JP4736098B2 - LIGHTING DEVICE AND LIGHTING DEVICE CONTROL METHOD - Google Patents

Description

  The present invention relates to a lighting device for a transmissive display device that employs a light emitting diode as a light emitting element, and a method for controlling the lighting device.

  The light source of the illuminating device for a transmissive display device such as a liquid crystal display is mainly a cold cathode tube, but from the viewpoint of wide color reproduction and environmental consideration (mercury-less), a light emitting diode (LED). Is promising as a light source that can be replaced by a cold-cathode tube. In particular, in liquid crystal displays, when red LEDs, green LEDs, and blue LEDs are used as the light source of an illumination device, the color reproduction range is expanded, so that it has been actively studied.

Since the current LED has a lower emission intensity than a cold cathode tube, in order to obtain a luminance of 200 cd / m ² or more on a 10-inch or higher type liquid crystal display, it is necessary to arrange a plurality of LEDs in the lighting device There is. Further, as shown in FIG. 11, the LED has a characteristic that the emission intensity with respect to the junction temperature is different for each color. In general, since the red LED and the green and blue LEDs have different structures, the reduction in the emission intensity accompanying the increase in the junction temperature is larger for the red LEDs than for the green and blue LEDs. Further, the decrease in emission intensity due to continuous lighting is accelerated as the junction temperature increases as shown in FIG.

  Now consider the junction temperature of the LEDs in the lighting device. Usually, the liquid crystal display is installed in a direction perpendicular to a horizontal plane. At this time, the air heated by the heat generated from the LED has a low specific gravity and rises. As a result, the temperature of the upper base material becomes higher than that of the central portion, and the temperature of the lower base material becomes lower than that of the central portion. At this time, as shown in FIG. 13, the junction temperature of the upper LED is higher than that of the central portion, and the junction temperature of the lower LED is lower than that of the central portion.

  Therefore, when red LED, green LED, and blue LED are used for a illuminating device for a transmissive display device, the luminance and chromaticity change and the luminance unevenness and color of the light emitting surface in continuous lighting compared to the cold cathode tube. It can be seen that unevenness increases. The change or unevenness greatly affects the appearance of the displayed image, and therefore, operations that require uniform image display for a long time with the same brightness and white color (for example, diagnostic applications in the medical field and color finish confirmation applications in the printing field) Etc.) has a problem in replacing the light source of the illumination device for the transmissive display device from the cold cathode tube to the LED.

Therefore, as in Patent Document 1 and Patent Document 2, the light source in the lighting device is divided into a plurality of light source units, the light emission intensity of each light source unit is detected by a color sensor, and the detection values of the color sensors are equal. A technique for adjusting the light emission intensity of each light source unit has been proposed.
JP 2006-119268 A JP-A-2005-208486

  However, in order to accurately detect the light emission intensity with the color sensor, it is necessary to dispose each light source unit and the color sensor at equal distances as in Patent Document 1. Or it is necessary to provide the optical transmission means (for example, optical fiber) of the same characteristic between each light source unit and a color sensor like patent document 2. FIG. For this reason, there is a problem that the structure becomes complicated due to a decrease in the degree of freedom of arrangement of the color sensor and the provision of optical transmission means.

  In view of the above-described problems, an object of the present invention is to provide an illumination device and a method for controlling the illumination device that can adjust the light intensity of a light-emitting element by detecting the emission intensity without complicating the configuration.

  In order to solve the above-described problems, the present invention provides a driving unit that divides a light emitting region into a plurality of divided regions and drives a light emitting element for each of the divided regions, and is provided in common for the plurality of divided regions. A light intensity detection means, a storage means for storing a reference value of emission intensity for each divided area when the light emitting element is driven for each divided area, and driving the light emitting element for each divided area; The light intensity detection means detects the light intensity for each of the divided areas, compares the detected value of the light intensity for each of the divided areas with the reference value of the light intensity for each of the divided areas, based on the comparison result, Control means for performing first control for controlling the light intensity of the light emitting element for each of the divided regions is provided.

  In the illuminating device according to the present invention, the storage means stores a reference value of the light intensity of the entire light emitting area when the light emitting element is driven over the entire light emitting area, and the control means includes the entire division. Driving the light emitting element in the region, detecting the light intensity of the entire light emitting region by the light intensity detecting means, and comparing the detected value of the light intensity of the entire light emitting region with the reference value of the light intensity of the entire light emitting region. The second control for controlling the light intensity of the light emitting element is performed based on the comparison result.

  In the lighting device according to the present invention, the first control is performed at a predetermined cycle.

  The illumination device according to the present invention is characterized in that a divided region composed of a plurality of divided regions and a light intensity detecting means common to the plurality of divided regions is made one unit, and a plurality of units are combined. .

  The lighting device control method according to the present invention divides a light emitting region into a plurality of divided regions, drives a light emitting element for each divided region, and provides light intensity detecting means provided in common to the plurality of divided regions. The light intensity is detected in the storage means, and the storage means storing the reference value of the light intensity for each divided region when the light emitting element is driven for each divided region, the detected value of the light intensity for each divided region and the The light intensity reference value for each divided area stored in the storage means is compared, and the light intensity of the light emitting element is controlled for each divided area based on the comparison result.

  In the lighting device control method according to the present invention, in the above-described lighting device control method, the storage means includes a reference value of the light intensity of the entire light emitting region when the light emitting element is driven in the entire light emitting region. Is stored, the light emitting elements of all the divided regions are driven, the light intensity detecting means detects the light intensity of the entire light emitting region, the detected value of the light intensity of the entire light emitting region and the entire light emitting region of the light emitting region are detected. A light intensity reference value is compared, and the light intensity of the light emitting element is controlled based on the comparison result.

  According to the present invention, the light emitting area is divided into a plurality of divided areas, and the light intensity detecting means is provided in common for the plurality of divided areas. Then, the light intensity is detected by a common light intensity detection means for each divided area, and the detected value of the light intensity of each divided area is compared with the reference value of the light intensity set for each divided area. The light intensity of the light emitting element is controlled based on the comparison result. Thereby, even if it is a case where one light intensity detection means is used, the brightness | luminance and chromaticity of the light emission surface of an illuminating device can be controlled uniformly.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a lighting apparatus to which the present invention is applied. The lighting device to which the present invention is applied can be used as a light source of a transmissive display device such as a liquid crystal display.

  As shown in FIG. 1, in a lighting device to which the present invention is applied, a plurality of light emitting elements are disposed on the upper surface of a base substrate 11. The entire light emitting area is divided into a plurality of divided areas, for example, four divided areas A1 to A4. Here, a plurality of light emitting elements respectively arranged in the divided regions A1 to A4 are shown as light emitting element groups 12-1 to 12-4, respectively. One color sensor 13 is provided in common for the entire light emitting region. Here, although the number of divisions of the divided areas is four, this is an example, and the number of divisions of the divided areas is not limited to four.

  FIG. 2 shows an outline of the configuration of a lighting device to which the present invention is applied. As shown in FIG. 2, the plurality of light emitting element groups 12-1 disposed in the divided area A1 include a red LED group 21R-1, a green LED group 21G-1, and a blue LED group 21B-1. It consists of. The drive circuit 22-1 drives the plurality of light emitting element groups 12-1 disposed in the divided area A1, and as shown in FIG. 3, the red LED group disposed in the divided area A1. LED drive circuit 23R-1 for driving 21R-1, LED drive circuit 23G-1 for driving green LED group 21G-1, and LED drive circuit 23B-1 for driving blue LED group 21B-1 Contains. The LED drive circuits 23R-1, 23G-1, and 23B-1 are based on the drive signal from the control unit 25, the red LED group 21R-1, the green LED group 21G-1, and the blue LED group 21B-1. The emission intensity of each can be controlled.

  Similarly, the plurality of light emitting element groups 12-2 to 12-4 respectively disposed in the divided regions A2 to A4 include a red LED group 21R-2 to 21R-4 and a green LED group 21G-2 to 21G. -4 and the blue LED groups 21B-2 to 21B-4. The red LED groups 21R-2 to 21R-4, the green LED groups 21G-2 to 21G-4, and the blue LED groups 21B-2 to 21B-4 are driven by driving circuits 22-2 to 22-4. The drive circuits 22-2 to 22-4 are arranged based on the drive signal from the control unit 25, and the red LED groups 21R-2 to 21R-4 respectively disposed in the divided regions A2 to A4. The light emission intensities of the green LED groups 21G-2 to 21G-4 and the blue LED groups 21B-2 to 21B-4 can be controlled, respectively. Note that the light emitting elements may be connected to the driving circuit in series or in parallel for each color.

  The color sensor 13 includes red, green, and blue luminance sensors using band-pass filters for red, green, and blue light, and white light from the light emitting element groups 12-1 to 12-4 is red. The brightness of each color can be detected by splitting the light into green, blue and monochromatic light. The detection signal of the color sensor 13 is sent to the control unit 25.

  The storage unit 26 includes reference values Ra1 to Ra4 when only the light emitting element groups 12-1 to 12-4 are turned on for each of the divided areas A1 to A4, and the light emitting element groups 12-1 of all the divided areas. The reference value Rt when all of .about.12-4 are turned on is stored.

  The control unit 25 emits light by the first control using the reference values Ra1 to Ra4 when the light emitting element groups 12-1 to 12-4 are turned on for each of the divided regions A1 to A4 from the storage unit 26. The emission intensity of each of the element groups 12-1 to 12-4 is adjusted. Further, by using the reference value Rt when the light emitting element groups 12-1 to 12-4 in all the divided regions are turned on, the light emission intensity of the light emitting element groups 12-1 to 12-4 is controlled by the second control. adjust. The first control and the second control may be performed at a predetermined cycle, may be performed when an execution instruction is input from the outside, or may be performed by feedback control. . Hereinafter, a case where the first control and the second control are feedback control will be described as an example.

  FIG. 4 is a flowchart showing processing when setting and storing a reference value for the entire light emitting region and a reference value for each divided region in the lighting apparatus according to the embodiment of the present invention.

  In the illumination device according to the embodiment of the present invention, as shown in FIG. 4, for example, in a factory, the luminance distribution and the chromaticity distribution are measured with two-dimensional color luminance (step S1). The light emission intensities of the light emitting element groups 12-1 to 12-4 in each of the divided regions A1 to A4 are optimally adjusted so that the luminance unevenness and the chromaticity unevenness are minimum and the luminance and chromaticity are optimum values. (Step S2). When the light emission intensity of the light emitting element groups 12-1 to 12-4 in each divided area A1 to A4 is optimally adjusted, the light emitting element groups 12-1 to 12- in each divided area are divided for each divided area A1 to A4. Only 4 is turned on, and the light emission intensity at that time is detected by the color sensor 13. This detected value is stored in the storage unit 26 as a reference value when the light emitting element group is turned on for each of the divided areas A1 to A4 (step S3). Further, the light emitting element groups 12-1 to 12-4 in all the divided areas are turned on at the same time, and the light emission intensity at that time is detected by the color sensor 13, and this detection value lights up the light emitting element groups in all the divided areas. It is memorize | stored in the memory | storage part 26 as a reference value at the time of doing (step S4).

  FIG. 5 is a flowchart showing processing when the light emitting element group is turned on for each of the divided areas A1 to A4 in step S3, and a reference value for each divided area is obtained and stored.

  In FIG. 5, the divided region n is initialized to “1”, for example (step S11). When n is “1”, only the light emitting element group 12-1 in the divided area A1 is turned on (step S12), and the light emission intensity at this time is detected by the color sensor 13 (step S13). The detection value of the color sensor 13 is stored in the storage unit 26 as the reference value Ra1 of the divided area A1 (step S14). It is determined whether or not the divided area n has reached the last divided area (for example, “4”) (step S15). If the divided area n has not reached the last divided area, the divided area n is incremented (step S16). ), The process returns to step S12.

  Hereinafter, by repeating the processes of steps S12 to S16, reference values Ra1 to Ra4 when only the light emitting element groups 12-1 to 12-4 are turned on for each of the divided regions A1 to A4 are obtained. These reference values Ra1 to Ra4 are stored in the storage unit 26.

  If it is determined in step S15 that the divided area n has reached the last divided area (for example, “4”), the process ends there.

  FIG. 6 shows a process for obtaining and storing a reference value when the light emitting element groups of all the divided regions in step S4 are turned on.

  In FIG. 6, the light emitting element groups 12-1 to 12-4 in all the light emitting regions are turned on simultaneously (step S21), and the light emission intensity at this time is detected by the color sensor 13 (step S22). The detection value of the color sensor 13 is stored in the storage unit 26 as the reference value Rt for the entire light emitting area (step S23).

  In the lighting device to which the present invention is applied, when the power source of the lighting device is once turned off and then turned on again, the reference values Ra1 to Ra4 for the respective divided regions A1 to A4 obtained as described above are used, 1st control which controls the emitted light intensity of the light emitting element groups 12-1 to 12-4 is performed for every division area A1 to A4. Further, the second control for controlling the light emission intensity of the light emitting element groups 12-1 to 12-4 in the entire region is performed using the reference value Rt for the entire light emitting region obtained as described above. Thereby, the brightness | luminance and chromaticity of the light emission surface of an illuminating device can be maintained in an initial adjustment state.

  FIG. 7 shows the first control process. In FIG. 7, the divided region n is initialized to “1”, for example (step S31). When n is “1”, only the light emitting element group 12-1 in the divided area A1 is turned on (step S32), and the light emission intensity at this time is detected by the color sensor 13 (step S33). Is output as the detection value Da1 (step S34). The reference value Ra1 of the divided area A1 is read from the storage unit 26 (step S35), and the reference value Ra1 and the detected value Da1 are compared (step S36).

  It is determined whether or not the difference between the detected value Da1 and the reference value Ra1 is within the range of the error value e-1 (step S37), and the difference between the detected value Da1 and the reference value Ra1 must be within the range of the error value e-1. For example, it is determined whether or not the detected value Da1 is greater than the reference value Ra1 (step S38). If the detection value Da1 is larger than the reference value Ra1 in step S38, the light emission intensity of the light emitting element group 12-1 in the divided area A1 is lowered (step S39), and the process returns to step S32. If the detection value Da1 is smaller than the reference value Ra1 in step S38, the light emission intensity of the light emitting element group 12-1 in the divided area A1 is increased (step S40), and the process returns to step S32.

  By repeating the above processing, the detection value Da1 approaches the reference value Ra1.

  If it is determined in step S37 that the difference between the detected value Da1 and the reference value Ra1 is within the range of the error value e-1, whether or not the divided area n has reached the last divided area (for example, “4”). Judgment is made (step S41). If the divided area n has not reached the last divided area, the divided area n is incremented (step S42), and the process returns to step S32.

  By repeating the above, the emission intensity adjustment is performed for each of the divided areas A1 to A4 so that the detected values Da1 to Da4 become the reference values Ra1 to Ra4 in the divided areas A1 to A4, respectively. If it is determined in step S41 that n has reached the number of divisions, the process is terminated.

  FIG. 8 shows the second control. In FIG. 8, the light emitting element groups 12-1 to 12-4 in all the divided regions are all turned on (step S51), and the light emission intensity at this time is detected by the color sensor 13 (step S52), and all the light emitting elements are turned on. The detection value Dt is set (step S53). The reference value Rt for all the divided areas is read from the storage unit 26 (step S54), and the reference value Rt is compared with the detected value Dt (step S55).

  It is determined whether or not the difference between the detected value Dt and the reference value Rt is within the range of the error value e-2 (step S56), and the difference between the detected value Dt and the reference value Rt must be within the range of the error value e-2. For example, it is determined whether or not the detected value Dt is larger than the reference value Rt (step S57). If the detection value Dt is larger than the reference value Rt in step S57, the light emission intensity of the light emitting element groups 12-1 to 12-4 is lowered (step S58), and the process returns to step S51. If the detection value Dt is smaller than the reference value Rt in step S57, the light emission intensity of the light emitting element groups 12-1 to 12-4 is increased (step S59), and the process returns to step S51.

  By repeating the above processing, the detection value Dt approaches the reference value Rt. If it is determined in step S56 that the difference between the detected value Dt and the reference value Rt is within the range of the error value e-2, the process is ended.

  As described above, in the lighting device to which the present invention is applied, only one divided area selected from the divided areas A1 to A4 is turned on, and the color sensor 13 detects the emission intensity of each divided area A1 to A4. The detected values at this time are compared with the reference values Ra1 to Ra4, and the light emitting element groups 12-1 to 12-4 in the divided regions A1 to A4 are set so that the detected values coincide with the reference values Ra1 to Ra4. The first control is performed by increasing or decreasing the input power. Further, the light emitting element groups 12-1 to 12-4 in the divided areas A1 to A4 are turned on at the same time, the light intensity of all the divided areas is detected by the color sensor 13, and the detected value at this time is compared with the reference value Rt. The second control is performed by increasing or decreasing the input power of the light emitting element groups 12-1 to 12-4 in all the divided regions A1 to A4 so that the detected value matches the reference value Rt.

  For tasks that require uniform image display for the long time with the same brightness and white color (for example, diagnostic applications in the medical field and color finish confirmation applications in the printing field, etc.), regularly check or calibrate the display quality of the liquid crystal display. By performing the first control and performing the second control during normal use, the liquid crystal display can be used for a long time in the same state as the initial state.

  In addition, when 1st control and 2nd control are feedback control, as shown in FIG. 9, it is possible to perform 1st control and 2nd control alternately.

  As for the first control, one of the divided areas is turned on for each of the divided areas A1 to A4 divided into a plurality of areas, and the light emission intensity in the lighted divided areas is adjusted, and the light emission adjustment with the same light emission intensity is performed. Is performed in each of the divided regions, the adjustment time becomes longer, and the display luminance is partially dark during the adjustment. For this reason, it can be considered that the first control is performed as follows.

(1) The first control is performed according to a user instruction.
(2) The first control is performed during a period when the user does not use the clock function provided in the lighting device.

  Specifically, when the first control is performed according to an instruction from the user, the light emission intensity is adjusted by the first control when the user presses the adjustment button.

  In addition, when the clock function provided in the lighting device is used and the period is not used by the user, a schedule function for automatically managing the power on / off of the display device is installed for the period not used by the user. Therefore, this schedule function is used, and a schedule is built so as to be implemented in the off period of the display device.

  Further, the emission intensity may be adjusted by the first control in accordance with the accumulated lighting time. This is because a first counter that counts the cumulative time that the lighting device is actually turned on and a second counter that counts the cumulative power save time (SUSPEND time) are provided. In the case where the cumulative time of lighting at has reached a predetermined reference time, the light emission intensity is adjusted by the first control.

  Further, in the above-described embodiment, one light emitting area is divided into, for example, four divided areas A1 to A4, and one color sensor 13 is provided for one entire light emitting area. As described above, the divided area composed of the plurality of divided areas A1 to A4 and one color sensor 13 may be used as one unit, and a plurality of these units may be combined to form the entire light emitting area. That is, in FIG. 10, a plurality of divided regions A1-1 to A4-1, A1-2 to A4-2, A1-3 to A4-3, and A1-4 to A4-4 are divided into blocks B1, B2, B3, B4, and these blocks B1 to B4 are combined to form one light emitting region.

  The present invention is not limited to the above-described embodiments, and various modifications and applications can be made without departing from the gist of the present invention.

It is explanatory drawing which shows the outline | summary of the illuminating device of embodiment of this invention. It is a block diagram which shows the structure of the illuminating device of embodiment of this invention. It is a block diagram which shows the structure of the drive circuit of the illuminating device of embodiment of this invention. It is a flowchart used for description of the illuminating device of embodiment of this invention. It is a flowchart used for description of the illuminating device of embodiment of this invention. It is a flowchart used for description of the illuminating device of embodiment of this invention. It is a flowchart used for description of the illuminating device of embodiment of this invention. It is a flowchart used for description of the illuminating device of embodiment of this invention. It is a timing diagram used for description of the illuminating device of embodiment of this invention. It is explanatory drawing of other embodiment of this invention. It is a graph used for description of the conventional illuminating device. It is a graph used for description of the conventional illuminating device. It is a graph used for description of the conventional illuminating device.

Explanation of symbols

11 ... base substrate,
12-1 to 12-4 ... light emitting element group,
13. Color sensor,
21R ... Red LED group,
21G ... Green LED group,
21B ... Blue LED group,
22-1 to 22-4 ... Driving circuit,
23R ... Red LED drive circuit,
23G ... Green LED drive circuit,
23B ... Blue LED drive circuit,
25. Control unit,
26. Storage unit,
A1 to A4 ... divided areas

Claims (6)

Driving means for dividing the light emitting region into a plurality of divided regions and driving the light emitting element for each of the divided regions;
A light intensity detection means provided in common for the plurality of divided regions;
A storage unit that stores a reference value of emission intensity for each divided region when the light emitting element is driven for each divided region;
The light emitting element is driven for each divided region, the light intensity is detected for each divided region by the light intensity detecting means, the detected value of the light intensity for each divided region, and the reference value of the light intensity for each divided region And a control means for performing a first control for controlling the light intensity of the light-emitting element for each of the divided regions based on the comparison result. The storage means stores a reference value of the light intensity of the entire light emitting region when the light emitting element is driven over the entire light emitting region,
The control means drives the light emitting elements in all the divided areas, detects the light intensity of the whole light emitting area by the light intensity detecting means, detects the light intensity of the whole light emitting area and the light of the whole light emitting area. 2. The lighting device according to claim 1, wherein a second control is performed to compare a reference value of intensity and control light intensity of the light emitting element based on the comparison result.   The lighting device according to claim 1, wherein the first control is performed at a predetermined cycle.   2. The divided area composed of the plurality of divided areas and a light intensity detecting means common to the plurality of divided areas is defined as one unit, and a plurality of the units are combined. Lighting equipment. Dividing the light emitting region into a plurality of divided regions, driving the light emitting element for each divided region,
Detecting light intensity with a light intensity detecting means provided in common for the plurality of divided regions,
Reference is made to storage means for storing a reference value of light intensity for each divided area when the light emitting element is driven for each divided area, and the detected value of light intensity for each divided area and the storage means stored in the storage means A control method for an illuminating device, comprising: comparing a light intensity reference value for each divided region and controlling the light intensity of the light emitting element for each divided region based on the comparison result. The storage means stores a reference value of the light intensity of the entire light emitting region when the light emitting element is driven over the entire light emitting region,
Driving the light emitting elements in all the divided areas, detecting the light intensity of the entire light emitting area by the light intensity detecting means, and detecting the light intensity of the entire light emitting area and the reference value of the light intensity of the entire light emitting area; The light intensity of the said light emitting element is controlled based on the said comparison result. The control method of the illuminating device of Claim 5 characterized by the above-mentioned.

Images