JP2009187035A - Source driver, electro-optical device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a source driver that achieves precharging of source lines by precharge voltages settable with high accuracy, to provide an electro-optical device, and to provide an electronic apparatus. <P>SOLUTION: The source driver includes: a first driver block including first to p-th source output blocks arrayed in a first direction, each source output block having an output circuit for driving a source line; a second driver block including (p+1)th to q-th source output blocks arranged in the first direction, each source output block having an output circuit for driving a source line; and first and second precharge lines for supplying first and second precharge voltages for precharging outputs from the output circuits. The first and second precharge voltages are supplied to voltage feeding points of the first and second precharge lines which are formed such that the load up to the p-th source output block end is made equal to the load up to the (p+1)th source output block end. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a source driver, an electro-optical device, and an electronic apparatus.

  For example, in an active matrix type liquid crystal display (hereinafter referred to as LCD) panel (electro-optical device in a broad sense), a source line may be driven by so-called multi-drive. When a demultiplexer is formed on an LCD panel, the source driver that drives the source line supplies the LCD panel with time-division multiplexed gradation voltages corresponding to the gradation data for a plurality of dots constituting one pixel. Then, the gradation voltage corresponding to each source line is separated by the multiplexer. In this case, the number of source outputs of the source driver can be reduced.

  Further, when the demultiplexer is not formed on the LCD panel, the source driver is configured to include the demultiplexer. In this case, the source driver can share the circuit by the number of dots that are time-divided, and the circuit scale can be reduced.

  In such an LCD panel, a precharge technique for increasing the driving speed of liquid crystal is known. In this precharge technique, the source line charge associated with the supply of the drive voltage based on the gradation data is obtained by precharging the source line to a predetermined potential before driving the source line based on the gradation data. The amount of charge / discharge can be reduced.

  This precharge technique is disclosed in Patent Document 1, for example. In Patent Document 1, different DC potentials are prepared in advance, and a switch is provided between each DC potential and the source line. A precharge technique is disclosed in which a connection between a prepared DC potential and a source line is controlled by controlling a switch corresponding to the polarity of inversion driving of liquid crystal. According to this precharge technology, even when the precharge cycle is shortened, the amount of charge and discharge of the source line associated with the drive can be reduced, the liquid crystal drive time is increased, and the increase in power consumption is suppressed. be able to.

Japanese Patent Laid-Open No. 10-11032

  The precharge technique disclosed in Patent Document 1 changes the potential of the source line prior to the driving period in order to shorten the driving period as described above. For this reason, the accuracy of the precharge voltage is not so required.

  However, in recent years, the progress of high definition and multi-gradation of LCD panels has been remarkable. Therefore, when the effective value of the voltage written to the pixel electrode is different, it is possible to clearly discriminate the difference between the pixels displayed in gradation. This effective value corresponds to, for example, an integrated value of the voltage applied to the pixel electrode in one horizontal scanning period. Therefore, even if the pixels are connected to the source line to which the same gradation voltage is supplied, if a difference occurs in the precharge voltage, the difference in gradation display can be determined, resulting in a deterioration in image quality. Turned out to be. In particular, in the multi-drive in which the source line is driven using gradation data for a plurality of pixels, the gradation characteristics cannot be changed for each pixel of a plurality of multiplexed pixels. The resulting degradation in image quality is significant.

  Such a source driver for driving the source line of the LCD panel is divided into, for example, two source driver blocks from the viewpoint of layout efficiency. Each source driver block drives the source line in the display area on the left side of the LCD panel and the source line in the display area on the right side of the LCD panel. Therefore, if there is a difference in precharge voltage between two source driver blocks, the same gradation value is displayed and the boundary line between the left display area and the right display area of the LCD panel is recognized. .

  Since the above problems are caused by the effective value of the voltage applied to the pixel, the present invention is not limited to the source driver that multi-drives the LCD panel, and the same applies to a source driver that performs non-multi-drive. Accordingly, it is desirable that the source driver that precharges the source line prior to driving can set the precharge voltage with high accuracy.

  The present invention has been made in view of the technical problems as described above, and an object of the present invention is to provide a source driver and an electro-optical device that realize precharge of a source line with a precharge voltage that can be set with high accuracy. It is to provide an apparatus and an electronic device.

In order to solve the above problems, the present invention
A source driver for driving a source line of an electro-optical device,
Each source output block includes an output circuit for driving a source line and includes first to p-th (p is an integer of 2 or more) source output blocks arranged in a first direction. When,
Each source output block includes an output circuit for driving a source line and includes (p + 1) th to qth (p + 1 <q, q is an integer) source output blocks arranged in the first direction. Two driver blocks;
A precharge line for supplying a precharge voltage for precharging the output of the output circuit of each source output block of the first and second driver blocks;
The precharge voltage is supplied to the voltage supply point of the precharge line provided so that the load up to the p-th source output block end and the load up to the (p + 1) -th source output block end are equal. Related to the source driver.

  According to the present invention, even if the number p of source output blocks of the first driver block is different from the number of source output blocks (pq) of the second driver block, the output of the pth source output block The precharge voltage of the circuit and the precharge voltage of the output circuit of the (p + 1) th source output block can be made uniform. Therefore, the effective value of the pixel electrode connected to the source line driven by the output circuit of the p-th source output block and the pixel electrode connected to the source line driven by the output circuit of the (p + 1) -th source output block. The effective value can be made uniform, and the difference in the effective value of the voltage applied to the pixel is caused by the difference in the precharge voltage, and the deterioration of the image quality due to this difference can be suppressed.

In the source driver according to the present invention,
Each output circuit
An operational amplifier for driving the source line based on the gradation voltage corresponding to the gradation data;
A first switch element inserted between the precharge line and the output of the operational amplifier;
A second switch element inserted between the precharge line and the input of the operational amplifier;
In the precharge period,
In a state where the first switch element is turned off and the second switch element is turned on, the operational amplifier drives the output of the output circuit with a first current driving capability, and then the first switch element is turned on. With the second switch element turned on, the operational amplifier drives the output of the output circuit with a second current drive capability lower than the first current drive capability, and then the first switch element is turned on, Turn off the second switch element,
In the drive period after the precharge period,
With the first switch element turned off and the second switch element turned off, the operational amplifier can drive the output of the output circuit based on the gradation voltage.

  According to the present invention, the voltage of the source output can be set to the precharge voltage at high speed during the precharge period. In addition, even if the source output voltage is slightly lower than the precharge voltage due to the ON resistance of the first switch element, the second current drive capability can supply charges to the output of the operational amplifier. Precharge voltage can be set with high accuracy. Furthermore, if the second current driving capability is lowered, an increase in current consumption can be suppressed.

The present invention also provides
A source driver for driving a source line of an electro-optical device,
Each source output block includes an output circuit for driving a source line and includes first to p-th (p is an integer of 2 or more) source output blocks arranged in a first direction. When,
Each source output block includes an output circuit for driving a source line and includes (p + 1) th to qth (p + 1 <q, q is an integer) source output blocks arranged in the first direction. Two driver blocks;
A voltage supply line for supplying a given voltage to the output of the output circuit of each source output block of the first and second driver blocks;
The given voltage is applied to a voltage supply point of the voltage supply line provided so that a load to the end of the p-th source output block and a load to the end of the (p + 1) -th source output block are equal. Supplied,
Each output circuit of the first and second driver blocks is
After the given voltage is supplied to a plurality of source lines, the plurality of source lines are driven in a time division manner based on multiplexed gradation data in which gradation data of each dot for a plurality of pixels is multiplexed. Related to the source driver.

  According to the present invention, even if the influence on the effective value of the voltage applied to the pixel of each dot for a plurality of pixels is a multi-drive in which the influence due to the voltage fluctuation of the voltage supply line differs for each dot, the voltage supply By aligning the voltages of the lines, it is possible to uniformly prevent the image quality from deteriorating and to minimize the influence of the voltage error of the voltage supply lines.

In the source driver according to the present invention,
The given voltage is
It may be a precharge voltage.

In the source driver according to the present invention,
Each output circuit
An operational amplifier for driving the source line based on the gradation voltage corresponding to the gradation data;
A first switch element inserted between the voltage supply line and the output of the operational amplifier;
A second switch element inserted between the voltage supply line and the input of the operational amplifier;
In the voltage setting period,
In a state where the first switch element is turned off and the second switch element is turned on, the operational amplifier drives the output of the output circuit with a first current driving capability, and then the first switch element is turned on. With the second switch element turned on, the operational amplifier drives the output of the output circuit with a second current drive capability lower than the first current drive capability, and then the first switch element is turned on, Turn off the second switch element,
In the driving period after the voltage setting period,
With the first switch element turned off and the second switch element turned off, the operational amplifier can drive the output of the output circuit based on the gradation voltage.

  According to the present invention, the source output voltage can be set to a given voltage at high speed in the voltage setting period. In addition, even if the source output voltage is slightly lower than the voltage of the voltage supply line due to the ON resistance of the first switch element, the second current drive capability can supply charges to the output of the operational amplifier. The voltage can be set to the voltage of the voltage supply line with high accuracy. Furthermore, if the second current driving capability is lowered, an increase in current consumption can be suppressed.

In the source driver according to the present invention,
The given voltage is
A voltage of the source line after short-circuiting the plurality of source lines of the electro-optical device;
Each output circuit
With the plurality of source lines set to the voltage of the source line after the short circuit, the source lines can be driven based on the gradation data.

  According to the present invention, the charge once stored in the source line can be reused prior to driving the source line, and the source line can be driven in the drive period, so there is no need to replenish extra charges from the outside. The voltage of the voltage supply line can be set to the source line with high accuracy, and the power consumption can be reduced.

In the source driver according to the present invention,
The given voltage is
A voltage of the source line after short-circuiting the plurality of source lines of the electro-optical device, the pixel electrode connected to the source line through a switch element, and the counter electrode facing through the electro-optical material;
Each output circuit
Each source line of the plurality of source lines can be driven based on grayscale data in a state where a voltage after short-circuiting the plurality of source lines and the counter electrode is set to the plurality of source lines. .

  According to the present invention, prior to driving the source line, the charge once stored in the source line and the counter electrode can be reused to drive the source line during the driving period. Thus, the voltage of the voltage supply line can be set to the source line with high accuracy and the power consumption can be reduced.

The present invention also provides
A source driver for driving a source line of an electro-optical device,
Each source output block includes an output circuit for driving a source line and includes first to p-th (p is an integer of 2 or more) source output blocks arranged in a first direction. When,
Each source output block includes an output circuit for driving a source line and includes (p + 1) th to qth (p + 1 <q, q is an integer) source output blocks arranged in the first direction. Two driver blocks;
First and second precharge lines for supplying first and second precharge voltages for precharging the output of the output circuit of each source output block of the first and second driver blocks;
Each output circuit of the first and second driver blocks is
After supplying one of the first and second precharge voltages to a plurality of source lines all at once, based on multiplexed gradation data in which gradation data of each dot for a plurality of pixels is multiplexed Drive each source line of multiple source lines in a time-sharing manner
The voltage supply point of the first precharge line provided so that the load to the end of the p-th source output block and the load to the end of the (p + 1) -th source output block are equal to each other. As the precharge voltage, the highest potential voltage that each output circuit outputs to the source line is supplied,
The voltage supply point of the second precharge line provided so that the load to the end of the p-th source output block and the load to the end of the (p + 1) -th source output block are equal to each other. This relates to a source driver to which the lowest potential voltage output from each output circuit to the source line is supplied as a precharge voltage.

In the source driver according to the present invention,
Each output circuit
An operational amplifier for driving the source line based on the gradation voltage corresponding to the gradation data;
A first switch element inserted between the first or second precharge line and the output of the operational amplifier;
A second switch element inserted between the first or second precharge line and the input of the operational amplifier;
In the precharge period,
In a state where the first switch element is turned off and the second switch element is turned on, the operational amplifier drives the output of the output circuit with a first current driving capability, and then the first switch element is turned on. With the second switch element turned on, the operational amplifier drives the output of the output circuit with a second current drive capability lower than the first current drive capability, and then the first switch element is turned on, Turn off the second switch element,
In the drive period after the precharge period,
With the first switch element turned off and the second switch element turned off, the operational amplifier can drive the output of the output circuit based on the gradation voltage.

  According to any one of the above-described inventions, for example, by making the precharge voltage different between the positive polarity and the negative polarity in polarity inversion driving, it is not necessary to perform useless precharge, thereby reducing power consumption. And high-speed driving period can be achieved at the same time.

In the source driver according to the present invention,
A multiplexed voltage obtained by time-dividing a plurality of gradation voltages in one horizontal scanning period is input to the input of the operational amplifier,
Each source output block
A demultiplexer for separating the output of the operational amplifier into a plurality of source lines in synchronization with the time division timing of the multiplexed voltage may be included.

  According to the present invention, a configuration in which a demultiplexer is omitted as an electro-optical device can be employed. Therefore, it is possible to use an amorphous silicon liquid crystal panel that can be manufactured at low cost, although only a switch element with low driving capability can be formed in the electro-optical device.

The present invention also provides
Multiple gate lines,
Multiple source lines,
Each pixel is a plurality of pixels specified by each gate line and each source line;
A gate driver that scans the plurality of gate lines;
The present invention relates to an electro-optical device including any one of the source drivers described above that drives the plurality of source lines.

The present invention also provides
Multiple gate lines,
Multiple source lines,
Each pixel is a plurality of pixels specified by each gate line and each source line;
A gate driver that scans the plurality of gate lines;
Any one of the source drivers described above for driving the plurality of source lines;
The present invention relates to an electro-optical device including a demultiplexer that separates one of the outputs of the source driver into a plurality of source lines.

The present invention also provides
The present invention relates to an electro-optical device including the source driver described above.

  According to any one of the above-described inventions, it is possible to provide an electro-optical device that includes a source driver that realizes precharge of a source line with a precharge voltage that can be set with high accuracy, and prevents deterioration in image quality.

The present invention also provides
The present invention relates to an electronic apparatus including any of the electro-optical devices described above.

The present invention also provides
The present invention relates to an electronic device including any of the source drivers described above.

  According to any one of the above-described inventions, it is possible to provide an electronic device to which a source driver that realizes precharging of a source line with a precharge voltage that can be set with high accuracy is applied.

1 is a diagram illustrating an outline of a configuration of an active matrix liquid crystal device according to an embodiment. The figure which shows the structure principal part of the LCD panel in the case of dividing and outputting 1 output of the source driver of this embodiment to the source line for 2 pixels. FIG. 6 is a diagram illustrating an outline of another configuration of an active matrix liquid crystal device according to the present embodiment. FIG. 4 is a block diagram illustrating a configuration example of the gate driver in FIG. 1 or FIG. 3. FIG. 4 is a block diagram of a configuration example of the source driver in FIG. 1 or FIG. 3. FIG. 6 is an operation explanatory diagram of the multiplexing circuit of FIG. 5. The figure which shows the chip image of the source driver of this embodiment. The figure which shows the source driver and LCD panel in the comparative example of this embodiment. The figure which shows an example of the voltage given to the display area side of the LCD panel of FIG. The figure which shows the detailed structural example of the output circuit of FIG. 5, and the demultiplexer of an LCD panel. The figure which shows the operation example of the source driver in this embodiment. FIG. 11 is an explanatory diagram of a control example of the output circuit of FIG. 10. The figure which shows the structure principal part of the source driver in the 1st modification of this embodiment. The block diagram of the structural example of the source driver in the 2nd modification of this embodiment. 1 is a block diagram of a configuration example of an electronic device according to an embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Liquid Crystal Device FIG. 1 shows an outline of the configuration of an active matrix liquid crystal device according to this embodiment. Here, an active matrix type liquid crystal device will be described, but the drive circuit in this embodiment can also be applied to other liquid crystal devices such as a passive matrix type liquid crystal device.

  The liquid crystal device 10 includes an LCD panel (display panel in a broad sense, electro-optical device in a broader sense) 20. The LCD panel 20 is a low-temperature polysilicon liquid crystal panel, for example, and is formed on a glass substrate, for example. On this glass substrate, a plurality of gate lines (scanning lines) GL1 to GLM (M is an integer of 2 or more) arranged in the Y direction and extending in the X direction, and a source line arranged in the X direction and extending in the Y direction, respectively. (Data line) are arranged. One pixel is composed of a plurality of color components, and a source line corresponding to the color component of each pixel is arranged on the LCD panel 20. In the following, it is assumed that one pixel is composed of 3 dots of RGB, and the LCD panel 20 includes source lines R1, G1, B1, R2, G2, B2,..., RN, GN, BN (N is 2 It is assumed that the above integer) is arranged.

  Source lines R1, G1, B1, R2, G2, B2,..., RN, GN, BN are connected to demultiplexers DMUX1 to DMUXj (1 <j <N, j is an integer) in units of a plurality One output signal of the driver 30 is divided and output by a plurality of demultiplexers. For example, when each demultiplexer is connected to k (k is an integer of 2 or more) source lines, N is j × k.

  Also, it corresponds to the intersection position of the gate line GLm (1 ≦ m ≦ M, m is an integer, and so on) and the source line Rn (or Gn or Bn) (1 ≦ n ≦ N, n is an integer, and so on). A pixel region (pixel) is provided, and a thin film transistor (hereinafter abbreviated as TFT) 22mn-R is disposed in the pixel region.

  The gate of the TFT 22mn-R is connected to the gate line GLn. The source of the TFT 22mn-R is connected to the source line Rn. The drain of the TFT 22mn-R is connected to the pixel electrode 26mn-R. A liquid crystal (electro-optical element in a broad sense) is sealed between the pixel electrode 26mn-R and a counter electrode 28mn-R facing the pixel electrode 26mn-R, thereby forming a liquid crystal capacitor (a liquid crystal element in a broad sense) 24mn-R. The transmittance of the pixel changes according to the applied voltage between the pixel electrode 26mn-R and the counter electrode 28mn-R. The counter electrode voltage Vcom is supplied to the counter electrode 28mn-R.

  Such an LCD panel 20 includes, for example, a first substrate on which pixel electrodes and TFTs are formed and a second substrate on which counter electrodes are formed, and a liquid crystal as an electro-optical material is interposed between the two substrates. It is formed by enclosing.

  Therefore, it can be said that the LCD panel 20 has a pixel electrode connected to the source line via the TFT as a switch element. In addition, the LCD panel 20 includes a plurality of gate lines, a plurality of source lines, a plurality of switch elements, and a plurality of pixel electrodes in which each pixel electrode is connected to each source line via each switch element. Can do.

  The liquid crystal device 10 includes a display driver (drive circuit in a broad sense) 90 that drives the LCD panel 20. The display driver 90 includes the source driver 30. The source driver 30 drives the source line of the LCD panel 20 based on the gradation data corresponding to each source output. More specifically, the source driver 30 divides and outputs the source outputs of the source outputs SO1 to SOj by the demultiplexers DMUX1 to DMUXj of the LCD panel 20 and outputs the source lines R1 to B1, R2 to B2,. ˜BN is supplied with a gradation voltage corresponding to the gradation data. In FIG. 1, the source output SOr (1 ≦ r ≦ j, r is an integer) of the source driver 30 is connected to the demultiplexer DMUXr, and the source line Rn is connected to the output of the demultiplexer DMUXr.

  In this embodiment, each of the demultiplexers DMUX1 to DMUXj of the LCD panel 20 divides and outputs one output of the source driver 30 to source lines for two pixels. However, the number of pixels is not limited to this. Absent.

  FIG. 2 shows an essential part of the LCD panel 20 when one output of the source driver 30 is divided and output to source lines for two pixels.

  FIG. 2 shows a configuration example of the demultiplexer DMUXr that divides the source output SOr of the source driver 30 into source lines R1n, G1n, B1n, R2n, G2n, and B2n for two pixels. Such a demultiplexer DMUXr includes demultiplex switches DSW1-r to DSW6-r.

  The demultiplex switch DSW1-r is switch-controlled by a multiplex control signal R1SEL. The demultiplex switch DSW2-r is switch-controlled by a multiplex control signal G1SEL. The demultiplex switch DSW3-r is switch-controlled by a multiplex control signal B1SEL. The demultiplex switch DSW4-r is switch-controlled by a multiplex control signal R2SEL. The demultiplex switch DSW5-r is switch-controlled by a multiplex control signal G2SEL. The demultiplex switch DSW6-r is switch-controlled by a multiplex control signal B2SEL.

  As shown in FIG. 1, the display driver 90 can include a gate driver (scan driver in a broad sense) 32. The gate driver 32 scans the gate lines GL1 to GLM of the LCD panel 20 within one vertical scanning period. The display driver 90 may have a configuration in which at least one of the source driver 30 and the gate driver 32 is omitted.

  The liquid crystal device 10 can include a power supply circuit 100. The power supply circuit 100 generates voltages necessary for driving the source lines and supplies them to the source driver 30. The power supply circuit 100 generates, for example, power supply voltages VDDH and VSSH necessary for driving a source line of the source driver 30 and a voltage of a logic unit of the source driver 30.

  The power supply circuit 100 generates a voltage necessary for scanning the gate line and supplies it to the gate driver 32.

  Further, the power supply circuit 100 generates a counter electrode voltage Vcom. In accordance with the timing of the polarity inversion signal POL generated by the source driver 30, the power supply circuit 100 generates a common electrode voltage Vcom that periodically repeats the high potential side voltage VCOMH and the low potential side voltage VCOML on the LCD panel 20. Output to electrode.

  The liquid crystal device 10 can include a display controller 38. The display controller 38 controls the source driver 30, the gate driver 32, and the power supply circuit 100 according to contents set by a host such as a central processing unit (hereinafter abbreviated as CPU) (not shown). For example, the display controller 38 sets an operation mode and supplies an internally generated vertical synchronization signal and horizontal synchronization signal to the source driver 30 and the gate driver 32.

  In FIG. 1, the liquid crystal device 10 includes the power supply circuit 100 or the display controller 38, but at least one of these may be provided outside the liquid crystal device 10. Alternatively, the liquid crystal device 10 may be configured to include a host.

  The source driver 30 may incorporate at least one of the gate driver 32 and the power supply circuit 100.

  Furthermore, some or all of the source driver 30, the gate driver 32, the display controller 38, and the power supply circuit 100 may be formed on the LCD panel 20. For example, in FIG. 3, the display driver 90 (the source driver 30 and the gate driver 32) is formed on the LCD panel 20. As described above, the LCD panel 20 includes a plurality of source lines, a plurality of gate lines, and a plurality of switch elements in which each switch element is connected to each gate line of the plurality of gate lines and each source line of the plurality of source lines. And a source driver for driving a plurality of source lines. A plurality of pixels are formed in the pixel formation region 80 of the LCD panel 20.

2. Gate Driver FIG. 4 shows a configuration example of the gate driver 32 of FIG. 1 or FIG.

  The gate driver 32 includes a shift register 40, a level shifter 42, and an output buffer 44.

  The shift register 40 includes a plurality of flip-flops in which each flip-flop is provided corresponding to each gate line and sequentially connected. When the shift register 40 holds the start pulse signal STV in the flip-flop in synchronization with the clock signal CPV, the shift register 40 sequentially shifts the start pulse signal STV to the adjacent flip-flop in synchronization with the clock signal CPV. The clock signal CPV input here is a horizontal synchronizing signal, and the start pulse signal STV is a vertical synchronizing signal.

  The level shifter 42 shifts the voltage level from the shift register 40 to a voltage level corresponding to the liquid crystal element of the LCD panel 20 and the transistor capability of the TFT. As this voltage level, for example, a high voltage level of 20 V to 50 V is required.

  The output buffer 44 buffers the scanning voltage shifted by the level shifter 42 and outputs it to the gate line to drive the gate line. The high potential side of the pulsed scanning voltage is a selection voltage, and the low potential side of the scanning voltage is a non-selection voltage.

  Note that the gate driver 32 scans a plurality of gate lines by selecting a gate line corresponding to the decoding result by the address decoder without scanning the gate line using a shift register as shown in FIG. Also good.

3. Source Driver FIG. 5 shows a block diagram of a configuration example of the source driver 30 of FIG. 1 or FIG.

  The source driver 30 includes an I / O buffer 50, a display memory 52, a line latch 54, a multiplexing circuit 56, a gradation voltage generating circuit 58, a DAC (Digital / Analog Converter) 60, a source line driving circuit 62, and a multi driving control circuit. 120 is included.

  For example, the gradation data D is input to the source driver 30 from the display controller 38. The gradation data D is input in synchronization with the dot clock signal DCLK and buffered in the I / O buffer 50. The dot clock signal DCLK is supplied from the display controller 38.

  The I / O buffer 50 is accessed by the display controller 38 or a host (not shown). The gradation data buffered in the I / O buffer 50 is written in the display memory 52. The gradation data read from the display memory 52 is output to the display controller 38 and the like after being buffered by the I / O buffer 50.

  The display memory (gradation data memory) 52 includes a plurality of memory cells provided corresponding to the output lines in which the memory cells are connected to the source lines. Each memory cell is specified by a row address and a column address. Each memory cell for one scan line is specified by a line address.

  The address control circuit 66 generates a row address, a column address, and a line address for specifying a memory cell in the display memory 52. The address control circuit 66 generates a row address and a column address when writing gradation data into the display memory 52. That is, the gradation data buffered in the I / O buffer 50 is written into the memory cell of the display memory 52 specified by the row address and the column address.

  The row address decoder 68 decodes the row address and selects a memory cell of the display memory 52 corresponding to the row address. The column address decoder 70 decodes the column address and selects a memory cell of the display memory 52 corresponding to the column address.

  When the gradation data is read from the display memory 52 and output to the line latch 54, the address control circuit 66 generates a line address. That is, the line address decoder 72 decodes the line address and selects a memory cell of the display memory 52 corresponding to the line address. Then, gradation data for one horizontal scan read from the memory cell specified by the line address is output to the line latch 54.

  The address control circuit 66 generates a row address and a column address when reading the gradation data from the display memory 52 and outputting it to the I / O buffer 50. That is, the gradation data held in the memory cell of the display memory 52 specified by the row address and the column address is read to the I / O buffer 50. The gradation data read to the I / O buffer 50 is extracted by the display controller 38 or a host (not shown).

  Therefore, in FIG. 5, the row address decoder 68, the column address decoder 70, and the address control circuit 66 function as a write control circuit that controls the writing of gradation data to the display memory 52. On the other hand, in FIG. 5, the line address decoder 72, the column address decoder 70, and the address control circuit 66 function as a readout control circuit that performs readout control of gradation data from the display memory 52.

  The line latch 54 latches the grayscale data for one horizontal scan read from the display memory 52 at the change timing of the latch pulse LP that defines one horizontal scan period. The line latch 54 includes a plurality of registers in which each register holds gradation data for one dot. The gradation data for one dot read from the display memory 52 is taken into each of the plurality of registers of the line latch 54.

The multiplexing circuit 56 includes multiplexers MPX _{1 to} MPX _j , and each multiplexer multiplexes the grayscale data for one horizontal scan latched by the line latch 54 in units of 2 pixels (= 6 dots) in a time division manner. Multiplexed data is generated.

  FIG. 6 shows an operation explanatory diagram of the multiplexing circuit 56 of FIG.

FIG. 6 shows an operation example of the multiplexer MPX _n among the multiplexers MPX _{1 to} MPX _j of the multiplexing circuit 56. Multiplexer MPX _n, the source line R1n, G1n, B1n, R2n, G2n, generates the multiplexed data time-division multiplexing the grayscale data corresponding to B2n. That is, the gradation data GD _{1 to} GD ₆ corresponding to the source lines R 1 n, G 1 n, B 1 n, R 2 n, G 2 n, B 2 n captured by the line latch 54 are multiplexed by the multiplexer MPX _n of the multiplexing circuit 56. Multiplex control signals R1SEL, G1SEL, B1SEL, R2SEL, G2SEL, and B2SEL that define time division timing are input to the multiplexers MPX _{1 to} MPX _j . Such multiplex control signals R1SEL, G1SEL, B1SEL, R2SEL, G2SEL, and B2SEL are generated in the multi-drive control circuit 120 of the source driver 30. The multi-drive control circuit 120 performs multiplex control so that any one of the multiplex control signals R1SEL, G1SEL, B1SEL, R2SEL, G2SEL, and B2SEL sequentially becomes H level within one horizontal scanning period. Signals R1SEL, G1SEL, B1SEL, R2SEL, G2SEL, and B2SEL are generated. Grayscale data corresponding to the multiplex control signal is output as multiplexed data during a period in which each multiplex control signal is at the H level.

  In FIG. 5, a gradation voltage generation circuit 58 generates a plurality of gradation voltages in which each gradation voltage (reference voltage) corresponds to each gradation data. More specifically, the grayscale voltage generation circuit 58 generates a plurality of grayscale voltages in which each grayscale voltage corresponds to each grayscale data based on the high potential side power supply voltage VDDH and the low potential side power supply voltage VSSH. .

The DAC 60 generates a gray scale voltage corresponding to the gray scale data multiplexed with the multiplexed data from each multiplexer of the multiplexing circuit 56 for each source output. More specifically, the DAC 60 outputs each grayscale data multiplexed into multiplexed data from each demultiplexer of the multiplexing circuit 56 out of a plurality of grayscale voltages generated by the grayscale voltage generation circuit 58. Then, a gradation voltage corresponding to each gradation data is selected, and the selected gradation voltage is output to output a multiplexed gradation voltage. Such a DAC 60 includes voltage selection circuits DEC _{1 to} DEC _j provided for each source output. Each voltage selection circuit outputs one gradation voltage corresponding to each gradation data of the multiplexed data from the plurality of gradation voltages from the gradation voltage generation circuit 58.

The source line drive circuit 62 includes output circuits OP _{1 to} OP _j . Each output circuit of the output circuits OP _{1 to} OP _j includes an operational amplifier connected as a voltage follower, performs impedance conversion using the multiplexed gradation voltage from each voltage selection circuit of the DAC 60, and drives its output. Each output circuit is supplied with, for example, a precharge voltage generated inside or outside the source driver 30, and each output circuit can precharge the source line prior to driving the source output.

  The multi-drive control circuit 120 supplies multiplex control signals R1SEL, G1SEL, B1SEL, R2SEL, G2SEL, and B2SEL to the demultiplexers DMUX1 to DMUXj of the LCD panel 20.

  FIG. 7 shows a chip image of the source driver 30 of this embodiment.

  Since the source driver 30 is disposed at the end portion of the LCD panel 20 along the arrangement direction of the source lines of the LCD panel 20, it is formed on an elongated chip. Therefore, in the source driver 30, each driver block is divided into a plurality of driver blocks provided to drive a plurality of source lines in consideration of layout efficiency, wiring length, and the like. In a region between the driver blocks, a logic unit shared by the driver blocks on both sides and a block for generating various power supply voltages are arranged.

  Therefore, in the source driver 30 in the present embodiment, the driver block including the output circuit for driving the source line of the LCD panel 20 is provided on both sides of the logic unit and the block LOB for generating various power supply voltages. The driver blocks DB1 and DB2 are divided, and the first and second driver blocks DB1 and DB2 are arranged side by side in the array direction DIR1 (first direction) of the source outputs SO1 to SOj. The first driver block DB1 has an output circuit for driving each source output block, and the first to pth (p is an integer of 2 or more) source output blocks arranged in the arrangement direction DIR1. SOB1 to SOBp are included. The second driver block DB2 has an output circuit for driving the source line by each source output block, and the (p + 1) th to qth (p + 1 <q, q is an integer) arrayed in the array direction DIR1. Source output blocks SOB (p + 1) to SOBq are included. The source output blocks of the first to qth source output blocks SOB1 to SOBq have the same configuration, and each of them has an output circuit, a voltage selection circuit, a multiplexer, and one source output block in FIG. A line latch and a display memory for one source output can be included.

  As described above, the number of source output blocks of the first driver block DB1 is p, and the number of source output blocks of the second driver block DB2 is (qp). Here, p may be different from (q−p), but in order to equalize the load from the block LOB to the first source output block SOB1 and the load from the block LOB to the qth source output block SOBq, p may be equal to (q−p).

  The output circuit of each source output block of the first to qth source output blocks SOB1 to SOBq can precharge the source line (precharge the output of the output circuit) prior to driving the source line. Therefore, the precharge voltage PV generated by the internal power supply circuit in the block LOB and the power supply circuit 100 outside the source driver 30 is supplied to each source output block. The source driver 30 has a precharge line PRL for supplying a precharge voltage to each source output block, and the precharge line PRL is in a region where an output circuit on the source output side of the source driver 30 is arranged. , Arranged along the arrangement direction DIR1. The precharge line PRL may be arranged in a straight line along the arrangement direction DIR1, or may be arranged substantially along the arrangement direction DIR1 while being bent in one or a plurality of locations in a direction perpendicular to the arrangement direction DIR1.

  A voltage supply point VPP of the precharge voltage PV from the internal power supply circuit in the block LOB or the power supply circuit 100 outside the source driver 30 is provided in the precharge line PRL arranged along the arrangement direction DIR1. The voltage supply point VPP is provided in a region between the first and second driver blocks DB1 and DB2. The voltage supply point VPP is provided so that the load up to the p-th source output block end EDp and the load up to the (p + 1) -th source output block end ED (p + 1) are equal to each other. A precharge voltage PV is supplied. For example, the wiring distance L1 between the voltage supply point VPP and the p-th source output block end EDp is equal to the distance L2 between the voltage supply point VPP and the (p + 1) th source output block end ED (p + 1). A voltage supply point VPP is provided.

  Here, it can be said that the p-th source output block end EDp is a position where the boundary on the block LOB side of the region of the first driver block DB1 intersects the precharge line PRL. The (p + 1) th source output block end ED (p + 1) can be said to be a position where the boundary on the block LOB side of the region of the second driver block DB2 intersects the precharge line PRL.

  Up to now, since the accuracy of the precharge voltage has not been required, the voltage supply point is determined even in the region between the first and second driver blocks DB1 and DB2 in consideration of the layout efficiency and the arrangement and wiring situation. The wiring between the first and second driver blocks DB1 and DB2 is provided in a vacant area so that the other wiring is prioritized or the wiring to the voltage supply point is shortest. However, in this embodiment, the voltage supply point is intentionally provided on the precharge line so that the load becomes equal while sacrificing the layout efficiency.

  By doing so, the precharge voltage of the output circuit of the p-th source output block SOBp and the precharge voltage of the output circuit of the (p + 1) -th source output block SOB (p + 1) can be made uniform. Therefore, the effective value of the pixel electrode connected to the source line driven by the output circuit of the pth source output block SOBp and the source line driven by the output circuit of the (p + 1) th source output block SOB (p + 1) are connected. The effective value of the pixel electrode to be applied can be made uniform, and the difference in effective value of the voltage applied to the pixel is caused by the difference in the precharge voltage, and the deterioration of the image quality due to this difference can be suppressed.

  Here, a comparative example of the present embodiment will be described.

  FIG. 8 shows a source driver and an LCD panel in a comparative example of the present embodiment.

  In the source driver in the comparative example, when the driver block including the output circuit for driving the source line of the LCD panel is divided into the first and second driver blocks DB1 and DB2, the first driver block DB1 is the LCD panel. The second driver block DB2 drives the source line of the right display area RAR of the display area DAR of the LCD panel.

  Here, the difference in the precharge voltage supplied via the precharge line PRL between the source output blocks of the first driver block DB1 and the source output block of the second driver block DB2 via the precharge line PRL. The difference between the supplied precharge voltages is small. This is because load differences (LD1 and LD2 in FIG. 8) due to differences in wiring lengths such as signal lines and bonding wires in the chip are also small between the source output blocks in each driver block.

  On the other hand, the source output block (pth source output block SOBp in FIG. 7) located at the end of the first driver block DB1 on the arrangement direction DIR1 side is opposite to the arrangement direction DIR1 of the second driver block DB2. When attention is paid to the source output block (the (p + 1) th source output block SOB (p + 1) in FIG. 8) located at the end on the direction side, the block LOB is arranged in the region between the two source output blocks. The load (LD3, LD4 in FIG. 8) resulting from the difference in length increases, and the influence of a minute difference in precharge voltage on the difference in effective value of the above voltages increases.

  FIG. 9 shows an example of voltages applied to the display area DAR side of the LCD panel of FIG.

  As shown in FIG. 9, the precharge voltage of the source line in the right display area RAR of the LCD panel does not reach the precharge voltage PV that should be given to the source line in the left display area LAR of the LCD panel. A precharge voltage PV is applied. In this case, the effective value of the voltage applied to the pixel connected to the source line of the right display region RAR is different from the effective value of the voltage applied to the pixel connected to the source line of the left display region LAR, and the precharge period Even if the same gradation voltage is applied in the drive period after the voltage setting period (in a broad sense), a difference occurs in the display image, which deteriorates the image quality.

  On the other hand, in the present embodiment, the driver blocks of the first and second driver blocks are provided so that the loads to the ends of the driver blocks are equal regardless of whether the number of source output blocks is the same or different. The precharge voltage PV is supplied to the voltage supply point VPP. Thereby, the precharge voltage of the source line driven by the pth source output block SOBp and the precharge voltage of the source line driven by the (p + 1) th source output block SOB (p + 1) can be made uniform. Therefore, the effective value of the voltage applied to the pixel connected to the source line of the right display region RAR is equal to the effective value of the voltage applied to the pixel connected to the source line of the left display region LAR, and the precharge period Even if the same gradation voltage is applied in the subsequent drive period, a situation in which a difference occurs in the display image can be reliably avoided. In particular, even when the number p of source output blocks of the first driver block DB1 is different from the number of source output blocks (qp) of the second driver block DB2, the display image is different from the comparative example. It will be possible to avoid the situation where the difference occurs.

  Although FIG. 7 illustrates the case where the source driver block is divided into two blocks, the number is not limited to the number of divisions of the source driver block. When a block such as a logic unit is arranged between two divided source driver blocks, voltage supply of a precharge line provided so that loads from the block to the ends of the source driver blocks on both sides are equal. The same applies to the case where the precharge voltage is supplied.

3.1 Detailed Configuration Example Next, a detailed configuration example of the source driver 30 in the present embodiment will be described.

  FIG. 10 shows a detailed configuration example of the output circuit of FIG. 5 and the demultiplexer of the LCD panel 20. However, in FIG. 10, the same parts as those in FIG.

FIG. 10 shows a configuration example of the output circuits OP ₁ and OP _{2 of} the source driver 30 connected to the source outputs SO 1 and SO ₂ and the demultiplexers DMUX 1 and DMUX ₂ of the LCD panel 20, but other output circuits and other demultiplexers are shown. The multiplexer has the same configuration. The following describes the output circuit OP ₁ and the demultiplexer DMUX 1.

Output circuit OP ₁ includes an operational amplifier AMP1, the first and second switching elements SW1-1, and SW2-1. The operational amplifier AMP1 drives the source line based on the gradation voltage corresponding to the gradation data. The first switch element SW1-1 is inserted between the precharge line PRL and the output of the operational amplifier AMP1. The second switch element SW2-1 is inserted between the precharge line PRL and the input of the operational amplifier AMP1.

  The demultiplexer DMUX1 performs an operation opposite to that of the multiplexer of the multiplexing circuit 56 of the source driver 30 corresponding to the demultiplexer. That is, each demultiplexer outputs the multiplexed gradation voltage from each output circuit of the source line driving circuit 62 to the six source lines in a time division manner. The time division output timing of the demultiplexer DMUX1 is synchronized with the time division timing of each multiplexer of the multiplexing circuit 56.

  FIG. 11 shows an operation example of the source driver 30 in the present embodiment.

  In FIG. 11, the source lines R1, G1, B1, R2, G2, and B2 connected to the gate lines GLm and GL (m + 1) will be described as an example, but the same applies to other source lines.

  For example, if a selection period in which the gate line GLm is selected is one horizontal scanning period (1H), a precharge period (voltage setting period in a broad sense) and a driving period are provided in one horizontal scanning period.

In the precharge period, as described above, the multiplex control signals R1SEL, G1SEL, B1SEL, R2SEL, G2SEL, and B2SEL from the source driver 30 are simultaneously set to the H level, and the demultiplexer DMUX1 is connected to the source lines R1, G1, B1, R2 , G2, B2 and the source output SO1 are electrically connected. The output circuit OP ₁ of the source driver 30, by outputting the precharge voltage PV to the source output SO1, the precharge period, at once the voltage of the source line R1, G1, B1, R2, G2, B2 The precharge voltage PV is set.

  Next, in the drive period after the precharge, the demultiplexer DMUX1 electrically connects the source output SO1 and the source lines R1, G1, B1, R2, G2, and B2 one by one. At this time, the source output SO1 is also supplied with the multiplexed gradation voltage. That is, during the drive period, the multiplex control signals R1SEL, G1SEL, B1SEL, R2SEL, G2SEL, and B2SEL are sequentially at the H level, and the voltage of the source output SO1 during the period in which each multiplex control signal is at the H level is The signal is supplied to the source line by the demultiplexer DMUX1.

  As is clear from FIG. 11, the effective value of the voltage applied to the pixel connected to the source line B2 among the source lines R1, G1, B1, R2, G2, and B2 is caused by the fluctuation of the precharge voltage PV. The influence to do is great. That is, the influence of the error of the precharge voltage PV is the largest for the pixel connected to the source line B2, and the smallest for the pixel connected to the source line R1. Therefore, by aligning the precharge voltages as in the present embodiment, even if there is a different influence for each dot due to multi-drive, it is possible to prevent deterioration of image quality uniformly, and the above precharge voltage PV can be prevented. The influence of errors can be minimized.

  In the present embodiment, not only the load of the precharge line PRL but also the output circuit is controlled as follows, so that the precharge voltage can be supplied to the source output with high accuracy.

Figure 12 is a diagram illustrative of a control example of the output circuit OP ₁ in FIG.

In Figure 12, but showing a control example of the output circuit OP _1, the other output circuit can be similarly controlled.

The precharge period of FIG. 11 can further include an amplifier high drive period, an amplifier low drive period, and an output precharge period. In the precharge period, the operational amplifier AMP1 has a given first current drive capability in a state where the first switch element SW1-1 is turned off and the second switch element SW2-1 is turned on in the amplifier high drive period. driving the output of the output circuit OP _1. In this way, it becomes a voltage of the source output SO ₁ to be set to the precharge voltage PV fast.

Thereafter, in the amplifier low drive period within the precharge period, the operational amplifier AMP1 is lower than the first current drive capability with the first switch element SW1-1 turned on and the second switch element SW2-1 turned on. the second current driving capability to drive the output of the output circuit OP _1. By doing so, it sets the precharge voltage PV output of the output circuit OP ₁ with high accuracy. The operational amplifier AMP1 includes drive transistors having different drive capacities in the output stage, and the output can be driven by any of the drive transistors.

  In the output precharge period, the first switch element SW1-1 is turned on and the second switch element SW1-2 is turned off. Since the voltage of the source output SO1 is slightly lower than the precharge voltage PV due to the ON resistance of the first switch element SW1-1, by supplying electric charges to the output of the operational amplifier AMP1 by the second current driving capability, the source output SO1 The voltage can be set to the precharge voltage PV with high accuracy. If the second current driving capability is lowered, an increase in current consumption can be suppressed.

In the drive period after the precharge period, turning off the first switching element SW1-1, while turning off the second switching element 2-1, the output of the operational amplifier AMP1 is based on the gray-scale voltage output circuit OP ₁ To drive.

  A control signal for switching the first and second switch elements SW1-1 and SW2-1 is generated in a control circuit (not shown) in the source driver 30.

  In the present embodiment, the source driver 30 that performs 6 multi-drive has been described, but the present invention is not limited to the number of multi-drives. The source driver 30 may be a non-multi drive source driver.

  In this embodiment, the case where the precharge voltage is supplied to the precharge line has been described. However, the present invention is not limited to the precharge voltage.

  For example, the precharge line may be replaced with a voltage supply line, and a voltage supply point may be provided on the voltage supply line as shown in FIG. Then, the voltage of the source line after short-circuiting the plurality of source lines of the LCD panel 20 is applied to the voltage supply point, and each output circuit of the source driver sets the voltage of the source line after short-circuiting to the plurality of source lines Thus, the source line may be driven based on the gradation data. Thus, prior to driving the source line, the charge once stored in the source line can be reused to drive the source line during the driving period, so that it is not necessary to replenish extra charges from the outside, and the above-mentioned book In addition to the effects of the embodiment, the power consumption can be reduced.

  Alternatively, the voltage supply line provided in place of the precharge line is provided with a voltage supply point as shown in FIG. 7, and a plurality of source lines and the counter electrode of the LCD panel 20 are short-circuited at the voltage supply point. The source line voltage is applied, and each output circuit of the source driver drives the source line based on the gradation data in a state where the voltage after short-circuiting the plurality of source lines and the counter electrode is set as the source line. May be. Here, the counter electrode is opposed to the pixel electrode connected to the source line via the TFT (switch element) via the electro-optical material. Even in this case, since the source line can be driven in the driving period by reusing the charge once stored in the source line and the charge stored in the counter electrode, it is not necessary to replenish the charge from the outside. In addition to the effects of the present embodiment, it is possible to achieve low power consumption. In particular, a significant effect of reducing power consumption can be obtained when performing polarity inversion driving.

4). Modified Example 4.1 First Modified Example In this embodiment, the source driver 30 has one precharge line, but may have a plurality of precharge lines.

  FIG. 13 shows a main part of the configuration of the source driver in the first modification of the present embodiment. However, in FIG. 13, the same parts as those in FIG. In the first modified example, the source driver 30 includes first and second precharge lines PRL1 and PRL2, and the first precharge voltage PRL1 is supplied with the first precharge voltage, A second precharge voltage is supplied to the precharge line PRL2. Each output circuit is supplied with the voltage of any precharge line.

  More specifically, the first precharge line PRL1 provided so that the load to the pth source output block end EDp and the load to the (p + 1) th source output block end ED (p + 1) are equal. The voltage of the highest potential that each output circuit outputs to the source line is supplied to the voltage supply point. This highest potential voltage is the highest potential voltage among the plurality of gradation voltages generated by the gradation voltage generation circuit 58. When the gradation voltage generation circuit 58 generates a plurality of gradation voltages by dividing resistance between the high potential side power supply voltage VDDH and the low potential side power supply voltage VSSH, the first precharge line PRL1 includes the first The voltage VDDH is supplied as the precharge voltage.

  The voltage supply point of the second precharge line PRL2 provided so that the load to the pth source output block end EDp and the load to the (p + 1) th source output block end ED (p + 1) are equal. In addition, the lowest potential voltage output from each output circuit to the source line is supplied. This lowest potential voltage is the lowest potential voltage among the plurality of gradation voltages generated by the gradation voltage generation circuit 58. When the gradation voltage generation circuit 58 generates a plurality of gradation voltages by dividing resistance between the high-potential-side power supply voltage VDDH and the low-potential-side power supply voltage VSSH, the second precharge line PRL1 includes the second The voltage VSSH is supplied as the precharge voltage.

Therefore, the output circuit OP _1, the third and fourth switch elements SW3-1, may include SW4-1. The third switch element SW3-1 supplies the voltage of the precharge line PRL1 to the operational amplifier AMP1 as a precharge voltage. The fourth switch element SW4-1 supplies the voltage of the precharge line PRL2 to the operational amplifier AMP1 as a precharge voltage. A switch control signal for ON / OFF control of the third and fourth switch elements SW3-1 and SW4-1 is also generated in a control circuit (not shown) of the source driver.

  In the first modified example, after each output circuit of the first and second driver blocks DB1 and DB2 supplies the first or second precharge voltage to the plurality of source lines of the LCD panel 20 at the same time, a plurality of output circuits are supplied. A plurality of source lines are driven in a time-sharing manner based on the multiplexed gradation data in which the gradation data of each dot for each pixel is multiplexed. For example, by making the precharge voltage different between the positive polarity and the negative polarity in polarity inversion driving, there is no need to perform unnecessary precharging, and both low power consumption and high speed driving period are achieved. Will be able to.

4.2 Second Modification Although the demultiplexer is provided on the LCD panel side in the present embodiment or the first modification, the present invention is not limited to this.

  FIG. 14 shows a block diagram of a configuration example of the source driver in the second modified example of the present embodiment.

  14, the same parts as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The source driver 300 in the second modification is different from the source driver 30 in FIG. 5 in that a separation circuit 64 is provided on the output side of the source line driving circuit 62. The separation circuit 64 includes demultiplexers DMUX1 to DMUXj, and each demultiplexer performs an operation opposite to that of the multiplexer of the multiplexing circuit 56 corresponding to the demultiplexer. That is, each demultiplexer separates and outputs the multiplexed gradation voltage from each output circuit of the source line driving circuit 62 into 6 (= k) source outputs. The demultiplexing operation timing of the demultiplexer is synchronized with the time division timing of each multiplexer of the multiplexing circuit 56. Thereby, the source driver 300 can drive T (T is an integer of 2 or more) source lines of the LCD panel.

  In this case, the LCD panel 20 can employ a configuration in which the demultiplexers DMUX1 to DMUXj in FIG. 1 or FIG. 3 are omitted. Possible amorphous silicon liquid crystal panels can be used.

5. Electronic Device FIG. 15 is a block diagram showing a configuration example of an electronic device according to this embodiment. Here, a block diagram of a configuration example of a mobile phone is shown as an electronic device. In FIG. 15, the same parts as those in FIG. 1 or FIG.

  The mobile phone 900 includes a camera module 910. The camera module 910 includes a CCD camera and supplies image data captured by the CCD camera to the display controller 38 in the YUV format.

  Mobile phone 900 includes LCD panel 20. The LCD panel 20 is driven by a source driver 30 (or source driver 300, the same applies hereinafter) and a gate driver 32. The LCD panel 20 includes a plurality of gate lines, a plurality of source lines, and a plurality of pixels.

  The display controller 38 is connected to the source driver 30 and the gate driver 32, and supplies gradation data in RGB format to the source driver 30.

  The power supply circuit 100 is connected to the source driver 30 and the gate driver 32 and supplies a driving power supply voltage to each driver. Further, the counter electrode voltage Vcom is supplied to the counter electrode of the LCD panel 20.

  The host 940 is connected to the display controller 38. The host 940 controls the display controller 38. The host 940 can supply the gradation data received via the antenna 960 to the display controller 38 after demodulating the modulation / demodulation unit 950. The display controller 38 displays on the LCD panel 20 by the source driver 30 and the gate driver 32 based on the gradation data.

  The host 940 can instruct transmission to another communication device via the antenna 960 after the modulation / demodulation unit 950 modulates the gradation data generated by the camera module 910.

  The host 940 performs gradation data transmission / reception processing, imaging of the camera module 910, and display processing of the LCD panel 20 based on operation information from the operation input unit 970.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, the present invention is not limited to being applied to driving the above-described liquid crystal display panel, but can be applied to driving electroluminescence and plasma display devices.

  In the invention according to the dependent claims of the present invention, a part of the constituent features of the dependent claims can be omitted. Moreover, the principal part of the invention according to one independent claim of the present invention can be made dependent on another independent claim.

10 liquid crystal device, 20 LCD panel, 22mn-R TFT,
26 mn-R pixel electrode, 24 mn-R liquid crystal capacitance, 28 mn-R counter electrode,
30 source drivers, 32 gate drivers, 38 display controllers,
40 shift registers, 42 level shifters, 44 output buffers,
50 I / O buffer, 52 display memory, 54 line latch,
56 multiplexing circuit, 58 gradation voltage generating circuit, 60 DAC,
62 source line drive circuit, 64 separation circuit, 66 address control circuit,
68 row address decoder, 70 column address decoder,
72 line address decoder, 90 display driver, 100 power supply circuit,
DB1 first driver block, DB2 second driver block,
DEC ₁ ~DEC _j voltage selection circuit, DMUX1~DMUXj demultiplexer,
GL1~GLM, GLm gate line, _MPX 1 ~MPX _j multiplexer,
OP ₁ ~OP _j output circuit, R1, G1, B1, R2 , G2, B2, ···, RN, GN, BN source line, SO1～SOj source output,
SOB1 to SOBq 1st to qth source output blocks, Vcom counter electrode voltage

Claims (13)

A source driver for driving a plurality of source lines of an electro-optical device,
Each source output block has an output circuit for driving a corresponding source line among the plurality of source lines, and is arranged in a first direction to a first source output block to pth (p is 2 or more) A first driver block including a source output block of
Each source output block has an output circuit for driving a corresponding source line among the plurality of source lines and is arranged in the first direction to (p + 1) th source output block to q (p + 1) A second driver block including <q, q are integers) source output blocks;
A first precharge voltage for supplying a first precharge voltage and a second precharge voltage for precharging the output of the output circuit of each source output block of the first driver block and the second driver block. Including a charge line and a second precharge line;
The second driver block is disposed on the first direction side of the first driver block,
The output circuits of the first driver block and the second driver block are:
After supplying one of the first precharge voltage and the second precharge voltage to the plurality of source lines simultaneously,
Driving each source line of the plurality of source lines in a time-sharing manner based on multiplexed gradation data in which gradation data of each dot for a plurality of pixels is multiplexed,
A load from the voltage supply point of the first precharge line to the pth source output block end, and a load from the voltage supply point of the first precharge line to the (p + 1) th source output block end Is supplied to the voltage supply point of the first precharge line provided to be equal to the highest potential voltage that the output circuit outputs to the source line as the first precharge voltage,
A load from the voltage supply point of the second precharge line to the pth source output block end, and a load from the voltage supply point of the second precharge line to the (p + 1) th source output block end Is supplied to the voltage supply point of the second precharge line provided so as to be equal to the lowest potential voltage output from the output circuit to the source line as the second precharge voltage. A featured source driver. In claim 1,
The output circuits of the first source output block and the second source output block are:
An operational amplifier for driving the corresponding source line based on the gradation voltage corresponding to the gradation data;
A first switch element inserted between the first or second precharge line and the output of the operational amplifier;
A second switch element inserted between the first or second precharge line and the input of the operational amplifier;
In the precharge period,
In a state where the first switch element is turned off and the second switch element is turned on, the operational amplifier drives the output of the output circuit with a first current driving capability, and then the first switch element is turned on. With the second switch element turned on, the operational amplifier drives the output of the output circuit with a second current drive capability lower than the first current drive capability, and then turns on the first switch element. , Turning off the second switch element,
In the drive period after the precharge period,
A source driver, wherein the operational amplifier drives an output of the output circuit based on a grayscale voltage in a state where the first switch element is turned off and the second switch element is turned off. In claim 1 or 2,
From the voltage supply point of the first precharge line to the connection point between the p-th output circuit block and the first precharge line, from the voltage supply point of the first precharge line, The load to the connection point between the (p + 1) th output circuit block and the first precharge line is equal,
From the voltage supply point of the second precharge line to the connection point between the p-th output circuit block and the second precharge line, from the voltage supply point of the second precharge line, A source driver, wherein loads to a connection point between the (p + 1) th output circuit block and the second precharge line are equal. In any one of Claims 1 thru | or 3,
A multiplexed voltage obtained by time-dividing a plurality of gradation voltages in one horizontal scanning period is input to the input of the operational amplifier,
The first source output block and the second source output block are:
A source driver comprising: a demultiplexer for separating the output of the operational amplifier into the plurality of source lines in synchronization with time division timing of the multiplexed voltage. In any one of Claims 1 thru | or 4,
Including a circuit block having an internal power supply circuit and a logic unit;
When the direction orthogonal to the first direction is the second direction,
Supply wiring for supplying a voltage to the voltage supply point is routed along the second direction between the p-th source output block and the circuit block,
The source driver, wherein the voltage supply point is located in the second direction of the circuit block. In any one of Claims 1 thru | or 5,
The source driver characterized in that the number p of source output blocks of the first driver block is equal to the number of source output blocks (qp) of the second driver block. In any one of Claims 1 thru | or 6.
The first precharge line is a positive precharge line in polarity inversion driving, and the second precharge line is a negative precharge line in polarity inversion driving. Source driver. In any one of Claims 1 thru | or 7,
The source driver, wherein the first precharge voltage and the second precharge voltage are voltages supplied from outside the source driver. Multiple gate lines,
Multiple source lines,
Each pixel is a plurality of pixels specified by each gate line of the plurality of gate lines and each source line of the plurality of source lines;
A gate driver that scans the plurality of gate lines;
9. An electro-optical device comprising: the source driver according to claim 1 that drives the plurality of source lines. Multiple gate lines,
Multiple source lines,
Each pixel is a plurality of pixels specified by each gate line of the plurality of gate lines and each source line of the plurality of source lines;
A gate driver that scans the plurality of gate lines;
The source driver according to claim 1, which drives the plurality of source lines;
An electro-optical device comprising: a demultiplexer that separates one of the outputs of the source driver into the plurality of source lines.   An electro-optical device comprising the source driver according to claim 1.   An electronic apparatus comprising the electro-optical device according to claim 9.   An electronic device comprising the source driver according to claim 1.

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