JPH0563779B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a color liquid crystal panel driving circuit.

[Prior art and its problems] In recent years, liquid crystal television receivers that use a liquid crystal display panel in the display section have been put into practical use as small portable television receivers. Furthermore, recently, liquid crystal color televisions using color liquid crystal panels have been considered. There are various methods for color LCD display, but
As shown in Figure 2, R (red) and G
A color liquid crystal panel 2 is constructed by arranging primary color filters 1 of (green) and B (blue), and a drive electrode for R, a drive electrode for G, and a drive for B correspond to the R, G, and B color filters 1. Drive voltage for R, G for each electrode
Generally, color display is performed by applying a drive voltage for B and a drive voltage for B. In FIG. 2, 3 is a scanning electrode drive circuit, 4 is an R signal electrode drive circuit, 5 is a G signal electrode drive circuit, and 6 is a B signal electrode drive circuit. Also,
Reference numeral 7 denotes a liquid crystal voltage generation circuit that supplies operating voltages of V ₀ to V ₅ to each of the drive circuits 3, 4, 5, and 6. This liquid crystal voltage generation circuit 7 generates the R drive voltage,
Generates G drive voltage and B drive voltage.

FIG. 3 shows a part of a sectional view of the color liquid crystal panel 2. As shown in FIG. Color LCD panel 2
In this method, a pair of glass plates 11a and 11b are arranged facing each other with a predetermined distance therebetween, and a liquid crystal 12 is filled between them. Then, a transparent scanning electrode 13 is provided inside the glass plate 11a, and R, G, and B signal electrodes 14, 15, and 16 are arranged on the glass plate 11b, and furthermore, R, G, and B color electrodes are arranged on the glass plate 11b. Filters 17, 18, and 19 are provided. A deflection plate 20 is placed on the outside of the glass plates 11a and 11b.
a and 20b are arranged in a stacked manner.

Color filters 17, 18, 19 as above
are provided on the signal electrodes 14, 15, and 16, but because they are formed three times for each color of R, G, and B, it is extremely difficult to form them uniformly, resulting in variations in the filter film thickness. If there is a difference in filter film thickness, there is a problem in that even if the same voltage is applied to the electrodes, there will be a difference in the effective value applied to the liquid crystal, resulting in deterioration of display quality.

This is because the light transmittance changes depending on the film thickness of the filter.

Furthermore, even if the film thickness of the filter can be formed uniformly, as is well known as the relationship between Δn・d (Δn: anisotropy of the refractive index of liquid crystal, d: cell gap) and transmittance of the liquid crystal element. , because the transmittance of the R, G, and B color filters themselves is different.
There is a problem in that color balance deteriorates when the R, G, and B signal electrodes are driven with the same voltage.

[Object of the invention] The present invention has been made in view of the above points, and
An object of the present invention is to provide a color liquid crystal panel drive circuit that can correctly display a desired color and maintain good display quality even when R, G, and B filters have different transmittances.

[Key Points of the Invention] In a color liquid crystal panel drive circuit equipped with R, G, and B color filters having mutually different transmittances, a drive electrode for R, a drive electrode for G, and a drive electrode for B that correspond to the color filters are Different R drive voltages such that the ratio of the voltages applied to the R drive electrode, G drive electrode, and B drive electrode is the same for all drive electrodes when the same level of data is supplied. , a driving voltage for G, and a driving voltage for B are applied to correct the color balance.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 30 is a color liquid crystal panel similar to that explained in FIGS. 2 and 3, and this color liquid crystal panel 30 includes an R electrode driver 31, a G electrode driver 32, a B electrode driver 33, and a scanning electrode driver. The display is driven by 34. Each of the drivers 31, 32, 33, and 34 receives bias voltages from an R bias voltage generation circuit 35, a G bias voltage generation circuit 36, and a B bias voltage generation circuit 37, that is, an R drive voltage and a G drive voltage. ,
B drive voltage is supplied. Now, to explain the 1/13 bias as an example, the R bias voltage generation circuit 35 connects five resistors to the ground line GND.
It is connected in series with the V _CC power supply, the value of the resistor located in the center is 9R, the value of the other resistors is R, and the voltage from GND to V _CC is divided by 13 to obtain a voltage of V ₀ to V ₅ . ing. Then, the voltages V ₀ , V ₁ , V ₄ , and V ₅ are supplied to the scanning electrode driver 34, and the voltages V ₀ , V ₂ ,
Voltages V ₃ and V ₅ are supplied to the R electrode driver 31. Therefore, the bias ratio is determined by the duty of the color liquid crystal panel 30, and if the duty is 1/N and the bias ratio is b, then b=
It is expressed as √+1. The G bias voltage generation circuit 36 is formed by connecting three resistors in series, one end of which is connected to the ground line GND, and the other end connected to the sliding terminal of the variable resistor 361.
The variable resistor 361 is connected between the V _CC power supply and the V _CC ' power supply, and supplies its adjusted voltage to the bias voltage generation circuit 36 . This bias voltage generation circuit 36 has a resistor located at the center with a value of 9R and other resistors with values of R, and obtains voltages of V ₂ ′, V ₃ ′, and V ₅ ′, and supplies them to the G electrode together with the above V ₀ voltage. It is supplied to the driver 32. The B bias voltage generation circuit 37 is formed by connecting three resistors in series, one end of which is connected to the ground line GND, and the other end connected to the sliding terminal of the variable resistor 371. The variable resistor 371 is connected between the V _CC power supply and the V _CC ″ power supply, and its adjusted voltage is applied to the bias voltage generation circuit 37.
is supplied to. This bias voltage generation circuit 36
The value of the resistor located in the center is 9R, the value of the other resistors is R, and the voltages V ₂ ″, V ₃ ″, and V ₅ ″ are obtained and supplied to the B electrode driver 33 along with the above V ₀ voltage. There is.

When the film thickness of the color filter is the same (more precisely, when Δn・d of R, G, and B are the same), the light transmittance is in the relationship R>G>B, so each signal The bias voltage of the electrodes may be B>G>R. Furthermore, the variable resistors 361 and 371 may be fixed resistors whose resistance values are adjusted according to the transmittance of the color filter. Note that in FIG. 1, the signal lines of the display data system are omitted.

As mentioned above, in the embodiment shown in FIG.
Since each voltage adjustment circuit is provided by
By adjusting the voltage, the display color on the color liquid crystal panel 30 can be adjusted. That is, by variably operating the variable resistor 361, the voltage supplied to the bias voltage generation circuit 36 changes, and the voltages V ₂ ′, V ₃ ′, and V ₅ ′ supplied to the G electrode driver 32 change. Further, by variably operating the variable resistor 371, the voltage supplied to the bias voltage generation circuit 37 changes, and the supply voltages to the B electrode driver 33 are V ₂ ″, V ₃ ″,
In _other words, by adjusting the variable resistors 361 and 371, the R drive electrode, G
When the same level of data is supplied to the R drive electrode, the B drive electrode, and the B drive electrode, the ratio of the voltages applied to the R drive electrode, G drive electrode, and B drive electrode is the same for all drive electrodes. Different drive voltages for R, drive voltages for G, and B
A drive voltage is generated and supplied to the R electrode driver, G electrode driver, and B electrode driver.
Therefore, even if there are variations in the R, G, B filter film thickness, the variable resistors 361, 37
By adjusting 1, the effective values applied to the liquid crystal can be made the same for R, G, and B, and high display quality can be obtained.

In the above embodiment, a voltage adjustment circuit is provided in the G bias voltage generation circuit 36 and the B bias voltage generation circuit 37, but a voltage adjustment circuit is provided in the R, G or R, B bias voltage generation circuit. It's okay. Further, a voltage adjustment circuit may be provided in all the bias voltage generation circuits for R, G, and B.

[Effects of the Invention] As detailed above, according to the present invention, the R drive electrode, the G drive electrode, and
When the same level of data is supplied to the B drive electrode, the ratio of the voltages applied to the R drive electrode, the G drive electrode, and the B drive electrode is the same for all drive electrodes. Since we have provided a means to correct the color balance by applying different driving voltages for R, G, and B, it is possible to apply voltages that correspond to the transmittance of the R, G, and B filters. It is possible to improve the color balance.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention;
FIG. 2 is a diagram showing a conventional color liquid crystal panel driving method, and FIG. 3 is a sectional view showing a part of the liquid crystal display panel in FIG. 12...Liquid crystal, 13...Scanning electrode, 14, 15, 1
6... Signal electrode, 17, 18, 19... Color filter, 30... Color liquid crystal panel, 31... R electrode driver, 32... G electrode driver, 33... B electrode driver, 34... Scanning electrode driver, 35, 36, 3
7...Bias voltage generation circuit, 361, 362...Variable resistor.

Claims (1)

[Scope of Claims] 1. In a color liquid crystal panel drive circuit equipped with R, G, and B color filters having mutually different transmittances, an R drive electrode corresponding to the color filter;
When the same level of data is supplied to the G drive electrode and the B drive electrode, the ratio of the voltages applied to the R drive electrode, the G drive electrode, and the B drive electrode is the same for all drive electrodes. Different R drive voltages and G drive voltages that are equal to each other,
A color liquid crystal panel drive circuit, characterized in that it is provided with means for applying a B drive voltage and correcting color balance.