JP2012173499A - Method for driving liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for driving a liquid crystal display device in which a display mode for displaying information in a prescribed area defined in a whole display area with the remaining area displayed in a background color may be realized with small power consumption.SOLUTION: A gate driver successively selects, in each frame, a gate line to be set to a prescribed on potential or a prescribed off potential. When none of pixels disposed in a row corresponding to a selected gate line is disposed in a specific area for displaying an image, the gate line is set to the prescribed off potential. Alternatively, when any of pixels disposed in a row corresponding to a selected gate line is disposed in the specific area, the gate line is set to the prescribed on potential. A control part controls the gate driver in this manner on the basis of area definition information for defining the specific area.

Description

  The present invention relates to a drive device for a liquid crystal display device, and more particularly to a drive device for a liquid crystal display device that performs display in a predetermined area within a display area.

  In a liquid crystal display device having pixels arranged in a matrix, information may be displayed only in a predetermined area within the display area, and a background color may continue to be displayed in other areas. As an example of such a liquid crystal display device, for example, there is a liquid crystal display device for an instrument panel used in an instrument panel of a vehicle. In the instrument panel liquid crystal display device, there are several types of items to be displayed, such as “fuel remaining amount”, “shift status (shift lever setting status)”, “odometer value”, and the like. The location is predetermined. And the area | region which does not display those various items continues displaying a background color.

  As such a liquid crystal display device for an instrument panel, an active matrix type liquid crystal display device using a TFT (Thin Film Transistor) is often used. In general, in an active matrix liquid crystal display device using TFTs, when information is displayed in a predetermined region and the other region is a background color, the drive device displays the information in the predetermined region. The image data defining the image to be processed and the background color in the other area are input. The driving device selects each row line-sequentially and sets a potential corresponding to the image data of each pixel in the selected row for each source line of the liquid crystal display device. Therefore, the driving device sets a potential corresponding to the background color determined by the image data to the source line corresponding to the pixel that is the background portion in the selected row. If the pixel corresponding to the information display area is in the selected row, the driving device sets a potential corresponding to the pixel value determined by the image data in the source line corresponding to the pixel.

  The driving device sets the gate line of the selected row to a predetermined on potential (hereinafter simply referred to as an on potential), and sets the gate lines of other rows to a predetermined off potential (hereinafter simply referred to as an off potential). Set to). The on-potential is a potential for conducting between the source and drain of each TFT connected to the gate line. The off potential is a potential that brings the source and drain of each TFT connected to the gate line into a non-conductive state. In the TFTs arranged in individual rows, the gates of the TFTs are connected to the gate lines. The source line of the column in which the TFT is arranged is connected to the source of the TFT, and the pixel electrode arranged in the same pixel as the TFT is connected to the drain of the TFT. Therefore, when the gate line of the selected row is set to the on potential, the source and drain are brought into conduction in each TFT of the row, and as a result, the individual pixel electrodes of the row are respectively connected to the source line and the like. Become potential.

  Japanese Patent Application Laid-Open Publication No. 2004-228561 describes a display method for displaying an image in a specific area (display area) within the display area. Patent Document 1 describes that when a non-display area is set, a given non-display level voltage is driven to a signal line. In addition, all scan lines (gate lines) are line-sequentially driven at a predetermined odd frame period of 3 or more with reference to 0 frame, and in other frames, line-sequential drive is performed for scan lines corresponding to the display area. The scanning line corresponding to the non-display area is not driven.

JP 2006-3923 A

  When each row is sequentially selected and the potential corresponding to the image data is set for each source line including the source line corresponding to the background portion, the power consumption increases.

  In the display method described in Patent Document 1, all the scanning lines are line-sequentially driven at a predetermined odd frame period of 3 or more with reference to 0 frame. That is, assuming that the reference frame is 0 frame, all the scanning lines are line-sequentially driven in the (2 · k + 1) th frame. Therefore, it is not enough to reduce power consumption.

  Therefore, the present invention provides a drive device for a liquid crystal display device that can display information in an area defined in the entire display area and realize a display mode in which another area is a background color with low power consumption. The purpose is to do.

  A driving device for a liquid crystal display device according to the present invention includes a plurality of pixels arranged in a matrix, and includes a source line arranged along a column of pixels and a gate line arranged along a row of pixels. A liquid crystal display driving device for driving a liquid crystal display device, comprising: area defining information storage means for storing area defining information for defining a predetermined area for displaying an image within the display area of the liquid crystal display apparatus; A gate driver that sequentially selects a gate line to be set to determine whether to set a potential or a predetermined off-potential, and a connection end connected to the source line, and each time a gate line is selected, A source driver for controlling the state of the source line, and a control means for controlling the gate driver and the source driver. The control means selects the gate driver in each frame. If there is no pixel corresponding to the predetermined region among the pixels in the row corresponding to the gate line, the gate driver sets the potential of the gate line to be selected to a predetermined off potential, and the source driver When the connection end to be connected is set to a high impedance state, and there is a pixel corresponding to a predetermined region among the pixels in the row corresponding to the gate line selected by the gate driver, the gate driver selects the potential of the gate line to be selected. Is set to a predetermined on-potential, and the source driver sets the potential of the corresponding source line corresponding to the pixel corresponding to the predetermined area among the pixels in the row to a potential corresponding to the pixel value specified in the image data. The connection end to which each source line other than the corresponding source line is connected is set to a high impedance state.

  The gate driver sets the potentials of gate lines other than the selected gate line to a predetermined off potential.

  ADVANTAGE OF THE INVENTION According to this invention, the display mode which displays information in the area | region defined in the whole display area, and makes another area | region a background color is realizable with little power consumption.

Explanatory drawing which shows the example of the liquid crystal display device driven with the drive device of the liquid crystal display device by this invention. Explanatory drawing which shows the pixel electrode and TFT which are arrange | positioned at each pixel. Explanatory drawing which shows the example of a display of the image in a specific area | region. The block diagram which shows the example of the drive device of this invention. FIG. 3 is an explanatory diagram schematically showing a source driver 4. Explanatory view schematically showing a specific region 12 _a, 12 number of gate lines and source lines corresponding to _b of FIG. 1. The schematic diagram which shows the example of area | region prescription information. Explanatory drawing which shows the example of the waveform of a latch pulse. The timing chart which shows the condition of selection from the 1st line to the 3rd line. The timing chart which shows the condition of selection from the 31st line to the 33rd line.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of a liquid crystal display device driven by a driving device for a liquid crystal display device according to the present invention. The driving device 1 of the liquid crystal display device and the liquid crystal display device 10 according to the present invention are disposed on a substrate 30, for example. FIG. 1 illustrates a case where the driving device 1 is realized by a one-chip IC (Integrated Circuit). The drive device 1 is connected to an external system (not shown) via the wiring group 31 and receives image data and the like from the external system.

The liquid crystal display device 10 is, for example, a liquid crystal display device disposed on an instrument panel or the like of a vehicle. In the display area 11 formed by pixels (not shown) arranged in a matrix, an area for displaying information is determined in advance, and information is displayed in that area. Hereinafter, an area defined as an area for displaying information is referred to as a specific area. FIG. 1 illustrates a case where two specific areas 12 _a and 12 _b are defined. The specific area is determined by area defining information described later.

  FIG. 2 is an explanatory diagram showing pixel electrodes and TFTs arranged in each pixel of the liquid crystal display device 10. A set of the pixel electrode 21 and the TFT 22 is disposed in each pixel. Therefore, the set of the pixel electrode 21 and the TFT 22 is also arranged in a matrix. In FIG. 2, only one set of the pixel electrode 21 and the TFT 22 is shown.

  A common electrode 30 is provided so as to face the pixel electrodes 21 arranged in a matrix, and a liquid crystal (not shown) is sandwiched between each pixel electrode 21 and the common electrode 30. As shown in FIG. 2, each pixel electrode 21 paired with the TFT 22 is disposed at a position where the pixel electrode 21 faces the common electrode 30. The plurality of pixels form the display area 11 (see FIG. 1). Then, the light transmission state in each pixel is determined by the potential difference between the pixel electrode 21 and the common electrode 30 in each pixel (that is, the voltage applied to the liquid crystal in each pixel), and as a result, an image is displayed. In the present example, the case where the liquid crystal display device 10 is a normally black pixel in which no voltage is applied to the liquid crystal is black will be described as an example.

The liquid crystal display device 10 includes a plurality of source lines arranged along columns of pixels arranged in a matrix and a plurality of gate lines arranged along rows of the pixels. Here, a case where a source line is arranged for each column of pixel electrodes and a gate line is arranged for each row of pixel electrodes will be described as an example. That is, an example will be described in which each source line and each column have a one-to-one correspondence, and each gate line and each row has a one-to-one correspondence. In Figure 2, illustrates the k-th source line S _k from the left as viewed from the viewer side, and a gate line G _i of the i-th row.

TFT22 has a gate 22 _a as a terminal, and the drain 22 _b, and a source 22 _c. Gate 22 _a of each TFT21 is connected to the gate line corresponding to the row in which the TFT is disposed. The drain 22 _b of each TFT21 is connected to the pixel electrode 21 corresponding to the TFT. The source 22 _c of each TFT21 is connected to a source line corresponding to the column in which the TFT is disposed.

The common electrode 30, a predetermined potential for the common electrode _{(hereinafter,} referred to as _{V COM.)} Are set to. The potential is given on the potential of the gate line G _i (hereinafter, simply referred to as ON potential.) Is set to, when the gate 22 _a of the TFT is turned on potential, the source 22c, the drain 22b becomes conductive, pixel electrodes 21 are made to the source line _{S k} and equipotential. As a result, the potential difference between the pixel electrode 21 and the common electrode 30 is determined, and the display state in the pixel is determined. The potential is given off potential of the gate line G _i (hereinafter, simply referred to as off-potential.) When set to the source 22c, the drain 22b becomes nonconductive, the pixel electrode 21 and the common electrode in the immediately preceding The potential difference from 30 is maintained.

  Here, the on-potential is a potential for conducting between the source and drain of each TFT connected to the gate line. The off potential is a potential that brings the source and drain of each TFT connected to the gate line into a non-conductive state. The on potential is higher than the off potential.

  Here, the pixel electrode in the i-th row and the k-th column shown in FIG. 2 has been described as an example, but the potential setting mode for the pixel electrode has been described, but the potential setting mode for the other pixel electrodes is the same.

Since the liquid crystal display device 10 is normally black, the display area 11 is black when no voltage is applied to the liquid crystal (for example, when the power is off). In order to simplify the description, the outer edges of the specific areas 12 _a and 12 _b are illustrated in FIG. 1 and FIGS. 3 and 6 to be described later. However, when no voltage is applied, the outer edges of the specific areas 12 _a and 12 _b are Not visible. Further, when the liquid crystal display device 10 is driven, it is not necessary to drive so that the outer edges of the specific areas 12 _a and 12 _b are displayed.

FIG. 3 is an explanatory diagram showing a display example of images in the specific areas 12 _a and 12 _b . Elements identical to those shown in FIG. 1 are assigned the same reference numerals as in FIG. Drive device 1, as illustrated in FIG. 3, to display the desired information in the specific area ₁₂ a, 12 _b (information corresponding to the image data), the area other than the specific region ₁₂ a, 12 _b, a voltage The liquid crystal display device 10 is driven so that the color when not applied (ie, black) is obtained. Details of the driving operation will be described later.

FIG. 4 is a block diagram showing an example of the driving apparatus of the present invention. The drive device 1 of the present invention includes a control unit 2, a gate driver 3, and a source driver 4. The control unit 2 includes a register 7 inside. The drive device 1, the common electrode potential setting circuit (not shown) for setting the potential of the common electrode 30 in the V _COM also provided.

  4 shows the source driver 4 on the upper side of the liquid crystal display device 10 and the gate driver 3 on the lateral side of the liquid crystal display device 10 for the sake of simplicity. Thus, when the driving device 1 is realized by a one-chip IC, the source driver 4 and the gate driver 3 may be arranged side by side. Then, each source line S may be routed along a pixel column, and each gate line may be routed along a pixel row.

  The gate driver 3 selects the gate lines to be determined in line-sequentially as to whether to set the on potential or the off potential. That is, each gate line is selected one by one from the first row, and the potential of the selected gate line is set to either the on potential or the off potential. The control unit 2 determines whether the gate line selected by the gate driver 3 is set to the on potential or the off potential, and the gate driver 3 determines the potential of the selected gate driver according to the control unit 2 as the on potential or the off potential. Set to. Specifically, when there is a pixel corresponding to a specific region among the pixels in the row corresponding to the selected gate line, the gate driver 3 sets the potential of the selected gate line to the on potential. Further, when there is no pixel corresponding to the specific region among the pixels in the row corresponding to the selected gate line, the gate driver 3 sets the potential of the selected gate line to the off potential.

  Further, the gate driver 3 sets all gate lines other than the selected gate line to the off potential.

  FIG. 5 is an explanatory diagram schematically showing the source driver 4. The source driver 5 has a plurality of connection ends 5 connected to the source line S. One source line S is connected to one connection end 5. The number of connection ends 5 may be greater than the number of source lines S, and there may be remaining connection ends 5 without being connected to the source lines S. However, each source line S of the liquid crystal display device 10 is connected to the connection end 5 in the order in which the source lines are arranged. The source driver 5 determines the state of each source line connected to the connection end 5 every time a gate line is selected by the gate driver 3.

  The source driver 4 receives image data of each pixel in a row corresponding to the next selected gate line during a period in which one gate line is selected by the gate driver 3. The source driver 4 holds the image data for one row. The source driver 4 controls the state of each source line according to the control unit 2 when the gate line selects the next gate line.

  Specifically, when the pixel corresponding to the specific region does not exist in the pixels for one row, the source driver 4 sets each connection end 5 to which the source line S is connected to a high impedance state. As a result, each source line S enters a state where the potential is not set by the source driver 4 (floating).

  In addition, when the pixel corresponding to the specific region exists in the pixels for one row, the source driver 4 causes each source line corresponding to each pixel corresponding to the specific region (that is, each of the pixels corresponding to the specific region). The potential of each source line arranged in the pixel column is set to a potential corresponding to the image data of each pixel corresponding to the specific region in one row of image data. Further, the source driver 4 sets each connection end to which a source line other than each source line corresponding to each pixel corresponding to the specific region is connected to a high impedance state. Accordingly, each source line corresponding to each pixel corresponding to the specific region is set to a potential corresponding to the image data, and the other source lines are set to potentials that are not set by the source driver 4 (floating). State).

The image data represents pixel values of individual pixels included in the display area 11 as well as the specific areas 12 _a and 12 _b . That is, it also includes information on the pixel values of the pixels in the region (background region) other than the specific regions 12 _a and 12 _b .

  The register 7 included in the control unit 2 stores information that defines a specific area in which an image is displayed in the display area 11 of the liquid crystal display device 10 (hereinafter referred to as area defining information). Hereinafter, an example of the area defining information will be shown with reference to FIG. 6 and FIG.

FIG. 6 is an explanatory diagram schematically showing the number of gate lines and source lines corresponding to the specific regions 12 _a and 12 _b shown in FIG. 1. It is assumed that the display area 11 has 272 gate lines and 480 source lines.

The number of gate lines corresponding to a specific region 12 _a is 200 present (= 75 + 60 + 65). Specifically, the 31st to 230th lines from the top when viewed from the viewing side are the gate lines corresponding to the specific region _12a . Further, the number of source lines corresponding to a specific region 12 _a is 200 present, specifically, to 240 knots from 41 knots from the left as viewed from the viewing side is the source line corresponding to a specific region 12 _a.

The number of gate lines corresponding to a specific region 12 _b is 60 present. Specifically, the 106th to 165th lines from the top when viewed from the viewing side are the gate lines corresponding to the specific region _12b . Further, the number of source lines corresponding to a specific region 12 _b is 60 present, specifically, from 271 knots from the left as viewed from the viewing side to 330 knots is the source line corresponding to a specific region 12 _b.

FIG. 7 is a schematic diagram illustrating an example of area defining information stored in the register 7. FIG. 7 illustrates the area defining information indicating the specific areas 12 _a and 12 _b illustrated in FIG. 6. The region defining information shown in FIG. 7, a row of gate lines, together separated by start line and the previous line of each specific area 12 _a, 12 _b, each specific area 12 _a, 12 _b ending row and following its Separate with lines. For example, the initial line of the specific region 12 _a of line 31, separated by between 30 rows and 31 rows, since the end row of the specific region 12 _a of 230 row, separated by between 230 lines and 231 lines. The same applies to the specific area _12b . In addition, with the leftmost column as viewed from the viewing side, the source line row is _{divided by} the start column of each specific region 12 _a , 12 _b and the previous column, and each specific region 12 _a , 12 _b The end column of and the next column. For example, since starting row 41 column of the specific region 12 _a, separated by between 40 column and 41 column from the left, since the ending column of the specific region 12 _a left or 240 column, 240 column from the left And 241st column. The same applies to the specific area _12b .

  The area determined by the combination of each range obtained by dividing the position of the gate line as described above and each range obtained by dividing the position of the source line should be classified as a specific area or other area. Can do. For example, a gate line range of 1 to 30 rows and a source line range of 1 to 40 columns do not correspond to a specific region. Further, for example, a range of 31 to 105 rows of gate lines and a range of 41 to 240 columns of source lines corresponds to a specific region. In this way, for each combination of each range in which the position of the gate line is delimited and each range in which the position of the source line is delimited, it may be described whether it corresponds to a specific area or other area. In FIG. 7, “1” indicates that the area corresponds to the specific area, and “0” indicates that the area is outside the range of the specific area. Based on the region defining information thus determined, for example, it is understood that the region corresponding to the range of the 31st to 230th rows of the gate line and the range of the 41st to 240th columns of the source line is the specific region.

  However, FIG. 7 schematically illustrates an example of the expression form of the area defining information, and the expression form of the area defining information is not particularly limited. For example, it may be an expression that determines whether each pixel is a specific area or other area.

  Further, the area defining information stored in the register 7 can be changed. For example, the register 7 may be configured such that the stored contents can be changed by an SPI (Serial Peripheral Interface) or the like. By changing the area defining information, the specific area can be set to a desired position, or the position of the specific area can be changed.

  The control unit 2 controls the gate driver 3 and the source driver 4.

  The control unit 2 inputs a signal notifying the start of the frame at the start of the frame to the gate driver 3, and then inputs a signal instructing switching of the gate line to be selected (hereinafter referred to as a switching signal). To go. The control unit 2 also inputs a potential instruction signal that instructs the gate driver 3 to set the selected gate line to the on potential or the off potential. The gate driver 3 selects the gate line of the first row when the signal for notifying the start of the frame is input and then the switching signal is input first, and is instructed by the potential instruction signal for the gate line. A potential (on potential or off potential) is set. Thereafter, every time the switching signal is input, the gate lines in the second and subsequent rows are sequentially selected, and the potential (ON potential or OFF potential) indicated by the potential instruction signal is set for the selected gate line. Go.

  Here, the potential instruction signal is, for example, a control signal that is switched to a high level or a low level. In this example, when the potential instruction signal is at a high level, it means an instruction to set the selected gate line to the on potential, and when the potential instruction signal is at the low level, an instruction to set the selected gate line to the off potential. Means.

  The control unit 2 refers to the region defining information, and when there is no pixel corresponding to the specific region among the pixels in the row corresponding to the gate line selected by the gate driver 3, the control unit 2 sets the potential instruction signal to a low level. That is, the gate driver 3 is caused to set the potential of the selected gate line to the off potential. Further, the control unit 2 refers to the region defining information, and if there is a pixel corresponding to the specific region among the pixels in the row corresponding to the gate line selected by the gate driver 3, the control unit 2 sets the potential instruction signal to a high level. To. That is, the gate driver 3 is caused to set the potential of the selected gate line to the on potential.

  For example, when the gate driver 3 selects the gate line of the first row, the pixel corresponding to the specific region does not exist in the pixels of the first row (see FIG. 7). Therefore, at this time, the control unit 2 sets the potential instruction signal to a low level.

  For example, when the gate driver 3 selects the gate line of the 31st row, the pixel in the 31st row includes a pixel corresponding to the specific region. Specifically, it can be seen from the area defining information shown in FIG. 7 that the 41st to 240th pixels from the left correspond to the specific area. Therefore, at this time, the control unit 2 sets the potential instruction signal to the high level. The control unit 2 switches the level of the potential instruction signal according to the selected row based on the region defining information.

  Further, the control unit 2 inputs a signal for notifying the start of the frame at the start of the frame to the source driver 4 and then inputs a latch pulse. FIG. 8 is an explanatory diagram showing an example of the waveform of the latch pulse. During the period when one gate line is selected, the source driver 4 receives image data of each pixel in the row corresponding to the next selected gate line. Image data is stored. Then, after inputting the switching signal to the gate driver 3, the control unit 2 sets the latch pulse to the high level and further returns to the low level. When the source driver 4 detects the falling edge of the latch pulse, the source driver 4 determines the state of each source line according to the instruction of the control unit 2.

  When there is no pixel corresponding to the specific region among the pixels in the row corresponding to the gate line selected by the gate driver 3, the controller 2 connects each source line to the source driver 4. End 5 is set to a high impedance state. In addition, when there is a pixel corresponding to the specific region among the pixels in the row corresponding to the gate line selected by the gate driver 3, the control unit 2 instructs the source driver 4 among the pixels in the row. It is instructed to set the potential of the corresponding source line corresponding to the pixel corresponding to the specific region to a potential corresponding to the pixel value of the pixel specified by the image data. In addition, the control unit 2 causes the source driver 4 to set each connection end 5 to which each source line other than the corresponding source line is connected to a high impedance state.

  For example, when the gate driver 3 selects the gate line of the first row, the pixel corresponding to the specific region does not exist in the pixels of the first row (see FIG. 7). Therefore, at this time, the control unit 2 causes the source driver 4 to put each connection end 5 to which each source line is connected into a high impedance state.

  For example, when the gate driver 3 selects the gate line of the 31st row, the pixel in the 31st row includes a pixel corresponding to the specific region. Specifically, it can be seen from the area defining information shown in FIG. 7 that the 41st to 240th pixels from the left correspond to the specific area. Therefore, at this time, the control unit 2 sets the potentials of the source lines from the 41st column to the 240th column to the pixel values of the 41st to 240th pixels in the 31st row, respectively. The potential is set accordingly. In addition, the control unit 2 is connected to the source driver 4 with other source lines (the first to 40th source lines from the left and the 241st to 480th source lines from the left). Set the connection end to the high impedance state.

  Next, the operation of the present invention will be described with reference to a timing chart. It is assumed that the area defining information shown in FIG.

  When the power supply of the driving device is off, no voltage is applied to the liquid crystal of the liquid crystal display device, and the entire display area 11 is black. 9 and 10 are examples of timing charts in the first frame when the power is turned on from this state and driving is started. FIG. 9 shows the selection status from the first row to the third row. FIG. 10 shows the selection status from the 31st line to the 33rd line.

Incidentally, when the power is turned on, the common electrode potential setting circuit (not shown) sets the potential of the common electrode V _COM.

  The pixels corresponding to the specific area do not exist in the pixels from the first row to the 30th row (see FIG. 7). Therefore, the control unit 2 sets the potential instruction signal to the low level while instructing the gate driver 3 to select from the first row to the 30th row using the switching signal (see FIG. 9).

  When the switching signal is input for the first time after the start of the frame, the gate driver 3 selects the gate line of the first row. At this time, since the potential instruction signal input from the control unit 2 to the gate driver 3 is at a low level, the gate driver 3 sets the potential of the gate line in the first row to an off potential. Further, the gate driver 3 sets all the potentials of the unselected rows to the off potential. As a result, the potentials of the gate lines in all rows are turned off. Accordingly, in all the rows, in the TFT of each pixel, the source and the drain are in a non-conductive state, and the pixel electrode and the source line are also in a non-conductive state.

  In addition, since the pixels corresponding to the specific region do not exist in the pixels from the first row to the 30th row (see FIG. 7), the control unit 2 connects each source line to the source driver 4. Each connection end 5 is brought into a high impedance state.

  As a result, the potential of each source line and each pixel electrode is in a floating state. Since the potential difference between the pixel electrode and the common electrode was 0 V when the power supply was off, the potential difference was maintained, and at this time, all the pixels remain black. Therefore, in the first row where no pixel corresponding to the specific region exists, the potential difference between the pixel electrode and the common electrode is maintained at 0 V independently of the image data of the row.

When one of the selection period of the gate line and T _S, the control unit 2, T _S period the switching signal (so-called gate clock, not shown) to input to the gate driver 3, the row to be selected to the gate driver 3 Let them switch.

  The operation when the gate driver 3 sequentially selects the second row gate line, the third row gate line,... Under the control of the control unit 2 is the same.

  When the control unit 2 causes the gate driver 3 to select the gate line of the 31st row, the pixel corresponding to the specific region exists in the pixels of the 31st row (see FIG. 7). The signal is switched to high level (see FIG. 10). When the control unit 2 inputs a switching signal instructing selection of the 31st row to the gate driver 3, the gate driver 3 selects the 31st row gate line. At this time, since the potential instruction signal input from the control unit 2 to the gate driver 3 is at a high level, the gate driver 3 sets the potential of the gate line of the 31st row to the on potential. Further, the gate driver 3 sets all the potentials of the unselected rows to the off potential.

  Accordingly, in the TFT of the 31st row, the source and the drain are in a conductive state, and in the TFT of the other row, the source and the drain are maintained in a nonconductive state.

  In the 31st row, each pixel from the 41st to the 240th pixel from the left corresponds to a specific area (see FIG. 7). Therefore, the control unit 2 gives the source driver 4 the potentials of the source lines from the 41st column to the 240th column from the left and the pixel values of the 41st to 240th pixels from the left in the 31st row. In accordance with the instruction, the source driver 4 sets the potentials of the source lines from the 41st column to the 240th column from the left to potentials corresponding to the pixel values. Here, source line inversion driving is presented.

  At this time, the control unit 2 is connected to the source driver 4 with other source lines (source line from the leftmost to the 40th column and source lines from the 241st column to the 480th column). Each connecting end 5 is brought into a high impedance state.

  As a result, the potential of each source line from the 41st column to the 240th column from the left is set to a potential corresponding to the pixel value, and each of the 41st to 240th pixel electrodes from the left in the 31st row is also a pixel. The potential is set according to the value. Accordingly, in each of the pixels from the 41st pixel to the 240th pixel from the left in the 31st row, the potential difference between the pixel electrode and the common electrode becomes a potential corresponding to the pixel value indicated by the image data, and the display designated by the image data It becomes a state.

  In the other pixels in the 31st row, the pixel electrode and the source line are in a conductive state, but the connection end to which the source line is connected is in a high impedance state, so the potential of the pixel electrode is in a floating state. . Therefore, the potential difference between the pixel electrode and the common electrode is 0 V, which is the same as before. Therefore, those pixels (pixels other than the 41st to 240th pixels) remain black independently of the image data.

  The operation when the gate driver 3 sequentially selects the 32nd row gate line, the 33rd row gate line,... Under the control of the control unit 2 is the same.

  When the selected row is switched from the 31st row to the 32nd row, the gate line of the 31st row is turned off, and each pixel electrode and the source line of the 31st row are in a non-conductive state. As a result, the pixels in the 31st row maintain the display state determined when the 31st row is selected until the 31st row gate line is next selected. This also applies to the other rows.

  Further, when the gate driver 3 selects each of the 106th to 165th rows, the number of source lines to be set to the potential corresponding to the image data increases, but the operation when the 31st row is selected for other points. It is the same.

  The operation when the gate driver 3 sequentially selects the 166th to 230th rows is the same as the operation when the 31st row is selected.

  The operation when the last row (the 272nd row) is sequentially selected from the 231st row is the same as the operation when the first row is selected.

  As a result, for example, the display state in the display area 11 becomes the display state illustrated in FIG.

  The operation after the next frame is the same. However, in the previous frame, a potential is once set to the pixel electrode of the pixel corresponding to the specific region. Therefore, at the start of the frame, these pixel electrodes are at a potential corresponding to the image data of the previous frame.

  According to the present invention, when a gate line in a row where no pixel corresponding to a specific region is present is selected in each frame, the potential of the gate line is set to an off potential. In addition, in the selected row, the connection end of the source line in the column where the pixels other than the pixel corresponding to the specific region exist is set to the high impedance state. Therefore, an image can be displayed in a specific area while reducing power consumption.

  In particular, since an operation of “when selecting a gate line in a row in which no pixel corresponding to a specific region exists, the potential of the gate line is set to an off potential” is performed in each frame, it is described in Patent Document 1. The effect of reducing power consumption can be enhanced compared to the conventional method.

  Further, according to the present invention, since the first row to the last row are selected, it is not necessary to change the operation of the control unit 2 and the gate driver 3 even if the setting of the specific area is changed, and high versatility is realized. be able to.

  Further, by using a register that can change the stored information as the register 7, the area defining information can be changed. As a result, the specific area can be set to a desired position, or the position of the specific area can be changed. Can be.

  Next, a modification of the above embodiment will be described. In the above example, when there is a pixel corresponding to the specific region among the pixels of the selected row, the control unit 2 determines the pixel corresponding to the specific region among the pixels of the row to the source driver 4. It is instructed to set the potential of the corresponding source line to a potential corresponding to the pixel value of the pixel specified by the image data. Then, the control unit 2 causes the source driver 4 to set each connection end 5 to which each source line other than the source line is connected to a high impedance state.

At this time, the control unit 2 makes the source driver 4 from the first line and the specific area that enter the specific area with respect to the source lines other than the source line that sets the potential corresponding to the pixel value specified by the image data. You may instruct | indicate to set _VCOM only with respect to the 1st to exit. For example, in the above-described example, when the gate driver 3 selects the 31st row (see FIG. 10), the control unit 2 instructs the source driver 4 for each source line from the 41st column to the 240th column from the left. An instruction is given to set the potential to a potential corresponding to the pixel value of each pixel from the 41st pixel to the 240th pixel from the left in the 31st row. This is the same as in the above embodiment. At this time, the control unit 2 sets the potential of the other source lines (the source line from the leftmost to the 40th column and the source lines from the 241st column to the 480th column) to V _COM in the source driver 4. instructed to the source driver 4 according to the instruction, may be set source lines from the leftmost to 40 column, and the source line potential from 241 column to 480 column to V _COM . In this case, in the 31st row, in the pixels from the leftmost to the 40th pixel and from the 241st to 480th pixels, the pixel electrode becomes V _COM and the potential difference from the common electrode becomes 0V. Therefore, those pixels outside the specific region are displayed in black, and the same display as in the above embodiment can be realized. In the 32nd row, the source lines from the leftmost to the 40th column and the source lines from the 241st column to the 480th column are set in a high impedance state. Further, the potential of each source line for the first pixel out of the specific region, for example, the 41st to 240th pixels from the left in the 231st row of the gate line is set to _VCOM . Then, each source line in the 232nd row is set to a high impedance state. By doing so, the potential of each source line in the 232nd row can be further stabilized.

However, in this modification, power for setting the potential of the source line outside the specific region to V _COM is consumed. However, since the potential of the source line is set to V _COM only at the time of selecting the first row entering the specific region and the first row selecting from the specific region, the power consumption is reduced for all the rows in the specific region. is greatly improved as compared with the case where the potential of the source line to V _COM upon selection. Note that, from the viewpoint of enhancing the effect of suppressing power consumption, it is preferable to set the connection end to which the source line outside the specific region is connected to a high impedance state.

  Further, in the above embodiment, the case where the driving device 1 is realized by a one-chip IC is illustrated, but the control unit 2, the gate driver 3, and the source driver 4 may be realized as independent circuits. Further, the present invention can also be applied to an IPS (In Plane Switching) type liquid crystal display device.

  The present invention is suitably applied to a driving device for a liquid crystal display device that displays an image in a specific area within the display area. For example, the present invention can be suitably applied to a drive device that drives a liquid crystal display device for an instrument panel of a vehicle, an industrial liquid crystal display device, or the like.

DESCRIPTION OF SYMBOLS 1 Drive apparatus 2 Control part 3 Gate driver 4 Source driver 7 Register 10 Liquid crystal display device 11 Display area _12a , _12b Specific area | region

Claims (2)

A liquid crystal display device for driving a liquid crystal display device having a plurality of pixels arranged in a matrix and having a source line arranged along a column of pixels and a gate line arranged along a row of pixels. A driving device comprising:
Area defining information storage means for storing area defining information for defining a predetermined area for displaying an image in a display area of the liquid crystal display device;
A gate driver that sequentially selects a gate line to be set to determine whether to set a predetermined on potential or a predetermined off potential;
A source driver having a connection end connected to the source line and controlling the state of each source line each time a gate line is selected;
Control means for controlling the gate driver and the source driver,
Control means within each frame,
When there is no pixel corresponding to the predetermined region among the pixels in the row corresponding to the gate line selected by the gate driver, the gate driver is caused to set the potential of the gate line to be selected to a predetermined off potential, and the source driver is Set the connection end to which each source line is connected to a high impedance state,
When there is a pixel corresponding to a predetermined region among the pixels in the row corresponding to the gate line selected by the gate driver, the gate driver is caused to set the potential of the gate line to be selected to a predetermined ON potential, and the source driver is Among the pixels in the row, the potential of the corresponding source line corresponding to the pixel corresponding to the predetermined region is set to a potential corresponding to the pixel value specified in the image data, and each source line other than the corresponding source line A drive device for a liquid crystal display device, characterized in that the connection end to which the is connected is set to a high impedance state. The driving device of the liquid crystal display device according to claim 1, wherein the gate driver sets a potential of a gate line other than the gate line to be selected to a predetermined off potential.

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