JP2005316460A - Liquid crystal display and method for driving the liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein a liquid crystal display using the conventional OCB (optically compensated bend) mode displays luminance different from actually desired luminance, when the temperature changes. <P>SOLUTION: The liquid crystal display is equipped with a liquid crystal display panel 2 which has source signal lines and gate signal lines arranged in a matrix and has liquid crystal display elements, using an OCB mode liquid crystal disposed on the intersections of the source signal lines and the gate signal lines; a gate driver 3 which supplies gate signals to the gate signal lines; a source driver 4 which supplies source signals to the source signal lines; a temperature-detecting means 7 which detects temperature; and a correction means 6 which corrects the display data to generate source signals into display data, according to the detected temperature, wherein the source signals are generated on the basis of the corrected display data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device using an OCB mode liquid crystal and a driving method of the liquid crystal display device.

  Liquid crystal display devices are thin and lightweight, and their use has been expanded in recent years as an alternative to conventional cathode ray tubes. However, currently widely used TN (Twisted Nematic) oriented liquid crystal panels have a narrower viewing angle, a slower response speed, and appear to have a tail when displaying moving images, so that the image quality is inferior to that of a cathode ray tube.

  On the other hand, in recent years, a liquid crystal display device using an OCB (Optically Compensated Bend) mode having features of a high-speed response and a wide viewing angle has been used. In this liquid crystal display device, a liquid crystal is bent to perform visual compensation, and an optical phase compensation film is combined with this to obtain a wide viewing angle.

  FIG. 12 is a schematic cross-sectional view of a liquid crystal display device using the OCB mode. 12A and 12B are schematic cross-sectional views of the voltage application state of the liquid crystal display device using the OCB mode, and FIG. 12C is a voltage non-application state of the liquid crystal display device using the OCB mode. FIG.

  Nematic liquid crystal is injected between the glass substrates 51 constituting the liquid crystal display device using the OCB mode, as shown as liquid crystal molecules 52 in FIG. The orientation state is called a splay state 53. By applying a relatively large voltage to the liquid crystal layer when the liquid crystal display device is turned on, the splay state 53 shown in FIG. 12C is changed to the bend states 54a and 54b shown in FIGS. 12A and 12B. Let The display using the bend states 54a and 54b is a characteristic of the OCB mode, and the transmittance of the panel is changed by changing the voltage level. A bend state 54a shown in FIG. 12A indicates a bend state when white is displayed, and a bend state 54b shown in FIG. 12B indicates a bend state when black is displayed. .

  FIG. 13 shows the relationship between the voltage and the luminance of the liquid crystal display device using the OCB mode. 55 indicates the relationship between the voltage and the luminance when the temperature is 30 degrees Celsius, and 56 indicates the relationship between the voltage and the luminance when the temperature is 55 degrees Celsius. When the temperature is 30 degrees Celsius, with respect to the relationship between the voltage and the luminance, as shown in 55, the luminance decreases as the voltage increases, the luminance becomes the minimum at the position of Q, and then the voltage increases. As the brightness increases slightly. Thus, when the voltage increases from the position of Q, the luminance starts to increase, but this tendency is also observed in the TN liquid crystal, but the degree of increase in the luminance is much larger than that of the TN liquid crystal. When the temperature is 55 degrees Celsius, as shown in 56, the relationship between the voltage and the luminance decreases as the voltage increases, and the luminance becomes minimum at the position of the point P, and then the voltage increases. As it goes on, the brightness increases slightly. Thus, when the voltage increases from the position of P, the luminance starts to increase, but this tendency is also observed in the TN liquid crystal, but the degree of increase in the luminance is much larger than that of the TN liquid crystal. Thus, the relationship between brightness and voltage changes as the temperature changes.

  FIG. 14 shows the relationship between the gray level near the voltage at which the luminance is minimum and the luminance at 30 degrees Celsius, 45 degrees, and 55 degrees Celsius, and the luminance. The gradation at which the luminance is minimum increases as the temperature increases. Since the liquid crystal display device using the OCB mode is normally white, in terms of voltage, the voltage at which the luminance is minimum decreases as the temperature increases. As described above, the relationship between the voltage and the luminance of the liquid crystal display device using the OCB mode changes as the temperature changes, and in particular, the gradation (voltage) at which the luminance is minimized becomes larger (smaller) as the temperature increases. go.

  Further, in the gradation having a value smaller than the gradation having the minimum luminance, the luminance increases as the gradation decreases, and this tendency is also observed in the TN liquid crystal, but this tendency is much higher than that in the TN liquid crystal. large. As for the voltage, as described above, at a voltage higher than the voltage at which the luminance is minimized, the luminance increases as the voltage increases. This tendency is also observed in the TN liquid crystal, but the degree of increase in luminance is much larger than that in the TN liquid crystal.

  However, as can be seen in the TN alignment liquid crystal display device, particularly in the liquid crystal display device using the OCB mode, when the temperature is increased, the voltage at which the luminance is minimized becomes small. Nevertheless, it sometimes appears bright. In other words, if the voltage at which the luminance is minimized before being increased in temperature is applied after the temperature has been increased, the voltage at which the luminance is minimized after the temperature is increased is reduced so that it is displayed brightly. It will be.

  Further, since the relationship between the luminance and the voltage changes according to the temperature, when the temperature changes, a luminance different from the luminance that is actually desired to be displayed is displayed.

  That is, in the conventional liquid crystal display device using the OCB mode, even when the temperature is increased, even when black display is performed, the optical compensation cannot be performed and black is displayed brightly, and the contrast is reduced. is there.

  In addition, the conventional liquid crystal display device using the OCB mode has a problem that when the temperature changes, a luminance different from the luminance that is actually displayed is displayed.

  In view of the above problems, an object of the present invention is to provide a liquid crystal display device capable of displaying black with the minimum luminance even when the temperature increases, and a driving method of the liquid crystal display device.

  Another object of the present invention is to provide a liquid crystal display device capable of displaying the desired luminance even when the temperature changes, and a driving method of the liquid crystal display device in consideration of the above problems.

In order to solve the above-described problem, the first aspect of the present invention provides:
A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A source driver for supplying a source signal to the source signal line;
Temperature detecting means for detecting the temperature;
A liquid crystal display device comprising source driver driving means for supplying a source driver driving voltage corresponding to the detected temperature to the source driver.

The second aspect of the present invention
A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A source driver for supplying a source signal to the source signal line;
Temperature detecting means for detecting the temperature;
Correction means for correcting display data for generating the source signal to display data corresponding to the detected temperature;
The source signal is a liquid crystal display device that is generated based on the corrected display data.

The third aspect of the present invention
In the liquid crystal display device of the second aspect of the present invention, the correction means corrects the display data by performing gamma correction according to the detected temperature.

The fourth aspect of the present invention is
When the correction means corrects the display data, the value of the display data whose value is 0 in the display data is corrected to a first value that is a value corresponding to the detected temperature,
Of the display data, the second value, which is the value of the display data whose signal level is other than 0, is set from the third value to the first value with the maximum value of the display data as the third value. In the liquid crystal display device according to the second aspect of the present invention, the first value is added to the value obtained by multiplying the value obtained by subtracting the value by the third value multiplied by the second value. .

The fifth aspect of the present invention provides
In the liquid crystal display device according to the second aspect of the present invention, the correction means corrects the display data in which the value of the display data is not more than a predetermined value.

The sixth aspect of the present invention provides
The liquid crystal display element is a liquid crystal display device according to the first or second aspect of the present invention, which is a liquid crystal display element using OCB mode liquid crystal.

The seventh aspect of the present invention
A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A liquid crystal display device driving method for driving a liquid crystal display device comprising a source driver for supplying a source signal to the source signal line,
A temperature detection step for detecting the temperature;
And a source driver driving step for supplying a source driver driving voltage corresponding to the detected temperature to the source driver.

In addition, the eighth aspect of the present invention
A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A liquid crystal display device driving method for driving a liquid crystal display device comprising a source driver for supplying a source signal to the source signal line,
A temperature detection step for detecting the temperature;
A correction step of correcting display data for generating the source signal into display data corresponding to the detected temperature,
The source signal is a method of driving a liquid crystal display device that is generated based on the corrected display data.

The ninth aspect of the present invention provides
The liquid crystal display element is a liquid crystal display element using OCB mode liquid crystal, or the driving method of the liquid crystal display device of the seventh or eighth aspect of the present invention.

  The present invention can provide a liquid crystal display device capable of displaying black with the minimum luminance even when the temperature increases, and a driving method of the liquid crystal display device.

  In addition, the present invention can provide a liquid crystal display device capable of displaying a luminance desired to be displayed even when the temperature changes, and a driving method of the liquid crystal display device.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
First, the first embodiment will be described.

  FIG. 1 shows a block diagram of a liquid crystal display device 1 according to the first embodiment.

  The liquid crystal display device 1 is a liquid crystal display device using OCB mode liquid crystal.

  The liquid crystal display device 1 includes a liquid crystal display panel 2, a gate driver 3, a source driver 4, a liquid crystal drive voltage generation circuit 5, a controller circuit 6, a temperature detection unit 7, an input power supply 8, and a display data generation unit 9.

  The liquid crystal display panel 2 is a display panel having liquid crystal display elements using OCB mode liquid crystal provided at the intersections of source signal lines and gate signal lines and source signal lines and gate signal lines arranged in a matrix.

  The gate driver 3 is a circuit that supplies a selection scanning signal for performing line sequential scanning to each gate signal line of the liquid crystal display panel 2.

  The source driver 4 is a circuit that supplies an image signal voltage to each source signal line of the liquid crystal display panel 2.

  The liquid crystal drive voltage generation circuit 5 supplies a source driver drive voltage (AVDD) to the source driver 4, supplies a gate driver drive voltage (VGG, VEE) to the gate driver 3, and outputs a counter signal. This is a circuit for supplying a counter signal electrode drive voltage (VCOM) to the electrodes.

  The controller circuit 6 is a circuit that controls image signal processing and drive timing. The controller circuit 6 includes an image signal processing circuit 10 and a timing control circuit 11 as shown in FIG. The image signal processing circuit 10 inputs the input display data generated by the display data generation means 9, corrects the input display data to display data corresponding to the temperature detected by the temperature detection means 7, and corrects the display data. Is a circuit that outputs a display signal corresponding to. The timing control circuit 11 is a circuit that sends a timing control signal to the source driver 4, the gate driver 3, and the liquid crystal drive voltage generation circuit 5.

  The temperature detection means 7 is means for detecting the temperature of the liquid crystal display panel 2.

  The input power supply 8 is means for supplying power for operating the liquid crystal display device 1.

  The display data generation unit 9 is a unit that generates display data to be displayed on the liquid crystal display panel 2, and is a unit that reads and reads image data stored in a frame buffer, for example.

  The image signal processing circuit 10 according to the present embodiment is an example of the correction unit of the present invention.

  Next, the operation of this embodiment will be described.

  The input power supply 8 is supplied to the controller circuit 6 and the liquid crystal drive voltage generation circuit 5, and first, the controller circuit 6 starts up. The controller circuit 6 sends an image display signal and a timing control signal to the source driver 4, sends a timing control signal to the gate driver 3, and sends a timing control signal to the liquid crystal drive voltage generation circuit 5.

  The liquid crystal drive voltage generation circuit 5 supplies a source driver drive voltage (AVDD) to the source driver 4, supplies a gate driver drive voltage (VGG, VEE) to the gate driver 3, and outputs a counter signal. A display operation can be performed by supplying the counter signal electrode drive voltage (VCOM) to the electrodes.

  On the other hand, the temperature detection means 7 detects the temperature of the liquid crystal display panel 2 and outputs the temperature detection result to the image signal processing circuit 10. The image signal processing circuit 10 inputs the input display data generated by the display data generation means 9, corrects the input display data to display data corresponding to the temperature detected by the temperature detection means 7, and corrects the display data. A display signal corresponding to is output.

  That is, the image signal processing circuit 10 holds a gamma correction table for performing gamma correction in accordance with the temperature of the liquid crystal display panel 2 detected by the temperature detecting means 7, and the gamma correction in accordance with the detected temperature. Gamma correction of input display data is performed using the correction table. FIG. 3 shows an example of a gamma correction table corresponding to the detected temperature. FIG. 3 shows, as an example, how each gradation is converted when the temperature of the liquid crystal display panel 2 is increased to 60 degrees Celsius with reference to the temperature of the liquid crystal display panel 2 being 30 degrees Celsius. A gamma correction table is shown. The gamma correction table shown in FIG. 3 is based on the case where the temperature is 30 degrees Celsius. When the temperature is increased to 60 degrees Celsius, the gradation of the display data is displayed in order to display the same luminance even if the temperature is changed. It is obtained by measuring in advance whether it should be changed.

  As described with reference to FIG. 14, when the temperature rises, the gray level at which the luminance is minimum increases in the relationship between the gray level and the luminance. Therefore, with reference to the case where the temperature of the liquid crystal display panel 2 is 30 degrees Celsius, when the temperature of the liquid crystal display panel 2 rises to 60 degrees Celsius, gamma correction is performed so that the gradation of the input display data is increased. There is a need. For example, as is apparent from FIG. 3, when the temperature of the liquid crystal display panel is 60 degrees Celsius, the gradation of the input display data whose gradation is 0 is converted to 32. Further, the gradation of the display data having the gradation of 64 is converted to the gradation of 74.

  Even when the temperature of the liquid crystal display panel 2 is other than 60 degrees Celsius, in order to display the same luminance even when the temperature is changed when the temperature is changed on the basis of the temperature of the liquid crystal display panel being 30 degrees Celsius If it is measured in advance how to change each gradation of display data, a gamma correction table corresponding to the temperature can be obtained.

  Since the image signal processing circuit 10 performs gamma correction of the input display data using such a gamma correction table corresponding to the temperature, it can display black even if the temperature increases, and the temperature changes. However, it is possible to display the desired brightness.

  In this embodiment, when creating a gamma correction table, display data is used to display the same luminance even if the temperature changes when the temperature changes with reference to the case where the temperature is 30 degrees Celsius. However, the reference temperature is not limited to 30 degrees Celsius, and other temperatures may be used.

  Although the present embodiment has been described on the assumption that gamma correction is performed over all gradations of input display data, the present invention is not limited to this. Of the gradations of the input display data, only the low gradation part may be gamma corrected.

  That is, when gamma correction is performed only for the black gradation, the continuity of the input display data is lost by performing gamma correction. Accordingly, in order to maintain the continuity of the input display data, only the low gradation portion of the gradation of the input display data may be gamma corrected.

  Further, when gamma correction is performed on the high gradation part, there is a problem that white is colored as compared with the low gradation part. Therefore, as shown in FIG. 4, by correcting the input display data whose value is equal to or less than a predetermined value among the input display data, it is possible to avoid the problem that the white display is colored in the high gradation portion.

  For example, in FIG. 4, it can be seen that only the low gradation part (high voltage part) where the gradation of the input display data is less than 128 is gamma corrected.

  Furthermore, although the present embodiment has been described as performing gamma correction according to the temperature of the liquid crystal display panel 2 on the input display data, correction other than gamma correction can be applied to the input display data. FIG. 5 shows a method for correcting such input display data.

  That is, in FIG. 5, how to correct the gradation of the input display data when the temperature of the liquid crystal display panel 2 is 30 degrees and the temperature of the liquid crystal display panel 2 is 60 degrees Celsius. Is shown. That is, when the temperature in FIG. 5 is 30 degrees Celsius, the gradation is 0, that is, the gradation of black display corresponds to the Q point in the relationship 55 between the voltage and the luminance at 30 degrees Celsius described in FIG. In FIG. 13, the point Q at which the luminance is minimized as the temperature increases moves in the direction in which the voltage (gradation) is small (large), for example, as point P. Further, in order to perform black display when the temperature increases, it is necessary to set the voltage (gradation) corresponding to the point where the luminance is minimized. In FIG. 5, when the gray level of the input display data is 0 to perform black display at a temperature of 30 degrees Celsius, the gray level can be displayed even if the temperature changes. Need to be converted to 32. Thus, the gradation corresponding to black display when the temperature is 30 degrees Celsius is 0, but when the temperature is increased to 60 degrees Celsius, the gradation corresponding to black display is 32.

  The gradation conversion of the input display data other than the black display is performed as follows. For example, when the temperature is 30 degrees Celsius, the gradation 64 has a length from gradation 0 to gradation 64 as B, a length from gradation 0 to gradation 255 as A, and from gradation 32 to gradation. When the length up to the key 255 is A ′ and the length from the gradation 32 to the converted gradation is B ′, the gradation 64 in the case of 30 degrees Celsius so that the following equation 1 is satisfied. Converted.

(Equation 1)
A: A ′ = B: B ′
From Equation 1, it can be seen that gradation 64 is converted to gradation 88. Note that other gradations other than gradation 64 are also converted according to Equation 1.

  In other words, the gradation of black display at 30 degrees Celsius is 0, the gradation of black display at 60 degrees Celsius is L1, the gradation before conversion at 30 degrees Celsius is X1, and the maximum gradation When the value is Lmax, the gradation X1 before conversion is converted to the gradation X2 after conversion at 60 degrees Celsius based on the following formula 2.

(Equation 2)
X2 = L1 + (Lmax−L1) × X1 / Lmax
Further, Equation 2 can be used for gradation conversion even when the temperature is other than 60 degrees Celsius. That is, even when the temperature is a temperature T other than 60 degrees Celsius, the black display gradation at the temperature T is L1, that is, the gradation 0 at 30 degrees Celsius is converted to the gradation L1 at the temperature T. When the gradation before conversion at 30 degrees Celsius is X1 and the maximum value of the gradation is Lmax, the gradation X2 after conversion when the temperature is T can be obtained using Equation 2.

  In this way, by using Equation 2, when the temperature is 30 degrees Celsius, the gradation after the temperature change can be obtained when the temperature of the liquid crystal display panel 2 changes. The image signal processing circuit 10 calculates the gradation of the input display data after conversion when the temperature changes using Equation 2 with reference to the gradation when the temperature is 30 degrees Celsius, and outputs it as a display signal. As described above, the image signal processing circuit 10 converts the gradation of the input display data according to the temperature, so that the same effect as that of the gamma correction of the input display data can be obtained. In addition, when a table for converting the gray level before gamma correction to the gray level after gamma correction is used for gamma correction, this table is stored in the controller of the liquid crystal display device. It is necessary to provide a memory and store this table in this memory. However, in this embodiment, since such a table is not used and the gradation after the temperature is changed is obtained using Equation 2, it is not necessary to provide a memory in the controller of the liquid crystal display device. You can save money.

(Second Embodiment)
Next, a second embodiment will be described.

  FIG. 6 is a block diagram of the liquid crystal display device 12 according to the second embodiment.

  The liquid crystal display device 12 is a liquid crystal display device using OCB mode liquid crystal as in the first embodiment.

  The liquid crystal display device 12 includes a liquid crystal display panel 2, a gate driver 3, a source driver 4, a liquid crystal drive voltage generation circuit 13, a controller circuit 14, temperature detection means 7, and an input power supply 8. In the second embodiment, a display data generation circuit is provided as in the first embodiment, but is not shown for simplicity.

  The liquid crystal display device 12 of the second embodiment is different from the liquid crystal display device 1 of the first embodiment in the controller circuit and the liquid crystal drive voltage generation circuit 13.

  In other words, the controller circuit 14 is a circuit that controls image signal processing and drive timing, but unlike the first embodiment, the controller circuit 14 is a circuit that does not correct input data according to temperature.

  Further, as shown in FIG. 7, the liquid crystal drive voltage generation circuit 13 is a multi-output circuit comprising a source driver drive voltage generation circuit 15, a gate driver drive voltage generation circuit 16, and a counter signal voltage generation circuit 17. is there. That is, the source driver drive voltage generation circuit 15 of the liquid crystal drive voltage generation circuit 13 is a circuit that supplies the source driver drive voltage (AVDD) to the source driver 9. The gate driver drive voltage generation circuit 16 of the liquid crystal drive voltage generation circuit 13 is a circuit that supplies a gate driver drive voltage (VGG, VEE) to the gate driver 10. The counter signal voltage generation circuit 17 of the liquid crystal drive voltage generation circuit 13 is a circuit that supplies the counter signal electrode drive voltage (VCOM) to the counter signal electrode.

  The source driver drive voltage generation circuit 15 is a circuit that supplies the source driver drive voltage (AVDD) corresponding to the temperature of the liquid crystal display panel 2 detected by the temperature detection means to the source driver.

  Since other than that is the same as that of 1st Embodiment, description is abbreviate | omitted.

  The source driver drive voltage generation circuit 15 of this embodiment is an example of the source driver drive means of the present invention.

  Next, the operation of this embodiment will be described.

  The input power supply 8 is supplied to the controller circuit 14 and the liquid crystal drive voltage generation circuit 13, and the controller circuit 14 is first activated. The controller circuit 14 sends an image display signal and a timing control signal to the source driver 4, sends a timing control signal to the gate driver 3, and sends a timing control signal to the liquid crystal drive voltage generation circuit 13.

  The source driver drive voltage generation circuit 15 of the liquid crystal drive voltage generation circuit 13 supplies the source driver drive voltage (AVDD) to the source driver 4. Further, the gate driver drive voltage generation circuit 16 of the liquid crystal drive voltage generation circuit 13 supplies the gate driver 3 with gate driver drive voltages (VGG, VEE). The counter signal voltage generation circuit 17 of the liquid crystal drive voltage generation circuit 13 supplies the counter signal electrode drive voltage (VCOM) to the counter signal electrode. Thus, the display operation of the liquid crystal display device 12 can be performed.

  On the other hand, the temperature detection means 7 detects the temperature of the liquid crystal display panel 2 and outputs the temperature detection result to the source driver drive voltage generation circuit 15 of the liquid crystal drive voltage generation circuit 13. The source driver drive voltage generation circuit 15 supplies the source driver drive voltage (AVDD) corresponding to the temperature detected by the temperature detection means 7 to the source driver 4. The source driver drive voltage (AVDD) is an analog voltage of the source driver 4.

  FIG. 8 shows the relationship between the gradation of the input display data and the output voltage of the source driver 4 and the source driver drive voltage (AVDD). In FIG. 8, the source driver drive voltage (AVDD) when the temperature of the liquid crystal display panel is 30 degrees Celsius is shown as AVDD (30 degrees) 18. In FIG. 8, the source driver driving voltage (AVDD) when the temperature of the liquid crystal display panel is 60 degrees Celsius is shown as AVDD (60 degrees) 19. AVDD (60 degrees) 19 has a lower voltage than AVDD (30 degrees) 18. That is, as described with reference to FIG. 13, when the temperature rises, the voltage at which the luminance is minimized becomes smaller in the relationship between the voltage and the luminance. Accordingly, when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius, the voltage at which the luminance is minimized is smaller than when the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. The voltage with the lowest luminance is a voltage corresponding to the source driver drive voltage (AVDD) in the case of black display, that is, the voltage. Therefore, the source driver drive voltage generation circuit 15 sets AVDD (60 degrees) 19 to a lower voltage than AVDD (30 degrees) 18.

  In this way, by setting AVDD (30 degrees) 18 and AVDD (60 degrees) 19 to voltages at which the luminance is minimized at the temperature of each liquid crystal display panel 2, even in the case of black display, optical It is possible to improve the problem that black cannot be compensated and the black color is displayed brightly and the contrast is reduced.

  Further, the source driver drive voltage generation circuit 15 sets the source driver drive voltage (AVDD) to a voltage corresponding to the temperature of the liquid crystal display panel 2 detected by the temperature detection means 7, so that the source driver 4 in each gradation is transferred to the source driver 4. Output voltage changes. For example, as shown in FIG. 8, the source driver drive voltage (AVDD) is set lower when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius than when the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. Thus, the output voltage to the source driver 4 at each gradation is lower when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius than when the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. Thus, by changing the source driver drive voltage (AVDD) according to the temperature, the output voltage to the source driver 4 at each gradation can also be changed. Accordingly, it is possible to display the desired luminance even when the temperature of the liquid crystal display panel 2 changes.

  FIG. 9 shows an example of the configuration of the source driver drive voltage generation circuit 15 that can set the source driver drive voltage (AVDD) to a voltage corresponding to the temperature of the liquid crystal display panel 2 detected by the temperature detection means 7. .

  The source driver drive voltage generation circuit 15 includes a voltage control circuit 42 and n−1 resistors 43a, 43b,... 43n−1. The voltage control circuit 42 is supplied with the power supply voltage from the input power supply 8 through the terminal 40, and receives a temperature detection signal including information on the temperature detected by the temperature detection means 7 through the terminal 41, and a source corresponding to the temperature This is a circuit for outputting a driver driving voltage (AVDD). The output of the voltage control circuit 42 is connected to a circuit that resistance-divides the output voltage of the voltage control circuit 42 by n resistors 43a, 43b,... 43n. From the circuit that resistance-divides the output voltage of the voltage control circuit 42, n source voltages Vref0, Vref1,..., Vrefn obtained by resistance-dividing the source driver driving voltage (AVDD) and the source driver driving voltage (AVDD). -1 is output.

  Next, the operation of the source driver drive voltage generation circuit 15 shown in FIG. 9 will be described.

  A power supply voltage supplied from the input power supply 8 is supplied to the terminal 40. Further, a temperature detection signal including information about the temperature detected by the temperature detection means 7 is input to the terminal 41.

  For example, as shown in FIG. 8, the voltage control circuit 42 applies the voltage supplied from the input power supply 40 when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius than when the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. In this case, the source driver drive voltage (AVDD) is set lower. That is, the output voltage to the source driver 4 at each gradation is lower when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius than when the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. In this way, the voltage control circuit 42 changes the source driver drive voltage (AVDD) according to the temperature.

  The source driver drive voltage (AVDD), which is the output of the voltage control circuit 42, is divided into resistors by a circuit composed of n resistors 43a, 43b,... 43n-1, and a source driver drive voltage is generated. The circuit 15 outputs the source driver driving voltage (AVDD) and n voltages Vref0, Vref1,. These output voltages are supplied to the source driver 4 via a flexible printed circuit board (not shown).

  The source driver 4 generates a voltage corresponding to each gradation using AVDD, n kinds of voltages Vref0, Vref1,... Vrefn-1.

  As described above, the voltage control circuit 42 of the source driver drive voltage generation circuit 15 shown in FIG. 9 corrects only the source driver drive voltage (AVDD) corresponding to the black voltage according to the temperature, so that the voltage other than black can be obtained. Each voltage such as Vref0 and Vref1 corresponding to the gradation can be automatically determined in a balanced manner. In addition, the source driver drive voltage generation circuit 15 decreases the output voltage such as the source driver drive voltage (AVDD), Vref0, Vref1,... Vrefn-1 as the temperature rises. As the temperature rises, the average power consumed by the liquid crystal display device 12 can be reduced. Therefore, even when the temperature rises, generation of heat from the liquid crystal display device 12 can be prevented.

  In the first embodiment, digital processing for correcting the gradation of the display data is performed. In this case, when the temperature rises, the data displayed as a result of correction is corrected. It may happen that the number of gradations that can be taken decreases. For example, in the case shown in FIG. 5, when the panel temperature is 30 degrees Celsius, the display data has 256 gradations, but when the panel temperature rises to 60 degrees Celsius, the display data has gradations. Correction is made within the range of 32 to 255. That is, the number of gradations is 224, and the number of gradations of the display data actually displayed is reduced.

  On the other hand, in the second embodiment, AVDD supplied to the source driver 4 and n kinds of voltages Vref0, Vref1,... Vrefn−1 are corrected in an analog manner, and therefore, between the gradations of the display data. Even if the difference in voltage value is reduced, the number of gradations of the display data is not reduced.

  In FIG. 9, instead of providing the voltage control circuit 42 and the temperature detecting means 7, it is also possible to connect the terminal 40 directly to the resistor 43a and use a thermistor as the resistor 43a. That is, the resistor 43a is supplied with a fixed source driver driving voltage (AVDD) that does not change with temperature, but the resistor 43a is a thermistor, so its resistance value changes with temperature. . Therefore, the voltage of Vref0, Vref1,... Vrefn−1 and the like changes according to the temperature by the resistor 43a. Therefore, even with such a configuration, the same effect as in FIG. 9 can be obtained.

  As illustrated in FIG. 9, the source driver drive voltage generation circuit 15 is not limited to the source driver drive voltage (AVDD) corrected according to the temperature, but is fixed to the source driver drive voltage (AVDD). Thus, Vref0 and the like can be corrected according to the temperature.

  FIG. 10 shows an example of the configuration of the source driver drive voltage generation circuit 15 that sets Vref0 to a voltage corresponding to the temperature of the liquid crystal display panel 2 detected by the temperature detection means 7.

  10 includes a first voltage control circuit 42a, a second voltage control circuit 42b, and n−1 resistors 43a, 43b,... 43n−1. ing.

  The first voltage control circuit 42a is a circuit that receives a power supply voltage from the input power supply 8 by a terminal 40a and generates a source driver drive voltage (AVDD) that is a fixed voltage that does not vary with temperature. The second voltage control circuit 42b receives the supply of the power supply voltage from the input power supply 8 through the terminal 40b, and also receives a temperature detection signal including information related to the temperature detected by the temperature detection means 7 through the terminal 41, according to the temperature. This is a circuit for outputting the voltage Vref0. The output of the first voltage control circuit 42a is connected to a resistor 43a of a circuit that resistance-divides the output voltage of the voltage control circuit 42 by n resistors 43a, 43b,... 43n, and the second voltage control circuit The output of 42b is connected to the connection point between the resistor 43a and the resistor 43b.

  Next, the operation of the source driver drive voltage generation circuit 15 shown in FIG. 10 will be described.

  The power supply voltage supplied from the input power supply 8 is supplied to the terminals 40a and 40b. Further, a temperature detection signal including information about the temperature detected by the temperature detection means 7 is input to the terminal 41.

  The first voltage control circuit 42a generates a fixed source driver driving voltage whose voltage value does not change with temperature from the power supply voltage supplied from the terminal 40a, and supplies the source driver driving voltage to the resistor 43a.

  On the other hand, the second voltage control circuit 42b uses the power supply voltage supplied from the terminal 40b and the temperature detection signal input from the terminal 41 as compared with the case where the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. The output voltage is set lower when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius. That is, the output voltage from the second voltage control circuit 42b is lower when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius than when the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. Thus, the second voltage control circuit 42b changes the output voltage according to the temperature.

  Accordingly, the source driver drive voltage (AVDD) supplied by the first voltage control circuit 42a is a fixed voltage that does not change according to the temperature, but Vref0 supplied by the second voltage control circuit 42b depends on the temperature. Since the voltage varies, the voltage is divided by a circuit composed of n resistors 43a, 43b,... 43n-1, and the source driver drive voltage generation circuit 15 AVDD) and n different voltages Vref0, Vref1,... Vrefn−1 obtained by resistance division. These output voltages are supplied to the source driver 4 via a flexible printed circuit board (not shown).

  The source driver 4 generates a voltage corresponding to each gradation using AVDD, n kinds of voltages Vref0, Vref1,... Vrefn-1.

  As described above, the second voltage control circuit 42b of the source driver drive voltage generation circuit 15 shown in FIG. 10 automatically corrects each voltage such as Vref1 corresponding to each gradation only by correcting Vref0 according to the temperature. Can be determined. Moreover, the source driver drive voltage generation circuit 15 reduces the output voltages of Vref0, Vref1,... Vrefn-1, etc. as the temperature rises, that is, as the temperature rises, the liquid crystal display device Since the average power consumed by 12 can be reduced, the generation of heat from the liquid crystal display device 12 can be prevented even when the temperature rises.

  In the first embodiment, digital processing for correcting the gradation of the display data is performed. In this case, when the temperature rises, the data displayed as a result of correction is corrected. It can happen that the number of tones of the image becomes smaller. For example, in the case shown in FIG. 5, when the panel temperature is 30 degrees Celsius, the display data has 256 gradations, but when the panel temperature rises to 60 degrees Celsius, the display data has gradations. Correction is made within the range of 32 to 255. That is, the number of gradations becomes 224, and the number of gradations that can be taken by the display data actually displayed is reduced.

  On the other hand, in the second embodiment, AVDD supplied to the source driver 4 and n kinds of voltages Vref0, Vref1,... Vrefn−1 are corrected in an analog manner, and therefore, between the gradations of the display data. Even if the difference in voltage value is reduced, the number of gradations of the display data is not reduced.

  In the source driver drive voltage generation circuit 15 of FIG. 10, Vref0 is corrected according to the temperature. However, not only Vref0 but also Vrefn-1 can be corrected according to the temperature.

  FIG. 11 shows an example of the configuration of the source driver drive voltage generation circuit 15 that corrects both Vref0 and Vrefn-1.

  The source driver drive voltage generation circuit 15 shown in FIG. 11 includes a first voltage control circuit 42a, a second voltage control circuit 42c, and n−1 resistors 43a, 43b,... 43n−1. ing.

  The first voltage control circuit 42a is a circuit that receives a power supply voltage from the input power supply 8 by a terminal 40a and generates a source driver drive voltage (AVDD) that is a fixed voltage that does not vary with temperature. The second voltage control circuit 42c is supplied with the power supply voltage from the input power supply 8 through the terminal 40b, and receives a temperature detection signal including information related to the temperature detected by the temperature detection means 7 through the terminal 41, according to the temperature. The circuit outputs the voltage Vref0 and Vrefn-1 corresponding to the temperature. The output of the first voltage control circuit 42a is connected to a resistor 43a of a circuit that resistance-divides the output voltage of the voltage control circuit 42 by n resistors 43a, 43b,... 43n, and the second voltage control circuit The output of 42c is connected to the connection point between the resistor 43a and the resistor 43b and the resistor 42n-1.

  Next, the operation of the source driver drive voltage generation circuit 15 shown in FIG. 11 will be described.

  The power supply voltage supplied from the input power supply 8 is supplied to the terminals 40a and 40b. Further, a temperature detection signal including information about the temperature detected by the temperature detection means 7 is input to the terminal 41.

  The first voltage control circuit 42a generates a fixed source driver driving voltage whose voltage value does not change with temperature from the power supply voltage supplied from the terminal 40a, and supplies the source driver driving voltage to the resistor 43a.

  On the other hand, the second voltage control circuit 42c uses the power supply voltage supplied from the terminal 40b and the temperature detection signal input from the terminal 41, so that the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. The difference between Vref0 and Vrefn-1 is made smaller when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius. That is, the difference between Vref0 and Vrefn−1, which are outputs from the second voltage control circuit 42c, when the temperature of the liquid crystal display panel 2 is 60 degrees Celsius than when the temperature of the liquid crystal display panel 2 is 30 degrees Celsius. Becomes smaller. As described above, the second voltage control circuit 42c changes the difference between the output voltages Vref0 and Vrefn-1 according to the temperature.

  Accordingly, the source driver drive voltage (AVDD) supplied by the first voltage control circuit 42a is a fixed voltage that does not change according to the temperature, but the Vref0 and Vrefn-1 supplied by the second voltage control circuit 42c. Since the difference is a voltage that changes according to temperature, the voltage is resistance-divided by a circuit composed of n resistors 43a, 43b,... 43n-1, and the source driver drive voltage generation circuit 15 In addition to the source driver drive voltage (AVDD), n kinds of voltages Vref0, Vref1,. These output voltages are supplied to the source driver 4 via a flexible printed circuit board (not shown).

  The source driver 4 generates a voltage corresponding to each gradation using AVDD, n kinds of voltages Vref0, Vref1,... Vrefn-1.

  As described above, the second voltage control circuit 42c of the source driver drive voltage generation circuit 15 shown in FIG. 11 only corrects the difference between Vref0 and Vrefn-1 according to the temperature, so The same effects as those of the source driver drive voltage generation circuit 15 of FIG. 10 can be obtained, such that each voltage can be automatically determined in a balanced manner.

  Furthermore, since the source driver drive voltage generation circuit 15 in FIG. 11 corrects both Vref0 and Vrefn−1 in accordance with the temperature, the dynamic range is increased as compared with the source driver drive voltage generation circuit 15 in FIG. It can also be taken widely.

  The liquid crystal display device and the driving method of the liquid crystal display device according to the present invention have an effect that black display with the minimum luminance can be performed even when the temperature increases, and a liquid crystal display device using OCB mode liquid crystal, and This is useful for a driving method of a liquid crystal display device.

  In addition, the liquid crystal display device and the driving method of the liquid crystal display device according to the present invention have the effect of being able to display the desired luminance even when the temperature changes, and a liquid crystal display device using OCB mode liquid crystal, It is useful for a driving method of a liquid crystal display device.

The block diagram which shows the structure of the liquid crystal display device in the 1st Embodiment of this invention The block diagram which shows the detailed structure of the controller circuit 6 in the 1st Embodiment of this invention The figure which shows an example of the gamma correction table in the 1st Embodiment of this invention The figure which shows an example of the gamma correction table in the case of correct | amending the input display data whose value is below a predetermined value among the input display data in the 1st Embodiment of this invention. The figure which shows the correction method of the input display data in the 1st Embodiment of this invention The block diagram which shows the structure of the liquid crystal display device in the 2nd Embodiment of this invention. The figure which shows the detailed structure of the liquid-crystal drive voltage generation circuit in the 2nd Embodiment of this invention. The figure which shows the relationship between the gradation of the input display data in the 2nd Embodiment of this invention, the output voltage of the source driver 4, and the drive voltage (AVDD) for source drivers. The figure which shows an example of a structure of the drive voltage generation circuit 15 for source drivers in the 2nd Embodiment of this invention. The figure which shows another example of the structure of the drive voltage generation circuit 15 for source drivers in the 2nd Embodiment of this invention from the above. The figure which shows another example of a structure of the drive voltage generation circuit 15 for source drivers in the 2nd Embodiment of this invention. (A) Schematic sectional view of voltage application state (white display state) of liquid crystal display device using conventional OCB mode (b) Voltage application state (black display state) of liquid crystal display device using conventional OCB mode (C) Schematic cross-sectional view of a conventional liquid crystal display device using the OCB mode when no voltage is applied The figure which shows the relationship between the voltage of a OCB mode liquid crystal display device, and a brightness | luminance. The figure which shows the relationship between the gradation of the vicinity where the brightness | luminance of OCB mode liquid crystal display device becomes the minimum, and a brightness | luminance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal display panel 3 Gate driver 4 Source driver 5 Liquid crystal drive voltage generation circuit 6 Controller circuit 7 Temperature detection means 8 Input power supply 9 Display data generation means 10 Image signal processing circuit 11 Timing control circuit 12 Liquid crystal display device 13 Liquid crystal display Drive voltage generation circuit 14 Controller circuit 15 Source driver drive voltage generation circuit 16 Gate driver drive voltage generation circuit 17 Counter signal voltage generation circuit

Claims (9)

A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A source driver for supplying a source signal to the source signal line;
Temperature detecting means for detecting the temperature;
A liquid crystal display device comprising: a source driver driving unit that supplies a source driver driving voltage corresponding to the detected temperature to the source driver. A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A source driver for supplying a source signal to the source signal line;
Temperature detecting means for detecting the temperature;
Correction means for correcting display data for generating the source signal to display data corresponding to the detected temperature;
The liquid crystal display device, wherein the source signal is generated based on the corrected display data.   The liquid crystal display device according to claim 2, wherein the correction means correcting the display data is to perform gamma correction according to the detected temperature. When the correction means corrects the display data, the value of the display data whose value is 0 in the display data is corrected to a first value that is a value corresponding to the detected temperature,
Of the display data, the second value, which is the value of the display data whose signal level is other than 0, is set from the third value to the first value with the maximum value of the display data as the third value. The liquid crystal display device according to claim 2, wherein the first value is corrected to a value obtained by multiplying the value obtained by subtracting the value by the third value and the second value multiplied by the second value.   The liquid crystal display device according to claim 2, wherein the correction means correcting the display data is correcting the display data whose value is equal to or less than a predetermined value in the display data.   The liquid crystal display device according to claim 1, wherein the liquid crystal display element is a liquid crystal display element using OCB mode liquid crystal. A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A liquid crystal display device driving method for driving a liquid crystal display device comprising a source driver for supplying a source signal to the source signal line,
A temperature detection step for detecting the temperature;
And a source driver driving step of supplying a source driver driving voltage corresponding to the detected temperature to the source driver. A liquid crystal display panel having a source signal line and a gate signal line arranged in a matrix, and a liquid crystal display element provided at an intersection of the source signal line and the gate signal line;
A gate driver for supplying a gate signal to the gate signal line;
A liquid crystal display device driving method for driving a liquid crystal display device comprising a source driver for supplying a source signal to the source signal line,
A temperature detection step for detecting the temperature;
A correction step of correcting display data for generating the source signal into display data corresponding to the detected temperature,
The method of driving a liquid crystal display device, wherein the source signal is generated based on the corrected display data. The method for driving a liquid crystal display device according to claim 7, wherein the liquid crystal display element is a liquid crystal display element using OCB mode liquid crystal.

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