The present disclosure relates to a display device including a plurality of pixels arranged in a matrix and performing a digital drive based on, for example, a differential digital signal, and a method of driving the same, and an electronic unit including such a display device.
In active matrix display devices, variations in a power supply potential and a ground potential in a pixel section are one factor affecting image quality. The variations are caused by a voltage drop, as a main factor, according to a data-line charge-discharge current during writing to a pixel. A current during writing is not constantly fixed, and is determined by a relationship between a data-line potential before writing and a signal potential to be written at a next timing; therefore, variation amounts of the power supply potential and the ground potential vary depending on write data (gray scale). In particular, in a pulse width modulation (PWM) mode liquid crystal display device performing writing of a digital value to a pixel, H (high)-level data as the power supply potential and L (low)-level data as the ground potential are applied to the pixel; however, as display is performed by applying a voltage between a pixel electrode and a counter electrode to a liquid crystal, variations in the power supply potential directly lead to image quality degradation. Such image quality degradation is more pronounced by an increase in the number of data lines for higher resolution, i.e., an increase in data-line charge-discharge current, and it is necessary to take measures against such image quality degradation.
It is desirable to provide a display device capable of suppressing potential variations in data lines to perform display with less image quality degradation caused by the potential variations, a method of driving the same, and an electronic unit.
According to an embodiment of the disclosure, there is provided a display device including: a plurality of data-line pairs arranged side by side along a first direction; a plurality of gate lines arranged side by side along a second direction; a display section including a plurality of pixels each disposed at an intersection of a data-line pair and a gate line and connected to one or both of the data-line pair; a data-line drive circuit supplying a positive-phase data signal to one of the data-line pair and a negative-phase data signal to the other of the data-line pair, and allowing the data-line pair to stay in a high-impedance state before writing of an image signal to the pixels; and a short circuit putting the data-line pair in a short-circuit state while the data-line pair stays in the high-impedance state, and then releasing the short-circuit state, in which, following the release of the short-circuit state, the positive-phase data signal, the negative-phase data signal or both thereof are written into the pixel as the image signal.
According to an embodiment of the disclosure, there is provided a method of driving a display device, the display device including a plurality of data-line pairs arranged side by side along a first direction, a plurality of gate lines arranged side by side along a second direction, a display section including a plurality of pixels each disposed at an intersection of a data-line pair and a gate line and connected to one or both of the data-line pair, a data-line drive circuit supplying a positive-phase data signal to one of the data-line pair and a negative-phase data signal to the other of the data-line pair, and allowing the data-line pair to stay in a high-impedance state before writing of an image signal to the pixels, and a short circuit putting the data-line pair in a short-circuit state while the data-line pair stays in the high-impedance state, and then releasing the short-circuit state, the method including, following the release of the short-circuit state, writing the positive-phase data signal, the negative-phase data signal or both thereof into the pixel as the image signal.
According to an embodiment of the disclosure, there is provided an electronic unit including a display device, the display device including: a plurality of data-line pairs arranged side by side along a first direction; a plurality of gate lines arranged side by side along a second direction; a display section including a plurality of pixels each disposed at an intersection of a data-line pair and a gate line and connected to one or both of the data-line pair; a data-line drive circuit supplying a positive-phase data signal to one of the data-line pair and a negative-phase data signal to the other of the data-line pair, and allowing the data-line pair to stay in a high-impedance state before writing of an image signal to the pixels; and a short circuit putting the data-line pair in a short-circuit state while the data-line pair stays in the high-impedance state, and then releasing the short-circuit state, in which, following the release of the short-circuit state, the positive-phase data signal, the negative-phase data signal or both thereof are written into the pixel as the mage signal.
In the display device, the method of driving the same, or the electronic unit according to the embodiment of the disclosure, the data-line pair is allowed to stay in the high-impedance state before writing of the image signal to the pixels. Moreover, the short circuit puts the data-line pair in the short-circuit state while the data-line pair stays in the high-impedance state, and then releases the short-circuit state. Then, the positive-phase data signal, the negative-phase data signal or both thereof are written into the pixel as the image signal.
In the display device, the method of driving the same, or the electronic unit according to the embodiment of the disclosure, the data-line pair is allowed to stay in the high-impedance state before writing of the image signal to the pixels, and the short circuit puts the data-line pair in the short-circuit state while the data-line pair stays in the high-impedance state, and then releases the short-circuit state. Then, the positive-phase data signal, the negative-phase data signal or both thereof are written into the pixel as the image signal. Therefore, potential variations in data lines are allowed to be suppressed, thereby performing display with less image quality degradation caused by the potential variations.
Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures.
Embodiments of the present application will be described below in detail with reference to the drawings.
[Configuration of Display Device]
The data-line group is configured of a plurality of data lines D1 to Dn and XD1 to XDn arranged side by side along a first direction (a horizontal direction). The plurality of data lines D1 to Dn and XD1 to XDn are in a differential configuration in which the data lines D1 to Dn are in positive phase and the data lines XD1 to XDn are in negative phase, and, for example, one data line Dn in positive phase and one data line XDn in negative phase configures a pair of data lines. Therefore, the data-line group is configured of a plurality of pairs of data lines arranged side by side along the horizontal direction. For example, one of the plurality of pairs of data lines is hereinafter referred to as a pair of data lines Dn/XDn. The gate-line group is electrically insulated from the data-line group. The gate-line group is configured of a plurality of gate lines G1 to Gm arranged side by side along a second direction (a vertical direction).
A data-line drive circuit 12 driving the data-line group and a gate-line drive circuit 13 driving the gate-line group are disposed around the display region 10. The data-line drive circuit 12 sequentially supplies, in the horizontal direction, image data signals (gray-scale signals) based on an image signal to the plurality of pixels 11 through the data-line group. More specifically, the data-line drive circuit 12 supplies a positive-phase data signal to one line (for example, Dn) of a pair of data lines (for example, Dn/XDn), and supplies a negative-phase data signal to the other line (for example, XDn) of the pair of data lines. The gate-line drive circuit 13 sequentially supplies, in the vertical direction, a gate signal (a scanning signal) to the plurality of pixels 11 through the gate-line group.
Each of the pixels 11 is disposed at an intersection of a pair of data lines (for example, Dn/XDn) and a gate line (for example, Gm). Each of the pixels 11 is connected to both of the pair of data lines (for example, Dn/XDn), and an image signal as a differential signal between the positive-phase data signal and the negative-phase data signal is written to the pixel 11. The display device is driven in, for example, a pulse width modulation (PWM) mode, and, for example, a digital value of 0 or 1 as the image signal is written to the pixel 11.
The display device includes a short circuit 14. The short circuit 14 is disposed between the display region 10 and the data-line drive circuit 12. The short circuit 14 is provided for each of the plurality of pairs of data lines, and allows the pair of data lines to be short-circuited. The short circuit 14 temporarily puts the pair of data lines in a short-circuit state before writing of the image signal to the pixel 11 to set a potential between the pair of data lines to an intermediate potential between a positive-phase potential and a negative-phase potential, and then, releases the short-circuit state, and then writing of the image signal to the pixel 11 is performed. The data-line drive circuit 12 allows the pair of data lines to stay in a high-impedance state before writing of the image signal to the pixel 11.
The plurality of pixels 11 have, for example, a configuration of a liquid crystal display panel. The liquid crystal display panel has a configuration in which a liquid crystal layer is sandwiched between a pixel substrate and a counter substrate, and the liquid crystal display panel allows light passing through the liquid crystal layer to be modulated by applying an electric field between the pixel substrate and the counter substrate.
(Specific Example of Drive Circuit for Each Pixel 11)
The drive circuit further includes a first transfer gate TG1, a second transfer gate TG2, a third transfer gate TG3, a fourth transfer gate TG4, a first inverter INV1, and a second inverter INV2.
The first transfer gate TG1 is connected to the gate line Gm and the data line Dn. The second transfer gate TG2 is connected to the gate line Gm and the data line XDn. The first inverter INV1 and the second inverter INV2 are disposed between the first transfer gate TG1 and the second transfer gate TG2. The third transfer gate TG3 and the fourth transfer gate TG4 are CMOS (Complementary Metal Oxide Semiconductor)-type circuits. A first terminal of the third transfer gate TG3 is connected between the first transfer gate TG1, and the first inverter INV1 and second inverter INV2. A first terminal of the fourth transfer gate TG4 is connected between the second transfer gate TG2, and the first inverter INV1 and the second inverter INV2. The pixel electrode 21 is connected to a second terminal of the third transfer gate TG3 and a second terminal of the fourth transfer gate TG4. A common potential (Vcom) is applied to the counter electrode 22.
[Operation of Display Device]
(Operation of Display Device According to Comparative Example)
First, as a comparative example, an operation and an issue of a display device not including the short circuit 14 (refer to
Parts (A) to (E) in
Variations in the power supply potential and the ground potential differ according to the state of data in such a manner, and images of the potentials of the pixel electrode 21 and the counter electrode 22 in a longer period are illustrated in parts (A) and (B) in
(Improved Operation Example)
An operation of the display device according to the embodiment obtained by improving the display device according to the above-described comparative example will be described below referring to
In the display device according to the embodiment, to reduce image quality degradation caused by variations in the power supply potential and the ground potential according to a charge-discharge current of the data-line group during writing of an image signal, the data-line group temporarily stays in a high-impedance state before writing of the image signal. Meanwhile, a positive-phase data line and a negative-phase data line forming a pair are short-circuited by the short circuit 14 to set the potential of the data-line group to an intermediate potential ((½) (H level+L level)) between the positive-phase potential and the negative-phase potential, and then writing is performed. Thus, the charge-discharge current of the data-line group when repeatedly performing writing of the image signal is made uniform to suppress variations in the power supply potential and the ground potential, thereby achieving an image quality improvement with less screen flickering. Screen flickering is caused by a decline in luminance or variations in luminance with time due to variations in a voltage applied to the liquid crystal.
Parts (A) to (E) in
Parts (A) and (B) in
[Effects]
As described above, in the display device according to the embodiment, potential variations in the data lines are suppressed to perform display with less image quality degradation caused by the potential variations.
In the configuration in
Next, a display device according to a second embodiment of the disclosure will be described below. It is to be noted that like components are denoted by like numerals as of the display device according to the first embodiment and will not be further described.
In the configuration illustrated in
A configuration example of such a circuit is illustrated in
In the display device illustrated in
In the configuration in
The technology of the present disclosure is not limited to the above-described embodiments, and may be variously modified. For example, the display devices according to the above-described respective embodiments are applicable to various electronic units having a display function. For example, the display devices according to the above-described respective embodiments are applicable to, for example, projection-type projectors, televisions, personal computers, and the like.
The present technology may have the following configurations.
(1) A display device including:
(2) The display device according to (1), in which
(3) The display device according to (1), in which
(4) The display device according to any one of (1) to (3), in which
(5) The display device according to any one of (1) to (3), in which
(6) A method of driving a display device, the display device including
(7) An electronic unit including a display device, the display device including:
It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
Number | Date | Country | Kind |
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2011-207986 | Sep 2011 | JP | national |
The present application is a continuation of U.S. patent application Ser. No. 13/612,045, filed Sep. 12, 2012, which application claims priority to Japanese Priority Patent Application No. JP2011-207986 filed in the Japan Patent Office on Sep. 22, 2011, the entire content of which is hereby incorporated by reference.
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Number | Date | Country | |
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20150235604 A1 | Aug 2015 | US |
Number | Date | Country | |
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Parent | 13612045 | Sep 2012 | US |
Child | 14695513 | US |