JP5645242B2 - Illumination device and dimming method of illumination device - Google Patents

Description

  The present invention relates to an illuminating device that combines light of different colors to obtain light of a desired chromaticity, and a dimming method thereof.

  Conventionally, a light emitting diode (LED) is used as a light source in an illumination device such as a backlight device for a liquid crystal display. This lighting device generally includes a plurality of LEDs that emit red (R), green (G), blue (B), amber (A), and the like, and emits these LEDs to emit light of each color. Are combined and the light output of each LED is adjusted to realize combined light of an arbitrary chromaticity. The illuminating device includes a light detection element that can measure the light emitted from the LEDs of each color together, and feeds back the light emission amount measured by the light detection element to the light output of each LED, so that the chromaticity of the combined light is obtained. Adjust.

  As an example of the feedback control method described above, there is a method of feeding back the measurement value obtained by the light detection element to the magnitude of the current flowing through the LED of each color. However, in this method, since it is necessary to adjust the LED current with high accuracy, the LED current control circuit becomes complicated, and it is difficult to reduce the cost of the lighting device.

  On the other hand, the LED current is a predetermined current, and the pulse width modulation (PWM) that periodically controls the light emission / non-light emission of each LED and adjusts the ratio of light emission time (on-duty ratio) of each LED in one cycle. ) To control the light output (see, for example, Patent Document 1).

  In Patent Document 1, the start timing of the light emission time of some LEDs is shifted while maintaining the on-duty ratio of each LED, and the light emission of the LEDs at each time point where the light emission times of each LED overlap each other and each time point where they do not overlap each other. The amount of light emitted from each LED is calculated from the difference between the measured values of the amount of light emitted at each time point.

JP 2008-210853 A

  However, in Patent Document 1, if the on-duty ratio of each color changes, the timings at which the light emission times of the LEDs overlap each other and the times at which each LED does not overlap also change. In addition, if the on-duty ratio of each color changes, there may be a case where the method of shifting the start timing of the light emission time must be changed. Therefore, when calculating the light emission amount of each LED from the difference in the measurement value of the light emission amount at each time point, it becomes difficult to determine at which time point the difference in the measurement value of the light emission amount should be taken. .

  The present invention has been made in view of the above problems, and its purpose is to measure the light emission amount at any measurement timing when calculating the light emission amount of each light-emitting element from the difference between the light emission amount measurement values. It is to provide an illuminating device and a dimming method thereof that can easily determine whether or not to take the difference.

A first feature of the present invention is an illumination device that combines light of different colors to obtain light of a desired chromaticity. This lighting device has a plurality of light emitting elements that emit light of different colors and a light emission time in one cycle for each of the light emitting elements so that the chromaticity of the combined light by the plurality of light emitting elements becomes a desired chromaticity. A light emission time control unit for controlling, an on / off control unit for periodically controlling light emission and non-light emission of each light emitting element while maintaining the light emission time controlled by the light emission time control unit, and a plurality of light emitting elements A light receiving element that measures the light emission amount of emitted light together, a light emission amount calculating unit that calculates the light emission amount of any one of the plurality of light emitting elements from the light emission amount measured by the light receiving element, and a desired color And a color mixture ratio storage unit for storing color mixture ratio data of each color for obtaining the degree. The on / off control unit forms all the light emitting states in which all the light emitting elements emit light within one cycle common to each light emitting element, and then changes one light emitting element from the light emitting state to the non-light emitting state. Control exclusively. The light emission amount calculation unit calculates the light emission amount of one light emitting element by subtracting the light emission amount in the non-light emission state of one light emitting element from the light emission amount in all light emission states measured by the light receiving element. The light emission time control unit controls the light emission time of one light emitting element based on the light emission amount of one light emitting element and the color mixing ratio data stored in the color mixing ratio storage unit.

  According to the first feature of the present invention, any one of the plurality of light emitting elements is exclusively shifted from the light emitting state to the non-light emitting state, and the difference in light emission amount measured by the light receiving element before and after the transition. Is the light emission amount of the one light emitting element. Thereby, in order to calculate the light emission amount of each light emitting element, it is possible to easily determine at which measurement timing the difference between the measurement values of the light emission amount should be taken. Further, the change in the on-duty ratio does not depend on the determination of the measurement timing. Further, it is not necessary to shift the light emission start timing. Therefore, the control circuit for taking the measurement timing described above is simplified, and a control circuit for shifting the light emission start timing becomes unnecessary.

The second feature of the present invention is a dimming method for an illumination apparatus that combines light of different colors to obtain light of desired chromaticity. In this dimming method, the first step of measuring the amount of light emitted from a plurality of light emitting elements that respectively emit light of different colors, and the amount of light emitted from any one of the plurality of light emitting elements from the measured amount of light emitted. The light emission time in one cycle of one light emitting element is calculated based on the second stage to be calculated, the color mixture ratio of each color to obtain a desired chromaticity by combining light of different colors and the calculated light emission amount. And a fourth stage for periodically controlling light emission and non-light emission of each light emitting element while maintaining the calculated light emission time. In a fourth stage, all the light emitting elements emit light in a common period with each of the light emitting elements, and then one light emitting element is changed from the light emitting state to the non-light emitting state. Control exclusively. In the second step, the light emission amount of the one light emitting element is calculated by subtracting the light emission amount of the one light emitting element in the non-light emitting state from the light emission amount in the total light emitting state measured by the light receiving element. In the third stage, the light emission time of one light emitting element is calculated based on the light emission amount and color mixture ratio of one light emitting element.

  According to the illumination device and the dimming method of the present invention, when calculating the light emission amount of each light emitting element from the difference in the measurement value of the light emission amount, at which measurement timing should the difference in the measurement value of the light emission amount be taken? Can be easily determined.

It is a block diagram which shows the structure of the illuminating device concerning embodiment of this invention. FIG. 2A is a time chart showing a control method of light emission / non-light emission of each LED1 to LED4 according to the first embodiment, and FIG. 2B is a time chart showing each LED1 to LED4 according to the second embodiment. It is a time chart which shows the control method of light emission / non-light emission. FIG. 3A is a time chart showing the same control method as in FIG. 2A, and FIG. 3B is a graph showing an example of the light emission amount of each LED1 to LED4. It is a flowchart which shows the outline of the light control method of the illuminating device of FIG. FIG. 5A is a flowchart showing an example of a detailed processing procedure in step S03 of FIG. 4, and FIG. 5B is a flowchart showing an example of a detailed processing procedure in step S05 of FIG. It is a table | surface which shows an example of the mixing ratio of each RGB in the case of mixing colors by RGB 3 colors.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same parts are denoted by the same reference numerals.

  With reference to FIG. 1, the structure of the illuminating device concerning embodiment of this invention is demonstrated. The illumination device according to the embodiment of the present invention includes red (R), green (G), blue (B), and blue as an example of a plurality of light-emitting elements that emit light of different colors. A first light emitting diode (hereinafter referred to as “LED”) 11a, a second LED 11b, a third LED 11c, and a fourth LED 11d each emitting a color (A: Amber) are provided. The illuminating device emits the first to fourth LEDs 11a to 11d to synthesize light of each color, and adjusts the light output of the first to fourth LEDs 11a to 11d, thereby generating synthesized light of desired chromaticity. Realize.

  The lighting device includes a light emitting unit 11 including first to fourth LEDs 11a to 11d, a light emitting time control unit 12 that controls a light emitting time in one cycle, and a light emitting time for each of the first to fourth LEDs 11a to 11d. An LED management unit 13 (on / off control unit) that periodically controls light emission and non-light emission of each of the first to fourth LEDs 11a to 11d while maintaining the light emission time controlled by the control unit 12, and light emission A light receiving element 14 that measures the light emission amount of the light emitted from the unit 11 together, and a light emission amount calculating unit 21 that calculates the light emission amount of each of the first to fourth LEDs 11 from the light emission amount measured by the light receiving element 14; Each of the first to fourth LEDs 11a to 11d is driven under the control of the color mixture ratio storage unit 15 for storing the color mixture ratio data of each RGBA color to obtain a desired chromaticity and the LED management unit 13. And an ED drive circuit 24.

  The light emitted from each of the first to fourth LEDs 11 a to 11 d is received by one light receiving element 14. Therefore, the light emission amount measured by the light receiving element 14 at the timing when each of the first to fourth LEDs 11a to 11d emits light alone is the light emission amount of each of the first to fourth LEDs 11a to 11d, and the first The light emission amount measured by the light receiving element 14 at the timing when any two or more of the fourth LEDs 11a to 11d emit light is the light emission amount of the combined light obtained by combining the light emitted by the two or more LEDs.

  The light emission amount calculation unit 21 temporarily converts the analog signal output as the light emission amount from the light receiving element 14 into a digital signal (data), and temporarily stores the converted light emission amount data. Using the light emission amount data stored in the buffer 34 and the light emission amount temporary holding buffer 34, the non-light emission state of the one LED from the light emission amount measured in the light emission state of any one of the LEDs 11a to 11d. , A light emission amount comparison unit 35 for subtracting the light emission amount measured in, a light emission amount holding buffer (R) 32a for temporarily storing a difference in light emission amount calculated by the light emission amount comparison unit 35, and a light emission amount holding buffer (G ) 32b, a light emission amount holding buffer (B) 32c and a light emission amount holding buffer (A) 32d, and a first timer 33 for counting a predetermined time.

  The AD converter 31 and the light emission amount temporary holding buffer 34 repeatedly perform AD conversion of an analog signal received from the light receiving element 14 and storage of data at a constant time interval counted by the first timer 33. The light emission amount temporary holding buffer 34 can simultaneously store data of a plurality of light emission amounts.

  In the case where each of the first to fourth LEDs 11a to 11d transitions independently from the light emitting state to the non-light emitting state, the light emitting amount comparison unit 35 stores the light emitting amount temporarily holding buffer 34 before and after the transition. The difference between the stored light emission amounts is calculated. The LED management unit 13 causes each of the first to fourth LEDs 11a to 11d to transition independently from the light emitting state to the non-light emitting state.

  The light emission amount holding buffers 32a to 32d hold the light emission amount differences calculated by the light emission amount comparison unit 35 as the light emission amounts of the first to fourth LEDs 11a to 11d, respectively.

  The color mixture ratio storage unit 15 stores data of the color mixture ratios of the respective RGBA colors so that the chromaticity of the combined light by the first to fourth LEDs 11a to 11d becomes a desired chromaticity. By adjusting the ratio of the light output of each of the LEDs 11a to 11d based on the color mixture ratio of each RGBA color, the chromaticity of the combined light from the first to fourth LEDs 11a to 11d can be adjusted to a desired chromaticity. . In the case of mixed colors of three RGB colors, for example, as shown in FIG. 6, the mixing ratios of RGB are grouped for each color type (1, 2, 3,...) Of the synthesized light.

  The light emission time control unit 12 has the color mixture ratio data and light emission amount calculation unit 21 stored in the color mixture ratio storage unit 15 so that the chromaticity of the combined light from the first to fourth LEDs 11a to 11d becomes a desired chromaticity. The light emission time calculation unit 41 that calculates the light emission time of the first to fourth LEDs 11a to 11d based on the light emission amount calculated by the above, and the calculated light emission time of the first to fourth LEDs 11a to 11d are held. A light emission time holding unit 22 and a light emission time management unit 23 for managing the light emission times of the first to fourth LEDs 11a to 11d based on the held light emission time are provided.

  The light emission time calculation unit 41 emits light amount holding buffer 32a so that the ratio of the light output of the first to fourth LEDs 11a to 11d becomes the color mixture ratio of desired chromaticity stored in the color mixture ratio storage unit 15. Based on the light emission amounts stored in .about.32d, the light emission times of the first to fourth LEDs 11a-11d are calculated. The light output increases as the light emission amount or the light emission time increases, so the light emission time is increased when the stored light emission amount is small, and the light emission time is shortened when the stored light emission amount is large. Thus, the ratio of the light output of the first to fourth LEDs 11a to 11d can be adjusted.

  Note that the light emission time calculation unit 41 repeatedly calculates the light emission time at regular time intervals counted by the second timer 25. The fixed time interval counted by the second timer 25 is longer than the fixed time interval counted by the first timer 33.

  The light emission time holding unit 22 includes a light emission time holding buffer (R) 42a for holding the light emission time of the first LED 11a, a light emission time holding buffer (G) 42b for holding the light emission time of the second LED 11b, and a third A light emission time holding buffer (B) 42c for holding the light emission time of the LED 11c and a light emission time holding buffer (A) 42d for holding the light emission time of the fourth LED 11d are provided. The LED management unit 13 selects any one of the light emission time holding buffers 42 a to 42 d and writes the light emission time data calculated by the light emission time calculation unit 41.

  The light emission time management unit 23 is input to the reference value input unit 45 that receives the light emission time held by the light emission time holding buffers 42 a to 42 d as a reference value, the counter 46 that counts time, and the reference value input unit 45. A comparator 47 that compares the light emission time with the time counted by the counter 46 is provided. When the time counted by the counter 46 reaches the light emission time input to the reference value input unit 45, the light emission time management unit 23 determines the time counted by the counter 46 for the LED management unit 13 and the LED drive circuit 24. Output.

  The LED drive circuit 24 drives each of the first to fourth LEDs 11 a to 11 d under the control of the LED management unit 13 based on the time output from the light emission time management unit 23.

  The LED management unit 13 sets the current flowing through the LEDs 11a to 11d as a predetermined current, periodically controls the light emission / non-light emission of the LEDs 11a to 11d, and the ratio of the light emission time of each LED 11a to 11d in one cycle (on duty) The light output of each of the LEDs 11a to 11d is adjusted by pulse width modulation (PWM) for adjusting the ratio.

  Further, the LED management unit 13 may control the order in which the LEDs 11a to 11d emit light. You may fix the order of LED to light-emit in order of R-> G-> B-> A, for example. This facilitates control. Alternatively, the light emission order may be changed for each cycle, such as R → G → B → A, G → R → B → A,. Thereby, a composite color can be averaged. Alternatively, the light emission order may be random. Thereby, a composite color can be averaged.

  In this way, the illumination device shown in FIG. 1 feeds the combined light of desired chromaticity by feeding back the light emission amount of each LED 11a to 11d measured by the light receiving element 14 to the on-duty ratio of each LED 11a to 11d. obtain.

  Next, with reference to FIG. 4, the outline of the light control method of the illuminating device of FIG. 1 is demonstrated.

  (A) First, in step S03, the light receiving element 14 repeatedly measures the light emission amounts of the first to fourth LEDs 11a to 11d, and stores the plurality of AD converted light emission amount data in the light emission amount temporary storage buffer 34. (First stage). Then, the light emission amount comparison unit 35 calculates the light emission amount of the one LED by subtracting the light emission amount measured in the non-light emission state of one LED from the light emission amount measured in the light emission state of one LED ( Second stage). And the difference of the light emission amount calculated by the light emission amount comparison part 35 is memorize | stored in the light emission amount holding buffers 32a-32d as the light emission amount of the said one LED. By sequentially applying the first to fourth LEDs 11a to 11d as the "one LED" described above, the light emission amount of each of the first to fourth LEDs 11a to 11d is measured, and the light emission amount data is emitted. The data can be stored in the amount holding buffers 32a to 32d, respectively.

  (B) Proceeding to step S05, the light emission time calculation unit 41 performs the first based on the light emission amount data stored in the light emission amount holding buffers 32a to 32d and the color mixture ratio data stored in the color mixture ratio storage unit 15. The light emission time in one cycle of each of the fourth to fourth LEDs 11a to 11d is calculated (third stage).

  (C) Proceeding to step S07, the light emission time management unit 23 updates the previous light emission time to the light emission time calculated in step S05, and proceeding to step S09, the LED management unit 13 maintains the updated light emission time. Meanwhile, the light emission / non-light emission of each of the LEDs 11a to 11d is periodically controlled (fourth stage). At this time, the LED management unit 13 changes each of the first to fourth LEDs 11a to 11d independently from the light emitting state to the non-light emitting state. That is, control is performed so that the two or more LEDs 11a to 11d do not simultaneously transition from the light emitting state to the non-light emitting state. After step S09, the process returns to step S03 again. Thereby, in S03 stage, the difference of the emitted light amount before and behind the said transition is computable as each emitted light amount of LED11a-11d.

  Next, an example of a detailed processing procedure in step S03 of FIG. 4 will be described with reference to FIG.

  (Ii) First, in step S31, the process waits for the first timer 33 to count a predetermined time. When the first timer 33 counts the predetermined time (YES in S31), the process proceeds to step S33, and the light emission amount calculation unit 21 stores the light emission amount data converted by the AD converter 31 in the light emission amount temporary holding buffer 34. Write.

  (B) Proceeding to step S35, the LED management unit 13 determines whether or not the color of the light emitting LED changes. If the color of the light emitting LED has not changed (NO in step S35), there is no change in the light emitting state / non-light emitting state of each LED 11a to 11d, so the process returns to step S31, and steps S31 and S33. To implement. On the other hand, if the color of the light emitting LED has changed (YES in step S35), the LED 11a to 11d has changed to the light emitting / non-light emitting state, and the process proceeds to step S37. Specifically, the LED management unit 13 transmits a trigger signal for light emission amount calculation to the light emission amount calculation unit 21 when the light emission state / non-light emission state of each LED 11a to 11d is changed. The trigger signal includes identification information of the LED in which the change of the light emission state / non-light emission state has occurred.

  In step S <b> 37, the light emission amount comparison unit 35 that has received the trigger signal calculates the average value of the n light emission amount data stored in the light emission amount temporary storage buffer 34 and the latest value converted by the AD converter 31. Take the difference from the emission data. And the said difference is memorize | stored in the corresponding light emission amount holding | maintenance buffer 32a-32d as the light emission amount of LED in which the change occurred in the light emission state / non-light emission state. At this time, since only one LED has changed between the light emitting state / non-light emitting state, the corresponding light emission amount holding buffers 32a to 32d can be specified as one.

  (Ii) Thereafter, the process proceeds to step S39, and the light emission amount data stored in the light emission amount temporary storage buffer 34 is erased. Thereafter, the process returns to step S31 again, and the first timer 33 starts counting a predetermined time.

  In this way, the LED management unit 13 monitors whether or not there is a change in the light emission state / non-light emission state of each of the LEDs 11a to 11d, and only when there is such a change, the light emission amount calculation unit 21 Send trigger signal. Thus, the light emission amount calculation unit 21 that has received the trigger signal stores the light emission amount stored in the light emission amount temporary holding buffer 34 before receiving the trigger signal and the light emission amount temporary holding buffer 34 after receiving the trigger signal. The difference from the emitted light amount can be calculated as the light emission amount of the LED whose light emission state / non-light emission state has changed. Therefore, in order to calculate the light emission amounts of the respective LEDs 11a to 11d, it is possible to easily determine at which measurement timing the difference between the measurement values of the light emission amounts should be taken.

  Next, an example of a detailed processing procedure in step S05 in FIG. 4 will be described with reference to FIG. First, in step S51, the process waits for the second timer 25 to count a predetermined time. When the second timer 25 counts the predetermined time (YES in S51), the process proceeds to step S53, and the light emission time calculation unit 41 reads the light emission amount data stored in each of the light emission amount holding buffers 32a to 32d. Then, the process proceeds to step S55, and the light emission time calculation unit 41 sets each of the LEDs 11a to 11d based on the read light emission amount data so that the light output ratio of each of the LEDs 11a to 11d becomes a color mixture ratio of desired chromaticity. Is calculated. The calculated light emission times are respectively stored in the light emission time holding buffers 42a to 42d. Thereafter, the process returns to step S51 again, and the second timer 25 starts counting a predetermined time.

In this way, the light emission time calculation unit 41 can repeatedly calculate the light emission time at regular time intervals counted by the second timer 25.
(First embodiment)

  Next, with reference to FIG.2 and FIG.3, the Example of the control method of light emission / non-light emission of each LED11a-11d in S09 step of FIG. 4 is described. By applying the control method described here, each of the LEDs 11a to 11d can be exclusively controlled from the light emitting state to the non-light emitting state. 2 and 3, the four LEDs 11a to 11d are arbitrarily replaced with LED1, LED2, LED3, and LED4.

  With reference to FIGS. 2 (a), 3 (a), and 3 (b), a control method of light emission / non-light emission of each LED1 to LED4 according to the first embodiment will be described. A portion with a dotted pattern indicates the light emission time of each LED1 to LED4, and a white portion without a pattern indicates the non-light emission time of each LED1 to LED4.

  As shown to Fig.2 (a), the LED management part 13 sets the period (T1, T2) of LED1-LED4, and its phase equally. Simultaneously with the start of one cycle (T1, T2), LED1 starts to emit light, but LEDs 2 to 4 maintain a non-light emitting state. And in order of LED2, LED3, and LED4, it changes from a non-light-emission state to a light emission state, and all the light emission states which all LED1-LED4 light-emitted are formed. Thereafter, at the timing TM2, the LED 2 transitions from the light emitting state to the non-light emitting state by removing other LEDs (LEDs 1, 3, 4) independently. Further, thereafter, at timings TM3, TM4, and TM1, LED3, LED4, and LED1 sequentially transition exclusively from the light emitting state to the non-light emitting state.

  Accordingly, as shown in FIGS. 3A and 3B, if the light emission amount measured immediately after the timing TM2 is subtracted from the light emission amount measured immediately before the timing TM2, the difference PD2 of the light emission amount is obtained. It can obtain | require as light emission amount of LED2. Similarly, if the light emission amount measured immediately after each timing TM3, TM4 and TM1 is subtracted from the light emission amount measured immediately before each timing TM3, TM4 and TM1, the difference PD3, PD4 and PD1 of the light emission amount is obtained. It can obtain | require as each light-emission amount of LED3, LED4, and LED1.

  In this manner, the light emission amount comparison unit 35 determines the difference between the light emission amounts stored in the light emission amount temporary holding buffer 34 before and after each timing TM1 to TM4 in step S37 of FIG. It can be calculated as the amount of luminescence.

  In addition, about LED1 of Fig.2 (a), the light emission amount in the non-light-emission state which is not light-emitting any LED will be subtracted from the light emission amount in a single light emission state. Thereby, the background (noise) can be removed from the light emission amount in the single light emission state, and the measurement accuracy of the light emission amount is improved.

As described above, any one of the plurality of LEDs 1 to 4 is exclusively shifted from the light emitting state to the non-light emitting state, and the difference in the light emission amount measured by the light receiving element 14 before and after the transition is determined as the one LED. The amount of light emitted from the LED. Thereby, in order to calculate the light emission amount of each LED1 to 4, it is possible to easily determine at which measurement timing the difference between the measurement values of the light emission amount should be taken. Further, the change in the on-duty ratio does not depend on the determination of the measurement timing. Further, it is not necessary to shift the light emission start timing. Therefore, a control circuit for taking the measurement timing is simplified, and a control circuit for shifting the light emission start timing becomes unnecessary.
(Second embodiment)

  With reference to FIG.2 (b), the control method of light emission / non-light emission of each LED1-LED4 concerning a 2nd Example is demonstrated. A portion with a dotted pattern indicates the light emission time of each LED1 to LED4, and a white portion without a pattern indicates the non-light emission time of each LED1 to LED4.

  The LED management unit 13 sets the periods (T1, T2) and phases of the LEDs 1 to 4 to be equal to each other. Simultaneously with the start of one cycle (T1, T2), all LEDs 1 to 4 start to emit light. Thereby, all the light emission states (Ga) in which all the LEDs 1 to 4 emit light are formed. Thereafter, the LED1, LED2, LED3, and LED4 are shifted in an exclusive order from the light emitting state to the non-light emitting state.

  At the same time as the LED 2 is changed from the light emitting state to the non-light emitting state, the LED 1 that has been in the non-light emitting state is changed to the light emitting state. Similarly, the LED 3 is changed from the light emitting state to the non-light emitting state, and at the same time, the LED 2 that has been in the non-light emitting state is changed to the light emitting state, and the LED 4 is changed from the light emitting state to the non-light emitting state. The LED 3 that has been in the non-light emitting state is shifted to the light emitting state.

  Thereby, only the LED 1 is in the non-light emitting state, and the single non-light emitting state G1 in which the other LEDs (LEDs 2 to 4) are in the light emitting state is formed after the total light emitting state Ga. Similarly, only LED 2 is in a non-light emitting state, and other LED (LED 1, 3, 4) is in a light emitting state, LED 2 single non-light emitting state G2 is formed, only LED 3 is in a non-light emitting state, The LED 3 alone in the non-light emitting state G3 in which the LEDs (LEDs 1, 2, 4) in the light emitting state are formed is formed, and only the LED 4 is in the non light emitting state, and the other LEDs (LEDs 1 to 3) are in the light emitting state. A single non-light emitting state G4 is formed.

  After the LED 4 independent non-light emitting state G4, the LED 4 starts to emit light again, and the light emitting states of the LEDs 1 to 4 are continued according to the on-duty ratios of the LEDs 1 to 4 managed by the light emission time management unit 32.

  In FIG.2 (b), the time for which each state (Ga, G1-G4) continues is preset. Specifically, if the time is set to be sufficiently longer than the predetermined time counted by the first timer 33, a plurality of light emission amount data in each state (Ga, G1 to G4) is stored in the light emission amount temporary holding buffer 34. Therefore, the measurement accuracy of the received light amount is improved by taking the average value of the plurality of light emission amount data.

  The light emission amount calculating unit 21 measures the light emission amount measured by the light receiving element 14 in the total light emission state Ga, using the light receiving element 14 in the single non-light emission state (G1 to G4) of any one of the LEDs 1 to LED4. By subtracting the emitted light amount, it is possible to calculate the light emission amount of one LED that is in a single non-light emitting state. Similarly, by subtracting the light emission amount measured by the light receiving element 14 in the single non-light emission state (G1 to G4) of each of the LEDs 1 to LED4 from the light emission amount measured by the light receiving element 14 in the total light emission state Ga. The amount of light emitted from each of the LEDs 1 to 4 can be calculated. Moreover, in order to calculate the light emission amount of the one LED by previously determining the order of the LEDs forming the single non-light emission state (G1 to G4), the difference in the measurement value of the light emission amount at which measurement timing is calculated. It can be easily determined whether or not to take.

Compared with the comparative example in which the individual light emitting states of the LEDs 1 to 4 are formed, the amount of fluctuation of the light amount of the entire lighting device is reduced, and the flickering degree is reduced. Moreover, since the ratio of the light emission time of all the LEDs 1 to 4 in one cycle can be increased, the light quantity of the entire lighting device increases.
(Other embodiments)

  As described above, the present invention has been described by way of one embodiment and two examples. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the light emitting unit 11 includes a plurality of LEDs 11a to 11d that emit light of different colors, but the number of LED chips and the number of light emitting portions included in each of the first to fourth LEDs 11a to 11d are single. Or a plurality of them.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a wide range of lighting devices that obtain light of desired chromaticity by combining light of different colors, such as a backlight device for a liquid crystal display and a lighting device that produces a wall surface of a building. .

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters according to the scope of claims reasonable from this disclosure.

11 Light Emitting Unit 11a First LED (First Light Emitting Element)
11b 2nd LED (2nd light emitting element)
11c 3rd LED (3rd light emitting element)
11d 4th LED (4th light emitting element)
12 Light emission time control unit 13 LED management unit (on / off control unit)
DESCRIPTION OF SYMBOLS 14 Light receiving element 15 Color mixing ratio memory | storage part 21 Light emission amount calculation part 22 Light emission time holding part 23 Light emission time management part 24 LED drive circuit 25 2nd timer 31 AD converter 32a-32d Light emission amount holding buffer 33 1st timer 34 Light emission amount Temporary holding buffer 35 Light emission amount comparison unit 41 Light emission time calculation units 42a to 42d Light emission time holding buffer 45 Reference value input unit 46 Counter 47 Comparator

Claims (2)

A lighting device that combines light of different colors to obtain light of desired chromaticity,
A plurality of light emitting elements each emitting light of different colors;
A light emission time control unit that controls the light emission time in one cycle for each of the light emitting elements, so that the chromaticity of the combined light by the plurality of light emitting elements becomes the desired chromaticity;
An on / off controller that periodically controls light emission and non-light emission of each of the light emitting elements while maintaining the light emission time controlled by the light emission time controller;
A light receiving element for measuring together the amount of light emitted by the plurality of light emitting elements;
A light emission amount calculating unit for calculating a light emission amount of any one of the plurality of light emitting elements from a light emission amount measured by the light receiving element;
A color mixture ratio storage unit for storing color mixture ratio data of each color to obtain a desired chromaticity,
The on / off control unit forms a total light emitting state in which all of the light emitting elements emit light within one cycle common to the light emitting elements, and then removes the one light emitting element from the light emitting state. Control exclusively to the non-light-emitting state,
The light emission amount calculation unit calculates the light emission amount of the one light emitting element by subtracting the light emission amount in the non-light emission state of the one light emitting element from the light emission amount in the total light emission state measured by the light receiving element,
The light emission time control unit controls the light emission time of the one light emitting element based on the light emission amount of the one light emitting element and the color mixing ratio data stored in the color mixing ratio storage unit. .   A first step of measuring light emission amounts of a plurality of light emitting elements that respectively emit light of different colors;
  A second stage of calculating a light emission amount of any one of the plurality of light emitting elements from the measured light emission amount;
  A third step of calculating a light emission time in one cycle of the one light emitting element based on a color mixture ratio of each color and a calculated light emission amount for obtaining the desired chromaticity by combining the lights of different colors; ,
  And a fourth step of periodically controlling light emission and non-light emission of each of the light emitting elements while maintaining the calculated light emission time.
  In the fourth step, all light emitting elements emit light in a common period in each of the light emitting elements, and then the one light emitting element is removed from the light emitting state. Control exclusively to the flash state,
  In the second step, the light emission amount of the one light emitting element is calculated by subtracting the light emission amount of the one light emitting element in the non-light emitting state from the light emission amount measured by the light receiving element.
  In the third step, the light emission time of the one light emitting element is calculated based on the light emission amount of the one light emitting element and the color mixture ratio.
  A lighting control method for an illuminating device.

Images