JP2009081353A - Light-emitting device, electronic apparatus and method of controlling light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide flexibility to timing for measuring luminous intensity. <P>SOLUTION: A backlight 300 includes a LED 500R emitting red light, a LED 500G emitting green light and a LED 500B emitting blue light. A driving circuit 550 drives each of LEDs. A control circuit 600A includes a peak hold circuit which holds the maximum value for each luminous intensity signal and outputs each maximum luminous intensity signal for each emitted light color, and compares the value of each maximum luminous intensity signal with each reference value prescribed for each emitted light color, and further so controls the driving circuit 550 that the value of each maximum luminous intensity signal approach each reference value based on comparison results. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light-emitting device including a plurality of types of light-emitting elements that emit light of different colors, a control method thereof, and an electronic apparatus.

  In a direct-view display device typified by a liquid crystal display, a color display is performed by selectively changing the transmittance of white backlight light using a liquid crystal and passing it through a color filter, and RGB without using a color filter. There is a time sequential (field sequential) method in which color display is performed by sequentially emitting light sources of colors and controlling the liquid crystal at a corresponding time timing.

  In the color filter method, the backlight, which has always been turned on for the purpose of reducing the power consumption and improving the moving image characteristics, is dimmed according to the brightness of the display image or blinked in pulses. In general, a light emitting diode (hereinafter referred to as an LED) is used as a light source for such an application. LED has advantages such as longer life, lower power consumption, smaller size, richer colors that can be expressed, faster response speed, and mercury-less than other light sources, but the emission wavelength changes due to heat generation. There is a need to. In general, PWM driving is used to adjust the luminance.

On the other hand, in the case of the time sequential method, in principle, the light source emits light intermittently, but in order to keep the color synthesized on the time axis by the RGB color LEDs, it is based on the sensor as in the color filter method. Feedback control is required. Japanese Patent Application Laid-Open No. H10-228688 discloses a technique for taking in an output of a detection element that detects emission intensity at a constant timing through a low-pass filter and performing feedback control using this result.
JP 2004-163527 A

By the way, in the backlight used for the liquid crystal display device, it is necessary to adjust the light amount of the backlight according to the brightness of the environment. In this case, the period during which the LED emits light is normally PWM-controlled. In such a case, the period during which the LED emits light changes.
In the feedback control described in Patent Document 1, since the emission intensity is captured at a fixed timing, it is not possible to cope with a change in the emission timing required for the liquid crystal display. In addition, the sensor used for the above purpose is sensitive to the wavelength of the light source, but since a low-pass filter is inserted for noise removal, the response has a first order lag characteristic. Therefore, it is necessary to capture the output after the response of the detection element is completed, but the method of Patent Document 1 cannot cope with this situation.

  The present invention has been made in view of such circumstances, and a light emitting device capable of providing a degree of freedom in detection timing of light emission intensity when detecting light emission intensity of a light emitting element and performing feedback control, A control method and an electronic device are provided.

  In order to solve the above-described problems, a light-emitting device according to the present invention includes a plurality of types of light-emitting elements that emit light of different colors, a driving unit that drives each of the plurality of types of light-emitting elements, and the plurality of types of light-emitting elements. A plurality of emission intensity detecting means for measuring the emission intensity of each of the elements to generate a plurality of emission intensity signals; and holding a maximum value for each of the plurality of emission intensity signals for each of the plurality of types of light emitting elements. A plurality of peak hold means for outputting a maximum emission intensity signal, each of the maximum emission intensity signal and each reference value determined for each of the plurality of types of light emitting elements, respectively, and based on the comparison result, Control means (for example, the drive signal generation circuit of the embodiment) for controlling the drive means so that the value of the maximum emission intensity signal matches each reference value is provided.

  According to this invention, since the peak hold means for holding the maximum value of the light emission intensity of each light emitting element is provided, even when the light emitting element is repeatedly turned on and off, the light emission intensity at the time of lighting can be held as the maximum light emission intensity. it can. Since feedback control is executed based on the maximum light emission intensity, the degree of freedom of timing for detecting the light emission intensity can be greatly expanded. In addition, since the peak hold means functions as an integrator, an averaged output with less noise can be obtained by the filter effect. Note that “so as to match” is a concept that includes a predetermined error that occurs in feedback control or the like as well as a case where they completely match.

Next, another light-emitting device according to the present invention includes a plurality of types of light-emitting elements that emit light of different colors, a driving unit that drives each of the plurality of types of light-emitting elements, and light emission intensities of the plurality of types of light-emitting elements. A plurality of emission intensity detecting means for measuring each of the plurality of emission intensity signals, a selection means for sequentially selecting one of the plurality of emission intensity signals and outputting a selected emission intensity signal, and the selection Peak hold means for holding the maximum value of the light intensity signal and outputting the maximum emission intensity signal, and a reference corresponding to the maximum emission intensity signal from a plurality of reference values determined for each of the plurality of types of light emitting elements Control means for selecting a value, comparing the maximum emission intensity signal with the selected reference value, and controlling the driving means so that the value of the maximum emission intensity signal matches the reference value based on the comparison result And with It is characterized in.
According to the present invention, since the selection means is provided, the peak hold means, the comparison means, and the control means can be shared by a plurality of types of light emitting elements. Therefore, the configuration of the light emitting device can be simplified.

In the light emitting device described above, it is preferable that each of the plurality of emission intensity detecting means has a wavelength sensitivity characteristic corresponding to a peak wavelength of light emitted from the plurality of types of light emitting elements.
Next, the electronic device according to the present invention preferably includes the above-described light emitting device as a light source. Such electronic devices include personal computers, mobile phones, projectors, and the like.

  Next, a method for controlling a light-emitting device according to the present invention is a method for controlling a light-emitting device including a plurality of types of light-emitting elements, each of which emits light in a different color. A plurality of emission intensity signals are generated by measurement, a maximum value is held for each of the plurality of emission intensity signals, and each maximum emission intensity signal is generated for each of the plurality of types of light emitting elements. The signal value and each reference value determined for each of the plurality of types of light emitting elements are respectively compared, and the plurality of types are set so that the value of each maximum emission intensity signal matches the reference value based on the comparison result. Each light emitting element is driven. According to the present invention, even when the light emitting element is repeatedly turned on / off, the light emission intensity at the time of lighting can be maintained as the maximum light emission intensity. Since feedback control is executed based on the maximum light emission intensity, the degree of freedom of timing for detecting the light emission intensity can be greatly expanded. In addition, since the peak hold means functions as an integrator, an averaged output with less noise can be obtained by the filter effect.

Next, a method for controlling a light-emitting device according to the present invention is a method for controlling a light-emitting device including a plurality of types of light-emitting elements, each of which emits light in a different color. A plurality of emission intensity signals are generated by measurement, one of the plurality of emission intensity signals is sequentially selected to generate a selected emission intensity signal, and the maximum light emission is maintained while holding the maximum value of the selected light intensity signal. An intensity signal is generated, a reference value corresponding to the maximum emission intensity signal is selected from a plurality of reference values determined for each of the plurality of types of light emitting elements, and the maximum emission intensity signal and the selected reference value are selected. And the plurality of types of light emitting elements are each driven so that the value of the maximum light emission intensity signal matches the reference value based on the comparison result.
According to the present invention, since one of the plurality of light emission intensity signals is sequentially selected to generate the selected light emission intensity signal, time division processing is possible. As a result, peak hold processing, comparison processing, and control processing can be shared by a plurality of types of light emitting elements.

The best mode for carrying out the present invention will be described below with reference to the drawings.
<1. First Embodiment>
<1-1: Overall configuration>
First, the configuration and the like of the liquid crystal display device according to the present embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram schematically showing the basic configuration of the liquid crystal display device according to this embodiment. 2 is a cross-sectional view taken along the plane ZZ ′ in FIG.

As shown in FIG. 1, the liquid crystal display device 1 according to this embodiment includes a liquid crystal panel AA, a backlight 300 having a backlight module 400 and a light emitting module 500, a drive circuit 550, and a control circuit 600A. Has been. A specific example of the lighting device according to the present invention is configured by the light emitting module 500.
In the liquid crystal panel AA, an element substrate 151 and a color filter substrate disposed to face the element substrate 151 are bonded together via a frame-shaped sealing material, and liquid crystal is sealed inside the sealing material to form a liquid crystal 155. This layer is formed. The liquid crystal used for the layer of the liquid crystal 155 is, for example, a TN (Twisted Neematic) type liquid crystal. A backlight 300 is provided on the outer surface of the element substrate 151 of the liquid crystal panel AA. The details of the liquid crystal panel AA will be described later.

The backlight module 400 includes a light emission intensity sensor 401 that measures the light emission intensity of the LED at a plurality of wavelengths, an optical element for uniformly guiding the light emitted and emitted from the LED to the liquid crystal panel AA, and a reflection surface. ing. Further, light having a plurality of types of wavelengths emitted and emitted from the light emitting module 500 is mixed. Note that the light emission intensity sensor 401 measures the light emission intensity for each of the red, green, and blue wavelengths corresponding to the apex of the color reproduction range (in RGB space) required as the performance of the liquid crystal display device 1.
The light emitting module 500 includes a red LED 500R, a green LED 500G, a blue LED 500B, a temperature measuring sensor 501 that measures the temperature of the LED, and a heat radiating means (not shown) that radiates the heat generated by each LED. Here, the symbols “R”, “G”, and “B” of the LEDs represent the emission colors.

Each LED is PWM driven (Pulse Width Modulation drive) with a constant current value by the drive circuit 550. Since the wavelength of light emitted from each LED changes depending on the ambient temperature around the LED, the driving condition of each LED is changed based on the temperature detected by the temperature measurement sensor 501 or the like under the control of the control circuit 600A. It is driven while.
The drive circuit 550 drives a plurality of types of LEDs under a plurality of types of driving conditions. The drive circuit 550 operates in accordance with the control signal supplied from the control circuit 600A, and drives each LED so that, for example, a voltage is generated in each LED at the timing when the enable signal is validated (activated). In particular, the value of the current flowing through each LED may be determined by setting an external resistor or an internal resistor.

  The control circuit 600A changes drive conditions such as drive timing in the drive circuit 550 based on the emission intensity at a plurality of wavelengths measured by the emission intensity sensor and the temperature measured by the temperature measurement sensor 501, and The operation of the drive circuit 550 is controlled.

Next, the overall configuration of the liquid crystal panel according to the electrical configuration described above will be described with reference to FIG. 2 in addition to FIG. 1 described above.
As shown in FIGS. 1 and 2, the liquid crystal panel AA includes an element substrate 151 such as glass or semiconductor on which the pixel electrodes 6 are formed, and a transparent counter substrate 152 such as glass on which the common electrode 158 is formed. And a liquid crystal 155 as an electro-optic material is sealed in this gap while keeping a certain gap with a sealing material 154 mixed with a spacer 153 so that the electrode forming surfaces face each other. Yes. Note that the sealant 154 is formed along the periphery of the counter substrate 152, but a part thereof is opened to enclose the liquid crystal 155. Therefore, after the liquid crystal 155 is sealed, the opening is sealed with the sealing material 156.

Here, on the opposite surface of the element substrate 151 and on the outer side of the sealing material 154, the above-described data line driving circuit 200 is formed to drive a data line (not shown) extending in the Y direction. It has become. Further, a plurality of connection electrodes 157 are formed on this side.
The connection electrode 157 is configured to receive various signals from a timing generation circuit provided outside and an image signal designating RGB gradations. Further, a scanning line driving circuit 100 is formed on one side adjacent to the one side, and the scanning line 2 extending in the X direction is driven from both sides. On the other hand, the common electrode 158 of the counter substrate 152 is electrically connected to the element substrate 151 by a conductive material provided in at least one of the four corners of the bonding portion with the element substrate 151. In addition, the counter substrate 152 is provided with, for example, a color filter arranged in a stripe shape, a mosaic shape, a triangle shape, or the like according to the use of the liquid crystal panel AA. And a black matrix such as resin black in which carbon or titanium is dispersed in a photoresist, and third, a backlight for irradiating the liquid crystal panel AA with light. Particularly in the case of color light modulation, a black matrix is provided on the counter substrate 152 without forming a color filter.

  In addition, the opposing surfaces of the element substrate 151 and the counter substrate 152 are each provided with an alignment film or the like that is rubbed in a predetermined direction, and a polarizing plate (not shown) corresponding to the alignment direction on each back side. Are provided respectively. However, if a polymer-dispersed liquid crystal dispersed as fine particles in a polymer is used as the liquid crystal 155, the above-described alignment film, polarizing plate, and the like are not required. This is advantageous in terms of reducing power consumption.

  Instead of forming part or all of the peripheral circuits such as the data line driving circuit 200 and the scanning line driving circuit 100 on the element substrate 151, for example, for driving mounted on a film using a TAB (TapeAutomate dBonding) technique. The IC chip may be configured to be electrically and mechanically connected via an anisotropic conductive film provided at a predetermined position of the element substrate 151, or the driving IC chip itself may be used using COG (ChipOnGlass) technology. In addition, it may be configured to be electrically and mechanically connected to a predetermined position of the element substrate 151 through an anisotropic conductive film.

<1-2: Configuration of backlight>
Next, the backlight according to the present embodiment will be described in detail with reference to FIGS. FIG. 3 shows a detailed configuration of the light emission intensity sensor 401 according to the present embodiment. The emission intensity sensor 401 includes an R emission intensity sensor 401R, a G emission intensity sensor 401G, and a B emission intensity sensor 401B. The R emission intensity sensor 401R measures the emission intensity at the R peak wavelength and generates an R emission intensity signal Lr indicating the measurement result, and the G emission intensity sensor 401G measures the emission intensity at the G peak wavelength. The G emission intensity signal Lg indicating the measurement result is generated, and the B emission intensity sensor 401B measures the emission intensity at the peak wavelength of the B color and generates the B emission intensity signal Lb indicating the measurement result.

  The R emission intensity sensor 401R includes an R filter 401r having a maximum transmittance at the peak wavelength of the R color and a photodiode 420 through which light enters through the R filter 401r. The anode of the photodiode 420 is grounded, and the cathode is connected to the negative input terminal of the operational amplifier 430. The output signal of the operational amplifier 430 is fed back to the negative input terminal via the resistor 450 and the capacitor 440. For this reason, an imaginary short is established between the negative input terminal of the operational amplifier 430 and the positive input terminal to which the reference voltage Vref is supplied. Therefore, the reference voltage Vref is supplied to the cathode of the photodiode 420. For this reason, the photodiode 420 is reverse-biased. When light enters through the R filter 401r, a current having a magnitude corresponding to the amount of light flows through the photodiode 420. The operational amplifier 430 converts this current into a voltage to generate an R emission intensity signal Lr.

  Note that the G emission intensity sensor 401G and the B emission intensity sensor 401B are replaced with the R filter 410r, the G filter having the maximum transmittance at the peak color of G color, and the B having the maximum transmittance at the peak wavelength of B color. The configuration is the same as that of the R emission intensity sensor 401R described above except that a filter is provided. Further, the R emission intensity sensor 401R, the G emission intensity sensor 401G, and the B emission intensity sensor 401B have, for example, wavelength sensitivity characteristics shown in FIG.

Next, FIG. 5 shows a detailed configuration of the control circuit 600A. The control circuit 600A is divided into three systems of RGB. Since each system is configured similarly, the R system configured by the R peak hold circuit 610r, the AD conversion circuit 620r, the comparison circuit 630r, and the drive signal generation circuit 640r will be described here.
The R peak hold circuit 610r holds the maximum value of the R emission intensity signal Lr and generates the R maximum emission intensity signal Lrp. However, the value of the R maximum emission intensity signal Lrp is reset by the reset signal RESr.

  FIG. 6 shows a detailed configuration of the R peak hold circuit 610r. The final-stage operational amplifier OP2 forms a voltage follower and outputs the voltage at the positive input terminal with a gain of 1. The operational amplifier OP1, the diodes D1 and D2, and the resistor R1 constitute a peak detection circuit. Furthermore, the resistor R2 and the capacitor C constitute a hold circuit, and the hold voltage is reset to the ground potential by the transistor Tr. In such a configuration, when the R emission intensity signal Lr is supplied, the maximum value is held by the hold circuit. When the reset signal RESr becomes high level, the positive input terminal of the operational amplifier OP2 is grounded, and the voltage held by the hold circuit is reset.

  Returning to FIG. The R maximum emission intensity signal Lrp is converted into a digital signal by the AD conversion circuit 620r and supplied to the comparison circuit 630r as R maximum emission intensity data. The comparison circuit 630r compares the R maximum emission intensity data with the R reference value data stored in the reference value storage circuit 651, and generates an R comparison signal. The reference value storage circuit 651 stores G reference value data and B reference value data in addition to the R reference value data. The R reference value data indicates the target value of the emission intensity of the red LED, the G reference value data indicates the target value of the emission intensity of the green LED, and the B reference value data indicates the target value of the emission intensity of the blue LED.

The drive signal generation circuit 640r generates a binary drive signal Dr. Here, the high level (active level) of the drive signal Dr is adjusted based on the R comparison signal so that the value of the maximum red light emission intensity matches or approaches the target value of the light emission intensity. Further, the drive signal generation circuit 640r refers to the R drive condition data supplied from the drive condition storage circuit 652, and determines the duty ratio of the drive signal Dr. Here, the R drive condition data specifies the duty ratio of the drive signal Dr. The R drive condition data is stored in the drive condition storage circuit 652 in association with the temperature. When the temperature data Tp indicating the temperature is supplied, the driving condition storage circuit 652 outputs R driving condition data associated with the temperature.
The drive condition storage circuit 652 stores the G drive condition data and the B drive condition data in association with the temperature in addition to the R drive condition data. The G drive condition data specifies the duty ratio of the drive signal Dg, and the B drive condition data specifies the duty ratio of the drive signal Db.

In the above configuration, one cycle of the drive signals Dr, Dg, and Db is preferably set to one frame cycle or less from the viewpoint of preventing flicker. The timing generation circuit 660 supplies reset signals RESr, RESg, and RESb at a predetermined timing. In this case, when one cycle of the drive signals Dr, Dg, and Db elapses after the reset signals RESr, RESg, and RESb are supplied, the maximum emission intensity signals Lrp output from the peak hold circuits 610r, 610g, and 610b, The levels of Lgp and Lbp are stable as shown in FIG. In this embodiment, the pulse widths of the drive signals Dr, Dg, and Db fluctuate. However, since there is a peak hold circuit, it is not necessary to sample the emission intensity signal, so that troublesome sampling timing control is not necessary. Further, since the peak hold circuit acts as an integrator, an averaged output with less noise can be obtained by the filter effect. As described above, even if a specific sample timing is not specified, it is sufficient to measure only during the light emission period, so a simple control circuit can be used and the cost can be reduced. In addition, since it is resistant to noise, it can measure with high accuracy and improve reliability.
The drive signal generation circuits 640r, 640g, and 640b supply the reset signals RESr, RESg, and RESb, and then drive signals Dr based on the comparison data after one cycle of the drive signals Dr, Dg, and Db has elapsed. , Dg, and Db are preferably produced. In this case, there is no problem even if the timing for generating the reset signals RESr, RESg, and RESb is set asynchronously with the frame period.

  In particular, when driving in a field sequential manner as shown in FIG. 8A, or during a period of one frame as shown in FIG. 8B, a period in which the drive signals Dr, Dg, and Db are at a high level is dispersed. Thus, even when the peak value of current consumption is suppressed, complicated timing control can be eliminated.

<2. Second Embodiment>
The liquid crystal display device according to the second embodiment is configured in the same manner as the liquid crystal display device of the first embodiment described above, except that the control circuit 600B is used instead of the control circuit 600A.
FIG. 9 shows the configuration of the control circuit 600B. The control circuit 600B includes a selection circuit 670 at its input stage. The selection circuit 670 sequentially selects one of the R emission intensity signal Lr, the G emission intensity signal Lg, and the B emission intensity signal Lb according to the selection signals SELr, SELg, and SELb supplied from the timing generation circuit 660. And output as the selected emission intensity signal Ls. Note that the selection signals SELr, SELg, and SELb are exclusively active (low level).

  The selection circuit 670 can be configured as shown in FIG. 10, for example. In this example, three selection units Ur, Ug, and Ub are provided to select three signals. The selection unit Ur includes two inverters, a P-channel transistor, and an N-channel transistor. When the selection signal SELr becomes a low level, the P-channel transistor and the N-channel transistor are turned on, and the R emission intensity signal Lr is output as the selection emission intensity signal Ls. The other selection units Ug and Ub are configured in the same manner as the selection unit Ur.

  Returning to FIG. When the selected emission intensity signal Ls is supplied to the peak hold circuit 610, the peak hold circuit 610 holds the maximum value of the selected emission intensity signal Ls and generates the maximum emission intensity signal Lp. The peak hold circuit 610 is configured similarly to the R peak hold circuit 610r shown in FIG. The maximum light emission intensity signal Lp is converted into a digital signal by the AD conversion circuit 620r and supplied to the comparison circuit 630 as maximum light emission intensity data. The comparison circuit 630 compares the maximum light emission intensity data with the reference value data stored in the reference value storage circuit 651 to generate a comparison signal. Here, the reference value storage circuit 651 stores R reference value data, G reference value data, and B reference value data as reference value data as in the first embodiment described above. The reference value storage circuit 651 outputs any one of R reference value data, G reference value data, and B reference value data in accordance with the selection signal supplied from the timing generation circuit 660. That is, the reference value data corresponding to the selection of the light emission intensity signal by the selection circuit 670 is supplied to the comparison circuit 630.

  The drive signal generation circuit 640 generates binary drive signals Dr, Dg, Db. Here, the high level (active level) of the drive signals Dr, Dg, and Db is adjusted based on each comparison signal so that the value of the maximum light emission intensity matches or approaches the target value of the light emission intensity. Further, the drive signal generation circuit 640 refers to the R drive condition data, G drive condition data, and B drive condition data supplied from the drive condition storage circuit 652 to determine the duty ratios of the drive signals Dr, Dg, and Db. These drive condition data are stored in the drive condition storage circuit 652 in association with the temperature. When the temperature data Tp is supplied, each drive condition data associated with the temperature is output. Further, which color the comparison signal supplied from the comparison circuit 630 corresponds to is designated by the selection signal SEL supplied from the timing generation circuit 660.

FIG. 11 is a timing chart showing the operation of the control circuit 600B. As shown in the figure, the level of the maximum light emission intensity signal Lp is reset by the reset signal RES. Therefore, the reset signal RES needs to be active every time the measurement target of the maximum light emission intensity is switched. In this example, the maximum emission intensity of R color is measured until time t1, and measurement of the maximum emission intensity of G color is started from time t2.
In this case, the period of the reset signal RES is preferably longer than the period of the drive signals Dr, Dg, Db. Thus, there is no problem even if the timing for generating the reset signal RES is set asynchronously with the frame period.

  According to the second embodiment, the configuration of the control circuit 600B can be simplified. Further, although the pulse widths of the drive signals Dr, Dg, and Db vary, there is no need to sample the emission intensity signal because there is a peak hold circuit, so that troublesome sampling timing control becomes unnecessary. Further, since the peak hold circuit acts as an integrator, an averaged output with less noise can be obtained by the filter effect. As described above, even if a specific sample timing is not specified, it is sufficient to measure only during the light emission period, so a simple control circuit can be used and the cost can be reduced. In addition, since it is resistant to noise, it can measure with high accuracy and improve reliability.

  Note that the selection circuit 670 may be arranged after the peak hold circuits 610r, 610g, and 610b shown in FIG. 5, after the AD conversion circuits 610r, 610g, and 610b, or after the comparison circuits 630r, 630g, and 630b.

<3. Electronic equipment>
Next, an electronic apparatus to which the electro-optical device 1 according to the above-described embodiments and application examples is applied will be described. FIG. 12 shows a configuration of a mobile personal computer to which the illumination device according to this embodiment is applied. The personal computer 2000 includes the electro-optical device 1 as a display unit and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002. In the electro-optical device 1, the configuration of the data line driving circuit 200 is simplified, so that a high-definition image can be displayed at a narrow pitch.
FIG. 13 shows a configuration of a mobile phone to which the illumination device according to this embodiment is applied. A cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the electro-optical device 1 as a display unit. By operating the scroll button 3002, the screen displayed on the electro-optical device 1 is scrolled.
FIG. 14 shows a configuration of a portable information terminal (PDA: Personal Digital Assistant) to which the illumination device according to the present embodiment is applied. The information portable terminal 4000 includes a plurality of operation buttons 3001, a power switch 4002, and the electro-optical device 1 as a display unit. When the power switch 4002 is operated, various types of information such as an address book and a schedule book are displayed on the electro-optical device 1.
The electronic apparatus to which the electro-optical device 1 is applied includes a projector, a digital still camera, a liquid crystal television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, as well as those shown in FIGS. Examples include pagers, electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, and devices equipped with touch panels. The electro-optical device 1 described above can be applied as a display unit of these various electronic devices.
The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. A liquid crystal display device using this is also included in the technical scope of the present invention.

It is the schematic diagram which showed the basic composition of the liquid crystal display device which concerns on 1st Embodiment typically. It is sectional drawing cut | disconnected by the plane of Z-Z 'in FIG. 3 is a block diagram illustrating a detailed configuration of a light emission intensity sensor 401. FIG. It is a graph which shows the wavelength sensitivity characteristic of a luminescence intensity sensor. 2 is a block diagram showing a detailed configuration of a control circuit 600A according to the same embodiment. FIG. It is a circuit diagram which shows the detailed structure of R peak hold circuit 610r. It is a timing chart which shows operation | movement of 600 A of control circuits. (A) is a field sequential drive, (b) is explanatory drawing which shows the example of a normal drive. It is a block diagram which shows the detailed structure of the control circuit 600B which concerns on 2nd Embodiment. 5 is a circuit diagram showing a detailed configuration of a selection circuit 670. FIG. It is a timing chart which shows operation of control circuit 600B. 1 is a perspective view illustrating a configuration of a mobile personal computer to which a light emitting device according to an embodiment is applied. It is the perspective view which showed the structure of the mobile telephone to which the light-emitting device which concerns on this embodiment was applied. It is the perspective view which showed the structure of the information portable terminal to which the light-emitting device which concerns on this embodiment was applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, AA ... Liquid crystal panel, 300 ... Back light, 400 ... Back light module, 401 ... Light emission intensity sensor, 500 ... Light emission module, 501 ... Temperature measurement sensor, 550 ... Drive Circuit, 600A, 600B ... Control circuit.

Claims (6)

A plurality of types of light emitting elements each emitting different colors;
Driving means for driving each of the plurality of types of light emitting elements;
A plurality of emission intensity detecting means for measuring emission intensity of each of the plurality of types of light emitting elements and generating a plurality of emission intensity signals;
A plurality of peak hold means for holding a maximum value for each of the plurality of light emission intensity signals and outputting each maximum light emission intensity signal for each of the plurality of types of light emitting elements;
The value of each maximum light emission intensity signal is compared with each reference value determined for each of the plurality of types of light emitting elements, and the value of each maximum light emission intensity signal matches the reference value based on the comparison result. Control means for controlling the drive means,
A light emitting device characterized by that. A plurality of types of light emitting elements each emitting different colors;
Driving means for driving each of the plurality of types of light emitting elements;
A plurality of emission intensity detecting means for measuring emission intensity of each of the plurality of types of light emitting elements and generating a plurality of emission intensity signals;
Selecting means for sequentially selecting one of the plurality of emission intensity signals and outputting a selected emission intensity signal;
Peak hold means for holding a maximum value of the selected light intensity signal and outputting a maximum emission intensity signal;
Select a reference value corresponding to the maximum emission intensity signal from a plurality of reference values determined for each of the plurality of types of light emitting elements, compare the maximum emission intensity signal with the selected reference value, and compare Control means for controlling the drive means so that the value of the maximum emission intensity signal matches the reference value based on the result,
A light emitting device characterized by that.   3. The light-emitting device according to claim 1, wherein each of the plurality of emission intensity detection units has a wavelength sensitivity characteristic corresponding to a peak wavelength of light emitted from the plurality of types of light-emitting elements.   An electronic apparatus comprising the light-emitting device according to claim 1 as a light source. In a method for controlling a light emitting device including a plurality of types of light emitting elements each emitting light of a different color,
A plurality of emission intensity signals are generated by measuring the emission intensity of each of the plurality of types of light emitting elements,
Holding a maximum value for each of the plurality of light emission intensity signals, and generating each maximum light emission intensity signal for each of the plurality of types of light emitting elements,
The value of each maximum light emission intensity signal is compared with each reference value determined for each of the plurality of types of light emitting elements, and the value of each maximum light emission intensity signal matches the reference value based on the comparison result. Driving each of the plurality of types of light emitting elements,
And a method of controlling the light emitting device. In a method for controlling a light emitting device including a plurality of types of light emitting elements each emitting light of a different color,
A plurality of emission intensity signals are generated by measuring the emission intensity of each of the plurality of types of light emitting elements,
Select one of the plurality of emission intensity signals sequentially to generate a selected emission intensity signal,
Holding the maximum value of the selected light intensity signal to generate a maximum emission intensity signal;
Select a reference value corresponding to the maximum emission intensity signal from a plurality of reference values determined for each of the plurality of types of light emitting elements,
Comparing the maximum light emission intensity signal with the selected reference value, and driving each of the plurality of types of light emitting elements so that the value of the maximum light emission intensity signal matches the reference value based on the comparison result.
And a method of controlling the light emitting device.

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