JP2008185924A - Illuminating apparatus and image projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illuminating apparatus of low power consumption, giving consideration to a light emission efficiency difference due to characteristic variation and deterioration of every LED, and to provide an image projector equipped with the illuminating apparatus. <P>SOLUTION: The illuminating apparatus includes: a light source means having a plurality of light emitting diodes 101, 102, 103, 201, 202, 203, 301, 302 and 303 according to colors of illuminating light; a light quantity control means that controls the current value of a current to be supplied to each light emitting diode of the light source means; an emitted light quantity storage means that stores the emitted light quantity of each light emitting diode when the current of the prescribed value is supplied to each light emitting diode of the light source means; and an efficiency sensitivity calculating means that calculates the efficiency sensitivity as the change ratio of the emitted light quantity of each light emitting diode to the current value of the current supplied to each light emitting diode. The light quantity control means controls the current value of the current to be supplied to each light emitting diode based on the efficiency sensitivity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illuminating device and an image projecting device, and more particularly to an illuminating device using a plurality of light emitting diodes and an image projecting device including the illuminating device.

  2. Description of the Related Art In recent years, projectors using LEDs that emit red (R), green (G), and blue (B) light as light sources have been developed due to higher output and higher efficiency of light emitting diodes (LEDs). When direct-current driving such a light source using a plurality of LEDs, the amount of light is changed by increasing or decreasing the current level flowing through the LED. However, if the ambient temperature or the amount of heat generated by the LED itself changes, the current level is kept constant. Even if feedback control is performed, the amount of light emitted from each LED varies. Even when the same current is applied to LEDs of the same color, the amount of light emitted from each LED varies due to characteristic variations and deterioration due to long-term use. As a result, there is a problem that the white balance of the image projected from the projector is lost or color misregistration occurs in RGB color mixture.

Therefore, in a conventional projection display device (projector), a reference white signal is projected and its chromaticity is detected, and when the white balance is lost, the number of LED elements is controlled for each color to be lit, etc. Thus, the white balance is controlled (see, for example, Patent Document 1).
Japanese Patent Laying-Open No. 2005-121688 (first page, FIG. 1)

  However, in the conventional projection display device (see, for example, Patent Document 1), white balance control with high light use efficiency is realized by controlling the number of LED elements to be lit. Thus, there is a problem that a sufficient power reduction effect cannot always be obtained.

  The present invention has been made in view of the above-described problems, and a low power consumption illumination device that takes into account differences in light emission efficiency due to characteristic variations and deterioration of each LED, and an image projection device including the illumination device. The purpose is to provide.

  An illumination device according to the present invention emits a plurality of illumination lights of different colors, and has a light source means having a plurality of light emitting diodes for each color of the illumination light, and a current value of a current supplied to each light emitting diode of the light source means. Controls the light intensity control means for increasing or decreasing the amount of illumination light emitted from the light source means for each color, and stores the light emission amount of each light emitting diode when a predetermined current is supplied to each light emitting diode of the light source means Efficiency sensitivity that is the rate of change of the light emission amount of each light emitting diode with respect to the current value of the current supplied to each light emitting diode based on the light emission amount of each light emitting diode stored in the light emission amount storage means The light quantity control means controls the current value of the current supplied to each light emitting diode based on the efficiency sensitivity.

  Further, in the illumination device according to the present invention, the light emission amount storage means described above, for each light emitting diode of the light source means, the light emission amount of each light emitting diode when the current value of the current supplied to each light emitting diode is changed, It memorize | stores for every electric current value of the electric current supplied to each light emitting diode.

  The illumination device according to the present invention further includes a temperature sensor for detecting the temperature of the light source means, and the light emission amount storage means has a light emitting diode for each light emitting diode when the temperature of the light source means changes for each light emitting diode of the light source means. The light emission amount is stored for each temperature, and the efficiency sensitivity calculating means calculates the efficiency sensitivity using the detected temperature detected by the temperature sensor.

  In the illumination device according to the present invention, the efficiency sensitivity calculating unit may calculate a predetermined alternating current when a predetermined direct current and a predetermined alternating current superimposed on the direct current are supplied to each light emitting diode of the light source unit. As a ratio between the amplitude and the amplitude of the light emission amount of each light emitting diode, efficiency sensitivity at a current value of a predetermined direct current is calculated.

  The illumination device according to the present invention emits a plurality of different colors of illumination light, and includes a light source unit having a plurality of light emitting diodes for each color of the illumination light, and a current value of a current supplied to each light emitting diode of the light source unit. And a light amount control means for increasing or decreasing the amount of illumination light emitted from the light source means for each color, and an efficiency that is a change rate of the light emission amount of each light emitting diode with respect to the current value of the current supplied to each light emitting diode And an efficiency sensitivity storage means for storing the sensitivity, wherein the light quantity control means controls the current value of the current supplied to each light emitting diode based on the efficiency sensitivity.

  In the illumination device according to the present invention, when the light quantity control means reduces the light quantity of the illumination light of a certain color emitted from the light source means, the light emitting diode of the color has the lowest efficiency sensitivity. When the current value of the supplied current is decreased and the amount of illumination light of a certain color emitted from the light source means is increased, the current supplied to the one with the highest efficiency sensitivity among the light emitting diodes of that color The current value is increased.

  In the illumination device according to the present invention, when the light amount control means reduces the light amount of illumination light of a certain color emitted from the light source means, the efficiency sensitivity among the light emitting diodes of that color is different from the other light emitting diodes. If there is a plurality of devices having lower efficiency and equal efficiency sensitivity, the current values of the currents supplied to the light emitting diodes are decreased while maintaining the same efficiency sensitivity. When increasing the amount of illumination light, if there are multiple light emitting diodes of that color that have higher efficiency sensitivity than other light emitting diodes and equal efficiency sensitivity, the current supplied to those light emitting diodes The current value is increased while maintaining the state where the efficiency sensitivities are equal.

  An image projection apparatus according to the present invention includes any one of the above-described illumination apparatuses, spatial modulation means that spatially modulates illumination light emitted from the illumination apparatus based on an input image signal, and illumination that is spatially modulated by the spatial modulation means And projection optical means for projecting light.

  The lighting device according to the present invention includes a light emission amount storage unit that stores a light emission amount of each light emitting diode when a predetermined current is supplied to each light emitting diode of the light source unit, and each light emission stored in the light emission amount storage unit. An efficiency sensitivity calculating means for calculating an efficiency sensitivity which is a rate of change of the light emission amount of each light emitting diode with respect to a current value of a current supplied to each light emitting diode, based on the light emission amount of the diode, and the light quantity control means has an efficiency Since the current value of the current supplied to each light emitting diode is controlled based on the sensitivity, the light emission amount of the light emitting diode with high efficiency sensitivity is given priority to increase, and the light emission amount of the light emitting diode with low efficiency sensitivity is given priority to decrease. By doing so, it becomes possible to reduce the power consumption (current) of the entire lighting device.

  Hereinafter, an illumination device and an image projection device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating an overall configuration of an image projection apparatus including an illumination apparatus according to an embodiment of the present invention. In FIG. 1, a three-panel liquid crystal panel projector is shown as an example of the image projector. However, the illumination device according to the present invention may be used for other types of image projectors (projectors).

  The image projection apparatus shown in FIG. 1 has an image signal processing unit 10, and an analog RGB signal from a personal computer or the like, or an image signal from a television (NTSC) or the like is input to the image signal processing unit 10. The image signal processing unit 10 performs synchronization separation, Y / C separation, IP conversion, scaling (resolution conversion), color (color matrix) conversion, trapezoid (keystone) on the input image signal according to the signal form of the input image signal. Processing such as correction is performed to generate digital image data. This digital image data is sent to the panel drivers 14r, 14g, and 14b of the display panels 12r, 12g, and 12b provided for each of the RGB colors, and the panel drivers 14r, 14g, and 14b digitally display the display panels 12r, 12g, and 12b. Drive based on image data. As a result, RGB images are formed on the display panels 12r, 12g, and 12b. In the present embodiment, it is assumed that the three display panels 12r, 12g, and 12b are each composed of a liquid crystal panel.

  In addition, the image projection apparatus according to the present embodiment includes a light source 16 that emits red (R), green (G), and blue (B) illumination light. The light source 16 includes a plurality of light emitting diodes (hereinafter referred to as LEDs) for each of the RGB colors. The LEDs 101, 102, and 103 that emit R light are R-LED light sources, and the LED 201 that emits G light. 202 and 203 constitute a G-LED light source, and LEDs 301, 302 and 303 emitting B light constitute a B-LED light source. The LEDs 101, 102, and 103 constituting the R-LED light source have the cathode side connected to the FETs 111, 112, and 113, respectively, and the anode side connected to the R power source for the R-LED light source. Similarly, the LEDs 201, 202, and 203 constituting the G-LED light source and the 301, 302, and 303 constituting the B-LED light source have the cathode side connected to the FET and the anode side connected to the power source. Here, the RGB LED, the FET connected to the LED, and the power source are referred to as the light source 16. In the present embodiment, the light source 16 includes three LEDs for each RGB color. However, for example, two or four or more LEDs may be used for each RGB color, and each RGB color may be used. The number of LEDs may be different.

  The gate of the FET connected to each LED of the light source 16 is connected to the LED light emission timing control unit 18, and this LED light emission timing control unit 18 is connected to the CPU 20. CPU20 produces | generates the timing signal which controls the light emission timing of each LED of the light source 16, and sends this timing signal to each LED. Each LED of the light source 16 is connected to a current control circuit unit 22 via an FET, and this current control circuit unit 22 is connected to an LED light emission current control unit 26 via a DA converter 24. The LED light emission current control unit 26 is connected to the CPU 20, and the LED light emission current control unit 26 controls the light emission amount of each LED by controlling the current value of the current supplied to each LED according to a command from the CPU 20. Although only the current control circuit unit 22 for the R-LED light source is shown in FIG. 1, it is assumed that the G-LED light source and the B-LED light source are also connected to the current control circuit unit.

  Light from the R-LED light source, G-LED light source, and B-LED light source is synthesized and shaped for each color by illumination optical systems 28r, 28g, and 28b constituted by, for example, integrator rods, and displayed on the display panels 12r, 12g, and 12b. Is guided to. Light from the illumination optical systems 28r, 28g, and 28b is spatially modulated by the display panels 12r, 12g, and 12b, and an image generated thereby is guided to the projection optical system 30. The projection optical system 30 synthesizes each color image generated by the display panels 12r, 12g, and 12b into an RGB mixed color image, and projects the image onto a screen (not shown) or the like outside the image projection apparatus.

  The CPU 20 is connected to a memory 32 and a user interface 34. The memory 32 stores a current value-light emission amount table and the like shown below, and the user interface 34 receives a light quantity setting instruction from the user and the like, Is sent to the CPU 20. In the present embodiment, a feature amount extraction unit 36 is connected to the image signal processing unit 10 and the CPU 20. The feature amount extraction unit 36 receives the input image signal from the image signal processing unit 10, determines the maximum and minimum luminance values, the average luminance level (APL), and the like for the image, and sends the values to the CPU 20. Note that the feature amount extraction unit 36 is not necessarily provided, but the CPU 20 automatically sets, for example, the light amount of the light source 16 according to the average luminance level determined by the feature amount extraction unit 36 instead of setting by the user. You may do it.

  Further, the image projection apparatus according to the present embodiment includes temperature sensors 38r, 38g, and 38b that detect the temperature of the light source 16 for each of the R-LED light source, the G-LED light source, and the B-LED light source, the R-LED light source, and the G-LED. Light amount sensors 40r, 40g, and 40b that detect the amount of illumination light emitted from the LED light source and the B-LED light source and passed through the illumination optical systems 28r, 28g, and 28b are provided for each color. The temperature sensors 38r, 38g, and 38b are, for example, the vicinity of an R-LED light source, a G-LED light source, and a B-LED light source, or a heat sink if the image projection apparatus is an air-cooled type, and water-cooled if a water-cooled type. Can be attached to a jacket. Note that only one temperature sensor may be attached to the light source 16. The light quantity sensors 40r, 40g, and 40b can be attached to the emission ends of the illumination optical systems 28r, 28g, and 28b, for example, and move to the center of the emission ends of the illumination optical systems 28r, 28g, and 28b when acquiring light quantity data. It can be constituted as follows. The temperature sensors 38r, 38g, and 38b send the detected temperature data to the CPU 20, and the light quantity sensors 40r, 40g, and 40b send the detected light quantity data to the CPU 20.

  In the image projection apparatus according to the present embodiment, the light source 16, the LED light emission timing control unit 18, the CPU 20, the current control circuit unit 22, the DA converter 24, the LED light emission current control unit 26, the memory 32, and the temperature sensors 38r, 38g, and 38b. The light quantity sensors 40r, 40g, and 40b function as an illumination device for projecting an image.

  In the present embodiment, first, a current value-light emission amount table is created for each LED of the light source 16 by calibration and stored in the memory 32. This current value-light emission amount table is data in which the light emission amount of each LED when the current value of the current supplied to each LED of the light source 16 is changed is recorded for each current value of the current supplied to each LED. This is a table, and can be obtained, for example, by applying a current to each light emitting diode of the light source 16 with a constant step width and detecting the light emission amount at that time by the light quantity sensors 40r, 40g, 40b. As will be described later, the CPU 20 calculates the efficiency sensitivity, which is the rate of change of the light emission amount of each LED with respect to the current value of the current supplied to each LED, from this current value-light emission amount table, and the illumination light emitted from the light source 16 When the amount of light is increased or decreased for each color, the total drive power consumption of the light source 16, that is, the current value of the current supplied to each LED is controlled so as to minimize the total current based on this efficiency sensitivity.

  FIG. 2 is a flowchart showing a calibration procedure for obtaining a current value-light emission amount table. An example of the current value-emission amount table obtained by the procedure of FIG. 2 is shown in FIG.

  First, when a user inputs a calibration start command from the user interface 34, a signal for starting creation of a current value-light emission amount table for each LED of the light source 16 is sent to the CPU 20 (S101).

  The CPU 20 that has received a signal for starting the creation of the current value-emission amount table masks the image signal so that no image or the like with noise is displayed during the creation of the current value-emission amount table. (S102). This is to prevent an image of an inappropriate color or an uncomfortable image due to a change in the amount of light from being displayed during the acquisition of the light emission amount data. For example, a specific image such as a logo or a blue back is output. The digital image signal data is sent to the panel drivers 14r, 14g, and 14b.

  And the LED light emission timing control part 18 produces | generates the timing signal for acquiring the light emission amount of each LED of the light source 16 for every LED by the instruction | indication from CPU20 (S103). FIG. 3 is a diagram illustrating an example of a timing signal generated by the LED light emission timing control unit 18. 3 shows a case where the light source 16 has eight LEDs (R1, R2,..., R8, G1, G2,..., G8, B1, B2,..., B8) for each RGB color. As shown in FIG. 3, the LED light emission timing control unit 18 generates a gate pulse signal in which the timing is shifted for each LED for each color as a timing signal in order to detect the light emission amount for each current value of each LED. In the example of FIG. 3, gate pulse signals are generated in the order of R1, R2,... R8 for the R LEDs, and similar gate pulse signals are generated for G and B. The timing signal generated by the LED light emission timing control unit 18 is sent to each LED such as the LEDs 101, 102, and 103 via the FETs 111, 112, and 113.

  Moreover, the LED light emission current control part 26 changes the electric current value of the electric current supplied to each LED by the instruction | indication from CPU20, for example for every predetermined step (S104). At this time, the LED light emission current control unit 26 acquires, for example, data for increasing the current value supplied to each LED within a use condition range for each predetermined step in order to obtain the light emission amount at different current values for each LED. Output. Data output from the LED light emission current control unit 26 is converted into an analog signal by the DA converter 24 and input to the current control circuit unit 22, FETs 111, 112, 113, and the like. The FETs 111, 112, 113, etc. supply a current having a current value corresponding to the input analog signal to each LED, such as the LEDs 101, 102, 103. That is, an LED that emits light is selected based on the timing signal generated by the LED light emission timing control unit 18, and the current value of the current supplied to each LED is controlled by data output from the LED light emission current control unit 26. .

  Then, the light emission amount of each LED that emits light at the timing and set current value as described above is detected by the light amount sensors 40r, 40g, and 40b for each current value (S105). The detected light emission amount of each LED is sent to the CPU 20.

  At the same time as detecting the light emission amount of each LED, the temperatures of the R-LED light source, G-LED light source and B-LED light source are also detected by the temperature sensors 38r, 38g and 38b (S106). Note that the light emission amount of each LED may be detected for each current value in a plurality of temperature states, and a current value-light emission amount table for each temperature may be created for each LED. For example, the detection of the light emission amount of each LED as described above can be performed a plurality of times, and the current value-light emission amount table of each LED at different temperatures can be stored in the memory. The detected temperature data of the R-LED light source, G-LED light source, and B-LED light source is sent to the CPU 20.

  Then, the light emission amount of each LED and the temperatures of the R-LED light source, G-LED light source, and B-LED light source sent to the CPU 20 as described above are the current value-light emission amount table for each LED as shown in FIG. Is stored in the memory 32 (S107). At this time, the light emission amount data at different temperatures can be stored as another current value-light emission amount table.

  Finally, the mask process performed in S102 is canceled and the calibration is completed (S108).

  Note that this calibration may be performed after the elapse of a predetermined use time, for example, when the user starts the image projection apparatus for the first time in the factory shipping adjustment process. In particular, when the user performs calibration every predetermined usage time and updates or adds the current value-light emission amount table of the memory 32, the accuracy of the light amount control described later can be further improved.

  FIG. 4 is a diagram illustrating an example in which a current value-light emission amount table obtained by calibration is graphed. The current value-light emission amount table shown in FIG. 4 is obtained by the calibration shown in FIG. In the example shown in FIG. 4, it is assumed that the R-LED light source of the light source 16 includes three LEDs R1, R2, and R3, and a current value-light emission amount table for these three LEDs. In FIG. 4, the current value-light emission amount table (characteristic curve) for R1 is shown as Lr1, the current value-light emission amount table for R2 is Lr2, and the current value-light emission amount table for R3 is shown as Lr3.

The light emission amounts when current of current value Ia is supplied to R1, R2, and R3 are La1, La2, and La3, respectively, and current of current value Ib obtained by adding a predetermined current value to current value Ia is supplied. The light emission amounts at that time are Lb1, Lb2, and Lb3, respectively. Here, assuming that the slopes of the current value-light emission amount tables (characteristic curves) of R1, R2, and R3 between the current values Ia and Ib are k1, k2, and k3, respectively.
k1 = (Lb1-La1) / (Ib-Ia)
k2 = (Lb2-La2) / (Ib-Ia)
k3 = (Lb3-La3) / (Ib-Ia)
It becomes. In the present embodiment, the inclinations k1, k2, and k3 are referred to as the efficiency sensitivity of each LED. This efficiency sensitivity can also be defined as the rate of change of the light emission amount of each LED with respect to the current value of the current supplied to each LED. In the example shown in FIG. 4, the magnitude relationship between the efficiency sensitivities k1, k2, and k3 between the current values Ia and Ib is k1>k2> k3.

  In the present embodiment, the CPU 20 reads the current value-light emission amount table of each LED stored in the memory 32, and calculates the efficiency sensitivity at each current value for each LED. In the example of FIG. 4, only the LED of the R-LED light source is taken as an example, but the CPU 20 calculates the efficiency sensitivity for each LED of the G-LED light source and the B-LED light source in the same manner. In this embodiment, only the current value-emission amount table of each LED is stored in the memory 32. However, both the current value-emission amount table and the efficiency sensitivity at each current value may be stored. Good.

  Further, in the example of FIG. 4, the efficiency sensitivity of each LED is obtained by increasing the current value from Ia to Ib. For example, the efficiency sensitivity may be obtained as a slope when the current value is decreased. Therefore, the efficiency sensitivity may be obtained as a slope between data before and after the same step width.

  FIG. 5 is a graph showing another method for obtaining the efficiency sensitivity of each LED. In the example shown in FIG. 5, as in the example of FIG. 4, the R-LED light source of the light source 16 includes three LEDs R 1, R 2, and R 3, and FIG. FIG. 5B shows the light emission amount, the current value of R2 versus the light emission amount, and FIG. 5C shows the current value of R3 versus the light emission amount. In FIGS. 5A, 5B, and 5C, the characteristic curve for R1 (same as the current value-emission amount table) is Lr1, and the characteristic curve for R2 is the characteristic for Lr2 and R3. The curve is indicated by Lr3.

In the example of FIG. 5, a direct current having a current value Ic and an alternating current having an amplitude Id superimposed on the direct current are supplied to R1, R2, and R3. Assuming that the amplitudes of the light emission amounts of R1, R2, and R3 at this time are Ld1, Ld2, and Ld3, respectively, the efficiency sensitivities k1, k2, and k3 of R1, R2, and R3 at the current value Ic are the AC current amplitude Id and each LED. It is calculated | required as a ratio of the amplitude of light emission amount. That is,
k1 = Ld1 / Id
k2 = Ld2 / Id
k3 = Ld3 / Id
Thus, the inclination along the characteristic curve (current value-emission amount table) is obtained as in the example of FIG. In addition, when calculating | requiring the efficiency sensitivity of each LED using the method shown in FIG. 5, it is not necessary to perform the calibration for creating a current value-light-emission amount table as shown in FIG. The efficiency sensitivity may be stored in the memory 32.

  In this way, a predetermined direct current and a predetermined alternating current superimposed on the direct current are supplied to each LED to detect the light emission amount at that time, and the ratio between the amplitude of the alternating current and the amplitude of the light emission amount of each LED is obtained. The efficiency sensitivity at the current value of the direct current can be calculated.

  FIG. 6 is a graph showing an example of the current value-light emission amount table and the corresponding efficiency sensitivity. In the example of FIG. 6, it is assumed that the R-LED light source of the light source 16 includes three LEDs R1, R2, and R3. The current value-light emission amount table for R1 is Lr1, the current value-light emission amount table for R2 is Lr2, the current value-light emission amount table for R3 is Lr3, and the amount of light emitted from the R-LED light source is shown. This is indicated by Lr (= Lr1 + Lr2 + Lr3). However, it is assumed that the current values supplied to R1, R2, and R3 are the same for the light amount Lr. FIG. 6B is a graph showing the efficiency sensitivity calculated from the current value-emission amount table of FIG. 6A, and the efficiency sensitivities of R1, R2, and R3 are indicated by k1, k2, and k3, respectively. Yes. In the example of FIG. 6, the maximum current value that can be supplied to R1, R2, and R3 is Im, and the efficiency sensitivity of R1, R2, and R3 when the current value is Im is K1, K2, and K3, respectively. The efficiency sensitivities of R1, R2, and R3 when K is 0 are K1 ′, K2 ′, and K3 ′, respectively. In the example of FIG. 6, it is assumed that K3 <K2 <K1 <K3 ′ <K2 ′ <K1 ′ for convenience.

  FIG. 7 is a graph for explaining the light amount control method of the lighting apparatus according to the present embodiment. FIGS. 7A to 7F are graphs of the same efficiency sensitivity as FIG. 6B, and show the same R-LED light source as in FIG.

  In an illumination device used in a conventional image projection device, for example, when the light amount of an R-LED light source is reduced from 100% (a state in which all LEDs emit light at a maximum current value) to 50%, it is supplied to each LED. The current value is uniformly reduced in a state where the current values of the generated currents are equal, and the amount of light emitted from the R-LED light source is reduced.

  On the other hand, in this embodiment, for example, when increasing or decreasing the amount of light emitted from the R-LED light source, the current value supplied to each LED based on the efficiency sensitivity of each LED calculated in FIG. 4 or FIG. To control the amount of light emitted from each LED. Specifically, for example, when the amount of light emitted from the R-LED light source is decreased, the current value of the current supplied in order from the LED having low efficiency sensitivity is decreased. In this embodiment, when increasing or decreasing the amount of light emitted from the LED light source of each color, the CPU 20 first grasps the current light emission amount of each LED based on the light amount data of the light amount sensors 40r, 40g, and 40b, and from there, The light emission amount of the LED is increased or decreased to a target light amount.

  Hereinafter, a control sequence for reducing the amount of light emitted from the R-LED light source in the present embodiment will be described with reference to FIGS. 7A to 7C. FIG. 7A shows an initial state, and in this initial state, the light amount of the R-LED light source is 100% (a state where R1, R2, and R3 all emit light at the maximum current value Im). Shall.

  First, as indicated by a circle in FIG. 7A, the current value of R3 having the lowest efficiency sensitivity at this time is lowered from the state where R1, R2, and R3 emit light at the maximum current value Im, and the efficiency of R3 is reduced. The light emission amount of R3 is decreased until the sensitivity k3 becomes K2 (a in FIG. 7A).

  When the efficiency sensitivities k3 and k2 of R3 and R2 become equal at K2, as indicated by the circles and triangles in FIG. 7 (b), the efficiency sensitivities k3 and k2 of R3 and R2 are kept equal while R3 and R2 The current value is decreased, and the light emission amounts of R3 and R2 are decreased until the efficiency sensitivities k3 and k2 of R3 and R2 become K1 (bc and de in FIG. 7B). When this control is generalized and applied to an R-LED light source having four or more LEDs, the efficiency sensitivity of the LEDs of the R-LED light source is lower than that of other LEDs (here, R1) and the efficiency sensitivity is lower. When there are a plurality of equal values (here, R3 and R2), the current values of the currents supplied to the LEDs are decreased while their efficiency sensitivities are kept equal.

  Then, when the efficiency sensitivities k3, k2, and k1 of R3, R2, and R1 are equal to K1, the efficiency sensitivities k3, k2, and k1 of R3, R2, and R1, as indicated by circles, triangles, and squares in FIG. While maintaining the same state, the current values of R3, R2, and R1 are decreased to 0 to decrease the light emission amounts of R3, R2, and R1 (fgh in FIG. 7C). Here, when the current value of R3 becomes 0, the current values of R2 and R1 are lowered until the current value of R2 becomes 0 while keeping the efficiency sensitivities k2 and k1 of R2 and R1 equal (FIG. 7C). I−j) When the current value of R2 becomes 0, the current value of R1 is decreased until the current value of R1 becomes 0 (n in FIG. 7C).

  Next, a control sequence for increasing the amount of light emitted from the R-LED light source in the present embodiment will be described with reference to FIGS. 7 (d) to 7 (f). When increasing the amount of light emitted from the R-LED light source, in order to increase the current value of the current supplied in order from the LED with high efficiency sensitivity, basically, the order is the reverse of the case where the amount of light is decreased. Become. FIG. 7D shows an initial state. In this initial state, the light amount of the R-LED light source is 0% (the current values of R1, R2, and R3 are all 0).

  First, as shown by the square in FIG. 7D, the current value of R1, which has the highest efficiency sensitivity at this time, is increased from the state where the current values of R1, R2, and R3 are 0, and the efficiency sensitivity k1 of R1 is K2 The light emission amount of R1 is increased until “′” (a in FIG. 7D).

  When the efficiency sensitivities k1 and k2 of R1 and R2 become equal at K2 ′, the efficiency sensitivities k1 and k2 of R1 and R2 are kept equal as shown by the squares and triangles in FIG. 7D. And the light emission amounts of R1 and R2 are increased until the efficiency sensitivities k1 and k2 of R1 and R2 become K3 ′ (bc and de in FIG. 7D). When this control is generalized and applied to an R-LED light source having four or more LEDs, the efficiency sensitivity of the LEDs of the R-LED light source is higher than that of other LEDs (here, R3) and the efficiency sensitivity is higher. When there are a plurality of equal values (here, R1 and R2), the current values of the currents supplied to the LEDs are increased while their efficiency sensitivities are kept equal.

  Then, when the efficiency sensitivities k1, k2, and k3 of R1, R2, and R3 are equal to K3 ′, the efficiency sensitivities k1, k2, and R1, R2, and R3 of R1, R2, and R3 as shown by squares, triangles, and circles in FIG. While maintaining the same state of k3, the maximum current values of R1, R2, and R3 are increased to Im to increase the light emission amounts of R1, R2, and R3 (fgh in FIG. 7D). Here, when the current value of R1 becomes Im, the current values of R2 and R3 are increased until the current value of R2 becomes Im while maintaining the equal sensitivity sensitivities k2 and k3 of R2 and R3 (FIG. 7 (e)). Hi, jn), when the current value of R2 becomes Im, the current value of R3 is increased until the current value of R3 becomes Im (p in FIG. 7 (f)).

  FIG. 8 is a graph showing another example of the current value-light emission amount table and the corresponding efficiency sensitivity. In the example of FIG. 8, it is assumed that the R-LED light source of the light source 16 includes three LEDs R1, R2, and R3 as in the example of FIG. The current value-light emission amount table for R1 is Lr1, the current value-light emission amount table for R2 is Lr2, the current value-light emission amount table for R3 is Lr3, and the amount of light emitted from the R-LED light source is shown. This is indicated by Lr (= Lr1 + Lr2 + Lr3). However, it is assumed that the current values supplied to R1, R2, and R3 are the same for the light amount Lr. Further, FIG. 8B is a graph showing the efficiency sensitivity calculated from the current value-emission amount table of FIG. 8A, and the efficiency sensitivities of R1, R2, and R3 are indicated by k1, k2, and k3, respectively. Yes. In the example of FIG. 8, Im is the maximum current value that can be supplied to R1, R2, and R3.

  In the example of FIG. 8, as shown in FIG. 8A, the slopes (efficiency sensitivity) from the current value 0 to the point A of Lr1, Lr2, and Lr3 are the same and constant, and this slope is shown in FIG. ) Is shown as efficiency sensitivity K4. The slopes of the region where the current value is larger than the point B of Lr1, the region where the current value is larger than the point C of Lr2, and the region where the current value is larger than the point D of Lr3 are the same and constant. Is shown as efficiency sensitivity K5 in FIG. The points corresponding to point A, point B, point C, and point D in FIG. 8A are shown as point A ′, point B ′, point C ′, and point D ′ in FIG. 8B, respectively. .

  FIG. 9 is a graph for explaining another example of the light amount control method of the lighting apparatus according to the present embodiment. 9 (a) to 9 (f) are graphs of the same efficiency sensitivity as FIG. 8 (b), and show the same R-LED light source as in FIG.

  Hereinafter, a control sequence for reducing the amount of light emitted from the R-LED light source in the example of FIG. 8B will be described with reference to FIGS. 9A to 9C. FIG. 9A shows an initial state. In this initial state, the light amount of the R-LED light source is 100% (the state where R1, R2, and R3 all emit light at the maximum current value Im). Shall. The basic concept of the light amount control is the same as that in the case of FIG. 7, and the current value of the current supplied in order from the LED with low efficiency sensitivity is decreased.

  First, as indicated by squares, triangles, and circles in FIG. 9A, the current values of R3, R2, and R1 are uniformly lowered to the point B ′ from the state where R3, R2, and R1 emit light at the maximum current value Im. Thus, the light emission amounts of R3, R2, and R1 are decreased (abc in FIG. 9A). At this time, the efficiency sensitivities k3, k2, and k1 of R3, R2, and R1 maintain the state of K5.

  Then, as indicated by squares and triangles in FIG. 9A, the current values of R3 and R2 are uniformly lowered from the point B ′ to the point C ′ to reduce the light emission amounts of R3 and R2 (FIG. 9A). D-e). At this time, the efficiency sensitivities k3 and k2 of R3 and R2 are still in the state of K5.

  Then, as indicated by the square in FIG. 9A, the current value of R3 is lowered from the point C ′ to the point D ′ (f in FIG. 9A). At this time, the efficiency sensitivity k3 of R3 is still in the state of K5.

  Here, when the current value of R3 reaches the point D ′, as indicated by the squares, triangles, and circles in FIG. 9B, the efficiency sensitivities k3, k2, and k1 of R3, R2, and R1 are kept equal to R3. , R2 and R1 are lowered to the point A ′ to reduce the light emission amounts of R3, R2 and R1 (g-i, j-np in FIG. 9B). As a result, the efficiency sensitivities k3, k2, and k1 of R3, R2, and R1 become K4.

  Finally, as indicated by the squares, triangles, and circles in FIG. 9C, the current values of R3, R2, and R1 are uniformly reduced from point A ′ to 0 to decrease the light emission amounts of R3, R2, and R1. (Q, s, t in FIG. 9C). At this time, the efficiency sensitivities k3, k2, and k1 of R3, R2, and R1 are K4.

  Next, a control sequence for increasing the amount of light emitted from the R-LED light source in the example of FIG. 8B will be described with reference to FIGS. 9D to 9F. In this case as well, the basic idea is the same as in FIG. 7, and the current value of the current supplied in order from the LED with high efficiency sensitivity is increased. FIG. 9D shows an initial state. In this initial state, the light amount of the R-LED light source is 0% (the current values of R1, R2, and R3 are all 0).

  First, as indicated by circles, triangles, and squares in FIG. 9D, the current values of R1, R2, and R3 are uniformly increased from 0 to the point A ′ to increase the light emission amounts of R1, R2, and R3. (A, b, c in FIG. 9D). At this time, the efficiency sensitivities k1, k2, and k3 of R1, R2, and R3 are K4.

  Then, as indicated by the circles, triangles, and squares in FIG. 9 (e), the current values of R1, R2, and R3 are changed to points B ′, R3, R2, and R3 while maintaining the same efficiency sensitivities k1, k2, and k3, respectively. The light emission amount of R1, R2, and R3 is increased up to point C ′ and point D ′ (d−e−f and g−h−i in FIG. 9B). Thereby, the efficiency sensitivities k1, k2, and k3 of R1, R2, and R3 become K5.

  Then, as indicated by the square in FIG. 9 (f), the current value of R3 is increased from point D ′ to point C ′ (j in FIG. 9 (f)).

  Then, as indicated by triangles and squares in FIG. 9 (f), the current values of R2 and R3 are uniformly increased from point C ′ to point B ′ to increase the light emission amounts of R2 and R3 (FIG. 9 (a)). N-p).

  Finally, as indicated by circles, triangles, and squares in FIG. 9 (f), the current values of R1, R2, and R3 are uniformly increased from the point B ′ to the maximum current value Im, and the light emission amounts of R1, R2, and R3 are increased. Increase (qst in FIG. 9 (f)).

  7 and 9, the light amount control is performed using the efficiency sensitivity in one temperature state. For example, a current value-light emission amount table at a plurality of temperatures is created by the calibration shown in FIG. The light amount control may be performed using the efficiency sensitivity calculated from the current value-light emission amount table for a near temperature. The temperature of the R-LED light source when performing light quantity control can be detected by the temperature sensor 38r.

  FIG. 10 is a graph showing a current value-light emission amount table and a corresponding efficiency sensitivity for an R-LED light source. In FIG. 10, it is assumed that the R-LED light source includes three LEDs R1, R2, and R3. FIG. 10A shows a current value-light emission amount table for R1 as Lr1, a current value-light emission amount table for R2, Lr2, and a current value-light emission amount table for R3 as Lr3. FIG. 10B shows the efficiency sensitivities of R1, R2, and R3 calculated from the current value-light emission amount table of FIG. 10A by k1, k2, and k3, respectively.

The current value-light emission amount tables Lr1, Lr2, and Lr3 shown in FIG. 10A are expressed by the following formula where the supplied current value is I (the light emission amount is an arbitrary unit).
Lr1 = −0.0000099I ² + 0.0485I−1.08855
Lr2 = −0.00000824I ² + 0.03957I−0.6947
Lr3 = −0.000005966I ² + 0.032036I−0.6222
The maximum current values of R1, R2, and R3 are all 2000 mA. If a current of 2000 mA is supplied to all of R1, R2, and R3, the amount of light emitted from the R-LED light source is 141.38. The amount of light from the R-LED light source is 100%. Here, consider a case where the light quantity of the R-LED light source is reduced to 106.03 (= 141.38 × 0.75), which is 75%.

  When the current value of each LED is uniformly reduced with the current value of each LED being equal as in the prior art, and the light amount of the R-LED light source is reduced to 75%, the current values of R1, R2, and R3 are 1185 mA, and the total current is 3555 mA.

  On the other hand, when the light amount control based on the efficiency sensitivity shown in FIGS. 7 and 9 is performed to reduce the light amount of the R-LED light source to 75%, the current values of R1, R2, and R3 are 1410 mA, 1150 mA, and 960 mA, respectively. The total current is 3520 mA.

  Further, when the light amount of the R-LED light source is reduced to 70.69, which is 50%, when the current value is uniformly reduced with the current value of each LED being equal as in the prior art, the current values of R1, R2, and R3 Is 705 mA, and the total current is 2115 mA. On the other hand, when the light amount control based on the efficiency sensitivity according to the present embodiment is performed, the current values of R1, R2, and R3 are 1030 mA, 695 mA, and 335 mA, respectively, and the total current is 2060 mA.

  Further, when the light amount of the R-LED light source is reduced to 35.346, which is 25%, when the current value of each LED is uniformly reduced with the current value of each LED being equal, current values of R1, R2, and R3 Is 340 mA, and the total current is 1020 mA. On the other hand, when the light amount control based on the efficiency sensitivity according to the present embodiment is performed, the current values of R1, R2, and R3 are 665 mA, 260 mA, and 0 mA, respectively, and the total current is 925 mA.

  Thus, by performing light quantity control based on the efficiency sensitivity according to the present embodiment, it becomes possible to reduce the power consumption (total current) of the light source.

  In the present embodiment, the CPU 20 reads the current value-emission amount table stored in the memory 32, calculates the efficiency sensitivity of each LED, and controls the current value supplied to each LED based on this efficiency sensitivity. It is possible to obtain an illumination device and an image projection device with low power consumption in consideration of the light emission efficiency of each LED.

  Needless to say, the present invention is not limited to the above-described embodiments, and includes various modifications and improvements that can be made within the scope of the technical idea. For example, in the above-described embodiment, the illumination device that mainly drives the LED by direct current has been described, but the present invention can also be applied to an illumination device that drives the LED in pulses. In the above-described embodiment, the light amount control of the R-LED light source has been described as an example. However, the same light amount control can be performed with the G-LED light source and the B-LED light source. The illumination device described in the above embodiment can be applied not only to an image projection device such as a liquid crystal projector but also to a display device such as a liquid crystal display.

It is a block diagram which shows the whole structure of the image projector provided with the illuminating device which concerns on embodiment of this invention. It is the flowchart which showed the procedure of the calibration for acquiring an electric current value-light-emission amount table. It is the figure which showed the example of the timing signal which an LED light emission timing control part produces | generates at the time of calibration. It is a figure which shows the example which graphed the electric current value-light-emission-amount table obtained by calibration. It is the graph which showed the other method of calculating | requiring the efficiency sensitivity of each LED. It is the graph which showed the example of the current value-light-emission-amount table and the efficiency sensitivity corresponding to it. It is a graph for demonstrating the light quantity control method of the illuminating device which concerns on this embodiment. It is the graph which showed the other example of the current value-light-emission amount table and the efficiency sensitivity corresponding to it. It is a graph for demonstrating the other example of the light quantity control method of the illuminating device which concerns on this embodiment. It is the graph which showed the electric current value-light-emission-amount table about a certain R-LED light source, and the corresponding efficiency sensitivity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image signal processing part 12r, 12g, 12b Display panel 14r, 14g, 14b Panel driver 16 Light source 18 LED light emission timing control part 20 CPU
22 Current control circuit unit 24 DA converter 26 LED light emission current control unit 28r, 28g, 28b Illumination optical system 30 Projection optical system 32 Memory 34 User interface 36 Feature amount extraction unit 38r, 38g, 38b Temperature sensor 40r, 40g, 40b Light quantity sensor 101, 102, 103 R-LED
201, 202, 203 G-LED
301, 302, 303 B-LED
111, 112, 113 FET

Claims (8)

Light source means for emitting illumination light of different colors, and having a plurality of light emitting diodes for each color of the illumination light;
A light amount control means for controlling the current value of the current supplied to each light emitting diode of the light source means to increase or decrease the amount of illumination light emitted from the light source means for each color;
A light emission amount storage means for storing the light emission amount of each light emitting diode when a current of a predetermined value is supplied to each light emitting diode of the light source means;
Based on the light emission amount of each light emitting diode stored in the light emission amount storage means, the efficiency sensitivity which is the rate of change of the light emission amount of each light emitting diode with respect to the current value of the current supplied to each light emitting diode is calculated. Efficiency sensitivity calculation means;
With
The illumination device according to claim 1, wherein the light amount control means controls a current value of a current supplied to each light emitting diode based on the efficiency sensitivity.   The light emission amount storage means supplies the light emission amount of each light emitting diode when the current value of the current supplied to each light emitting diode is changed for each light emitting diode of the light source means to each light emitting diode. The illuminating device according to claim 1, wherein the illuminating device is stored for each current value of the current. A temperature sensor for detecting the temperature of the light source means;
The light emission amount storage means stores, for each light emitting diode of the light source means, the light emission amount of each light emitting diode when the temperature of the light source means changes for each temperature, and the efficiency sensitivity calculation means includes the temperature The lighting device according to claim 2, wherein the efficiency sensitivity is calculated using a detected temperature detected by a sensor.   The efficiency sensitivity calculating means is configured to detect the amplitude of the predetermined alternating current and the light emission of each light emitting diode when a predetermined direct current and a predetermined alternating current superimposed on the direct current are supplied to each light emitting diode of the light source means. The lighting device according to claim 1, wherein the efficiency sensitivity at a current value of the predetermined direct current is calculated as a ratio of amplitudes of quantities. Light source means for emitting illumination light of different colors, and having a plurality of light emitting diodes for each color of the illumination light;
A light amount control means for controlling the current value of the current supplied to each light emitting diode of the light source means to increase or decrease the amount of illumination light emitted from the light source means for each color;
Efficiency sensitivity storage means for storing efficiency sensitivity which is a rate of change of the light emission amount of each light emitting diode with respect to a current value of a current supplied to each light emitting diode;
With
The illumination device according to claim 1, wherein the light amount control means controls a current value of a current supplied to each light emitting diode based on the efficiency sensitivity.   When the light amount control means reduces the amount of illumination light of a certain color emitted from the light source means, the light amount control means determines the current value of the current supplied to the light emitting diode of the color having the lowest efficiency sensitivity. When increasing the amount of illumination light of a certain color emitted from the light source means, increasing the current value of the current supplied to the light emitting diode of the color with the highest efficiency sensitivity The lighting device according to any one of claims 1 to 5, wherein   When the light quantity control means reduces the light quantity of the illumination light of a certain color emitted from the light source means, the efficiency sensitivity is lower than the other light emitting diodes among the light emitting diodes of that color, and the efficiency sensitivity is low. When there are a plurality of equal ones, the current values of the currents supplied to the light-emitting diodes are reduced while maintaining the efficiency sensitivities equal, and the amount of illumination light of a certain color emitted from the light source means is reduced. When there are a plurality of light emitting diodes of the color having the efficiency sensitivity higher than those of other light emitting diodes and the same efficiency sensitivity, the current value of the current supplied to the light emitting diodes is increased. The lighting device according to claim 6, wherein the efficiency sensitivities are increased while maintaining an equal state. The lighting device according to any one of claims 1 to 7,
Spatial modulation means for spatially modulating illumination light emitted from the illumination device based on an input image signal;
Projection optical means for projecting illumination light spatially modulated by the spatial modulation means;
An image projection apparatus comprising: