JP2003233363A - Image display device, signal processor and signal processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display video signals and image signals being generated by computer software on a same display section in a natural manner. <P>SOLUTION: A control circuit 13 of an LCD driver IC 11 controls a reference voltage generating section 14 based on the instruction given by a luminance correction switching switch. While analog signals are being generated, a correction is made so that luminance characteristic becomes a γ value for input digital signals having luminance characteristic in which inverse γ correction is applied for a CRT display, for example. On the other hand, a correction is made so that luminance characteristic becomes linear for the input signals having a linear luminance characteristic such as image signals generated by computer software. <P>COPYRIGHT: (C)2003,JPO

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, a signal processing device, and a signal processing method, and, for example, performs correction such that a luminance characteristic becomes a γ value according to an input image signal, or a straight line. The present invention relates to an image display device, a signal processing device, and a signal processing method for performing such correction.

[0002]

2. Description of the Related Art A conventional LCD brightness (equivalent to transmittance) correction will be described. FIG. 2 and FIG. 3 are diagrams showing respective examples of the luminance (equivalent to the transmittance) correction of the LCD. In these figures, the horizontal axis represents the input signal voltage (Vsig) and the vertical axis represents the brightness. A is L
The original signal (transmittance) characteristic of the CD, B indicates the signal correction characteristic necessary for the luminance characteristic for the input signal (input image signal) (Vsig) to become the straight line C, and D indicates the input signal (input image signal) ( The luminance characteristic with respect to Vsig) is about 2.
2 shows the signal correction characteristic necessary to obtain the characteristic E of 2.

Conventionally, when an input signal is displayed on an LCD monitor, an input signal which is inversely γ-corrected on the sending side like a video signal is input in consideration of the transmittance characteristic A peculiar to the LCD. By correcting the brightness of the input signal in the internal circuit of the LCD monitor so that the LCD brightness characteristic with respect to the signal becomes D in FIG. 3, the brightness characteristic of the LCD monitor itself becomes
As shown by E in FIG. 3, the characteristic has a γ value of about 2.2, that is, the characteristic is almost equal to that of the CRT. Therefore, in the LCD monitor, the input video signal can obtain a linear and accurate display characteristic.

However, when the inverse γ correction is not performed and the input signal having the linear luminance characteristic is used, the display characteristic on the LCD monitor becomes E in FIG. This is a serious problem in gradation display and color display. Therefore, for an input signal having a linear luminance characteristic, the transmittance characteristic of the LCD is taken into consideration, and correction is performed so that the luminance characteristic of the LCD becomes B in FIG. 2C
The linear characteristics as shown in (3) are used to obtain a natural image display.

By the way, in the conventional LCD monitor, it is the current situation that the above-mentioned input signal is preset so that either the brightness correction B or D can be performed.

Next, an example of a conventional LCD monitor is shown in FIG. FIG. 4 is a schematic view of a main part showing an example of a brightness correction device in a conventional LCD monitor. In the figure, 1 is L
This is a CD driver IC, and this LCD driver IC1
Are digital signals R, G, as input signals from the outside.
B (in the case of an analog signal, it is converted into a digital signal by an A / D converter in advance) is supplied. LCD
The driver IC 1 latches the input digital signals R, G, B, decodes the input signal by a built-in D / A converter, and supplies the signals to the signal electrodes X _{1 to} X ₁₉₂₀ of the LCD 2. The reference voltage generating unit 3 D / A converter in the LCD driver IC1 is composed of a resistor R ₂₁ to R _2n, by setting the resistance ratio of the resistors R ₂₁ to R _2n, brightness correction characteristic B or Only one side of D is uniquely set. Reference numeral 4 denotes a scan driver IC, which supplies the output (scan signal) of the scan driver IC 4 to the signal electrodes Y _{1 to} Y ₄₈₀ of the LCD 2.

In the conventional LCD monitor having the above-mentioned structure, generally the main purpose is to watch a video signal,
The brightness is corrected so that the transmittance characteristic of the LCD is similar to that of the conventional CRT. That is,
In general, since the video signal is subjected to inverse γ correction on the sending side in accordance with the CRT, the resistors R _{21 to} R _2n of the reference voltage generating unit 3 are set so that the γ value of the brightness characteristic on the LCD side becomes about 2.2.
Resistance ratio is set, and brightness correction D is performed.

[0008]

The LCD of FIG. 4 described above.
In the monitor, generally, the reference voltage generator 3 can perform the brightness correction D shown in FIG. 3 in accordance with the video signal. However, unlike the case of computer software, the brightness correction characteristic is not taken into consideration for an input signal that digitally gradations. Therefore, in this LCD monitor, as in the case of software of a computer, an input signal for digitally gradation becomes unnatural in gradation display and color display. was there.

Further, when the LCD monitor of FIG. 4 is set so as to be able to perform the brightness correction B of FIG. 2 on an input signal having a linear brightness characteristic, the inverse γ-corrected video signal is processed. 3 has the drawback that the brightness correction D of FIG. 3 cannot be performed and a linear display characteristic cannot be obtained.

[0010]

The image display device of the present invention includes a control signal generator for generating a control signal for gamma-correcting the brightness characteristic corresponding to the type of the input image digital signal, and the brightness characteristic. It is possible to generate a plurality of reference voltages for setting, and selectively generate a reference voltage corresponding to the type of the input image digital signal based on the control signal generated by the control signal generator. Of the input image digital signal by using the reference voltage generating section and the reference voltage generated by the reference voltage generating section.
Compensate to generate an analog signal and drive the display D /
And an A converter.

The signal processing apparatus of the present invention comprises a control signal generating section for generating a control signal for γ-correcting the brightness characteristic corresponding to the type of the input image digital signal, and a plurality of control signal generating sections for setting the brightness characteristic. And a reference voltage generator that selectively generates a reference voltage corresponding to the type of the input image digital signal based on the control signal generated by the control signal generator. ,
Using the reference voltage generated by the reference voltage generator,
And a D / A converter for generating an analog signal for driving the display unit by γ-correcting the input image digital signal.

The signal processing method of the present invention generates a control signal for performing γ correction of the luminance characteristic corresponding to the type of the input image digital signal, and based on the control signal, outputs the input image digital signal. Selectively generates a reference voltage to set the brightness characteristics corresponding to the type, and uses the reference voltage to γ-correct the input image digital signal and generate an analog signal to drive the display section. And output.

In the image display device, the signal processing device, and the signal processing method of the present invention, the control signal for generating the gamma correction of the brightness characteristic corresponding to the type of the input image digital signal is generated, and the control signal is generated. A reference voltage corresponding to the type of the input image digital signal is selectively generated based on the above, and the input image digital signal is γ-corrected using the reference voltage to drive the display unit. An analog signal is generated and output.

Therefore, a linear input image signal which has not been subjected to the inverse γ correction like the software of a computer is subjected to LC
When displaying on a D monitor, an image with no discomfort in gradation display and color display can be obtained by performing correction so that the luminance characteristic becomes linear. Therefore, on the LCD monitor, both the video signal and the computer software can be viewed in a natural state.

[0015]

1 is a block diagram of an embodiment of the present invention.
It will be described with reference to FIGS. FIG. 1 shows a liquid crystal according to the present invention.
An example of a brightness correction device in an image display device
FIG. In the figure, the input signal from the outside is
Digital signals R, G, B (for analog signals,
Convert it into a digital signal with an A / D converter.
It ) Is supplied to the LCD driver IC 11. L
The CD driver IC 11 receives the input digital signals R, G, B
Latched and input by built-in D / A converter
The signal signal X of the LCD 12 is decoded by decoding the force signal.₁ ~ X
₁₉₂₀It is designed to supply a signal to. LCD dry
Reference voltage generation of the D / A converter built in the IC11
The raw part 14 has a resistance R₁₁~ R_1nAnd resistance R_{twenty one}~ R_2nAnd switch
Ji SW ₁ ~ SW_n Composed of.

Here, the resistance R₁₁~ R_1nAbout
Curve of the brightness correction characteristic B of FIG. 2 with respect to the force signal (Vsig)
The resistance ratio and resistance values are set as plotted above.
Resistance R_{twenty one}~ R_2nInput signal (Vsig)
Is plotted on the curve of the brightness correction characteristic D in FIG.
The resistance ratio is set as follows. The resistance R_{twenty one}~ R _2n
Is the resistance R in the case of the brightness correction characteristic D in FIG._{twenty one}~ R_2n
Is the same as.

Further, the control circuit 13 in the LCD driver IC 11 sends out a control output CONT based on an instruction of a brightness correction changeover switch (not shown) connected to the LCD driver IC 11. Switch SW _1- S
This control output CONT causes W _n
The fixed contacts a or b on the _{11 to} R _1n side or the resistors R _{21 to} R _2n side can be switched all at once. Further, the scan driver IC 15 supplies a scan signal to the electrodes Y _{1 to} Y ₄₈₀ of the LCD 12.

Next, the operation will be described.

Control circuit 13 in LCD driver IC 11
Control output CONT based on an instruction from a brightness correction changeover switch (not shown).
4 to the switches SW _{1 to} S of the reference voltage generator 14.
All together W _n, the corresponding resistors R ₁₁ to R _1n side or resistor R ₂₁
Control is performed to switch to fixed contact a or b on the side of R _2n .

Here, when the switches SW _{1 to} SW _n are simultaneously switched to the fixed contacts a on the resistors R _{11 to} R _1n side, for example,
The luminance correction of the characteristic B of FIG. 2 is performed. Also, switch S
W _{1 to} SW _n are fixed contacts b on the resistance R _{21 to} R _2n side, for example.
When all are switched to, the brightness correction of the characteristic D of FIG. 3 is performed.

Therefore, when displaying an input signal that has not been subjected to the inverse γ correction on the LCD monitor as in the software of a computer, the switches SW _{1 to} SW _n are set to the resistors R ₁₁ by a brightness correction changeover switch (not shown). ~ R
LCD driver I so that it switches to fixed contact a on the _1n side.
When C11 is instructed, the control circuit 13 in the LCD driver IC 11 sends out the control output CONT to switch the switches SW ₁ to SW _n to the fixed contacts a on the resistors R _{11 to} R _1n side. As a result, the brightness correction of the characteristic B is performed and L
In addition to the original characteristic A of the CD 12, the luminance characteristic of the LCD monitor becomes a linear characteristic as shown in C of FIG. 2, and a natural image display can be obtained.

Further, when displaying an input signal which has been subjected to inverse γ correction such as a video signal on the LCD monitor, the switch SW is switched by a brightness correction changeover switch (not shown).
_When the LCD driver IC 11 is instructed to switch _{1 to} SW _n to the fixed contacts b on the side of the resistors R _{21 to} R _2n , the LCD
The control circuit 13 in the driver IC 11 sends out the control output CONT to set the switches SW ₁ to SW _n to the resistor R.
Switch to fixed contact b from _{21 to} R _2n side. As a result, the luminance correction of the characteristic D is performed, and the original characteristic A of the LCD 12 is combined with the luminance characteristic of the LCD monitor as shown in E (characteristic of γ value of about 2.2) in FIG. Display characteristics can be obtained.

The brightness correction changeover switch (not shown) may be a cyclic changeover switch such as a tact switch, or a mechanical changeover switch such as a slide switch, a seesaw switch, or a toggle switch. Good.

As can be seen from the above description, when a linear input image signal that has not been inversely γ-corrected is displayed on the LCD monitor as in software of a computer, the brightness is corrected so that the brightness characteristic becomes linear ( By applying B) in FIG. 2, an image having no discomfort in gradation display and color display can be obtained. Therefore, on the LCD monitor, both the video signal and the computer software can be viewed in a natural state.

In this embodiment, an LCD driver IC
A brightness correction changeover switch (not shown) connected to 11 has a brightness characteristic of γ value of about 2.2 according to the input image signal.
The control circuit within the LCD driver IC 11 is selected (instructed) whether to perform the brightness correction (D in FIG. 3) such that or the brightness correction (B in FIG. 2) such that it becomes linear. Although 13 detects this and switches the switches SW _{1 to} SW _n of the reference voltage generation unit 14, the present invention is not limited to this, and the control circuit 13 in the LCD driver IC 11 automatically inputs the input image signal. Brightness correction (D in FIG. 3) so that the brightness characteristic has a γ value of about 2.2, or brightness correction such that the brightness characteristic becomes linear (B in FIG. 2).
Switch S of the reference voltage generator 14 is selected.
The switching control of W _{1 to} SW _n may be performed.

[0026]

The image display device, the signal processing device of the present invention,
Further, according to the signal processing method, a control signal for applying γ correction of the luminance characteristic corresponding to the type of the input image digital signal is generated, and the type of the input image digital signal is changed based on the control signal. A corresponding reference voltage is selectively generated, and the reference voltage is used to γ-correct the input image digital signal to generate an analog signal to drive the display unit. When a linear input image signal that has not been subjected to the inverse γ correction is displayed on the LCD monitor as described above, the correction is performed so that the luminance characteristic becomes linear, so that an image having no discomfort in gradation display and color display is obtained. Is obtained. Therefore, LC
On the D monitor, the video signal and the computer software can be viewed in a natural state.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part showing an embodiment of a brightness correction device in a liquid crystal image display device according to the present invention.

FIG. 2 is a diagram showing an example of LCD brightness correction.

FIG. 3 is a diagram showing another example of LCD brightness correction.

FIG. 4 is a schematic view of a main part showing an example of a brightness correction device in a conventional LCD monitor.

[Explanation of symbols]

11 LCD driver IC 12 LCD 13 Control circuit 14 Reference voltage generator

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 641 G09G 3/20 641C 641Q H04N 5/202 H04N 5/202 F term (reference) 2H093 NA52 NC03 NC13 NC21 NC65 ND06 ND58 5C006 AA01 AA16 AA22 AC21 AF45 AF46 AF51 AF53 AF61 AF83 BC12 BF14 BF24 BF43 FA02 FA18 FA56 5C021 PA58 PA62 PA86 PA95 PA99 RB00 RB03 XA34 YB03 YA03 BB05 EE05 JJ04

Claims (3)

[Claims] 1. An image display device for receiving an input of an image digital signal corresponding to any one of a plurality of types of input signals having different brightness corrections and driving a display unit to display an image, It is possible to generate a control signal generation unit that generates a control signal for performing γ correction of the brightness characteristic corresponding to the type of the input image digital signal, and to generate a plurality of reference voltages for setting the brightness characteristic. And a reference voltage generator that selectively generates the reference voltage corresponding to the type of the input image digital signal based on the control signal generated by the control signal generator, and the reference voltage generator. A D / A for driving the display unit by γ-correcting the input image digital signal using the reference voltage generated by the unit to generate an analog signal.
An image display device comprising: a converter. 2. A signal processing apparatus for receiving an input of an image digital signal corresponding to any one of a plurality of types of input signals having different brightness corrections and driving a display unit to display an image. In, a control signal generating section for generating a control signal for γ-correcting the brightness characteristic corresponding to the type of the input image digital signal, and generating a plurality of reference voltages for setting the brightness characteristic And a reference voltage generator that selectively generates the reference voltage corresponding to the type of the input image digital signal based on the control signal generated by the control signal generator, and the reference voltage generator. Using the reference voltage generated by the voltage generator, the input image digital signal is γ-corrected to generate an analog signal for driving the display unit. Signal processing apparatus characterized by comprising a D / A converter. 3. A signal processing method for receiving an input of an image digital signal corresponding to any one of a plurality of types of input signals having different brightness corrections and driving a display unit to display an image. In, a control signal for applying a γ correction of a brightness characteristic corresponding to the type of the input image digital signal is generated, and the brightness corresponding to the type of the input image digital signal is generated based on the control signal. The reference voltage for setting the characteristic is selectively generated, and the reference voltage is used to γ-correct the input image digital signal to generate an analog signal for driving the display unit. A signal processing method characterized in that the signal is output as a signal.