue LED of the said apparatus, and the color temperature of the emitted light of the apparatus, (b) is the duty of the light control signal with respect to the red LED of the apparatus. The figure which shows the relationship between ratio and the color temperature of the emitted light. 6 is a flowchart showing a color temperature adjustment operation of emitted light in the apparatus. The figure which shows the time change of the color temperature of the said emitted light.

Explanation of symbols

1 Lighting device 2 LED (light emitting diode)
2b Blue light emitting diode 2g Green light emitting diode 2r Red light emitting diode 3 Light emitting unit 4 Lighting circuit unit 5 Light amount sensor units 52b, 52g, 52r Light amount sensor 6 Storage unit 61 First table (first table)
62 Second table (second table)
7 Control Unit 71 Temperature Estimation Unit 72 Correction Unit 73 Lighting Control Unit 8 Power Supply Unit

Claims (3)

An illumination device comprising: a light emitting diode; a light amount sensor that detects light from the light emitting diode and measures the amount of light; and a control unit that feedback controls the light emission amount of the light emitting diode based on a detection output of the light amount sensor. In the device
The detection output of the light amount sensor when the light emitting diode is controlled to emit light with a reference light emission amount is a change amount that changes from the reference value according to the ambient temperature, with the detection output at a predetermined ambient temperature as a reference value. A storage unit for storing a first table showing a relationship between the ambient temperature and a second table showing a relationship between the ambient temperature and a correction value for correcting the changed detection output,
The correction value is a value that is substantially equal to the change in the detection output due to the temperature characteristics of the light quantity sensor,
The control unit calculates a change amount between a detection output of the light amount sensor and the reference value when the light emitting diode is controlled to emit light with a reference light emission amount, and based on the calculated change amount. The ambient temperature is estimated with reference to the first table, the correction value corresponding to the estimated ambient temperature is acquired with reference to the second table, and a desired amount of light is obtained. Therefore, the illumination apparatus is characterized in that feedback control of the light emission amount of the light emitting diode is performed based on the corrected detection output while correcting the detection output using the acquired correction value.   The lighting device according to claim 1, wherein the control unit calculates a change between the detection output of the light amount sensor and the reference value after the operation of the light emitting diode is stabilized.   The lighting device according to claim 1, wherein the light emitting diode includes a red light emitting diode, a green light emitting diode, and a blue light emitting diode.

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