JP2004348122A - Liquid crystal display panel driving device and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal panel driving device capable of inexpensively and precisely performing DC-free AC driving of a liquid crystal display panel and a liquid crystal display using the same. <P>SOLUTION: The liquid crystal panel driving device has a reference voltage generating unit provided with a serial unit including a plurality of resistors connected in series, a first switch for supplying a first potential in a first mode and a second potential in a second mode to a terminal of the serial unit and a second switch for supplying the second potential in the first mode and the first potential in the second mode to the other terminal of the serial unit for outputting voltages from connection points between the plurality of resistors and a driving unit for selectively outputting any one of the plurality of voltages according to a value of image data for applying the voltage to a terminal of a pixel of a liquid crystal display panel. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display panel driving device and a liquid crystal display device using the same.

In recent years, a liquid crystal display panel driving device that inputs digital image data, converts the digital image data into analog image data according to a plurality of reference voltage values, and displays an image on a liquid crystal display panel, and a liquid crystal display device using the same have been developed. Spreading in the market.
A conventional liquid crystal display panel driving device and a liquid crystal display device using the same will be described with reference to FIGS. FIG. 5 is a diagram showing a configuration of a conventional digital input liquid crystal display device. In FIG. 5, reference numeral 501 denotes a gate driver for generating vertical writing timing and the like on the panel; 502, a liquid crystal display panel (LCD panel) including thin film transistors and the like; 503, writing of horizontal image data to the panel. The source driver to do.

  The operation of the thus configured digital input liquid crystal display device will be described below. In the source driver 503, a plurality of reference voltage values (in this example, (n + 1) points) (n is an arbitrary positive integer) from the ground potential to the power supply potential E0 together with the digital image data (6 bits each for RGB in this example). Has been given. The D / A converter in the source driver converts the image data input as a digital value into a corresponding analog voltage value according to a polygonal line approximated by a reference voltage value (in this example, Vref (0) to Vref (n)). Is output. In the gate driver 501, a timing signal to be written to a thin film transistor or the like of the liquid crystal display panel 502 is generated. According to this signal, analog image data from the source driver 503 is written to the liquid crystal display panel.

  The liquid crystal display panel is normally operated by AC drive, and is configured to invert and use the voltage applied to the panel every one horizontal scanning period and every one vertical scanning period. As the simplest method of inverting the voltage applied to the panel, Japanese Patent Application Laid-Open No. 07-219482 discloses a method of directly inverting digital data input to the panel.

  FIG. 6 is a diagram showing output voltage values of the source driver when digital image data input to the source driver 503 is directly inverted and when digital image data is not inverted. In FIG. 6, the horizontal axis represents digital data, and the vertical axis represents voltage values. As shown in FIG. 6, when the digital image data itself is inverted, the inverted digital data-output voltage value conversion characteristic is obtained by folding the non-inverted digital data-output voltage value conversion characteristic at the center value of the digital data. It is a broken line (a line that is folded right and left at the center of the horizontal axis). Focusing on the output voltage at each digital value, the non-inverted digital data-output voltage value conversion characteristic and the inverted digital data-output voltage value conversion characteristic are vertically shifted with respect to the midpoint E0 / 2 in the voltage direction. It is not a symmetrical polygonal line (it deviates from the ideal curve in the figure). Therefore, the driving of the liquid crystal display panel has not been completely DC-free AC driving.

  If a DC component is included in the voltage applied to the liquid crystal display panel, the performance may be degraded and the product life may be shortened. A set of a plurality of reference voltages Vref (k) (k = 0 to n) approximated by broken lines has a value such that a DC component is not included in the voltage applied to the liquid crystal display panel on various screens on average. Set was set.

  On the other hand, the digital data-output voltage value conversion characteristic, which is a so-called gamma curve, greatly affects the visual impression given to the user by the display screen of the liquid crystal display panel. However, under the constraint that a set of a plurality of reference voltages Vref (k) (k = 0 to n) is set so that a DC component is not included in the voltage applied to the liquid crystal display panel, the digital data-output voltage value There has been a problem that the conversion characteristic cannot be freely set to a characteristic that gives the user the most desirable visual impression.

A recent digital input liquid crystal display panel inputs a plurality of reference voltage values to an internal D / A converter, and performs D / A conversion of digital data with a conversion characteristic of a polygonal line approximation formed by the reference voltage values. There is a configuration in which analog data after D / A conversion is inverted by inverting the reference voltage value.
FIG. 7 is a diagram showing broken line characteristics at the time of inversion and non-inversion when the reference voltage Vref (k) (k = 0 to n) is inverted in such a liquid crystal display panel. In FIG. 7, the horizontal axis represents digital data, and the vertical axis represents voltage values. In this case, since the voltage of Vref (n) (n = 0 to 10) is inverted, the waveform is inverted in the voltage direction, and almost ideal inverted and non-inverted waveforms are obtained.

  FIG. 8 is a circuit diagram of a commonly used reference voltage generator having such a function of inverting the reference voltage. In FIG. 8, R100 to R10n and R200 to R20n are resistance groups, one of which is connected to the power supply side and the other is connected to the ground side so that they have opposite polarities. The respective resistance values are R100 = R200, R101 = R201,..., R10n = R20n. The selectors 0 to n are selector switches, and switch between a voltage value divided by resistors R100 to R10n and a voltage value divided by resistors R200 to R20n for each horizontal scanning period. With the above configuration, the reference voltage generating section of the conventional example is configured. The output terminals Vref (0) to Vref (n) output the voltage corresponding to the break point at the time of non-inversion and the voltage corresponding to the break point at the time of inversion shown in FIG. Is done.

JP-A-07-219482

In the reference voltage generator of the conventional example shown in FIG. 8, symmetrical voltage values can be obtained at the time of inversion and at the time of non-inversion. However, in the configuration, two groups of resistors for providing voltage values are required, and selector switches are also provided. As many as the number of voltage values are required, the circuit scale is increased.
An object of the present invention is to provide a circuit capable of inverting a reference voltage without increasing the circuit scale, and to provide a liquid crystal display panel driving device capable of driving a digital input liquid crystal display panel at low cost and a liquid crystal display device using the same. I do.

  In order to solve the above problems, the present invention has the following configurations. According to the first aspect of the present invention, in a first mode, a first potential is supplied to one end of the series body in which a plurality of resistors are connected in series, and the first potential is supplied in a second mode. A first switch for supplying a second potential which is a lower potential, and a second switch for supplying the second potential in the first mode to the other end of the series body, and supplying the first potential in the second mode. A second switch for supplying, a reference voltage generating unit that outputs respective voltages from a connection point of the plurality of resistors, video data, and a plurality of voltages output by the reference voltage generating unit. Any one of the plurality of voltages and a plurality of voltages generated by resistance division from the plurality of voltages in accordance with the value of the video data to input and apply to one end of the pixel of the liquid crystal display panel. And a driver for selecting and outputting one A liquid crystal display panel driving device according to claim Rukoto.

The present invention has an effect that an inexpensive liquid crystal display panel driving device that inverts the reference voltage value accurately with a small circuit scale can be realized.
ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display panel drive device which makes DC voltage component applied to a liquid crystal display panel zero with high precision substantially can be implement | achieved.

  According to a second aspect of the present invention, in the first mode, a first potential is supplied to one end of the series body in which a plurality of resistors are connected in series, and the first potential is supplied in a second mode. A first switch for supplying a second potential which is a lower potential, and a second switch for supplying the second potential in the first mode to the other end of the series body, and supplying the first potential in the second mode. A second switch for supplying, a reference voltage generating unit that outputs respective voltages from a connection point of the plurality of resistors, video data, and a plurality of voltages output by the reference voltage generating unit. Any one of the plurality of voltages and a plurality of voltages generated by resistance division from the plurality of voltages in accordance with the value of the video data to input and apply to one end of the pixel of the liquid crystal display panel. One of which is output and the liquid crystal display A liquid crystal display panel driving device, comprising: a driving unit that outputs a voltage at a midpoint between the first potential and the second potential in order to apply the voltage to the other end of the pixel of the panel. .

The present invention has an effect that an inexpensive liquid crystal display panel driving device that inverts the reference voltage value accurately with a small circuit scale can be realized.
ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display panel drive device which makes DC voltage component applied to a liquid crystal display panel zero with high precision substantially can be implement | achieved.

  According to a third aspect of the present invention, in a first mode, a first potential is supplied to one end of the series body in which a plurality of resistors are connected in series, and the first potential is supplied in a second mode. A first switch for supplying a second potential which is a lower potential, and a second switch for supplying the second potential in the first mode to the other end of the series body, and supplying the first potential in the second mode. A second switch for supplying, a reference voltage generating unit that outputs respective voltages from a connection point of the plurality of resistors, video data, and a plurality of voltages output by the reference voltage generating unit. Any one of the plurality of voltages and a plurality of voltages generated by resistance division from the plurality of voltages in accordance with the value of the video data to input and apply to one end of the pixel of the liquid crystal display panel. One of which is output and the liquid crystal display And a driver for outputting the first potential in a first mode and outputting the second potential in a second mode, for applying to the other end of the pixel of the panel. This is a liquid crystal display panel driving device.

The present invention has an effect that an inexpensive liquid crystal display panel driving device that inverts the reference voltage value accurately with a small circuit scale can be realized.
ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display panel drive device which makes DC voltage component applied to a liquid crystal display panel zero with high precision substantially can be implement | achieved.

The liquid crystal display panel according to any one of claims 1 to 3, wherein at least two of the plurality of resistors have different resistance values. It is a driving device.
According to the present invention, it is possible to realize a liquid crystal display panel driving apparatus that displays an image having a predetermined gamma characteristic while maintaining a DC voltage component applied to the liquid crystal display panel at substantially zero with high accuracy.

The invention according to claim 5, wherein at least two resistors among the plurality of resistors have different resistance values, and the first potential and the plurality of voltages are generated from a plurality of voltages generated by dividing the plurality of voltages by resistance. 3. The liquid crystal display panel driving device according to claim 2, wherein a voltage obtained by subtracting a voltage at a middle point from the second potential is a pair of voltages having substantially the same value and different polarities. It is.
A liquid crystal display panel driving device that displays an image with a predetermined gamma characteristic while maintaining the DC voltage component applied to the liquid crystal display panel at substantially zero with high accuracy can be realized.

The invention according to claim 6, wherein the first switch and the second switch are a PNP bipolar transistor or a P-channel MOS transistor connecting the first potential and the series member, and the second potential. 4. The liquid crystal display panel driving device according to claim 1, further comprising an NPN bipolar transistor or an N-channel MOS transistor that connects the transistor and the series body. 5.
The present invention has an effect of realizing an inexpensive liquid crystal display panel driving device capable of inverting a reference voltage value with a small circuit scale.

The invention according to claim 7 is characterized in that, in one pixel, the first mode and the second mode alternate every vertical synchronization period of video data. A liquid crystal display panel driving device according to any one of claims.
According to the present invention, a liquid crystal display panel that makes a DC voltage component applied to the liquid crystal display panel substantially zero with high accuracy without using a screen flicker by using a switching timing signal for vertical scanning of a screen. A driving device can be realized.

The invention according to claim 8 is the liquid crystal display panel driving device according to claim 7, wherein the first mode and the second mode alternate every horizontal synchronization period of video data. .
According to the present invention, a liquid crystal display that makes a DC voltage component applied to a liquid crystal display panel substantially zero with higher accuracy without using a screen flicker by using a switching timing signal for horizontal scanning of a screen. A panel driving device can be realized. According to the present invention, flicker on the screen can be eliminated.

9. The liquid crystal display panel according to claim 7, wherein the first mode and the second mode are alternated for each pixel of video data. It is a driving device.
According to the present invention, it is possible to realize a liquid crystal display panel driving device that makes the DC voltage component applied to the liquid crystal display panel substantially zero with higher accuracy without causing flicker on the screen.

According to a tenth aspect of the present invention, the first potential is a power supply potential and the second potential is a ground potential. Liquid crystal display panel driving device.
According to the present invention, a liquid crystal display panel driving device can be easily realized with a small circuit scale by using a power supply voltage and a ground potential used for driving a liquid crystal display panel as a high potential and a low potential, respectively.

  The invention according to claim 11, wherein the reference voltage generating section has a plurality of sets of series bodies in which a plurality of resistors are connected in series, and the first switch has a plurality of sets of the series bodies in response to an external command. A first potential is supplied to one end of the series member selected from the first mode in a first mode, and a second potential that is lower than the first potential is supplied in a second mode. The second switch supplies the second potential to the other end of the selected series body in the first mode, supplies the first potential in the second mode, and supplies the second potential to the other end of the selected series body. 4. The liquid crystal display panel driving device according to claim 1, wherein each voltage is output from a connection point of the plurality of resistors. 5.

  According to the present invention, a digital data-output voltage value conversion characteristic, which is a so-called gamma curve, can be arbitrarily selected from among a plurality of characteristics while a DC voltage component applied to a liquid crystal display panel is maintained at substantially zero with high accuracy. A liquid crystal display panel drive device that can be set is realized.

A twelfth aspect of the present invention is a liquid crystal display device comprising the liquid crystal display panel driving device according to any one of the first to third aspects, and a liquid crystal display panel.
The present invention has an effect that an inexpensive liquid crystal display device that inverts a reference voltage value with a small circuit scale can be realized by using the liquid crystal display panel driving device of the present invention.
According to the present invention, it is possible to realize a liquid crystal display device that makes the DC voltage component applied to the liquid crystal display panel substantially zero with high accuracy.

  ADVANTAGE OF THE INVENTION According to the present invention, a liquid crystal display panel drive that generates a non-inverted and inverted reference voltage that does not generate a DC component with high accuracy with a small circuit scale and that can inexpensively and accurately drive a liquid crystal display panel with DC-free AC driving. An advantageous effect is obtained that a device and a liquid crystal display device using the same can be realized.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments that specifically show the best mode for carrying out the present invention will be described below with reference to the drawings.

<< Embodiment 1 >>
The liquid crystal display panel driving device and the liquid crystal display device according to the first embodiment will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a configuration of the liquid crystal display device according to the first embodiment. Reference numeral 101 denotes a liquid crystal drive synchronization signal generating unit, 102 denotes a horizontal / vertical complementing unit, 103 denotes a color signal processing unit, 104 denotes a liquid crystal display panel driving device, and 105 denotes a liquid crystal display panel. The liquid crystal display panel driving device 104 includes a reference voltage generator 111, a source driver 112, and a gate driver 113.

The liquid crystal drive synchronization signal generator 101 includes D flip-flop circuits 121 and 122, an exclusive OR operation circuit 123, and an inverter 124. The D flip-flop circuit 121 receives the horizontal synchronizing signal and alternately outputs High and Low. The D flip-flop circuit 122 receives a vertical synchronizing signal and alternately outputs High and Low.
The exclusive OR operation circuit 123 receives the output signal of the D flip-flop circuit 121 and the output signal of the D flip-flop circuit 122, outputs High if they are different, and outputs Low if they match. The inverter 124 inverts the input signal and outputs the inverted signal.
The signal output from the exclusive OR operation circuit 123 is supplied to the reference voltage generator 111. The horizontal synchronization signal, the vertical synchronization signal, and the signal output from the inverter 124 are supplied to the gate driver 113. The liquid crystal drive synchronization signal generator 101 outputs a liquid crystal drive synchronization signal that is inverted every horizontal line and inverted every vertical synchronization period for each horizontal line. The liquid crystal display panel driving device 104 enters the first mode when the liquid crystal driving synchronization signal is high, and enters the second mode when the liquid crystal driving synchronization signal is low. The first mode and the second mode may be alternated only every vertical synchronization signal period of video data.

The horizontal / vertical complement unit 102 inputs video data and complements the number of video data so as to match the number of pixels of the liquid crystal display panel 105 in each of the horizontal and vertical directions.
The color signal processing unit 103 performs adjustment of RGB contrast, white balance, and the like.

  The reference voltage generator 111 includes a first switch 131, a second switch 132, and resistors R133 (0) to R133 (n) (n is an arbitrary positive integer of 2 or more). The first switch 131 switches the voltage supplied to the resistor R133 (0), which is one end of the resistor group, to either the power supply potential E0 or the ground potential. The second switch 132 switches the voltage supplied to the resistor R133 (n), which is the other end of the resistor group, to either the power supply potential E0 or the ground potential.

In the first mode, the first switch 131 and the second switch 132 are connected to the solid line. The first switch 131 supplies the power supply potential E0 to the resistor R133 (0), and the second switch 132 supplies the ground potential to the resistor 133 (n) (non-inversion of the reference voltage). In the second mode, the first switch 131 and the second switch 132 are connected on the broken line side. The first switch 131 supplies the ground potential to the resistor R133 (0), and the second switch 132 supplies the power supply potential E0 to the resistor 133 (n) (inversion of the reference voltage).
The resistors R133 (0) to R133 (n) determine the reference voltages Vref (0) to Vref (n). The voltages Vref (0) to Vref (n) divided by the resistors R133 (0) to R133 (n) are supplied to the pixel driver 142 of the source driver 112.

The source driver 112 has a shift register 141 and a pixel driver 142. The shift register 141 receives the 6-bit RGB serial digital data output from the color signal processing unit 103, converts the data into parallel signals, and outputs the parallel signals.
The pixel driver 142 has three (RGB) sub-pixel driving units 151 of the number of pixels in the horizontal direction of the liquid crystal display panel 105. The sub-pixel driving unit 151 includes input units 161 (0) to 161 (n), resistors R162 (0) to R162 (m) (any positive integer where m> n), and switches 163 (0) to 163 (m). , 6-bit data decoder 164. The input units 161 (0) to 161 (n) receive the voltages Vref (0) to Vref (n) output from the reference voltage generator 111, respectively.

  The 6-bit data decoder 164 receives the digital signal output from the shift register 141, turns on one of the switches 163 (0) to (m) based on the value of the digital signal, and turns on the other switches. Turn off. The voltage divided by the resistors R162 (0) to R162 (m) passes through the turned-on switch and is applied to one end of the pixel of the liquid crystal display panel 105. The voltage at this time is the value shown in FIG.

  Counting from the middle point to the end of the series body of the resistors R133 (0) to R133 (n), the same number of resistors on both sides are the same, and the resistance value gradually decreases from the middle point to the end. Become. Therefore, the voltage obtained by subtracting the voltage E0 / 2 of 1/2 of the power supply potential from the divided voltages Vref (0) to Vref (n) generated by the resistors R133 (0) to R133 (n) is substantially the same. It consists of a pair of voltages of different values and different polarities.

  FIG. 2 is a diagram illustrating voltage values output by the sub-pixel driving unit 151 of the source driver 112 in the first mode (when the reference voltage is not inverted) and in the second mode (when the reference voltage is inverted). In FIG. 2, the horizontal axis represents digital data, and the vertical axis represents voltage values. Reference numeral 201 denotes a polygonal line indicating the conversion characteristic of the first mode (non-inversion), and reference numeral 202 denotes a polygonal line indicating the conversion characteristic of the second mode (at the time of inversion). The non-inverted digital data-output voltage value conversion characteristics and the inverted digital data-output voltage value conversion characteristics are polygonal lines that are vertically symmetric with respect to the midpoint E0 / 2 in the voltage direction (almost ideal). A curve is obtained.) Therefore, driving of the liquid crystal display panel is completely DC-free AC driving.

  The sub-pixel driving unit 151 inputs digital image data, and outputs resistors R133 (0) to R133 (n) (n is an arbitrary positive integer) and resistors R162 (0) to R162 (m) (m is an arbitrary number). A corresponding analog voltage value is output according to a polygonal line 201 (first mode) or a polygonal line 202 (second mode) approximated by voltage values divided by a positive integer.

To the other end of the pixel of the liquid crystal display panel 105, a voltage (E0 / 2) at a midpoint between the power supply potential E0 and the ground potential 0V is applied.
The gate driver 113 receives the horizontal synchronizing signal, the vertical synchronizing signal, and the signal output from the inverter 124 of the liquid crystal driving synchronizing signal generator 101, and outputs a write timing signal.
The liquid crystal display panel 105 displays analog image data output by the source driver 112 in synchronization with a timing signal output by the gate driver 113.

The operation of the liquid crystal display panel driving device and the liquid crystal display device according to the first embodiment of the present invention configured as described above will be described.
In the first mode, the reference voltage generator 111 connects the first switch 131 and the second switch 132 to the solid line side, supplies the power supply potential E0 to the resistor R133 (0), and connects the ground potential to the resistor 133 ( n). At this time, the reference voltage generator 111 outputs voltage values Vref (0) to Vref (n) corresponding to the break points at the time of non-inversion 201 in FIG.

  On the other hand, in the second mode, the first switch 131 and the second switch 132 are connected to the broken line, the ground potential is supplied to the resistor R133 (0), and the power supply potential E0 is supplied to the resistor 133 (n). . At this time, the reference voltage generator 111 outputs voltage values Vref (0) to Vref (n) corresponding to the break points at the time of inversion 202 in FIG.

As a result, non-inverted and inverted reference voltage values are obtained for Vref (0) to Vref (n) every time the first switch 131 and the second switch 132 are switched. According to the liquid crystal display panel driving device and the liquid crystal display device of the first embodiment of the present invention, the reference voltage at the time of non-inversion and at the time of inversion shown in FIG. Can be driven.
In the first embodiment, in order to correspond to FIG. 2, the configuration is such that the resistance value is symmetrical from the middle point of the series body of the resistors R133 (0) to R133 (n). It is not limited to such a method of obtaining the resistance value.

<< Embodiment 2 >>
The liquid crystal display panel driving device and the liquid crystal display device according to the second embodiment will be described with reference to FIGS. FIG. 3 is a block diagram illustrating a configuration of the liquid crystal display device according to the second embodiment. The liquid crystal display panel driving device and the liquid crystal display device according to the second embodiment are different from the first embodiment in a reference voltage generator 301 and a switch 302. The other configuration is the same as that of the first embodiment, and thus the same reference numerals are given and the detailed description is omitted.

  The reference voltage generator 301 will be described. The difference between the reference voltage generation unit 301 of the second embodiment and the reference voltage generation unit 111 of the first embodiment is that the series connection of the resistors R133 (0) to R133 (n) includes the resistors R133 (0) to R133 (0). The resistance value gradually decreases toward (n). In FIG. 3, the first switch 131 and the second switch 132 are represented by PNP bipolar transistors TR1 and TR3 and NPN bipolar transistors TR2 and TR4 that specifically constitute the switches.

  The PNP bipolar transistor TR1 and the NPN bipolar transistor TR2 switch the voltage supplied to the resistor R133 (0), which is one end of the resistor group, to the power supply potential E0 in the first mode and to the ground potential in the second mode. The PNP bipolar transistor TR3 and the NPN bipolar transistor TR4 switch the voltage supplied to the resistor R133 (n), which is the other end of the resistor group, to the ground potential in the first mode and to the power supply potential E0 in the second mode. TR1 and TR4 are controlled by the same control signal, and TR2 and TR3 are also controlled by the same control signal, and each is configured to open and close in opposite phases.

In the liquid crystal display panel driving device and the liquid crystal display device of the second embodiment, the voltage applied to the other end of the pixel of the liquid crystal display panel 105 is different from that of the first embodiment. In the liquid crystal display panel driving device of the first embodiment, the voltage E0 / 2 at the midpoint between the first potential and the second potential is applied to the other end of the pixel of the liquid crystal display panel 105. In the liquid crystal display panel driving device according to the second embodiment, the gate driver 113 controls the switch 302 to apply the power supply potential E0 to the other end of the pixel of the liquid crystal display panel 105 in the first mode. In the mode, the ground potential is applied.
In the second embodiment, the first mode and the second mode alternate for each horizontal line of video data and alternate for each horizontal line in a vertical synchronization period. The first mode and the second mode may be alternated only every vertical synchronization signal period of video data.

  The operation of the liquid crystal display panel driving device and the liquid crystal display device according to the second embodiment of the present invention configured as described above will be described with reference to FIG. FIG. 7 is a diagram illustrating voltage values output by the sub-pixel driving unit 151 of the source driver 112 in the first mode (when not inverting) and the second mode (when inverting) in the second embodiment. In FIG. 7, the horizontal axis represents digital data, and the vertical axis represents voltage values. FIG. 7 is the same as the conventional example. The non-inverted digital data-output voltage value conversion characteristics and the inverted digital data-output voltage value conversion characteristics are polygonal lines that are vertically symmetric with respect to the midpoint E0 / 2 in the voltage direction (almost ideal). A curve is obtained.) Therefore, driving of the liquid crystal display panel is completely DC-free AC driving.

In the first mode, the reference voltage generator 301 turns on TR1 and TR4 and turns off TR2 and TR3. At this time, the resistor R133 (0) side is connected to the power supply side, and the resistor R133 (n) side is connected to the ground side. To Vref (n) are output.
On the other hand, in the second mode, the reference voltage generator 301 turns on TR2 and TR3 and turns off TR1 and TR4. At this time, the resistor R133 (0) side is connected to the ground side, and the resistor R133 (n) side is connected to the power supply side, and the voltage values Vref (0) to Vref (0) corresponding to the break point at the time of inversion 702 in FIG. Vref (n) is output.

  The first mode and the second mode alternate every vertical synchronization signal period and every horizontal synchronization period of video data. As a result, non-inverted and inverted reference voltage values are obtained for Vref (0) to Vref (n) each time TR1 and TR4 and TR2 and TR3 are opened and closed. According to the liquid crystal display panel driving device and the liquid crystal display device of the second embodiment of the present invention, the reference voltage at the time of non-inversion and at the time of inversion shown in FIG. Can be driven.

Note that the same effect can be obtained even if reference voltage generating section 301 of the second embodiment has a P-channel MOS transistor instead of a PNP bipolar transistor and an N-channel MOS transistor instead of an NPN bipolar transistor.
In the second embodiment, in order to correspond to FIG. 7, the resistance value is gradually reduced from the resistance R133 (0) to the resistance 133 (n). However, the present invention is not necessarily limited to such a resistance. It is not limited to the value taking.

<< Embodiment 3 >>
The liquid crystal display panel driving device and the liquid crystal display device according to the third embodiment will be described with reference to FIG. The liquid crystal display panel driving device and the liquid crystal display device according to the third embodiment are different from the first embodiment in that a reference voltage generating unit 401 is provided instead of the reference voltage generating unit 111. The other configuration is the same as that of the first embodiment, and a detailed description will be omitted.

  The reference voltage generator 401 will be described. FIG. 4 is a block diagram illustrating a configuration of the reference voltage generation unit 401 of the liquid crystal display device according to the third embodiment. The reference voltage generator 401 includes a first reference voltage generator 411, a second reference voltage generator 412, a third reference voltage generator 413, a fourth reference voltage generator 414, and n four changeover switches 415. (0) to (n). The first reference voltage generator 411 has a resistor series body (n is a positive integer of 2 or more) of resistors R133 (0) to R133 (n), and switches 131 and 132. The first reference voltage generator 411 has the same configuration as the reference voltage generator 301 of the first embodiment, and a detailed description is omitted. The second reference voltage generation section 412 has a resistor series body of resistors R423 (0) to R423 (n). The third reference voltage generator 413 has a resistor series body of resistors R433 (0) to R433 (n). The fourth reference voltage generation section 414 has a resistor series body of resistors R443 (0) to R443 (n). Both ends of each resistor series body of the first to fourth reference voltage generators 414 are connected to switching output terminals of the switches 131 and 132. Each series resistor of the first to fourth reference voltage generators 414 has a different gamma characteristic.

  The user selects an arbitrary gamma characteristic from the four gamma characteristics on an operation panel (not shown) of the liquid crystal display device. The operation panel outputs a 2-bit gamma characteristic selection signal 406. The n four changeover switches 415 (0) to 415 (n) receive the reference voltages output from the first to fourth reference voltage generators 411 to 414, respectively, and receive the first to fourth reference voltages in response to the gamma characteristic selection signal 406. The reference voltages Vref (0) to Vref (n) output from the reference voltage generators selected from the four reference voltage generators 411 to 414 are output.

The liquid crystal display device according to the third embodiment can display an image having an arbitrary gamma characteristic preferred by the user.
The reference voltage generation section 401 of the third embodiment is changed to a resistance configuration similar to that of the reference voltage generation section 301 of the second embodiment and having a plurality of (for example, four) resistance series bodies having different gamma characteristics. Thus, the present invention can be applied to the liquid crystal display panel driving device and the liquid crystal display device of the second embodiment.
In the first to third embodiments, the first mode and the second mode may be alternated for each vertical synchronization signal period of video data and for each pixel. The first mode and the second mode may be alternated for each horizontal synchronization signal period of video data and for each pixel. The first mode and the second mode may be alternated for each vertical synchronization signal period of video data, for each horizontal synchronization signal period, and for each pixel.

  The present invention is useful for a liquid crystal display panel driving device and a liquid crystal display device.

FIG. 1 is a block diagram illustrating a configuration of a liquid crystal display device according to Embodiment 1 of the present invention. FIG. 7 is a diagram showing output voltage values of the source driver when the reference voltage is inverted and when the reference voltage is not inverted according to the first embodiment of the present invention; FIG. 4 is a block diagram illustrating a configuration of a liquid crystal display device according to a second embodiment of the present invention. FIG. 9 is a block diagram showing a configuration of a reference voltage generator of a liquid crystal display device according to a third embodiment of the present invention. Diagram showing the configuration of a conventional digital input liquid crystal display device The figure which shows the output voltage value of the source driver at the time of inversion and non-inversion of digital image data FIG. 10 is a diagram illustrating output voltage values of a source driver when a reference voltage is inverted and non-inverted according to a second embodiment of the present invention and a conventional example. Circuit diagram of conventional reference voltage generator

Explanation of reference numerals

Reference Signs List 101 Synchronous signal generation unit for liquid crystal drive 102 Horizontal / vertical complement unit 103 Color signal processing unit 104 Liquid crystal display panel driving device 105 Liquid crystal display panel 111, 301 Reference voltage generation unit 112 Source driver 113 Gate driver 121, 122 D flip-flop circuit 123 Exclusive OR operation circuit 124 Inverter 131, 132, 163 (0) to 163 (m), 302 Switch R133 (0) to R133 (n), R162 (0) to R162 (m) Resistance 141 Shift register 142 Pixel Driver 151 Sub-pixel driver 161 Input 164 6-bit data decoder

Claims (12)

A series body in which a plurality of resistors are connected in series, and a second potential which is lower than the first potential in the second mode by supplying a first potential to one end of the series body in a first mode. And a second switch that supplies the second potential to the other end of the series body in a first mode and supplies the first potential in a second mode. A reference voltage generator that outputs each voltage from a connection point of the plurality of resistors;
The video data and the plurality of voltages output by the reference voltage generator are input and applied to one end of a pixel of a liquid crystal display panel, in accordance with the value of the video data, the plurality of voltages, and A drive unit that selects and outputs one of a plurality of voltages generated by resistance division from the plurality of voltages;
A liquid crystal display panel driving device, comprising: A series body in which a plurality of resistors are connected in series, and a second potential which is lower than the first potential in the second mode by supplying a first potential to one end of the series body in a first mode. And a second switch that supplies the second potential to the other end of the series body in a first mode and supplies the first potential in a second mode. A reference voltage generator that outputs each voltage from a connection point of the plurality of resistors;
The video data and the plurality of voltages output by the reference voltage generator are input and applied to one end of a pixel of a liquid crystal display panel, in accordance with the value of the video data, the plurality of voltages, and Selecting and outputting any one of a plurality of voltages generated by resistance division from a plurality of voltages, and applying the first potential and the second potential to the other end of a pixel of the liquid crystal display panel; A driving unit that outputs a voltage at the midpoint between the potential of the second potential and
A liquid crystal display panel driving device, comprising: A series body in which a plurality of resistors are connected in series, and a second potential which is lower than the first potential in the second mode by supplying a first potential to one end of the series body in a first mode. And a second switch that supplies the second potential to the other end of the series body in a first mode and supplies the first potential in a second mode. A reference voltage generator that outputs each voltage from a connection point of the plurality of resistors;
The video data and the plurality of voltages output by the reference voltage generator are input and applied to one end of a pixel of a liquid crystal display panel, in accordance with the value of the video data, the plurality of voltages, and In order to select and output any one of a plurality of voltages generated by resistance division from a plurality of voltages, and to apply the selected voltage to the other end of the pixel of the liquid crystal display panel, the first mode is used. A driving unit that outputs the second potential in the second mode,
A liquid crystal display panel driving device, comprising:   4. The liquid crystal display panel driving device according to claim 1, wherein at least two resistors among the plurality of resistors have different resistance values. 5. At least two resistors of the plurality of resistors have different resistance values;
A voltage obtained by subtracting a voltage at a middle point between the first potential and the second potential from a plurality of voltages generated by resistance division from the plurality of voltages has substantially the same value and voltages of different polarities. Composed of pairs,
The liquid crystal display panel driving device according to claim 2, wherein:   The first switch and the second switch are a PNP bipolar transistor or a P-channel MOS transistor connecting the first potential and the series body, and an NPN connecting the second potential and the series body. 4. The liquid crystal display panel driving device according to claim 1, further comprising a bipolar transistor or an N-channel MOS transistor.   4. The liquid crystal according to claim 1, wherein, in one pixel, the first mode and the second mode alternate every vertical synchronization period of video data. 5. Display panel drive.   8. The liquid crystal display panel driving device according to claim 7, wherein the first mode and the second mode alternate every horizontal synchronization period of video data.   9. The liquid crystal display panel driving device according to claim 7, wherein the first mode and the second mode alternate for each pixel of video data.   4. The liquid crystal display panel driving device according to claim 1, wherein the first potential is a power supply potential, and the second potential is a ground potential. 5. The reference voltage generation unit has a plurality of series bodies in which a plurality of resistors are connected in series,
The first switch supplies a first potential in a first mode to one end of the series body selected from a plurality of sets of the series bodies in response to an external command, and supplies the first potential in a second mode. Supplying a second potential which is lower than the potential of 1;
The second switch supplies the second potential to the other end of the selected series body in a first mode, and supplies the first potential in a second mode;
Outputting respective voltages from connection points of the plurality of resistors of the selected series body,
4. The liquid crystal display panel driving device according to claim 1, wherein:   A liquid crystal display device comprising: the liquid crystal display panel driving device according to claim 1; and a liquid crystal display panel.

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