JP2012022181A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that color breakup occurs when white balance adjustment is performed by light emission duties in a display device which displays a color image by color mixture of a plurality of different color light emitting elements.SOLUTION: A light emitting device includes a plurality of different color light emitting elements and a driving circuit for driving the light emitting elements, and a color temperature is variably set. The driving circuit controls brightness of each light emitting element on the basis of a supplied brightness signal and controls a light emission duty of the light emitting element on the basis of a supplied light emission period control signal. The brightness signal is common to all of set color temperatures, and the light emission period control signal equalizes light emission duties of the different color light emitting elements at a standard color temperature being one of the set color temperatures and makes the light emission duties of the different color light emitting elements different from each other at color temperatures other than the standard color temperature.

Description

  The present invention relates to a light emitting device such as a self-luminous display device or a lighting device.

  In a display device in which a color image is displayed with a plurality of basic colors typified by three colors of red (R), green (G), and blue (B), a pixel is formed by a combination of display elements that display each basic color. White is displayed when each basic color display element outputs the maximum luminance. A natural white display can be obtained by adjusting the luminance ratio (white balance) of the basic colors.

  The shade of white to be displayed is generally displayed at a color temperature, and is set to a value determined by the standard, such as 5000K, 6500K, 9300K, or a value according to the usage scene. NTSC, which is a typical video signal, is based on the US standard assuming a color temperature of 6500K. Even in the same NTSC, 9300K is specified in Japan. Also in the usage scene, the user may set the computer monitor to 5000K or the like when setting the computer monitor or the like because the lower the color temperature, the less the fatigue caused by the use. As described above, the display used for the monitor is provided with a switch for setting the color temperature and can be switched between several set values.

  The display device is not the only light emitting device that can set the color temperature. Also in the lighting device, light emitting elements of different colors can be arranged and their luminance can be adjusted to produce various mixed colors. Illumination devices include not only general indoor lighting but also backlights of liquid crystal display devices and light sources of endoscopes.

  The color temperature can also be expressed by chromaticity coordinates, and white colors having different color temperatures are arranged on a curve called a black body locus on the chromaticity coordinates. In a display device using RGB as a basic color, the luminance ratio of RGB is adjusted and set so as to come to a predetermined color temperature position on the black body locus. However, in an actual display device or lighting device, white that deviates from the black body locus is also used in order to have a special color rendering effect.

  When a self-luminous display element is used, the luminance ratio of RGB is designed based on the circuit characteristics of the drive circuit, the aperture ratio, and the like in consideration of the luminous efficiency of each color. FIG. 11 is a diagram showing the relationship between gradation and luminance of a display element adjusted to a desired RGB luminance ratio by such a design. In the case of a display device with 64 gradations, a scale from 0 to 63 is engraved on the horizontal axis.

  The data signal given to the display element to obtain the luminance of a predetermined gradation is determined by referring to a table or an arithmetic expression that associates the luminance and the signal given to the display element. This table or calculation formula is called a gamma correction table or gamma correction calculation formula, and is prepared in the gamma adjustment circuit of the control unit.

  In the case of a self-luminous display element, since the materials and configurations of the display elements are different for RGB, even when the same voltage signal (or current signal) is applied to intermediate luminance, different luminance is often obtained. In that case, a RGB gamma correction table or an arithmetic expression is prepared.

  Even if the luminance ratio can be set to a desired value due to the characteristics of the drive circuit and the aperture ratio, once the display device is completed, in addition to adjusting the modulation range of the data signal applied to the display element, that is, the amplitude by RGB, It is difficult to change the luminance ratio for adjusting the color temperature. In order to change the modulation amplitude of the data signal, it is necessary to replace the gamma correction table or the arithmetic expression, resulting in a complicated and large circuit.

In order to solve this problem, Patent Document 1 proposes a display device that achieves white balance by adjusting the light emission periods (light emission duty) of RGB in one frame. Since the visible brightness is determined by time integration of luminance (integrated luminance), the duty ratio is adjusted so that the ratio of integrated luminance becomes the luminance ratios L _R0 , L _G0 , and L _B0 in FIG. , White balance can be taken. The color temperature can also be adjusted by changing the RGB duty ratio. Since the luminance (instantaneous luminance) of each color is not changed, the same gamma correction table or arithmetic expression can be used at different color temperatures.

JP 2006-337561 A

  When white balance is achieved by adjusting the RGB duty, a difference occurs in the light emission times of the three colors RGB in one frame. Due to this time difference, the color of the image to be displayed changes every certain period in the frame, so that when a moving image is displayed, a phenomenon called “color breakup” occurs.

FIG. 12 shows the RGB luminance and the light emission period within one frame in white display in the display device of Patent Document 1. The RGB colors start to emit light simultaneously at time T within one frame period, and are turned off at different times T _E1 , T _E2 , and T _E3 . Therefore, the RGB light emission duties are different. Assuming that the luminance during light emission is the same, the duty ratio determines the ratio of RGB integrated luminance, and the color temperature is determined accordingly.

However, adjusting the white balance at a duty as in Patent Document _1, since different _{T E1,} T E2, T _{E3 respectively,} from _{T E1} to _{T E2} appear yellow, which contaminated with R and _G, and _{T E2} Red is displayed until _TE3 .

  The display color within one frame is different for a short time, but when displaying a moving object, the observer's line of sight follows it and the edge behind the object appears colored yellow and red. End up. This is a phenomenon called “color breakup”, and this phenomenon greatly reduces the image quality of moving images. Color breakup also occurs when a moving object is illuminated and photographed using not only a display device but also an endoscope or other light source having different colors over time.

The present invention is a light emitting device including a plurality of light emitting elements of different colors and a driving circuit for driving the light emitting elements, the color temperature is variably set,
The drive circuit controls the luminance of the light emitting element based on a supplied luminance signal, and controls the light emission duty of the light emitting element based on a supplied light emission period control signal;
The luminance signal is a signal common to all set color temperatures,
The light emission period control signal is equal to a light emission duty of the light emitting elements of different colors at a standard color temperature which is one of the set color temperatures, and the different colors at a color temperature other than the standard color temperature. It is a signal that makes the light emission duty of the light emitting elements different from each other.

  In the present invention, at one of the settable color temperatures, the RGB light emission duties are made equal, and white adjustment is performed according to the luminance ratio. At other color temperatures, the luminance ratio is kept as it is, and color adjustment is performed by changing the light emission duty. As a result, the difference in RGB light emission duty is small, the time required for the light source to produce different colors is shortened, and the color breakup phenomenon is suppressed.

It is a block circuit diagram which shows the structure of the display apparatus of this invention. It is a figure which shows the drive circuit of each organic EL element of RGB. It is a timing chart which shows (a) each light emission timing signal of RGB at the standard color temperature in a 1st Example, and the brightness | luminance and light emission period of (b) organic EL element. It is a timing chart which shows (a) each light emission timing signal of RGB and (b) the brightness | luminance and light emission period of an organic EL element in the color temperature lower than the standard in 1st Example. It is a timing chart which shows (a) each light emission timing signal of RGB and (b) the brightness | luminance and light emission period of an organic EL element in the color temperature higher than the standard in a 1st Example. It is a timing chart which shows the brightness | luminance and light emission period of the RGB organic EL element in the standard color temperature in a 2nd Example. It is a timing chart which shows the brightness | luminance and light emission period of the RGB organic EL element in the color temperature lower than the standard in a 2nd Example. It is a timing chart which shows the brightness | luminance and light emission period of the RGB organic EL element in the color temperature higher than the standard in a 2nd Example. It is a timing chart which shows the brightness | luminance and light emission period of the RGB organic EL element in the color temperature lower than the standard in a 3rd Example. It is a timing chart which shows the brightness | luminance and light emission period of the RGB organic EL element in the color temperature higher than the standard in a 3rd Example. It is a figure which shows a gamma characteristic. It is a timing chart which shows the brightness | luminance and light emission period of the conventional organic EL element.

  FIG. 1 is a block diagram showing a configuration of an organic EL display device 1 according to an embodiment of the present invention.

  The display unit 10 is a region in which drive circuits 11R, 11G, and 11B that drive red (R), green (G), and blue (B) organic EL elements are arranged in a matrix. The organic EL element forms a pixel by combining three colors of RGB, and m pixels in the row direction and n pixels in the column direction are arranged.

  The display unit 10 is provided with scanning lines S1, S2,... Sn for selecting the driving circuits 11R, 11G, and 11B of the organic EL elements in units of rows. A row selection signal is supplied from the scanning line driver 12 to the scanning lines S1, S2,. Depending on the driving circuit of the organic EL element, two or more scanning lines may be provided in each row.

  Data lines DR1, DG1, DB1, DR2,... DBm that connect the drive circuits 11R, 11G, and 11B of the organic EL elements in the column direction are provided so as to cross the scanning lines S1, S2,. The data signal Vdata is supplied from the data line driver 13 to the data lines DR1, DG1, DB1, DR2,. The data line driver 13 converts the data signal Vdata sent serially from the gamma adjustment circuit 16 described later into a parallel signal for each column and sends it to the data line.

  In addition to the scanning line S (hereinafter not a specific row or column, in general description, subscripts for the row and column are omitted) and the data lines DR, DG, DB, the light emission period of the organic EL element Three light emission period control lines TR, TG, and TB are provided for each row. Each of the three light emission period control lines TR, TG, and TB commonly connects the drive circuits for the R, G, and B organic EL elements in one row. A signal is supplied from the light emission period control circuit 14 to the light emission period control lines TR, TG, and TB.

  In addition to this, the display unit 10 is provided with a power supply line for supplying a power supply voltage to the drive circuits 11R, 11G, and 11B, which is omitted in FIG.

  The control unit 19 includes a circuit 15 that sends a signal for controlling each operation to the scanning line driver 12, the data line driver 13, and the light emission period control circuit 14, a gamma adjustment circuit 16, and a light emission timing signal generation circuit 17. . The gamma adjustment circuit 16 takes in the image signal Video, generates a data signal Vdata while referring to the gamma correction tables 20R, 20G, and 20B, and outputs the data signal Vdata to the data line driver 13. The light emission timing signal generation circuit 17 independently determines the RGB light emission periods based on the color temperature information Temp, and sends light emission timing signals ILMr, ILMg, and ILMb corresponding to the light emission timing signals to the light emission period control circuit 14.

  A color temperature setting switch 18 is attached to the display device 1 and can be switched by the user. The color temperature information Temp set by the color temperature setting switch 18 is sent to the light emission timing signal generation circuit 17. The color temperature information Temp may be sent as a signal from the outside of the display device 1.

  2 shows details of the drive circuits 11R, 11G, and 11B associated with the organic EL elements R, G, and B, and the scanning lines S, data lines DR, DG, and DB, and light emission period control lines TR, TG, connected thereto. It is a figure which shows TB.

  The drive circuits 11R, 11G, and 11B hold data signals sent through the drive TFTs 101R, 101G, and 101B that supply current to the organic EL elements R, G, and B and the data lines DR, DG, and DB for one frame, respectively. Capacitors 104R, 104G, 104B are selected in units of rows, and currents flowing through TFTs 102R, 102G, 102B and organic EL elements R, G, B serving as switches for transmitting data signals to the holding capacitors 104R, 104G, 104B are cut off. TFTs 103R, 103G, and 103B serving as light emission period control switches are included.

  The TFT 102 (hereinafter, not a specific color, but in general description, the color suffix is omitted) has a gate connected to the scanning line S and a selection signal (High) sequentially applied to the scanning line for each row. Level) at the same time. The TFT 103 which is a light emission period control switch has a gate connected to the light emission period control line T, and is turned on / off independently for each color.

  When a selection signal (High level) is input to the scanning line S, the gate and source of the driving TFT 101 are short-circuited, and the gate is reset to a potential that does not depend on the previous state. The difference between the reset potential and the data signal potential of the data line D becomes the voltage across the storage capacitor 104. When the selection signal of the scanning line S is not selected (Low level), the switch 102 is turned off (off), and the data signal is held as the voltage across the holding capacitor 104.

  When the row sequential selection signal of the scanning line S is scanned over all rows and the data signal is held in the holding capacitors 104 of all the drive circuits 11, a constant reference potential independent of the data signal is applied to the data line D, A potential obtained by adding the voltage of the storage capacitor 104 to the reference potential is transmitted to the gate of the driving TFT 101. At the same time, the light emission period control switch 103 is turned on, and a current determined by the gate potential of the driving TFT 101 flows to the organic EL element. In response to this current, the organic EL element emits light, and an image corresponding to the input video signal Video is displayed on the display unit 10.

  The light emission period control switch 103 is switched on / off within a period (usually 1/60 seconds) assigned to one frame of video, and determines the light emission duty of the organic EL element.

  In the driving circuit of FIG. 2, a data signal is written in units of rows by a scanning line, and then a reference signal is input from the data line, and the organic EL elements in all rows emit light within the same period. The light emission period control signals are different for the three colors RGB, but are common to all rows for each color.

  On the other hand, there is also a method in which light emission is immediately started for a row in which selection = data signal writing is completed without waiting for completion of selective scanning over all rows. In this case, the light emission period control circuit supplies an independent light emission period control signal to the light emission period control line for each row.

  As described above, the drive circuit is supplied with the data signal, controls the luminance of the display element based on the data signal, and is supplied with the light emission period control signal, and controls the light emission duty based on the control signal. It is. The data signal is a luminance signal that indicates the luminance of each display element in the display device, and the luminance signal that gives the luminance of each light emitting element in accordance with the overall luminance in the lighting device.

  The drive circuit is not limited to that shown in FIG. 2, and any drive circuit, storage capacitor, data write switch, and light emission period control switch may be used. The display element may be a current-driven light emitting element such as an LED other than the organic EL element.

  The light emission timing signal generation circuit 17 determines a light emission period and a pause period within one frame period based on the input color temperature data Temp, and outputs them to the light emission period control circuit 14 as a light emission timing signal ILM. The light emission period control circuit 14 outputs a high level signal corresponding to the light emission period and a low level signal corresponding to the light extinction period to the light emission period control line T.

  When all the rows are in the light emission period at the same time as in the drive circuit of FIG. 2, the outputs ILMr, ILMg, and ILMb of the light emission timing signal generation circuit 17 are directly applied to the light emission period control lines TR, TG, and TB. Output all at once.

  When the light emission periods are row-sequential, the signals ILMr, ILMg, and ILMb from the light emission timing signal generation circuit 17 are delayed one row at a time by a shift register (not shown), and the light emission period control lines TR, TG, TB of each row are delayed. Output to.

  When the light emission period control signal becomes the selection level (High), the light emission period control switch is turned on, and a current flows through the organic EL element to emit light.

  The present invention relates to a light emitting device using a light emitting element such as an organic EL element, in which the color temperature is variable, and the RGB light emission duty is made equal at one of the color temperatures set by the switch 18, and the color temperature is determined by the luminance ratio. To be. At other color temperatures, the luminance ratio is kept as it is, and the color adjustment is performed by changing the light emission duty.

  Hereinafter, the present invention will be described in detail by way of examples.

  A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 3A shows the light emission timing signals ILMr, ILMg, and ILMb that are the outputs of the light emission timing signal generation circuit 17 when the standard color temperature is set, and FIG. 3B shows the same. It is a figure which shows the light emission luminance and light emission period of the RGB organic EL element of the pixel which displays white. A period in which the vertical axis is at the zero level indicates a light extinction period, and a period in which the vertical axis is positive indicates a period in which light is emitted with the luminance.

Within one frame from T ₀ to T _1, the remaining period Te after the end of the scanning = writing period Tw is a period assigned to light emission. The ILMr, ILMg, and ILMb signals are at the high level during the period from T2 to T3, and this is repeated every frame.

  The same timing signal is sent from the light emission period control circuit 14 to the light emission period control lines TR, TG, TB in response to the signals ILMr, ILMg, ILMb. This signal may be issued simultaneously for all rows or may be issued row-sequentially depending on the method of the drive circuit. When the signals are output sequentially in rows, they are output to each row as a signal delayed by one row by a shift register (negative illustration) of the light emission period control circuit 14.

In response to the signals of the light emission period control lines TR, TG, TB, the RGB organic EL elements in each row emit light from the same time T2 to T3. During the light emission period, each organic EL element emits light with a luminance corresponding to the data signal Vdata sent from the data lines DR, DG, DB to each pixel. In this case, since the maximum gradation signal white signal or RGB is retained in the organic EL elements, the organic EL element emits light maximum brightness L _R, L _G, in L _B.

Adjustment of whiteness (white balance) is performed by the color brightness _{L R, L G, L B} . Displaying intermediate color and brightness non-white display, the brightness L _R, L _G, smaller than L _B. The data signal Vdata corresponding to the given luminance is generated by the gamma adjustment circuit 16. In the gamma adjustment circuit 16, RGB gradation levels of each pixel are extracted from the input video signal Video, and the data signal Vdata is determined with reference to the gamma characteristic table. Since the gamma characteristics are different for RGB, respective gamma characteristic tables are prepared.

  FIG. 4A shows the light emission timing signals ILMr, ILMg, and ILMb when the color temperature is set lower than the standard color temperature, and FIG. 4B shows the luminance and light emission timing of white display at the same time. It is.

  In order to display white with a low color temperature, the R emission start time is set to T2R earlier than T2, and the end time is set to T3R later than T3. That is, the light emission duty of R (the ratio of the light emission time in one frame period or unit time) is larger than the light emission duty at the standard color temperature. On the other hand, the start and end times of G emission are T2 and T3, respectively, which are the same as those at the standard color temperature. In the B light emission, the start time is T2B later than T2, and the end time is T3B earlier than T3. That is, the light emission duty of B is lower than the light emission duty at the standard color temperature.

As shown in FIG. 4B, the RGB organic EL elements emit light at the respective luminances during the same period as the light emission timing signals ILMr, ILMg, and ILMb. RGB brightness of pixels displaying white, the same as the brightness _{L R, L G, L B} in the standard color temperature in FIG. 3 (b). Brightness perceived by the eyes, that is, luminance × light emission time (hereinafter referred to as integral luminance), R increases, G does not change, and B decreases compared to that at the standard color temperature. As a result, white that is reddish, that is, low in color temperature is displayed.

  For the display of intermediate luminance, the same data signal Vdata is generated using the same gamma correction table used by the gamma adjustment circuit 16 at the standard color temperature, and sent to the data line D through the data line driver 13. Accordingly, the luminance of the organic EL element is the same as that at the standard color temperature for any gradation, and the color temperature is adjusted only by the difference in the light emission duty.

  In order not to change the brightness of the whole white, the increase in the integral luminance of R and the decrease in the integral luminance of B cancel each other, and the total sum of the RGB integral luminances becomes equal to the value at the standard color temperature. May be. At that time, the light emission period of G may be finely adjusted as necessary.

  FIG. 5A shows the light emission timing signals ILMr, ILMg, ILMb when the color temperature is set higher than the standard color temperature, and FIG. 5B shows the luminance and light emission timing of white display at the same time. It is.

In order to display white with a high color temperature, the light emission of R is T2R ′ whose start time is later than T2, and T3R ′ whose end time is earlier than T3. The start time and end time of G light emission do not change from the standard color temperature, and B light emission has a start time T2B ′ earlier than T2 and an end time T3B ′ later than T3. That is, the light emission time of B is longer than the light emission time at the standard color temperature. As a result, white which is bluish, that is, has a high color temperature is displayed. Each color brightness _{L R, L G, L B} is the same as the luminance at the standard color temperature.

  Even at a color temperature higher than the standard, white and halftone luminances are made the same as those at the standard color temperature, and white balance is obtained by the light emission duty of FIG. Since the data signal corresponding to the luminance does not change, the same gamma correction table 20 as that at the standard color temperature can be used, and it is not necessary to prepare a different gamma correction table for each color temperature.

  As the standard color temperature, one color temperature is selected from the range of color temperatures that can be selected by the user. One of the color temperatures that can be selected by the user is the standard color temperature, the RGB duty is made equal at that color temperature, and the brightness is adjusted to achieve white balance, so the user changes the color temperature from there. However, the difference in duty is kept small, and color breakup is hardly a problem.

  On the other hand, when the luminance of RGB is made equal and white balance is obtained only by the duty, the difference in the duty of RGB is large at any color temperature, and there is a high possibility that color breakup occurs.

  Of the several color temperatures that can be selected, if the color temperature near the center is selected as the standard color temperature, it is only necessary to slightly change the duty on both the high temperature side and the low temperature side. When the color temperature selectable by the user is four types of 5000K, 6000K, 7000K, and 8000K, it is preferable to set 6000K or 7000K as a standard.

As mentioned above, even when the color temperature other than the standard color temperature is set, the maximum brightness L _R, L _G, since L _B and the intermediate brightness is not changed from the time of standard color temperature, the data signals Vdata are all The color temperature is the same. As a result, the gamma correction table 20 used in the gamma adjustment circuit 16 does not need to be changed for each color temperature, and may be one for each RGB.

  In this embodiment, the color temperature is switched by changing both the RGB light emission start time T2 and the end time T3. However, the light emission start time T2 may be aligned with RGB and only the light emission end time T3 may be changed. . Conversely, the color temperature may be adjusted by changing the light emission start time T2 while keeping the light emission end time T3 constant.

  In the illumination device, there is no frame period assigned to one image, but the ratio of the time during which light is emitted within a unit time is the light emission duty. A data signal corresponds to a luminance adjustment signal.

  6 to 8 are diagrams for explaining a second embodiment of the present invention. 6-8, only the chart of the light emission luminance and the light emission time of the organic EL element is shown, and the chart of the light emission timing signal is omitted.

  FIG. 6 is a light emission timing chart of each RGB organic EL element at a standard color temperature. In Example 1, the organic EL element emits light once in one frame period, but in this example, each organic EL element emits light multiple times in one frame. The rest is the same as in the first embodiment.

The organic EL element emits light intermittently within one frame from T ₀ to T _{1 according} to the light emission time control signal.

When the standard color temperature is set, the light emission start and end times, the rest periods of ΔT _R , ΔT _G , and ΔT _B and the rest positions T _B1 , T _B2 , and T _B3 are the same for RGB. Adjustment of whiteness (white balance) is performed by the ratio of the luminance _{L R, L G, L B} . By reducing the intensity of each color for _{L R, L G, L B} , and displays the halftone. The ratio of the luminance to the gradation level is determined with reference to the gamma characteristic table for each RGB.

FIG. 7 shows a white display state when the white balance is changed and switched to another color temperature lower than the standard color temperature. To set the low temperature side than the standard value color temperature, rest period R [Delta] T R _'was smaller than [Delta] T _R, rest period [Delta] T _G of G is about the same, [Delta] T _B' to set the larger than [Delta] T _B . As a result, the duty of R increases and the duty of B decreases. However, in order not to change the visible white brightness, the sum of the integrated luminances for RGB is the same as that for the standard color temperature. As a result, the integral luminance within one frame of R increases, and the integral luminance of B decreases, resulting in a reddish white.

FIG. 8 is a diagram showing the light emission timing of each color when the color temperature is set higher than the standard. Rest position _{T B1, T B2, T B3} , and the peak luminance _{L R,} L G, _{L B} is not changed from the setting of the standard color temperature, the suspension period [Delta] T _R 'for R made larger than [Delta] T _R of the R Duty , The idle period ΔT _G of _G is substantially the same, and the idle period ΔT _B ′ of _B is made smaller than ΔT _B to increase the blue duty. The integrated luminance of R is relatively smaller than B, and a bluish white is displayed.

  In the present embodiment, since the light emission is performed in a plurality of times within one frame, the occurrence of color breakup is further suppressed as compared with the first embodiment.

  9 to 10 are diagrams for explaining a third embodiment of the present invention.

  In Example 2, the color temperature is adjusted by extending or shortening the pause period. However, the color temperature can be adjusted by changing the number of times of light emission within one frame.

  The luminance and time of light emission at the standard color temperature are the same as in FIG. FIG. 9 is a diagram showing a change in the number of times of light emission when the standard color temperature is shifted to a low temperature side, and FIG. 10 is a graph showing a change in the number of light emissions when the standard color temperature is shifted to a low temperature side.

When switched to the low-temperature side color temperature from the standard color temperature, as shown in FIG. 9, to shorten the rest period R from [Delta] T _R to [Delta] T R _', rest period [Delta] T _G of G is unchanged, rest period B Extend ΔT _B to ΔT _B '. Further, the central time of the rest periods of R and B is changed so that the number of times of light emission within one frame period is increased by R once, G remains unchanged, and B decreases by one. _{That, n R ⇒n R '+ 1} , n G ⇒n G', and _{n B ⇒n B} '-1. As a result, the integrated luminance of R increases, the integrated luminance of G does not change, and the integrated luminance of B decreases, so that it becomes reddish white. However, it is preferable to adjust the R and B emission periods once so that the total RGB luminance does not change so that the R luminance increase and the B luminance decrease cancel each other.

  When the standard color temperature is switched to the high temperature side, as shown in FIG. 10, the R pause period is lengthened, the G pause period is not changed, the B pause period is shortened, and the number of times of light emission within one frame period is reduced. , R is decreased once, G is not changed, and B is increased once. As a result, a bluish white is obtained.

DESCRIPTION OF SYMBOLS 1 Display apparatus 12 Scan line driver 13 Data line driver 14 Light emission period control circuit 16 Gamma adjustment circuit 17 Light emission timing signal generation circuit 18 Color temperature setting switch 19 Control part 20R, 20G, 20B Gamma characteristic table Video Video signal Temp Color temperature signal ILMr , ILMg, ILMb Light emission timing signal Vdata Data signal S1, S2 ... Sn Scan line DR1, DG1 ... DBm Data line TR1, TG1 ... TBn Light emission period control line

Claims (7)

A light emitting device including a plurality of light emitting elements of different colors and a driving circuit for driving the light emitting elements, wherein the color temperature is variably set,
The drive circuit controls the luminance of the light emitting element based on a supplied luminance signal, and controls the light emission duty of the light emitting element based on a supplied light emission period control signal;
The luminance signal is a signal common to all set color temperatures,
The light emission period control signal is equal to a light emission duty of the light emitting elements of different colors at a standard color temperature which is one of the set color temperatures, and the different colors at a color temperature other than the standard color temperature. A light emitting device characterized in that the light emitting duty is different from each other.   The light emitting elements of different colors are light emitting elements of three colors of red, green, and blue, and at a color temperature lower than the standard color temperature, the light emitting duty of the red light emitting element is that of the blue light emitting element. 2. The light emitting device according to claim 1, wherein a light emission duty of the red light emitting element is smaller than a light emission duty of the blue light emitting element at a color temperature larger than the light emission duty and higher than the standard color temperature.   The light emitting device according to claim 1, wherein the standard color temperature is a color temperature at the center of the variably set color temperature range or a color temperature closest to the center.   The light-emitting device according to claim 1, wherein the light-emitting device is a display device.   The light emitting device according to claim 4, wherein each of the light emitting elements of different colors emits light a plurality of times in one frame period.   5. The light emitting device according to claim 4, wherein the number of times of light emission within one frame period of the light emitting elements of different colors is equal at the standard color temperature and is different from each other at a color temperature other than the standard color temperature.   The light-emitting device according to claim 1, wherein the light-emitting device is a lighting device.