JP6063492B2 - Display device - Google Patents

Description

  The present disclosure relates to a display device that performs video display using a plurality of types of potential lines that hold gradation potentials.

  Conventionally, display devices using various types of display elements such as liquid crystal elements and organic EL (Electro Luminescence) elements have been developed. In such a display device, a peripheral circuit is generally arranged in a frame region (non-display region) located on the outer edge (outer periphery) of a display region (effective display region) having a plurality of pixels. The peripheral circuit includes a drive circuit that drives a plurality of pixels. For example, a scanning line drive circuit that sequentially drives the plurality of pixels, a signal line drive circuit that supplies video signals to the pixels to be driven, and the like. Can be mentioned.

  In recent years, a display device in which a predetermined pixel circuit (such as a memory circuit) is formed in each pixel has also been proposed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 08-286170

  By the way, with the recent increase in size and resolution of display devices, particularly in display devices incorporating the pixel circuit as described above, the yield in manufacturing is increased due to, for example, a short circuit between electrodes due to foreign matter or the like. There was a problem of being lowered.

  The present disclosure has been made in view of such problems, and an object of the present disclosure is to provide a display device and an electronic apparatus capable of improving yield in manufacturing.

  A display device according to the present disclosure includes a plurality of pixels each disposed in a display region, and a plurality of types of potential lines that are respectively disposed in the display region and hold different gradation potentials. Each of which includes a display element and a storage circuit for storing a video signal, and the gradation potential of one type of potential line selected based on the storage circuit among the plurality of types of potential lines is applied to the display element. A luminance gradient corresponding to the amount of variation in display luminance relative to the amount of variation in applied voltage or applied current to the display element. The resistance value of the first potential line holding the steep gradation potential is lower than the resistance value of the second potential line holding the gradation potential having a relatively gradual luminance gradient. .

  According to the display device of the present disclosure, the resistance value of the first potential line that holds the gradation potential with the relatively steep luminance gradient holds the gradation potential with the relatively gentle luminance gradient. Since the resistance value is lower than the resistance value of the second potential line, even if the potential of the first potential line fluctuates, the display to which the gradation potential of the first potential line is supplied is displayed. Variation in display luminance in the element can be suppressed. Therefore, for example, pixel line defects (defects of a plurality of pixels along the first potential line) can be avoided and point defects can be avoided, and the yield in manufacturing can be improved.

It is a block diagram showing the schematic structural example of the display apparatus which concerns on one embodiment of this indication. FIG. 2 is a circuit diagram schematically illustrating a configuration example of a pixel illustrated in FIG. 1. FIG. 3 is a circuit diagram illustrating an outline of an operation during white display in the pixel illustrated in FIG. 2. FIG. 3 is a circuit diagram illustrating an outline of an operation during black display in the pixel illustrated in FIG. 2. It is a circuit diagram for demonstrating the short circuit between the pixel electrodes in adjacent pixels. It is a circuit diagram for demonstrating the short circuit between the pixel electrode and counter electrode in a pixel. It is a characteristic view showing an example of the relationship between the applied voltage with respect to a liquid crystal element, and the transmittance | permeability of light. FIG. 3 is a schematic plan view illustrating a configuration example of a black potential line and a white potential line according to an embodiment. 10 is a schematic plan view illustrating a configuration example of a black potential line according to Modification 1. FIG. 12 is a circuit diagram schematically illustrating a configuration example of a pixel according to Modification 2. FIG. It is a figure showing the outline | summary of the gradation display operation | movement in the pixel shown in FIG. It is a figure showing the structural example of the black electric potential line which concerns on the modification 2, and a white electric potential line. It is a perspective view showing the external appearance of the example 1 of application of a display device of an embodiment and a modification. (A) is a perspective view showing the external appearance seen from the front side of the application example 2, (B) is a perspective view showing the external appearance seen from the back side. 12 is a perspective view illustrating an appearance of application example 3. FIG. 14 is a perspective view illustrating an appearance of application example 4. FIG. (A) is a front view of the application example 5 in an open state, (B) is a side view thereof, (C) is a front view in a closed state, (D) is a left side view, and (E) is a right side view, (F) is a top view and (G) is a bottom view.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (example in which resistance values of potential lines are varied due to differences in wiring width)
2. Modified example Modified example 1 (example in which the resistance values of the potential lines are made different from each other due to the difference in constituent materials (resistivity))
Modification 2 (example in which gradation display is performed using a video signal of a plurality of bits)
3. Application example (application example to electronic equipment)
4). Other variations

<Embodiment>
[Overall Configuration of Display Device 1]
FIG. 1 is a block diagram illustrating a schematic configuration of a display device (display device 1) according to an embodiment of the present disclosure. The display device 1 performs video display based on a video signal (not shown) supplied from the outside. Here, as an example, the display device 1 is a liquid crystal display device using a liquid crystal element (liquid crystal element LC) described later. ing. The display device 1 includes a liquid crystal display panel 3 and a backlight 4.

  The backlight 4 is a light source unit that emits light to the liquid crystal display panel 3. For example, the backlight 4 includes a light emitting element such as a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED). It is configured using.

  The liquid crystal display panel 3 includes a plurality of pixels 10, scanning line driving circuits 121 and 122, a signal line driving circuit 13, and connection terminals 14 on a substrate made of, for example, glass. The plurality of pixels 10 are arranged in the display area (effective display area) 11, and the scanning line driving circuits 121 and 122, the signal line driving circuit 13, and the connection terminal 14 are respectively on the periphery (outer edge) of the display area 11. It is arranged in the frame area (non-display area) located.

  The connection terminal 14 is a terminal for connecting various signal lines to the outside of the display device.

  The scanning line drive circuits 121 and 122 and the signal line drive circuit 123 (drive unit) are circuits that perform display drive of each pixel 10 based on a signal (video signal) input from the outside via the connection terminal 14. is there. Although these drive circuits will be described in detail later, the gradation potential (described later) of one selected potential line among a plurality of types of potential lines (here, a black potential line LB and a white potential line LW described later). The display drive is performed so that the black gradation potential or the white gradation potential to be supplied to the display element (here, a liquid crystal element LC described later) in each pixel 10.

  Each of the scanning line driving circuits 121 and 122 uses a plurality of scanning lines (gate lines) G extending along the horizontal line (row) direction to sequentially select the plurality of pixels 10 for each horizontal line, This is a circuit that selects pixels 10 to be driven in a line sequential manner (performs a line sequential scanning).

  The signal line driving circuit 13 is a circuit that supplies a video signal to the pixel 10 to be driven using a plurality of signal lines (data lines) S extending along the vertical line (column) direction. . In this signal line S, here, binary (binary data of “L (low)” signal (“0”) and “H (high)” signal (“1”)) is data 1 (digital data). Bit video signals are supplied.

  The plurality of pixels 10 are arranged in a matrix in the display area 11 described above.

[Detailed Configuration of Pixel 10]
FIG. 2 illustrates a circuit configuration example of each pixel 10. Each pixel 10 includes a liquid crystal element LC (display element) and a pixel circuit 2. The pixel circuit 2 includes a TFT (Thin Film Transistor) element Tr 1 and a memory circuit (memory circuit) 21. Further, each pixel 10 includes the above-described scanning line G and signal line S, common potential line (opposing potential line) VCOM, black potential line LB (first potential line), and white potential line LW (second potential line). Potential line).

  The black potential line LB and the white potential line LW are a plurality of types (two types here) of potential lines that hold different gradation potentials, and are formed so as to extend along the horizontal line direction. The black potential line LB is a potential line that holds a black gradation potential (for example, about 3 V to 4 V), and the white potential line LW is a potential line that holds a white gradation potential (for example, about 0 V to 1 V). is there. Here, in the present embodiment, the resistance value of the black potential line LB is set to be lower than the resistance value of the white potential line LW. Specifically, the wiring width of the black potential line LB is thicker than the wiring width of the white potential line LW. Details of the relationship between the black potential line LB and the white potential line LW will be described later.

  The liquid crystal element LC performs a display operation in accordance with pixel driving by the pixel circuit 2. The liquid crystal element LC is configured by using, for example, VA (Vertical Alignment) mode or TN (Twisted Nematic) mode liquid crystal. As an example, the liquid crystal element LC is a normally white mode liquid crystal element. One end (pixel electrode 20 side) of the liquid crystal element LC is connected to the drains of the TFT element Tr2 and the TFT element Tr3, and the other end (counter electrode side) is connected to the common potential line VCOM.

  Based on the video signal supplied via the signal line S, the pixel circuit 2 performs the gradation potential (black gradation potential or white gradation potential) of one of the black potential line LB and the white potential line LW. ) And supplies the liquid crystal element LC.

  The TFT element Tr1 is a switching element for supplying a video signal supplied from the signal line S to the memory circuit 21, and is an N-type transistor here. The gate of the TFT element Tr1 is connected to the scanning line G, and the source is connected to the signal line S.

  The memory circuit 21 is a circuit (latch circuit) that stores (temporarily holds) a video signal input from the signal line S via the TFT element Tr1, and here, an SRAM (slave having six TFT elements Tr2 to Tr7). Static Random Access Memory) circuit. Of these TFT elements Tr2 to Tr7, four TFT elements Tr2, Tr3, Tr4, Tr5 are N-type transistors, and two TFT elements Tr6, Tr7 are P-type transistors. The gate of the TFT element Tr2 is connected to the drain of the TFT element Tr1, the gate of the TFT element Tr4, the gate of the TFT element Tr6, the drain of the TFT element Tr5, and the drain of the TFT element Tr7. The source of the TFT element Tr2 is connected to the white potential line LW, and the drain is connected to the pixel electrode 20. The gate of the TFT element Tr3 is connected to the gate of the TFT element Tr5, the gate of the TFT element Tr7, the drain of the TFT element Tr4, and the drain of the TFT element Tr6. The source of the TFT element Tr3 is connected to the black potential line LB, and the drain is connected to the pixel electrode 20. The source of the TFT element Tr4 and the source of the TFT element Tr5 are each connected to the ground potential VSS, and the source of the TFT element Tr6 and the source of the TFT element Tr7 are each connected to the power supply potential VDD.

[Operation and Effect of Display Device 1]
(1. Display operation)
In the display device 1, the scanning line driving circuits 121 and 122 and the signal line driving circuit 13 perform display driving operations synchronized with each other based on an input signal supplied from the outside via the connection terminal 14. Specifically, each of the scanning line driving circuits 121 and 122 sequentially selects the pixels 10 for each horizontal line using the scanning line G, and performs line sequential scanning. Further, the signal line drive circuit 13 supplies a video signal via the signal line S to the pixel 10 to be driven. In the pixel 10 supplied with the video signal, the illumination light from the backlight 4 is modulated and emitted as display light. Thereby, video display based on the input signal is performed on the display device 1.

  Here, with reference to FIG. 3 and FIG. 4, the detail of the display operation in each pixel 10 is demonstrated. Here, as described above, an example in which the liquid crystal element LC is a normally white mode liquid crystal element will be described. In FIGS. 3 and 4, the TFT elements Tr <b> 1 to Tr <b> 7 are illustrated as switches for convenience of explanation. Therefore, in these drawings, the TFT element Tr1 is in the on state, assuming that the pixel 10 is to be driven.

  First, as shown in FIG. 3, when an “H” signal is supplied from the signal line S to the pixel 10 to be driven, the pixel 10 performs white display as follows. That is, since the “H” signal is supplied to the memory circuit 21 through the TFT element Tr1 and latched (temporarily held), the TFT elements Tr2, Tr4, Tr7 are turned on, and the TFT The elements Tr3, Tr5, Tr6 are turned off. Therefore, as indicated by an arrow P11 in FIG. 3, the potential of the white potential line LW (white gradation potential) is supplied to the pixel electrode 20 of the liquid crystal element LC, and white display is performed in the liquid crystal element LC.

  On the other hand, as shown in FIG. 4, when the “L” signal is supplied from the signal line S to the pixel 10 to be driven, the pixel 10 displays black as follows. That is, since the “L” signal is supplied to the memory circuit 21 via the TFT element Tr1 and latched, the TFT elements Tr3, Tr5, and Tr6 are turned on, contrary to the case of white display. The TFT elements Tr2, Tr4, Tr7 are each turned off. Therefore, as indicated by an arrow P12 in FIG. 4, the potential of the black potential line LB (black gradation potential) is supplied to the pixel electrode 20 of the liquid crystal element LC, and black display is performed in the liquid crystal element LC.

  Thus, in each pixel 10, based on the video signal supplied via the signal line S, the gradation potential (black gradation potential or black potential line LB) or one of the white potential lines LW is selected. White gradation potential) is selectively supplied to the liquid crystal element LC, and black display or white display (two-color display) is performed. In addition, when the plurality of pixels 10 in the display area 11 are configured by pixels of three primary colors, for example, red (R) pixels, green (G) pixels, and blue (B) pixels, using a color filter or the like. When two-color display is performed with pixels of each color, 2 × 2 × 2 = 8 colors are displayed as a whole.

(2. Action of characteristic parts)
Next, with reference to FIGS. 5 to 8, the operation of the characteristic part in the liquid crystal display panel 3 will be described in detail.

  First, in the liquid crystal display panel 3, there may be a case where a short circuit occurs between the electrodes due to foreign matters mixed due to process defects during manufacturing. That is, in the example shown in FIG. 5, a short circuit between the pixel electrodes 20 occurs between two adjacent pixels 10-1 and 10-2 along the vertical line direction due to foreign matters or the like (FIG. 5). (See arrow P21 in FIG. 5). In the example shown in FIG. 6, a short circuit occurs between the pixel electrode 20 side and the counter electrode side (common potential line VCOM side) in the liquid crystal element LC due to foreign matters or the like (arrow P22 in FIG. 6). reference). In FIG. 5, the liquid crystal element LC is not shown for the sake of simplicity.

  When such a short circuit occurs between the electrodes, as can be seen from arrows P21 and P22 in FIGS. 5 and 6, the potentials of the black potential line LB and the white potential line LW (black gradation potential and white gradation potential) are changed. Therefore, the display luminance will be changed as described below, and the manufacturing yield will be reduced.

  Here, FIG. 7 shows an example of the relationship (display characteristics) between the voltage applied to the liquid crystal element LC and the light transmittance (display luminance). In the example of FIG. 7, in the voltage range of applied voltage = 0 to 0.7V, the transmittance is substantially constant (about 0.40: corresponding to white gradation) and applied voltage = 2.5. Even in a voltage range of about ~ 4.0V, the transmittance is substantially constant (about 0: corresponding to black gradation). On the other hand, in the voltage range between them, the applied voltage = 0.7 to 2.5 V, the transmittance changes steeply between the white gradation and the black gradation. That is, in this voltage range (voltage range corresponding to the halftone), the luminance gradient (luminance slope) corresponding to the change in transmittance (variation amount) with respect to the change in applied voltage (variation amount) is steep.

  Therefore, when the black gradation potential and the white gradation potential change (change from the original applied voltage) due to the short circuit between the electrodes described above occurs, as shown by arrows P3B and P3W in FIG. The transmittance (display luminance) in the element LC varies. In particular, as can be seen from the arrows P3B and P3W here, the amount of variation in display luminance due to variation in black gradation potential is relatively larger than the amount of variation in display luminance due to variation in white gradation potential. . This is because the luminance gradient near the black gradation potential is relatively steeper than the luminance gradient near the white gradation potential. When the luminance variation caused by the short circuit between the electrodes in the pixel 10 occurs, the pixel 10 is not limited to a point defect, but is equivalent to one horizontal line along the black potential line LW or the white potential line LW. Thus, a line defect occurs in the plurality of pixels 10, and the manufacturing yield decreases. Such a problem may be particularly noticeable in a display device incorporating a pixel circuit as in this embodiment as the display device is increased in size and resolution.

  Therefore, in this embodiment, the resistance value of the potential line (here, the black potential line LB) that holds the gradation potential (here, the black gradation potential) having a relatively steep luminance gradient has the luminance gradient. It is lower than the resistance value of a potential line (here, white potential line LW) that holds a relatively gentle gradation potential (here, white gradation potential). That is, assuming that the resistance value of the black potential line LB is RB and the resistance value of the white potential line LW is RW, RB <RW. Note that the difference in resistance value at this time is desirably as large as possible, and the ratio of the resistance values is, for example, about RB: RW = 1.0: 1.5 to 1:10.

  Specifically, in the present embodiment, as shown in FIG. 8, the wiring width Wb of the black potential line LB is larger than the wiring width Ww of the white potential line LW (Wb> Ww). RB <RW. Note that the difference in the wiring width at this time is preferably as large as possible, and the wiring width ratio is, for example, about Wb: Ww = 1.5: 1.0 to 10: 1 (for example, Wb: Ww = 1). .5: 1.0).

  As a result, in this embodiment, as described above, a short circuit between electrodes caused by a foreign substance or the like occurs, and the potential of the black potential line LB (black gradation potential: gradation potential having a relatively steep luminance gradient). ) Fluctuates, the variation in display luminance in the liquid crystal element LC supplied with the black gradation potential can be suppressed.

  As described above, in the present embodiment, the resistance value RB of the black potential line LB that holds the black gradation potential having a relatively steep luminance gradient has the white gradation potential having a relatively gentle luminance gradient. Since the resistance value RW of the white potential line LW to be held is lower, even when the black gradation potential fluctuates, the display luminance in the liquid crystal element LC to which the black gradation potential is supplied varies. Can be suppressed. Therefore, for example, it is possible to avoid the line defect of the pixel 10 (here, the defect of the plurality of pixels 10 along the black potential line LB) and to perform the point defect, and it is possible to improve the manufacturing yield. In addition, the display image quality can be improved.

  Further, since the wiring width Wb of the black potential line LB is larger than the wiring width Ww of the white potential line LW (Wb> Ww), RB <RW is satisfied, so that the black potential line LB It is possible to cope with the problem by changing only the mask pattern when forming these potential lines without changing the constituent material of the white potential line LW or the like.

  Further, for example, the total value (Wb + Ww) of the wiring width Wb of the black potential line LB and the wiring width Ww of the white potential line LW is equivalent to the conventional one in which these wiring widths are equal (Wb = Ww). Then, it is possible to obtain the above effect without reducing the resolution of the pixel 10 in the display area 11 (while maintaining the resolution).

<Modification>
Subsequently, modified examples (modified examples 1 and 2) of the above embodiment will be described. In addition, the same code | symbol is attached | subjected to the same thing as the component in embodiment, and description is abbreviate | omitted suitably.

[Modification 1]
FIG. 9 schematically illustrates a planar configuration example of the black potential lines (black potential lines LB1 and LB2) according to the first modification. First, also in the display device 1 of this modification, as in the above embodiment, the resistance value RB of the black potential line LB holding the black gradation potential having a relatively steep luminance gradient has a relative luminance gradient. It is lower than the resistance value RW of the white potential line LW that holds the white gradation potential that is moderately low (RB <RW).

  However, in this modified example, unlike the embodiment, the resistivity of at least a part of the black potential line is lower than the resistivity of the white potential line LW, so that RB <RW. Yes. Specifically, in this modification, the black potential line is composed of two wirings (black potential lines LB1 and LB2) that are formed in different layers from each other and have different wiring constituent materials (wiring resistivity). Has been.

  Specifically, the black potential line LB1 (high resistivity wiring) is formed in the same layer as the white potential line LW (not shown in FIG. 9), and the same material (for example, for example, the white potential line LW) Molybdenum (Mo) or the like. Similar to the black potential line LB described in the embodiment, a plurality of black potential lines LB1 are provided so that each extends along the horizontal line direction.

  On the other hand, the black potential line LB2 (low resistivity wiring) is formed so as to be electrically connected to the black potential line LB1 via a contact or the like (not shown) in a layer different from the white potential line LW. It consists of a material (for example, aluminum (Al) etc.) whose resistivity is lower than that of the potential line LW. That is, if the resistivity in the black potential line LB1 and the white potential line LW is ρ1, and the resistivity in the black potential line LB2 is ρ2, ρ2 <ρ1. In addition, it is desirable that the difference in resistivity at this time is as large as possible. As a ratio of the resistivity, for example, about ρ1: ρ2 = 10: 1 to 100: 1 can be given.

  Unlike the black potential line LB1 and the white potential line LW, a plurality of black potential lines LB2 are provided so as to extend along the vertical line direction. In this modification, the plurality of black potential lines LB <b> 2 are thinned out with respect to the plurality of pixels 10 in the display area 11. That is, the black potential lines LB2 are arranged at a ratio of one black potential line LB2 to the plurality of pixels 10 along the horizontal line direction.

  As described above, in this modified example, the resistivity of at least some of the black potential lines is lower than the resistivity of the white potential line LW, so that RB <RW. Therefore, it is possible to obtain the same effect by the same operation as the above embodiment.

  Further, since the plurality of black potential lines LB2 are thinned out with respect to the plurality of pixels 10 in the display region 11, for example, a short circuit between the black potential lines LB2 made of a low resistivity material. It is possible to suppress the occurrence of defects and the like.

  In this modification, the case where the two black potential lines LB1 and LB2 having different wiring constituent materials (wiring resistivity) are formed in different layers has been described. The black potential lines LB1 and LB2 may be formed in the same layer. However, in general, it is difficult to form a plurality of wiring layers having different constituent materials in the same layer (or the manufacturing process becomes complicated), so it can be said that it is desirable to configure as in this modification.

[Modification 2]
(Circuit configuration of the pixel 20A)
FIG. 10 schematically illustrates a circuit configuration example of a pixel (pixel 10A) according to the second modification. The display device 1 of this modification is configured to perform multi-gradation display in each pixel 10A using a multi-bit (multiple-bit) video signal. Here, as an example, it is assumed that the video signal is composed of a 2-bit signal (each bit is binary data of “L” or “H”). That is, as described later, it is assumed that display of 2 bits × 2 gradations (black gradation and white gradation) = 4 gradations is performed in each pixel 10A. In FIG. 10, the liquid crystal element LC and the common potential line VCOM are not shown for the sake of simplicity.

  Therefore, each pixel 10A in the present modification includes a sub-pixel 10AL used for gradation display on the low bit side (first bit) and a sub-pixel used for gradation display on the high bit side (second bit). 10AH (multiple sub-pixel structures). The sub-pixel 10AL includes a TFT element Tr1L, a liquid crystal element LC including the pixel electrode 20L, and a memory circuit 21. Similarly, the sub pixel 10AH includes a TFT element Tr1H, a liquid crystal element LC including the pixel electrode 20H, and a memory circuit 21. Here, these sub-pixels 10AL and 10AH have a display area (corresponding to the area of the pixel electrode) having an area corresponding to the weighting of each bit in the video signal. That is, here, the area S (H) of the pixel electrode 20H in the sub-pixel 10AH on the high bit side is twice the area S (L) of the pixel electrode 20L in the sub-pixel 10AL on the low bit side. (S (H) = 2 × S (L)).

  Further, the scanning line G, the signal line S, the black potential line LB, and the white potential line LW are individually connected to each pixel 10A for each bit in the video signal. Specifically, the scanning line GL, the signal line SL, the black potential line LB (L), and the white potential line LW (L) are connected to the sub-pixel 10AL on the low bit side. Further, a scanning line GH, a signal line SH, a black potential line LB (H), and a white potential line LW (H) are connected to the sub-pixel 10AH on the high bit side. Note that the connection mode of each wiring in the sub-pixels 10AL and 10AH is the same as the connection mode in the pixel 10 in the embodiment, and thus description thereof is omitted.

(Display operation in pixel 10A)
With this configuration, in the pixel 10A, when the liquid crystal element LC is a normally white mode liquid crystal element as in the embodiment, a display operation is performed as shown in FIG. That is, first, when the “L” signal is supplied from the signal line SH and the “L” signal is supplied from the signal line SL to the pixel 10 to be driven, the sub-pixel 10AH (pixel electrode 20H) and the sub-pixel 10AL ( Both the pixel electrodes 20L) display black. Therefore, in this case, the black gradation display (display of the 0th gradation) having the lowest display luminance is obtained.

  Further, when the “L” signal is supplied from the signal line SH and the “H” signal is supplied from the signal line SL to the pixel 10 to be driven, the sub-pixel 10AH (pixel electrode 20H) displays black and the sub-pixel 10AL. In (pixel electrode 20L), white display is performed. Therefore, in consideration of the weighting between the areas S (H) and S (L) of the pixel electrodes 20H and 20L in the sub-pixels 10AH and 10AL, in this case, the gray level (gray) display with the second lowest display luminance ( 1st gradation display).

  When an “H” signal is supplied from the signal line SH and an “L” signal is supplied from the signal line SL to the pixel 10 to be driven, the sub-pixel 10AH (pixel electrode 20H) performs white display and the sub-pixel 10AL (pixel). The electrode 20L) displays black. Therefore, in consideration of the weighting of the areas S (H) and S (L) of the pixel electrodes 20H and 20L in the sub-pixels 10AH and 10AL, in this case, the display tone is the second highest gray level (gray) ( 2nd gradation display).

  When the “H” signal is supplied from the signal line SH and the “H” signal is supplied from the signal line SL to the pixel 10 to be driven, the sub pixel 10AH (pixel electrode 20H) and the sub pixel 10AL (pixel electrode) are supplied. 20L), white display is performed. Therefore, in this case, the white gradation display (the third gradation display) with the highest display luminance is obtained.

  Thus, in this modification, multi-gradation display is performed in each pixel 10A using a plurality of bits of video signals.

(Composition and action of characteristic parts)
Here, also in the present modification, as in the embodiment, the resistance value of the black potential line holding the black gradation potential having a relatively steep luminance gradient is a white floor having a relatively gradual luminance gradient. It is lower than the resistance value of the white potential line holding the potential adjustment. Specifically, in the sub-pixel 10AL on the low bit side, the resistance value RB (L) of the black potential line LB (L) is lower than the resistance value RW (L) of the white potential line LW (L). (RB (L) <RW (L)). Similarly, in the sub-pixel 10AH on the high bit side, the resistance value RB (H) of the black potential line LB (H) is lower than the resistance value RW (H) of the white potential line LW (H) ( RB (H) <RW (H)). Here, as an example, in the same manner as in the embodiment, if the resistance value is made different depending on the wiring width, the wiring width Wb (L) of the black potential line LB (L) in the sub-pixel 10AL on the low bit side is The white potential line LW (L) is thicker than the wiring width Ww (L) (Wb (L)> Ww (L)). Similarly, in the sub-pixel 10AH on the high bit side, the wiring width Wb (H) of the black potential line LB (H) is thicker than the wiring width Ww (H) of the white potential line LW (H) ( Wb (H)> Ww (H)).

  In this modification, the resistance value RB (H) of the black potential line LB (H) on the high bit side is equal to or lower than the resistance value RB (L) of the black potential line LB (L) on the low bit side. (RB (H) ≦ RB (L)). Similarly, the resistance value RW (H) of the white potential line LW (H) on the high bit side is equal to or lower than the resistance value RW (L) of the white potential line LW (L) on the low bit side (RW (H ) ≦ RW (L)). Here, as an example, as in the embodiment, if the resistance value is made different depending on the wiring width, the wiring width Wb (H) of the black potential line LB (H) on the high bit side is equal to the black voltage on the low bit side. The thickness is equal to or larger than the wiring width Wb (L) of the potential line LB (L) (Wb (H) ≧ Wb (L)). Similarly, the wiring width Ww (H) of the white potential line LW (H) on the high bit side is larger than the wiring width Ww (L) of the white potential line LW (L) on the low bit side (Ww). (H) ≧ Ww (L)).

  In summary, in the present modification, the resistance values RB (L) and RB (H) and the wiring widths Wb (L) and Wb (H) of the black potential lines LB (L) and LB (H) The resistance values RW (L) and RW (H) and the wiring widths Ww (L) and Ww (H) of the white potential lines LW (L) and LW (H) are shown in FIGS. A case where the conditional expression shown is satisfied is given.

That is, first, in the example shown in FIG. 12A, the following expression (1) (as an example, the following expression (2)) is satisfied.
RB (H) <RB (L) <RW (H) <RW (L) (1)
Wb (H)> Wb (L)> Ww (H)> Ww (L) (2)

In the example shown in FIG. 12B, the following expression (3) (for example, the following expression (4)) is satisfied.
RB (H) <RB (L) <RW (H) = RW (L) (3)
Wb (H)> Wb (L)> Ww (H) = Ww (L) (4)

Further, in the example shown in FIG. 12C, the following expression (5) (for example, the following expression (6)) is satisfied.
RB (H) = RB (L) <RW (H) = RW (L) (5)
Wb (H) = Wb (L)> Ww (H) = Ww (L) (6)

  As described above, in the present modification, RB (H) ≦ RB (L) and RW (H) ≦ RW (L) are satisfied, so in addition to the effects in the above embodiment, a video signal of a plurality of bits is converted. In particular, the following effects can be obtained when multi-gradation display is used. That is, first, considering the weighting of the area in the display region (pixel electrode), the luminance variation at the time of gradation display in the sub-pixel 10AH on the high bit side is more suitable for the gradation display on the sub-pixel 10AL on the low bit side. It is easy to see compared with the luminance fluctuation of (the influence of the display image quality deterioration is great). Therefore, as described above, by setting the resistance value of the high bit side potential line to be equal to or lower than the resistance value of the high bit side potential line (desirably, less than the resistance value of the high bit side potential line), Luminance fluctuation on the high bit side can be preferentially suppressed, and the display image quality can be further improved.

  In the present modification, the case where the resistance values of the potential lines are made different depending on the wiring width as in the embodiment has been described. However, the present invention is not limited to this, and as in the first modification, the resistivity ( The resistance values of the potential lines may be varied depending on the difference in the constituent materials of the wiring.

  In this modification, the case where the video signal is made up of a 2-bit signal has been described. However, the present invention is not limited to this, and the video signal may be made up of a signal of 3 bits or more.

<Application example>
Subsequently, application examples of the display device 1 described in the above embodiment and the modified examples will be described with reference to FIGS. The display device 1 according to the above-described embodiment can be applied to electronic devices in various fields such as a television device, a digital camera, a notebook personal computer, a mobile terminal device such as a mobile phone, or a video camera. In other words, the display device 1 can be applied to electronic devices in various fields that display a video signal input from the outside or a video signal generated inside as an image or video.

(Application example 1)
FIG. 13 illustrates an appearance of a television device to which the display device 1 is applied. The television device has a video display screen unit 300 including a front panel 310 and a filter glass 320, for example, and the video display screen unit 300 is configured by the display device 1.

(Application example 2)
FIG. 14 shows the appearance of a digital camera to which the display device 1 is applied. The digital camera includes, for example, a flash light emitting unit 410, a display unit 420, a menu switch 430, and a shutter button 440, and the display unit 420 includes the display device 1.

(Application example 3)
FIG. 15 shows the appearance of a notebook personal computer to which the display device 1 is applied. The notebook personal computer includes, for example, a main body 510, a keyboard 520 for inputting characters and the like, and a display unit 530 that displays an image. The display unit 530 is configured by the display device 1.

(Application example 4)
FIG. 16 shows the appearance of a video camera to which the display device 1 is applied. This video camera includes, for example, a main body 610, a subject photographing lens 620 provided on the front side surface of the main body 610, a start / stop switch 630 at the time of photographing, and a display 640. The display unit 640 includes the display device 1.

(Application example 5)
FIG. 17 shows the appearance of a mobile phone to which the display device 1 is applied. For example, the mobile phone is obtained by connecting an upper housing 710 and a lower housing 720 with a connecting portion (hinge portion) 730, and includes a display 740, a sub-display 750, a picture light 760, and a camera 770. Yes. Of these, the display 740 or the sub-display 750 is constituted by the display device 1.

<Other variations>
Although the present technology has been described with the embodiment, the modification, and the application example, the present technology is not limited to the embodiment and the like, and various modifications can be made.

  For example, in the above-described embodiment, the case where the liquid crystal element LC is formed of a normally white mode liquid crystal element has been described. However, the present invention is not limited thereto, and the liquid crystal element LC is formed of a normally black mode liquid crystal element. Also good. In this case, the relationship between the black potential line LB and the white potential line LW in the luminance gradient described above is reversed (the white gradient potential is relatively steeper than the black gradation potential). Therefore, in this case, contrary to the above-described embodiment, the resistance value RW of the white potential line LW (first potential line) is equal to the resistance value RB of the black potential line LB (second potential line). What is necessary is just to make it low compared (RW <RB).

  In the above-described embodiment and the like, a case where a plurality of types of potential lines are composed of two types of potential lines, a black potential line LB that holds a black gradation potential and a white potential line LW that holds a white gradation potential. Although described, the present invention is not limited to this case, and video display may be performed using three or more types of potential lines.

  Further, in the above-described embodiment, the case where the storage circuit in each pixel is an SRAM circuit has been described. However, the present invention is not limited to this. For example, another storage circuit such as a DRAM (Dynamic Random Access Memory) is used. Also good. That is, the present technology can be applied to any display device in which the gradation of the display element is determined according to the potential selectively supplied from a plurality of types of potential lines.

  In addition, the configurations described in the above embodiments and the like (embodiments, modified examples 1 and 2) may be arbitrarily combined.

  In the above-described embodiment and the like, the case where the display element in each pixel is the liquid crystal element LC (in the case of a liquid crystal display device) has been described. That is, the display element may be composed of another display element such as an organic EL element (may be a display device of another display method). In the case of this organic EL element, the aforementioned luminance gradient is defined by the relationship between the applied voltage or / and the applied current and the display luminance. That is, in other display elements as well, as described in the above embodiments and the like, fluctuations in display luminance with respect to gradation potentials supplied from the respective potential lines and fluctuation amounts of applied voltage or applied current to the display elements. The present technology can be applied by adjusting the resistance value of each potential line according to the relationship of the luminance gradient corresponding to the quantity. Note that the luminance of the display element in that case is, for example, the light emission intensity of each pixel in a self-luminous display device, and the brightness of each pixel in an electrophoretic electronic paper, for example. It can be defined according to characteristics.

In addition, this technique can also take the following structures.
(1)
A plurality of pixels including a display element;
A plurality of types of potential lines holding different gradation potentials;
A driving unit that performs display driving of each pixel based on a video signal so that a gradation potential of one type of potential line selected from the plurality of types of potential lines is supplied to the display element; Prepared,
The resistance value of the first potential line holding the gradation potential having a relatively steep luminance gradient corresponding to the variation amount of the display luminance with respect to the variation amount of the applied voltage or applied current to the display element is the luminance gradient. The display device is lower than the resistance value of the second potential line which holds a relatively gentle gradation potential.
(2)
The display device according to (1), wherein a wiring width of the first potential line is larger than a wiring width of the second potential line.
(3)
The display device according to (1) or (2), wherein a resistivity of at least a part of the wiring in the first potential line is lower than a resistivity of the second potential line.
(4)
The first potential line is
A high resistivity wiring formed in the same layer as the second potential line and made of the same material as the second potential line;
A low resistivity wiring made of a material having a lower resistivity than that of the second potential line, which is formed so as to be electrically connected to the high resistivity layer in a layer different from the second potential line. The display device according to (3).
(5)
The display device according to (4), wherein a plurality of the low resistivity wirings are provided, and the plurality of low resistivity wirings are thinned out with respect to the plurality of pixels.
(6)
The video signal comprises a multi-bit signal,
Each pixel includes a plurality of sub-pixels having a display area having an area corresponding to the weighting of each bit in the video signal,
The first and second potential lines are individually provided for each bit in the video signal, and the resistance values of the first and second potential lines corresponding to the high bit side correspond to the low bit side. The display device according to (1), wherein the display device is equal to or less than a resistance value of the first and second potential lines.
(7)
The wiring width of the first and second potential lines corresponding to the high bit side is larger than the wiring width of the first and second potential lines corresponding to the low bit side. The display device described.
(8)
The plurality of types of potential lines are composed of a black potential line holding a black gradation potential and a white potential line holding a white gradation potential,
The driving unit performs the display driving so that one selected from the black gradation potential and the white gradation potential is supplied to the display element. The display device according to any one of (7).
(9)
The display device according to (8), wherein the first potential line is the black potential line, and the second potential line is the white potential line.
(10)
Each pixel is
The display element;
The display device according to any one of (1) to (9), further comprising: a pixel circuit that selects a gradation potential of the one type of potential line based on the video signal and supplies the selected potential potential to the display element.
(11)
The display device according to (10), wherein the pixel circuit includes a storage circuit that stores the video signal.
(12)
The display device according to any one of (1) to (11), wherein the display element is a liquid crystal display element.
(13)
A display device,
The display device
A plurality of pixels including a display element;
A plurality of types of potential lines holding different gradation potentials;
A driving unit that performs display driving of each pixel based on a video signal so that a gradation potential of one type of potential line selected from the plurality of types of potential lines is supplied to the display element; Have
The resistance value of the first potential line holding the gradation potential having a relatively steep luminance gradient corresponding to the variation amount of the display luminance with respect to the variation amount of the applied voltage or applied current to the display element is the luminance gradient. Is lower than the resistance value of the second potential line that holds the gradation potential that is relatively gentle.

DESCRIPTION OF SYMBOLS 1 ... Display apparatus 10, 10-1, 10-2, 10A ... Pixel, 10AL, 10AH ... Sub pixel, 11 ... Display area, 121, 122 ... Scan line drive circuit, 13 ... Signal line drive circuit, 14 ... Connection Terminal, 2 ... pixel circuit, 20, 20L, 20H ... pixel electrode, 21 ... memory circuit (memory circuit), 3 ... liquid crystal display panel, 4 ... backlight, G, G1, G2, GL, GH ... scanning line, S, SL, SH: signal line, VCOM: common potential line (opposing potential line), LB, LB1, LB2, LB (L), LB (H) ... black potential line, LW, LW (L), LW (H ) ... White potential line, LC ... Liquid crystal element, Tr1 to Tr7, Tr1L, Tr1H ... TFT element, VDD ... Power supply potential, VSS ... Ground potential, Wb, Ww, Wb (L), Wb (H), Ww (L) , Ww (H): wiring width, ρ1, ρ2: resistivity, S (L), S (H)... Area, RB (L), RB (H), RW (L), RW (H).

Claims (7)

A plurality of pixels respectively arranged in the display area;
A plurality of types of display area potential lines that are arranged in the display area and hold different gradation potentials;
With
Each of the plurality of pixels is
A display element;
Including a storage circuit for storing a video signal, and a gradation potential of one type of display area potential line selected based on the storage circuit among the plurality of types of display area potential lines is applied to the display element; A pixel circuit for driving the display of each pixel,
Including
A resistance value of a potential line in the first display area that holds a gradation potential having a relatively steep luminance gradient corresponding to a variation amount of display luminance with respect to a variation amount of applied voltage or applied current to the display element, The display device, wherein the brightness gradient is lower than a resistance value of a potential line in the second display region that holds a gradation potential that is relatively gentle. The wiring width of the first display area potential line, the display device according to claim 1 which is thicker than the wiring width of the second display region potential line. The display device according to claim 1, wherein a resistivity of at least a part of the wiring in the first display area potential line is lower than a resistivity of the second display area potential line. The potential line in the first display area is
Wherein formed on the second display potential line in the same layer region, and the high resistivity wiring made of the same material as the second display region potential line,
A low-resistance material formed so as to be electrically connected to the high resistivity wiring in a layer different from the second display region potential line and having a lower resistivity than the second display region potential line. The display device according to claim 3, comprising: a resistivity wiring. The display device according to claim 4, wherein a plurality of the low resistivity wirings are provided, and the plurality of low resistivity wirings are thinned out with respect to the plurality of pixels. The plurality of types of display area potential lines are composed of a black potential line holding a black gradation potential and a white potential line holding a white gradation potential,
A drive unit that performs the display drive so that one selected from the black gradation potential and the white gradation potential is supplied to the display element;
The display device according to claim 1. The display device according to claim 6, wherein the first display area potential line is the black potential line, and the second display area potential line is the white potential line.

Images