JP2001027889A - Picture display device and picture display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a picture display device which dynamically light-controls the brightness of a light source in accordance with an input video signal by using the vicinity of the range of characteristics at which the luminous efficiency of the light source becomes maximum. SOLUTION: A feature detecting part 1 detects the average luminance level APL of an input video signal. A light-control control part 2 calculates light- control control data controlling a light source 7 based on the difference between a predetermined reference luminance level and the APL. A light-control control signal calculating part 3 inputs the light-control control data outputted by the control part 2 and generates new light-control control data controlling the value of the current (i) of the lamp tube of the light source 7 with respect to only a component changing in a predetermined period among the inputted data based on reference light-control control data giving the current (i0) of the lamp tube with which the luminous efficiency of the light source becomes maximum and outputs the new light-control control data to a light source control part 5. The part 5 dynamically light controllingly controls the brightness of the light source 7 by controlling the value of the current (i) of the lamp tube of the light source 7 according to the new light-control control data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device and an image display method, and more particularly, to a device for displaying an image on a light receiving type light modulating means, wherein the brightness of a light source is changed in accordance with an input video signal. The present invention relates to an image display apparatus and a method for improving the luminous efficiency of a light source when dynamically adjusting (light amount).

[0002]

2. Description of the Related Art As is well known, devices for displaying an image using a liquid crystal panel as a light receiving type light modulating means (hereinafter, referred to as a liquid crystal display device) are widely used as a screen display device of a television receiver or a computer device. Have been. Since this liquid crystal display device is of a non-light-emitting type, a light source is generally provided to increase the visual brightness of a display screen by irradiating light from the back of the liquid crystal panel to make it easy to see an image displayed on the liquid crystal panel.

[0003] Basically, the level of the light source is fixedly set to a content that is manually adjusted by the user. However, in recent years, various methods for dynamically adjusting the brightness of a light source according to an input video signal that changes from time to time (hereinafter, referred to as dimming) have been proposed in order to make images easier to see.

As a conventional method of dimming the brightness of the light source, there is a method disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 8-201812 “Liquid crystal display device”. The conventional dimming method disclosed in this publication detects an average luminance level (APL) of an input video signal and darkens the light source when the average luminance level is higher than a predetermined reference luminance level, and darkens the light source when the average luminance level is lower than a predetermined reference luminance level. Is intended to always obtain a constant display luminance.

[0005]

By the way, the light source includes:
Fluorescent lamps are mainly used in terms of luminous efficiency and the like.
The general characteristics of this fluorescent lamp will be briefly described with reference to FIGS. FIG. 14 is a diagram illustrating an example of a lamp temperature-luminous efficiency characteristic of a general fluorescent lamp. FIG. 15 is a diagram showing an example of a lamp tube current-lamp temperature characteristic of a general fluorescent lamp. In addition, FIG.
In the case where the fluorescent lamp is used as a back lamp, the lamp temperature is 65 ° C. at the current i ₀ . FIG. 16 is a diagram showing an example of a lamp tube current-luminance characteristic of a general fluorescent lamp.

First, as shown in FIG. 14, a general fluorescent lamp has a temperature (65 ° C. in FIG. 14) at which the luminous efficiency becomes maximum due to the mercury vapor pressure inside the lamp tube. Next, as shown in FIG. 15, a general fluorescent lamp has a relationship in which the lamp temperature is proportional to the lamp tube current due to self-heating of the fluorescent lamp. Therefore, from the characteristics of FIGS. 14 and 15, as a result, as shown in FIG. 16, even if the lamp tube current is larger or smaller than the current i ₀ , the luminance adjustment efficiency (luminous efficiency) is reduced.

In view of this, it is attempted to obtain a constant visual luminance (display luminance) by adjusting the brightness of the light source based on the detected average luminance level as disclosed in the above publication. In the conventional dimming method, it is necessary to use the linear portion of the characteristic shown in FIG. 16, so that the light source cannot be used efficiently (that is, the peak luminance cannot be obtained).

[0008] The life of the lamp used for the light source is as follows:
It depends on tube current and temperature. Therefore, in the above-described conventional image display device that dims the brightness of the light source according to the video signal, when the characteristics of the video signal are biased, a large lamp tube current (driving current) is applied to the lamp for a long time. ) And the life of the lamp is shortened.

Therefore, an object of the present invention is to dynamically and optimally adjust the brightness of a light source in accordance with an input video signal by using the vicinity of a characteristic range in which the luminous efficiency of the light source is maximized. It is an object of the present invention to provide an image display device and an image display method. Further, an object of the present invention is to provide an image display device and an image display capable of dynamically and optimally adjusting the brightness of a light source according to an input video signal while maintaining the life of the light source required as a product. Is to provide a way.

[0010]

Means for Solving the Problems and Effects of the Invention A first invention is an image display device for displaying an input video signal on a light receiving type light modulating means having a light source. A feature detecting unit that obtains feature data according to a feature amount of a signal, and a dimming control that inputs the feature data and obtains dimming control data for controlling a light source based on a difference between predetermined reference data and the feature data. Control means, based on reference dimming control data that gives a predetermined drive current at which the light emission efficiency of the light source is maximized, of the dimming control data,
Dimming control signal calculation for generating and outputting new dimming control data for controlling the value of the drive current of the light source so that only the component that changes in a predetermined period converges to the reference dimming control data According to the means and the new dimming control data
Light source control means for dynamically controlling the brightness of the light source by controlling the value of the drive current of the light source;

As described above, according to the first aspect, dimming is performed for a luminance change in a predetermined period in which a temperature change of the light source occurs outside a characteristic range in which the luminous efficiency of the light source is optimal. Control is performed so that the drive current becomes (returns) the drive current given by the reference dimming control data. This allows
The temperature of the light source can always be controlled to an appropriate temperature, and the brightness of the light source can be dynamically adjusted while always maintaining the maximum luminous efficiency, that is, the peak luminance. Therefore, the efficiency in dimming can be improved as compared with the related art.

[0012] A second invention is an invention according to the first invention, wherein the dimming control signal calculating means includes an AC component of the dimming control data which changes within a short time within a predetermined time constant. High-pass filter (hereinafter referred to as HP
F), reference dimming control data, and AC component dimming control data output by the HPF, and adding the both, and outputting new dimming control data.

As described above, according to the second aspect, the first aspect
According to the invention, the drive current for performing light control is based on a predetermined time constant, and the drive current for performing light control is based on the reference light control data. Is controlled to be the driving current given by. Thereby, the temperature of the light source can be constantly controlled to an appropriate temperature, and the brightness of the light source can be dynamically adjusted while the maximum luminous efficiency, that is, the peak luminance is always obtained. Therefore, the efficiency in dimming can be improved as compared with the related art.

According to a third aspect of the present invention, there is provided an image display apparatus for displaying an input video signal on a light receiving type light modulating means having a light source, wherein the video signal is input and feature data corresponding to a feature amount of the video signal is input. A characteristic detecting means to be obtained; a dimming control means for inputting characteristic data; and a dimming control means for obtaining dimming control data for controlling a light source based on a difference between predetermined reference data and the characteristic data. Based on the reference dimming control data and / or the standard dimming control data that gives a predetermined drive current,
Generates new dimming control data for controlling the value of the drive current of the light source so that only the component that changes in a predetermined period converges on the reference dimming control data and / or the standard dimming control data. And a light source control means for dynamically adjusting the brightness of the light source by controlling the value of the drive current of the light source according to the new dimming control data. .

As described above, according to the third aspect of the present invention, dimming is performed for a luminance change in a predetermined period in which a temperature change of the light source occurs outside a characteristic range in which the luminous efficiency of the light source is optimal. Control is performed so that the drive current becomes (returns) the drive current given by either the reference dimming control data or the standard dimming control data. Thereby, the temperature of the light source can be constantly controlled to an appropriate temperature, and the brightness of the light source can be dynamically adjusted while the maximum luminous efficiency, that is, the peak luminance is always obtained. Therefore, the efficiency in dimming can be improved as compared with the related art.

A fourth invention is the invention according to the third invention, wherein the standard dimming control data is dimming control data for providing a drive current set in advance to secure a standard luminance. It is characterized by.

A fifth invention is an invention according to the third invention, wherein the standard dimming control data is dimming control data for giving a predetermined average drive current to secure the lamp life. It is characterized by the following.

As described above, the fourth and fifth aspects of the present invention
FIG. 13 shows typical standard light control data used in the third invention. FIG.

A sixth invention is an invention according to the fourth and fifth inventions, wherein the dimming control signal calculating means inputs the dimming control data, and outputs the standard dimming control data and the reference dimming control data. Control data, and when the dimming control data is equal to or greater than the standard dimming control data, the data difference between the two is set. In this case, only the signal means that outputs a data difference of 0, and only the signal component that changes for a long time equal to or greater than a predetermined time constant among the change difference data output by the slice means is passed. A low-pass filter (hereinafter referred to as LPF), dimming control data, and variable component dimming control data output from the LPF are input, and the variable component dimming control data is subtracted from the dimming control data. And a subtraction means for outputting a new dimming control data.

As described above, according to the sixth aspect, the fourth aspect
In the fifth and fifth aspects of the present invention, based on a predetermined time constant using two of the standard dimming control data and the reference dimming control data, for a luminance change equal to or greater than the standard dimming control data,
The drive current for dimming should be set to the drive current given by the standard dimming control data, and for brightness changes below the reference dimming control data, the drive current for dimming would be set to the drive current given by the reference dimming control data. Control. As a result, even when the control reference value must be set to a value equal to or higher than the drive current at which the light emission efficiency of the light source is the maximum, the standard brightness is secured for a change in brightness where the drive current exceeds the standard dimming control data. The brightness can be adjusted dynamically while driving, and when the drive current is lower than the reference dimming control data, the brightness is changed while maintaining the maximum luminous efficiency, that is, the peak brightness. Can be dimmed. Therefore, the efficiency in dimming can be improved as compared with the related art.

A seventh invention is the invention according to the fourth and fifth inventions, wherein the dimming control signal calculating means inputs the dimming control data and the standard dimming control data, When the dimming control data is equal to or larger than the standard dimming control data, the data difference between the two is output. Otherwise, the slice means for outputting a data difference 0, and the change difference data output from the slice means. LP that passes only signal components that change over a long period of time equal to or greater than a predetermined time constant
F, dimming control data, and variable component dimming control data output from the LPF, and subtraction for outputting new dimming control data obtained by subtracting the variable component dimming control data from the dimming control data. Means.

As described above, according to the seventh aspect, the fourth aspect
In the fifth and fifth aspects of the present invention, the standard dimming control data is used to provide a drive current for performing dimming for a luminance change equal to or greater than the standard dimming control data based on a predetermined time constant. Control is performed so that the driving current is obtained. As a result, even when the control reference value must be set to a value equal to or higher than the drive current at which the light emission efficiency of the light source is the maximum, the standard brightness is secured for a change in brightness where the drive current exceeds the standard dimming control data. The brightness can be dynamically adjusted while the brightness is low. Therefore, the efficiency in dimming can be improved as compared with the related art.

An eighth invention is an invention according to the second, sixth and seventh inventions, wherein the time constant does not satisfy the response of the temperature change of the light source to the increase or decrease of the drive current of the light source. It is characterized in that it is set to less than the time.

As described above, according to the eighth aspect, in the second, sixth, and seventh aspects, the temperature of the light source is always near the characteristic range (appropriate temperature) at which the maximum luminous efficiency is obtained. Can be controlled.

The ninth invention is a invention according to the first to eighth inventions, wherein the sensor means for detecting a physical quantity near the light source, and the luminous efficiency of the light source is always maximized according to the result detected by the sensor means. And a reference dimming control data calculating means for dynamically changing the value of the reference dimming control data to be provided to the dimming control signal calculating means.

As described above, according to the ninth aspect, the first aspect
In the eighth to eighth aspects, sensor means is provided near the light source, and reference dimming control data for providing a drive current that maximizes the light emission efficiency of the light source is obtained in accordance with the detection result of the sensor means. As a result, without being affected by the ambient temperature used,
Brightness can be dynamically adjusted in a state where the luminous efficiency of the light source is always maximum, that is, the peak luminance is obtained.

A tenth aspect of the present invention is the invention according to the first to eighth aspects, wherein a timer means for measuring an elapsed time from the time of power-on, and a light source is always turned on in accordance with the elapsed time counted by the timer means. A reference dimming control data calculating means for dynamically changing a value of the reference dimming control data to be given to the dimming control signal calculating means so that the luminous efficiency is maximized.

As described above, according to the tenth aspect, in the first to eighth aspects, the drive current at which the luminous efficiency of the light source is dynamically maximized sequentially with the lapse of time from when the power is turned on. The reference dimming control data that gives This allows
Even during the transition period from power-on to stable operation,
Brightness can be dynamically adjusted in a state where the luminous efficiency of the light source is always maximum, that is, the peak luminance is obtained.

An eleventh invention is an image display method for displaying an input video signal on a light receiving type light modulating means having a light source, wherein the step of obtaining characteristic data corresponding to the characteristic amount of the video signal is performed on the video signal. And obtaining dimming control data for controlling the light source based on a difference between the predetermined reference data and the characteristic data; and a reference dimming control for giving a predetermined driving current that maximizes the luminous efficiency of the light source. Based on the data, a new dimming control that controls the value of the drive current of the light source so that only the component that changes in a predetermined period in the dimming control data converges on the reference dimming control data. Generating and outputting data; and dynamically controlling the brightness of the light source by controlling the value of the drive current of the light source according to the new dimming control data.

As described above, according to the eleventh aspect, dimming is performed for a luminance change in a predetermined period in which a temperature change of the light source occurs such that the light emission efficiency of the light source is out of the characteristic range in which the light emission efficiency is optimal. Control is performed so that the drive current becomes (returns) the drive current given by the reference dimming control data. This allows
The temperature of the light source can always be controlled to an appropriate temperature, and the brightness of the light source can be dynamically adjusted while always maintaining the maximum luminous efficiency, that is, the peak luminance. Therefore, the efficiency in dimming can be improved as compared with the related art.

A twelfth invention is a invention according to the eleventh invention, wherein the step of generating and outputting comprises, among the dimming control data, an AC component which changes within a short time within a predetermined time constant. And outputting new dimming control data obtained by adding the reference dimming control data and the AC component dimming control data from which only the AC component is extracted.

As described above, according to the twelfth aspect, in the eleventh aspect, the change in luminance at which the temperature of the light source changes so as to be out of the characteristic range in which the luminous efficiency of the light source is optimal is predetermined. Based on the time constant, control is performed such that the drive current for performing light control becomes the drive current provided by the reference light control data. Thereby, the temperature of the light source can be constantly controlled to an appropriate temperature, and the brightness of the light source can be dynamically adjusted while the maximum luminous efficiency, that is, the peak luminance is always obtained. Therefore, the efficiency in dimming can be improved as compared with the related art.

According to a thirteenth aspect, there is provided an image display method for displaying an input video signal on a light receiving type light modulating means having a light source, wherein a step of obtaining characteristic data corresponding to a characteristic amount of the video signal with respect to the video signal. And obtaining dimming control data for controlling the light source based on a difference between the predetermined reference data and the characteristic data; and a reference dimming control for giving a predetermined driving current that maximizes the luminous efficiency of the light source. Based on the data and / or the standard dimming control data, only the components that change during a predetermined period out of the dimming control data converge on the reference dimming control data and / or the standard dimming control data. Generating and outputting new dimming control data for controlling the value of the driving current of the light source so as to control the value of the driving current of the light source according to the new dimming control data. Doing, and a step of dynamically dimming control the brightness of the light source.

As described above, according to the thirteenth aspect, dimming is performed for a luminance change in a predetermined period in which a temperature change of the light source occurs outside a characteristic range in which the luminous efficiency of the light source is optimal. Control is performed so that the drive current becomes (returns) the drive current given by either the reference dimming control data or the standard dimming control data. Thereby, the temperature of the light source can be constantly controlled to an appropriate temperature, and the brightness of the light source can be dynamically adjusted while the maximum luminous efficiency, that is, the peak luminance is always obtained. Therefore, the efficiency in dimming can be improved as compared with the related art.

A fourteenth invention is the invention according to the thirteenth invention, wherein the standard dimming control data is dimming control data for providing a drive current set in advance to secure a standard luminance. It is characterized by.

A fifteenth invention is an invention according to the thirteenth invention, wherein the standard dimming control data is dimming control data for giving a predetermined average drive current to secure the lamp life. It is characterized by the following.

As described above, the fourteenth and fifteenth inventions show typical standard dimming control data used in the thirteenth invention.

A sixteenth invention is a invention according to the fourteenth and fifteenth inventions, wherein the step of generating and outputting includes inputting dimming control data, standard dimming control data and reference dimming data. Control data, and when the dimming control data is equal to or greater than the standard dimming control data, the data difference between the two is set. Of the change difference data output by the step of outputting the data difference 0 and the step of outputting the difference otherwise, only the signal component that changes for a long time equal to or longer than the predetermined time constant. Extracting, and inputting the dimming control data and the changing component dimming control data from which only the changing signal component is extracted, and subtracting the changing component dimming control data from the dimming control data. And outputting the shelf dimming control data.

As described above, according to the sixteenth aspect, in the fourteenth aspect and the fifteenth aspect, based on a predetermined time constant, two types of the standard dimming control data and the reference dimming control data are used. For a luminance change equal to or greater than the standard dimming control data, the driving current for dimming is equal to the driving current given by the standard dimming control data. Control is performed so that the driving current is given by the reference dimming control data. As a result, even when the control reference value must be set to a value equal to or higher than the drive current at which the light emission efficiency of the light source is the maximum, the standard brightness is secured for a change in brightness where the drive current exceeds the standard dimming control data. The brightness can be adjusted dynamically while driving, and when the drive current is lower than the reference dimming control data, the brightness is changed while maintaining the maximum luminous efficiency, that is, the peak brightness. Can be dimmed. Therefore, the efficiency in dimming can be improved as compared with the related art.

A seventeenth invention is a invention according to the fourteenth and fifteenth inventions, wherein the step of generating and outputting includes inputting dimming control data and inputting standard dimming control data, If the dimming control data is equal to or greater than the standard dimming control data, the data difference between the two is output. Otherwise, the data difference 0 is output. Of which
Extracting only a signal component that changes over a long period of time equal to or greater than a predetermined time constant; and inputting dimming control data and changing component dimming control data from which only the changing signal component is extracted. Outputting new dimming control data obtained by subtracting the change component dimming control data from the control data.

As described above, according to the seventeenth aspect, in the fourteenth aspect and the fifteenth aspect, the standard dimming control data is used, and based on a predetermined time constant, a luminance equal to or higher than the standard dimming control data is obtained. With respect to the change, control is performed so that the drive current for performing light control becomes the drive current given by the standard light control data. As a result, even when the control reference value must be set to a value equal to or higher than the drive current at which the light emission efficiency of the light source is the maximum, the standard brightness is secured for a change in brightness where the drive current exceeds the standard dimming control data. The brightness can be dynamically adjusted while the brightness is low. Therefore, the efficiency in dimming can be improved as compared with the related art.

An eighteenth invention is an invention according to the twelfth, sixteenth, and seventeenth inventions, wherein the time constant does not satisfy the response of a change in temperature of the light source to an increase or decrease in the drive current of the light source. It is characterized in that it is set to less than the time.

As described above, according to the eighteenth aspect, in the twelfth, sixteenth, and seventeenth aspects, the temperature of the light source is always near the characteristic range in which the maximum luminous efficiency is obtained (appropriate temperature).
Can be controlled.

A nineteenth invention is a invention according to the eleventh to eighteenth inventions, wherein a step of detecting a physical quantity in the vicinity of the light source, and a step of detecting the physical quantity,
Dynamically changing the value of the reference dimming control data given to the step of generating and outputting new dimming control data so that the luminous efficiency of the light source is always maximized.

As described above, according to the nineteenth aspect, in the eleventh to eighteenth aspects, a physical quantity near the light source is detected, and a drive current that maximizes the luminous efficiency of the light source is given according to the detection result. Obtain reference dimming control data. Thereby, the brightness can be dynamically adjusted while the light emission efficiency of the light source is always maximized, that is, the peak brightness is maintained without being affected by the ambient temperature used.

The twentieth invention is an invention according to the eleventh to eighteenth inventions, wherein the step of measuring the elapsed time from the time of turning on the power and the step of measuring the time are always performed according to the elapsed time counted by the light source. To maximize the luminous efficiency,
Dynamically changing the value of the reference dimming control data given to the step of generating and outputting new dimming control data.

As described above, according to the twentieth aspect, in the eleventh to eighteenth aspects, the drive current at which the luminous efficiency of the light source is dynamically maximized sequentially with the lapse of time from when the power is turned on. The reference dimming control data that gives Thus, even during a transitional period from when the power is turned on to when the operation is stabilized, the light emission efficiency of the light source can always be maximized, that is, the brightness can be dynamically adjusted while maintaining the peak luminance.

[0048]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a block diagram showing a configuration of an image display device according to a first embodiment of the present invention. In FIG. 1, an image display device according to a first embodiment of the present invention includes a feature detecting unit 1, a dimming control unit 2, a dimming control signal calculating unit 3, a light source control unit 5, a light receiving type light And a liquid crystal panel 6 as a modulating means.

Hereinafter, each configuration and operation (image display method) of the image display apparatus according to the first embodiment of the present invention will be described with reference to FIG.
This will be further described with reference to FIGS. A video signal output from a signal processing circuit (not shown) such as a television receiver or a computer device is input to the feature detector 1 and the liquid crystal panel 6, respectively. The liquid crystal panel 6 has a light source 7 which is a fluorescent lamp, and uses the light emitted from the light source 7 to display an input video signal in an easily viewable image.

The feature detecting section 1 detects an average luminance level (hereinafter, referred to as APL) of an input video signal. In addition,
The detection of the APL is a conventionally performed process, and a detailed description thereof will be omitted.

The dimming control section 2 receives the APL detected by the feature detecting section 1 and obtains dimming control data for controlling the light source 7 based on a difference between a predetermined reference luminance level and the APL. The predetermined reference luminance level is particularly the light source 7
Need not be performed, that is, the brightness level at which the lamp tube current i becomes the current i ₀ . Note that the current i ₀ is
As described in the above related art, the current value is a value at which the luminous efficiency of the light source 7 is maximized. Accordingly, the dimming control unit 2 sets the lamp tube current i of the light source 7 to the current i when the APL is lower than the reference luminance level based on the predetermined dimming control amount.
_When the APL is higher than the reference luminance level so as to be larger than ₀ , the dimming control data is obtained such that the lamp tube current i of the light source 7 becomes smaller than the current i0. FIG. 3 shows an example of the waveform of the dimming control data obtained by the dimming control unit 2. Note that the reference luminance level is the lamp tube current i described above.
Is not limited to the luminance level at which the current becomes i ₀ ,
The brightness level lamp tube current i becomes the current i ₀ or more be used as a reference luminance level, it is possible to achieve the same effect. This will be described in a second embodiment below.

The dimming control signal calculating section 3 receives the dimming control data output from the dimming control section 2 and outputs a predetermined lamp tube current i ₀ which maximizes the luminous efficiency of the separately provided light source 7. Based on the given reference dimming control data, only the components that change in a predetermined
, And generates and outputs new dimming control data for controlling the value of the lamp tube current i. FIG. 2 is a block diagram showing an example of a detailed configuration of the dimming control signal calculation unit 3 of FIG. FIG.
, The dimming control signal calculation unit 3 includes a high-pass filter (hereinafter, referred to as HPF) 31 and an addition unit 32. Hereinafter, an example of a specific process of the dimming control signal calculation unit 3 will be described with further reference to FIG.

The HPF 31 is a high-pass filter having a time constant τ that has been generally used in the past, and changes within a short time within the time constant τ in the dimming control data output from the dimming control unit 2. Pass only the AC component. The time constant τ is determined depending on the response of the lamp temperature rise / fall to the increase / decrease of the lamp tube current i of the light source 7 (described later). For example, if the time constant τ is set to 10 seconds, only the dimming control data that changes within 10 seconds
Pass through 31. FIG. 4 shows a waveform of the AC component light control data after the light control data shown in FIG. FIG. 5 shows an example of a more detailed configuration of the HPF 31. FIG. 5A shows a digital circuit with H
FIG. 5B is an example in which the PF 31 is configured, and FIG. 5B is an example in which the HPF 31 is configured by an analog circuit. Since these circuits are conventionally used circuits, detailed description thereof is omitted here.

The adder 32 determines that the luminous efficiency of the light source 7 is maximum.
A predetermined lamp tube current i ₀Give reference dimming
Control data and AC component dimming control output by HPF 31
Input data, add both, and output. Therefore,
Lamp tube current i₀Is set in the HPF 31 as the control reference value.
Brightness change occurring within a short time within the specified time constant τ
The lamp tube current i following the change
Dimming the source 7 and changing the luminance that occurs in the time exceeding the time constant τ
For lightening, the dimming of the light source 7 is controlled by a lamp which is a control reference value.
Tube current i₀Can generate dimming control data back to
(FIG. 4).

Here, the time constant τ of the HPF 31 is
Is set so that there is little change in the rise / fall of the lamp temperature with respect to the increase / decrease of the lamp tube current i, that is, the time during which the response of the temperature change is not satisfied (bad). As a result, for a short-time luminance change in which the change in the lamp temperature cannot catch up, the lamp tube current i can be directly changed and reflected in dimming. Is
The lamp tube current i is returned to the control reference value current i ₀ for the time exceeding the time constant τ, and the lamp temperature is controlled so as to be always in the vicinity of the characteristic range (appropriate temperature) where the maximum luminous efficiency can be obtained. Can be. Therefore, the light source 7 always keeps the maximum luminous efficiency, that is, the peak luminance.
Brightness can be dynamically adjusted. FIG. 6 is a diagram showing an example of a lamp tube current-luminance characteristic of a general fluorescent lamp of the image display device according to the first embodiment of the present invention. In FIG. 6, the solid line indicates the characteristic of the image display device according to the present embodiment, and the dashed line indicates the characteristic of the conventional image display device (liquid crystal display device) shown in FIG.

Then, the light source control unit 5 controls the light source 7 according to the new dimming control data output from the dimming control signal calculating unit 3 (after addition in the example shown in FIG. 2, output from the adding unit 32). The brightness of the light source 7 is dynamically controlled by controlling the value of the lamp tube current i.

As described above, according to the image display apparatus and the method according to the first embodiment of the present invention, the luminance change at which the lamp temperature changes such that the light emission efficiency of the light source 7 is out of the optimum characteristic range is obtained. Controls the lamp tube current i for performing dimming based on a predetermined time constant τ to become (return) a current i ₀ which is a control reference value. As a result, the lamp temperature can always be controlled to an appropriate temperature, and always the maximum luminous efficiency, that is, while maintaining the peak luminance,
The brightness of the light source 7 can be dynamically adjusted. Therefore, the efficiency in dimming can be improved as compared with the related art.

In the first embodiment, the lamp tube current i for dimming becomes the current i ₀ even for a specific luminance change where the lamp tube current i is equal to or less than the current i ₀ which is the control reference value. It was described to control as follows. However, if the above control is performed even when the user dares to desire a dark screen as a whole (for example, when light adjustment (contrast adjustment or the like) is performed manually), the black level is raised as a whole and the darkness rises. The screen cannot be obtained. For this reason, when the user desires a dark screen as a whole, control is not performed for a specific luminance change in which the lamp tube current i is equal to or less than the current i _0, or the current i which is a control reference value is not controlled. Set the _value to ₀ and lower it to set the lamp tube current i
May be controlled to be a current value lower than the current i ₀ .

Further, in the first embodiment, the reference dimming control data is the dimming control data for giving the lamp tube current at which the luminous efficiency of the light source is maximized. It may be dimming control data that gives the optimum lamp tube current determined by the control.

(Second Embodiment) In the first embodiment, the current i _{0 at} which the luminous efficiency of the light source 7 becomes maximum is used as a control reference value, and the lamp tube current i
Has been described to be controlled to the control reference value. However, in actually commercializing the image display device, it is conceivable that the temperature of the light source 7 rises due to self-radiation of the light source 7 and radiation from circuit elements and the like inside the device. For this reason, the current i _{0 at} which the luminous efficiency is maximized changes substantially to a low value as the temperature of the light source 7 rises, and it is necessary to secure the luminance required as a product (hereinafter referred to as standard luminance). In some cases, the control reference value must be set to the current i ₀ or more.

In this case, a current value set as a control reference value (hereinafter, referred to as a current i
_{For the} above lamp tube current i, the control described in the first embodiment is performed to dynamically and efficiently dimming the brightness while securing the required standard brightness. The effect can be achieved. However, if the control described in the first embodiment is performed on the lamp tube current i equal to or less than the current i _STD , the efficiency is rather lowered (the luminous efficiency is reduced for all specific luminance changes). This is because the lamp tube current i is controlled so that the current i _STD becomes higher than the maximum current i ₀ ). Therefore,
The second embodiment provides an image display device that can dynamically and efficiently adjust light even in the above-described case.

FIG. 7 is a block diagram showing the configuration of the image display device according to the second embodiment of the present invention. In FIG. 7, the image display device according to the second embodiment of the present invention includes a feature detecting unit 1, a dimming control unit 2, and a dimming control signal calculating unit 4.
, A light source control unit 5 and a liquid crystal panel 6. Also,
The liquid crystal panel 6 has a light source 7 which is a fluorescent lamp.

As shown in FIG. 7, in the image display device according to the second embodiment, the dimming control signal operation unit 3 of the image display device according to the first embodiment is replaced with the dimming control signal operation unit 4. This is a configuration in which Since other configurations of the image display device according to the second embodiment are the same as the configurations of the image display device according to the first embodiment, the same reference numerals are given to the other configurations. The description is omitted.
Hereinafter, each configuration and operation (image display method) of the image display device according to the second embodiment of the present invention will be described with reference to FIGS. Will be further described.

FIG. 8 is a block diagram showing an example of a detailed configuration of the dimming control signal calculation section 4 of FIG. In FIG.
The dimming control signal calculation unit 4 includes a slicer 41, a low-pass filter (hereinafter, referred to as LPF) 42, and a subtraction unit 43.
And The dimming control data output from the dimming control unit 2 is input to the slicer 41 and the subtraction unit 43. The slicer 41 inputs the dimming control data, and as the reference dimming control data, a current i _STD set in advance to secure a required standard luminance and a current i _{0 at} which the light emission efficiency of the light source 7 is maximized. Enter And the slicer 41
Converts the input dimming control data X into change difference data Y and outputs it based on the following equation. Y = X−i _STD (X> i _STD ) Y = 0 (i ₀ ≦ X ≦ i _STD ) Y = X−i ₀ (X <i ₀ ) The input / output characteristics of the slicer 41 are shown in FIG. Show.
For example, when the dimming control data X shown in FIG. 10A is input, the waveform of the change difference data Y output by the slicer 41 becomes the waveform shown in FIG.

The LPF 42 is a low-pass filter having a time constant τ which has been generally used in the past. Of the change difference data Y output from the slicer 41, a signal component (eg, a time-varying signal longer than the time constant τ) that changes over a long period of time is used. (AC component and DC component). The time constant τ is determined depending on the responsiveness of the increase / decrease of the lamp temperature to the increase / decrease of the lamp tube current i of the light source 7 as in the HPF 31 described in the first embodiment. Therefore, in response to the input of the change difference data Y shown in FIG. 10B, the waveform of the change component dimming control data L output by the LPF 42 is as shown in FIG.
It becomes as shown in.

The subtraction unit 43 receives the dimming control data X and the variable component dimming control data L, and adds new dimming control data Z obtained by subtracting the variable component dimming control data L from the dimming control data X. Output. Therefore, for a luminance change occurring in a short time within the time constant τ set by the LPF 42, the light source 7 is dimmed by increasing or decreasing the lamp tube current i in accordance with the change. When the lamp tube current i is equal to or greater than the current i _{STD with} respect to a luminance change occurring in a time exceeding the time constant τ, the dimming of the light source 7 is controlled to the standard luminance control reference value (upper control reference value). back to the current i _STD is, if the lamp tube current i is the current i ₀ or less, adjustment to return the dimming of the light source 7 to the current i ₀ is the control reference value of the maximum luminous efficiency (lower control reference value) Light control data Z (FIG. 10D) can be generated.

As described above, according to the image display apparatus and method according to the second embodiment of the present invention, the control reference value must be set to be equal to or greater than the current i ₀ at which the light source 7 has the maximum luminous efficiency. In the case where there is no lamp lamp current i based on a predetermined time constant τ, for a specific brightness change equal to or greater than the current i _STD at which the lamp tube current i is the upper control reference value, the lamp tube current i for dimming becomes the current i _STD , For a specific luminance change in which the lamp tube current i is equal to or less than the current i ₀ which is the lower control reference value, the lamp tube current i for dimming is controlled so as to become (return to) the current i ₀ . Accordingly, for a specific luminance change in which the lamp tube current i is equal to or greater than the current i _STD , the brightness can be dynamically adjusted while maintaining the required standard luminance, and the lamp tube current i is equal to or less than the current i _0. With respect to the specific luminance change, the brightness can be dynamically adjusted while maintaining the maximum luminous efficiency, that is, the peak luminance. Therefore, the efficiency in dimming can be improved as compared with the related art.

[0068] Incidentally, in the second embodiment, the lamp tube current i for even specific luminance change in the current i ₀ below a lower control reference value, the lamp tube current i is the current effect dimming i ₀ It has been described that control is performed so that However, if the above control is performed even when the user dares to desire a dark screen as a whole, the black level is raised as a whole and a dark screen cannot be obtained. For this reason, when the user desires a dark screen as a whole, control is not performed for a specific luminance change in which the lamp tube current i is equal to or less than the current i _0, or the current i which is a control reference value is not controlled. _The control may be performed such that the lamp tube current i becomes a reduced current value by decreasing ₀ . In the former case, the slicer 41 may convert the input dimming control data X into change difference data Y based on the following formula and output the converted dimming control data X. Y = X−i _STD (X> i _STD ) Y = 0 (X ≦ i _STD ) In this case, the input / output characteristics of the slicer 41 are shown in FIGS. 11A and 10A. Control data X
Dimming control data Z output by the subtractor 43 in response to the input
11B is shown in FIG.

In the second embodiment, the upper control reference value i _STD is used as the dimming control data for providing the standard brightness. However, the dimming for giving the average lamp tube current determined by the lamp life required as a product. It may be control data.

(Third Embodiment) In the second embodiment, when an image display device is actually commercialized, self-radiation of the light source 7 and heat radiation from circuit elements and the like inside the device are required. , The temperature of the light source 7 may increase. However, another cause of the change in the temperature of the light source 7 is a change in the environmental temperature at which the product is used.
The ambient temperature of the light source 7 changes every time according to the change of the environmental temperature. Therefore, depending on the environmental temperature, the current i ₀ set in advance as the control reference value is:
In some cases, the current value is not the current value at which the luminous efficiency of the light source 7 is maximized. Therefore, the third embodiment provides an image display device that can always adjust the light at the maximum luminous efficiency even in the case described above.

FIG. 12 is a block diagram showing a configuration of an image display device according to the third embodiment of the present invention. 12, the image display device according to the third embodiment of the present invention includes a feature detecting unit 1, a dimming control unit 2, a dimming control signal calculating unit 3 (or 4), and a reference dimming control data. Arithmetic unit 8
, A sensor 9, a light source control unit 5, and a liquid crystal panel 6. The liquid crystal panel 6 includes a light source 7 which is a fluorescent lamp.
have.

As shown in FIG. 12, the image display device according to the third embodiment is different from the image display device according to the first or second embodiment in that a reference dimming control data calculation unit 8 and a sensor 9 are added. The configuration is further added. Note that another configuration of the image display device according to the third embodiment is the same as that of the first embodiment.
Since the configuration is the same as that of the image display device according to the second embodiment, the other components are denoted by the same reference numerals and description thereof is omitted. Hereinafter, each configuration and operation (image display method) of the image display device according to the third embodiment of the present invention will be described focusing on portions different from those of the image display devices according to the first and second embodiments.

The sensor 9 is a general sensor that detects a physical quantity such as temperature or light and outputs the result.
It is installed near. When the sensor 9 is a temperature sensor, the sensor 9 detects the temperature of the installed environment (that is, the temperature in the vicinity of the light source 7) and outputs the detection result to the reference dimming control data calculation unit 8. When the sensor 9 is an optical sensor, the light amount of the light source 7 is detected, and the detection result is output to the reference dimming control data calculation unit 8.

The reference dimming control data calculating section 8 includes a sensor 9
There based on the detection result output, luminous efficiency of the light source 7 is determined lamp tube current i ₀ having the maximum output to the dimming control signal computing unit 3 as the reference light adjustment control data (or 4).
Here, when the detection result is a temperature, the reference dimming control data calculation unit 8 determines the lamp tube current at which the luminous efficiency of the light source 7 becomes maximum according to the lamp tube current-lamp temperature characteristic (see FIG. 15). i ₀ is obtained, and when the detection result is a light amount, the luminous efficiency is calculated based on a ratio between the light amount and the lamp tube current, and the lamp tube current i _{0 at} which the luminous efficiency of the light source 7 is maximized.
Ask for.

As described above, according to the image display device and the method according to the third embodiment of the present invention, the sensor 9 is provided near the light source 7, and the luminous efficiency of the light source 7 is maximized according to the detection result of the sensor 9. Request lamp tube current i ₀ which becomes. Thereby, the brightness can be dynamically adjusted in a state where the light emission efficiency of the light source 7 is always maximum, that is, the peak brightness is maintained without being affected by the environmental temperature used.

(Fourth Embodiment) In addition to the causes described in the third embodiment, the temperature of the light source 7 may be changed due to a change in the temperature during a transitional period from when the power of the product is turned on to when the operation is stabilized. There is a transition. Therefore, the fourth embodiment provides an image display device that can always control light with optimum luminous efficiency even when the power is turned on.

FIG. 13 is a block diagram showing the configuration of the image display device according to the fourth embodiment of the present invention. In FIG. 13, the image display device according to the fourth embodiment of the present invention includes a feature detecting unit 1, a dimming control unit 2, a dimming control signal calculating unit 3 (or 4), and a reference dimming control data. Arithmetic unit 10
, A timer 11, a light source controller 5, and a liquid crystal panel 6. Further, the liquid crystal panel 6 has a light source 7 which is a fluorescent lamp.

As shown in FIG. 13, the image display device according to the fourth embodiment is different from the image display device according to the first or second embodiment in that a reference dimming control data calculation unit 10 and a timer 11 are provided. The configuration is further added. Note that other configurations of the image display device according to the fourth embodiment are the same as the configurations of the image display devices according to the first and second embodiments, and thus the same reference numerals are used for the other configurations. And the description is omitted. Hereinafter, each configuration and operation (image display method) of the image display device according to the fourth embodiment of the present invention will be described focusing on portions different from those of the image display devices according to the first and second embodiments.

The timer 11 measures the elapsed time from when the power of the product is turned on. The reference dimming control data calculation unit 10
The time measured by the timer 11 is obtained, the temperature rise of the light source 7 is predicted with the lapse of time from when the power is turned on, and the lamp tube current i _{0 at} which the luminous efficiency of the light source 7 is maximized is dynamically and sequentially obtained. Dimming control signal calculation section 3 as reference dimming control data
(Or 4). When the power is turned on in a stable operation state (for example, when the power is turned on immediately after using the product), the timer 11 measures the time elapsed since the power was turned off. Sometimes, the control in the reference dimming control data calculation unit 10 may not be performed.

As described above, according to the image display apparatus and method according to the fourth embodiment of the present invention, the luminous efficiency of the light source 7 dynamically and dynamically becomes maximum with the lapse of time from when the power is turned on. Request lamp tube current i ₀ comprising. Thus, even during a transitional period from when the power is turned on to when the operation is stabilized, the light emission efficiency of the light source 7 is always maximized, that is, the brightness can be dynamically adjusted while the peak luminance is still obtained.

The control of the lamp tube current i ₀ described in the fourth embodiment can be arbitrarily combined with the control of the lamp tube current i ₀ described in the third embodiment. .

In the first to fourth embodiments, the case where the light source 7 is a fluorescent lamp has been described as an example. However, the light source 7 can be used for other light sources in the same manner as described above. It is possible.

Further, in the first to fourth embodiments, the case where the dimming control of the light source 7 is performed based on the average luminance level (APL) of the input video signal has been described. The dimming control of the light source 7 may be performed based on the maximum luminance level or the minimum luminance level of the signal, or a combination of these with the average luminance level.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image display device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a detailed configuration of a dimming control signal calculation unit 3 of FIG.

FIG. 3 is a diagram illustrating an example of a waveform of light control data obtained by a light control unit 2 of FIG. 1;

4 is a diagram illustrating a waveform of AC component dimming control data after the dimming control data illustrated in FIG. 3 has passed through an HPF 31. FIG.

FIG. 5 is a block diagram illustrating an example of a more detailed configuration of the HPF 31 of FIG. 2;

FIG. 6 is a diagram showing an example of a lamp tube current-luminance characteristic of a general fluorescent lamp of the image display device according to the first embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of an image display device according to a second embodiment of the present invention.

8 is a block diagram illustrating an example of a detailed configuration of a dimming control signal calculation unit 4 in FIG.

9 is a diagram showing input / output characteristics of the slicer 41 of FIG.

FIG. 10 is a diagram showing an example of a waveform of each dimming control data in each unit of the dimming control signal calculation unit 4 shown in FIG.

11 is a diagram showing other input / output characteristics of the slicer 41 of FIG.

FIG. 12 is a block diagram illustrating a configuration of an image display device according to a third embodiment of the present invention.

FIG. 13 is a block diagram illustrating a configuration of an image display device according to a fourth embodiment of the present invention.

FIG. 14 is a diagram showing an example of a lamp temperature-luminous efficiency characteristic of a general fluorescent lamp.

FIG. 15 is a diagram showing an example of a lamp tube current-lamp temperature characteristic of a general fluorescent lamp.

FIG. 16 is a diagram showing an example of a lamp tube current-luminance characteristic of a general fluorescent lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Feature detection part 2 ... Dimming control part 3,4 ... Dimming control signal calculating part 5 ... Light source controlling part 6 ... Liquid crystal panel 7 ... Light source 8,10 ... Reference dimming control data calculating part 9 ... Sensor 11 ... Timer 31 HPF 32 Adder 41 Slicer 42 LPF 43 Subtractor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshito Ota 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Wataru Machitori 1006 Kazuma Kadoma, Kazuma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. BF38 EA01 FA33 FA54 5C058 AA07 AA08 AB03 BA05 BA29 BB25 EA26 EA51 5C080 AA10 BB05 DD04 EE28 JJ02 JJ04 JJ05 5G435 AA03 AA14 BB12 BB15 EE25 EE30 GG24 LL04 LL08

Claims (20)

[Claims] 1. An image display apparatus for displaying an input video signal on a light receiving type light modulation means having a light source, wherein the video signal is input and feature detection is performed to obtain feature data corresponding to a feature amount of the video signal. Means for inputting the characteristic data, dimming control means for obtaining dimming control data for controlling the light source based on a difference between predetermined reference data and the characteristic data, and the luminous efficiency of the light source is maximized. Based on the reference dimming control data that gives a predetermined driving current, only the component that changes in a predetermined period of the dimming control data converges to the reference dimming control data. Means for generating and outputting new dimming control data for controlling the value of the driving current of the light source; and controlling the value of the driving current of the light source according to the new dimming control data. It is, and a light source control means for dynamically controlling dimming the brightness of the light source, the image display device. 2. The dimming control signal calculating means, comprising: a high-pass signal that passes only a short-time alternating component within a predetermined time constant in the dimming control data.
Adding means for inputting a filter (hereinafter referred to as HPF), the reference dimming control data, and the AC component dimming control data output by the HPF, and outputting the new dimming control data obtained by adding both; The image display device according to claim 1, comprising: 3. An image display apparatus for displaying an input video signal on a light receiving type light modulating means having a light source, wherein the video signal is input, and feature detection for obtaining feature data corresponding to a feature amount of the video signal is performed. Means for inputting the characteristic data, dimming control means for obtaining dimming control data for controlling the light source based on a difference between predetermined reference data and the characteristic data, and the luminous efficiency of the light source is maximized. Based on the reference dimming control data and / or the standard dimming control data that gives a predetermined driving current, only the component that changes in a predetermined period in the dimming control data is referred to as the reference dimming control data. Dimming control signal calculating means for generating and outputting new dimming control data for controlling the value of the drive current of the light source so as to converge to the dimming control data and / or the standard dimming control data; An image display device comprising: a light source control unit that dynamically controls the brightness of the light source by controlling the value of the drive current of the light source according to the new dimming control data. 4. The image display device according to claim 3, wherein the standard light control data is light control data for providing a drive current set in advance to secure a standard luminance. 5. The image display device according to claim 3, wherein the standard dimming control data is dimming control data for giving an average driving current set in advance to secure a lamp life. . 6. The dimming control signal calculating means receives the dimming control data, inputs the standard dimming control data and the reference dimming control data, and sets the dimming control data to the standard dimming control data. If the light control data is equal to or greater than the light control data, the data difference between the two is used.If the light control data is equal to or less than the reference light control data, the data difference between the two is used. A slicing means for outputting, and a low-pass filter (hereinafter, referred to as LPF) for passing only a signal component that changes for a long time equal to or longer than a predetermined time constant among the change difference data output from the slicing means; The new dimming control data obtained by inputting the dimming control data and the variable component dimming control data output from the LPF, and subtracting the variable component dimming control data from the dimming control data. The image display device according to claim 4, further comprising: a subtraction unit that outputs. 7. The dimming control signal calculating means receives the dimming control data and the standard dimming control data, and when the dimming control data is equal to or greater than the standard dimming control data. Is a slicing unit that outputs a data difference between the two, and otherwise a data difference 0, and a signal component that changes for a long time equal to or longer than a predetermined time constant among the change difference data output by the slicing unit. A low-pass filter (hereinafter, referred to as an LPF) that passes only the light, the dimming control data, and the changing component dimming control data output from the LPF, and the changing component is calculated from the dimming control data. The image display device according to claim 4, further comprising a subtraction unit configured to output the new light control data obtained by subtracting the light control data. 8. The method according to claim 2, wherein the time constant is set to be equal to or less than a time during which the responsiveness of a change in temperature of the light source to the increase or decrease in the drive current of the light source is not satisfied. The image display device as described in the above. 9. A sensor means for detecting a physical quantity in the vicinity of the light source, and the reference provided to the dimming control signal calculating means such that the light emission efficiency of the light source is always maximized according to a result detected by the sensor means. Reference dimming control data calculating means for dynamically changing the value of the dimming control data, further comprising:
The image display device according to claim 1. 10. A timer means for measuring an elapsed time from the time of power-on, and the light control control signal calculating means is controlled so that the luminous efficiency of the light source is always maximized in accordance with the elapsed time measured by the timer means. The image display device according to any one of claims 1 to 8, further comprising a reference dimming control data calculating unit that dynamically changes a value of the reference dimming control data to be provided. 11. An image display method for displaying an input video signal on a light receiving type light modulating means having a light source, the method comprising: obtaining characteristic data corresponding to a characteristic amount of the video signal with respect to the video signal; A step of obtaining dimming control data for controlling the light source based on a difference between the determined reference data and the feature data; and a reference dimming control for giving a predetermined driving current for maximizing the luminous efficiency of the light source. Based on the data, only a component of the dimming control data, which changes in a predetermined period, controls the value of the drive current of the light source so as to converge on the reference dimming control data. Generating and outputting light control data; and dynamically controlling the brightness of the light source by controlling the value of the drive current of the light source according to the new light control data. That comprises the steps, the image display method. 12. The method according to claim 12, wherein the step of generating and outputting comprises: extracting, from the dimming control data, only an AC component that changes in a short time within a predetermined time constant; And outputting the new dimming control data obtained by adding the AC component dimming control data from which only the AC component is extracted.
The image display method described in 1. 13. An image display method for displaying an input video signal on a light receiving type light modulating means having a light source, wherein: for the video signal, a step of obtaining feature data corresponding to a feature amount of the video signal; A step of obtaining dimming control data for controlling the light source based on a difference between the determined reference data and the feature data; and a reference dimming control for giving a predetermined driving current for maximizing the luminous efficiency of the light source. Based on the data and / or the standard dimming control data, only the component that changes in a predetermined period of the dimming control data is converted to the reference dimming control data and / or the standard dimming control data. Generating and outputting new dimming control data for controlling the value of the drive current of the light source so as to converge, and according to the new dimming control data, By controlling the value of the drive current source, and a step of controlling dynamically dimming the brightness of the light source, an image display method. 14. The image display method according to claim 13, wherein the standard dimming control data is dimming control data for providing a drive current set in advance to secure a standard luminance. 15. The dimming control data according to claim 13, wherein the standard dimming control data is a dimming control data for giving a predetermined average drive current to secure a lamp life.
The image display method described in 1. 16. The step of generating and outputting comprises inputting the dimming control data, inputting the standard dimming control data and the reference dimming control data, and setting the dimming control data to the standard dimming control data. If the light control data is equal to or greater than the light control data, the data difference between the two is used.If the light control data is equal to or less than the reference light control data, the data difference between the two is used. Outputting, from the change difference data output by the step of outputting the difference, extracting only a signal component that changes over a long period of time equal to or greater than a predetermined time constant; and the dimming control data; And input the variable component dimming control data from which only the signal component to be extracted is extracted, and output the new dimming control data obtained by subtracting the variable component dimming control data from the dimming control data. 16. The image display method according to claim 14, further comprising the steps of: 17. The method of generating and outputting, when the dimming control data is input and the standard dimming control data is input, and the dimming control data is equal to or more than the standard dimming control data. Of the difference data output by the step of outputting the data difference between the two, and the data difference 0 otherwise; and the step of outputting the difference, the data difference changes for a long time equal to or longer than a predetermined time constant. Extracting only the signal component; and inputting the dimming control data and the changing component dimming control data from which only the changing signal component is extracted, and changing the dimming control data from the dimming control data. And outputting the new dimming control data obtained by subtracting the following. 18. The method according to claim 12, wherein the time constant is set to be equal to or less than a time during which the responsiveness of a temperature change of the light source to the increase or decrease of the drive current of the light source is not satisfied.
16. The image display method according to 16 or 17. 19. A step of detecting a physical quantity in the vicinity of the light source, and generating the new dimming control data according to a result detected by the detecting step so that the light emission efficiency of the light source is always maximized. 19. The image display method according to claim 11, further comprising: dynamically changing a value of the reference dimming control data given to the outputting step. 20. A step of measuring an elapsed time from power-on, and the step of measuring the new dimming control data so that the light emission efficiency of the light source is always maximized in accordance with the elapsed time measured by the time counting step. 19. The image display method according to claim 11, further comprising dynamically changing a value of the reference dimming control data to be provided to the step of generating and outputting.